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Sample records for xrd hrtem magnetic

  1. IEEE TRANSACTIONS ON MAGNETICS, VOL. 45, NO. 10, OCTOBER 2009 4861 NSOM/HRTEM Characterization of Biologically Derived

    E-print Network

    Mittal, Aditya

    IEEE TRANSACTIONS ON MAGNETICS, VOL. 45, NO. 10, OCTOBER 2009 4861 NSOM/HRTEM Characterization­octahedral facets. Microdiffraction analysis suggests that the magnetic nanoparticles have a composition close to Fe insights into the magnetic properties of the nanomagnets inside bacterial cells with imaging done on single

  2. HRTEM, SAED and XRD investigations of RE{sub 4}O{sub 4}[AsO{sub 4}]Cl (RE = La, Pr, Nd, Sm, Eu, Gd)

    SciTech Connect

    Ben Yahia, Hamdi; Rodewald, Ute Ch.; Boulahya, Khalid; Pöttgen, Rainer

    2014-05-01

    Graphical abstract: The new compounds RE{sub 4}O{sub 4}[AsO{sub 4}]Cl (RE = La, Pr, Nd, Sm, Eu, Gd) were synthesised by solid state reaction via a salt flux route and investigated by HRTEM, SAED, and single crystal X-ray diffraction. - Highlights: • We discovered the series of RE{sub 4}O{sub 4}[AsO{sub 4}]Cl (RE = La, Pr, Nd, Sm, Eu, Gd) compounds. • The RE{sub 4}O{sub 4}[AsO{sub 4}]Cl single crystals were grown using NaCl/KCl flux. • The RE{sub 4}O{sub 4}[AsO{sub 4}]Cl structures were solved using single crystal X-ray diffraction data. • The layered RE{sub 4}O{sub 4}[AsO{sub 4}]Cl compounds were further characterized using HRTEM and SAED. • We observed an alternation of ordered-[RE{sub 4}O{sub 4}]{sup 4+} and disordered-[ClAsO{sub 4}]{sup 4–} layers. - Abstract: The new compounds RE{sub 4}O{sub 4}[AsO{sub 4}]Cl (RE = La, Pr, Nd, Sm, Eu, Gd) were synthesised by solid state reaction via a salt flux route and investigated by HRTEM, SAED, and single crystal X-ray diffraction. The samples crystallise with a tetragonal cell, space group P4{sub 2}/mnm and Z = 2. Their crystal structure consists of an alternation of [RE{sub 4}O{sub 4}]{sup 4+} and [ClAsO{sub 4}]{sup 4–} layers. The [RE{sub 4}O{sub 4}]{sup 4+} layer contains ORE{sub 4/4} tetrahedra which share common edges. The anions AsO{sub 4}{sup 3–} and Cl{sup –} are located between these layers in disordered manner. SAED and HRTEM experiments confirmed this structural model and enabled us to propose an ordered model for the [ClAsO{sub 4}]{sup 4–} layers.

  3. High Resolution Transmission Electron Microscopy (HRTEM) of nanophase ferric oxides

    NASA Technical Reports Server (NTRS)

    Golden, D. C.; Morris, R. V.; Ming, D. W.; Lauer, H. V., Jr.

    1994-01-01

    Iron oxide minerals are the prime candidates for Fe(III) signatures in remotely sensed Martian surface spectra. Magnetic, Mossbauer, and reflectance spectroscopy have been carried out in the laboratory in order to understand the mineralogical nature of Martian analog ferric oxide minerals of submicron or nanometer size range. Out of the iron oxide minerals studied, nanometer sized ferric oxides are promising candidates for possible Martian spectral analogs. 'Nanophase ferric oxide (np-Ox)' is a generic term for ferric oxide/oxihydroxide particles having nanoscale (less than 10 nm) particle dimensions. Ferrihydrite, superparamagnetic particles of hematite, maghemite and goethite, and nanometer sized particles of inherently paramagnetic lepidocrocite are all examples of nanophase ferric oxides. np-Ox particles in general do not give X-ray diffraction (XRD) patterns with well defined peaks and would often be classified as X-ray amorphous. Therefore, different np-Oxs preparations should be characterized using a more sensitive technique e.g., high resolution transmission electron microscopy (HRTEM). The purpose of this study is to report the particle size, morphology and crystalline order, of five np-Ox samples by HRTEM imaging and electron diffraction (ED).

  4. FTIR, magnetic, mass spectral, XRD and thermal studies of metal chelates of tenoxicam

    NASA Astrophysics Data System (ADS)

    Zayed, M. A.; El-Dien, F. A. Nour; Mohamed, Gehad G.; El-Gamel, Nadia E. A.

    2007-09-01

    Metal chelates of anti-inflammatory drug, tenoxicam (Ten), are synthesized and characterized using elemental analyses, IR, solid reflectance, magnetic, mass spectra, thermal analyses (TGA and DTA) and X-ray powder diffraction techniques. The chelates are found to have the general formulae [M(H 2L) 2(H 2O) x] (A) 2· yH 2O (where H 2L = neutral Ten, A = Cl in case of Ni(II) and Co(II) or AcO in case of Cu(II) and Zn(II) ions, x = 0-2 and y = 0-2.5) and [M(H 2L) 3](A) z· yH 2O (A = SO 4 in case of Fe(II) ion ( z = 1) or Cl in case of Fe(III) ( z = 3) and y = 0-4). IR spectra reveal that Ten behaves as a neutral bidentate ligand coordinated to the metal ions through the pyridyl- N and carbonyl- O of the amide moiety. The solid reflectance spectra and magnetic moment measurements reveal that these chelates have tetrahedral, square planar and octahedral geometrical structures. Mass spectra are also used to confirm the proposed formulae and the possible fragments resulted from fragmentation of Ten and its Zn(II) and Cu(II) chelates are suggested. The thermal behaviour of the chelates (TG/DTG, DTA) are discussed in detailed manner and revealed that water molecules of crystallization together with anions are removed in the first and second steps while the Ten molecules are removed in the subsequent steps. Different thermodynamic parameters are evaluated and the relative thermal stabilities of the complexes are discussed. X-ray powder diffraction patterns are used to indicate the polymorphic form of Ten and if the complexes have molecular similarity with respect to type of coordination.

  5. Metallurgy, HRTEM, magnetic properties and specific heat of Tl 2Ba 2Cu 1O 6+? 90 K-superconductors obtained by a new process

    NASA Astrophysics Data System (ADS)

    Opagiste, C.; Couach, M.; Khoder, A. F.; Graf, T.; Junod, A.; Triscone, G.; Muller, J.; Jondo, T. K.; Jorda, J.-L.; Abraham, R.; Cohen-Adad, M. Th.; Bursill, L. A.; Leckel, O.; Blanchin, M. G.

    1993-02-01

    High-quality Tl 2Ba 2CuO 6+? (2201) compounds were synthesized using a high-pressure route. Starting from Tl 2Ba 2O 5 and CuO, the reactions yielding either the orthorhombic or the tetragonal (superconducting) phases were carried out under 100 bar of oxygen or argon and helium, respectively. Preferential thallium losses are prevented and high sintering temperatures can be used to obtain pure samples with large 2201 grains. The experiments performed include metallographic examinations, X-ray diffraction, microprobe analysis, plasma emission spectroscopy, HRTEM, AC susceptibility, Meissner field cooling, hysteresis loops, normal-state susceptibility and specific heat measurements.

  6. EXAFS and SR-XRD study on Mn occupations in Zn 1-xMn xO diluted magnetic semiconductors

    NASA Astrophysics Data System (ADS)

    Li, M.; Zhang, B.; Wang, J. Z.; Shi, L. Q.; Cheng, H. S.; Wang, Y. Z.; Lv, H. Y.; Yang, T. Y.; Wen, W.; Hu, F. C.

    2011-11-01

    Mn-doped ZnO films were prepared by radio frequency (RF) magnetron sputtering on sapphire substrate. Mn content was determined by proton induced X-ray emission (PIXE). Only Mn, no other magnetic impurities such as Fe, Co and Ni were observed. Also, no precipitates such as MnO, Mn 3O 4 and other secondary phases or Mn clusters, were found by SR-XRD, even in Mn-doped content up to 11 at.%. EXAFS analyses showed that Mn atoms were incorporated into ZnO crystal lattice by occupying the sites of zinc atoms.

  7. Magnetic behavior in Ce1-xTbxMn2Si2 silicides by XRD, DSC and AC susceptibility measurements

    NASA Astrophysics Data System (ADS)

    Kervan, S.; Klç, A.; Aksu, E.; Gencer, A.

    2005-12-01

    The structural and magnetic properties the polycrystalline Ce1-xTbxMn2Si2 (0 x 1) compounds were studied by means of X-ray powder diffraction, AC susceptibility and differential scanning calorimetry (DSC). All compounds investigated crystallize in the body-centred tetragonal ThCr2Si2-type structure with the space group I4/mmm. Substitution of Tb for Ce leads to a linear decrease of the lattice constants and the unit cell volume. The lattice constants and the unit cell volume obey Vegard's law. At low temperatures, the rare earth sublattice orders and reconfigures the ordering in the Mn sublattice for x 0.2. The Néel temperature TN(Mn) determined by DSC technique increases linearly with increasing Tb content x. The results are collected in the x-T magnetic phase diagram.

  8. Magnetic properties of NiFe2O4/carbon nanofibers from Venezuelan petcoke

    NASA Astrophysics Data System (ADS)

    Briceño, Sarah; Silva, Pedro; Molina, Wilmer; Brämer-Escamilla, Werner; Alcalá, Olgi; Cañizales, Edgard

    2015-05-01

    NiFe2O4/carbon nanofibers (NiFe2O4/CNFs) have been successfully synthesized by hydrotermal method using Venezuelan petroleum coke (petcoke) as carbon source and NiFe2O4 as catalyst. The morphology, structural and magnetic properties of nanocomposite products were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), vibrating sample magnetometry (VSM) and electron paramagnetic resonance (EPR). XRD analysis revealed a cubic spinel structure and ferrite phase with high crystallinity. HR-TEM reveals the presence of CNFs with diameters of 4±2 nm. At room temperature, NiFe2O4/CNFs show superparamagnetic behavior with a maximum magnetization of 15.35 emu/g. Our findings indicate that Venezuelan petroleum coke is suitable industrial carbon source for the growth of magnetic CNFs.

  9. HRTEM Study of Diesel Soot Collected from Diesel Particulate Filters

    SciTech Connect

    Vander Wal, Randy L.; Yezerets, Aleksey; Currier, Neal; Kim, Do Heui; Wang, Chong M.

    2007-01-01

    HRTEM study of several soot samples collected on Diesel Particulate Filters (DPF) under conditions relevant to practical applications of DPF technology, revealed nano-structure, to our knowledge, not reported previously for diesel soot. In particular, some of the primary particles were found to have hollow interior, and the outer shell exhibiting evidence of graphitization, with a higher crystallinity compared to the non-hollowed particles. The percentage of such particles varied between different soot samples and tentatively appeared to be related to the oxidation history of the sample. Remarkably, similar effect was not reproduced for a carbon black sample, Printex-U, suggesting that propensity to such oxidation-induced graphitization is related to the original nano-structure of the particle. These initial observations were independently confirmed for the same set of soot samples by two different HRTEM facilities, at NASA-Glenn and PNNL.

  10. Carbon nanotube to SiC nanorod conversion in molten salt studied by EELS and aberration corrected HRTEM

    NASA Astrophysics Data System (ADS)

    Xie, W.; Möbus, G.; Zhang, S.

    2010-07-01

    Silicon carbide (SiC) nanorods were prepared via reacting silicon nanopowders and multi-walled carbon nanotubes (MWCNTs) for 4h at 1100-1200°C in a molten NaCl-NaF binary salt in Ar atmosphere. The synthesised SiC nanorods were characterised by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), electron energy loss spectroscopy (EELS), and spherical aberration-corrected FEGTEM. XRD results revealed that MWCNTs had converted into SiC after firing at 1200°C. HRTEM observation showed a complex stacking sequence aligned along the SiC-rod direction. Combination of EELS and aberration-corrected FEGTEM illustrated the resulting nanorod composed of 3C-SiC and some stacking faults. The synthesised SiC nanorods to a large extent retained the morphology of CNT reactants, indicating that the "template-growth" mechanism had dominated the synthesis process. The conversion of MWCNTs into SiC nanorods was strongly dependent on reaction temperature and salt composition. It was found that molten NaCl-NaF binary salts could effectively accelerate the SiC formation.

  11. Synthesis and magnetic characterizations of uniform iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Jiang, FuYi; Li, XiaoYi; Zhu, Yuan; Tang, ZiKang

    2014-06-01

    Uniform iron oxide nanoparticles with a cubic shape were prepared by the decomposition of homemade iron oleate in 1-octadecene with the presence of oleic acid. The particle shape and size uniformity are sensitive to the quantity of oleic acid. XRD, HRTEM and SAED results indicated that the main phase content of as-prepared iron oxide nanoparticles is Fe3O4 with an inverse spinel structure. Magnetic measurements revealed that the as-prepared iron oxide nanoparticles display a ferromagnetic behavior with a blocking temperature of 295 K. At low temperatures the magnetic anisotropy of the aligned nanoparticles caused the appearance of a hysteresis loop.

  12. Synthesis and electro-magnetic properties of flower-like Fe2O3-Ag nanocomposite using direct subsidence loading method

    NASA Astrophysics Data System (ADS)

    Zhou, Xing; Wu, Zhengying; Xu, Nan; Liu, Shouqing; Zhao, Guizhe; Liu, Yaqing

    2015-10-01

    Novel flower-like Fe2O3/Ag nanocomposites were synthesized by a simple direct subsidence loading method. The composition and morphology of the obtained samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SEAD) techniques. The Ag nanoparticles which loaded on the surface of petals exhibit spherical morphology. Further, the magnetic and electrical conductive properties reveal the well controllable performance. Room temperature magnetic measurement of the flower-like nanocomposites demonstrated its ferromagnetic properties and the saturation magnetization (Ms) decreased from 0.6 to 0.11 emu/g.

  13. HRTEM of Quantum Dot Nanostructures: The First 15 Years

    NASA Astrophysics Data System (ADS)

    Rouvimov, S.; Ledentsov, N. N.; Moeck, P.; Shchukin, V. A.; Bimberg, D.

    2008-05-01

    The paper reviews the progress in growth and high resolution transmission electron microscopy (HRTEM) characterization of quantum dot (QD) nanostructures for the last 15 years. Understanding of structural properties of QDs resulted in realization of high-performance quantum dot lasers, amplifiers and single photon devices with precisely engineered properties (polarization, fine structure splitting, defect reduction and defect engineering). Furthermore, advanced QD growth including activated phase separation, submonolayer deposition, and combination of the approaches enabled nanostructures with a high density and uniformity of QDs leading to fabrication of vertical cavity surface emitting QD lasers with 20Gb/s operation in a temperature range 25-85^o C without current or modulation voltage adjustment. The paper addresses current developments and challenges of HREM in application to nanostructures of low dimensionality including electron crystallography (``structural fingerprinting'').

  14. Synthesis and characterization of luminescence magnetic nanocomposite

    NASA Astrophysics Data System (ADS)

    Kiplagat, Ayabei; Onani, Martin O.; Meyer, Mervin; Akenga, Teresa A.; Dejene, Francis B.

    2016-01-01

    We report a new type of indium based quantum dots which were conjugated to the magnetic Fe2O3 nanoparticles. They were characterized by photoluminescence (PL), high resolution transmission electron microscopy (HRTEM), superconducting quantum interference device (SQUID) and fourier transform infra-red (FTIR). The photoluminescence characteristics of the coupled and uncoupled indium based quantum dots were investigated to determine whether the fluorescing property could be retained in the bifunctional system. Generally, the PL intensity of the quantum dots was observed to reduce significantly and with huge red shift most probably due to quenching effects for the MNPs. The average size of the coupled nanoparticles were found to range between 4 and 5 nm for the quantum dots and range of 6-13 nm for the Fe2O3 magnetic nanoparticles as revealed by both HRTEM and XRD. The highest magnetic saturation reached for both bare and functionalized magnetic nanoparticles was 68.58 emu/g. The FTIR data revealed that the postulated functional groups were actually present in both the bare and functionalized nanoparticles. For instance, Fe-O was observed at around 580 cm-1, O-H at 3432 cm-1 and thiol group at 2929 cm-1 for meso-2,3-dimercaptosuccinic acid capped Fe2O3 magnetic nanoparticles. The energy dispersive spectroscopy (EDS) also confirmed that all the elements of the nanocomposite were actually present in the designed material.

  15. Ceramic/metal nanocomposites by lyophilization: Processing and HRTEM study

    SciTech Connect

    Gutierrez-Gonzalez, C.F.; Agouram, S.; Torrecillas, R.; Moya, J.S.; Lopez-Esteban, S.

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer A cryogenic route has been used to obtain ceramic/metal nanostructured powders. Black-Right-Pointing-Pointer The powders present good homogeneity and dispersion of metal. Black-Right-Pointing-Pointer The metal nanoparticle size distributions are centred in 17-35 nm. Black-Right-Pointing-Pointer Both phases, ceramic and metal, present a high degree of crystallinity. Black-Right-Pointing-Pointer Good metal/ceramic interfaces due to epitaxial growth, studied by HRTEM. -- Abstract: This work describes a wet-processing route based on spray-freezing and subsequent lyophilization designed to obtain nanostructured ceramic/metal powders. Starting from the ceramic powder and the corresponding metal salt, a water-based suspension is sprayed on liquid nitrogen. The frozen powders are subsequently freeze-dried, calcined and reduced. The material was analyzed using X-ray diffraction analysis at all stages. High resolution transmission electron microscopy studies showed a uniform distribution of metal nanoparticles on the ceramic grain surfaces, good interfaces and high crystallinity, with an average metal particle size in the nanometric range.

  16. Numerical correction of anti-symmetric aberrations in single HRTEM images

    E-print Network

    Lehtinen, Ossi; Lee, Zhongbo; Whitwick, Michale B; Chen, Ming-Wei; Kis, Andras; Kaiser, Ute

    2014-01-01

    Here, we present a numerical post-processing method for removing the effect of anti-symmetric residual aberrations in high-resolution transmission electron microsopy (HRTEM) images of weak scattering objects. The method is based on applying the same aberrations with the opposite phase to the Fourier transform of the recorded image intensity and subsequently inverting the Fourier transform. We present the theoretical justification of the method and its verification based on simulated images. Ultimately the method is applied to experimental hardware aberration corrected HRTEM images resulting in images with strongly reduced residual aberrations, and consequently improved interpretability. Alternatively, this method can be used to measure accurately residual anti-symmetric aberrations in HRTEM images.

  17. HRTEM study of zircon from Eliseev anorthosite complex, Antarctica

    SciTech Connect

    Wirth, R.; Kaempf, H.; Hoehndorf, A.

    1996-12-31

    Zircon-bearing rocks of this study are metamorphic oxide-apatite gabbronorites (OAGN) from the Eliseev Anorthosite Complex, Wohlthat-Massif, East Antarctica. These unusual rocks are strongly enriched in accessory minerals apatite: <10 vol.%; zircon: < 1 vol.. Three steps in the evolution of these rocks are distinguished: a magnetic formation, followed by a granulite facies metamorphism and finally a tectonomagmatic overprint. The zircon crystals of this study are brown colored, up to 12 mm in length and up to 3 mm wide. Petrological investigations show that zircon has formed during the granulite facies event. Optical microscopy and cathodoluminiscence microscopy reveal a rhythmic zoning and many microcracks. The concentrations of uranium and thorium are low (U: 34-89 ppm and Th: 3-9 ppm). The radiation damage by radioactive decay of U and Th is expected to be minor due to the low uranium and thorium content. The investigations were carried out in a Philips CM200 transmission electron microscope. Analytical electron microscopy was performed by energy dispersive analysis (EDAX).

  18. Aberration Corrected HRTEM of Au Nanoparticles on MgO in a Controlled Gas Atmosphere

    E-print Network

    Dunin-Borkowski, Rafal E.

    Aberration Corrected HRTEM of Au Nanoparticles on MgO in a Controlled Gas Atmosphere Linus D the atomic structures of supported nanoparticles directly under a controlled gas atmosphere [1]. This method nanoparticles supported on MgO in a controlled gas atmosphere, in order to elucidate the mobility of Au surface

  19. A Tool for Local Thickness Determination and Grain Boundary Characterization by CTEM and HRTEM Techniques.

    PubMed

    Kiss, Ákos K; Rauch, Edgar F; Pécz, Béla; Szívós, János; Lábár, János L

    2015-04-01

    A new approach for measurement of local thickness and characterization of grain boundaries is presented. The method is embodied in a software tool that helps to find and set sample orientations useful for high-resolution transmission electron microscopic (HRTEM) examination of grain boundaries in polycrystalline thin films. The novelty is the simultaneous treatment of the two neighboring grains and orienting both grains and the boundary plane simultaneously. The same metric matrix-based formalism is used for all crystal systems. Input into the software tool includes orientation data for the grains in question, which is determined automatically for a large number of grains by the commercial ASTAR program. Grain boundaries suitable for HRTEM examination are automatically identified by our software tool. Individual boundaries are selected manually for detailed HRTEM examination from the automatically identified set. Goniometer settings needed to observe the selected boundary in HRTEM are advised by the software. Operation is demonstrated on examples from cubic and hexagonal crystal systems. PMID:25801740

  20. Fabrication and temperature dependent magnetic properties of Ni-Cu-Co composite nanowires

    NASA Astrophysics Data System (ADS)

    Hussain, Muhammad; Khan, Maaz; Sun, Hongyu; Nairan, Adeela; Karim, Shafqat; Nisar, Amjad; Maqbool, M.; Ahmad, Mashkoor

    2015-10-01

    Ni-Cu-Co composite magnetic nanowires have been successfully synthesized by electrochemical deposition. Microstructural and compositional analyses were carried out using FESEM, TEM, HRTEM and XRD. Magnetic measurements were performed from in the temperature range 5-300 K. A strong diamagnetic contribution, which results from the polycarbonate template, was found to show s-shape behavior of the hysteresis loops of the nanowires. The coercivity of the samples was found to increase with the decreasing temperature following simple model of thermal activation of particle's moment over the anisotropy barrier in the temperature range 50-300 K. Saturation magnetization was found to increase with decreasing temperature following the modified Bloch's law at low temperatures.

  1. Synthesis, characterization and magnetic properties of hematite (?-Fe2O3) nanoparticles on polysaccharide templates and their antibacterial activity

    NASA Astrophysics Data System (ADS)

    Rafi, M. Mohamed; Ahmed, K. Syed Zameer; Nazeer, K. Prem; Siva Kumar, D.; Thamilselvan, M.

    2015-04-01

    The present study is to synthesize iron oxide nanoparticles on different polysaccharide templates calcined at controlled temperature, characterizing them for spectroscopic and magnetic studies leading to evaluate their antibacterial property. The synthesized iron oxide nanoparticles were characterized by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy, high resolution scanning electron microscopy (HRSEM), high resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer. The iron oxide nanoparticles were tested for antibacterial activity against gram-positive and gram-negative bacterial species. The XRD confirms the crystalline nature of iron oxide nanoparticles with the mean crystallite size of 10 nm. The functional groups of the synthesized iron oxide nanoparticles were 547, 543 and 544 cm-1 characterizing the Fe-O and the broad bands at 3,398, 3,439 and 3,427 cm-1 were attributed to the stretching vibrations of hydroxyl group absorbed by iron oxide nanoparticles. HRTEM analyses revealed that the average particle size of the hematite nanoparticles are about 85, 92 and 77 nm for AF, DF and GF, respectively, which was a coincident with the results obtained from the HRSEM analysis. Magnetic measurement exhibited ferromagnetic behavior of the ?-Fe2O3 at the room temperature with higher coercivity of H C = 2,303, 2,333 and 1,019 Oe for AF, DF and GF, respectively. Antibacterial test showed the inhibition against Aeromonas hydrophila and Escherichia coli with significant antagonistic activity.

  2. Study on immobilization of yeast alcohol dehydrogenase on nanocrystalline Ni-Co ferrites as magnetic support.

    PubMed

    Shakir, Mohammad; Nasir, Zeba; Khan, Mohd Shoeb; Lutfullah; Alam, Md Fazle; Younus, Hina; Al-Resayes, Saud Ibrahim

    2015-01-01

    The covalent binding of yeast alcohol dehydrogenase (YADH) enzyme complex in a series of magnetic crystalline Ni-Co nanoferrites, synthesized via sol-gel auto combustion technique was investigated. The structural analysis, morphology and magnetic properties of Ni-Co nanoferrites were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), vibrating-sample magnetometer (VSM), high resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectroscopy (FTIR). The comparative analysis of the HRTEM micrographs of bare magnetic nanoferrite particles and particles immobilized with enzyme revealed an uniform distribution of the particles in both the cases without undergoing change in the size which was found to be in the range 20-30 nm. The binding of YADH to Ni-Co nanoferrites and the possible binding mechanism have been suggested by comparing the FTIR results. The binding properties of the immobilized YADH enzyme were also studied by kinetic parameters, optimum operational pH, temperature, thermal stability and reusability. The immobilized YADH exhibits enhanced thermal stability as compared to the free enzyme over a wide range of temperature and pH, and showed good durability after recovery by magnetic separation for repeated use. PMID:25450541

  3. Transport and magnetic properties of cobalt disulfide prepared by solid state hybrid microwave heating and hot pressing

    NASA Astrophysics Data System (ADS)

    Ouyang, Ting; Xie, Mianyu; Shi, Yunfeng; Chen, Bing; Lan, Yu; Yue, Song

    2015-07-01

    In this study, single phase cobalt disulfide (CoS2) was synthesized by temperature-controlled solid state hybrid microwave heating. The structure, composition and morphology of the obtained samples were studied using X-ray diffraction (XRD), scanning electron spectroscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and high resolution transmission electron microscopy (HRTEM), respectively. The loose CoS2 polycrystalline precursor was then hot pressed to dense bulk sample. The subsequent transport and magnetic properties measurements reveal the ferromagnetic Curie temperature at the magnetic transition near 128 K. These results suggest that the magnetic transition in CoS2 is susceptible to the preparation conditions and the microstructure of the samples.

  4. HRTEM and X-ray diffraction analysis of Au wire bonding interface in microelectronics packaging

    NASA Astrophysics Data System (ADS)

    Junhui, Li; Ruishan, Wang; Lei, Han; Fuliang, Wang; Zhili, Long

    2011-01-01

    Interfacial microstructures of thermosonic Au wire bonding to an Al pad of die were investigated firstly by high-resolution transmission electron microscopy (HRTEM) and X-ray micro-diffractometer. The equal-thickness interference structures were observed by HRTEM due to diffusion and reaction activated by ultrasonic and thermal at the Au/Al bond interface. And X-ray diffraction results showed that three different interplanar crystal spacings ('d' value) of the interfacial microstructures were 2.2257 Å, 2.2645 Å, and 2.1806 Å respectively from the high intensity of diffraction to the low intensity of diffraction. These indicated that the intermetallic phase AlAu 2 formed within a very short time. It would be helpful to further research wire bonding technology.

  5. HRTEM Study of the Role of Nanoparticles in ODS Ferritic Steel

    SciTech Connect

    Hsiung, L; Tumey, S; Fluss, M; Serruys, Y; Willaime, F

    2011-08-30

    Structures of nanoparticles and their role in dual-ion irradiated Fe-16Cr-4.5Al-0.3Ti-2W-0.37Y{sub 2}O{sub 3} (K3) ODS ferritic steel produced by mechanical alloying (MA) were studied using high-resolution transmission electron microscopy (HRTEM) techniques. The observation of Y{sub 4}Al{sub 2}O{sub 9} complex-oxide nanoparticles in the ODS steel imply that decomposition of Y{sub 2}O{sub 3} in association with internal oxidation of Al occurred during mechanical alloying. HRTEM observations of crystalline and partially crystalline nanoparticles larger than {approx}2 nm and amorphous cluster-domains smaller than {approx}2 nm provide an insight into the formation mechanism of nanoparticles/clusters in MA/ODS steels, which we believe involves solid-state amorphization and re-crystallization. The role of nanoparticles/clusters in suppressing radiation-induced swelling is revealed through TEM examinations of cavity distributions in (Fe + He) dual-ion irradiated K3-ODS steel. HRTEM observations of helium-filled cavities (helium bubbles) preferably trapped at nanoparticle/clusters in dual-ion irradiated K3-ODS are presented.

  6. HRTEM image simulations for the study of ultra-thin gate oxides

    SciTech Connect

    Taylor, Seth T.; Mardinly, John; O'Keefe, Michael A.

    2001-07-17

    We have performed high resolution transmission electron microscope (HRTEM) image simulations to qualitatively assess the visibility of various structural defects in ultra-thin gate oxides of MOSFET devices, and to quantitatively examine the accuracy of HRTEM in performing gate oxide metrology. Structural models contained crystalline defects embedded in an amorphous 16 {angstrom}-thick gate oxide. Simulated images were calculated for structures viewed in cross-section. Defect visibility was assessed as a function of specimen thickness and defect morphology, composition, size and orientation. Defect morphologies included asperities lying on the substrate surface, as well as ''bridging'' defects connecting the substrate to the gate electrode. Measurements of gate oxide thickness extracted from simulated images were compared to actual dimensions in the model structure to assess TEM accuracy for metrology. The effects of specimen tilt, specimen thickness, objective lens defocus and coefficient of spherical aberration (C{sub s}) on measurement accuracy were explored for nominal 10{angstrom} gate oxide thickness. Results from this work suggest that accurate metrology of ultra-thin gate oxides (i.e. limited to several per cent error) is feasible on a consistent basis only by using a C{sub s}-corrected microscope. However, fundamental limitations remain for characterizing defects in gate oxides using HRTEM, even with the new generation of C{sub s}-corrected microscopes.

  7. In-situ synthesis of magnetic (NiFe{sub 2}O{sub 4}/CuO/FeO) nanocomposites

    SciTech Connect

    Srivastava, Manish; Ojha, Animesh K.; Chaubey, S.; Singh, Jay

    2010-11-15

    In-situ synthesis of magnetic nanocomposites with (NiFe{sub 2}O{sub 4}/CuO/FeO) crystal phases has been done using a sol-gel method by taking a non-stoichiometric composition of the precursors. The average particle size of the nanocomposites was calculated using X-ray diffraction (XRD) and high resolution tunneling electron microscope (HR-TEM) and it turns out to be {approx}20 nm. The vibrating sample magnetometer (VSM) measurements demonstrate the ferromagnetic nature of the nanocomposites. The synthesized nanocomposite was used to prepare magnetic fluid using tetramethylammonium hydroxide as a surfactant and its stability in the solution was also discussed. -- Graphical abstract: Magnetic nanocomposites containing (NiFe{sub 2}O{sub 4}/CuO/FeO) phases having particle size {approx}17 nm were synthesized by a sol-gel method. The synthesized nanocomposites exhibit ferromagnetic nature with small value of coercivity.

  8. HRTEM of microcrystalline opal in chert and porcelanite from the Monterey Formation, California

    SciTech Connect

    Cady, S.L.; Wenk, H.R.; Downing, K.H.

    1996-11-01

    Microcrystalline opal was investigated using low-dose transmission electron microscopy (TEM) methods to identify microstructural characteristics and possible phase-transformation mechanisms that accommodate silica diagenesis. High-resolution TEM (HRTEM) revealed that microcrystalline opal in opal-CT chert (>90 wt% silica) and opal-CT porcelanite (50-90 wt% silica) from the Miocene Monterey Formation of California displays various amounts of structural disorder and coherent and incoherent lamellar intergrowths. Species of microfibrous opal identified by HRTEM in early-formed opal-CT chert include length-slow opal-C and unidimensionally disordered length-slow opal-CT ({open_quotes}lussatite{close_quotes}). These fibers often display a microstructure characterized by an aperiodic distribution of highly strained domains that separate ordered domains located at discrete positions along the direction of the fiber axes. Microfibrous opal occurs as several types of fiber-aggregation forms. TEM revealed that the siliceous matrix in later-formed opal-CT porcelanite consists of equidimensional, nanometer-size opal-CT crystallites and lussatite fibers. Pseudo-orthorhombic tridymite (PO-2) was identified by HRTEM in one sample of opal-CT porcelanite. Burial diagenesis of chert and porcelanite results in the precipitation of opal-C and the epitaxial growth of opal-C domains on opal-CT substrates. Diagenetic maturation of lussatite was identified by TEM in banded opal-CT-quartz chert to occur as a result of solid-state ordering. The primary diagenetic silica phase transformations between noncrystalline opal, microcrystalline opal, and quartz occur predominantly by a series of dissolution-precipitation reactions. However, TEM showed that in banded opal-CT-quartz chert, the epitaxial growth of quartz on microfibrous opal enhances the rate of silica diagenesis.

  9. Aloe vera plant-extracted solution hydrothermal synthesis and magnetic properties of magnetite (Fe3O4) nanoparticles

    NASA Astrophysics Data System (ADS)

    Phumying, Santi; Labuayai, Sarawuth; Thomas, Chunpen; Amornkitbamrung, Vittaya; Swatsitang, Ekaphan; Maensiri, Santi

    2013-06-01

    Magnetite (Fe3O4) nanoparticles have been successfully synthesized by a novel hydrothermal method using ferric acetylacetonate (Fe(C5H8O2)3) and aloe vera plant-extracted solution. The influences of different reaction temperatures and times on the structure and magnetic properties of the synthesized Fe3O4 nanoparticles were investigated. The synthesized nanoparticles are crystalline and have particle sizes of ˜6-30 nm, as revealed by transmission electron microscopy (TEM). The results of X-ray diffraction (XRD), High resolution TEM (HRTEM) and selected area electron diffraction (SAED) indicate that the synthesized Fe3O4 nanoparticles have the inverse cubic spinel structure without the presence of any other phase impurities. The hysteresis loops of the Fe3O4 nanoparticles at room temperature show superparamagnetic behavior and the saturation magnetization of the Fe3O4 samples increases with increasing reaction temperature and time.

  10. A HRTEM study on serpentinized peridotite from the Southwest Indian Ridge and implications for the deep ocean hydrothermal system

    NASA Astrophysics Data System (ADS)

    Chen, T.; Jin, Z.; Li, W.; Li, H.

    2013-12-01

    Abyssal peridotites generate at mid-ocean ridges. Along the Earth's mid-ocean ridges, abyssal peridotites undergo hydration reactions to become serpentinite minerals, especially in slow to ultraslow spreading mid-ocean ridges. The Southwest Indian Ridge (SWIR) is one of the two ultraslow spreading ridges in the world. The studied serpentinized peridotite sample was collected by the 21st Voyage of the Chinese oceanic research ship Dayang Yihao (aka Ocean No. 1) from a hydrothermal field (63.5°E, 28.0°S, and 3660 m deep) in SWIR. Serpentinized reaction has attracted increasing attention as they are an expression of mantle hydration and water cycles in the deep Earth. There are three main types of serpentinite, antigorite (forms at T > 300°c ), lizadite (forms at T < 200°c ), and chrysotile (forms at intermediate temperatures) [1]. The mineral assemblages of the SWIR serpentinized peridotite was determined by petrography and XRD techniques, which comprises lizardite, chrysotile, olivine, orthopyroxene, clinopyroxene, spinel, magnetite, and chlorite. From SEM and TEM study, serpentinized olivine and orthopyroxene were found changed to chrysotile. However, seldom lizadite was found coexisting with chrysotile in clinopyroxene. From nanobeam SAED and HRTEM analysis, it was observed that the topological structure between lizadite and clinopyroxene is [100]cpx//[001]liz, while there is no topological relationship between chrysotile and clinopyroxene. A little chlorite was observed in serpentine vein, and some nanometer-sized amphibole was observed existing at the side of serpentine vein with [100]cpx//[001]amp. Chrysotile is the dominant serpentine mineral composition in this sample, which is different from most seafloor serpentinized peridotite [2]. The coexistence of chrysotile and lizadite indicates hydration temperature below 300°c , while the existence of chlorite and amphibole suggest hydration temperature reaching greenschist facies conditions, i.e. above 300°c, in the east part of SWIR [1, 2]. Acknowledgments: This work was supported by NSFC (41172050) and CSC. The electron microscopy was accomplished at the Electron Microscopy Center at Argonne National Laboratory, a U.S. Department of Energy Office of Science Laboratory operated under Contract No. DE-AC02-06CH11357 by UChicago Argonne, LLC. References [1] O'Hanley, D.S. Serpentinites. 1984. [2] Mével, C., Geoscience, 335:825, 2003.

  11. Numerical correction of anti-symmetric aberrations in single HRTEM images of weakly scattering 2D-objects.

    PubMed

    Lehtinen, Ossi; Geiger, Dorin; Lee, Zhongbo; Whitwick, Michael Brian; Chen, Ming-Wei; Kis, Andras; Kaiser, Ute

    2015-04-01

    Here, we present a numerical post-processing method for removing the effect of anti-symmetric residual aberrations in high-resolution transmission electron microscopy (HRTEM) images of weakly scattering 2D-objects. The method is based on applying the same aberrations with the opposite phase to the Fourier transform of the recorded image intensity and subsequently inverting the Fourier transform. We present the theoretical justification of the method, and its verification based on simulated images in the case of low-order anti-symmetric aberrations. Ultimately the method is applied to experimental hardware aberration-corrected HRTEM images of single-layer graphene and MoSe? resulting in images with strongly reduced residual low-order aberrations, and consequently improved interpretability. Alternatively, this method can be used to estimate by trial and error the residual anti-symmetric aberrations in HRTEM images of weakly scattering objects. PMID:25458188

  12. Room temperature optical and magnetic properties of polyvinylpyrrolidone capped ZnO nanoparticles

    SciTech Connect

    Chakrabarti, Mahuya; Chakrabarti, Keka R.; Sanyal, D.; Chakrabarti, A.

    2009-09-15

    Defect induced room temperature ferromagnetic properties of polyvinylpyrrolidone (PVP) capped nanocrystalline ZnO samples have been studied. Crystal phase and the lattice parameter of the synthesized nanocrystalline samples have been determined from X-ray diffraction spectra (XRD) and high-resolution transmission electron micrographs (HR-TEM). Room temperature photoluminescence (PL) spectrum for the bare ZnO sample shows a strong band at {approx} 379 nm and another band at {approx} 525 nm. The PL spectra also revealed that the number of oxygen vacancies in the uncapped sample is more than the PVP capped sample. Both sample exhibit ferromagnetic property at room temperature when annealed at 500 deg. C for 3 h, due to the formation of adequate oxygen vacancy related defects. The saturation magnetization for the annealed PVP capped sample is found to be larger compared to that for the uncapped sample.

  13. Synthesis of magnetic GdC2 nanoparticles using cavitation plasma

    NASA Astrophysics Data System (ADS)

    Chaudhary, Rakesh; Koymen, Ali R.

    2015-03-01

    Gadolinium dicarbide (GdC2) nanoparticles were synthesized using Gd electrodes in toluene. Gd nanoparticles are formed in plasma caused due to collapse of cavitation bubbles using ultrasonication in electric field between Gd wire electrodes. The presence of a single phase of GdC2 nanocrystals have been determined by X-Ray Diffraction (XRD) and High Resolution Transmission Electron Microscopy (HRTEM). The GdC2 nanoparticles have tetragonal crystal structure. Transmission Electron Microscopy (TEM) shows that the nanoparticles range in size of 4-45 nm in diameter. Magnetization measurements performed using a Superconducting Quantum Interference Device (SQUID) magnetometer shows GdC2nanoparticles are paramagnetic in nature. To the best of our knowledge, this is the first synthesis of GdC2 in single phase form, allowing further characterization of physical properties.

  14. TEM and HRTEM of Soot-in-oil particles and agglomerates from internal combustion engines

    NASA Astrophysics Data System (ADS)

    Fay, M. W.; La Rocca, A.; Shayler, P. J.

    2014-06-01

    Over time, the performance of lubricating oil in a diesel engine is affected by the build-up of carbon soot produced by the combustion process. TEM and HRTEM are commonly used to investigate the characteristics of individual and agglomerated particles from diesel exhaust, to understand the structure and distribution of the carbon sheets in the primary particles and the nanostructure morphology. However, high resolution imaging of soot-in-oil is more challenging, as mineral oil is a contaminant for the electron microscope and leads to instability under the electron beam. In this work we compare solvent extraction and centrifugation techniques for removing the mineral oil contaminant, and the effect on particle size distribution.

  15. The chaotic points and XRD analysis of Hg-based superconductors

    NASA Astrophysics Data System (ADS)

    Aslan, Ö.; Güven Özdemir, Z.; Keskin, S. S.; Onba?li, Ü.

    2009-03-01

    In this article, high Tc mercury based cuprate superconductors with different oxygen doping rates have been examined by means of magnetic susceptibility (magnetization) versus temperature data and X-ray diffraction pattern analysis. The under, optimally and over oxygen doping procedures have been defined from the magnetic susceptibility versus temperature data of the superconducting sample by extracting the Meissner critical transition temperature, Tc and the paramagnetic Meissner temperature, TPME, so called as the critical quantum chaos points. Moreover, the optimally oxygen doped samples have been investigated under both a.c. and d.c. magnetic fields. The related a.c. data for virgin(uncut) and cut samples with optimal doping have been obtained under a.c. magnetic field of 1 Gauss. For the cut sample with the rectangular shape, the chaotic points have been found to occur at 122 and 140 K, respectively. The Meissner critical temperature of 140 K is the new world record for the high temperature oxide superconductors under normal atmospheric pressure. Moreover, the crystallographic lattice parameters of superconducting samples have a crucial importance in calculating Josephson penetration depth determined by the XRD patterns. From the XRD data obtained for under and optimally doped samples, the crystal symmetries have been found in tetragonal structure.

  16. Synthesis, structure, and magnetic studies on the CoFe2O4-BiFeO3 nanocomposite films with different number of CoFe2O4 layers

    NASA Astrophysics Data System (ADS)

    Liu, Y. Q.; Zhang, B.; Wu, Y. H.; Zhang, J.; Li, D.; Liu, Y.; Wei, M. B.; Yang, J. H.

    2013-09-01

    The multiferroic heterostructures consisting of CoFe2O4 (CFO)-BiFeO3 (BFO) layers with increasing the number of CFO layers (2, 4, 6 and 8) have been grown on LaNiO3 buffered Si (1 0 0) substrate by a simple sol-gel spin-coating route. X-ray diffraction (XRD) shows that the CFO and BFO phases have been successfully retained in the heterostructures and the films are polycrystalline. The high resolution transmission electron microscope (HRTEM) images show the clear interplanar distances and the interface between the two phases. The magnetization (M) versus field (H) loops reveal that, with increasing the CFO layers, the magnetization of CFO-BFO films will be enhanced. The Ms, Mr and Hc of the composite film with 8 CFO layers are measured to be the largest values of 1304 emu/cm3, 562 emu/cm3 and 2074 Oe, respectively.

  17. Nanostructure investigation of magnetic nanomaterial Ni0.5Zn0.3Cu0.2Fe2O4 synthesized by sol-gel method

    NASA Astrophysics Data System (ADS)

    Pransisco, Prengki; Shafie, Afza; Guan, Beh Hoe

    2015-07-01

    Magnetic nanomaterial Ni0.5Zn0.3Cu0.2Fe2O4 was successfully prepared by using sol-gel method. Heat treatment on material is always giving defect on properties of material. This paper investigates the effect of heat treatment on nanostructure of magnetic nanomaterial Ni0.5Zn0.3Cu0.2Fe2O4. According to thermo gravimetric analysis (TGA) that after 600°C there is no more weight loss detected and it was decided as minimum calcination temperature. Intensity, crystallite size, structure, lattice parameter and d-spacing of the material were investigated by using X-ray diffraction (XRD). High resolution transmission electron microscope (HRTEM) was used to examine nanostructure, nanosize, shape and distribution particle of magnetic material Ni0.5Zn0.3Cu0.2Fe2O4 and variable pressure field emission scanning electron microscope (VP-FESEM) was used to investigate the surface morphology and topography of the material. The XRD result shows single-phase cubic spinel structure with average crystallite size in the range of 25.6-95.9 nm, the value of the intensity of the material was increased with increasing temperature, and followed by lattice parameter was increased with increasing calcination temperature, value of d-spacing was relatively decreased with accompanied increasing temperature. From HRTEM result the distribution of particles was tend to be agglomerates with particle size of 7.8-17.68 nm. VP-FESEM result shows that grain size of the material increases with increasing calcination temperature and the surface morphology shows that the material is in hexagonal shape and it was also proved by mapping result which showing the presence each of constituents inside the compound.

  18. HRTEM Study of Oxide Nanoparticles in K3-ODS Ferritic Steel Developed for Radiation Tolerance

    SciTech Connect

    Hsiung, L; Fluss, M; Tumey, S; Kuntz, J; El-Dasher, B; Wall, M; Choi, W; Kimura, A; Willaime, F; Serruys, Y

    2009-11-02

    Crystal and interfacial structures of oxide nanoparticles and radiation damage in 16Cr-4.5Al-0.3Ti-2W-0.37 Y{sub 2}O{sub 3} ODS ferritic steel have been examined using high-resolution transmission electron microscopy (HRTEM) techniques. Oxide nanoparticles with a complex-oxide core and an amorphous shell were frequently observed. The crystal structure of complex-oxide core is identified to be mainly monoclinic Y{sub 4}Al{sub 2}O{sub 9} (YAM) oxide compound. Orientation relationships between the oxide and the matrix are found to be dependent on the particle size. Large particles (> 20 nm) tend to be incoherent and have a spherical shape, whereas small particles (< 10 nm) tend to be coherent or semi-coherent and have a faceted interface. The observations of partially amorphous nanoparticles and multiple crystalline domains formed within a nanoparticle lead us to propose a three-stage mechanism to rationalize the formation of oxide nanoparticles containing core/shell structures in as-fabricated ODS steels. Effects of nanoparticle size and density on cavity formation induced by (Fe{sup 8+} + He{sup +}) dual-beam irradiation are briefly addressed.

  19. PIXE, SR-XRD and EXAFS analysis of Cu-doped ZnO films

    NASA Astrophysics Data System (ADS)

    Zhang, B.; Yang, C.; Wang, J. Z.; Shi, L. Q.; Cheng, H. S.

    2014-08-01

    Cu-doped ZnO films were prepared by rf magnetron sputtering on sapphire substrate at different atmosphere. Microstructure of these films and Cu occupation sites were investigated using PIXE, SR-XRD and EXAFS. Only 2.9 at.% Cu, no other magnetic impurities (e.g., Fe, Co and Ni) were detected. The ZnO:Cu films possessed the wurtzite ZnO structures and no precipitates (e.g., CuO and Cu2O or Cu cluster) were found. Cu atoms were incorporated into ZnO crystal lattice by occupying Zn atomic sites.

  20. HRTEM study of track evolution in 120-MeV U irradiated Gd2Ti2O7

    SciTech Connect

    Jozwik Biala, Iwona; Jagielski, Jacek K.; Thome, Lionel; Arey, Bruce W.; Kovarik, Libor; Sattonay, G.; Debelle, A.; Monnet, I.

    2012-09-01

    High resolution Scanning Transmission Electron Microscopy (HRTEM) experiments were performed on Gd2Ti2O7 pyrochlores irradiated with 120-MeV U ions. A judicious choice of irradiation energy, sample preparation (using Focused Ion Beam) and analytical technique (HRTEM) allowed us to visualize the complete evolution of tracks from the surface of samples down to depths exceeding the projected range of irradiating ions. Such features as variation of track diameters, changes in track directions and discontinuous segments of tracks were clearly documented at various depths. By using two different STEM imaging modes: High- and Low-Angle Annular Dark Field imaging (HAADF and LAADF), it was possible to observe the layered structure of tracks composed of an amorphous core surrounded by a strained crystalline envelope.

  1. Seed-mediated synthesis, properties and application of {gamma}-Fe{sub 2}O{sub 3}-CdSe magnetic quantum dots

    SciTech Connect

    Lin, Alex W.H.; Ang, Chung Yen; Patra, Pranab K.; Han Yu; Gu Hongwei; Le Breton, Jean-Marie; Juraszek, Jean; Chiron, Hubert; Papaefthymiou, Georgia C.; Tamil Selvan, Subramanian; Ying, Jackie Y.

    2011-08-15

    Seed-mediated growth of fluorescent CdSe quantum dots (QDs) around {gamma}-Fe{sub 2}O{sub 3} magnetic cores was performed at high temperature (300 deg. C) in the presence of organic surfactants. Bi-functional magnetic quantum dots (MQDs) with tunable emission properties were successfully prepared. The as-synthesized MQDs were characterized by high-resolution transmission electron microscopy (HRTEM) and dynamic light scattering (DLS), which confirmed the assembly of heterodimers. When a longer growth period was employed, a homogeneous dispersion of QDs around a magnetic nanoparticle was obtained. The magnetic properties of these nanocomposites were examined. The MQDs were superparamagnetic with a saturation magnetization of 0.40 emu/g and a coercivity of 138 Oe at 5 K. To demonstrate their potential application in bio-labeling, these MQDs were coated with a thin silica shell, and functionalized with a polyethylene glycol (PEG) derivative. The functionalized MQDs were effectively used for the labeling of live cell membranes of 4T1 mouse breast cancer cells and HepG2 human liver cancer cells. - Graphical abstract: (a) HRTEM image of oleic acid capped MPs. The size of MPs ranges from 8 to 10 nm. (b) XRD pattern of {gamma}-Fe{sub 2}O{sub 3} MPs. Highlights: > The fabrication of MQDs through a seed-mediated approach has been demonstrated. > The formation and assembly of these bi-functional nanocomposites have been elucidated. > The MQDs exhibit superparamagnetism and tunable emissions characteristic of the components. > MQDs with thin silica coating were successfully employed in the labeling of cancer cell membranes.

  2. CXMS and XRD analyses of heat treated A533B stainless steel

    NASA Astrophysics Data System (ADS)

    Morelos-López, E.; Cabral-Prieto, A.; Nava, N.; García-Santibañez, F.; Nosetti, C.

    2014-04-01

    Heat induced surface changes on A533B stainless steel were followed by XRD and CXMS techniques. Whereas the XRD patterns of the studied A533B samples were characteristic of ?-Fe phase only, the surface Mössbauer spectrum showed a broad sextet, being fitted with two magnetic patterns whose hyperfine magnetic fields were 33 and 31 T associated with a pure and perturbed ?-Fe phase, respectively and a broad singlet with an isomer shift ? A533 B = -0.115(4) mms-Fe, characteristic of the ?-Fe phase. This singlet, probably, arising from the samples' surface only was further analyzed by using a singlet and a quadrupole doublet. From hyperfine distribution and discrete value calculations of their corresponding hyperfine parameters, the quadrupole interaction was the most affected by thermal treatments ranging from 300° to 700 °C showing a slight decrease at 600 °C. The average values of the hyperfine parameters were ? 1 = - 0.110(6) mms-Fe for the singlet, and ? 2 = -0.081 (6) mms-Fe and ?2 = 0.143(7) mm/s) for the quadrupole doublet, respectively. In spite of the temperature dependence of the quadrupole splitting on the doublet, which was higher than that of the isomer shifts of both patterns, only a single defect type was suggested, being associated with monovacancias near the 57Fe sites.

  3. Zeolite-supported Ni and Mo catalysts for hydrotreatments. 2. HRTEM observations

    SciTech Connect

    Li, D.; Xu, H.; Guthrie, G.D. Jr.

    2000-01-25

    Calcined and sulfided Ni-Mo catalysts supported on ultrastable Y zeolite (USY), NaY zeolite, mordenite, and ZSM-5 were studied by high-resolution electron transmission microscopy (HRTEM) with selected-area electron diffraction (SAED) and energy-dispersive spectroscopy (EDS). Ni and Mo oxide aggregates were rarely observed in the USY-supported Ni-Mo catalyst, indicating that most of Ni and Mo may be incorporated into USY, e.g., supercavities and possibly sodalite cages. However, there were a large number of {alpha}-NiMoO{sub 4} aggregates of different particle sizes in NaY-, mordenite-, and ZSM-5-supported catalysts, and the mordenite-supported catalyst also contained MoO{sub 3} crystals. The {alpha}-NiMoO{sub 4} may be attached to the surface of substrates as individual particles or needle aggregates, it may be disseminated into mordenite particles, or it may even form an isolated sphere (in Ni-Mo/NaY) or a needle (in Ni-Mo/ZSM-5) aggregates. Thus, most of Ni and Mo in NaY-, mordenite-, and ZSM-5-supported catalysts preferentially formed aggregates, although some Mo may have been incorporated into NaY and ZSM-5. After sulfidation, small MoS{sub 2} aggregates containing some Ni were rarely but occasionally found on the surface of USY zeolite; however, there were a large number of such MoS{sub 2} aggregates on the surface of NaY. Separate and intergrown MoS{sub 2} and Ni sulfides aggregates were observed on the surface of mordenite and ZSM-5. The Ni sulfide might be identified by SAED and high-magnification images as troilite-like NiS and/or Ni{sub 9}S{sub 8}, but definitely not as NiS with millerite structure or Ni{sub 3}S{sub 2}. These results indicated that sulfidation does not extensively affect Ni and Mo that have been incorporated into the supercavity and/or sodalite cage of USY in calcined Ni-Mo/USY. The USY-supported Ni-Mo catalyst had a much higher hydrodesulfurization (HDS) activity than the other zeolite-supported catalysts.

  4. Structural and magnetic properties of Gd3+ ion substituted magnesium ferrite nanopowders

    NASA Astrophysics Data System (ADS)

    Elkady, Ashraf S.; Hussein, Shaban I.; Rashad, Mohamed M.

    2015-07-01

    Nanocrystalline MgGdxFe2-xO4 powders (where x=0, 0.05, 0.1, 0.2, 0.25, 0.3) have been synthesized by the ethylene diamine tetraacetic acid (EDTA)-based sol-gel combustion method. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, high resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer (VSM) were applied in order to study the effect of variation of Gd3+ ion substitution and its impact on crystal structure, crystallite size, lattice parameters, nanostructure and magnetic properties of the formed powders. XRD indicated that, after doping and calcination at 400 °C for 2 h, all samples have two spinel ferrite structures namely cubic and tetragonal phases, which are dependent on Gd3+ ion concentration. The cubic phase is found to increase with increasing the Gd3+ ion molar ratio up to 0.1, compared to pure MgFe2O4 and higher Gd3+ content samples. Indeed, with increasing Gd3+ ion, the crystallite size was almost unchanged whereas the lattice parameter was found to increase. FT-IR spectrum showed broadening of the ?2 band and the presence of another band in the range (465-470 cm-1) upon adding Gd3+ ion, which confirm the presence of Gd3+ ion in addition to Fe3+ ion at octahedral site. Besides, these bands were assigned to the formation of (Gd3+-O2-) complexes at B-sites. HRTEM images showed that the studied samples consist of nanocrystallites having average particle sizes around 9 nm for pure MgFe2O4 up to 27 and 42 nm for the Gd3+ ion substituted MgFe2O4 of molar ratio 0.05 and 0.30, respectively. An examination of the magnetic properties revealed an increase in saturation magnetization with increasing Gd concentration incorporation up to x=0.1, as a result of the change of cubic and tetragonal spinel ratio and lattice parameters. Meanwhile, the formed powders exhibited superparamagnetic characteristics. Therefore, such newly synthesized superparamagnetic nanoparticles, containing Gd3+ ion can be considered as a promising candidate for use in several potential applications including neutron capture therapy (NCT), magnetic hyperthermia, ferrofluids and magnetic resonance imaging (MRI).

  5. Qualitative soil mineral analysis by EDXRF, XRD and AAS probes

    NASA Astrophysics Data System (ADS)

    Singh, Virendra; Agrawal, H. M.

    2012-12-01

    Soil minerals study is vital in terms of investigating the major soil forming compounds and to find out the fate of minor and trace elements, essential for the soil-plant interaction purpose. X-ray diffraction (XRD) has been a popular technique to search out the phases for different types of samples. For the soil samples, however, employing XRD is not so straightforward due to many practical problems. In the current approach, principal component analysis (PCA) has been used to have an idea of the minerals present, in qualitative manner, in the soil under study. PCA was used on the elemental concentrations data of 17 elements, determined by the energy dispersive X-ray fluorescence (EDXRF) technique. XRD analysis of soil samples has been done also to identify the minerals of major elements. Some prior treatments, like removal of silica by polytetrafluoroethylene (PTFE) slurry and grinding with alcohol, were given to samples to overcome the peak overlapping problems and to attain fine particle size which is important to minimize micro-absorption corrections, to give reproducible peak intensities and to minimize preferred orientation. A 2? step of 0.05°/min and a longer dwell time than normal were used to reduce interferences from background noise and to increase the counting statistics. Finally, the sequential extraction procedure for metal speciation study has been applied on soil samples. Atomic absorption spectroscopy (AAS) was used to find the concentrations of metal fractions bound to various forms. Applying all the three probes, the minerals in the soils can be studied and identified, successfully.

  6. Synthesis and optical properties of TiO2-based magnetic nanocomposites

    NASA Astrophysics Data System (ADS)

    Scarisoreanu, M.; Morjan, I.; Fleaca, C.-T.; Morjan, I. P.; Niculescu, A.-M.; Dutu, E.; Badoi, A.; Birjega, R.; Luculescu, C.; Vasile, E.; Danciu, V.; Filoti, G.

    2015-05-01

    Magnetic titania nanoparticles covered/embedded in SiO2 shell/matrix were simultaneously manufactured by the single-step laser pyrolysis. The present study is a continuation of our previous investigations on the TiO2/Fe and TiO2/HMDSO (hexamethyldisiloxane) derived-systems. The aim of this work is to study the synthesis by IR (Infrared) laser pyrolysis of magnetic TiO2 based nanocomposites which implies many concurrent processes induced in the gas phase by the laser radiation. The dependence between characteristic properties and the synthesis parameters was determined by many analytical and complementary methods: XRD (X-ray diffraction) structural analysis, UV-vis (ultraviolet-visible) and EDAX (energy-dispersive X-ray) spectroscopy, TEM and HRTEM (transmission electron microscopy at low and high resolution) analysis and magnetic measurements. The results of analysis indicate the presence of disordered silica, Fe, ?-Fe2O3 and mixtures of anatase and rutile phases with mean crystallite dimensions (in the 14-34 nm range) with typical character of diluted magnetic oxide systems and a lower bandgap energy (Eg = 1.85 eV) as compared with TiO2 P25 Degussa sample.

  7. 4-D XRD for strain in many grains using triangulation

    SciTech Connect

    Bale, Hrishikesh A.; Hanan, Jay C.; Tamura, Nobumichi

    2006-12-31

    Determination of the strains in a polycrystalline materialusing 4-D XRD reveals sub-grain and grain-to-grain behavior as a functionof stress. Here 4-D XRD involves an experimental procedure usingpolychromatic micro-beam X-radiation (micro-Laue) to characterizepolycrystalline materials in spatial location as well as with increasingstress. The in-situ tensile loading experiment measured strain in a modelaluminum-sapphire metal matrix composite using the Advanced Light Source,Beam-line 7.3.3. Micro-Laue resolves individual grains in thepolycrystalline matrix. Results obtained from a list of grains sorted bycrystallographic orientation depict the strain states within and amongindividual grains. Locating the grain positions in the planeperpendicular to the incident beam is trivial. However, determining theexact location of grains within a 3-D space is challenging. Determiningthe depth of the grains within the matrix (along the beam direction)involved a triangulation method tracing individual rays that producespots on the CCD back to the point of origin. Triangulation wasexperimentally implemented by simulating a 3-D detector capturingmultiple diffraction images while increasing the camera to sampledistance. Hence by observing the intersection of rays from multiple spotsbelonging to the corresponding grain, depth is calculated. Depthresolution is a function of the number of images collected, grain to beamsize ratio, and the pixel resolution of the CCD. The 4DXRD methodprovides grain morphologies, strain behavior of each grain, andinteractions of the matrix grains with each other and the centrallylocated single crystal fiber.

  8. A Combined XRD/XRF Instrument for Lunar Resource Assessment

    NASA Technical Reports Server (NTRS)

    Vaniman, D. T.; Bish, D. L.; Chipera, S. J.; Blacic, J. D.

    1992-01-01

    Robotic surface missions to the Moon should be capable of measuring mineral as well as chemical abundances in regolith samples. Although much is already known about the lunar regolith, our data are far from comprehensive. Most of the regolith samples returned to Earth for analysis had lost the upper surface, or it was intermixed with deeper regolith. This upper surface is the part of the regolith most recently exposed to the solar wind; as such it will be important to resource assessment. In addition, it may be far easier to mine and process the uppermost few centimeters of regolith over a broad area than to engage in deep excavation of a smaller area. The most direct means of analyzing the regolith surface will be by studies in situ. In addition, the analysis of the impact-origin regolith surfaces, the Fe-rich glasses of mare pyroclastic deposits, are of resource interest, but are inadequately known; none of the extensive surface-exposed pyroclastic deposits of the Moon have been systematically sampled, although we know something about such deposits from the Apollo 17 site. Because of the potential importance of pyroclastic deposits, methods to quantify glass as well as mineral abundances will be important to resource evaluation. Combined x ray diffraction (XRD) and x ray fluorescence (XRF) analysis will address many resource characterization problems on the Moon. XRF methods are valuable for obtaining full major-element abundances with high precision. Such data, collected in parallel with quantitative mineralogy, permit unambiguous determination of both mineral and chemical abundances where concentrations are high enough to be of resource grade. Collection of both XRD and XRF data from a single sample provides simultaneous chemical and mineralogic information. These data can be used to correlate quantitative chemistry and mineralogy as a set of simultaneous linear equations, the solution of which can lead to full characterization of the sample. The use of Rietveld methods for XRD data analysis can provide a powerful tool for quantitative mineralogy and for obtaining crystallographic data on complex minerals.

  9. Structural and magnetic properties of CoFe2O4/NiFe2O4 core/shell nanocomposite prepared by the hydrothermal method

    NASA Astrophysics Data System (ADS)

    Sattar, A. A.; EL-Sayed, H. M.; ALsuqia, Ibrahim

    2015-12-01

    CoFe2O4/NiFe2O4 core/shell magnetic nanocomposite was synthesized by using hydrothermal method.The analysis of XRD indicated the coexistence of CoFe2O4, NiFe2O4as core/shell composite. The core/shell structure of the composite sample has been confirmed by HR-TEM images, EDX and FT-IR measurements. The size of obtained core/shell nanoparticles was 17 nm in core diameter and about 3 nm in shell thickness. The magnetization measurements showed that both the coercive field and the saturation magnetization of the resulting core/shell nanocomposite were slightly decreased compared to those of the CoFe2O4 core but the thermal stability is of the magnetization parameter was enhanced. Furthermore, superparamagnetic phase is established at temperatures higher than the room temperature. The results were discussed in terms of the surface pinning and the magnetic interaction at the interface between the core and shell.

  10. The effect of temperature on the structure and magnetic properties of Co0.5Ni0.5Fe2O4 spinel nanoferrite

    NASA Astrophysics Data System (ADS)

    Abdallah, Hafiz M. I.; Moyo, Thomas; Ngema, Nokwanda

    2015-11-01

    Nanocrystalline Co0.5Ni05Fe2O4 ferrite with average crystallite size of 7.6 nm and lattice constant of 0.8372 nm was synthesized via a glycol-thermal process. The structure parameters and morphology of the as-synthesized sample and annealed samples were characterized by XRD, EDX, FTIR, HRSEM and HRTEM. The hyperfine interactions, iron distribution on the tetrahedral and octahedral sites for the as-synthesized sample and samples annealed at 500 °C were deduced by Mössbauer spectroscopy measurements at 300 K. The magnetization measurements for the as-synthesized and annealed samples (300-900 °C) were obtained by a vibrating sample magnetometer on a cryogen free measurement system at different isothermal temperatures (4-300 K) in external applied magnetic fields of ±5 T. The temperature dependence of the magnetic properties such as coercive field, saturation magnetization, remanent magnetization and squareness of hysteresis loops were investigated. The sample transformed from single-domain to multi-domain configuration at particle size of about 31 nm. At 300 K, the sample annealed at 700 °C exhibits a maximum coercivity. The as-prepared sample shows a substantial increase in coercivity from 0.182 kOe at 300 K to 6.018 kOe at 4 K.

  11. Investigation of the Distribution of Fission Products Silver, Palladium and Cadmium in Neutron Irradiated SIC using a Cs Corrected HRTEM

    SciTech Connect

    I. J. van Rooyen; E. Olivier; J. H Neethlin

    2014-10-01

    Electron microscopy examinations of selected coated particles from the first advanced gas reactor experiment (AGR-1) at Idaho National Laboratory (INL) provided important information on fission product distribution and chemical composition. Furthermore, recent research using STEM analysis led to the discovery of Ag at SiC grain boundaries and triple junctions. As these Ag precipitates were nano-sized, high resolution transmission electron microscopy (HRTEM) examination was used to provide more information at the atomic level. This paper describes some of the first HRTEM results obtained by examining a particle from Compact 4-1-1, which was irradiated to an average burnup of 19.26% fissions per initial metal atom (FIMA), a time average, volume-averaged temperature of 1072°C; a time average, peak temperature of 1182°C and an average fast fluence of 4.13 x 1021 n/cm2. Based on gamma analysis, it is estimated that this particle may have released as much as 10% of its available Ag-110m inventory during irradiation. The HRTEM investigation focused on Ag, Pd, Cd and U due to the interest in Ag transport mechanisms and possible correlation with Pd, Ag and U previously found. Additionally, Compact 4-1-1 contains fuel particles fabricated with a different fuel carrier gas composition and lower deposition temperatures for the SiC layer relative to the Baseline fabrication conditions, which are expected to reduce the concentration of SiC defects resulting from uranium dispersion. Pd, Ag, and Cd were found to co-exist in some of the SiC grain boundaries and triple junctions whilst U was found to be present in the micron-sized precipitates as well as separately in selected areas at grain boundaries. This study confirmed the presence of Pd both at inter- and intragranular positions; in the latter case specifically at stacking faults. Small Pd nodules were observed at a distance of about 6.5 micron from the inner PyC/SiC interface.

  12. Diagenetic Microcrystalline Opal Varieties from the Monterey Formation, CA: HRTEM Study of Structures and Phase Transformation Mechanisms

    NASA Technical Reports Server (NTRS)

    Cady, Sherry L.; Wenk, H.-R.; DeVincenzi, Don (Technical Monitor)

    1994-01-01

    Microcrystalline opal varieties form as intermediary precipitates during the diagenetic transformation of biogenically precipitated non-crystalline opal (opal-A) to microquartz. With regard to the Monterey Formation of California, X-ray powder diffraction studies have shown that a decrease in the primary d-spacing of opal-CT toward that of cristobalite occurs with increasing diagenesis. The initial timing of opal-CT/quartz formation and the value of the primary opal-CT d-spacing, are influenced by the sediment. lithology. Transmission electron microscopy methods (CTEM/HRTEM) were used to investigate the structure of the diagenetic phases and establish transformation mechanisms between the varieties of microcrystalline opals in charts and porcelanites from the Monterey Formation. HRTEM images revealed that the most common fibrous varieties of microcrystalline opals contain varying amounts of structural disorder. Finite lamellar units of cristobalite-and tridymite-type. layer sequences were found to be randomly stacked in a direction perpendicular to the fiber axis. Disordered and ordered fibers were found to have coprecipitated within the same radial fiber bundles that formed within the matrix of the Most siliceous samples. HRTEM images, which reveal that the fibers within radial and lepispheric fiber bundles branch non-crystallographically, support an earlier proposal that microspheres in chert grow via a spherulitic growth mechanism. A less common variety of opal-CT was found to be characterized by non-parallel (low-angle) stacking sequences that often contain twinned lamellae. Tabular-shaped crystals of orthorhombic tridymite (PO-2) were also identified in the porcelanite samples. A shift in the primary d-spacing of opal-CT has been interpreted as an indication of solid-state ordering g toward a predominantly cristobalite structure, (opal-C). Domains of opal-C were identified as topotactically-oriented overgrowths on discrete Sections of opal-CT fibers and as lamellar domains within relict opal-CT fibers. These findings indicate that the type of transformation mechanism depends upon the primary structural characteristics of the authigenic opaline. varieties that are in turn influenced by the sediment lithology.

  13. Effect of calcination temperature on microstructure and magnetic properties of Ni{sub 0.5}Zn{sub 0.25}Cu{sub 0.25} Fe{sub 2}O{sub 4} nanoparticles synthesized by sol-gel method

    SciTech Connect

    Pransisco, Prengki E-mail: afza@petronas.com.my; Shafie, Afza E-mail: afza@petronas.com.my; Guan, Beh Hoe

    2014-10-24

    This paper examines the effect of calcination process on the structural and magnetic properties material nanostructure composite of Ni{sub 0Ð}œ‡{sub 5}Zn{sub 0Ð}œ‡{sub 25}Cu{sub 0.25} Fe{sub 2}O{sub 4} ferrites. The samples were successfully prepared by sol-gel method at different calcination temperature, which are 600°C, 700°C, 800°C and 900°C. Morphological investigation, average crystallite size and microstructure of the material were examined by using X-ray diffraction (XRD) and confirmed by high resolution transmission electron microscope (HRTEM) and field emission scanning electron microscope (FESEM). The effects of calcination temperature on the magnetic properties were calculated by using vibrating sample magnetometer (VSM). The XRD result shows single-phase cubic spinel structure with interval average size 5.9-38 nm, and grain size microstructure of the material was increasing with temperature increases. The highest magnetization saturation was reached at a temperature 800°C with value 53.89 emu/g, and the value coercive force (Hc) was inversely with the grain size.

  14. Structural and magnetic properties of magnesium ferrite nanoparticles prepared via EDTA-based sol-gel reaction

    NASA Astrophysics Data System (ADS)

    Hussein, Shaban I.; Elkady, Ashraf S.; Rashad, M. M.; Mostafa, A. G.; Megahid, R. M.

    2015-04-01

    Magnesium ferrite (MgFe2O4) nanoparticles have been prepared, for the first time, by ethylene diamine tetraacetic acid (EDTA)-based sol-gel combustion method. The prepared ferrite system is calcined at 400, 500 and 600 °C. Thermo-gravimetric and differential thermal analysis (TGA-DTA), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, high resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometry (VSM) were applied for elucidating the structural and magnetic properties of the prepared system. XRD patterns revealed that the prepared system have two spinel MgFe2O4 structures, namely cubic and tetragonal phases that are dependent on calcination temperature (Tc). The crystallite sizes varied from 8.933 to 41.583 nm, and from 1.379 to 292.565 nm for the cubic and tetragonal phases respectively depending on Tc. The deduced lattice parameters for the cubic and (tetragonal) systems are a=8.368, 8.365 and 8.377 and (a=7.011, 5.922, 5.908 and c=6.622, 8.456, 8.364) Å at Tc=400, 500 and 600 °C respectively. While the cation distribution of the cubic phase is found to be mixed spinel and Tc-dependent, it is an inverse spinel in the tetragonal phase where the Fe3+ ions occupy both the tetrahedral A- and octahedral B-sites in almost equal amount; the Mg2+ ions are found to occupy only the B-sites. The HRTEM and selected-area electron diffraction (SAED) revealed the detailed morphology of the nanoparticles, and confirmed their crystalline spinel structure. VSM indicated the existence of an appreciable fraction of superparamagnetic particles at room temperature, with pure superparamagnetic behavior observed for samples calcined at 400 °C. Besides, the magnetic properties are found to change by thermal treatment as a result of the varied phase concentration, cation distribution and lattice parameters. Thus, the new synthesis route used in this study by applying EDTA as an organic precursor for preparing MgFe2O4 nanoparticles at rather low temperatures proved to be efficient in obtaining nanoparticles with favorable structural and magnetic properties. Such properties would qualify them for several potential applications including e.g. in hyperthermia treatment, as contrast agents in magnetic resonance imaging (MRI), and in ferroelastomers technology.

  15. RBS/C, HRTEM and HRXRD study of damage accumulation in irradiated SrTiO3

    SciTech Connect

    Jagielski, Jacek; Jozwik, Przemyslaw A.; Jozwik Biala, Iwona; Kovarik, Libor; Arey, Bruce W.; Gaca, J.; Jiang, Weilin

    2013-05-14

    Damage accumulation in argon-irradiated SrTiO3 single crystals has been studied by using combination of Rutherford Backscattering/Channeling (RBS/C), High Resolution Transmission Electron Microscopy (HRTEM) and High Resolution X-Ray Diffraction (HRXRD) techniques. The RBS/C spectra were fitted using McChasy, a Monte Carlo simulation code allowing the quantitative analysis of amorphous-like and dislocation-like types of defects. The results were interpreted by using a Multi-Step Damage Accumulation model which assumes, that the damage accumulation occurs in a series of structural transformations, the defect transformations are triggered by a stress caused by formation of a free volume in the irradiated crystal. This assumption has been confirmed by High Resolution Transmission Electron Microscopy and High Resolution X-Ray Diffraction analysis.

  16. Synthesis of Iron Oxide Nanoparticles from Iron Acetylacetonate and Cyclopentadienyliron Dicarbonyl Dimer in Low Pressure Plasma — Effect of Plasma Parameters on Morphology and Magnetic Properties

    NASA Astrophysics Data System (ADS)

    Panchal, Vineet; Bhandarkar, Upendra; Neergat, Manoj; Suresh, K. G.

    2015-03-01

    Iron oxide nanoparticles are synthesized using organometallic precursors namely, iron (III) acetylacetonate and cyclopentadienyliron dicarbonyl dimer in a capacitively coupled low pressure plasma system. They are characterized using High Resolution Transmission Electron Microscopy (HRTEM), X-ray Diffraction (XRD), magnetization studies and Raman spectroscopy. The role of hydrogen and RF (Radio Frequency) power on the crystalline and magnetic properties of the nanoparticles is studied. Incorporation of hydrogen to the Plasma-Enhanced Chemical Vapor Deposition (PECVD) chamber during the synthesis facilitates both crystallization of iron oxide nanoparticles and reduction of carbon content in the product. The saturation magnetization of iron oxide nanoparticles synthesized using iron (III) acetylacetonate and cyclopentadienyliron dicarbonyl dimer in presence of hydrogen at 200 W RF power is higher than that synthesized in the absence of hydrogen at 50 W RF power. In case of nanoparticles synthesized using iron (III) acetylacetonate, the saturation magnetization increases from 1.5 emu g-1 to 19 emu g-1, and for the same synthesized from cyclopentadienyliron dicarbonyl dimer it increases from 3.2 emu g-1 to 22.4 emu g-1.

  17. Mechanism of uranium(VI) uptake by Saccharomyces cerevisiae under environmentally relevant conditions: batch, HRTEM, and FTIR studies.

    PubMed

    Lu, Xia; Zhou, Xiao-jiao; Wang, Tie-shan

    2013-11-15

    Biosorption is of significance for the safety evaluation of high-level nuclear wastes repositories and remediation of radioactive contamination places. Quantitive study and structural characterization of uranium uptake by both live and heat-killed Saccharomyces cerevisiae at environmentally relevant uranium concentration and with different ionic strengths were carried out. Kinetic investigation showed the equilibrium reached within 15 min. In equilibrium studies, pH shift towards neutral indicated release of hydroxyl ions. pH was the most important factor, which partly affected electrostatic interaction between uranyl ions and S. cerevisiae surface. The high ionic strength inhibited biosorption capacity, which can be explained by a competitive reaction between sodium ions and uranyl ions. Heat killing process significantly enhanced biosorption capacity, showing an order of magnitude higher than that of live cells. High resolution transmission electron microscopy (HRTEM) coupled with energy dispersive X-ray (EDX) showed needle-like uranium-phosphate precipitation formed on the cell walls for both live and heat-killed cells. Besides, dark-field micrographs displayed considerable similar uranium-phosphate precipitation presented outside the heat-killed cells. The phosphate released during heat-killing process. FTIR illustrated function groups hydroxyl, carboxyl, phosphate, and amino groups played important role in complexation with uranium. PMID:24041822

  18. HRTEM investigations between minerals, fluids and lithobiontic communities during natural weathering. Progress report, September 1, 1993--February 28, 1994

    SciTech Connect

    Banfield, J.F.; Barker, W.W.

    1994-02-01

    HRTEM and AEM analysis of riebeckite and acmite from the interiors of moderately weathered syenite reveals that interaction of these minerals with surficial fluids resulted in the almost complete removal of Na, Ca, and Si. Fe remained relatively immobile, forming arrays of semi-oriented nanocrystalline ferrihydrite and goethite at the primary mineral-secondary mineral interface. The goethite intimately contacts an irregularly corroded amphibole surface. Smectite occurs sporadically as isolated crystallites a few layers thick which are surrounded by goethite. No obvious structural alignment between clay and amphibole or pyroxene was seen. Data suggest that almost all Si is transported in solution to more open regions between islands of nanocrystalline goethite, where it crystallizes as an Fe - rich smectite. Alteration assemblages in wider channels are comprised of euhedral goethite crystals that, within a submicron-sized area, range in size from 5--40 manometers. Sub-grain boundary structures and the porosity distribution suggests evolution of particle size by coarsening. Optical microscopy demonstrates intimate contact between lichen thalli and mineral surfaces. Lichen thalli exploit cracks and open cleavages to extend several millimeters within mineral interiors. Preliminary TEM data suggest the alteration assemblage consists of a polymer-bound mass of chemically complex aluminosilicates.

  19. In-situ HRTEM study of the reactive carbide phase of Co/MoS2 catalyst.

    PubMed

    Ramos, Manuel; Ferrer, Domingo; Martinez-Soto, Eduan; Lopez-Lippmann, Hugo; Torres, Brenda; Berhault, Gilles; Chianelli, Russell R

    2013-04-01

    Hydrotreatment catalytic operations are commonly performed industrially by layered molybdenum sulfide promoted by cobalt or nickel in order to remove heteroelements (S, N, O) from fossil fuels and biofuels. Indeed, these heteroelements are responsible of the emission of pollutants when these fuels are used in vehicles. In this respect, previous studies made by our research group have shown that the active phase under steady state conditions is partially carbided while strong bending effects of MoS2 slabs were also observed. However, up to now, the morphology of the resulting Co/MoSxCy carbided catalyst has not been fully characterized. In the present study, for the first time, a chemical reaction between the carbon content of a TEM Cu/C grid and a freshly sulfide Co/MoS2 catalyst was in situ observed at 300 °C and 450 °C by HRTEM experimental techniques at ~10 nm of resolution. Results indicate that bending of MoS2 layers occurred due to carbon addition on MoS2 edge sites, as observed in stabilized catalysts after HDS reaction. Using a silicon grid, only cracks of MoS2 slabs were observed without bending effect confirming the role of structural-carbon in this change of morphology. PMID:22925737

  20. Remote In-Situ Quantitative Mineralogical Analysis Using XRD/XRF

    NASA Technical Reports Server (NTRS)

    Blake, D. F.; Bish, D.; Vaniman, D.; Chipera, S.; Sarrazin, P.; Collins, S. A.; Elliott, S. T.

    2001-01-01

    X-Ray Diffraction (XRD) is the most direct and accurate method for determining mineralogy. The CHEMIN XRD/XRF instrument has shown promising results on a variety of mineral and rock samples. Additional information is contained in the original extended abstract.

  1. How isopolyanions self-assemble and condense into a 2D tungsten oxide crystal: HRTEM imaging of atomic arrangement in an intermediate new hexagonal phase

    SciTech Connect

    Chemseddine, A. Bloeck, U.

    2008-10-15

    The structure and structural evolution of tungstic acid solutions, sols and gels are investigated by high-resolution electron microscopy (HRTEM). Acidification of sodium tungstate solutions, through a proton exchange resin, is achieved in a way that ensures homogeneity in size and shape of intermediate polytungstic species. Gelation is shown to involve polycondensation followed by a self-assembling process of polytungstic building blocks leading to sheets with a layered hexagonal structure. Single layers of this new metastable phase are composed of three-, four- and six-membered rings of WO{sub 6} octahedra located in the same plane. This is the first time that a 2D oxide crystal is isolated and observed by direct atomic resolution. Further ageing and structural evolution leading to single sheets of 2D ReO{sub 3}-type structure is directly observed by HRTEM. Based on this atomic level imaging, a model for the formation of the oxide network structure involving a self-assembling process of tritungstic based polymeric chain is proposed. The presence of tritungstic groups and their packing in electrochromic WO{sub 3} films made by different techniques is discussed. - Graphical abstract: From the isopolyanion to the extended bulk tungsten oxide: HRTEM imaging.

  2. Mössbauer, TEM/SAED and XRD investigation on waste dumps of the Valea lui Stan gold mines

    NASA Astrophysics Data System (ADS)

    Constantinescu, Serban Grigore; Udubasa, Sorin S.; Udubasa, Gheorghe; Kuncser, Victor; Popescu-Pogrion, Nicoleta; Mercioniu, Ionel; Feder, Marcel

    2012-03-01

    The complementary investigation techniques, Mössbauer spectroscopy, transmission electron microscopy with selected area electron diffraction (TEM/SAED), X-ray diffraction (XRD) have been used to investigate the fate of the Valea lui Stan, Romania, gold-ore nanoscale-minerals during the long time of residence in the waste dumps. The preliminary investigations showed such waste dumps to contain significant amount of metals which cannot be identified by conventional methods. An intense research activity started up in order to evaluate the possibilities to recycle Valea lui Stan waste dumps and to recover metals by chemical or phytoextraction procedures. The waste dumps naturally show different mineral constituents with clay minerals as major phases, observed by XRD-technique. Although the waste dumps materials have whitish-yellowish colours, MÖSSBAUER technique evidences the presence of the finely dispersed iron bearing minerals. The authors are focusing to inspect and analyze Fe-compounds in the samples collected from Valea lui Stan's waste dumps in order to identify the magnetic phases by Mössbauer technique.

  3. Clay pigment structure characterisation as a guide for provenance determination--a comparison between laboratory powder micro-XRD and synchrotron radiation XRD.

    PubMed

    Švarcová, Silvie; Bezdi?ka, Petr; Hradil, David; Hradilová, Janka; Žižak, Ivo

    2011-01-01

    Application of X-ray diffraction (XRD)-based techniques in the analysis of painted artworks is not only beneficial for indisputable identification of crystal constituents in colour layers, but it can also bring insight in material crystal structure, which can be affected by their geological formation, manufacturing procedure or secondary changes. This knowledge might be helpful for art historic evaluation of an artwork as well as for its conservation. By way of example of kaolinite, we show that classification of its crystal structure order based on XRD data is useful for estimation of its provenance. We found kaolinite in the preparation layer of a Gothic wall painting in a Czech church situated near Karlovy Vary, where there are important kaolin deposits. Comparing reference kaolin materials from eight various Czech deposits, we found that these can be differentiated just according to the kaolinite crystallinity. Within this study, we compared laboratory powder X-ray micro-diffraction (micro-XRD) with synchrotron radiation X-ray diffraction analysing the same real sample. We found that both techniques led to the same results. PMID:21104235

  4. Magnetically separable Cu2O/chitosan-Fe3O4 nanocomposites: Preparation, characterization and visible-light photocatalytic performance

    NASA Astrophysics Data System (ADS)

    Cao, Chunhua; Xiao, Ling; Chen, Chunhua; Cao, Qihua

    2015-04-01

    A novel magnetically-separable visible-light-induced photocatalyst, Cu2O/chitosan-Fe3O4 nanocomposite (Cu2O/CS-Fe3O4 NC), was prepared via a facile one-step precipitation-reduction process by using magnetic chitosan chelating copper ions as precursor. The structure and properties of Cu2O/CS-Fe3O4 NCs were characterized by XRD, FT-IR, SEM, HRTEM, SAED, EDS, BET, VSM, XPS and UV-vis/DRS. The photocatalytic activity of Cu2O/CS-Fe3O4 NCs was evaluated by decolorization of reactive brilliant red X-3B (X-3B) under visible light irradiation. The characterization results indicated that Cu2O/CS-Fe3O4 NCs exhibited relatively large specific surface areas and special dimodal pore structure because Cu2O was wrapped in chitosan matrix embedded with Fe3O4 nanoparticles. The tight combination of magnetic Fe3O4 and semiconductor Cu2O through chitosan made the nanocomposites show good superparamagnetism and photocatalytic activity. It was found that X-3B could be decolorized more efficiently in acidic media than in neutral or alkaline media. The decolorization of X-3B was ascribed to the synergistic effect of photocatalysis and adsorption. Cu2O/CS-Fe3O4 NCs could be easily separated from the solution by an external magnet, and the decolorization rates of X-3B were still above 87% after five reaction cycles, indicating that Cu2O/CS-Fe3O4 NCs had excellent reusability and stability.

  5. Response Time Measurements of the NIF DANTE XRD-31 X-Ray Diodes (Pre-print)

    SciTech Connect

    Don Pellinen and Michael Griffin

    2009-01-23

    The XRD-31 is a fast, windowless X-ray vacuum photodiode developed by EG&G. It is currently the primary fast X-ray detector used to diagnose the X-rays on NIF and OMEGA on the multichannel DANTE spectrometer. The XRD-31 has a dynamic range of less than 1e-12 amps to more than 10 amps. A technique is described to measure the impulse response of the diodes to a 150 fs pulse of 200 nm laser light and a method to calculate the “risetime” for a square pulse and compare it with the computed electron transit time from the photocathode to the anode. Measured response time for 5 XRD-31s assembled in early 2004 was 149.7 ps +-2.75 ps.

  6. Characterization of crystallite morphology for doped strontium fluoride nanophosphors by TEM and XRD

    NASA Astrophysics Data System (ADS)

    O'Connell, J. H.; Lee, M. E.; Yagoub, M. Y. A.; Swart, H. C.; Coetsee, E.

    2016-01-01

    Crystallite morphology for Eu-doped and undoped SrF2 nanophosphors have been determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The values for average crystallite size obtained by the application of the Scherrer equation and the full width at half maximum (FWHM) values for XRD peaks are compared to the results obtained using the hollow cone dark field (HCDF) TEM imaging technique. In the case of the TEM analysis, a bimodal crystallite size distribution was revealed with one of the distributions having a measured range of crystallite sizes which was in good agreement with the XRD data. HCDF in combination with FIB specimen preparation was found to be a promising technique for the determination of crystallite size distributions in nanophosphors which might facilitate a better understanding of their scintillation properties.

  7. Data acquisition and control software for XRD beamline at Indus-2

    SciTech Connect

    Kane, Sanjeev R.; Garg, C. K.; Sinha, A. K.

    2010-06-23

    X-ray diffraction (XRD) beamline is under commissioning on Indus-2 synchrotron radiation facility. The experimental setup of XRD beamline consists of a six-circle diffractometer and various detector systems such as scintillation detector, ionization chamber and image plate. The diffractometer can be controlled via EIA232 serial interface or Ethernet. Standard data acquisition software with a graphical user interface has been developed using LabVIEW. A firm safety and error handling scheme is implemented for failsafe operation of the experimental station. This paper describes in detail the data acquisition and control software for the experimental station.

  8. Al(OH)3 facilitated synthesis of water-soluble, magnetic, radiolabelled and fluorescent hydroxyapatite nanoparticles† †Electronic supplementary information (ESI) available: Conjugation of NPs with dyes, radiolabelling for NPs, NMR spectra, XRD, IR, zeta potential, DLS size distribution, TEM images and TGA data of NPs, fluorescent images of NPs. See DOI: 10.1039/c5cc02259b Click here for additional data file.

    PubMed Central

    Cui, X.; Zhou, D.; Yan, Y.; Zhang, W.; Djanashvili, K.; Mathe, D.; Veres, D. S.; Szigeti, K.

    2015-01-01

    Magnetic and fluorescent hydroxyapatite nanoparticles were synthesised using Al(OH)3-stabilised MnFe2O4 or Fe3O4 nanoparticles as precursors. They were readily and efficiently radiolabelled with 18F. Bisphosphonate polyethylene glycol polymers were utilised to endow the nanoparticles with excellent colloidal stability in water and to incorporate cyclam for high affinity labelling with 64Cu. PMID:25960059

  9. Nickel oxide reduction studied by environmental TEM and in situ XRD Q. Jeangros1

    E-print Network

    Dunin-Borkowski, Rafal E.

    Nickel oxide reduction studied by environmental TEM and in situ XRD Q. Jeangros1 , T.W. Hansen2 , J, Switzerland quentin.jeangros@epfl.ch Keywords: Environmental TEM, Nickel Oxide, Reduction Nickel oxide reduction and subsequent Ni behaviour under H2 is of practical importance in the field of solid oxide fuel

  10. A Simple Combustion Synthesis and Optical Studies of Magnetic Zn1-xNi(x)Fe2O4 Nanostructures for Photoelectrochemical Applications.

    PubMed

    Manikandan, A; Antony, S Arul; Sridhar, R; Ramakrishna, Seeram; Bououdina, M

    2015-07-01

    Ni-doped ZnFe2O4 (Ni(X)Zn1-x,Fe2O4; x = 0.0 to 0.5) nanoparticles were synthesized by simple microwave combustion method. The X-ray diffraction (XRD) confirms that all compositions crystallize with cubic spinel ZnFe2O4. The lattice parameter decreases with increase in Ni content resulting in the reduction of lattice strain. High resolution scanning electron microscope (HR-SEM) and transmission electron microscope (HR-TEM) images revealed that the as-prepared samples are crystalline with particle size distribution in 42-50 nm range. Optical properties were determined by UV-Visible diffuse reflectance (DRS) and photoluminescence (PL) spectroscopy respectively. The saturation magnetization (Ms) shows the superparamagnetic nature of the sample for x = 0.0-0.2, whereas for x = 0.3-0.5, it shows ferromagnetic nature. The Ms value is 1.638 emu/g for pure ZnFe2O4 sample and it increases with increase in Ni content. Photoelectrochemical (PEC) measurements showed a significant increase of photocurrent density with increase in the Ni-dopant, and 0.5% Ni-doped ZnFe2O4 sample was found to show the better photoresponse than the other doping concentrations. PMID:26373061

  11. Highly ordered magnetic mesoporous silicas for effective elimination of carbon monoxide

    SciTech Connect

    Lee, Jiho; Ho Chang, Jeong

    2012-04-15

    Catalysts based on crystalline nanoparticles of Fe metal supported on mesoporous silica have been developed. The synthetic process involves hydrogen reduction processing for high abundant Fe metal nanoparticles within the mesopores, in which impregnated Fe salt in the inner nanopores of mesoporous silica is thermally treated under hydrogen at 500 Degree-Sign C. Detailed characterization was achieved by XRD, XPS, BET, and HR-TEM techniques. The catalytic efficiency was demonstrated as a function of the used amounts and reaction time. The results show that more than 90% of the carbon monoxide was eliminated at room temperature during a period 80 min with 0.5 g of catalyst. - Graphical abstract: Strategy for the preparation of highly abundant Fe nanoparticle embedded MS catalyst by hydrogen reduction process and HR-TEM images of cross-sectional and top view. Highlights: Black-Right-Pointing-Pointer MS based heterogeneous catalyst with Fe nanoparticles were demonstrated for CO elimination. Black-Right-Pointing-Pointer Highly Fe nanoparticle embedded MS catalyst prepared by hydrogen reduction process. Black-Right-Pointing-Pointer Systematic characterization was achieved by XRD, XPS, BET, and HR-TEM analyses. Black-Right-Pointing-Pointer More than 90% of the CO was eliminated at RT during 80 min with 0.5 g of catalyst.

  12. An HRTEM investigation of the metastable low-temperature silica phase opal-CT in cherts and porcelanites from the Monterey Formation, CA

    SciTech Connect

    Cady, S.L.; Wenk, H.R. )

    1992-01-01

    High resolution transmission electron microscopy (HRTEM) is used to investigate the metastable low-temperature silica phase opal-CT in cherts and porcelanites from the Miocene Monterey Formation of California. Low-dose imaging techniques developed to image highly beam sensitive proteins were used in this study and have resulted in good phase contrast images of this hydrous silica phase. Detailed X-ray powder diffraction studies of stratigraphically equivalent rocks along the Santa Barbara coast indicate that the primary d-spacing of newly formed opal-CT differs in rocks with different ratios of silica and detrital minerals. Opal-CT forms progressively later and with a smaller primary d-spacing in rocks with increasing amounts of detrital minerals. In siliceous cherts opal-CT occurs as long needles that most often form dense spherulitic fiber bundles which are randomly dispersed within the rock matrix. The random orientation of fiber bundle nucleation centers does not appear to be associated with any obvious nucleation site, unlike the length-slow opal-CT fibers known as lussatite. Opal-CT needles produce optical diffractogram patterns that are compatible with tridymite and crystobalite. Streaking in the diffraction pattern of individual needles is attributed to a high density of planar defects parallel to their length. Planar defects are not as abundant in opal-CT needles formed in detrital-rich rocks suggesting the rapid growth of opal-CT in highly siliceous environments results in a greater proportion of stacking disorder in the needles. HRTEM provides a method for investigating the development of the microstructure of opal-CT during diagenesis.

  13. Morphology and Chemical Composition of soot particles emitted by Wood-burning Cook-Stoves: a HRTEM, XPS and Elastic backscattering Studies.

    NASA Astrophysics Data System (ADS)

    Carabali-Sandoval, G. A., Sr.; Castro, T.; Peralta, O.; De la Cruz, W.; Días, J.; Amelines, O.; Rivera-Hernández, M.; Varela, A.; Muñoz-Muñoz, F.; Policroniades, R.; Murillo, G.; Moreno, E.

    2014-12-01

    The morphology, microstructure and the chemical composition on surface of soot particles were studied by using high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and elastic backscattering spectrometry. In order to obtain freshly soot particles emitted by home-made wood-burning cook stoves, copper grids for Transmission Electron Microscope (TEM) were placed on the last two of an 8-stages MOUDI cascade impactor. The analysis of HRTEM micrographs revealed the nanostructure and the particle size of soot particles. The XPS survey spectra show a large carbon peak around 285 eV and the oxygen signal at 533 eV. Some differences observed in the carbon/oxygen (C/O) ratio of the particles probably depend on the combustion process efficiency of each cook-stove analyzed. The C-1s XPS spectra show an asymmetric broad peak and other with low intensity that corresponds to sp2 and sp3hybridization, which were fitted with a convolution using Gaussian functions. Elastic backscattering technique allows a chemical elemental analysis of samples and confirms the presence of C, O and Si observed by XPS. Additionally, the morphological properties of soot aggregates were analyzed calculating the border-based fractal dimension (Df). Particles exhibit complex shapes with high values of Df. Also, real-time absorption (?abs) and scattering (?sct) coefficients of fine (with aerodynamic diameter < 2.5 µm) soot particles were measured. The trend in ?abs and ?sct indicate that the cooking process has two important combustion stages which varied in its flaming strength, being vigorous in the first stage and soft in the second one.

  14. XRD, SEM and infrared study into the intercalation of sodium hexadecyl sulfate (SHS) into hydrocalumite.

    PubMed

    Zhang, Ping; Wang, Tianqi; Zhang, Longlong; Wu, Daishe; Frost, Ray L

    2015-12-01

    Hydrocalumite (CaAl-LDH-Cl) interacted with a natural anionic surfactant, sodium hexadecyl sulfate (SHS), was performed using an intercalation method. To understand the intercalation behavior and characterize the resulting products, powder X-ray diffraction (XRD), scan electron microscopy (SEM) and mid-infrared (MIR) spectroscopy combined with near-infrared (NIR) spectroscopy technique were used. The XRD analysis indicated that SHS was intercalated into CaAl-LDH-Cl successfully, resulting in an expansion of the interlayer (from 0.78 nm to 2.74 nm). The bands of C-H stretching vibrations of SHS were observed in the near-infrared spectra, which indicated that the resulting products were indeed CaAl-LDH-SHS. In addition, the bands of water stretching vibrations and OH groups shifted to higher wavenumbers when SHS was intercalated into CaAl-LDH-Cl interlayer space. PMID:26163791

  15. Applying high resolution SyXRD analysis on sulfate attacked concrete field samples

    SciTech Connect

    Stroh, J.; Schlegel, M.-C.; Irassar, E.F.; Meng, B.; Emmerling, F.

    2014-12-15

    High resolution synchrotron X-ray diffraction (SyXRD) was applied for a microstructural profile analysis of concrete deterioration after sulfate attack. The cement matrices consist of ordinary Portland cement and different amounts of supplementary cementitious materials, such as fly ash, natural pozzolana and granulated blast furnace slag. The changes of the phase composition were determined along the direction of sulfate ingress. This approach allows the identification of reaction fronts and zones of different phase compositions and conclusions about the mechanisms of sulfate attack. Two reaction fronts were localized in the initial 4 mm from the sample surface. The mechanism of deterioration caused by the exposition in the sulfate-bearing soil is discussed. SyXRD is shown to be a reliable method for investigation of cementitious materials with aggregates embedded in natural environments.

  16. Lattice Expansion of LSCF-6428 Cathodes Measured by In-situ XRD during SOFC Operation

    SciTech Connect

    Hardy, John S.; Templeton, Jared W.; Edwards, Danny J.; Lu, Zigui; Stevenson, Jeffry W.

    2012-01-03

    A new capability has been developed for analyzing solid oxide fuel cells (SOFCs). This paper describes the initial results of in-situ x-ray diffraction (XRD) of the cathode on an operating anode-supported solid oxide fuel cell. It has been demonstrated that XRD measurements of the cathode can be performed simultaneously with electrochemical measurements of cell performance or electrochemical impedance spectroscopy (EIS). While improvements to the technique are still to be made, the XRD pattern of a lanthanum strontium cobalt ferrite (LSCF) cathode with the composition La0.6Sr0.4Co0.2Fe0.8O3-? (LSCF-6428) was found to continually but gradually change over the course of more than 60 hours of operation in air under typical SOFC operating conditions. It was determined that the most significant change was a gradual increase in the cubic lattice parameters of the LSCF from 3.92502 Å (as determined from the integration of the first 20 hours of XRD patterns) to 3.92650 Å (from the integration of the last 20 hours). This analysis also revealed that there were several peaks from unidentified minor phases that increased in intensity over this timeframe. After a temporary loss of airflow early in the test, the cell generated between 225 and 250 mW/cm2 for the remainder of the test. A large low frequency arc in the impedance spectra suggests the cell performance was gas diffusion limited and that there is room for improvement in air delivery to the cell.

  17. Synchronizing flash-melting in a diamond cell with synchrotron X ray diffraction (XRD)

    NASA Astrophysics Data System (ADS)

    Karandikar, Amol; Boehler, Reinhard; Meng, Yue; Rod, Eric; Shen, Guoyin

    2013-06-01

    The major challenges in measuring melting temperatures in laser heated diamond cells are sample instability, thermal runaway and chemical reactions. To circumvent these problems, we developed a ``flash heating'' method using a modulated CW fiber laser and fast X ray detection capability at APS (Pilatus 1M detector). As an example, Pt spheres of 5 micron diameter were loaded in a single crystal sapphire encapsulation in the diamond cell at 65 GPa and heated in a single flash heating event for 20 ms to reach a desired temperature. A CCD spectrometer and the Pilatus were synchronized to measure the temperature and the XRD signal, respectively, when the sample reached the thermal steady state. Each successive flash heating was done at a higher temperature. The integrated XRD pattern, collected during and after (300 K) each heating, showed no chemical reaction up to 3639 K, the highest temperature reached in the experiment. Pt111 and 200 peak intensity variation showed gradual recrystalization and complete diminishing at about 3600 K, indicating melting. Thus, synchronized flash heating with novel sample encapsulation circumvents previous notorious problems and enables accurate melting temperature measurement in the diamond cell using synchrotron XRD probe. Affiliation 2: Geowissenschaeften, Goethe-Universitaet, Altenhoeferallee 1, D-60438 Frankfurt a.M., Germany.

  18. XRD, Photoluminescence and Optical Absorption Investigations of Cobalt-doped ZnO

    SciTech Connect

    Sujinnapram, Supphadate; Onreabroy, Wandee; Nantawisarakul, Tuangrak

    2009-07-07

    Zn{sub 1-x}Co{sub x}O(with x = 0, 0.01, 0.10 and 0.20) were synthesized by solid-state reaction method sintered at 600 deg. C for 12 hours. The samples were studied by X-ray diffraction (XRD), optical absorption (UV-Vis) and Photoluminescence (PL). Structural analysis by Rietveld method using XRD showed that the peaks of secondary phase Co{sub 3}O{sub 4} with a cubic structure were visible in the high-doped sample (x = 0.1, 0.2), besides the main peaks of wurtzite-like structure the same as that of ZnO. Shift of the XRD peaks proved the incorporation of Co{sup 2+} into the ZnO lattice. The band gap energy decreased from 3.18 to 3.14 eV with the increasing of cobalt concentration. PL spectra at room temperature showed the blue emission with the peak around 412 nm. In addition, the intensity of the blue emission decreased upon increasing the Co concentration, which indicated their high structural, defects and optical quality in the ZnO.

  19. Magnetic

    NASA Astrophysics Data System (ADS)

    Aboud, Essam; El-Masry, Nabil; Qaddah, Atef; Alqahtani, Faisal; Moufti, Mohammed R. H.

    2015-06-01

    The Rahat volcanic field represents one of the widely distributed Cenozoic volcanic fields across the western regions of the Arabian Peninsula. Its human significance stems from the fact that its northern fringes, where the historical eruption of 1256 A.D. took place, are very close to the holy city of Al-Madinah Al-Monawarah. In the present work, we analyzed aeromagnetic data from the northern part of Rahat volcanic field as well as carried out a ground gravity survey. A joint interpretation and inversion of gravity and magnetic data were used to estimate the thickness of the lava flows, delineate the subsurface structures of the study area, and estimate the depth to basement using various geophysical methods, such as Tilt Derivative, Euler Deconvolution and 2D modeling inversion. Results indicated that the thickness of the lava flows in the study area ranges between 100 m (above Sea Level) at the eastern and western boundaries of Rahat Volcanic field and getting deeper at the middle as 300-500 m. It also showed that, major structural trend is in the NW direction (Red Sea trend) with some minor trends in EW direction.

  20. Carbon encapsulated magnetic nanoparticles for biomedical applications: thermal stability studies.

    PubMed

    Bystrzejewski, Micha?; Cudzi?o, Stanis?aw; Huczko, Andrzej; Lange, Hubert; Soucy, Gervais; Cota-Sanchez, German; Kaszuwara, Waldemar

    2007-11-01

    Carbon encapsulated magnetic nanoparticles may find many prospective biomedical applications, e.g., in drug and gene delivery systems, disease detection, cancer therapy, rapid toxic cleaning, biochemical sensing, and magnetic resonance imaging. Each of these applications hinges on the relationship between magnetic fields and biological systems. Herein we present the results on the thermal stability of carbon encapsulated magnetic nanoparticles. The products were synthesized by using induction radio frequency (RF) thermal plasma. Phase composition and morphology were studied by powder X-ray diffraction and HRTEM, respectively. Thermal stability was investigated by thermogravimetry and differential thermal analyses. Carbon nanostructures were thermally stable up to 500 K. PMID:17855165

  1. Fabrication of hybrid magnetic Sr5xBa3x(PO4)3(OH)/Fe3O4 nanorod and its highly efficient adsorption performance for acid fuchsin dye

    NASA Astrophysics Data System (ADS)

    Yin, Xiaoju; Zhang, Fan; Zhang, Weihua

    2015-12-01

    The hybrid magnetic Sr5xBa3x(PO4)3(OH)/Fe3O4 (SBPF) nanorod was prepared and characterized using different techniques, such as SEM, EDS, TEM, SAED, HRTEM, XRD, and FT-IR. Adsorption studies of acid fuchsin (AF) from aqueous solution with respect to the pH, temperature, time, initial dye concentration, and sorbent dosage were investigated. The Freundlich adsorption model was applied to describe the equilibrium isotherms. The maximal AF uptake by SBPF was 1590 mg/g in the test. Kinetics parameters of the adsorption process indicated that it followed the pseudo-second order equation, and the maximum sorption capacity calculated from the pseudo-second-order rate equation was 909 mg/g which was close to the experimental value. Adsorption thermodynamics study indicated the spontaneous nature and exothermic of the adsorption process. The removal of AF was attributed to the hydrogen bond and ionic interactions. Moreover, SBPF was easily recovered, and the adsorption capacity was approximately 97.7% of the initial saturation adsorption capacity after being used five times.

  2. XRD, lead equivalent and UV-VIS properties study of Ce and Pr lead silicate glasses

    SciTech Connect

    Alias, Nor Hayati Abdullah, Wan Shafie Wan Isa, Norriza Mohd Isa, Muhammad Jamal Md Zali, Nurazila Mat; Abdullah, Nuhaslinda Ee; Muhammad, Azali

    2014-02-12

    In this work, Cerium (Ce) and Praseodymium (Pr) containing lead silicate glasses were produced with 2 different molar ratios low (0.2 wt%) and high (0.4wt%). These types of glasses can satisfy the characteristics required for radiation shielding glasses and minimize the lead composition in glass. The radiation shielding properties of the synthesized glasses is explained in the form of lead equivalent study. The XRD diffraction and UV-VIS analysis were performed to observe the structural changes of the synthesis glasses at 1.5 Gy gamma radiation exposures.

  3. The XRD Amorphous Component in John Klein Drill Fines at Yellowknife Bay, Gale Crater, Mars

    NASA Technical Reports Server (NTRS)

    Morris, Richard V.; Ming,, Douglas W.; Blake, David; Vaniman, David; Bish, David L; Chipera, Steve; Downs, Robert; Morrison, Shaunna; Gellert, Ralf; Campbell, Iain; Treiman, Alan H.; Achilles, Cherie; Bristow, Thomas; Crisp, Joy A.; McAdam, Amy; Archer, Paul Douglas; Sutter, Brad; Rampe, Elizabeth B.

    2013-01-01

    Drill fines of mudstone (targets John Klein and Cumberland) from the Sheepbed unit at Yel-lowknife Bay were analyzed by MSL payload elements including the Chemistry and Mineralogy (CheMin), APXS (Alpha Particle X-Ray Spectrometer), and Sample Analysis at Mars (SAM) instruments. CheMin XRD results show a variety of crystalline phases including feldspar, pyroxene, olivine, oxides, oxyhydroxides, sulfates, sulfides, a tri-octahedral smectite, and XRD amorphous material. The drill fines are distinctly different from corresponding analyses of the global soil (target Rocknest) in that the mudstone samples contained detectable phyllosilicate. Here we focus on John Klein and combine CheMin and APXS data to calculate the chemical composition and concentration of the amorphous component. The chemical composition of the amorphous plus smectite component for John Klein was calculated by subtracting the abundance-weighted chemical composition of the individual XRD crystalline components from the bulk composition of John Kline as measured by APXS. The chemical composition of individual crystalline components was determined either by stoichiometry (e.g., hematite and magnetite) or from their unit cell parameters (e.g., feldspar, olivine, and pyroxene). The chemical composition of the amorphous + smectite component (approx 71 wt.% of bulk sample) and bulk chemical composition are similar. In order to calculate the chemical composition of the amorphous component, a chemical composition for the tri-octahedral smectite must be assumed. We selected two tri-octahedral smectites with very different MgO/(FeO + Fe2O3) ratios (34 and 1.3 for SapCa1 and Griffithite, respectively). Relative to bulk sample, the concentration of amorphous and smectite components are 40 and 29 wt.% for SapCa1 and 33 and 36 wt.% for Griffithite. The amount of smectite was calculated by requiring the MgO concentration to be approx 0 wt.% in the amorphous component. Griffithite is the preferred smectite because the position of its 021 diffraction peak is similar to that reported for John Klein. In both cases, the amorphous component has low SiO2 and MgO and high FeO + Fe2O3, P2O5, and SO3 concentrations relative to bulk sample. The chemical composition of the bulk drill fines and XRD crystalline, smectite, and amorphous components implies alteration of an initially basaltic material under near neutral conditions (not acid sulfate), with the sulfate incorporated later as veins of CaSO4 injected into the mudstone.

  4. IN-SITU XRD OF OPERATING LSFC CATHODES: DEVELOPMENT OF A NEW ANALYTICAL CAPABILITY

    SciTech Connect

    Hardy, John S.; Templeton, Jared W.; Stevenson, Jeffry W.

    2012-11-19

    A solid oxide fuel cell (SOFC) research capability has been developed that facilitates measuring the electrochemical performance of an operating SOFC while simultaneously performing x-ray diffraction on its cathode. The evolution of this research tool’s development is discussed together with a description of the instrumentation used for in-situ x-ray diffraction (XRD) measurements of operating SOFC cathodes. The challenges that were overcome in the process of developing this capability, which included seals and cathode current collectors, are described together with the solutions that are presently being applied to mitigate them.

  5. A mathematical method for XRD pattern interpretation in clay containing nano composites

    NASA Astrophysics Data System (ADS)

    Khederlou, Kh.; Bagheri, R.; Shojaei, A.

    2014-11-01

    X-ray diffraction and rheological measurements were used to characterize nanoparticle dispersion in LDPE/LLDPE/nanoclay hybrid nanocomposites. XRD patterns were interpreted with a novel distribution formula and rheological measurements were used to confirm the results. Results of these two methods indicated that increasing clay in all the prepared nanocomposites exhibited a significant improvement in filler-matrix interaction because of increasing the probability of polymer diffusion but further exfoliation need more compatibilizing situations. It seems that this mathematical method could be used for predicting the overall change in clay gallery d-spacing and the extent of intercalation-exfoliation of nanoclay in these systems.

  6. Analytical electron microscopy of Mg-SiO smokes - A comparison with infrared and XRD studies

    NASA Technical Reports Server (NTRS)

    Rietmeijer, F. J. M.; Nuth, J. A.; Mackinnon, I. D. R.

    1986-01-01

    Analytical electron microscopy conducted for Mg-SiO smokes (experimentally obtained from samples previously characterized by IR spectroscopy) indicates that the microcrystallinity content of unannealed smokes increases with increased annealing for up to 30 hr. The growth of forsterite microcrystallites in the initially nonstoichiometric smokes may give rise to the contemporaneous growth of the SiO polymorph tridymite and MgO; after 4 hr of annealing, these react to form enstatite. It is suggested that XRD analysis and IR spectroscopy should be conducted in conjunction with detailed analytical electron microscopy for the detection of emerging crystallinity in vapor-phase condensates.

  7. Luminescence and magnetic properties of novel nanoparticle-sheathed 3D Micro-Architectures of Fe0.5R0.5(MoO4)1.5:Ln3+ (R = Gd3+, La3+), (Ln = Eu, Tb, Dy) for bifunctional application

    NASA Astrophysics Data System (ADS)

    Krishnan, Rajagopalan; Thirumalai, Jagannathan; Kathiravan, Arunkumar

    2015-01-01

    For the first time, we report the successful synthesis of novel nanoparticle-sheathed bipyramid-like and almond-like Fe0.5R0.5(MoO4)1.5:Ln3+ (R = Gd3+, La3+), (Ln = Eu, Tb, Dy) 3D hierarchical microstructures through a simple disodium ethylenediaminetetraacetic acid (Na2EDTA) facilitated hydrothermal method. Interestingly, time-dependent experiments confirm that the assembly-disassembly process is responsible for the formation of self-aggregated 3D architectures via Ostwald ripening phenomena. The resultant products are characterized by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), photoluminescence (PL), and magnetic measurements. The growth and formation mechanisms of the self-assembled 3D micro structures are discussed in detail. To confirm the presence of all the elements in the microstructure, the energy loss induced by the K, L shell electron ionization is observed in order to map the Fe, Gd, Mo, O, and Eu components. The photo luminescence properties of Fe0.5R0.5(MoO4)1.5 doped with Eu3+, Tb3+, Dy3+ are investigated. The room temperature and low temperature magnetic properties suggest that the interaction between the local-fields introduced by the magnetic Fe3+ ions and the R3+ (La, Gd) ions in the dodecahedral sites determine the magnetism in Fe0.5R0.5(MoO4)1.5:Eu3+. This work provides a new approach to synthesizing the novel Fe0.5R0.5(MoO4)1.5:Ln3+ for bi-functional magnetic and luminescence applications.

  8. XRD and FTIR structural investigation of gadolinium-zinc-borate glass ceramics

    SciTech Connect

    Borodi, G.; Pascuta, P.; Dan, V.; Pop, V.; Stefan, R.; Radulescu, D.

    2013-11-13

    X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy measurements have been employed to investigate the (Gd{sub 2}O{sub 3}){sub x}?(B{sub 2}O{sub 3}){sub (60?x)}?(ZnO){sub 40} glass ceramics system, with 0 ? x ? 15 mol%. After heat treatment applied at 860 °C for 2 h, some structural changes were observed and new crystalline phases appeared in the structure of the samples. In these glass ceramics four crystalline phases were identified using powder diffraction files (PDF 2), namely ZnB{sub 4}O{sub 7}, Zn{sub 4}O(B{sub 6}O{sub 12}), Zn{sub 3}(BO{sub 3}){sub 2} and GdBO{sub 3}. From the XRD data, the average unit-cell parameter and the quantitative ratio of the crystallographic phases in the studied samples were evaluated. FTIR data revealed that the BO{sub 3}, BO{sub 4} and ZnO{sub 4} are the main structural units of these glass ceramics network. The compositional dependence of the different structural units which appear in the studied samples was followed.

  9. Hydrometallurgical Extraction of Zinc and Copper A 57Fe-Mössbauer and XRD Approach

    NASA Astrophysics Data System (ADS)

    Mulaba-Bafubiandi, A. F.; Waanders, F. B.

    2005-02-01

    The most commonly used route in the hydrometallurgical extraction of zinc and copper from a sulphide ore is the concentrate roast leach electro winning process. In the present investigation a zinc copper ore from the Maranda mine, located in the Murchison Greenstone Belt, South Africa, containing sphalerite (ZnS) and chalcopyrite (CuFeS2), was studied. The 57Fe-Mössbauer spectrum of the concentrate yielded pyrite, chalcopyrite and clinochlore, consistent with XRD data. Optimal roasting conditions were found to be 900°C for 3 h and the calcine produced contained according to X-ray diffractometry equal amounts of franklinite (ZnFe2O4) and zinc oxide (ZnO) and half the amount of willemite (Zn2SiO4). The Mössbauer spectrum showed predominantly franklinite (59%), hematite (6%) and other Zn- or Cu-depleted ferrites (35%). The latter could not be detected by XRD analyses as peak overlapping with other species occurred. Leaching was done with HCl, H2SO4 and HNO3, to determine which process would result in maximum recovery of Zn and Cu. More than 80% of both were recovered by using either one of the three techniques. From the residue of the leaching, the Fe-compounds were precipitated and <1% of the Zn and Cu was not recovered.

  10. Trace elemental analysis of Indian natural moonstone gems by PIXE and XRD techniques.

    PubMed

    Venkateswara Rao, R; Venkateswarulu, P; Kasipathi, C; Sivajyothi, S

    2013-12-01

    A selected number of Indian Eastern Ghats natural moonstone gems were studied with a powerful nuclear analytical and non-destructive Proton Induced X-ray Emission (PIXE) technique. Thirteen elements, including V, Co, Ni, Zn, Ga, Ba and Pb, were identified in these moonstones and may be useful in interpreting the various geochemical conditions and the probable cause of their inceptions in the moonstone gemstone matrix. Furthermore, preliminary XRD studies of different moonstone patterns were performed. The PIXE technique is a powerful method for quickly determining the elemental concentration of a substance. A 3MeV proton beam was employed to excite the samples. The chemical constituents of moonstones from parts of the Eastern Ghats geological formations of Andhra Pradesh, India were determined, and gemological studies were performed on those gems. The crystal structure and the lattice parameters of the moonstones were estimated using X-Ray Diffraction studies, trace and minor elements were determined using the PIXE technique, and major compositional elements were confirmed by XRD. In the present work, the usefulness and versatility of the PIXE technique for research in geo-scientific methodology is established. PMID:24055999

  11. An Integrated XRF/XRD Instrument for Mars Exobiology and Geology Experiments

    NASA Technical Reports Server (NTRS)

    Koppel, L. N.; Franco, E. D.; Kerner, J. A.; Fonda, M. L.; Schwartz, D. E.; Marshall, J. R.

    1993-01-01

    By employing an integrated x-ray instrument on a future Mars mission, data obtained will greatly augment those returned by Viking; details characterizing the past and present environment on Mars and those relevant to the possibility of the origin and evolution of life will be acquired. A combined x-ray fluorescence/x-ray diffraction (XRF/XRD) instrument was breadboarded and demonstrated to accommodate important exobiology and geology experiment objectives outlined for MESUR and future Mars missions. Among others, primary objectives for the exploration of Mars include the intense study of local areas on Mars to establish the chemical, mineralogical, and petrological character of different components of the surface material; to determine the distribution, abundance, and sources and sinks of volatile materials, including an assessment of the biologic potential, now and during past epoches; and to establish the global chemical and physical characteristics of the Martian surface. The XRF/XRD breadboard instrument identifies and quantifies soil surface elemental, mineralogical, and petrological characteristics and acquires data necessary to address questions on volatile abundance and distribution. Additionally, the breadboard is able to characterize the biogenic element constituents of soil samples providing information on the biologic potential of the Mars environment. Preliminary breadboard experiments confirmed the fundamental instrument design approach and measurement performance.

  12. Upgrades to the XRD1 beamline optics and endstation at the LNLS

    NASA Astrophysics Data System (ADS)

    Canova, H.; Fontoura, A.; Neuenschwander, R. T.; Diaz, B.; Rodella, C. B.

    2014-03-01

    XRD1 was the first X-ray diffraction beamline to be built at the LNLS and after approximately 12 years of operation it was substantially updated to improve beam stability, increase the reliability of the monochromator movement as well as provide an experimental hutch that would meet the demands of users. The improvements included the construction of an independent concrete slab below the mirror and monochromator to minimize the vibrations originating from the floor. In addition, the installation of new monochromator mechanisms as well as the replacement of the two Si(111) crystals were performed in order to attain higher precision, stability and reproducibility during operation. Moreover, the diffractometer was replaced by a 3-circle heavy duty diffractometer from Newport to collect XRD patterns primarily in capillary geometry. A robotic arm was installed for fast and automated replacement of samples as well as to secure a cryojet or a hot air blower in front of the sample during measurements. In addition, a housing equipped with 24 Mythen detectors was installed at the beamline allowing for extremely fast data acquisition. Another upgrade was the integration of motors and control systems from PXI National Instruments and Galil controllers with Phytron. These systems are crucial for the next upgrade that is underway at the beamline: enabling remote access for users to collect their measurements without the need to travel to the LNLS.

  13. The use of micro-XRD for the study of glaze color decorations

    NASA Astrophysics Data System (ADS)

    Pradell, T.; Molina, G.; Molera, J.; Pla, J.; Labrador, A.

    2013-04-01

    The compounds responsible for the colors and decorations in glass and glazed ceramics include: coloring agents (transition-metal ions), pigments (micro- and nanoprecipitates of compounds that either do not dissolve or recrystallize in the glassy matrix) and opacifiers (microcrystalline compounds with high light scattering capability). Their composition, structure and range of stability are highly dependent not only on the composition but also on the procedures followed to obtain them. Chemical composition of the colorants and crystallites may be obtained by means of SEM-EDX and WDX. Synchrotron radiation micro-X-ray diffraction (SR-micro-XRD) has a small beam size adequate (10 to 50 microns footprint size) to obtain the structural information of crystalline compounds and high brilliance, optimal for determining the crystallites even when present in low amounts. In addition, in glass decorations the crystallites often appear forming thin layers (from 10 to 100 micrometers thick) and they show a depth-dependent composition and crystal structure. Their nature and distribution across the glass/glaze decorations gives direct information on the technology of production and stability and may be related to the color and appearance. A selection of glass and glaze coloring agents and decorations are studied by means of SR-micro-XRD and SEM-EDX including: manganese brown, antimony yellow, red copper lusters and cobalt blue. The selection includes Medieval (Islamic, and Hispano Moresque) and Renaissance tin-glazed ceramics from the 10th to the 17th century AD.

  14. HRTEM Study of Oxide Nanoparticles in 16Cr-4Al-2W-0.3Ti-0.3Y2O3 ODS Steel

    SciTech Connect

    Hsiung, L; Fluss, M; Wall, M; Kimura, A

    2009-11-18

    Crystal and interfacial structures of oxide nanoparticles in 16Cr-4Al-2W-0.3Ti-0.3Y{sub 2}O{sub 3} ODS ferritic steel have been examined using high-resolution transmission electron microscopy (HRTEM) techniques. Oxide nanoparticles with a complex-oxide core and an amorphous shell were frequently observed. The crystal structure of complex-oxide core is identified to be mainly monoclinic Y{sub 4}Al{sub 2}O{sub 9} (YAM) oxide compound. Orientation relationships between the oxide and matrix are found to be dependent on the particle size. Large particles (> 20 nm) tend to be incoherent and have a spherical shape, whereas small particles (< 10 nm) tend to be coherent or semi-coherent and have a faceted interface. The observations of partially amorphous nanoparticles lead us to propose three-stage mechanisms to rationalize the formation of oxide nanoparticles containing core/shell structures in as-fabricated ODS steels.

  15. The high - low-p clinoenstatite transition: in situ xrd and ultrasonic study

    NASA Astrophysics Data System (ADS)

    Müller, H. J.; Wunder, B.; Lathe, C.; Schilling, F. R.

    2003-04-01

    Using single-crystal X-ray diffraction analyses in a diamond anvil cell Angel et al. (1992) published the transformation of MgSiO_3 from LCEn to a C2/c-polymorph (HCEn) at around 5.5 - 8.0 GPa and room-T (RT)conditions. This LCEn - HCEn-transition is not quenchable. However, the knowledge of the exact phase boundary positions for the MgSiO_3-transitions is essential as pyroxene is an important component of the Earth's mantle and will significantly influence elastic properties (e.g. v_p, v_s) of the mantle. We determined the HCEn - LCEn-transition by in-situ XRD experiments under high P, T using the multi-anvil appar atus MAX80 at the synchrotron facility HASYLAB, Hamburg. Our preliminary results only represent the minimum P-conditions of the HCEn - LCEn phase boundary, which is approximated by equation P (GPa) = 0.0021T (/C) + 6.06. Nevertheless, our results are in good agreement to data published by Angel & Hugh-Jones (1994). The invariant point defined by the intersection of the HCEn - LCEn equilibrium determined within this study and the OEn - LCEn reaction after Angel &Hugh-Jones (1994) lies at about 7.9 GPa and 875/C. This is in contrast to earlier experimental results of Kanzaki (1991) and Ulmer &Stalder (2001). The samples for the ultrasonic interferometry experiments were prepared by hot-isostatic pressing also using the MAX80. Adjacent XRD ruled out any phase transition during the hip-process. For the ultrasonic measurements one of the six anvils of MAX80 were exchanged by an anvil equipped with lithium niobate p- and s-wave transducers of 33.3 MHz natural frequency (Mueller et al., 2002). Corresponding to the XRD experiments HCEn was formed by increasing the pressure at RT. The velocities of elastic compressional and shear waves were measured under in situ conditions using the classical digital sweep technique. After the phase transition to LCEn as a result of rising the temperature at given pressure the measurements were repeated. The newly developed ultra sonic data transfer function (UDTF) technique, first described by Li (pers. comm.), enabling much faster measurements than the classical method, was used to measure both the elastic wave velocities of LCEn in dependence on pressure at 700/C. To compare the results v_p and v_s were measured at 6.7 GPa and 7.5 GPa using both interferometric techniques. The results demonstrate the correspondence in the limits of less than 1 %.

  16. Coupling XRD, EXAFS, and 13C NMR to study the effect of the carbon stoichiometry on the local structure of UC(1±x).

    PubMed

    Carvajal Nuñez, U; Martel, L; Prieur, D; Lopez Honorato, E; Eloirdi, R; Farnan, I; Vitova, T; Somers, J

    2013-10-01

    A series of uranium carbide samples, prepared by arc melting with a C/U ratio ranging from 0.96 to 1.04, has been studied by X-ray diffraction (XRD), (13)C nuclear magnetic resonance (NMR), and extended X-ray absorption fine structure (EXAFS). XRD determines phase uniqueness and the increase of the lattice parameter versus the carbon content. In contrast, (13)C NMR detects the different carbon environments in the lattice and in this study, clearly identifies the presence of discrete peaks for carbon in the octahedral lattice site in UC and an additional peak associated with excess carbon in hyperstoichiometric samples. Two peaks associated with different levels of carbon deficiency are detected for all hypostoichiometric compositions. More than one carbon environment is always detected by (13)C NMR. This exemplifies the difficulty in obtaining a perfect stoichiometric uranium monocarbide UC(1.00). The (13)C MAS spectra of uranium carbides exhibit the effects resulting from the carbon content on both the broadening of the peaks and on the Knight shift. An abrupt spectral change occurs between hypo- and hyperstoichiometric samples. The results obtained by EXAFS highlight subtle differences between the different stoichiometries, and in the hyperstoichiometric samples, the EXAFS results are consistent with the excess carbon atoms being in the tetrahedral interstitial position. PMID:24063301

  17. Studying Cellulose Fiber Structure by SEM, XRD, NMR and Acid Hydrolysis

    SciTech Connect

    Zhao, Haibo; Kwak, Ja Hun; Zhang, Z. Conrad; Brown, Heather M.; Arey, Bruce W.; Holladay, John E.

    2007-03-21

    Cotton linters were partially hydrolyzed in dilute acid and the morphology of remaining macrofibrils studied with Scanning Electron Microscopy (SEM) under various magnifications. The crystal region (microfibril bundles) in the macrofibrils was not altered by hydrolysis, and only amorphous cellulose was hydrolyzed and leached out from the macrofibrils. The diameter of microfibril bundles was 20-30 nm after the amorphous cellulose was removed by hydrolysis. XRD experiments confirm the unaltered diameter of the microfibrils after hydrolysis. The strong stability of these microfibril bundles in hydrolysis limits both the total sugar monomer yield and the size of nano particles or rods produced in hydrolysis. The large surface potential on the remaining microfibril bundles drives the agglomeration of macrofibrils.

  18. Radiometric, SEM and XRD investigation of the Chituc black sands, southern Danube Delta, Romania.

    PubMed

    Margineanu, R M; Blebea-Apostu, Ana-Maria; Celarel, Aurelia; Gomoiu, Claudia-Mariana; Costea, C; Dumitras, Delia; Ion, Adriana; Duliu, O G

    2014-12-01

    The black sand of the Chituc marine sand bank, northern of the city of Navodari (Romania), presents anomalous high radioactivity. Field measurements recorded in some places dose rate up to 200 nSv/h, significantly overpassing the average value of 44 ± 20 nSv/h along the entire Southern sector of Romanian Black Sea shore. Gamma ray spectrometry performed on both Slanic-Prahova Underground Low Background Laboratory and Geological Institute of Romania Radiometric Facilities showed with clarity the dominance of (228)Ac radioisotope in the 50 microns fraction together with the (226)Ra and traces of (40)K. No significant amount of anthropogenic (137)Cs was identified. Based on radiometric as well as on SEM-EDAX and XRD determinations we come to the conclusion that the evidenced radioactivity could be attributed to both uranium and thorium series in the zircon and monazite fractions and to a lesser extent to potassium in the feldspars. PMID:25181034

  19. Laboratory Detection and Analysis of Organic Compounds in Rocks Using HPLC and XRD Methods

    NASA Technical Reports Server (NTRS)

    Dragoi, D.; Kanik, I.; Bar-Cohen, Y.; Sherrit, S.; Tsapin, A.; Kulleck, J.

    2004-01-01

    In this work we describe an analytical method for determining the presence of organic compounds in rocks, limestone, and other composite materials. Our preliminary laboratory experiments on different rocks/limestone show that the organic component in mineralogical matrices is a minor phase on order of hundreds of ppm and can be better detected using high precision liquid chromatography (HPLC). The matrix, which is the major phase, plays an important role in embedding and protecting the organic molecules from the harsh Martian environment. Some rocks bear significant amounts of amino acids therefore, it is possible to identify these phases using powder x-ray diffraction (XRD) by crystallizing the organic. The method of detection/analysis of organics, in particular amino acids, that have been associated with life will be shown in the next section.

  20. Powder XRD and dielectric studies of gel grown calcium pyrophosphate crystals

    NASA Astrophysics Data System (ADS)

    Parekh, Bharat; Parikh, Ketan; Joshi, Mihir

    2013-06-01

    Formation of calcium pyrophosphate dihydrate (CPPD) crystals in soft tissues such as cartilage, meniscus and synovial tissue leads to CPPD deposition diseases. The appearance of these crystals in the synovial fluid can give rise to an acute arthritic attack with pain and inflammation of the joints, a condition called pseudo-gout. The growth of CPP crystals has been carried out, in the present study, using the single diffusion gel growth technique, which can broadly mimic in vitro the condition in soft tissues. The crystals were characterized by different techniques. The FTIR study revealed the presence of various functional groups. Powder XRD study was also carried out to verify the crystal structure. The dielectric study was carried out at room temperature by applying field of different frequency from 500 Hz to 1 MHz. The dielectric constant, dielectric loss and a.c. resistivity decreased as frequency increased, whereas the a.c. conductivity increased as frequency increased.

  1. Thermal decomposition of dolomite under CO2: insights from TGA and in situ XRD analysis.

    PubMed

    Valverde, Jose Manuel; Perejon, Antonio; Medina, Santiago; Perez-Maqueda, Luis A

    2015-11-28

    Thermal decomposition of dolomite in the presence of CO2 in a calcination environment is investigated by means of in situ X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The in situ XRD results suggest that dolomite decomposes directly at a temperature around 700 °C into MgO and CaO. Immediate carbonation of nascent CaO crystals leads to the formation of calcite as an intermediate product of decomposition. Subsequently, decarbonation of this poorly crystalline calcite occurs when the reaction is thermodynamically favorable and sufficiently fast at a temperature depending on the CO2 partial pressure in the calcination atmosphere. Decarbonation of this dolomitic calcite occurs at a lower temperature than limestone decarbonation due to the relatively low crystallinity of the former. Full decomposition of dolomite leads also to a relatively low crystalline CaO, which exhibits a high reactivity as compared to limestone derived CaO. Under CO2 capture conditions in the Calcium-Looping (CaL) process, MgO grains remain inert yet favor the carbonation reactivity of dolomitic CaO especially in the solid-state diffusion controlled phase. The fundamental mechanism that drives the crystallographic transformation of dolomite in the presence of CO2 is thus responsible for its fast calcination kinetics and the high carbonation reactivity of dolomitic CaO, which makes natural dolomite a potentially advantageous alternative to limestone for CO2 capture in the CaL technology as well as SO2in situ removal in oxy-combustion fluidized bed reactors. PMID:26506285

  2. Reduction of mixed Mn-Zr oxides: in situ XPS and XRD studies.

    PubMed

    Bulavchenko, O A; Vinokurov, Z S; Afonasenko, T N; Tsyrul'nikov, P G; Tsybulya, S V; Saraev, A A; Kaichev, V V

    2015-09-21

    A series of mixed Mn-Zr oxides with different molar ratios Mn/Zr (0.1-9) have been prepared by coprecipitation of manganese and zirconium nitrates and characterized by X-ray diffraction (XRD) and BET methods. It has been found that at concentrations of Mn below 30 at%, the samples are single-phase solid solutions (MnxZr1-xO2-?) based on a ZrO2 structure. X-ray photoelectron spectroscopy (XPS) measurements showed that manganese in these solutions exists mainly in the Mn(4+) state on the surface. An increase in Mn content mostly leads to an increase in the number of Mn cations in the structure of solid solutions; however, a part of the manganese cations form Mn2O3 and Mn3O4 in the crystalline and amorphous states. The reduction of these oxides with hydrogen was studied by a temperature-programmed reduction technique, in situ XRD, and near ambient pressure XPS in the temperature range from 100 to 650 °C. It was shown that the reduction of the solid solutions MnxZr1-xO2-? proceeds via two stages. During the first stage, at temperatures between 100 and 500 °C, the Mn cations incorporated into the solid solutions MnxZr1-xO2-? undergo partial reduction. During the second stage, at temperatures between 500 and 700 °C, Mn cations segregate on the surface of the solid solution. In the samples with more than 30 at% Mn, the reduction of manganese oxides was observed: Mn2O3 ? Mn3O4 ? MnO. PMID:26239114

  3. Highly ordered magnetic mesoporous silicas for effective elimination of carbon monoxide

    NASA Astrophysics Data System (ADS)

    Lee, Jiho; Ho Chang, Jeong

    2012-04-01

    Catalysts based on crystalline nanoparticles of Fe metal supported on mesoporous silica have been developed. The synthetic process involves hydrogen reduction processing for high abundant Fe metal nanoparticles within the mesopores, in which impregnated Fe salt in the inner nanopores of mesoporous silica is thermally treated under hydrogen at 500 °C. Detailed characterization was achieved by XRD, XPS, BET, and HR-TEM techniques. The catalytic efficiency was demonstrated as a function of the used amounts and reaction time. The results show that more than 90% of the carbon monoxide was eliminated at room temperature during a period 80 min with 0.5 g of catalyst.

  4. Evaluation of Rock Powdering Methods to Obtain Fine-grained Samples for CHEMIN, a Combined XRD/XRF Instrument

    NASA Technical Reports Server (NTRS)

    Chipera, S. J.; Vaniman, D. T.; Bish, D. L.; Sarrazin, P.; Feldman, S.; Blake, D. F.; Bearman, G.; Bar-Cohen, Y.

    2004-01-01

    A miniature XRD/XRF (X-ray diffraction / X-ray fluorescence) instrument, CHEMIN, is currently being developed for definitive mineralogic analysis of soils and rocks on Mars. One of the technical issues that must be addressed to enable remote XRD analysis is how best to obtain a representative sample powder for analysis. For powder XRD analyses, it is beneficial to have a fine-grained sample to reduce preferred orientation effects and to provide a statistically significant number of crystallites to the X-ray beam. Although a two-dimensional detector as used in the CHEMIN instrument will produce good results even with poorly prepared powder, the quality of the data will improve and the time required for data collection will be reduced if the sample is fine-grained and randomly oriented. A variety of methods have been proposed for XRD sample preparation. Chipera et al. presented grain size distributions and XRD results from powders generated with an Ultrasonic/Sonic Driller/Corer (USDC) currently being developed at JPL. The USDC was shown to be an effective instrument for sampling rock to produce powder suitable for XRD. In this paper, we compare powder prepared using the USDC with powder obtained with a miniaturized rock crusher developed at JPL and with powder obtained with a rotary tungsten carbide bit to powders obtained from a laboratory bench-scale Retsch mill (provides benchmark mineralogical data). These comparisons will allow assessment of the suitability of these methods for analysis by an XRD/XRF instrument such as CHEMIN.

  5. Data from the Mars Science Laboratory CheMin XRD/XRF Instrument

    NASA Technical Reports Server (NTRS)

    Vaniman, David; Blake, David; Bristow, Tom; DesMarais, David; Achilles, Cherie; Anderson, Robert; Crips, Joy; Morookian, John Michael; Spanovich, Nicole; Vasavada, Ashwin; Yen, Albert; Bish, David; Chipera, Steve; Downs, Robert; Morrison, Shaunna; Farmer, Jack; Grotzinger, John; Stolper, Edward; Ming, Douglas; Morris, Richard; Rampe, Elizabeth; Treiman, Allan; Sarrazin, Philippe

    2013-01-01

    The CheMin instrument on the Mars Science Laboratory (MSL) rover Curiosity uses a Co tube source and a CCD detector to acquire mineralogy from diffracted primary X-rays and chemical information from fluoresced X-rays. CheMin has been operating at the MSL Gale Crater field site since August 5, 2012 and has provided the first X-ray diffraction (XRD) analyses in situ on a body beyond Earth. Data from the first sample collected, the Rocknest eolian soil, identify a basaltic mineral suite, predominantly plagioclase (approx.An50), forsteritic olivine (approx.Fo58), augite and pigeonite, consistent with expectation that detrital grains on Mars would reflect widespread basaltic sources. Minor phases (each <2 wt% of the crystalline component) include sanidine, magnetite, quartz, anhydrite, hematite and ilmenite. Significantly, about a third of the sample is amorphous or poorly ordered in XRD. This amorphous component is attested to by a broad rise in background centered at approx.27deg 2(theta) (Co K(alpha)) and may include volcanic glass, impact glass, and poorly crystalline phases including iron oxyhydroxides; a rise at lower 2(theta) may indicate allophane or hisingerite. Constraints from phase chemistry of the crystalline components, compared with a Rocknest bulk composition from the APXS instrument on Curiosity, indicate that in sum the amorphous or poorly crystalline components are relatively Si, Al, Mg-poor and enriched in Ti, Cr, Fe, K, P, S, and Cl. All of the identified crystalline phases are volatile-free; H2O, SO2 and CO2 volatile releases from a split of this sample analyzed by the SAM instrument on Curiosity are associated with the amorphous or poorly ordered materials. The Rocknest eolian soil may be a mixture of local detritus, mostly crystalline, with a regional or global set of dominantly amorphous or poorly ordered components. The Rocknest sample was targeted by MSL for "first time analysis" to demonstrate that a loose deposit could be scooped, sieved to <150 microns, and delivered to instruments in the body of the rover. A drilled sample of sediment in outcrop is anticipated. At the time of writing this abstract, promising outcrops are in range and this talk will provide an update on data collected with the CheMin instrument.

  6. EPR, SEM and XRD investigation of ornamental limestone and marbles from some renowned Romanian quarries.

    NASA Astrophysics Data System (ADS)

    Covaci, D.; Costea, C.; Dumitras, D.; Duliu, O. G.

    2012-04-01

    Ornamental limestone and marble samples were collected and analysed by means of Electron Paramagnetic Resonance (EPR), Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD), in order to evidence any systematic peculiarities able to be used in further provenance studies as well as to get more detailed information regarding geochemistry and mineralogy of three of the most important deposits from Romania. In this respect, 20 samples of limestone (Arnota quarry, Capatani Mountains and Mateias South quarry, Iezer Mountains) and 9 of calci-dolomitic marble (Porumbacu de Sus quarry, Fagaras Mountains) were collected over a significant sampling area. EPR spectroscopy, primarily used to asset the degree of homogeneity of considered samples, evidenced, for both Arnota and Mateias South limestone, the presence of a typical six hyperfine lines spectrum of Mn2+ ions in calcite but no traces of Fe ferromagnetic clusters. A more careful investigation has showed that although within the same quarry, there were no significant differences regarding EPR spectra, the resonance lines were systematic narrower in the case of Mateias South samples which suggested a lower content of divalent manganese ions. The Porumbacu calci-dolomitic marble, presented a more intricate Mn2+ spectrum, consisting of a superposition of typical dolomitic and calcitic spectra. Again, the EPR spectra were almost identical, attesting, as in the previous cases, a relative uniform distribution of paramagnetic Mn2+ ions within quarry. In the case of SEM, scattered, back scattered and absorbed electron modes were used to visualise the mineral formations on the sample surfaces while an EDAX quantitative analysis was used to determine the content of the most abundant elements. Although, at a first inspection, both groups of limestone looked almost similar, displaying a great variety of randomly orientated micro-crystalline agglomeration, only in the case of Arnota samples, we have noticed the presence of some micron size graphite inclusions, potential proxies for further provenance studies. The Porumbacu South marble showed a different pattern, characterized by a more uniform crystallite distribution, all of them presenting almost perfect cleaving surfaces. EDAX results evidenced, excepting the dominant Ca and Mg (the last one in the case of Porumbacu de Sus marble), the presence, in small quantities, of some other element such as Fe, Ni, Cu and Zn whose content represent also a good provenance proxy. XRD investigation evidenced not only of the dominant calcite and dolomite mineral phases, but also other minor mineral fraction, whose presence could be well related to the content of mentioned trace elements. Principal Component and Cluster Analysis, finally used to classify all investigated samples, allowed us to group them in three cluster in accordance with their provenance.

  7. XRD Analysis of Cement Paste Samples Exposed to the Simulated Environment of a Deep Repository - 12239

    SciTech Connect

    Ferreira, Eduardo G.A.; Marumo, Julio T.; Vicente, Roberto; Gobbo, Luciano

    2012-07-01

    Portland cement materials are widely used as engineered barriers in repositories for radioactive waste. The capacity of such barriers to avoid the disposed of radionuclides to entering the biosphere in the long-term depends on the service life of those materials. Thus, the performance assessment of structural materials under a series of environmental conditions prevailing at the environs of repositories is a matter of interest. The durability of cement paste foreseen as backfill in a deep borehole for disposal of disused sealed radioactive sources is investigated in the development of the repository concept. Results are intended to be part of the body of evidence in the safety case of the proposed disposal technology. This paper presents the results of X-Ray Diffraction (XRD) Analysis of cement paste exposed to varying temperatures and simulated groundwater after samples received the radiation dose that the cement paste will accumulate until complete decay of the radioactive sources. The XRD analysis of cement paste samples realized in this work allowed observing some differences in the results of cement paste specimens that were submitted to different treatments. The cluster analysis of results was able to group tested samples according to the applied treatments. Mineralogical differences, however, are tenuous and, apart from ettringite, are hardly observed. The absence of ettringite in all the seven specimens that were kept in dry storage at high temperature had hardly occurred by natural variations in the composition of hydrated cement paste because ettringite is observed in all tested except the seven specimens. Therefore this absence is certainly the result of the treatments and could be explained by the decomposition of ettringite. Although the temperature of decomposition is about 110-120 deg. C, it may be initially decomposed to meta-ettringite, an amorphous compound, above 50 deg. C in the absence of water. Influence of irradiation on the mineralogical composition was not observed when the treatment was analyzed individually or when analyzed under the possible synergic effect with other treatments. However, the radiation dose to which specimens were exposed is only a fraction of the accumulated dose in cement paste until complete decay of some sources. Therefore, in the short term, the conditions deemed to prevail in the repository environment may not influence the properties of cement paste at detectable levels. Under the conditions presented in this work, it is not possible to predict the long term evolution of these properties. (authors)

  8. XRD Technique: A way to disseminate structural changes in iron-based amorphous materials

    SciTech Connect

    Saw, C K; Lian, T; Day, D; Farmer, J

    2007-05-24

    Prevention of corrosion is a vital goal for the Department of Defense when billions of dollars are spent every year. Corrosion resistant materials have applications in all sort of military vehicles, and more importantly in naval vessels and submarines which come in contact with the seawater. It is known that corrosion resistance property can be improved by the used of structurally designed materials in the amorphous state where the atoms are arranged in a non-periodic fashion and specific atoms, tailored to the required properties can be interjected into the matrix for specific application. The XRD techniques reported here is to demonstrate the optimal conditions for characterization of these materials. The samples, which normally contain different compositions of Fe, Cr, B, Mo, Y, Mn, Si and W, are in the form of powders, ribbons and coatings. These results will be compared for the different forms of the sample which appears to correlate to the cooling rate during sample processing. In most cases, the materials are amorphous or amorphous with very small amount of crystallinity. In the ribbon samples for different compositions we observed that the materials are essentially amorphous. In most cases, starting from an amorphous powder sample, the coatings are also observed to be amorphous with a small amount of iron oxide on the surface, probably due to exposure to air.

  9. Structural studies with the use of XRD and Mössbauer spectroscopy of new high Manganese steels

    NASA Astrophysics Data System (ADS)

    Jablonska, Magdalena Barbara

    2014-04-01

    New high-strength austenitic and austenitic-ferritic manganese steels represent a significant potential in applications for structural components in the automotive and railway industry due to the excellent combination of high mechanical properties and good plasticity. They belong to the group of steels called AHSS (Advanced High Strength Steels) and UHSS (Ultra High Strength Steels). Application of this combination of properties allows a reduction in the weight of vehicles by the use of reduced cross-section components, and thus to reduce fuel consumption. The development and implementation of industrial production of such interesting and promising steel and its use as construction material requires an improvement of their casting properties and susceptibility to deformation in plastic working conditions. In this work, XRD, Transmission Mössbauer Spectroscopy and Conversion Electron Mössbauer Spectroscopy were employed in a study of the new high-manganese steels with a austenite and austenite-ferrite structure. The influence of the plastic deformation parameters on the changes in the structure, distribution of ferrite and disclosure of the presence of carbides was determined. The analysis of phase transformations in various times using CEMS method made possible to reveal their fine details.

  10. Material Characterization of Electrodeposited Copper-Nickel Nanolaminated Alloy by SEM, EDS, and XRD

    NASA Astrophysics Data System (ADS)

    Wang, Irene Cheryl

    Electrodeposited nanolaminated copper-nickel alloys (Cu-Ni) exhibit excellent mechanical properties due to their modulated structure and nanocrystalline microstructure. X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy were used to characterize the composition, grain size, phases, and laminate structure of a nanolaminated deposit to explore structure-process-property relationships. The processing method of interest was pulse current electrodeposition of Cu-Ni a rotating disk electrode (RDE) with increased rotation speed during deposition of Cu-rich layers. Although copper content was enhanced in this way, it also caused macroscopic swirls in the deposit's surface, which were reflected microstructurally as Cu-rich streaks, non-planar layers, and other inhomogeneous morphology in the nanolaminate coating. Bulk composition of the nanolaminate was calculated from XRD spectra as being over 67wt%Ni overall, with over 91wt% Ni in Ni-rich layers and over 43wt% Ni in Cu-rich layers. EDS data of the same deposit differed significantly from these values, suggesting an overall composition closer to 55 wt% Ni, with a Ni-rich layer composition of 81 wt% Ni and 8.4 wt% Ni in the Cu-rich layers. Grain sizes of 15.8--22.3 nm were calculated for the nanolaminated deposit compared to 13--19 nm grains in a monolithic Ni-rich deposit of Cu-Ni.

  11. XRD, TEM, IR, Raman and NMR Spectroscopy of In Situ Crystallization of Lithium Disilicate Glass

    NASA Technical Reports Server (NTRS)

    Fuss, T.; Mogus-Milankovic, A.; Ray, C. S.; Lesher, C. E.; Youngman, R.; Day, D. E.

    2006-01-01

    The structure of a Li2O-2SiO2 (LS2) glass was investigated as a function of pressure and temperature up to 6 GPa and 750 C respectively, using XRD, TEM, IR, Raman and NMR spectroscopy. Glass densified at 6 GPa has an average Si-O-Si bond angle approx.7deg lower than that found in glass processed at 4.5 GPa. At 4.5 GPa, lithium disilicate crystallizes from the glass, while at 6 GPa a new high pressure form of lithium metasilicate crystallizes. The new phase, while having lithium metasilicate crystal symmetry, contains at least 4 different Si sites. NMR results for 6 GPa sample indicate the presence of Q4 species with (Q(sup 4))Si-O-Si(Q(sup 4)) bond angles of approx.157deg. This is the first reported occurrence of Q(sup 4) species with such large bond angles in alumina free alkali silicate glass. No five- or six- coordinated Si are found.

  12. Multielemental analyses of isomorphous Indian garnet gemstones by XRD and external pixe techniques.

    PubMed

    Venkateswarulu, P; Srinivasa Rao, K; Kasipathi, C; Ramakrishna, Y

    2012-12-01

    Garnet gemstones were collected from parts of Eastern Ghats geological formations of Andhra Pradesh, India and their gemological studies were carried out. Their study of chemistry is not possible as they represent mixtures of isomorphism nature, and none of the individual specimens indicate independent chemistry. Hence, non-destructive instrumental methodology of external PIXE technique was employed to understand their chemistry and identity. A 3 MeV proton beam was employed to excite the samples. In the present study geochemical characteristics of garnet gemstones were studied by proton induced X-ray emission. Almandine variety of garnet is found to be abundant in the present study by means of their chemical contents. The crystal structure and the lattice parameters were estimated using X-Ray Diffraction studies. The trace and minor elements are estimated using PIXE technique and major compositional elements are confirmed by XRD studies. The technique is found very useful in characterizing the garnet gemstones. The present work, thus establishes usefulness and versatility of the PIXE technique with external beam for research in Geo-scientific methodology. PMID:23041780

  13. XPS, SEM and XRD investigations of CdSe films prepared by chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Vargas-Hernández, C.; Lara, V. C.; Vallejo, J. E.; Jurado, J. F.; Giraldo, O.

    2005-07-01

    Chemical bath deposition (CBD), a direct low cost technique that involves a cadmium salt solution, a complexing agent and a chalcogen source, was used to prepare CdSe semiconductor films. The most favourable conditions for acceptable quality CdSe films grown on glass were obtained. Commercially available microscope glass slides (with a size of 1 cm × 1 cm × 1 mm) were used as substrates to deposit CdSe films. CdSe films were deposited in a freshly prepared aqueous solution containing CdSO4 (0.2-0.4 M), NH4OH (3.8-14 M) as a complexing agent for slow release of Cd2+ ions, and Na2SeSO3 (0.118 and 0.16) as a source of Se2- ions. The solutions were prepared in deionized water. The glass slides were immersed in a mixture of CdSO4-NH4OH for 5 min before the solution of Na2SeSO3 was added. The bath temperature varied from 20 to 60 °C. Structural and morphological quality of the films was analyzed by XRD, SEM, EDS, and XPS. The results show that the crystallinity of the CdSe films as-deposited is improved by increasing temperature. The initial growth stages of CdSe films at 20 and 60 °C start on CdOx and Cd(OH)2 buffer layers respectively.

  14. FTIR spectroscopic, thermal and XRD characterization of hydroxyapatite from new natural sources

    NASA Astrophysics Data System (ADS)

    Shaltout, Abdallah A.; Allam, Moussa A.; Moharram, Mohamed A.

    2011-12-01

    The inorganic constituents of 5 different plants (leaves and stalks) were investigated by using Fourier transformer infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermal analysis including thermal gravimetric analysis (TGA), derivative thermogravimetry (DTG) and differential scanning calorimetry (DSC). These plants are Catha edulis (Khat), basil, mint, green tea and trifolium. The absorption bands of carbonate ions CO 32- was exhibited at 1446 cm -1, and the phosphate ions PO 43- was assigned at 1105 and 1035 cm -1. At high temperatures (600, 700 and 600 °C) further absorption bands of the phosphate ions PO 43- was assigned at the frequencies 572, 617, 962, 1043 and 1110 cm -1 and the vibrational absorption band of the carbonate ions CO 32- was assigned at 871, 1416 and 1461 cm -1. X-ray diffraction and thermal analysis confirm the obtained results of FITR. Results showed that the main inorganic constituents of C. edulis and basil leaves are hydroxyapatite whereas the hydroxyapatite content in the other plant samples is less than that in case of C. edulis and basil plant leaves.

  15. A 4-(o-chlorophenyl)-2-aminothiazole: microwave assisted synthesis, spectral, thermal, XRD and biological studies.

    PubMed

    Rajmane, S V; Ubale, V P; Lawand, A S; Nalawade, A M; Karale, N N; More, P G

    2013-11-01

    A 4-(o-chlorophenyl)-2-aminothiazole (CPAT) has been synthesized by reacting o-chloroacetophenone, iodine and thiourea under microwave irradiation as a green chemistry approach. The reactions proceed selectively and within a couple of minutes giving high yields of the products. The compound was characterized by elemental, spectral (UV-visible, IR, NMR and GC-MS), XRD and thermal analyses. The TG curve of the compound was analyzed to calculate various kinetic parameters (n, E, Z, ?S and ?G) by using Coats-Redfern (C.R.), MacCallum-Tanner (M.T.) and Horowitz-Metzger (H.M.) method. The compound was tested for the evaluation of antibacterial activity against B. subtilis and E. coli and antifungal activity against A. niger and C. albicans. The compound was evaluated for their in vitro nematicidal activity on plant parasitic nematode Meloidogyne javanica and molluscicidal activity on fresh water helminthiasis vector snail Lymnea auricularia. The compound is biologically active in very low concentration. X-ray diffraction study suggests a triclinic crystal system for the compound. PMID:23860403

  16. ?-XRF/?-RS vs. SR ?-XRD for pigment identification in illuminated manuscripts

    NASA Astrophysics Data System (ADS)

    van der Snickt, G.; de Nolf, W.; Vekemans, B.; Janssens, K.

    2008-07-01

    For the non-destructive identification of pigments and colorants in works of art, in archaeological and in forensic materials, a wide range of analytical techniques can be used. Bearing in mind that every method holds particular limitations, two complementary spectroscopic techniques, namely confocal ?-Raman spectroscopy (?-RS) and ?-X-ray fluorescence spectroscopy (?-XRF), were joined in one instrument. The combined ?-XRF and ?-RS device, called PRAXIS unites both complementary techniques in one mobile setup, which allows ?- and in situ analysis. ?-XRF allows one to collect elemental and spatially-resolved information in a non-destructive way on major and minor constituents of a variety of materials. However, the main disadvantages of ?-XRF are the penetration depth of the X-rays and the fact that only elements and not specific molecular combinations of elements can be detected. As a result ?-XRF is often not specific enough to identify the pigments within complex mixtures. Confocal Raman microscopy (?-RS) can offer a surplus as molecular information can be obtained from single pigment grains. However, in some cases the presence of a strong fluorescence background limits the applicability. In this paper, the concrete analytical possibilities of the combined PRAXIS device are evaluated by comparing the results on an illuminated sheet of parchment with the analytical information supplied by synchrotron radiation ?-X-ray diffraction (SR ?-XRD), a highly specific technique.

  17. [XRD and FTIR spectra characteristics of nacreous layer in perna viridis].

    PubMed

    Jia, Tai-Xuan; Liu, Zi-Li; Zhang, Gang-Sheng

    2009-01-01

    The XRD and FTIR of aragonites in nacreous and prismatic layer of perna viridis were systematically measured, and the frequency variations of v1, v2 and v4 band of aragonites were especially analyzed. The results showed that both of them were aragonite and the frequency of v2 band differed in them, but the frequencies of other two bands were not altered and had the same values with cavernous aragonite. In the same specie of shell, the frequency of v2 band in nacreous layers was greater than that in prismatic layers, and there was a frequency shift of v2 band between them. For the first time, the phase transformation of biogenic aragonite was detected. After nacreous aragonite was heated at 300 degrees C, the frequency shift of v2 band was found. So it is concluded that the biogenic aragonite is related to the thermal effects in crystallizing process, meanwhile it stores excess energy. All of these can provide experiential basis for studying biomineralization theory. PMID:19385222

  18. A 4-(o-chlorophenyl)-2-aminothiazole: Microwave assisted synthesis, spectral, thermal, XRD and biological studies

    NASA Astrophysics Data System (ADS)

    Rajmane, S. V.; Ubale, V. P.; Lawand, A. S.; Nalawade, A. M.; Karale, N. N.; More, P. G.

    2013-11-01

    A 4-(o-chlorophenyl)-2-aminothiazole (CPAT) has been synthesized by reacting o-chloroacetophenone, iodine and thiourea under microwave irradiation as a green chemistry approach. The reactions proceed selectively and within a couple of minutes giving high yields of the products. The compound was characterized by elemental, spectral (UV-visible, IR, NMR and GC-MS), XRD and thermal analyses. The TG curve of the compound was analyzed to calculate various kinetic parameters (n, E, Z, ?S and ?G) by using Coats-Redfern (C.R.), MacCallum-Tanner (M.T.) and Horowitz-Metzger (H.M.) method. The compound was tested for the evaluation of antibacterial activity against B. subtilis and E. coli and antifungal activity against A. niger and C. albicans. The compound was evaluated for their in vitro nematicidal activity on plant parasitic nematode Meloidogyne javanica and molluscicidal activity on fresh water helminthiasis vector snail Lymnea auricularia. The compound is biologically active in very low concentration. X-ray diffraction study suggests a triclinic crystal system for the compound.

  19. XRD, Electron Microscopy and Vibrational Spectroscopy Characterization of Simulated SB6 HLW Glasses - 13028

    SciTech Connect

    Stefanovsky, S.V.; Nikonov, B.S.; Omelianenko, B.I.; Choi, A.; Marra, J.C.

    2013-07-01

    Sample glasses have been made using SB6 high level waste (HLW) simulant (high in both Al and Fe) with 12 different frit compositions at a constant waste loading of 36 wt.%. As follows from X-ray diffraction (XRD) and optical and scanning electron microscopy (SEM) data, all the samples are composed of primarily glass and minor concentration of spinel phases which form both isometric grains and fine cubic (?1 ?m) crystals. Infrared spectroscopy (IR) spectra of all the glasses within the range of 400-1600 cm{sup -1} consist of the bands due to stretching and bending modes in silicon-oxygen, boron-oxygen, aluminum-oxygen and iron-oxygen structural groups. Raman spectra showed that for the spectra of all the glasses within the range of 850-1200 cm{sup -1} the best fit is achieved by suggestion of overlapping of three major components with maxima at 911-936 cm{sup -1}, 988-996 cm{sup -1} and 1020-1045 cm{sup -1}. The structural network is primarily composed of metasilicate chains and rings with embedded AlO{sub 4} and FeO{sub 4} tetrahedra. Major BO{sub 4} tetrahedra and BO{sub 3} triangles form complex borate units and are present as separate constituents. (authors)

  20. Structures And Magnetization Of Defect-Associated Sites In Silicon

    SciTech Connect

    Chow, L.; Gonzalez-Pons, J. C.; Barco, E. del; Vanfleet, R.; Misiuk, A.; Chai, G.

    2008-04-24

    To better understand the mechanism of the reported 'quasi-ferromagnetism' observed in Si ions self-implanted or irradiated silicon, we carry out high resolution transmission electron microscopy (HRTEM), magnetization measurements using superconducting quantum interference device (SQUID) magnetometer, and ferromagnetic resonance (FMR) measurements of the magnetic interaction of the defect-associated sites in silicon damaged by silicon self-implantation or energetic particle beams. The SQUID measurements showed that the silicon self-implanted sample has paramagnetic ordering. FMR measurements indicated the He{sup ++} irradiated sample has a ferromagnetic interaction and yields a Lande g-factor of 2.35.

  1. Swelling induced by alpha decay in monazite and zirconolite ceramics: A XRD and TEM comparative study

    NASA Astrophysics Data System (ADS)

    Deschanels, X.; Seydoux-Guillaume, A. M.; Magnin, V.; Mesbah, A.; Tribet, M.; Moloney, M. P.; Serruys, Y.; Peuget, S.

    2014-05-01

    Zirconolite and monazite matrices are potential ceramics for the containment of actinides (Np, Cm, Am, Pu) which are produced over the reprocessing of spent nuclear fuel. Actinides decay mainly through the emission of alpha particles, which in turn causes most ceramics to undergo structural and textural changes (amorphization and/or swelling). In order to study the effects of alpha decays on the above mentioned ceramics two parallel approaches were set up. The first involved the use of an external irradiation source, Au, which allowed the deposited recoil energy to be simulated. The second was based on short-lived actinide doping with 238Pu, (i.e. an internal source), via the incorporation of plutonium oxide into both the monazite and zirconolite structures during synthesis. In both types of irradiation experiments, the zirconolite samples became amorphous at room temperature with damage close to 0.3 dpa; corresponding to a critical dose of 4 × 1018 ? g-1 (i.e. ?1.3 × 1021 keV cm-3). Both zirconolite samples also showed the same degree of macroscopic swelling at saturation (?6%), with ballistic processes being the predominant damaging effect. In the case of the monazite however, the macroscopic swelling and amorphization were dependent on the nature of the irradiation. Externally, (Au), irradiated samples became amorphous while also demonstrating a saturation swelling of up to 8%. In contrast to this, the swelling of the 238Pu doped samples was much smaller at ?1%. Also, unlike the externally (Au) irradiated monazite these 238Pu doped samples remained crystalline up to 7.5 × 1018 ? g-1 (0.8 dpa). XRD, TEM and swelling measurements were used to fully characterize and interpret this behavior. The low swelling and the conservation of the crystalline state of 238Pu doped monazite samples indicates that alpha annealing took place within this material.

  2. A Novel Synthesis and Characterization Studies of Magnetic Co3O4 Nanoparticles.

    PubMed

    Valan, M F; Manikandan, A; Antony, S Arul

    2015-06-01

    Cobalt oxide (Co3O4) nanoparticles were synthesized by microwave combustion method (MCM) using urea as the fuel. For the purpose of comparison, they are also prepared by conventional combustion method (CCM). The prepared samples were examined by using X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), high resolution transmission electron microscopy (HR-TEM), UV-Visible diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy and vibrating sample magnetometer (VSM). XRD analysis indicated that the as-prepared samples have well-crystalline cubic phase. HR-TEM images showed that Co3O4 nanoparticles have sphere-like structure with an average particle size in the range of 20-25 nm (MCM) and 45-50 nm (CCM). Optical properties of Co3O4 nanoparticles revealed the presence of two band gap (1.89 and 2.54 eV (MCM), 1.68 and 2.38 eV (CCM)) values, which in turn confirmed the semi-conducting properties. VSM measurements revealed a small hysteresis loop at room temperature thus indicating a weak ferromagnetism. PMID:26369083

  3. Versatility of electrospinning in the fabrication of fibrous mat and mesh nanostructures of bismuth ferrite (BiFeO3) and their magnetic and photocatalytic activities.

    PubMed

    Bharathkumar, S; Sakar, M; K, Rohith Vinod; Balakumar, S

    2015-07-21

    This study demonstrates the fabrication of electrospun bismuth ferrite (BiFeO3/BFO) fiber mat and fibrous mesh nanostructures consisting of aligned and random fibers respectively. The formation of these one dimensional (1D) nanostructures was mediated by the drum and plate collectors in the electrospinning process that yielded aligned and random nanofibers of BFO respectively. The single phase and rhombohedral crystal structure of the fabricated 1D BFO nanostructures are confirmed through X-ray diffraction (XRD) studies. X-ray photoelectron spectroscopy (XPS) studies indicated that the fabricated fibers are stoichiometric BFO with native oxidation states +3. The surface texture and morphology are analyzed using the field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) techniques. The average size of fibers in mat and mesh nanostructures is found to be 200 nm and 150 nm respectively. The band gap energy of BFO mat and mesh deduced from their UV diffuse reflectance spectra (UV-DRS) was found to be 2.44 eV and 2.39 eV, respectively, which evidenced the improved visible light receptivity of BFO mesh compared to that of the mat. Magnetization studies using a super conducting quantum interference device (SQUID) magnetometer revealed the weak ferromagnetic properties of BFO mesh and mat nanostructures that could emerge due to the dimension induced suppression of cycloidal spin structures. The photocatalytic degradation properties of the fibrous mesh are found to be enhanced compared to that of the mat. This could be attributed to the reduced band gap energy and an improved semiconductor band-bending phenomenon in the mesh that favoured the transportation of excited charge carriers to the photocatalyst-dye interfaces and the production of more number of reactive species that lead to the effective degradation of the dye molecules. PMID:26083677

  4. Friedel's salt formation in sulfoaluminate cements: A combined XRD and {sup 27}Al MAS NMR study

    SciTech Connect

    Paul, G.; Boccaleri, E.; Buzzi, L.; Canonico, F.; Gastaldi, D.

    2015-01-15

    Four different binders based on calcium sulfoaluminate cements have been submitted to accelerated chlorination through ionic exchange on hydrated pastes, in order to investigate their ability to chemically bind chloride ions that might reduce chloride penetration. The composition of hydrated cements before and after the treatment was evaluated by means of an X-Ray Diffraction–{sup 27}Al Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy combined study, allowing to take into account even partially amorphous phases and to make quantitative assumption on the relative abundance of the different aluminium-containing phases. It was found that low SO{sub 3} Sulfoaluminate–Portland ternary systems are the most effective in binding chloride ions and the active role played by different members of the AFm family in chloride uptake was confirmed. Moreover, a peculiar behavior related to the formation of Friedel's salt in different pH conditions was also established for the different cements.

  5. A TEM and XRD Study of (BiS) 1+?(Nb 1+?S 2) n Misfit Layer Structures

    NASA Astrophysics Data System (ADS)

    Otero-Diaz, L. C.; Withers, R. L.; Gomez-Herrero, A.; Welberry, T. R.; Schmid, S.

    1995-02-01

    Monolayer and bilayer lamellar misfit layered chalcogenides within the BiS-NbS 2 system have been synthesized and studied via TEM and XRD. Both BiS and NbS 2 parent substructures are shown to have very close to orthorhombic symmetry in the former case, but definite monoclinic symmetry in the latter. Stacking disorder and its effect upon electron diffraction patterns is investigated via higher order Laue zone (HOLZ) diffraction. In addition to the usual set of reflections for such systems, an additional set of weak, somewhat diffuse satellite reflections (not previously reported before for any other misfit layered chalcogenide) have been observed. Bilayer tubular crystals have also been studied by XRD. A close relationship with the corresponding lamellar bilayer phase is established, and some unusual features of its reciprocal lattice are pointed out.

  6. Leonardo da Vinci's drapery studies: characterization of lead white pigments by µ-XRD and 2D scanning XRF

    NASA Astrophysics Data System (ADS)

    Gonzalez, Victor; Calligaro, Thomas; Pichon, Laurent; Wallez, Gilles; Mottin, Bruno

    2015-11-01

    This work focuses on the composition and microstructure of the lead white pigment employed in a set of paintworks, using a combination of µ-XRD and 2D scanning XRF, directly applied on five drapery studies attributed to Leonardo da Vinci (1452-1519) and conserved in the Département des Arts Graphiques, Musée du Louvre and in the Musée des Beaux- Arts de Rennes. Trace elements present in the composition as well as in the lead white highlights were imaged by 2D scanning XRF. Mineral phases were determined in a fully noninvasive way using a special µ-XRD diffractometer. Phase proportions were estimated by Rietveld refinement. The analytical results obtained will contribute to differentiate lead white qualities and to highlight the artist's technique.

  7. An exploratory method to detect tephras from quantitative XRD scans: Examples from Iceland and east Greenland marine sediments

    USGS Publications Warehouse

    Andrews, John T.; Eberl, D.D.; Kristjansdottir, G.B.

    2006-01-01

    Tephras, mainly from Iceland, are becoming increasingly important in interpreting leads and lags in the Holocene climate system across NW Europe. Here we demonstrate that Quantitative Phase Analysis of x-ray diffractograms of the 150 um fraction and identify these same peaks in XRD scans - two of these correlate geochemically and chronologically with Hekla 1104 and 3. At a distal site to the WNW of Iceland, on the East Greenland margin (core MD99-2317), the weight% of volcanic glass reaches values of 11% at about the time of the Saksunarvatn tephra. The XRD method identifies the presence of volcanic glass but not its elemental composition; hence it will assist in focusing attention on specific sections of sediment cores for subsequent geochemical fingerprinting of tephras. ?? 2006 SAGE Publications.

  8. Synthesis and XRD/PL Studies of Pure and Sb2O3 Doped ZnO Nanophases

    SciTech Connect

    Boulares, N.; Guergouri, K.; Tabet, N.; Monty, C.

    2007-08-22

    Pure and Sb2O3 (0 to 5% molar fraction) doped ZnO nanophases were synthesized using a sublimation-condensation method in a solar furnace. The initial and final powders were characterized by X-ray diffraction (XRD) and photoluminescence (PL) techniques. XRD results showed no significant change in the lattice parameters and the presence of a new phase Zn7O2Sb12 in the highly doped micropowders but not in the nanopowders. The photoluminescence spectra showed a strong donor-acceptor pair (DAP) emission in the pure untreated ZnO micropowder which is drastically reduced in pure and doped nanopowders. The donor-bound excitonic band (DX) includes three well resolved peaks in the PL spectra of the doped micropowders while the spectra of doped nanopowders showed a broader band. Furthermore, the free exciton emission was absent in all doped samples.

  9. Leonardo da Vinci's drapery studies: characterization of lead white pigments by µ-XRD and 2D scanning XRF

    NASA Astrophysics Data System (ADS)

    Gonzalez, Victor; Calligaro, Thomas; Pichon, Laurent; Wallez, Gilles; Mottin, Bruno

    2015-08-01

    This work focuses on the composition and microstructure of the lead white pigment employed in a set of paintworks, using a combination of µ-XRD and 2D scanning XRF, directly applied on five drapery studies attributed to Leonardo da Vinci (1452-1519) and conserved in the Département des Arts Graphiques, Musée du Louvre and in the Musée des Beaux-Arts de Rennes. Trace elements present in the composition as well as in the lead white highlights were imaged by 2D scanning XRF. Mineral phases were determined in a fully noninvasive way using a special µ-XRD diffractometer. Phase proportions were estimated by Rietveld refinement. The analytical results obtained will contribute to differentiate lead white qualities and to highlight the artist's technique.

  10. In-Situ Study of Gaseous Reduction of Magnetite Doped with Alumina Using High-Temperature XRD Analysis

    NASA Astrophysics Data System (ADS)

    Kapelyushin, Yury; Sasaki, Yasushi; Zhang, Jianqiang; Jeong, Sunkwang; Ostrovski, Oleg

    2015-12-01

    The reduction of magnetite of technical grade and magnetite doped with 3 mass pct Al2O3 was studied in situ using high-temperature XRD (HT-XRD) analysis. Magnetite was reduced by CO-CO2 gas (80 vol pct CO) at 1023 K (750 °C). Reduction of magnetite doped with alumina occurred from the Fe3O4-FeAl2O4 solid solution which has a miscibility gap with critical temperature of 1133 K (860 °C). The degree of reduction of magnetite was derived using Rietveld refinement of the HT-XRD spectra; the compositions of the Fe3O4-FeAl2O4 solid solution and the concentrations of carbon in ?-iron were determined from the lattice constants of the solutions. The reduction of magnetite progressed topochemically with the formation of a dense iron shell. The reduction of alumina-containing magnetite started along certain lattice planes with the formation of a network-like structure. Reduction of alumina-containing magnetite was faster than that of un-doped magnetite; this difference was attributed to the formation of the network-like structure. Hercynite content in the Fe3O4-FeAl2O4 solid solution in the process of reduction of magnetite doped with 3 mass pct Al2O3 increased from 5.11 to 20 mass pct, which is close to the miscibility gap at 1023 K (750 °C). The concentration of carbon in ?-Fe (0.76 mass pct) formed in the reduced sample of magnetite doped with 3 mass pct Al2O3 was close to the equilibrium value with 80 vol pct CO to 20 vol pct CO2 gas used in the HT-XRD experiments.

  11. Characterizing the Phyllosilicates and Amorphous Phases Found by MSL Using Laboratory XRD and EGA Measurements of Natural and Synthetic Materials

    NASA Technical Reports Server (NTRS)

    Rampe, Elizabeth B.; Morris, Richard V.; Chipera, Steve; Bish, David L.; Bristow, Thomas; Archer, Paul Douglas; Blake, David; Achilles, Cherie; Ming, Douglas W.; Vaniman, David; Crisp, Joy A.; DesMarais, David J.; Downs, Robert; Farmer, Jack D.; Morookian, John Michael; Morrison, Shaunna; Sarrazin, Philippe; Spanovich, Nicole; Treiman, Allan H.; Yen, Albert S.

    2013-01-01

    The Curiosity Rover landed on the Peace Vallis alluvial fan in Gale crater on August 5, 2012. A primary mission science objective is to search for past habitable environments, and, in particular, to assess the role of past water. Identifying the minerals and mineraloids that result from aqueous alteration at Gale crater is essential for understanding past aqueous processes at the MSL landing site and hence for interpreting the site's potential habitability. X-ray diffraction (XRD) data from the CheMin instrument and evolved gas analyses (EGA) from the SAM instrument have helped the MSL science team identify phases that resulted from aqueous processes: phyllosilicates and amorphous phases were measure in two drill samples (John Klein and Cumberland) obtained from the Sheepbed Member, Yellowknife Bay Fm., which is believed to represent a fluvial-lacustrine environment. A third set of analyses was obtained from scoop samples from the Rocknest sand shadow. Chemical data from the APXS instrument have helped constrain the chemical compositions of these secondary phases and suggest that the phyllosilicate component is Mg-enriched and the amorphous component is Fe-enriched, relatively Si-poor, and S- and H-bearing. To refine the phyllosilicate and amorphous components in the samples measured by MSL, we measured XRD and EGA data for a variety of relevant natural terrestrial phyllosilicates and synthetic mineraloids in laboratory testbeds of the CheMin and SAM instruments. Specifically, Mg-saturated smectites and vermiculites were measured with XRD at low relative humidity to understand the behavior of the 001 reflections under Mars-like conditions. Our laboratory XRD measurements suggest that interlayer cation composition affects the hydration state of swelling clays at low RH and, thus, the 001 peak positions. XRD patterns of synthetic amorphous materials, including allophane, ferrihydrite, and hisingerite were used in full-pattern fitting (FULLPAT) models to help determine the types and abundances of amorphous phases in the martian rocks and sand shadow. These models suggest that the rocks and sand shadow are composed of approx 30% amorphous phases. Sulfate-adsorbed allophane and ferrihydrite were measured by EGA to further understand the speciation of the sulfur present in the amorphous component. These data indicate that sulfate adsorbed onto the surfaces of amorphous phases could explain a portion of the SO2 evolution in the Rocknest SAM data. The additional constraints placed on the mineralogy and chemistry of the aqueous alteration phases through our laboratory measurements can help us better understand the nature of the fluids that affected the different samples and devise a history of aqueous alteration for the Sheepbed Member of the Yellowknife Bay Fm. at Gale crater.

  12. Transmission X-ray Diffraction (XRD) Patterns Relevant to the MSL Chemin Amorphous Component: Sulfates And Silicates

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; Rampe, E. B.; Graff, T. G.; Archer, P. D., Jr.; Le, L.; Ming, D. W.; Sutter, B.

    2015-01-01

    The Mars Science Laboratory (MSL) CheMin instrument on the Curiosity rover is a transmission X-ray diffractometer (Co-Kalpha radiation source and a approx.5deg to approx.52deg 2theta range) where the analyzed powder samples are constrained to have discrete particle diameters <150 microns by a sieve. To date, diffraction patterns have been obtained for one basaltic soil (Rocknest (RN)) and four drill fines of coherent rock (John Klein (JK), Cumberland (CB), Windjana (WJ), and Confidence Hills (CH)). The CheMin instrument has detected and quantified the abundance of both primary igneous (e.g., feldspar, olivine, and pyroxene) and secondary (e.g., Ca-sulfates, hematite, akaganeite, and Fe-saponite) minerals. The diffraction patterns of all CheMin samples are also characterized by a broad diffraction band centered near 30deg 2theta and by increasing diffraction intensity (scattering continuum) from approx.15deg to approx.5deg, the 2theta minimum. Both the broad band and the scattering continuum are attributed to the presence of an XRD amorphous component. Estimates of amorphous component abundance, based on the XRD data itself and on mass-balance calculations using APXS data crystalline component chemistry derived from XRD data, martian meteorites, and/or stoichiometry [e.g., 6-9], range from approx.20 wt.% to approx.50 wt.% of bulk sample. The APXSbased calculations show that the amorphous component is rich in volatile elements (esp. SO3) and is not simply primary basaltic glass, which was used as a surrogate to model the broad band in the RN CheMin pattern. For RN, the entire volatile inventory (except minor anhydrite) is assigned to the amorphous component because no volatile-bearing crystalline phases were reported within detection limits [2]. For JK and CB, Fesaponite, basanite, and akaganeite are volatile-bearing crystalline components. Here we report transmission XRD patterns for sulfate and silicate phases relevant to interpretation of MSL-CheMin XRD amorphous components.

  13. Low temperature structural anomalies arising from competing exchange interactions in pyrochlore Nd2Ru2O7 probed by XRD and EXAFS.

    PubMed

    Chen, Shi-Wei; Fu, Shao-Wei; Pao, Chih-Wen; Lee, Jenn-Min; Chen, Shin-An; Haw, Shu-Chih; Lee, Jyh-Fu; Liu, Chun-Hsia; Chang, Chung-Kai; Chuang, Yu-Chun; Sheu, Hwo-Shuenn; Lu, Kueih-Tzu; Ku, Szu-Tu; Chang, Lieh-Jeng; Chen, Jin-Ming

    2015-09-28

    Quantitative structural parameters of pyrochlore Nd2Ru2O7, with temperature dependence, have been derived upon fitting XRD and EXAFS data. An anomalous expansion of the lattice parameter and the Ru-O bond length indicates a structural instability at low temperatures; in particular, an increase in the non-thermal term of the mean square fluctuation in the bond length is the evidence for a static disorder of Ru atoms. This static disorder is closely correlated with a decrease in the average Ru-O-Ru bond angle with decreasing temperature, favoring the short-range ferromagnetic coupling in the material. This ferromagnetic coupling formed thus triggered the spin frustration at low temperature when the contradictory constraints of antiferromagnetic interaction act upon the same Ru site in the corner-sharing tetrahedrons of pyrochlore Nd2Ru2O7. This study demonstrates that the spin frustration arising from the competition of ferromagnetic/antiferromagnetic interactions in pyrochlore Nd2Ru2O7 will cause structural instability especially on the atomic scale, which provides a new point of view to help understand its particular magnetic state. PMID:26299873

  14. Intrinsic magnetic properties of bimetallic nanoparticles elaborated by cluster beam deposition.

    PubMed

    Dupuis, V; Khadra, G; Hillion, A; Tamion, A; Tuaillon-Combes, J; Bardotti, L; Tournus, F

    2015-11-14

    In this paper, we present some specific chemical and magnetic order obtained very recently on characteristic bimetallic nanoalloys prepared by mass-selected Low Energy Cluster Beam Deposition (LECBD). We study how the competition between d-atom hybridization, complex structure, morphology and chemical affinity affects their intrinsic magnetic properties at the nanoscale. The structural and magnetic properties of these nanoalloys were investigated using various experimental techniques that include High Resolution Transmission Electron Microscopy (HRTEM), Superconducting Quantum Interference Device (SQUID) magnetometry, as well as synchrotron techniques such as Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Magnetic Circular Dichroism (XMCD). Depending on the chemical nature of the nanoalloys we observe different magnetic responses compared to their bulk counterparts. In particular, we show how specific relaxation in nanoalloys impacts their magnetic anisotropy; and how finite size effects (size reduction) inversely enhance their magnetic moment. PMID:26206215

  15. Comparative investigation of Fourier Transform Infrared (FT-IR) spectroscopy and X-ray Diffraction (XRD) in the determination of cotton fiber crystallinity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Despite considerable efforts in developing the curve-fitting protocol to evaluate the crystallinity index (CI) from the X-ray diffraction (XRD) measurement, in its present state XRD procedure can only provide a qualitative or semi-quantitative assessment of the amounts of crystalline or amorphous po...

  16. Doxorubicin loaded PEG-b-poly(4-vinylbenzylphosphonate) coated magnetic iron oxide nanoparticles for targeted drug delivery

    NASA Astrophysics Data System (ADS)

    Ha?upka-Bryl, Magdalena; Bednarowicz, Magdalena; Dobosz, Bernadeta; Krzyminiewski, Ryszard; Zalewski, Tomasz; Wereszczy?ska, Beata; Nowaczyk, Grzegorz; Jarek, Marcin; Nagasaki, Yukio

    2015-06-01

    Due to their unique physical properties, superparamagnetic iron oxide nanoparticles are increasingly used in medical applications. They are very useful carriers for delivering antitumor drugs in targeted cancer treatment. Magnetic nanoparticles with chemiotherapeutic were synthesized by coprecipitation method followed by coating with biocompatible polymer. The aim of this work is to characterize physical and magnetic properties of synthesized nanoparicles. Characterization was carried out using EPR, HRTEM, X-ray diffraction, SQUID and NMR methods. The present findings show that synthesized nanosystem is promising tool for potential magnetic drug delivery.

  17. Lead Speciation in House Dust from Canadian Urban Homes Using EXAFS Micro-XRF and Micro-XRD

    SciTech Connect

    L MacLean; S Beauchemin; P Rasmussen

    2011-12-31

    X-ray absorption fine-structure (XAFS) spectroscopy, micro-X-ray fluorescence ({mu}XRF), and micro-X-ray diffraction ({mu}XRD) were used to determine the speciation of Pb in house dust samples from four Canadian urban homes having elevated Pb concentrations (>1000 mg Pb kg{sup -1}). Linear combination fitting of the XAFS data, supported by {mu}XRF and {mu}XRD, shows that Pb is complexed in a variety of molecular environments, associated with both the inorganic and organic fractions of the dust samples. The inorganic species of lead identified were as follows: Pb metal, Pb carbonate, Pb hydroxyl carbonate, Pb oxide, and Pb adsorbed to iron oxyhydroxides. Pb carbonate and/or Pb hydroxyl carbonate occurred in all four dust samples and accounted for 28 to 75% of total Pb. Pb citrate and Pb bound to humate were the organic species identified. The results of this study demonstrate the ability of XAFS to identify Pb speciation in house dust and show the potential to identify Pb sources from new homes versus older homes. Understanding Pb speciation and how it influences bioaccessibility is important for human health risk assessment and risk management decisions which aim to improve indoor environmental health.

  18. Microstructural Characterization of Water-Rich Boehmite (AlO(OH)): TEM Correlation of Apparently Divergent XRD and TGA Results

    SciTech Connect

    Allard, L.F.; Anovitz, L.M.; Benezeth, P.; Coffey, D.W.; Palmer, D.A.; Porter, W.D.; Wesolowski, D.J.

    1999-08-01

    An understanding of the solid-phase thermodynamics and aqueous speciation of aluminum is critical to our ability to understand and predict processes in a wide variety of geologic and industrial settings. Boehmite (AIO(OH)) is an important phase in the system Al2O3-H2O that has been the subject of a number of structural and thermodynamic studies since its initial synthesis [l] and discovery in nature [2]. Unfortunately, it has long been recognized that thermogravimetric analysis (TGA) of both synthetic and natural boehmite samples (that appear well crystallized by powder XRD methods) yields significant excess water - typically losing 16-16.5 wt. % on heating as compared with a nominal expected weight loss of 15.0 wt. % [3,4]. The boehmite used in our experiments was synthesized hydrothermally from acid-washed gibbsite (Al(OH)3) at 200°C. Powder XRD and SEM examination showed no evidence of the presence a contaminant phase. The TGA patterns do not suggest that this is due to adsorbed water, so a structural source is likely. We therefore undertook to examine this material by TEM to clarify this phenomenon.

  19. Copper Coordination in Cu-SSZ-13 and Cu-SSZ-16 Investigated by Variable-Temperature XRD

    SciTech Connect

    Fickel, D.; Lobo, R

    2010-01-01

    Nitrogen oxides (NO{sub x}) are a major atmospheric pollutant produced through the combustion of fossil fuels in internal combustion engines. Copper-exchanged zeolites are promising as selective catalytic reduction catalysts for the direct conversion of NO into N{sub 2} and O{sub 2}, and recent reports have shown the enhanced performance of Cu-CHA catalysts over other zeolite frameworks in the NO decomposition of exhaust gas streams. In the present study, Rietveld refinement of variable-temperature XRD synchrotron data obtained for Cu-SSZ-13 and Cu-SSZ-16 is used to investigate the location of copper cations in the zeolite pores and the effect of temperature on these sites and on framework stability. The XRD patterns show that the thermal stability of SSZ-13 is increased significantly when copper is exchanged into the framework compared with the acid form of the zeolite, H-SSZ-13. Cu-SSZ-13 is also more thermally stable than Cu-SSZ-16. From the refined diffraction patterns, the atomic positions of atoms, copper locations and occupancies, and thermal displacement parameters were determined as a function of temperature for both zeolites. Copper is found in the cages coordinated to three oxygen atoms of the six-membered rings.

  20. A comparative EBSD and micro-XRD study of the intergranular grain structure in CP-Ti

    NASA Astrophysics Data System (ADS)

    Lynch, P. A.; Tomus, D.; Bettles, C. J.; Gibson, M. A.; Stevenson, A. W.

    2010-07-01

    Electron Backscatter Diffraction (EBSD) and scanning polychromatic X-ray micro-diffraction (micro-XRD) have been applied to study the intergranular grain structure in CP-Ti strip. Prior to synchrotron experimentation, a polycrystalline CP-Ti sample was electrochemically polished and a series of fiducial markers were placed on the surface to define a 500 ?m×500 ?m region of interest. Within this area EBSD was used to obtain an orientation map of the grains at the sample surface. Synchrotron polychromatic X-ray micro-diffraction data, collected on beamline 12.3.2 at the Advanced Light Source, was then used to map an area of 200×60 ?m 2 within the region of interest. Comparison of the respective grain maps indicated an average grain size of ˜50 ?m. Micro-XRD data was initially used to locate the same surface grains determined by EBSD. Based on comparison of the Euler angles, grain orientation maps from the two data sets were found to be in close agreement. The typical rolling texture found in CP-Ti was identified with the basal pole maxima tilted slightly toward the transverse direction. Subsequent 3D analysis of the Laue pattern intensity distribution of the surface grains revealed that some of the large grains identified by EBSD formed sub-cell structures below the sample surface.

  1. Synthesis of metal complexes involving Schiff base ligand with methylenedioxy moiety: Spectral, thermal, XRD and antimicrobial studies

    NASA Astrophysics Data System (ADS)

    Sundararajan, M. L.; Jeyakumar, T.; Anandakumaran, J.; Karpanai Selvan, B.

    2014-10-01

    Metal complexes of Zn(II), Cd(II), Ni(II), Cu(II), Fe(III), Co(II), Mn(II) Hg(II), and Ag(I) have been synthesized from Schiff base ligand, prepared by the condensation of 3,4-(methylenedioxy)aniline and 5-bromo salicylaldehyde. All the compounds have been characterized by using elemental analysis, molar conductance, FT-IR, UV-Vis, 1H NMR, 13C NMR, mass spectra, powder XRD and thermal analysis (TG/DTA) technique. The elemental analysis suggests the stoichiometry to be 1:1 (metal:ligand). The FT-IR, 1H NMR, 13C NMR and UV-Vis spectral data suggest that the ligand coordinate to the metal atom by imino nitrogen and phenolic oxygen as bidentate manner. Mass spectral data further support the molecular mass of the compounds and their structure. Powder XRD indicates the crystalline state and morphology of the ligand and its metal complexes. The thermal behaviors of the complexes prove the presence of lattice as well as coordinated water molecules in the complexes. Melting point supports the thermal stability of all the compounds. The in vitro antimicrobial effects of the synthesized compounds were tested against five bacterial and three fungal species by well diffusion method. Antioxidant activities have also been performed for all the compounds. Metal complexes show more biological activity than the Schiff base.

  2. Investigating ?-particle radiation damage in phyllosilicates using synchrotron microfocus-XRD/XAS: implications for geological disposal of nuclear waste

    NASA Astrophysics Data System (ADS)

    Bower, W. R.; Pearce, C. I.; Pimblott, S. M.; Haigh, S. J.; Mosselmans, J. F. W.; Pattrick, R. A. D.

    2014-12-01

    The response of mineral phases to the radiation fields that will be experienced in a geological disposal facility (GDF) for nuclear waste is poorly understood. Phyllosilicates are critical phases in a GDF with bentonite clay as the backfill of choice surrounding high level wastes in the engineered barrier, and clays and micas forming the most important reactive component of potential host rocks. It is essential that we understand changes in mineral properties and behaviour as a result of damage from both ? and ? radiation over long timescales. Radiation damage has been demonstrated to affect the physical integrity and oxidation state1 of minerals which will also influence their ability to react with radionuclides. Using the University of Manchester's newly commissioned particle accelerator at the Dalton Cumbrian Facility, UK, model phyllosilicate minerals (e.g. biotite, chlorite) were irradiated with high energy (5MeV) alpha particles at controlled dose rates. This has been compared alongside radiation damage found in naturally formed 'radiohalos' - spherical areas of discolouration in minerals surrounding radioactive inclusions, resulting from alpha particle penetration, providing a natural analogue to study lattice damage under long term bombardment1,2. Both natural and artificially irradiated samples have been analysed using microfocus X-ray absorption spectroscopy and high resolution X-ray diffraction mapping on Beamline I18 at Diamond Light Source; samples were probed for redox changes and long/short range disorder. This was combined with lattice scale imaging of damage using HR-TEM (TitanTM Transmission Electron Microscope). The results show aberrations in lattice parameters as a result of irradiation, with multiple damage-induced 'domains' surrounded by amorphous regions. In the naturally damaged samples, neo-formed phyllosilicate phases are shown to be breakdown products of highly damaged regions. A clear reduction of the Fe(III) component has been demonstrated in iron-bearing phyllosilicates in both naturally and artificially damaged samples. Alterations in mineral structure and chemistry will have implications for the phases' efficiency as a barrier material. 1. Pattrick, R A D et al., (2013) Min. Mag., 77, 2867-2882. 2. Bower et al., unpubl.

  3. Landed XRD/XRF analysis of prime targets in the search for past or present Martian life.

    PubMed

    Vaniman, D; Bish, D; Blake, D; Elliott, S T; Sarrazin, P; Collins, S A; Chipera, S

    1998-12-25

    Mars landers seeking evidence for past or present life will be guided by information from orbital mapping and from previous surface exploration. Several target options have been proposed, including sites that may harbor extant life and sites most likely to preserve evidence of past life These sites have specific mineralogic characteristics. Extant life might be gathered around the sinters and associated mineral deposits of rare active fumaroles, or held within brine pockets and inclusions in a few evaporite-mineral deposits. Possibilities for fossilization include deltaic and lake-bottom sediments of once-flooded craters, sinters formed by ancient hot-spring deposits, and the carbonate deposits associated with some evaporite systems. However, the highly varied mineralogy of fossil occurrences on Earth leads to the inference that Mars, an equally complex planet, could host a broad variety of potential fossilizing deposits. The abundance of volcanic systems on Mars and evidence for close associations between volcanism and water release suggest possibilities of organism entrapment and mineralization in volcaniclastic deposits, as found in some instances on Earth. Thus the targets being considered for exploration include a wide variety of unique deposits that would be characterized by silica or various nonsilicate minerals. Beyond these "special" deposits and in the most general case, an ability to distinguish mineralized from uncemented volcanic detritus may be the key to success in finding possible fossil-bearing authigenic mineralogies. A prototype miniaturized X ray diffraction/X ray fluorescence (XRD/XRF) instrument has been evaluated with silica, carbonate, and sulfate minerals and with a basalt, to examine the capabilities of this tool in mineralogic and petrologic exploration for exobiological goals. This instrument. CHEMIN (chemical and mineralogical analyzer), is based on an innovative low-power X ray tube, transmission geometry, and CCD collection and discrimination of diffracted and fluoresced X rays. The ability to accumulate and integrate the entire circumference of each complete Debye diffraction ring compensates for poor powder preparations, as might be produced by robotic sampling systems. With CHEMIN, a wide range of minerals can be uniquely identified. Using Rietveld analysis of the XRD results, mineral quantification is also possible. Expanded capabilities in phase analysis and constrained data solutions using quantitative XRD and XRF are within reach. PMID:11542260

  4. Request for X-ray Powder Diffraction Experiment (XRD) Lab. Book # ________ Peter Y. Zavalij X-ray Crystallographi Center 091 Chemistry Bldg. / College Park, MD 20742

    E-print Network

    Thirumalai, Devarajan

    Request for X-ray Powder Diffraction Experiment (XRD) Lab. Book # ________ Peter Y. Zavalij X-ray-Match C2 Discover 2max [90°] #2 Unit Cell Refinement * X'Pert MRD 2step[0.015°] #3 Rietveld Refinement

  5. Structural analysis of zeolite beta through periodic ab initio simulations of XRD and 29Si and 17O NMR spectra

    NASA Astrophysics Data System (ADS)

    Costa, Deyse G.; Capaz, Rodrigo B.

    2015-10-01

    For large systems containing hundreds of atoms in the unit cell, as usually is observed in the zeolitic materials, the use of periodic ab initio calculations is limited by the requirement of huge computation resources. In this work, by using the primitive unit cell of the zeolite beta crystal, which is 50% smaller than its conventional crystallographic unit cell, we are able to perform periodic ab initio calculations for this system. Contrary to cluster-type calculations, the correct chemical environment of the entire zeolite beta crystal is taken into account, allowing for an accurate determination of this XRD pattern and the NMR spectra of the 29Si and 17O nuclei. In particular, we present a complete characterization of the distribution of quadrupole coupling constants (Cq), asymmetry parameter (?), and isotropic chemical shifts for the ?isoSi and the ?isoO, which have not yet been investigated experimentally.

  6. Real-Time XRD Studies of Li-O2 Electrochemical Reaction in Nonaqueous Lithium-Oxygen Battery.

    PubMed

    Lim, Hyunseob; Yilmaz, Eda; Byon, Hye Ryung

    2012-11-01

    Understanding of electrochemical process in rechargeable Li-O2 battery has suffered from lack of proper analytical tool, especially related to the identification of chemical species and number of electrons involved in the discharge/recharge process. Here we present a simple and straightforward analytical method for simultaneously attaining chemical and quantified information of Li2O2 (discharge product) and byproducts using in situ XRD measurement. By real-time monitoring of solid-state Li2O2 peak area, the accurate efficiency of Li2O2 formation and the number of electrons can be evaluated during full discharge. Furthermore, by observation of sequential area change of Li2O2 peak during recharge, we found nonlinearity of Li2O2 decomposition rate for the first time in ether-based electrolyte. PMID:26296031

  7. Spectral Resolution for Five-Element, Filtered, X-Ray Detector (XRD) Arrays Using the Methods of Backus and Gilbert

    SciTech Connect

    FEHL,DAVID LEE; BIGGS,F.; CHANDLER,GORDON A.; STYGAR,WILLIAM A.

    2000-01-17

    The generalized method of Backus and Gilbert (BG) is described and applied to the inverse problem of obtaining spectra from a 5-channel, filtered array of x-ray detectors (XRD's). This diagnostic is routinely fielded on the Z facility at Sandia National Laboratories to study soft x-ray photons ({le}2300 eV), emitted by high density Z-pinch plasmas. The BG method defines spectral resolution limits on the system of response functions that are in good agreement with the unfold method currently in use. The resolution so defined is independent of the source spectrum. For noise-free, simulated data the BG approximating function is also in reasonable agreement with the source spectrum (150 eV black-body) and the unfold. This function may be used as an initial trial function for iterative methods or a regularization model.

  8. Preparation of biocompatible magnetite-carboxymethyl cellulose nanocomposite: characterization of nanocomposite by FTIR, XRD, FESEM and TEM.

    PubMed

    Habibi, Neda

    2014-10-15

    The preparation and characterization of magnetite-carboxymethyl cellulose nano-composite (M-CMC) material is described. Magnetite nano-particles were synthesized by a modified co-precipitation method using ferrous chloride tetrahydrate and ferric chloride hexahydrate in ammonium hydroxide solution. The M-CMC nano-composite particles were synthesized by embedding the magnetite nanoparticles inside carboxymethyl cellulose (CMC) using a freshly prepared mixture of Fe3O4 with CMC precursor. Morphology, particle size, and structural properties of magnetite-carboxymethyl cellulose nano-composite was accomplished using X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR) and field emission scanning electron microscopy (FESEM) analysis. As a result, magnetite nano-particles with an average size of 35nm were obtained. The biocompatible Fe3O4-carboxymethyl cellulose nano-composite particles obtained from the natural CMC polymers have a potential range of application in biomedical field. PMID:24820322

  9. Reciprocal space XRD mapping with varied incident angle as a probe of structure variation within surface depth

    SciTech Connect

    Yang, Qiguang; Williams, Frances; Zhao, Xin; Reece, Charles E.; Krishnan, Mahadevan

    2013-09-01

    In this study, we used a differential-depth X-Ray diffraction Reciprocal Spacing Mapping (XRD RSM) technique to investigate the crystal quality of a variety of SRF-relevant Nb film and bulk materials. By choosing different X-ray probing depths, the RSM study successfully revealed evolution the of materials? microstructure after different materials processes, such as energetic condensation or surface polishing. The RSM data clearly measured the materials? crystal quality at different thickness. Through a novel differential-depth RSM technique, this study found: I. for a heteroepitaxy Nb film Nb(100)/MgO(100), the film thickening process, via a cathodic arc-discharge Nb ion deposition, created a near-perfect single crystal Nb on the surface?s top-layer; II. for a mechanically polished single-crystal bulk Nb material, the microstructure on the top surface layer is more disordered than that in-grain.

  10. Radiometric, SEM and XRD investigation of black sands at Chituc placer deposit North of the City of Navodari, Romania

    NASA Astrophysics Data System (ADS)

    Duliu, Octavian G.; Blebea-Apostu, Ana-Maria; Gomoiu, Claudia; Margineanu, Romul M.; Costea, Constantin; Dumitras, Delia; Ion, Adriana

    2014-05-01

    The black sand of the Chituc marine sandbank situated northern of the city of Navodari (Romania), displayed anomalous high ambient dose rates. Field measurements performed during 2013 Summer campaign recorded in some places dose rate up to 200 nSv/h, significantly overpassing the average value of 44 ± 20 nSv/h recorded along the entire Southern sector of Romanian Black Sea shore. Here, the sand presented a black-brownish hue, different by the usual white yellowish colour. Gamma ray spectrometry performed on both Slanic-Prahove Underground Low Background Laboratory and Gological Institute Radiometric Facilities showed with clarity the dominance of 228-Ac radioisotope in the 50 microns fraction together with the 226-Ra and traces of 40-K. No significant amount of anthropogenic 137-Cs were identified. The other granulometric fractions, i.e. 315, 200 as well 100 microns presented a significant lower level of radioactivity. X-ray diffraction (XRD) as well as Scanning Electron Microsopy (SEM) data attested the presence of monazite, zircon, magnetite, ilmenite, andradite, quartz, aragonite and albite in different proportions, the monazite and zircon being preponderant in the 50 microns, the most radioactive fraction. Based on both radiometric and XRD determinations we come to the conclusion that the evidenced radioactivity could be attributed to both uranium and thorium series in the zircon and monazite fractions and to a lesser extent in the garnet fraction. By its position with respect to Danube Delta, the Chituc marine sandbank could be regarded as a placer where heavy minerals discharged in the Black Sea by the Danube River and transported southward by the Great Black Sea Rim are deposited by gravity separation during sedimentary processes. The implications of the Chituc levee radioactive anomaly for any further human activity are analysed and discussed. Acknowledgement: Work done within the BS ERA NET 041 project in the frame of BS-ERA.NET Pilot Joint CAll 2010-2011.

  11. Mineralogical Capabilities of the CheMin XRD/XRF instrument on Mars Science Laboratory (MSL ’11)

    NASA Astrophysics Data System (ADS)

    Blake, D. F.; Vaniman, D. T.; Yen, A. S.; Chen, C.; Sarrazin, P.; Bish, D. L.; Chipera, S.; Morris, R. V.

    2009-12-01

    A principal goal of the Mars Science Laboratory (MSL ‘11) mission is to identify and characterize present or past habitable environments on Mars. By determining the mineralogical composition of rocks or soil, one can often deduce the conditions under which they formed, or their subsequent diagenetic or metamorphic history. The CheMin mineralogical instrument [1-3] will return quantitative X-ray diffraction data (XRD) and qualitative X-ray fluorescence data (XRF; 14 < Z < 92) from scooped soils and drilled rock powders collected from the Mars surface. Small amounts (45-65 mm3) of sample material sieved to <150 µm will be delivered through a funnel to one of 27 reuseable sample cells located on a sample wheel. Sample cells are 8-mm diameter discs bounded by 7-µm thick Mylar or Kapton windows spaced 170 µm apart. Within this volume, the sample is shaken by piezoelectric vibration at sonic frequencies, causing the powder to flow past a narrow, collimated X-ray beam in random orientations during the course of an analysis. CheMin is designed to have a Minimum Detection Limit (MDL) of <3% by mass, accuracy better than 15% and precision better than 10% for phases present in concentrations >4X MDL (12%). CheMin uses a Co X-ray tube so that absorption in iron-rich samples is minimized. The resolution of the diffraction patterns is <0.35° 2?, and the angular measurement range is 4-55° 2?. The capabilities of the FM instrument were tested during ThermoVac using mineral and ceramic standards contained on the FM sample wheel. Standards include 88:12 and 97:3 mixtures of beryl:quartz for assessment of the accuracy and precision of quantitative analyses, miminum detection limits, 2? range and 2? resolution; a compositionally diverse ceramic material for XRF evaluation; arcanite (K2SO4); and an amphibole. Analyses were performed under Mars atmospheric pressure at a range of Rover Avionics Mounting Platform (RAMP) temperatures from -40C to +26C. Within the predicted Mars RAMP operating temperatures of 0C to +20C, peak-to-background ratios in the XRD pattern and FWHM of elemental peaks in XRF spectra were within proscribed limits. The beryl:quartz mixtures show some anomalous phase segregation during sample shaking that is being investigated. Mineral detection and energy resolution capabilites meet or exceed requirements. References: [1] http://msl-scicorner.jpl.nasa.gov/Instruments/CheMin/. [2] LPSC40 #1484 (2009). [3] Martian Phyllosilicates: Recorders of Aqueous Processes #7006 (2008).

  12. Metal and Alloy Nanowires: Iron and Invar Inside Carbon Nanotubes

    E-print Network

    Dunin-Borkowski, Rafal E.

    -dienyliron, Aldrich 98%) powders under reduced pressures (e.g. 100 torr) with an Ar flow rate of ca. 20 seem at 1050°C. With the introduction ofInvar in carbon nanotubes it is now possible to study the physico chemical properties, HRTEM, EELS, XRD and SQUID. The magnetic properties of metal- and alloy-filled nanotubes may be applied

  13. Magnetite and magnetite/silver core/shell nanoparticles with diluted magnet-like behavior

    SciTech Connect

    Garza-Navarro, Marco; Gonzalez, Virgilio; Ortiz, Ubaldo; De la Rosa, Elder

    2010-01-15

    In the present work is reported the use of the biopolymer chitosan as template for the preparation of magnetite and magnetite/silver core/shell nanoparticles systems, following a two step procedure of magnetite nanoparticles in situ precipitation and subsequent silver ions reduction. The crystalline and morphological characteristics of both magnetite and magnetite/silver core/shell nanoparticles systems were analyzed by high resolution transmission electron microscopy (HRTEM) and nanobeam diffraction patterns (NBD). The results of these studies corroborate the core/shell morphology and the crystalline structure of the magnetite core and the silver shell. Moreover, magnetization temperature dependent, M(T), measurements show an unusual diluted magnetic behavior attributed to the dilution of the magnetic ordering in the magnetite and magnetite/silver core/shell nanoparticles systems. - Graphical abstract: Biopolymer chitosan was used as stabilization media to synthesize both magnetite and magnetite/silver core/shell nanoparticles. Results of HRTEM and NBD patterns confirm core/shell morphology of the obtained nanoparticles. It was found that the composites show diluted magnet-like behavior.

  14. Simplified Procedure for Estimating Epitaxy of La2Zr2O7-Buffered NiW RABITS Using XRD

    SciTech Connect

    Rikel, Mark O.; Isfort, Dirk; Klein, Marcel; Ehrenberg, Jurgen; Bock, Joachim; Specht, Eliot D; Sun-Wagener, Ming; Weber, Oxana; Sporn, Dieter; Engel, Sebastian; de Haas, Oliver; Semerad, Robert; Schubert, Margitta; Holzapfel, Bernhard

    2009-01-01

    Abstract A procedure is developed for assessing the epitaxy of La(2-x)Zr(2+x)O(7) (LZO) layers on NiW RABITS. Comparing XRD patterns (theta / 2-theta scans and 2D rocking curves) of LZO films of known thickness (ellipsometry or reflectometry measurements) with those of standard samples (100% epitaxial LZO film and an isotropic LZO pellet of known density), we estimate the epitaxial (EF), and polycrystalline (PF) fractions of LZO within the layer. The procedure was tested using MOD-LZO(100 nm)/NiW tape samples with varied from 3 to 90% (reproducibly prepared by varying the humidity of Ar-5%H2 gas during heat treatment). A qualitative agreement with RHEED and quantitative (within 10%) agreement with the EBSD results was shown. Correlation between EF and Jc in 600 nm thick YBCO layer deposited on MOD-LZO/NiW using thermal coevaporation enables us to impose the EF=80% margin on the quality of LZO layer for the particular conductor architecture.

  15. Composite uranium carbide targets at TRIUMF: Development and characterization with SEM, XRD, XRF and L-edge densitometry

    NASA Astrophysics Data System (ADS)

    Kunz, Peter; Bricault, Pierre; Dombsky, Marik; Erdmann, Nicole; Hanemaayer, Vicky; Wong, John; Lützenkirchen, Klaus

    2013-09-01

    The production of radioactive ion beams (RIB) from spallation targets by irradiation with a continuous 500 MeV proton beam, has been routine at TRIUMF for several years. Based on the experience with composite refractory carbide targets a procedure for the fabrication of UC2/C targets was developed. It includes the preparation of UC2 by carbothermal reduction of UO2, the slip-casting of fine-grained UC2/C slurry on graphite foil under inert gas atmosphere and the cutting of composite target discs which are stacked up to a lamellar structure. The thermal properties of such an arrangement are adequate to withstand the high power deposition of an intense, continuous proton beam and also beneficial for the fast release of short-lived radioactive isotopes. Molecular structure, particle size and the impact of sintering of the target discs were investigated via XRD and SEM. Thickness and mass distribution were measured with position-sensitive LIII-edge densitometry. The results confirm that the properties of the UC2/C target material are well suited for RIB production at TRIUMF while there is still room for improvement with regard to uniformity of mass distribution in target disc thickness.

  16. NGR, XRD and TEM/SAED investigations on waste dumps materials with a view to recover precious metals

    NASA Astrophysics Data System (ADS)

    Udubasa, S. S.; Constantinescu, S.; Popescu-Pogrion, N.; Feder, M.; Udubasa, G.

    2010-03-01

    Two types of ores were selected for the investigation of the fate of the ore minerals during relatively long time of residence in the waste dumps (active mining: 25 years ago in the Badeanca Valley and some 50 years ago in the Valea lui Stan area). The pentametallic ores (Co-Ni-Bi-Ag-U) in the Leaota Mts. contain a great number of primary minerals of Cu, As etc. Although the waste dumps materials have whitish-yellowish colors their NGR spectra show the presence of iron minerals very finely dispersed. In the gold ores of Valea lui Stan deposit numerous minerals were identified, such as arsenopyrite, pyrite, pyrrhotite, etc., as major gold bearing sulfides. The waste dumps materials naturally show different mineral constituents, with clay minerals as major phases. Detailed NGR investigations show however Mössbauer spectra pointing out the presence of finely dispersed iron or iron-bearing minerals. Under supergene conditions gold is commonly sequestrated by iron hydroxydes; further TEM/SAED and XRD investigations are contributing to localize the gold. In some samples Mössbauer spectra resembling those of greigite have been obtained. Greigite is also a principal concentrator of gold under supergene conditions.

  17. Tandem transmission/reflection mode XRD instrument including XRF for in situ measurement of Martian rocks and soils

    NASA Astrophysics Data System (ADS)

    Delhez, Robert; Van der Gaast, S. J.; Wielders, Arno; de Boer, J. L.; Helmholdt, R. B.; van Mechelen, J.; Reiss, C.; Woning, L.; Schenk, H.

    2003-02-01

    The mineralogy of the surface material of Mars is the key to disclose its present and past life and climates. Clay mineral species, carbonates, and ice (water and CO2) are and/or contain their witnesses. X-ray powder diffraction (XRPD) is the most powerful analytical method to identify and quantitatively characterize minerals in complex mixtures. This paper discusses the development of a working model of an instrument consisting of a reflection mode diffractometer and a transmission mode CCD-XRPD instrument, combined with an XRF module. The CCD-XRD/XRF instrument is analogous to the instrument for Mars missions developed by Sarrazin et al. (1998). This part of the tandem instrument enables "quick and dirty" analysis of powdered (!) matter to monitor semi-quantitatively the presence of clay minerals as a group, carbonates, and ices and yields semi-quantitative chemical information from X-ray fluorescence (XRF). The reflection mode instrument (i) enables in-situ measurements of rocks and soils and quantitative information on the compounds identified, (ii) has a high resolution and reveals large spacings for accurate identification, in particular of clay mineral species, and (iii) the shape of the line profiles observed reveals the kind and approximate amounts of lattice imperfections present. It will be shown that the information obtained with the reflection mode diffractometer is crucial for finding signs of life and changes in the climate on Mars. Obviously this instrument can also be used for other extra-terrestrial research.

  18. The unusual Lovina Ataxite: Examination of Meteoritic Microstructures and Terrestrial Weathering by ?XRD, Petrography, SEM, INAA and sXRF.

    NASA Astrophysics Data System (ADS)

    Flemming, R. L.; McCausland, P. J.; Kissin, S. A.; Corcoran, P. L.; Biesinger, M. C.; McIntyre, N. S.; Fuller, M. L.; Feng, R.

    2009-05-01

    The football-sized 8.2 kg Lovina ataxite is a newly classified iron meteorite that was found in Bali, Indonesia in 1981. Its unusual appearance and strong weathering have, over the years, precluded its being identified as a meteorite. Remarkable features include cm-sized pyramidal projections, or ziggurats, with mm-spaced ribs on its top surface (orientation as discovered) and deep vugs in its lower surfaces. In situ examination of Lovina's weathered ziggurats by micro X-ray diffraction (?XRD revealed that they consisted of two iron alloys: Ni-rich taenite and very Ni-rich awaruite (Ni3Fe). Although this texture is reminiscent of Widmanstätten pattern, kamacite was not observed. Magnetite was frequently observed in association with awaruite, indicating very intense weathering. Micro-XRD of several locations on a polished thin section cut near the weathered surface and a freshly polished surface of Lovina, free of weathering, revealed primarily taenite with minor troilite. Measurement of bulk grain density by He-pycnometry for the 32.5 g type specimen (cut end piece) of Lovina and other iron meteorites found that Lovina's grain density of 7.00+/- 0.02 g/cm3 was significantly less than those found for Canyon Diablo (7.37+/-0.01) and a slightly weathered Mundrabilla fragment (7.20+/-0.01), measurably reflecting the presence of the lower-density weathering products in Lovina. The presence of taenite and troilite suggested that Lovina was an ataxite, as confirmed by correlated SEM X-ray maps, petrographic and bulk INAA analysis. X-ray maps of the thin section confirmed the identities of magnetite, troilite, massive taenite, and located Ni enrichment (awaruite) in the alloy surrounding magnetite in severely weathered areas. Petrographic observations indicated the taenite to be massive, lacking exsolved kamacite spindles, daubreelite and Neumann bands, which are commonly present in ataxites. Abundant globular troilite nodules up to 0.8 mm in diameter are present. Many of the nodules are partially or totally oxidized to Fe oxides. Analysis by INAA revealed Lovina to have a composition outside the range of most grouped ataxites in group IVB. Thus, Lovina is an ungrouped ataxite. Lovina resembles other ungrouped ataxites, e.g. N'Goureyma, in its abundance of troilite nodules with a very low abundance of kamacite spindles and daubreelite, but differs in composition. Lovina's high Ni- and low Ir-content is similar to that of some ungrouped ataxites, but it differs in its relatively high Ge and Ga contents. The ziggurat structure is attributed to differential weathering within a taenite microstructure. In an effort to identify microstructures, synchrotron X-ray Fluorescence (sXRF) data have been collected using the Very sensitive Elemental and Structural Probe Employing Radiation by a Synchrotron (VESPERS) beamline at CLS. Synchrotron X-ray maps have revealed non-uniform Ni distribution across the taenite, which had appeared to be massive by petrography and SEM. This may correlate with the differential weathering behaviour of the Lovina ataxite.

  19. Characterizing the Phyllosilicate Component of the Sheepbed Mudstone in Gale Crater, Mars Using Laboratory XRD and EGA

    NASA Technical Reports Server (NTRS)

    Rampe, E. B.; Morris, R. V.; Ming, D. W.; Archer, P. D.; Bish, D. L.; Chipera, S. J.; Vaniman, D. T.; Blake, D. F.; Bristow, T. F.; Sutter, B.; Farmer, J. D.; Downs, R. T.; Leveille, R.; Achilles, C. A.; Crisp, J. A.; Des Marais, D. J.; Morookian, J. M.; Morrison, S. M.; Sarrazin, P. C.; Spanovich, N.; Treiman, A. H.; Yen, A. S.

    2014-01-01

    The Curiosity rover investigated the mineralogy of the Sheepbed mudstone member of the Yellowknife Bay formation in Gale crater. Data from the Chemistry and Mineralogy (CheMin) X-ray diffractometer (XRD) helped identify phyllosilicates in the two drilled samples, John Klein and Cumberland. These patterns showed peaks at low angles, consistent with (001) peaks in 2:1 swelling phyllosilicates [1]. Evolved gas analyses (EGA) by the Sample Analysis at Mars (SAM) instrument of these samples confirmed the presence of phyllosilicates through the release of H2O at high temperatures, consistent with dehydroxylation of octahedral OH in phyllosilicates [2]. CheMin data for the phyllosilicates at John Klein and Cumberland show that they are structurally similar in that their (02l) peaks are near 22.5 deg 2theta, suggesting both samples contain trioctahedral 2:1 phyllosilicates [1]. However, the positions of the (001) peaks differ: the phyllosilicate at John Klein has its (001) peak at 10 Angstroms, whereas the phyllosilicate at Cumberland has an (001) peak at 14 Angstroms. Such differences in (001) dspacings can be ascribed to the type of cation in the interlayer site [3]. For example, large monovalent cations (e.g., K(+)) have low hydration energies and readily lose their H2O of hydration, whereas small divalent cations (e.g., Mg(2+)) have high energies of hydration and retain H2O in the phyllosilicate interlayers [3,4]. The goal of this study is to determine whether differences in the interlayer cation composition can explain the CheMin data from John Klein and Cumberland and to use this knowledge to better understand phyllosilicate formation mechanisms.

  20. The observation of the physicochemical change of rock under freeze-thawing experiment: CLSM, XRD and ICP analysis

    NASA Astrophysics Data System (ADS)

    Choi, J.; Chae, B.; Chon, C.; Jeong, J.

    2013-12-01

    Abstract : In order to understand the progress of the physical weathering of rock sample, we managed freeze-thawing experiment at temperature of up to 40C from -20C taking into account of South Korea. In this study, the time was held by two hours the temperature of the maximum (40C) and minimum (-20C) and the experiments were carried out at intervals of one hour rising and falling. We have run the experiment about 120 cycle with the cycle of -20C from 40C experiment. We measured the physical properties of rock samples after each 20 cycle has elapsed by using confocal laser scanning microscope (CLSM) and observed changes in roughness of rock samples surface. We also analyzed the mineral of rock sample using the XRD analysis and observing the change in chemical composition of solution used in the experiment by using ICP analysis. Through the above process, we observed physico-chemical changes in the rock sample due to freeze-thaw cycles. To analysis of the line roughness parameter we used set by the 10 vertical and horizontal cross section line on the surface and surface roughness parameter was analyzed by using the area on the surface. Through such a process, while the freeze-thawing experiment is advanced, it was studied how the physical roughness and chemical composition were changed. As a result, it was possible to observe a change in the mineral component of the particular dissolved in the solution and it was able to observe the characteristic changes of the parameters of the roughness of the lines and surfaces.

  1. Bone matrix calcification during embryonic and postembryonic rat calvarial development assessed by SEM-EDX spectroscopy, XRD, and FTIR spectroscopy.

    PubMed

    Henmi, Akiko; Okata, Hiroshi; Anada, Takahisa; Yoshinari, Mariko; Mikami, Yasuto; Suzuki, Osamu; Sasano, Yasuyuki

    2016-01-01

    Bone mineral is constituted of biological hydroxyapatite crystals. In developing bone, the mineral crystal matures and the Ca/P ratio increases. However, how an increase in the Ca/P ratio is involved in maturation of the crystal is not known. The relationships among organic components and mineral changes are also unclear. The study was designed to investigate the process of calcification during rat calvarial bone development. Calcification was evaluated by analyzing the atomic distribution and concentration of Ca, P, and C with scanning electron microscopy (SEM)-energy-dispersive X-ray (EDX) spectroscopy and changes in the crystal structure with X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. Histological analysis showed that rat calvarial bone formation started around embryonic day 16. The areas of Ca and P expanded, matching the region of the developing bone matrix, whereas the area of C became localized around bone. X-ray diffraction and FTIR analysis showed that the amorphous-like structure of the minerals at embryonic day 16 gradually transformed into poorly crystalline hydroxyapatite, whereas the proportion of mineral to protein increased until postnatal week 6. FTIR analysis also showed that crystallization of hydroxyapatite started around embryonic day 20, by which time SEM-EDX spectroscopy showed that the Ca/P ratio had increased and the C/Ca and C/P ratios had decreased significantly. The study suggests that the Ca/P molar ratio increases and the proportion of organic components such as proteins of the bone matrix decreases during the early stage of calcification, whereas crystal maturation continues throughout embryonic and postembryonic bone development. PMID:25773047

  2. High temperature XRD of Cu{sub 2.1}Zn{sub 0.9}SnSe{sub 4}

    SciTech Connect

    Chetty, Raju Mallik, Ramesh Chandra

    2014-04-24

    Quaternary compound with chemical composition Cu{sub 2.1}Zn{sub 0.9}SnSe{sub 4} is prepared by solid state synthesis. High temperature XRD (X-Ray Diffraction) of this compound is used in studying the effect of temperature on lattice parameters and thermal expansion coefficients. Thermal expansion coefficient is one of the important quantities in evaluating the Grüneisen parameter which further useful in determining the lattice thermal conductivity of the material. The high temperature XRD of the material revealed that the lattice parameters as well as thermal expansion coefficients of the material increased with increase in temperature which confirms the presence of anharmonicty.

  3. Use of an ultrasonic/sonic driller/corer to obtain sample powder for chemin, a combined XRD/XRF instrument.

    SciTech Connect

    Chipera, S. J.; Bish, D. L.; Vaniman, D. T.; Sherrit, S.; Bar-Cohen, Yoseph; Blake, D.

    2003-01-01

    One of the technical issues that must be addressed before landing an XRD,iXRF spectrometer on an extraterrestrial body is how best to obtain a representative sample powder for analysis. For XRD powder diffraction analyses, it is beneficial to have a powder that is extremely fine grained to reduce preferred orientation effects and to provide a statistically significant number of crystallites to the Xray beam. Although a 2 dimensional detector as used in the CHEMIN instrument will produce good results with poorly prepared powders, the quality of the data will improve with the quality of the sample powder.

  4. Characterization of magnetic material in the mound-building termite Macrotermes gilvus in Southeast Asia

    NASA Astrophysics Data System (ADS)

    Esa, Mohammad Faris Mohammad; Rahim, Faszly; Hassan, Ibrahim Haji; Hanifah, Sharina Abu

    2015-09-01

    Magnetic material such as magnetite are known as particles that respond to external magnetic field with their ferromagnetic properties as they are believed contribute to in responding to the geomagnetic field. These particles are used by terrestrial animals such as termites for navigation and orientation. Since our earth react as giant magnetic bar, the magnitude of this magnetic field present by intensity and direction (inclination and direction). The magnetic properties and presence of magnetite in termites Macrotermes gilvus, common mound-building termite were tested. M. gilvus termites was tested with a Vibrating Sample Magnetometer VSM to determine the magnetic properties of specimen. The crushed body sample was characterized with X-Ray Diffraction XRD to show the existent of magnetic material (magnetite) in the specimens. Results from VSM indicate that M. gilvus has diamagnetism properties. The characterization by XRD shows the existent of magnetic material in our specimen in low concentration.

  5. Conduction and magnetization improvement of BiFeO{sub 3} multiferroic nanoparticles by Ag{sup +} doping

    SciTech Connect

    Ahmed, M.A.; Mansour, S.F.; El-Dek, S.I.; Abu-Abdeen, M.

    2014-01-01

    Graphical abstract: HRTEM micrographs of the samples BiFeO{sub 3}. - Highlights: • Flash auto combustion method was successful in the preparation of Ag doped BiFeO{sub 3} in nanosize. • Ag doping results in hexagonal platelet shapes up to x = 0.10, at x ? 0.15 needle shape predominates. • Mixed conduction is obtained in Ag doped samples. • This nanometric multiferroic could be recommended as attractive cathode for solid oxide fuel cell. - Abstract: Nanometric multiferroic namely Ag doped (BiFeO{sub 3}) was synthesized using flash auto combustion technique and glycine as a fuel. Single phase rhombohedral–hexagonal perovskite structure was obtained by annealing at 550 °C, as determined from XRD. High resolution transmission electron microscope (HRTEM) clarifies the hexagonal platelet shape with size 17.9 nm. Maximum room temperature AC conductivity was obtained at Ag content of x = 0.10. The results of this study promote the use of such multiferroic in solid oxide fuel cell applications.

  6. Novodneprite (AuPb3), anyuiite [Au(Pb, Sb)2] and gold micro- and nano-inclusions within plastically deformed mantle-derived olivine from the Lherz peridotite (Pyrenees, France): a HRTEM-AEM-EELS study

    NASA Astrophysics Data System (ADS)

    Ferraris, Cristiano; Lorand, Jean-Pierre

    2015-02-01

    To contribute the problem of the missing ("invisible") gold fraction in mantle rocks, olivine grains separated from orogenic lherzolite of the peridotite body of Lherz (Eastern Pyrenees, France) have been investigated by transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). The results indicate the presence of micrometric inclusions of novodneprite, AuPb3, and anyuiite, Au(Pb,Sb)2, together with nanometric clusters of metallic gold. Both minerals have been recognised on TEM images as darker contrast inclusions and identified through selected area electron diffraction (SAED) and energy dispersive spectroscopy (EDS) analyses. Gold clusters have been indirectly identified in randomly distributed nano-sized rectangular areas that occur in TEM images obtained from the edges of olivine crystals. Within these volumes the EDS analyses reveal a constant presence of Au (0.1-0.2 wt %). High-resolution TEM (HRTEM) investigations evidence series of regularly alternating sigmoidal and ellipsoidal domains developed along [110]. The EELS investigations revealed that the Au signal (M-series lines) arises from the ellipsoidal domains. It is proposed that novodneprite and anyuiite are the result of subsolidus recrystallization of the Pyrenean lherzolites accompanied by a secondary olivine grains growth that trapped inter-granular components. Likely, a process of plastic deformation favoured the formation of edge dislocations within olivine grains and thus, the circulation through them of Au-enriched fluids. A mass balance calculation of the missing gold percentage within this lherzolite points to olivine as one of the potential hosts for about the 80 % of the "invisible" gold in form of nano-inclusions, whereas only 20 % of the whole-rock Au-budget, would be hosted within assemblages of Cu-Fe-Ni sulphides.

  7. Structural and magnetic properties of nano-crystalline Ag + doped NiFe 2O 4

    NASA Astrophysics Data System (ADS)

    Ahmed, M. A.; El-Dek, S. I.; El-Kashef, I. M.; Helmy, N.

    2011-05-01

    Ni ferrite nanoparticles were prepared using citrate method. XRD pattern revealed the formation of the samples as synthesized in the spinel cubic structure. Silver doping effect on the magnetic properties of Ni ferrite was investigated. The lattice parameter was slightly increased while the values of the Curie temperature decreased with increasing Ag content. The magnetic susceptibility was measured using Faraday's method and the calculated magnetic constants were reported. The data showed that ?M and effective magnetic moment decrease with increasing Ag content.

  8. Interplay of structural, optical and magnetic properties in Gd doped CeO2

    NASA Astrophysics Data System (ADS)

    Soni, S.; Kumar, Sudish; Meena, R. S.; Vats, V. S.; Dalela, S.

    2015-06-01

    In this research wok systematic investigation on the synthesis, characterization, optical and magnetic properties of Ce1-xGdxO2 (where x=0.02, 0.04, 0.06, and 0.10) synthesized using the Solid-state method. Structural, Optical and Magnetic properties of the samples were investigated by X-ray diffraction (XRD), UV-VIS-NIR spectroscopy and VSM. Fluorite structure is confirmed from the XRD measurement on Gd doped CeO2 samples. Magnetic studies showed that the Gd doped polycrystalline samples display room temperature ferromagnetism and the ferromagnetic ordering strengthens with the Gd concentration.

  9. Interface charge transfer in polypyrrole coated perovskite manganite magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Pana, O.; Soran, M. L.; Leostean, C.; Macavei, S.; Gautron, E.; Teodorescu, C. M.; Gheorghe, N.; Chauvet, O.

    2012-02-01

    Different hybrid structures were obtained by coating magnetic nanoparticles of perovskite type manganite at optimal doping (La0.67Sr0.33MnO3,LSMO) with different quantities of polypyrrole (PPy). The amorphous layer of polypyrrole surrounding the crystalline magnetic core was observed by high resolution transmission electron microscopy (HRTEM) and analyzed by using X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) measurements in near edge structure (XANES) techniques. By analyzing the magnetic behavior of the samples one can observe that the surface modification of magnetic nanoparticles by PPy results in an increase in the saturation magnetization of the composites. The process is ascribed to paired electrons transferred from the delocalized ? states of the PPy into the outer disordered layers of the manganite. The analysis of pre-edge peak of the Mn K-edge XANES spectra in the case of PPy coated LSMO nanoparticles indicates that the charge transfer between polymer and nanoparticles is (directed) going to missing or distorted oxygen positions, hence increasing the 3d electrons' mobility and orbital hybridization between the neighboring manganese ion. As a consequence, within the surface layers of LSMO nanoparticles, both energy bands disrupted the structure, and the double exchange process between Mn ions was reestablished determining the saturation magnetizations and pre-edge features increase, respectively.

  10. XRD and mineralogical analysis of gypsum dunes at White Sands National Monument, New Mexico and applications to gypsum detection on Mars

    NASA Astrophysics Data System (ADS)

    Lafuente, B.; Bishop, J. L.; Fenton, L. K.; King, S. J.; Blake, D.; Sarrazin, P.; Downs, R.; Horgan, B. H.

    2013-12-01

    A field portable X-ray Diffraction (XRD) instrument was used at White Sands National Monument to perform in-situ measurements followed by laboratory analyses of the gypsum-rich dunes and to determine its modal mineralogy. The field instrument is a Terra XRD (Olympus NDT) based on the technology of the CheMin (Chemistry and Mineralogy) instrument onboard the Mars Science Laboratory (MSL) rover Curiosity which is providing the mineralogical and chemical composition of scooped soil samples and drilled rock powders collected at Gale Crater [1]. Using Terra at White Sands will contribute to 'ground truth' for gypsum-bearing environments on Mars. Together with data provided by VNIR spectra [2], this study clarifies our understanding of the origin and history of gypsum-rich sand dunes discovered near the northern polar region of Mars [3]. The results obtained from the field analyses performed by XRD and VNIR spectroscopy in four dunes at White Sands revealed the presence of quartz and dolomite. Their relative abundance has been estimated using the Reference Intensity Ratio (RIR) method. For this study, particulate samples of pure natural gypsum, quartz and dolomite were used to prepare calibration mixtures of gypsum-quartz and gypsum-dolomite with the 90-150?m size fractions. All single phases and mixtures were analyzed by XRD and RIR factors were calculated. Using this method, the relative abundance of quartz and dolomite has been estimated from the data collected in the field. Quartz appears to be present in low amounts (2-5 wt.%) while dolomite is present at percentages up to 80 wt.%. Samples from four dunes were collected and prepared for subsequent XRD analysis in the lab to estimate their composition and illustrate the changes in mineralogy with respect to location and grain size. Gypsum-dolomite mixtures: The dolomite XRD pattern is dominated by an intense diffraction peak at 2??36 deg. which overlaps a peak of gypsum, This makes low concentrations of dolomite difficult to quantify in mixtures with high concentration of gypsum. Dolomite has been detected in some locations at dune 3 as high as 80 wt.%. Gypsum-quartz mixtures: The intensity of the main diffraction peak of quartz at 2??31 deg. decreases progressively with the decrease of the amount of quartz in the mixtures. Samples from dune 1 and 2 show quartz abundance at 5.6 and 2.6 wt.% respectively . [1] Blake et al. Space Sci. Rev. (2012). doi:10.1007/s11214-012-9905-1. [2] King et al. (2013) AGU, submitted. [3] Langevin et al. (2005). Science 307, 1584-1586.

  11. Exchange bias in ferrite hollow nanoparticles originated by complex internal magnetic structure

    NASA Astrophysics Data System (ADS)

    De Biasi, Emilio; Lima, Enio, Jr.; Vargas, Jose M.; Zysler, Roberto D.; Arbiol, Jordi; Ibarra, Alfonso; Goya, Gerardo F.; Ibarra, M. Ricardo

    2015-10-01

    Iron-oxide hollow nanospheres (HNS) may present unusual magnetic behavior as a consequence of their unique morphology. Here, we report the unusual magnetic behavior of HNS that are 9 nm in diameter. The magnetic properties of HNS originate in their complex magnetic structure, as evidenced by Mössbauer spectroscopy and magnetization measurements. We observe a bias in the hysteresis when measured at very low temperature in the field cooling protocol (10 kOe). In addition, dc (static) and ac (dynamic) magnetization measurements against temperature and applied field reveal a frustrated order of the system below 10 K. High-resolution transmission electron microscopy (HRTEM) studies reveal that the HNS are composed of small crystalline clusters of about 2 nm in diameter, which behave as individual magnetic entities. Micromagnetic simulations (using conjugate gradient in order to minimize the total energy of the system) reproduce the experimentally observed magnetic behavior. The model considers the hollow particles as constituted by small ordered clusters embedded in an antiferromagnetic environment (spins localized outside the clusters). In addition, the surface spins (in both inner and outer surfaces of the HNS) are affected by a local surface anisotropy. The strong effective magnetic anisotropy field of the clusters induces the bias observed when the system is cooled in the presence of a magnetic external field. This effect propagates through the exchange interaction into the entire particle.

  12. Magnetite and magnetite/silver core/shell nanoparticles with diluted magnet-like behavior

    NASA Astrophysics Data System (ADS)

    Garza-Navarro, Marco; Torres-Castro, Alejandro; González, Virgilio; Ortiz, Ubaldo; De la Rosa, Elder

    2010-01-01

    In the present work is reported the use of the biopolymer chitosan as template for the preparation of magnetite and magnetite/silver core/shell nanoparticles systems, following a two step procedure of magnetite nanoparticles in situ precipitation and subsequent silver ions reduction. The crystalline and morphological characteristics of both magnetite and magnetite/silver core/shell nanoparticles systems were analyzed by high resolution transmission electron microscopy (HRTEM) and nanobeam diffraction patterns (NBD). The results of these studies corroborate the core/shell morphology and the crystalline structure of the magnetite core and the silver shell. Moreover, magnetization temperature dependent, M( T), measurements show an unusual diluted magnetic behavior attributed to the dilution of the magnetic ordering in the magnetite and magnetite/silver core/shell nanoparticles systems.

  13. Magnetic properties of Ni and Cu-Ni nanoparticles

    NASA Astrophysics Data System (ADS)

    Ganga, B. G.; Santhosh, P. N.; Thomas, P. John

    2012-06-01

    Ni and Cu-Ni nanoparticles were prepared by solution phase method and crystal phase was identified by XRD. SEM and EDX were used to analyze morphology and elemental composition of nanoparticles. Magnetic measurements indicate that Ni nanoparticles are superparamagnetic at room temperature and blocking temperature is around 103 K. Ferromagnetism is observed in the case of Cu-Ni nanoparticles with decrease in magnetization compared to Ni nanoparticles.

  14. The coercivity mechanism of sintered SM(CobalFe0.245Cu0.07Zr0.02)7.8 permanent magnets with different isothermal annealing time

    NASA Astrophysics Data System (ADS)

    Sun, Wei; Zhu, Minggang; Guo, Zhaohui; Fang, Yikun; Li, Wei

    2015-11-01

    Precipitation-hardened 2:17-type SmCo permanent magnet has attracted much attention due to its high Curie temperature and excellent magnetic properties. Sm(CobalFe0.245Cu0.07Zr0.02)7.8 (at%) sintered magnets with high remanence (Br ~1.15 T) were prepared using a traditional powder metallurgy method. The intrinsic coercivity Hcj of the magnets was increased from 429 to 994 kA m-1 with isothermal annealing time increasing from 10 to 40 h, which is different from the phenomenon that increasing aging time leads to a reduced coercivity mentioned in the Ref. [16]. In consideration of rarely report about the microstructure of the final magnet isothermally annealed for 40 h, we have tried to originally analyze the relationship between the microstructure and the magnetic properties. Besides, the lattice constants of sintered Sm(CobalFe0.245Cu0.07Zr0.02)7.8 permanent magnet isothermally annealed for 40 h have been given by indexing the HRTEM results including the selected area electron diffraction (SAED) and HRTEM images.

  15. Magnetic interaction in oxygenated alpha Fe-phthalocyanines

    SciTech Connect

    Kuzmann, Ern? Homonnay, Zoltán; Horváth, Attila; Pechousek, Jiri; Cuda, Jan; Machala, Libor; Zoppellaro, Giorgio; Zboril, Radek; Klencsár, Zoltán; Kubuki, Shiro; Nath, Amar

    2014-10-27

    Alpha iron phthalocyanines (?-FePc) oxygenated at low temperatures were investigated with the help of {sup 57}Fe Mössbauer spectroscopy, magnetization measurements (SQUID) and X-ray diffractometry (XRD). Mössbauer spectroscopy revealed that upon oxygenation of ?-FePc, new species were formed which could be associated with Fe{sup III}Pc oxygen adducts. Unexpectedly, magnetically split spectrum of oxygenated ?-FePc was observed below 20 K. In-field Mössbauer spectra in a 5 T external magnetic field at 5K and magnetization measurements indicate antiferromagnetic coupling in oxygenated ?-FePc.

  16. Quantitative assessment of alkali-reactive aggregate mineral content through XRD using polished sections as a supplementary tool to RILEM AAR-1 (petrographic method)

    SciTech Connect

    Castro, Nelia; Sorensen, Bjorn E.; Broekmans, Maarten A.T.M.

    2012-11-15

    The mineral content of 5 aggregate samples from 4 different countries, including reactive and non-reactive aggregate types, was assessed quantitatively by X-ray diffraction (XRD) using polished sections. Additionally, electron probe microanalyzer (EPMA) mapping and cathodoluminescence (CL) were used to characterize the opal-CT identified in one of the aggregate samples. Critical review of results from polished sections against traditionally powdered specimen has demonstrated that for fine-grained rocks without preferred orientation the assessment of mineral content by XRD using polished sections may represent an advantage over traditional powder specimens. Comparison of data on mineral content and silica speciation with expansion data from PARTNER project confirmed that the presence of opal-CT plays an important role in the reactivity of one of the studied aggregates. Used as a complementary tool to RILEM AAR-1, the methodology suggested in this paper has the potential to improve the strength of the petrographic method.

  17. Determination of the Al Composition of Al{sub x}Ga{sub 1-x}N Thin Films By Means Of EDX and XRD Techniques

    SciTech Connect

    Ng, S. S.; Hassan, Z.; Hassan, H. Abu

    2010-07-07

    In this paper, the determinations of Al composition x of Al{sub x}Ga{sub 1-x}N(0{<=}x{<=}1) thin films by means of the energy dispersive X-ray (EDX) and X-ray diffraction (XRD) analyses are reported. Through these non-destructive and contactless techniques, a large probed area of the Al{sub x}Ga{sub 1-x}N samples can be selected. Consequently, the uncertainty due to the inhomogeneity of the Al composition can be avoided. For EDX measurements, the Al composition is calculated based on the weight percent of the Al and Ga elements, while that in the XRD measurements is based on lattice constant c and Vegard's law. The results from these two independent techniques are in good agreement with each other.

  18. Synthesis, characterisation, spectral, thermal, XRD, molecular modelling and potential antibacterial study of metal complexes containing octadentate azodye ligands

    NASA Astrophysics Data System (ADS)

    Mahapatra, Bipin Bihari; Chaulia, Satyanarayan; Sarangi, Ashish Kumar; Dehury, Satyanarayan; Panda, Jnyanaranjan

    2015-05-01

    Twelve tetrametallic complexes of Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) with two new octadentate azodye ligands, 4,4?-bis(2?,4?-dihydroxy-5?carboxyphenylazo) diphenylether (LH6) and 4,4?-bis(2?,4?-dihydroxy-5?-acylphenylazo) diphenylether (L?H4) have been synthesised. The structural elucidation of the complexes was made basing upon analytical, conductance, magnetic susceptibility, IR, electronic spectra, ESR, NMR, ESI-MS, TG, DTG, DTA and X-ray diffraction (powder pattern) data. The cobalt (II) and nickel (II) complexes are found to be octahedral, copper (II) complexes are distorted octahedral and a tetrahedral stereochemistry has been suggested to zinc (II), cadmium (II) and mercury (II) complexes. The thermal analysis data provided the kinetic parameters as order of decomposition reaction, activation energy and frequency factor. The geometry of the ligands and their Co(II), Ni(II), Cu(II) and Zn(II) complexes were optimised and their physicochemical properties were calculated by using molecular modelling procedure. The ESI-MS determination supports the molecular formula and molecular weight of the ligands and the complexes. The Ni(II) complex is found to have a triclinic crystal system. The potential antibacterial study of the two ligands and eight metal complexes was made by cup-plate method against one gram positive and one gram negative bacteria. The results showed increase in the activity of some metal complexes as compare with azodye ligands.

  19. Characterizing the Phyllosilicates and Amorphous Phases Found by MSL Using Laboratory XRD and EGA Measurements of Natural and Synthetic Materials (Invited)

    NASA Astrophysics Data System (ADS)

    Rampe, E. B.; Morris, R. V.; Chipera, S.; Bish, D. L.; Bristow, T.; Archer, P. D.; Blake, D.; Achilles, C.; Ming, D. W.; Vaniman, D.; Crisp, J. A.; Des Marais, D. J.; Downs, R.; Farmer, J. D.; Morookian, J.; Morrison, S.; Sarrazin, P.; Spanovich, N.; Treiman, A. H.; Yen, A. S.; Team, M.

    2013-12-01

    The Curiosity Rover landed on the Peace Vallis alluvial fan in Gale crater on August 5, 2012. A primary mission science objective is to search for past habitable environments, and, in particular, to assess the role of past water. Identifying the minerals and mineraloids that result from aqueous alteration at Gale crater is essential for understanding past aqueous processes at the MSL landing site and hence for interpreting the site's potential habitability. X-ray diffraction (XRD) data from the CheMin instrument and evolved gas analyses (EGA) from the SAM instrument have helped the MSL science team identify phases that resulted from aqueous processes: phyllosilicates and amorphous phases were measure in two drill samples (John Klein and Cumberland) obtained from the Sheepbed Member, Yellowknife Bay Fm., which is believed to represent a fluvial-lacustrine environment. A third set of analyses was obtained from scoop samples from the Rocknest sand shadow. Chemical data from the APXS instrument have helped constrain the chemical compositions of these secondary phases and suggest that the phyllosilicate component is Mg-enriched and the amorphous component is Fe-enriched, relatively Si-poor, and S- and H-bearing. To refine the phyllosilicate and amorphous components in the samples measured by MSL, we measured XRD and EGA data for a variety of relevant natural terrestrial phyllosilicates and synthetic mineraloids in laboratory testbeds of the CheMin and SAM instruments. Specifically, Mg-saturated smectites and vermiculites were measured with XRD at low relative humidity to understand the behavior of the 001 reflections under Mars-like conditions. Our laboratory XRD measurements suggest that interlayer cation composition affects the hydration state of swelling clays at low RH and, thus, the 001 peak positions. XRD patterns of synthetic amorphous materials, including allophane, ferrihydrite, and hisingerite were used in full-pattern fitting (FULLPAT) models to help determine the types and abundances of amorphous phases in the martian rocks and sand shadow. These models suggest that the rocks and sand shadow are composed of ~30% amorphous phases. Sulfate-adsorbed allophane and ferrihydrite were measured by EGA to further understand the speciation of the sulfur present in the amorphous component. These data indicate that sulfate adsorbed onto the surfaces of amorphous phases could explain a portion of the SO2 evolution in the Rocknest SAM data. The additional constraints placed on the mineralogy and chemistry of the aqueous alteration phases through our laboratory measurements can help us better understand the nature of the fluids that affected the different samples and devise a history of aqueous alteration for the Sheepbed Member of the Yellowknife Bay Fm. at Gale crater.

  20. Microstructure of multistage annealed nanocrystalline SmCo2Fe2B alloy with enhanced magnetic properties

    SciTech Connect

    Jiang, Xiujuan; Devaraj, Arun; Balamurugan, B.; Cui, Jun; Shield, Jeffrey E.

    2014-07-30

    The microstructure and chemistry of SmCo2Fe2B melt-spun alloy after multistage annealing was investigated using high resolution transmission electron microscopy (HRTEM) and 3D atom probe tomography. The multistage annealing resulted in an increase in both the coercivity and magnetization. The presence of Sm(Co,Fe)4B (1:4:1) and Sm2(Co,Fe)17Bx (2:17:x) magnetic phases were confirmed using both techniques. Fe2B at a scale of 􏰫5 nm was found by HRTEM precipitating within the 1:4:1 phase after the second-stage annealing. Ordering within the 2:17:x phase was directly identified both by the presence of antiphase boundaries observed by TEM and the interconnected isocomposition surface network found in 3D atom probe results in addition to radial distribution function analysis. The variations in the local chemistry after the secondary annealing were considered pivotal in improving the magnetic properties.

  1. Microstructure of Multistage Annealed Nanocrystalline SmCo2Fe2B Alloy with Enhanced Magnetic Properties

    SciTech Connect

    Jiang, Xiujuan; Devaraj, Arun; Balamurugan, B.; Cui, Jun; Shield, Jeffrey E.

    2014-02-14

    The microstructure and chemistry of SmCo2Fe2B melt-spun alloy after multistage annealing was investigated using high resolution transmission electron microscopy (HRTEM) and 3D atom probe tomography. The multistage annealing resulted in an increase in both the coercivity and magnetization. The presence of Sm(Co,Fe)4B (1:4:1) and Sm2(Co,Fe)17Bx (2:17:x) magnetic phases were confirmed using both techniques. Fe2B at a scale of ?5?nm was found by HRTEM precipitating within the 1:4:1 phase after the second-stage annealing. Ordering within the 2:17:x phase was directly identified both by the presence of antiphase boundaries observed by TEM and the interconnected isocomposition surface network found in 3D atom probe results in addition to radial distribution function analysis. The variations in the local chemistry after the secondary annealing were considered pivotal in improving the magnetic properties.

  2. Magnetic characterization of dual phase FeZrB soft magnetic alloy

    NASA Astrophysics Data System (ADS)

    Kong, L. H.; Chen, R. R.; Song, T. T.; Gao, Y. L.; Zhai, Q. J.

    2011-12-01

    The magnetic properties and the annealing process of Fe 78Zr 7B 15 amorphous ribbons are investigated by X-ray diffraction (XRD), differential scanning calorimetry, and vibrating sample magnetometer. The fully amorphous structure of the as-quenched ribbons is confirmed by the XRD pattern. The Curie temperature and the saturation magnetization Ms of the ribbons are 305 °C and 124.3 emu/g, respectively. Annealing at 550 °C can result in an increase in Ms with annealing time due to the increasing crystallized volume fraction of ?-Fe phase. The optimized annealing process is established at 550 °C for 20-30 min with maximum Ms of 146.6 emu/g. The morphology of the ribbons annealed at 550 °C is observed by scanning electron microscopy, showing that nanocrystalline ?-Fe grains are dispersed in an amorphous matrix.

  3. Mössbauer and XRD Studies of N0.6Cu0.2Zn0.2Ce(x)Fe2-xO4 Ferrites by Sol-Gel Auto-Combustion.

    PubMed

    Lin, Qing; Lei, Chengiong; He, Yun; Xu, JianmeI; Wang, Ruijun

    2015-04-01

    In this work, stoichiometric Ni0.6Cu0.2Zn0.2Ce(x)Fe2-xO4 ferrites with 0 ? x ? 0.85 have been prepared by Sol-Gel auto-combustion method and we have investigated the effect of impurity CeO2 phase to the microstructure and hyperfine magnetic field in spinel ferrite. The results of XRD patterns confirm that the average crystallite size of samples decreases with Ce3+ substitution increasing and the lattice parameters vary as a function of x content. 57Fe Mössbuaer spectra at room temperature for all samples confirm the [Fe(3+)-O2-Fe3+] super exchange interaction decrease due to cerium substitution. For low temperature auto-combustion samples it reveals one normal sextet line and one doublet line x ? 0.25, which show well-resolved ferromagnetic order. Lattice defects are determined and Mössbuaer spectrums vary from magnetic sextet to relaxation doublet at x > 0.45 due to a mass of CeO2 phase. In contrast, the Mössbuaer spectra for the samples sintered at 800 °C/3 h detect the secondary phase-Fe2O3 where the cation distribution occurs and it collapses to paramagnetic doublet (x ? 0.85). So Ce3+ substitution has its maximum limit values of super exchange interaction and high sintering temperature will affect this interaction. SEM shows the crystallite of the un-doped specimen sintered at 800 °C/3 h form well. PMID:26353526

  4. Magnetic Levitation.

    ERIC Educational Resources Information Center

    Rossing, Thomas D.; Hull, John R.

    1991-01-01

    Discusses the principles of magnetic levitation presented in the physics classroom and applied to transportation systems. Topics discussed include three classroom demonstrations to illustrate magnetic levitation, the concept of eddy currents, lift and drag forces on a moving magnet, magnetic levitation vehicles, levitation with permanent magnets

  5. PyXRD v0.6.2: a FOSS program to quantify disordered, layered minerals using multi-specimen X-ray diffraction profile fitting

    NASA Astrophysics Data System (ADS)

    Dumon, M.; Van Ranst, E.

    2015-03-01

    This paper presents a free and open-source model called PyXRD (short for Python X-ray diffraction) to improve the quantification of complex, poly-phasic mixed-layer phyllosilicate assemblages. The novelty of this model is the ab initio incorporation of the multi-specimen method, making it possible to share phases and (a selection of) their parameters across multiple specimens. By effectively reducing the number of parameters and increasing the number of observations, this approach speeds up the manual refinement process significantly when automated algorithms are used. To check the hypothesis that the multi-specimen set-up can improve automatic parameter refinement, we calculated X-ray diffraction patterns for four theoretical mineral assemblages. These patterns were then used as input for a refinement employing the multi-specimen set-up and one employing the single-pattern set-ups. For all of the assemblages, PyXRD was able to reproduce or approximate the input parameters with the multi-specimen approach. Diverging solutions only occurred in single-pattern set-ups which do not contain enough information (e.g. patterns of heated samples) to discern all the different minerals. Assuming a correct qualitative interpretation was made and a single pattern exists in which all phases are sufficiently discernible, the obtained results indicate a good quantification can often be obtained with just that pattern. For naturally occurring samples, this could mean modelling air-dry and/or ethylene-glycolated patterns might be sufficient. However, these results from theoretical experiments cannot automatically be extrapolated to all real-life experiments. In any case, PyXRD has proven to be very useful when X-ray diffraction patterns are modelled for complex mineral assemblages containing mixed-layer phyllosilicates with a multi-specimen approach.

  6. Effect of deposition pressure on the structural and magnetic properties of cobalt ferrite thin films

    SciTech Connect

    Nongjai, R.; Khan, S.; Ahmad, H.; Khan, I.; Asokan, K.

    2013-06-03

    We present the influence of deposition pressure on the structural and magnetic properties of cobalt ferrite thin films. Thin films of Co ferrite were deposited by rf sputtering on Si (100) substrate and characterized by X - Ray Diffraction (XRD), Atomic Force Microscopy (AFM) and Vibrating Sample Magnetometer (VSM). The XRD patterns showed the formation of crystalline single phase of the films. The particle size and surface roughness of the films were strongly influence by gas pressure. Hysteresis loops measured at room temperature showed the enhancement of magnetic properties with the increase of gas pressure which is attributed to the decrease of particle size.

  7. Effect of interparticle interactions on size determination of zirconia and silica based systems – A comparison of SAXS, DLS, BET, XRD and TEM

    PubMed Central

    Pabisch, Silvia; Feichtenschlager, Bernhard; Kickelbick, Guido; Peterlik, Herwig

    2012-01-01

    The aim of this work is a systematic comparison of size characterisation methods for two completely different model systems of oxide nanoparticles, i.e. amorphous spherical silica and anisotropic facet-shaped crystalline zirconia. Size and/or size distribution were determined in a wide range from 5 to 70 nm using small-angle X-ray scattering (SAXS), dynamic light scattering (DLS), nitrogen sorption (BET), X-ray diffraction (XRD) and transmission electron microscopy (TEM). A nearly perfect coincidence was observed only for SAXS and TEM for both types of particles. For zirconia nanoparticles considerable differences between different measurement methods were observed. PMID:22347721

  8. Neodymium Magnets.

    ERIC Educational Resources Information Center

    Wida, Sam

    1992-01-01

    Uses extremely strong neodymium magnets to demonstrate several principles of physics including electromagnetic induction, Lenz's Law, domain theory, demagnetization, the Curie point, and magnetic flux lines. (MDH)

  9. Preparation of magnetic fluorochromate hybrid nanomaterials with triphenylphosphine surface modified iron oxide nanoparticles and their characterization

    NASA Astrophysics Data System (ADS)

    Rahimi, Rahmatollah; Maleki, Ali; Maleki, Saied

    2014-04-01

    In this study, a new magnetic hybrid nanomaterial Fe3O4@SiO2@PPh3@[CrO3F]- is instituted. Firstly, magnetic Fe3O4 nanoparticles have been synthesized by hydrothermal method. Next, the produced magnetic nanoparticles were covered with a silica shell via modified Stöber method. Then, the core-shell magnetic nanoparticles system Fe3O4@SiO2 functionalization was combined by utilizing (3-chloropropyl)trimethoxysilane and triphenylphosphine, to give the cationic part for immobilization of the anionic part of the Cr(VI) catalysts including [CrO3F]-. The structure of the catalyst after immobilization was investigated by using elemental analysis, X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and solid state UV-vis. The particle size and morphology were identified by scanning electron microscope (SEM) and XRD. Magnetization properties of nanoparticles were confirmed by vibrating sample magnetometer (VSM).

  10. Magnetization and Magnetocaloric Effect in Sol-Gel Derived Nanocrystalline Copper-Zinc Ferrite.

    PubMed

    Anwar, M S; Ahmed, Faheem; Koo, Bon Heun

    2015-02-01

    We report the sol-gel synthesis and magnetocaloric effect in nanocrystalline copper-zinc ferrite (Cu0.5Zn0.5Fe2O4). The synthesized powder was characterized by using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX) and magnetization measurements. The XRD results confirm the formation of single phase spinel structure. The average particle size was found to be ~58 nm. FE-SEM results suggested that the nanoparticles are agglomerated and spherical in shape. Magnetization measurement reveals that Cu0.5Zn0.5Fe2O4 nanoparticles exhibit transition temperature (Tc) above room temperature. The maximum magnetic entropy change (?SM)max shows interesting behaviour and was found to vary with the applied magnetic field. This nanopowder can be considered as potential material for magnetic refrigeration above room temperature. PMID:26353670

  11. Mechanism of Rhabdophane-(La) And Lanthanite-(La) Formation during Reduction of Bioavailabe Nutrients in Water based on SEM and XRD Study

    NASA Astrophysics Data System (ADS)

    Szopa, Krzysztof; Banasik, Kamila; Krzykawski, Tomasz

    2012-01-01

    This study presents results of SEM and XRD investigation of products formed after La-rich bentonite application into water containing PO43- and CO32- ions. The main product of the investigated reaction with phosphate and carbonate anions is rabdophane-(La) and lanthanite-(La), respectively. Studied material has adaptation in many water reservoirs only for phosphorus ions reduction. Further studies might find application in case of reduction others hazardous ions. They could be precipitated in the same fast and effective way, to other stable, nontoxic mineral phases. Niniejszy artyku? traktuje o mo?liwo?ci redukcji nutrientów (np. PO43-, CO32-) za pomoc? bentonitu wzbogaconego w lantan. Jak dot?d jedynym zastosowaniem wspomnianego bentonitu jest redukcja jonów fosfonowych w ?rodowiskach wodnych (np. jeziora, rzeki, zastoiska) do stabilnego i nietoksycznego zwi?zku mineralnego jakim jest rabdofan-(La). Na podstawie analiz SEM oraz XRD wykazano, ?e badany materia? umo?liwia równie? redukcj? jonów w?glanowych do stabilnej i nietoksycznej fazy mineralnej-w?glanowej (lantanit-(La)). Dalsze studia nad bentonitem lantanowym, poczynione wzgl?dem innych, niepo??danych jonów (np. jonów azotanowych czy arsenianowych) mog? przynie?? odpowiedzi wzgl?dem ewentualnego i dalszego, ?rodowiskowego zastosowania bentonitu lantanowego.

  12. Mineralogical In-situ Investigation of Acid-Sulfate Samples from the Rio Tinto River, Spain, with a Portable XRD/XRF Instrument

    NASA Technical Reports Server (NTRS)

    Sarrazin, P.; Ming, D. W.; Morris, R. V.; Fernandez-Remolar, D.; Amils, R.; Arvidson, R. E.; Blake, D.; Bish, D. L.

    2007-01-01

    A field campaign was organized in September 2006 by Centro de Astobiologica (Spain) and Washington University (St Louis, USA) for the geological study of the Rio Tinto river bed sediments using a suite of in-situ instruments comprising an ASD reflectance spectrometer, an emission spectrometer, panoramic and close-up color imaging cameras, a life detection system and NASA's CheMin 4 XRD/XRF prototype. The primary objectives of the field campaign were to study the geology of the site and test the potential of the instrument suite in an astrobiological investigation context for future Mars surface robotic missions. The results of the overall campaign will be presented elsewhere. This paper focuses on the results of the XRD/XRF instrument deployment. The specific objectives of the CheMin 4 prototype in Rio Tinto were to 1) characterize the mineralogy of efflorescent salts in their native environments; 2) analyze the mineralogy of salts and oxides from the modern environment to terraces formed earlier as part of the Rio Tinto evaporative system; and 3) map the transition from hematite-dominated terraces to the mixed goethite/salt-bearing terraces where biosignatures are best preserved.

  13. Structural and morphological characterization of Poly(o-ethoxyaniline) Emeraldine-salt form using FTIR, XRD, LeBail Method and SEM

    NASA Astrophysics Data System (ADS)

    Silva, Adriano de S.; Soares, Juliana C.; Mafud, Ana Carolina; de Souza, Sérgio M.; Fernandes, Edson G. R.; Mascarenhas, Yvonne P.; Sanches, Edgar A.

    2014-08-01

    The introduction of polar functional and alkyl groups into the main chain of Polyaniline (PANI) is a mechanism to obtain soluble polymers in a wider variety of organic solvents. Poly(o-ethoxyaniline) (POEA) is a derivative of PANI and its structural difference is the presence of the group (-OC2H5) in the ortho position of the carbon rings. Despite the large number of studies performed with PANI and its derivatives, there are few that focus on a structural study of these materials in doped form (ES). Poly(o-ethoxyaniline) Emeraldine-salt form (POEA-ES) was synthesized in polymerization times of 3, 24 and 48 h. Through XRD measurements were observed that different polymerization times did not cause structural changes in polymer structures. It were found in XRD patterns peaks at 2? = 8°, 12°, 16°, 24°, 26°, 38°, 44° and 52°. Crystallinity percentage was calculated using the Peak Fitting Module Program and showed that POEA-ES has around 39% of crystallinity. FTIR analysis allowed to identify characteristic absorption bands in the structure of POEA-ES. By Scanning Electron Microscopy (SEM) it was observed micrometric particles of varying sizes, with morphologies similar to interconnected vesicular microspheres. Through LeBail Method, it was observed that crystallites of POEA-ES are present in the order of 26 Å. It was found a conductivity value of 0.3 × 10-7 S/cm for POEA-ES.

  14. AsCl(3): from the crystalline to the liquid state. XRD (176 < T (K) < 250) and WAXS (295 K) studies.

    PubMed

    Galy, Jean; Enjalbert, Renée; Lecante, Pierre; Burian, Andrzej

    2002-02-25

    This paper presents structural studies on crystalline and liquid AsCl(3), performed using X-ray diffraction (XRD) and wide-angle X-ray scattering (WAXS) in the 176-250 K temperature range and at 295 K for the crystalline and liquid samples, respectively. The XRD results, collected using a single-crystal diffractometer, show that AsCl(3) crystallizes in the orthorhombic system with P2(1)2(1)2(1) space group and the unit cell parameters a = 9.475(3) A, b = 11.331(2) A, and c = 4.2964(8) A at 221 K. This structure is stable in the temperature range 176-243 K. Above the melting point, at 257 K, transition to the liquid state is observed. The WAXS data were recorded up to a maximum scattering vector K(max) = 16 A(-1) and then converted to real space by the sine Fourier transform, yielding to the reduced radial distribution function (RRDF). For a series of models, based on the crystalline AsCl(3) structure, the intensity and RRDF functions have been computed and compared with the experimental data. These simulations indicate that the model consisting of six AsCl(3) molecules, arranged along the y axis, accounts satisfactorily for the experimental observation. The results of the structure analysis in both crystalline and liquid states are discussed in relation to the influence of the As lone electron pair. PMID:11849068

  15. Synthesis, structural and vibrational investigation on 2-phenyl-N-(pyrazin-2-yl)acetamide combining XRD diffraction, FT-IR and NMR spectroscopies with DFT calculations

    NASA Astrophysics Data System (ADS)

    Lukose, Jilu; Yohannan Panicker, C.; Nayak, Prakash S.; Narayana, B.; Sarojini, B. K.; Van Alsenoy, C.; Al-Saadi, Abdulaziz A.

    2015-01-01

    The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 2-phenyl-N-(pyrazin-2-yl)acetamide have been investigated experimentally and theoretically using Gaussian09 software package. The title compound was optimized by using the HF/6-31G(6D,7F) and B3LYP/6-31G(6D,7F) calculations. The geometrical parameters are in agreement with the XRD data. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. Gauge-including atomic orbital 1H-NMR chemical shifts calculations were carried out and compared with experimental data. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. Molecular electrostatic potential was performed by the DFT method. First hyperpolarizability is calculated in order to find its role in non linear optics. From the XRD data, in the crystal, molecules are held together by strong Csbnd H⋯O and Nsbnd H⋯O intermolecular interactions.

  16. Thermoluminescence (TL) properties and x-ray diffraction (XRD) analysis of high purity CaSO{sub 4}:Dy TL material

    SciTech Connect

    Kamarudin, Nadira; Abdullah, Wan Saffiey Wan; Dollah, Mohd Taufik; Hamid, Muhammad Azmi Abdul

    2014-09-03

    This paper presents the characterization and TL properties of dysprosium (Dy) doped calcium sulfate (CaSO{sub 4}) TL material produced by co-precipitation technique with 0.5mol% concentration of dopant. The morphology of the produced TL material was studied using scanning electron microscope (SEM) and the micrograph shows that rectangular parallelepiped shaped crystal with the average of 150 ?m in length were produced. The crystallinity of the produced powder was studied using x-ray powder diffraction (XRD). The XRD spectra show that the TL material produced is high purity anhydrite CaSO{sub 4} with average crystallite size of 74 nm with orthorhombic crystal system. The TL behavior of produced CaSO{sub 4}:Dy was studied using a TLD reader after exposure to gamma ray by Co{sup 60} source with the doses of 1,5 and 10 Gy. The glow curve shows linear response with glow peak around 230°C which is desired development in the field of radiation dosimetry.

  17. In situ characterization of uranium and americium oxide solid solution formation for CRMP process: first combination of in situ XRD and XANES measurements.

    PubMed

    Caisso, Marie; Picart, Sébastien; Belin, Renaud C; Lebreton, Florent; Martin, Philippe M; Dardenne, Kathy; Rothe, Jörg; Neuville, Daniel R; Delahaye, Thibaud; Ayral, André

    2015-04-14

    Transmutation of americium in heterogeneous mode through the use of U1-xAmxO2±? ceramic pellets, also known as Americium Bearing Blankets (AmBB), has become a major research axis. Nevertheless, in order to consider future large-scale deployment, the processes involved in AmBB fabrication have to minimize fine particle dissemination, due to the presence of americium, which considerably increases the risk of contamination. New synthesis routes avoiding the use of pulverulent precursors are thus currently under development, such as the Calcined Resin Microsphere Pelletization (CRMP) process. It is based on the use of weak-acid resin (WAR) microspheres as precursors, loaded with actinide cations. After two specific calcinations under controlled atmospheres, resin microspheres are converted into oxide microspheres composed of a monophasic U1-xAmxO2±? phase. Understanding the different mechanisms during thermal conversion, that lead to the release of organic matter and the formation of a solid solution, appear essential. By combining in situ techniques such as XRD and XAS, it has become possible to identify the key temperatures for oxide formation, and the corresponding oxidation states taken by uranium and americium during mineralization. This paper thus presents the first results on the mineralization of (U,Am) loaded resin microspheres into a solid solution, through in situ XAS analysis correlated with HT-XRD. PMID:25742991

  18. Combined In-Situ XRD and In-Situ XANES Studies on the Reduction Behavior of a Rhenium Promoted Cobalt Catalyst

    SciTech Connect

    Kumar, Nitin; Payzant, E Andrew; Jothimurugesan, K; Spivey, James J

    2011-01-01

    A 10% Co 4% Re/(2% Zr/SiO2) catalyst was prepared by co-impregnation using a silica support modified by 2% Zr. The catalyst was characterized by temperature programmed reduction (TPR), in situ XRD and in situ XANES analysis where it was simultaneously exposed to H2 using a temperature programmed ramp. The results showed the two step reduction of large crystalline Co3O4 with CoO as an intermediate. TPR results showed that the reduction of highly dispersed Co3O4 was facilitated by reduced rhenium by a H2-spillover mechanism. In situ XRD results showed the presence of both, Co-hcp and Co-fcc phases in the reduced catalyst at 400 C. However, the Co-hcp phase was more abundant, which is thought to be the more active phase as compared to the Co-fcc phase for CO hydrogenation. CO hydrogenation at 270 C and 5 bar pressure produces no detectable change in the phases during the time of experiment. In situ XANES results showed a decrease in the metallic cobalt in the presence of H2/CO, which can be attributed due to oxidation of the catalyst by reaction under these conditions.

  19. Synthesis, structural and vibrational investigation on 2-phenyl-N-(pyrazin-2-yl)acetamide combining XRD diffraction, FT-IR and NMR spectroscopies with DFT calculations.

    PubMed

    Lukose, Jilu; Yohannan Panicker, C; Nayak, Prakash S; Narayana, B; Sarojini, B K; Van Alsenoy, C; Al-Saadi, Abdulaziz A

    2015-01-25

    The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 2-phenyl-N-(pyrazin-2-yl)acetamide have been investigated experimentally and theoretically using Gaussian09 software package. The title compound was optimized by using the HF/6-31G(6D,7F) and B3LYP/6-31G(6D,7F) calculations. The geometrical parameters are in agreement with the XRD data. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. Gauge-including atomic orbital (1)H-NMR chemical shifts calculations were carried out and compared with experimental data. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. Molecular electrostatic potential was performed by the DFT method. First hyperpolarizability is calculated in order to find its role in non linear optics. From the XRD data, in the crystal, molecules are held together by strong C-H?O and N-H?O intermolecular interactions. PMID:25124846

  20. Modifying the growth morphology of aluminum crystals by magnetic mirror in a thermal plasma reactor

    NASA Astrophysics Data System (ADS)

    Torrente, G.; Puerta, J.; Labrador, N.; Molina, A.

    2013-11-01

    Effect of magnetic fields on growth morphology of aluminum crystals was studied in a fluidized bed thermal plasma reactor assisted by magnetic mirrors. Aluminum crystals were precipitated in the reactor using aluminum powder or aluminum-graphite mixture as precursors. The absent of magnetic field was also studied for comparison. Products were characterized by scanning electron microscopy (SEM) and X-ray Diffraction (XRD). Results indicated that, regardless the precursor used, it was observed the presence of aluminum nanowires when the external magnetic mirror was applied, suggesting that magnetic fields are able to modify growth morphology at nanoscale.

  1. Observation of dimension dependent magnetic ordering in bismuth ferrite particulate and fiber nanostructures

    NASA Astrophysics Data System (ADS)

    Sakar, M.; Bharathkumar, S.; Saravanan, P.; Balakumar, S.

    2015-06-01

    Nanoparticles and nanofibers of bismuth ferrite were fabricated by sol-gel and electrospinning methods respectively. The structural and morphological analysis was carried out by XRD and FESEM techniques respectively. The magnetic measurements were carried out by SQUID magnetometer. The BFO nanofibers showed an enhanced magnetic property compared to nanoparticles. The observed magnetic properties were found to be associated with their magnetic ordering in the system where the antiferromagnetic/ferromagnetic core/shell like nature and `canted' spin structure ordering was found to be the magnetic origin in the particulate and fiber nanostructures respectively.

  2. Transmission electron microscopy and ab initio calculations to relate interfacial intermixing and the magnetism of core/shell nanoparticles

    SciTech Connect

    Chi, C.-C.; Hsiao, C.-H.; Ouyang, Chuenhou; Skoropata, E.; Lierop, J. van

    2015-05-07

    Significant efforts towards understanding bi-magnetic core-shell nanoparticles are underway currently as they provide a pathway towards properties unavailable with single-phased systems. Recently, we have demonstrated that the magnetism of ?-Fe2O3/CoO core-shell nanoparticles, in particular, at high temperatures, originates essentially from an interfacial doped iron-oxide layer that is formed by the migration of Co{sup 2+} from the CoO shell into the surface layers of the ?-Fe2O3 core [Skoropata et al., Phys. Rev. B 89, 024410 (2014)]. To examine directly the nature of the intermixed layer, we have used high-resolution transmission electron microscopy (HRTEM) and first-principles calculations to examine the impact of the core-shell intermixing at the atomic level. By analyzing the HRTEM images and energy dispersive spectra, the level and nature of intermixing was confirmed, mainly as doping of Co into the octahedral site vacancies of ?-Fe2O3. The average Co doping depths for different processing temperatures (150?°C and 235?°C) were 0.56?nm and 0.78?nm (determined to within 5% through simulation), respectively, establishing that the amount of core-shell intermixing can be altered purposefully with an appropriate change in synthesis conditions. Through first-principles calculations, we find that the intermixing phase of ?-Fe2O3 with Co doping is ferromagnetic, with even higher magnetization as compared to that of pure ?-Fe2O3. In addition, we show that Co doping into different octahedral sites can cause different magnetizations. This was reflected in a change in overall nanoparticle magnetization, where we observed a 25% reduction in magnetization for the 235?°C versus the 150?°C sample, despite a thicker intermixed layer.

  3. Magnetite/CdTe magnetic-fluorescent composite nanosystem for magnetic separation and bio-imaging

    NASA Astrophysics Data System (ADS)

    Kale, Anup; Kale, Sonia; Yadav, Prasad; Gholap, Haribhau; Pasricha, Renu; Jog, J. P.; Lefez, Benoit; Hannoyer, Béatrice; Shastry, Padma; Ogale, Satishchandra

    2011-06-01

    A new synthesis protocol is described to obtain a CdTe decorated magnetite bifunctional nanosystem via dodecylamine (DDA) as cross linker. High resolution transmission electron microscopy (HRTEM), energy-dispersive x-ray spectroscopy (EDAX), vibrating sample magnetometry (VSM), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS) and fluorescence microscopy are used to characterize the constitution, size, composition and physical properties of these superparamagnetic-fluorescent nanoparticles. These CdTe decorated magnetite nanoparticles were then functionalized with anti-epidermal growth factor receptor (EGFR) antibody to specifically target cells expressing this receptor. The EGFR is a transmembrane glycoprotein and is expressed on tumor cells from different tissue origins including human leukemic cell line Molt-4 cells. The magnetite-CdTe composite nanosystem is shown to perform excellently for specific selection, magnetic separation and fluorescent detection of EGFR positive Molt-4 cells from a mixed population. Flow cytometry and confocal laser scanning microscopy results show that this composite nanosystem has great potential in antibody functionalized magnetic separation and imaging of cells using cell surface receptor antibody.

  4. Magnetic Spinner

    ERIC Educational Resources Information Center

    Ouseph, P. J.

    2006-01-01

    A science toy sometimes called the "magnetic spinner" is an interesting class demonstration to illustrate the principles of magnetic levitation. It can also be used to demonstrate Faraday's law and a horizontally suspended physical pendulum. The levitated part contains two circular magnets encased in a plastic housing. Each magnet stays…

  5. Structural and magnetic studies in ferrihydrite nanoparticles formed within organic-inorganic hybrid matrices

    SciTech Connect

    Silva, N. J. O.; Amaral, V. S.; Carlos, L. D.; Rodriguez-Gonzalez, B.; Liz-Marzan, L. M.; Millan, A.; Palacio, F.; Zea Bermudez, V. de

    2006-09-01

    We report detailed transmission electron microscopy, high resolution transmission electron microscopy (HRTEM), and scanning transmission electron microscopy/energy dispersive x-ray spectroscopy (STEM/EDS) studies on ferrihydrite nanoparticles in an organic-inorganic matrix. The Fourier transform of HRTEM images indicates the existence of six-line ferrihydrite. Combined STEM and EDS studies give further confirmation of the presence of iron in the observed particles and its absence in the matrix. The derived mean particle size and size distribution is 4.7{+-}0.2 nm with a lognormal deviation of s=0.4{+-}0.1. These values were used for analysis of magnetic measurements, yielding the determination of the anisotropy constant K{sub eff}=4x10{sup 5} erg/cm{sup 3} and the power relation between the number of iron ions per particle and the number of uncompensated ones p{approx_equal}1/3. This value indicates that the uncompensated spins are mainly randomly distributed at the surface. According to this model, a shell thickness of about one ferrihydrite unit cell is estimated.

  6. Seismicity triggered by the olivine-spinel transition: new insights from combined XRD and acoustic emission monitoring during deformation experiments in Mg2GeO4

    NASA Astrophysics Data System (ADS)

    Schubnel, A.; Hilairet, N.; Brunet, F.; Gasc, J.; Cordier, P.; Wang, Y.; Green, H. W.

    2012-04-01

    Polycrystalline Mg2GeO4-olivine has been deformed (strain rates from 2.10-4/s to 10-5/s) in the deformation-DIA in 13-BM-D at GSECARS (Advanced Photon Source) at ca. 2 GPa confining pressure for temperatures between 973 and 1573 K (i.e., in the Mg2GeO4-ringwoodite field). Stress, advancement of transformation, and strain were measured in-situ using X-ray diffraction (XRD) and imaging, and acoustic emissions (AE) were recorded simultaneously. When differential stress is applied (ca. 1- to 2 GPa) and temperature is increased, the very beginning of the transformation to the ringwoodite structure (as evidenced by in situ XRD) is accompanied by AE bursts which locate within the sample. At high strain rates (>10-4/s) and low temperatures (800-900 degrees C), the number of AEs is comparable, if not larger, to that observed during the cold compression of quartz grains. The largest events always occur at a temperature slightly below that of appearance of the ringwoodite-structure phase on the XRD images patterns. This suggests that AEs are generated while the transition is still nucleation controlled (pseudo-martensitic stage). During stress-relaxation periods, the rate of AE triggering decreases, but does not completely vanish. Importantly, we still observed very large AEs at strain rates as low as approx. 10-5/ s, while at these early stages of the transformation, the samples did not show any macroscopic rheological weakening. Focal mechanism analysis of the largest AEs showed that they are all of shear type, some being even pure double couple. They radiate about the same amount of energy as typically recorded during fast crack propagation in amorphous glass material. Microstructural analysis (SEM, EBSD and TEM) highlights the presence of thin transformation bands, with plausible evidence of shear (grain distortion and grain size reduction). These bands are made of incoherent spinel and olivine nano-grains which run across germanium-olivine grain boundaries. These bands are all oriented near perpendicular to the principal compressive stress. In samples for which no AEs were recorded (hydrostatic conditions and higher temperatures and reaction progress), microstructure is different with incoherent grain growth at GB (hydrostatic conditions) and spinel-lamellae within a single germanium olivine crystal (fast reaction rate under deviatoric stress). Our observations point out that under high deviatoric stress, the olivine - spinel transition is a source of mechanical instability, which produces nano-seismicity. This may have important consequences for the understanding of deep-focus earthquakes occurring in cold and metastable olivine within the transition zone.

  7. Seismicity triggered by the olivine-spinel transition: new insights from combined XRD and acoustic emission monitoring during deformation experiments in Mg2GeO4

    NASA Astrophysics Data System (ADS)

    Schubnel, A. J.; Hilairet, N.; Brunet, F.; Héripré, E.; Cordier, P.; Wang, Y.

    2011-12-01

    Polycrystalline Mg2GeO4-olivine has been deformed (strain rates from 2.10-4/s to 10-5/s) in the deformation-DIA in 13-BM-D at GSECARS (Advanced Photon Source) at ca. 2 GPa confining pressure for temperatures between 973 and 1573 K (i.e., in the Mg2GeO4-ringwoodite field). Stress, advancement of transformation, and strain were measured in-situ using X-ray diffraction (XRD) and imaging, and acoustic emissions (AE) were recorded simultaneously. When differential stress is applied (ca. 1- to 2 GPa) and temperature is increased, the very beginning of the transformation to the ringwoodite structure (as evidenced by in situ XRD) is accompanied by AE bursts which locate within the sample. At high strain rates (>10-4/s) and low temperatures (800-900 degrees C), the number of AEs is comparable, if not larger, to that observed during the cold compression of quartz grains. The largest events always occur at a temperature slightly below that of appearance of the ringwoodite-structure phase on the XRD images patterns. This suggests that AEs are generated while the transition is still nucleation controlled (pseudo-martensitic stage). During stress-relaxation periods, the rate of AE triggering decreases, but does not completely vanish. Importantly, we still observed very large AEs at strain rates as low as approx. 10-5/ s, while at these early stages of the transformation, the samples did not show any macroscopic rheological weakening. Focal mechanism analysis of the largest AEs showed that they are all of shear type, some being even pure double couple. They radiate about the same amount of energy as typically recorded during fast crack propagation in amorphous glass material. Microstructural analysis (SEM, EBSD and TEM) highlights the presence of thin transformation bands, with plausible evidence of shear (grain distortion and grain size reduction). These bands are made of incoherent spinel and olivine nano-grains which run across germanium-olivine grain boundaries. These bands are all oriented near perpendicular to the principal compressive stress. In samples for which no AEs were recorded (hydrostatic conditions and higher temperatures and reaction progress), microstructure is different with incoherent grain growth at GB (hydrostatic conditions) and spinel-lamellae within a single germanium olivine crystal (fast reaction rate under deviatoric stress). Our observations point out that under high deviatoric stress, the olivine - spinel transition is a source of mechanical instability, which produces nano-seismicity. This may have important consequences for the understanding of deep-focus earthquakes occurring in cold and metastable olivine within the transition zone.

  8. Structural and magnetic properties of nano-crystalline Ni-Zn ferrites synthesized using egg-white precursor

    NASA Astrophysics Data System (ADS)

    Gabal, M. A.; El-Shishtawy, Reda M.; Al Angari, Y. M.

    2012-07-01

    Nano-crystalline nickel-zinc ferrites of different compositions; Ni1-xZnxFe2O4 (x=0.0-1.0) were prepared by a precursor method involving egg-white and metal nitrates. An appropriate mechanism for the egg-white-metal complexation was suggested. Differential thermal analysis-thermogravimetry, X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer and AC-magnetic susceptibility measurements were carried out to investigate chemical, structural and magnetic aspects of Ni-Zn ferrites. XRD confirmed the formation of spinel cubic structure. The average crystallite size was calculated using line broadening in XRD patterns. Structural parameters like lattice constant, X-ray density, bond lengths and inter-cationic distance were determined from XRD data. TEM showed agglomerated particles with average size agreed well with that estimated using XRD. FT-IR spectra confirm the formation of spinel structure and further lends support to the proposed cation distribution. Zn-content was found to have a significant influence on the magnetic properties of the system. The changes in the magnetic properties can be attributed to the influence of the cationic stoichiometry and their occupancy in the specific sites.

  9. Structural, vibrational and magnetic properties of Ni1-xCoxFe2O4 ferrites

    NASA Astrophysics Data System (ADS)

    Nandan, Brajesh; Bhatnagar, M. C.

    2015-08-01

    The ferrite with chemical formula Ni1-xCoxFe2O4 (x= 0.00, 0.50, 1.00) were prepared using sol-gel method. X-ray diffraction (XRD), Raman spectroscopy and physical property measurement system (PPMS) were used to characterize the structural, vibrational and magnetic properties. XRD pattern confirmed single crystalline spinel structure of Nickel ferrite with Co substitution. Lattice parameter variation confirms the substitution of Co2+ ions at the place of Ni2+ into the nickel ferrite. Raman scattering at room temperature is used to study the redistribution of Ni and Co cations between tetrahedral (A) and octahedral (B) sites. A shift is observed in Co substitute nickel ferrite in both XRD and Raman studies. M-H hysteresis is carried out at room temperature. Saturation magnetization of the samples is increased with the Co2+ ions substitution.

  10. Magnetic properties of Acidithiobacillus ferrooxidans.

    PubMed

    Yan, Lei; Zhang, Shuang; Chen, Peng; Wang, Weidong; Wang, Yanjie; Li, Hongyu

    2013-10-01

    Understanding the magnetic properties of magnetotactic bacteria (MTBs) is of great interest in fields of life sciences, geosciences, biomineralization, biomagnetism, and planetary sciences. Acidithiobacillus ferrooxidans (At. ferrooxidans), obtaining energy through the oxidation of ferrous iron and various reduced inorganic sulfur compounds, can synthesize intracellular magnetite magnetosomes. However, the magnetic properties of such microorganism remain unknown. Here we used transmission electronmicroscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) assay, vibrating sample magnetometer (VSM), magneto-thermogravimetric analysis (MTGA), and low temperature magnetometry to comprehensively investigate the magnetic characteristics of At. ferrooxidans. Results revealed that each cell contained only 1 to 3 magnetite magnetosomes, which were arranged irregularly. The magnetosomes were generally in a stable single-domain (SD) state, but superparamagnetic (SP) magnetite particles were also found. The calcined bacteria exhibited a ferromagnetic behavior with a Curie Temperature of 454 °C and a coercivity of 16.36 mT. Additionally, the low delta ratio (?FC/?ZFC=1.27) indicated that there were no intact magnetosome chains in At. ferrooxidans. Our results provided the new insights on the biomineralization of bacterial magnetosomes and magnetic properties of At. ferrooxidans. PMID:23910310

  11. Structure and occurrences of ? green rust ? related new minerals of the ? fougérite ? group, trébeurdenite and mössbauerite, belonging to the ? hydrotalcite ? supergroup; how Mössbauer spectroscopy helps XRD.

    NASA Astrophysics Data System (ADS)

    Génin, J.-M. R.; Christy, A.; Kuzmann, E.; Mills, S.; Ruby, C.

    2014-04-01

    Mössbauer spectroscopy yields decisive information for interpreting x-ray diffraction (XRD) patterns in the case of `green rusts" with intercalated CO anions, i.e. the chemical analogs of the three minerals that constitute within the ? hydrotalcite ? supergroup comprising 44 minerals the " fougèrite" group where the structure stays globally unchanged. The only difference comes from the deprotonation of OH- ions at the apices of the octahedrons occupied by the Fe cations so that Fe I I ions become Fe I I I . Low angle x-ray diffraction using synchrotron radiation displays the presence of many polytypes which reflects the stacking of brucite like layers and anion interlayers so that a 2D long range order of anions stays unchanged from fougèrite to mössbauerite.

  12. A new approach in quantitative in-situ XRD of cement pastes: Correlation of heat flow curves with early hydration reactions

    SciTech Connect

    Hesse, Christoph; Goetz-Neunhoeffer, Friedlinde; Neubauer, Juergen

    2011-01-15

    XRD measurements of the hydration of synthetical cement (SyCem) were used to calculate the resulting heat flow from changes in the phase content. Calculations were performed by application of thermodynamic data. The comparison with data recorded from heat flow calorimetry was in good agreement with the calculated heat flow. The initial maximum of heat flow mainly is caused by the aluminate reaction. During the entire main period the silicate reaction dominates hydration with a high and long first maximum of heat flow. The second but less intense heat flow maximum - only visible as a shoulder in most of the technical cements - can be attributed to an acceleration of the aluminate reaction with the enhanced dissolution of C{sub 3}A and the final formation of ettringite. Moreover, the investigation showed that the dissolution process of C{sub 3}A is directly controlled by the availability of the calcium sulfate phases.

  13. [X-ray diffraction (XRD) and near infrared spectrum (NIR) analysis of the soil overlying the Bairendaba deposit of the Inner Mongolia Grassland].

    PubMed

    Luo, Song-ying; Cao, Jian-jin; Wu, Zheng-quan

    2014-08-01

    The soil samples uniformly overlying the Bairendaba deposit of the Inner Mongolia grassland were collected, and ana- lyzed with X-ray diffraction (XRD) and near infrared spectrum (NIR), for exploring the origins of the soil from the, grassland mining area and the relationship with the underground rock. The results show that the samp]s consist of quartz, graphite, carbonate, hornblende, mica, chlorite, montmorillonite, illite, berlinite, diaspore, azurite, hen tite, etc. These indicate that the soil samples were not only from the weathering products of the surface rock, but also from the underground rock mass and the alteration of the wall rock. The azurite and the hematite contained in the soil, mainly coming from the oxidation zone of the orebodies, can be used as the prospecting marks. The alteration mineral assemblage is mainly chlorite-illite-montmorillonite and it experienced the alteration process of potassic alteration-->silicification-->carbonatization-->silk greisenization-->clayization. Also, the wall rock alteration and the physical weathering processes can be accurately restored by analyzing the combination of the alteration minerals, which can provide important reference information for the deep ore prospecting and the ore deposit genesis study, improving the rate of the prospecting. The XRD and NIR with the characteristics of the economy and quickness can be used for the identification of mineral composition of soil, and in the study of mineral and mineral deposits. Especially, NIR has its unique superiority, that is, its sample request is low, and it can analyze a batch of samples quickly. With the development of INR, it will be more and more widely applied in geological field, and can play an important role in the ore exploration. PMID:25508754

  14. [X-ray diffraction (XRD) and near infrared spectrum (NIR) analysis of the soil overlying the Bairendaba deposit of the Inner Mongolia Grassland].

    PubMed

    Luo, Song-ying; Cao, Jian-jin; Wu, Zheng-quan

    2014-08-01

    The soil samples uniformly overlying the Bairendaba deposit of the Inner Mongolia grassland were collected, and ana- lyzed with X-ray diffraction (XRD) and near infrared spectrum (NIR), for exploring the origins of the soil from the, grassland mining area and the relationship with the underground rock. The results show that the samp]s consist of quartz, graphite, carbonate, hornblende, mica, chlorite, montmorillonite, illite, berlinite, diaspore, azurite, hen tite, etc. These indicate that the soil samples were not only from the weathering products of the surface rock, but also from the underground rock mass and the alteration of the wall rock. The azurite and the hematite contained in the soil, mainly coming from the oxidation zone of the orebodies, can be used as the prospecting marks. The alteration mineral assemblage is mainly chlorite-illite-montmorillonite and it experienced the alteration process of potassic alteration-->silicification-->carbonatization-->silk greisenization-->clayization. Also, the wall rock alteration and the physical weathering processes can be accurately restored by analyzing the combination of the alteration minerals, which can provide important reference information for the deep ore prospecting and the ore deposit genesis study, improving the rate of the prospecting. The XRD and NIR with the characteristics of the economy and quickness can be used for the identification of mineral composition of soil, and in the study of mineral and mineral deposits. Especially, NIR has its unique superiority, that is, its sample request is low, and it can analyze a batch of samples quickly. With the development of INR, it will be more and more widely applied in geological field, and can play an important role in the ore exploration. PMID:25474975

  15. Ion-pairing in aqueous CaCl2 and RbBr solutions: simultaneous structural refinement of XAFS and XRD data

    SciTech Connect

    Pham, Thai V.; Fulton, John L.

    2013-01-28

    We present a new methodology involving the simultaneous refinement of both x-ray absorption and x-ray diffraction spectra (X-ray Absorption/Diffraction Structural Refinement,XADSR), to study hydration and ion pair structure of CaCl2 and RbBr salts in concentrated aqueous solutions. The XADSR analysis includes the XAFS spectra analysis of both the cation and anion as a probe of their short-range structure with an XRD spectral analysis as a probe of the global structural. Together they deliver a comprehensive picture of the cation and anion hydration, the contact ion pair (CIP) structure and the solvent-separated ion pair (SSIP) structure. XADSR analysis of 6.0 m aqueous CaCl2 reveals that there are an insignificant number of Ca2+-Cl- CIP’s, but there are approximately 3.4 SSIP’s separated by about 4.99 Å. In contrast XADSR analysis of aqueous RbBr yields about 0.7 pair CIP at a bond length 3.51 Å. The present work demonstrates a new approach for a direct co-refinement of XRD and XAFS spectra in a simple and reliable fashion, opening new opportunities for analysis in various disordered and crystalline systems. This work was supported by the U.S. Department of Energy (DOE), Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Pacific Northwest National Laboratory (PNNL) is operated for the U.S. Department of Energy by Battelle.

  16. Magnetic Protostars

    NASA Astrophysics Data System (ADS)

    Glagolevskij, Yu. V.

    2015-09-01

    A possible variant of the evolution of magnetic protostars "before the Hayashi phase" is discussed. Arguments are given in support of the following major properties of magnetic stars: (1) global magnetic dipole fields with predominant orientation of the magnetic lines of force in the plane of the equator of revolution; (2) slow rotation; (3) complex, two and three dipole structures of the magnetic field in a large part of the stars; (4) partition of stars into magnetic and normal in a proportion of 1:10 occurs during the period when the protostellar clouds undergo gravitational collapse "before the Hayashi phase."

  17. Structural and magnetic properties of chromium doped zinc ferrite

    SciTech Connect

    Sebastian, Rintu Mary; Thankachan, Smitha; Xavier, Sheena; Mohammed, E. M.; Joseph, Shaji

    2014-01-28

    Zinc chromium ferrites with chemical formula ZnCr{sub x}Fe{sub 2?x}O{sub 4} (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) were prepared by Sol - Gel technique. The structural as well as magnetic properties of the synthesized samples have been studied and reported here. The structural characterizations of the samples were analyzed by using X – Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), and Transmission Electron Microscope (TEM). The single phase spinel cubic structure of all the prepared samples was tested by XRD and FTIR. The particle size was observed to decrease from 18.636 nm to 6.125 nm by chromium doping and induced a tensile strain in all the zinc chromium mixed ferrites. The magnetic properties of few samples (x = 0.0, 0.4, 1.0) were investigated using Vibrating Sample Magnetometer (VSM)

  18. Structural Investigation of MFe2O4 (M ) Fe, Co) Magnetic Fluids Guilherme V. M. Jacintho,

    E-print Network

    Brolo, Alexandre G.

    -enhanced Raman scattering (SERS). XRD and TEM analysis have shown that the magnetic nanoparticles (nonmodified in the Raman spectra and vice versa. SERS measurements of a CoFe2O4 thin film on a SERS-active gold electrode

  19. Mechanical synthesis of nanostructured nickel-zinc ferrite and investigation of magnetic properties

    NASA Astrophysics Data System (ADS)

    Radhika, K.; Yasin, Sk. Mohammad; Kumar, N. Harish

    2012-06-01

    Nanocrystalline Ni-Zn ferrite was synthesized at room temperature by high energy ball milling. Crystallographic phases appearing during ball milling & crystallite sizes were determined from X-ray diffraction (XRD) analysis. The magnetic response of the powder samples were investigated using vibrating sample magnetometer (VSM) which showed 30hr milled un annealed sample to be superparamagnetic.

  20. Study of hard-soft magnetic ferrite films prepared by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Satalkar, M.; Kane, S. N.; Ghosh, A.; Raghuvanshi, S.; Tapkir, P.; Ghodke, N.; Phase, D. M.; Chaudhary, R. J.; Pasko, A.; LoBue, M.; Mazaleyrat, F.

    2014-09-01

    Soft magnetic Mg0.1Ni0.3Zn0.6Fe2O4 and hard magnetic BaFe12O19 bulk nanocrystalline ferrites were synthesized using the sol-gel auto-combustion method, and were used as targets to deposit soft-hard thin films by the pulsed laser deposition (PLD) method. Various soft-hard thin films with different preparation conditions were deposited on Si (100) substrate, which can be effectively utilized to get better magnetic properties. The prepared films were characterized by the X-ray diffraction (XRD), atomic force microscopy (AFM) and magnetic measurements. XRD confirms the presence of soft and hard phases in the thin films. Coercivity of the prepared films ranges from 1.67 to 2.66 kA/m. AFM images show clustering of grains at the film surface with a characteristic columnar growth.

  1. Fabrication, characterization, and magnetic behavior of porous ZnFe2O4 hollow microspheres

    NASA Astrophysics Data System (ADS)

    Matli, Penchal Reddy; Zhou, Xiaobing; Shiyu, Du; Huang, Qing

    2015-12-01

    Porous ZnFe2O4 hollow microspheres with a diameter of about 100-210 nm were successfully prepared by simple template-free hydrothermal route in ethylene glycol (EG) solution. The formation mechanism and properties have been also demonstrated. The structural, morphological, and magnetic properties of ZnFe2O4 hollow microspheres were investigated by means of X-ray powder diffraction (XRD), field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and physical properties measurements system. The surface area was determined using the BET method. XRD and IR analyses confirm the cubic spinel phase of ZnFe2O4 hollow microspheres. Every magnetic microsphere is made up of many ultrafine ZnFe2O4 nanoparticles with porous structure. The as-prepared porous magnetic hollow spheres have higher surface area and excellent magnetic properties at room temperature.

  2. Planetary magnetism

    NASA Technical Reports Server (NTRS)

    Russell, C. T.

    1981-01-01

    A synoptic view of early and recent data on the planetary magnetism of Mercury, Venus, the moon, Mars, Jupiter, and Saturn is presented. The data on Mercury from Mariner 10 are synthesized with various other sources, while data for Venus obtained from 120 orbits of Pioneer Venus give the upper limit of the magnetic dipole. Explorer 35 Lunar Orbiter data provided the first evidence of lunar magnetization, but it was the Apollo subsatellite data that measured accurately the magnetic dipole of the moon. A complete magnetic survey of Mars is still needed, and only some preliminary data are given on the magnetic dipole of the planet. Figures on the magnetic dipoles of Jupiter and Saturn are also suggested. It is concluded that if the magnetic field data are to be used to infer the interior properties of the planets, good measures of the multiple harmonics in the field are needed, which may be obtained only through low altitude polar orbits.

  3. Magnetic Fields

    E-print Network

    Schöller, Markus

    2015-01-01

    In this chapter, we give a brief introduction into the use of the Zeeman effect in astronomy and the general detection of magnetic fields in stars, concentrating on the use of FORS2 for longitudinal magnetic field measurements.

  4. Superconducting magnets

    SciTech Connect

    Not Available

    1994-08-01

    This report discusses the following topics on superconducting magnets: D19B and -C: The next steps for a record-setting magnet; D20: The push beyond 10 T: Beyond D20: Speculations on the 16-T regime; other advanced magnets for accelerators; spinoff applications; APC materials development; cable and cabling-machine development; and high-{Tc} superconductor at low temperature.

  5. Magnetization processes in hybrid magnets

    NASA Astrophysics Data System (ADS)

    Emura, M.; Neiva, A. C.; Missell, F. P.; Babcock, K. L.; Ormerod, J.; Constantinides, S.

    1998-06-01

    Injection-molded, oriented hybrid magnets consisting of mixtures of BaO?6Fe2O3 and MQP-Q (exchange-coupled Nd2Fe14B+?-Fe) are compared to bonded magnets made only from ferrite or MQP-Q. The magnetic fractions of the hybrid magnets consist of 80, 60, or 40 wt % ferrite blended with 20, 40, or 60 wt % MQP-Q. The microstructure was investigated by x-ray diffraction, scanning electron microscopy, atomic force microscopy, and magnetic force microscopy. Atomic and magnetic force microscopy images indicated differences between the physical and magnetic microstructures. Magnetic interactions were studied via isothermal remanence (IRM) and dc-demagnetization (DCD) remanence curves and Henkel plots. In contrast to what is observed in exchange spring magnets, the IRM and DCD susceptibilities of all magnets present peaks of nearly the same width, centered at roughly the same value of the magnetic field, consistent with weak dipolar interactions between magnetic particles. The IRM susceptibilities show structure associated with magnetic inhomogenieties in the samples.

  6. Seismicity triggered by the olivine-spinel transition: New insights from combined XRD and acoustic emission monitoring during deformation experiments in Mg2GeO4

    NASA Astrophysics Data System (ADS)

    Schubnel, A. J.; Hilairet, N.; Gasc, J.; Héripré, E.; Brunet, F.; Wang, Y.

    2010-12-01

    Polycrystalline Mg2GeO4-olivine has been deformed (strain rates from 2.10-4/s to 10-5/s) in the deformation-DIA in 13-BM-D at GSECARS (Advanced Photon Source) at ca. 2 GPa confining pressure for temperatures between 973 and 1573 K (i.e., in the Mg2GeO4-ringwoodite field). Stress, advancement of transformation, and strain were measured in-situ using X-ray diffraction (XRD) and imaging, and acoustic emissions (AE) full waveforms were recorded simultaneously. When differential stress is applied (ca. 1- to 2 GPa) and temperature is increased, the very beginning of the transformation to the ringwoodite structure (as evidenced by in situ XRD) is accompanied by AE bursts which locate within the sample. At high strain rates (>10-4/s) and low temperatures (800-900 degrees C), the number of AEs is comparable, if not larger, to that observed during the cold compression of quartz grains. The largest events always occur at a temperature slightly below that of appearance of the ringwoodite-structure phase on the XRD images patterns. This suggests that AEs are generated while the transition is still nucleation controlled (pseudo-martensitic stage). During stress-relaxation periods, the rate of AE triggering decreases, but does not completely vanish. The AE production rate increases again as soon as deformation is started again. Importantly, we still observed very large AEs at strain rates as low as approx. 10-5/ s. At these early stages of the transformation, the samples did not show any macroscopic rheological weakening. Focal mechanism analysis of the largest AEs showed that they are all of shear type, some being even pure double couple. They radiate about the same amount of energy as typically recorded during fast crack propagation in amorphous glass material. This suggests that they cannot only originate from the martensitic nucleation of oriented spinel-lamellae within a single germanium olivine crystal. Preliminary microstructural analysis (SEM and EBSD) highlights the presence of thin transformation bands made of incoherent spinel micro-grains which, possibly, run across germanium-olivine grain boundaries. These bands are all oriented near perpendicular to the principal compressive stress. Our observations point out that under high deviatoric stress, the olivine - spinel transition is a source of instability which produces micro-sismicity (no AEs were recorded in a similar experiment performed hydrostatically). These instabilities might eventually be precursor to brittle fracturing as observed by Green and Burnley (1989) in their deformation experiments on very similar samples. Both types of study emphasize the potential of phase transitions (with negative volume variations) in triggering brittle failure. Obviously, this has important consequences for the understanding of deep-focus earthquakes occurring in cold and metastable olivine within the transition zone.

  7. X-radiography, XRD and Ultrasonic Data Transfer Function Technique - Simultaneous Measurements Under Simulated Mantle Conditions in a Multi-Anvil Device

    NASA Astrophysics Data System (ADS)

    Mueller, H. J.; Schilling, F. R.; Lathe, C.

    2004-05-01

    The interpretation of seismic data from the Earth's deep interior requires measurements of the physical properties of Earth materials under experimental simulated mantle conditions. Elastic wave velocity measurement is an important tool for the determination of the elastic properties. Ultrasonic interferometry allows the highly precise travel time measurement at a sample enclosed in a high-pressure multi-anvil device. But the calculation of wave velocities requires the exact sample length under in situ conditions. There are two options - scanning the interfaces of the sample by XRD (Mueller et al., 2003) and X-radiography (Li et al., 2001). The multi-anvil apparatus MAX80 is equipped for both methods. Only the X-radiography is fast enough for transient measurements. Contrary to XRD measurements, imaging the sample by X-rays requires a beam diameter larger than the sample length. Therefore the fixed primary slits of Max80 were exchanged by 4-blade high precision slits of Advanced Design Consulting, Inc. A Ce-YAG-crystal converts the X-ray image to an optical one, redirected by a mirror and captured by a CCD-camera. To derive the sample length, the different brightness of sample, buffer rod and reflector at the electronic image is evaluated. Classical ultrasonic interferometry is very time consuming, because the ultrasonic waves of the frequency range under study are generated and detected one after another with a given step rate. A 60 MHz frequency sweep with 100 kHz steps lasts for more than 30 minutes. This is a serious limitation for all transient measurements, but also limits the data collection at elevated temperatures to prevent the pressure transmitting boron epoxy cubes and the anvils from overheating. The ultrasonic transfer function technique (UTF), first described by Li et al. (2002), generates all the frequencies simultaneously. Related to the results and experiences of Li the UTF-technique was developed independently at GFZ. This version allows to consider the characteristics of the specific transducer-glue-anvil combination (Mueller et al., 2003). To collect the data for the following calculation of Vp and Vs requires just few seconds. The excitation function, applied to the transducer by an arbitrary waveform generator, is the result of the summation of all sinusoidal waves inside the frequency range. The response of the system - transducer - anvil - buffer rod - sample - reflector - for each of the frequencies can be reproduced by convoluting the resulting transfer function with these monochromatic waves step by step. Some recent results on the non-quenchable high-P - low-P clinoenstatite transition and to the quartz-coesite transition will be given to discuss the different interferometric techniques, including the XRD-data and X-radiography results, necessary to detect the phase transitions under in situ conditions and to measure the sample deformation. Li, B.; Vaughan, M.T.; Kung, J.; Weidner, D.J., NSLS Activity Report 2001, 2-103-106, (2001). Li, B.; Chen, K.; Kung, J.; Liebermann, R.C.; Weidner, D.J., J. Phys.: Condens. Matter 14, 11337-11342, (2002). Mueller, H.J.; Schilling, F.R.; Lauterjung, J.; Lathe, C., Eur. J. Mineral., 15, 865-873, (2003). Mueller, H.J.; Wunder, B.; Lathe, C.; Schilling, F.R.; Eur. J. Mineral., submitted, (2004).

  8. Probing magnetic properties of ferrofluids using temperature dependent magnetic hyperthermia studies

    NASA Astrophysics Data System (ADS)

    Nemala, Humeshkar; Thakur, Jagdish; Naik, Vaman; Naik, Ratna

    2014-03-01

    Tuning the properties of magnetic nanoparticles is essential for biomedical and technological applications. An important phenomenon displayed by these nanoparticles is the generation of heat in the presence of an external oscillating magnetic field and is known as magnetic hyperthermia (MHT). The heat dissipation by the magnetic nanoparticles occurs via Neel relaxation (the flip of the internal magnetic moment of the nanoparticles) and Brownian relaxation (the physical rotation of the nanoparticles in the suspended media). Dextran coated iron oxide (Fe3O4) nanoparticles were synthesized using the co-precipitation method and characterized using XRD, TEM and DC magnetometry measurements. Roughly spherical in shape the particles have an average size of 13nm and a saturation magnetization of 65 emu/g. The MHT properties of these nanoparticles suspended in a weakly basic solution (ferrofluid) have been investigated as a function of the frequency and amplitude of magnetic field by incorporating a complete thermodynamical analysis of the experimental set-up. The heat generation is quantified using the specific power loss (SPL) and compared with the predictions of linear response theory. This analysis sheds light on important physical and magnetic properties of the nanoparticles.

  9. Electroplating hard magnetic SmCo for magnetic microactuator applications

    NASA Astrophysics Data System (ADS)

    Chen, Jue; Rissing, Lutz

    2011-04-01

    Patterned SmCo thin films were electroplated from an aqueous solute containing glycine by using dc and pulse dc current on the beaker level. Micromolds prepared by photolithography allow an accurate pattern transfer for patterned deposition of the material. A flux guide of a magnetic microactuator was chosen as a pattern, and Al2O3 was used as the substrate. Au and Cr were investigated as seed layer materials. The content of Sm in the SmCo films is strongly dependent on the applied cathodic current density. A relative Sm content of up to 13.8 at. % could be determined by energy dispersive x-ray (EDX) spectroscopy. The SmCo thin films were annealed at 560 °C in a vacuum oven. Vibrating sample magnetometer (VSM) measurements were applied to characterize the magnetic properties. This film features hard magnetic properties with an intrinsic coercivity Hci of up to 44 kA/m. Electron probe microanalysis (EPMA) measurements showed that up to 40 at. % of O may be integrated in these films. The phases in the deposited films were determined by applying X-ray diffraction (XRD) measurements. These films consist of a mixture of SmCo alloy, Sm oxide, and Co.

  10. Electroplating hard magnetic SmCo for magnetic microactuator applications

    SciTech Connect

    Chen Jue; Rissing, Lutz

    2011-04-01

    Patterned SmCo thin films were electroplated from an aqueous solute containing glycine by using dc and pulse dc current on the beaker level. Micromolds prepared by photolithography allow an accurate pattern transfer for patterned deposition of the material. A flux guide of a magnetic microactuator was chosen as a pattern, and Al{sub 2}O{sub 3} was used as the substrate. Au and Cr were investigated as seed layer materials. The content of Sm in the SmCo films is strongly dependent on the applied cathodic current density. A relative Sm content of up to 13.8 at. % could be determined by energy dispersive x-ray (EDX) spectroscopy. The SmCo thin films were annealed at 560 deg. C in a vacuum oven. Vibrating sample magnetometer (VSM) measurements were applied to characterize the magnetic properties. This film features hard magnetic properties with an intrinsic coercivity H{sub ci} of up to 44 kA/m. Electron probe microanalysis (EPMA) measurements showed that up to 40 at. % of O may be integrated in these films. The phases in the deposited films were determined by applying X-ray diffraction (XRD) measurements. These films consist of a mixture of SmCo alloy, Sm oxide, and Co.

  11. Following the movement of Cu ions in a SSZ-13 zeolite during dehydration, reduction and adsorption: a combined in situ TP-XRD, XANES/DRIFTS study

    SciTech Connect

    Kwak, Ja Hun; Varga, Tamas; Peden, Charles HF; Gao, Feng; Hanson, Jonathan C.; Szanyi, Janos

    2014-05-05

    Cu-SSZ-13 has been shown to possess high activity and superior N2 formation selectivity in the selective catalytic reduction of NOx under oxygen rich conditions. Here, a combination of synchrotron-based (XRD and XANES) and vibrational (DRIFTS) spectroscopy tools have been used to follow the changes in the location and coordination environment of copper ions in a Cu-SSZ-13 zeolite during calcinations, reduction with CO, and adsorption of CO and H2O. XANES spectra collected during these procedures provides critical information not only on the variation in the oxidation state of the copper species in the zeolite structure, but also on the changes in the coordination environment around these ions as they interact with the framework, and with different adsorbates (H2O and CO). Time-resolved XRD data indicate the movement of copper ions and the consequent variation of the unit cell parameters during dehydration. DRIFT spectra provide information about the adsorbed species present in the zeolite, as well as the oxidation states of and coordination environment around the copper ions. A careful analysis of the asymmetric T-O-T vibrations of the CHA framework perturbed by copper ions in different coordination environments proved to be especially informative. The results of this study will aid the identification of the location, coordination and oxidation states of copper ions obtained during in operando catalytic studies. Financial support was provided by the US Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Program. Part of this work (sample preparation) was performed in the Environmental Molecular Sciences Laboratory (EMSL) at Pacific Northwest National Laboratory (PNNL). The EMSL is a national scientific user facility supported by the US DOE, Office of Biological and Environmental Research. PNNL is a multi-program national laboratory operated for the US DOE by Battelle. All of the spectroscopy work reported here was carried out at the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory (BNL). NSLS is a national scientific user facility supported by the US DOE.

  12. Structural changes and thermal stability of charged LiNixMnyCozO2 cathode materials studied by combined in situ time-resolved XRD and mass spectroscopy

    DOE PAGESBeta

    Bak, Seong -Min; Hu, Enyuan; Zhou, Yongning; Yu, Xiqian; Senanayake, Sanjaya D.; Cho, Sung -Jin; Kim, Kwang -Bum; Chung, Kyung Yoon; Yang, Xiao -Qing; Nam, Kyung -Wan

    2014-11-24

    Thermal stability of charged LiNixMnyCozO2 (NMC, with x + y + z = 1, x:y:z = 4:3:3 (NMC433), 5:3:2 (NMC532), 6:2:2 (NMC622), and 8:1:1 (NMC811)) cathode materials is systematically studied using combined in situ time- resolved X-ray diffraction and mass spectroscopy (TR-XRD/MS) techniques upon heating up to 600 °C. The TR-XRD/MS results indicate that the content of Ni, Co, and Mn significantly affects both the structural changes and the oxygen release features during heating: the more Ni and less Co and Mn, the lower the onset temperature of the phase transition (i.e., thermal decomposition) and the larger amount of oxygenmore »release. Interestingly, the NMC532 seems to be the optimized composition to maintain a reasonably good thermal stability, comparable to the low-nickel-content materials (e.g., NMC333 and NMC433), while having a high capacity close to the high-nickel-content materials (e.g., NMC811 and NMC622). The origin of the thermal decomposition of NMC cathode materials was elucidated by the changes in the oxidation states of each transition metal (TM) cations (i.e., Ni, Co, and Mn) and their site preferences during thermal decomposition. It is revealed that Mn ions mainly occupy the 3a octahedral sites of a layered structure (R3?m) but Co ions prefer to migrate to the 8a tetrahedral sites of a spinel structure (Fd3¯m) during the thermal decomposition. Such element-dependent cation migration plays a very important role in the thermal stability of NMC cathode materials. The reasonably good thermal stability and high capacity characteristics of the NMC532 composition is originated from the well-balanced ratio of nickel content to manganese and cobalt contents. As a result, this systematic study provides insight into the rational design of NMC-based cathode materials with a desired balance between thermal stability and high energy density.« less

  13. Three-dimensional atom probe analysis and magnetic properties of Fe85Cu1Si2B8P4 melt spun ribbons

    NASA Astrophysics Data System (ADS)

    Jafari, S.; Beitollahi, A.; Eftekhari Yekta, B.; Ohkubo, T.; Budinsky, Viktoria; Marsilius, Mie; Mollazadeh, S.; Herzer, Giselher; Hono, K.

    2016-03-01

    The effect of phosphorous on the microstructure and magnetic properties of as-spun and flash annealed (389-535 °C for 7 s) Fe85Cu1Si2B8P4 melt spun ribbons were investigated by three-dimensional atom probe (3DAP) and high resolution transmission electron microscopy (HRTEM) techniques. The formation of quasi-amorphous ? -Fe clusters of 3-5 nm size in an amorphous matrix were detected by HRTEM, despite the high quenching rate applied by high wheel speed used. Flash annealing of the as-spun ribbons gave rise to the formation of nanocrystalline ?-Fe (Si) phase in amorphous matrix containing Fe, Si, B and P elements as detected by 3DAP. Comparing 3DAP analysis of the samples annealed at 445 °C and 535 °C revealed that the concentration of P and B in amorphous matrix were increased for the latter. Further, it was shown that P hardly solidified into nanocrystalline phase and partitioned in amorphous phase alongside B atoms leading to the further stabilization of amorphous matrix as confirmed by 3DAP analysis. The highest magnitude of saturation magnetic induction (Bs~1.85 T) and the lowest coercive field (~10-20 A/m) were obtained for the samples annealed above 445 °C, for which noticeable reduction of saturation magnetostriction (? s) were also detected.

  14. Experimental (XRD, FT-IR and UV-Vis) and theoretical modeling studies of Schiff base (E)-N'-((5-nitrothiophen-2-yl)methylene)-2-phenoxyaniline.

    PubMed

    Tanak, Hasan; A?ar, Ay?en Alaman; Büyükgüngör, Orhan

    2014-01-24

    The Schiff base compound (E)-N'-((5-nitrothiophen-2-yl)methylene)-2-phenoxyaniline has been synthesized and characterized by IR, UV-Vis, and X-ray diffraction (XRD) methods. The molecular geometry from X-ray experiment in the ground state has been compared using the density functional theory (DFT) with the 6-311++G(d,p) basis set. The calculated results show that the optimized geometry can well reproduce the crystal structure, and the theoretical vibrational frequency values show good agreement with experimental values. By using TD-DFT method, electronic absorption spectra of the title compound have been predicted and a good agreement with the TD-DFT method and the experimental one is determined. The energetic behavior of the title compound in solvent media has been examined using B3LYP method with the 6-311++G(d,p) basis set by applying the Onsager and the integral equation formalism polarizable continuum model (IEF-PCM). The predicted nonlinear optical properties of the title compound are greater than ones of urea. In addition, DFT calculations of the title compound, molecular electrostatic potential (MEP), natural bond orbital (NBO) and thermodynamic properties were performed at B3LYP/6-311++G(d,p) level of theory. PMID:24096063

  15. Identification of possible sources of atmospheric PM10 using particle size, SEM-EDS and XRD analysis, Jharia Coalfield Dhanbad, India.

    PubMed

    Roy, Debananda; Singh, Gurdeep; Gosai, Nitin

    2015-11-01

    Identification of responsible sources of pollution using physical parameter particulate matter (PM)10 in a critically polluted area is discussed in this paper. Database was generated by Ambient Air Quality Monitoring (AAQM) with respect to PM10 and PM2.5 in 18 monitoring stations at Jharia coalfield as per the siting criteria (IS: 5182, Part XIV) during 2011 to 2012. Identification of the probable sources of PM10 was carried out through particle size, shape, morphology analysis (scanning electron microscopy (SEM)), suitable compounds (X-ray diffraction (XRD)) and elements (energy-dispersive spectroscopy (EDS)). Monitoring stations nearby opencast mine were affected by the big-sized and irregular-shaped particles; on the other hand, monitoring stations nearby city were affected by the small-sized and regular-shaped particles. In a city area, additional sources like diesel generator (DG) set, construction activities, coal burning, etc., were identified. Blistering effects were also observed in the particles from mine fire-affected areas. Using the X-ray diffraction technique, presence of FeS2, CuO, FeSO4 and CuSO4 compounds was observed, which indicates the effects of mine fire on particulate emission due to presence of SO4 (2-) and S(2-) ions. PMID:26450690

  16. Morphology evolution of single-crystalline hematite nanocrystals: magnetically recoverable nanocatalysts for enhanced facet-driven photoredox activity.

    PubMed

    Patra, Astam K; Kundu, Sudipta K; Bhaumik, Asim; Kim, Dukjoon

    2015-12-17

    We have developed a new green chemical approach for the shape-controlled synthesis of single-crystalline hematite nanocrystals in aqueous medium. FESEM, HRTEM and SAED techniques were used to determine the morphology and crystallographic orientations of each nanocrystal and its exposed facets. PXRD and HRTEM techniques revealed that the nanocrystals are single crystalline in nature; twins and stacking faults were not detected in these nanocrystals. The structural, vibrational, and electronic spectra of these nanocrystals were highly dependent on their shape. Different shaped hematite nanocrystals with distinct crystallographic planes have been synthesized under similar reaction conditions, which can be desired as a model for the purpose of properties comparison with the nanocrystals prepared under different reaction conditions. Here we investigated the photocatalytic performance of these different shaped-nanocrystals for methyl orange degradation in the presence of white light (? > 420 nm). In this study, we found that the density of surface Fe(3+) ions in particular facets was the key factor for the photocatalytic activity and was higher on the bitruncated-dodecahedron shape nanocrystals by coexposed {104}, {100} and {001} facets, attributing to higher catalytic activity. The catalytic activity of different exposed facet nanocrystals were as follows: {104} + {100} + {001} (bitruncated-dodecahedron) > {101} + {001} (bitruncated-octahedron) > {001} + {110} (nanorods) > {012} (nanocuboid) which provided the direct evidence of exposed facet-driven photocatalytic activity. The nanocrystals were easily recoverable using an external magnet and reused at least six times without significant loss of its catalytic activity. PMID:26616162

  17. Magnetic investigations

    SciTech Connect

    Bath, G.D.; Jahren, C.E.; Rosenbaum, J.G.; Baldwin, M.J.

    1983-12-31

    Air and ground magnetic anomalies in the Climax stock area of the NTS help define the gross configuration of the stock and detailed configuration of magnetized rocks at the Boundary and Tippinip faults that border the stock. Magnetizations of geologic units were evaluated by measurements of magnetic properties of drill core, minimum estimates of magnetizations from ground magnetic anomalies for near surface rocks, and comparisons of measured anomalies with anomalies computed by a three-dimensional forward program. Alluvial deposits and most sedimentary rocks are nonmagnetic, but drill core measurements reveal large and irregular changes in magnetization for some quartzites and marbles. The magnetizations of quartz monzonite and granodiorite near the stock surface are weak, about 0.15 A/m, and increase at a rate of 0.00196 A/m/m to 1.55 A/m, at depths greater than 700 m (2300 ft). The volcanic rocks of the area are weakly magnetized. Aeromagnetic anomalies 850 m (2800 ft) above the stock are explained by a model consisting of five vertical prisms. Prisms 1, 2, and 3 represent the near surface outline of the stock, prism 4 is one of the models developed by Whitehill (1973), and prism 5 is modified from the model developed by Allingham and Zietz (1962). Most of the anomaly comes from unsampled and strongly-magnetized deep sources that could be either granite or metamorphosed sedimentary rocks. 48 refs., 23 figs., 3 tabs.

  18. Magnetic Properties of Core/Shell Structured Iron/Iron-oxide Nanoparticles Dispersed in Polymer Matrix

    NASA Astrophysics Data System (ADS)

    Nemati Porshokouh, Zohreh; Khurshid, Hafsa; Phan, Manh-Huong; Srikanth, Hariharan

    2014-03-01

    Iron-based nanoparticles (NPs) show interesting magnetic properties for a wide range of applications; however rapid oxidation of iron limits its practical use. Protecting iron with a thin layer of iron-oxide is a possible way to prevent oxidation, forming core/shell (CS) iron/iron-oxide. Due to the different diffusivity rates of the two materials, a gap appears between the core and shell after a period of time (Kirkendall effect), degrading the magnetic properties of the sample. We minimize the Kirkendall effect while retaining good magnetic properties of ~12.5 nm CS iron/iron-oxide NPs by dispersing them into a polymer matrix. Magnetic measurements reveal that after a period of 3 months the blocking temperature (TB) of as-made CS NPs decreases from 107 K to 90 K. The change in TB marks the formation of a gap between the core and shell, which is also evident from HRTEM studies. By contrast, NPs dispersed in RP show no change in TB over the same time period. We repeated experiments with ~10.5 nm CS NPs and the results are consistent. Our study shows the importance of dispersing CS NPs in polymers to preserve desirable magnetic properties for practical applications, ranging from RF sensors and microwave devices to bioengineering.

  19. Development of Superconducting Materials for Use in Magnet Applications: Nb3Sn Flux Pinning and Bi-2212 Magnetic Texturing 

    E-print Network

    Rahmani, David G.

    2010-07-14

    Density MeOH Methanol MJR Modified Jellyroll PIT Powder-in-Tube ppm Parts Per Million RGA Residual Gas Analysis SEM Scanning Electron Microscopy SPD Severe Plastic Deformation T Tesla XRD X-Ray Diffraction vii TABLE OF CONTENTS Page... increased the J c at medium level magnetic fields of approximately 5 Tesla (T); however, the magnetic field at which the peak in J c occurs has not shifted considerably by reducing the grain size [6]. The pinning force for Nb 3 Sn and NbTi are shown...

  20. Planetary Magnetism

    NASA Technical Reports Server (NTRS)

    Connerney, J. E. P.

    2007-01-01

    The chapter on Planetary Magnetism by Connerney describes the magnetic fields of the planets, from Mercury to Neptune, including the large satellites (Moon, Ganymede) that have or once had active dynamos. The chapter describes the spacecraft missions and observations that, along with select remote observations, form the basis of our knowledge of planetary magnetic fields. Connerney describes the methods of analysis used to characterize planetary magnetic fields, and the models used to represent the main field (due to dynamo action in the planet's interior) and/or remnant magnetic fields locked in the planet's crust, where appropriate. These observations provide valuable insights into dynamo generation of magnetic fields, the structure and composition of planetary interiors, and the evolution of planets.

  1. Magnet Healing?

    NASA Astrophysics Data System (ADS)

    Finegold, Leonard

    2000-03-01

    Many people are convinced that static magnets—applied to their skin—will heal ills, and many businesses sell such magnets. The biophysics of such healing was reviewed [1] together with the general biophysics of static fields. Birds and insects do use the earth’s magnetic field for navigation. While insect and frog egg development can clearly be influenced by high fields (7 T and 17 T respectively), there is no experimental evidence that small magnetic fields (of less than 0.5 T) might heal, and much evidence that they cannot heal. A puzzle to the physics community is: How to show laypersons that simple magnets (very probably) do not heal, however attractive that idea might be. [1] L. Finegold, The Physics of "Alternative Medicine": Magnet Therapy, The Scientific Review of Alternative Medicine 3:26-33 (1999).

  2. Magnetic switching

    SciTech Connect

    Kirbie, H.C.

    1989-04-14

    Magnetic switching is a pulse compression technique that uses a saturable inductor (reactor) to pass pulses of energy between two capacitors. A high degree of pulse compression can be achieved in a network when several of these simple, magnetically switched circuits are connected in series. Individual inductors are designed to saturate in cascade as a pulse moves along the network. The technique is particularly useful when a single-pulse network must be very reliable or when a multi-pulse network must operate at a high pulse repetition frequency (PRF). Today, magnetic switches trigger spark gaps, sharpen the risetimes of high energy pulses, power large lasers, and drive high PRF linear induction accelerators. This paper will describe the technique of magnetic pulse compression using simple networks and design equations. A brief review of modern magnetic materials and of their role in magnetic switch design will be presented. 12 refs., 8 figs.

  3. Optical response and magnetic characteristic of samarium doped zinc phosphate glasses containing nickel nanoparticles

    NASA Astrophysics Data System (ADS)

    Azmi, Siti Amlah M.; Sahar, M. R.

    2015-11-01

    A magnetic glass of composition 40ZnO-(58-x) P2O5-1Sm2O3-xNiO, with x=0.0, 1.0, 1.5 and 2.0 mol% is prepared by melt-quenching technique. The glass is characterized by X-ray diffraction, high-resolution transmission electron microscope (HRTEM), photoluminescence (PL) spectroscopy and vibrating sample magnetometer (VSM) analysis. The X-rays diffraction confirms the amorphous nature of the glass while the HRTEM analysis reveals the presence of nickel nanoparticles in the glass samples. High-resolution TEM reveals that the lattice spacing of nickel nanoparticles is 0.35 nm at (100) plane. Photoluminescence emission shows the existence of four peaks that correspond to the transition from the upper level of 4G5/2 to the lower level of 6H5/2, 6H7/2, 6H9/2, and 6H11/2. It is observed that all peaks experience significant quenching effect with the increasing concentration of nickel nanoparticles, suggesting a strong energy transfer from excited samarium ions to the nickel ions. The glass magnetization and susceptibility at 12 kOe at room temperature are found to be in the range of (3.87±0.17×10-2-7.19±0.39×10-2) emu/g and (3.24±0.16×10-6-5.99±0.29×10-6) emu/Oe g respectively. The obtained hysteresis curve indicates that the glass samples are paramagnetic materials. The studied glass can be further used towards the development of magneto-optical functional glass.

  4. Nanostructured lithium oxide-hematite magnetic oxide semiconductors

    NASA Astrophysics Data System (ADS)

    Sorescu, Monica; Bushunow, Vasilii; Diamandescu, Lucian; Tolea, Felicia; Valeanu, Mihaela; Xu, Tianhong

    2015-03-01

    The study aims at exploring the formation of magnetic oxide semiconductors at the nanoscale, which is of crucial importance for catalysis, sensing and electrochemical applications. xLi2O-(1-x)alpha-Fe2O3(x = 0.1, 0.3, 0.5, and 0.7) nanoparticle systems were successfully synthesized by mechanochemical activation of Li2O and alpha-Fe2O3 mixtures for 0-12 hours of ball milling time. X-ray powder diffraction (XRD), Mossbauer spectroscopy and magnetic measurements were used to study the phase evolution. Rietveld refinement of the XRD patterns yielded the values of the particle size as function of composition and milling times. The Mossbauer studies showed that the spectrum of the mechanochemically activated composites evolved from a sextet for hematite to sextets and a doublet upon duration of the milling process with lithium oxide. Magnetic measurements recorded at 5 K to room temperature (RT) in an applied magnetic field of 50,000 Oe showed that the magnetization of the milled samples is larger at low temperatures than at RT and increases with decreasing particle size. Zero field cooling measurements made possible the determination of the blocking temperatures of the specimens as function of ball milling time and evidenced the occurrence of superparamagnetism in the studied samples. NSF-DMR-0854794.

  5. Planetary magnetism

    NASA Technical Reports Server (NTRS)

    Russell, C. T.

    1980-01-01

    Planetary spacecraft have now probed the magnetic fields of all the terrestrial planets, the moon, Jupiter, and Saturn. These measurements reveal that dynamos are active in at least four of the planets, Mercury, the earth, Jupiter, and Saturn but that Venus and Mars appear to have at most only very weak planetary magnetic fields. The moon may have once possessed an internal dynamo, for the surface rocks are magnetized. The large satellites of the outer solar system are candidates for dynamo action in addition to the large planets themselves. Of these satellites the one most likely to generate its own internal magnetic field is Io.

  6. Strange Magnetism

    E-print Network

    Thomas R. Hemmert; Ulf-G. Meissner; Sven Steininger

    1998-11-09

    We present an analytic and parameter-free expression for the momentum dependence of the strange magnetic form factor of the nucleon and its corresponding radius which has been derived in Heavy Baryon Chiral Perturbation Theory. We also discuss a model-independent relation between the isoscalar magnetic and the strange magnetic form factors of the nucleon based on chiral symmetry and SU(3) only. These limites are used to derive bounds on the strange magnetic moment of the proton from the recent measurement by the SAMPLE collaboration.

  7. Magnetic shielding

    DOEpatents

    Kerns, John A. (Livermore, CA); Stone, Roger R. (Walnut Creek, CA); Fabyan, Joseph (Livermore, CA)

    1987-01-01

    A magnetically-conductive filler material bridges the gap between a multi-part magnetic shield structure which substantially encloses a predetermined volume so as to minimize the ingress or egress of magnetic fields with respect to that volume. The filler material includes a heavy concentration of single-magnetic-domain-sized particles of a magnetically conductive material (e.g. soft iron, carbon steel or the like) dispersed throughout a carrier material which is generally a non-magnetic material that is at least sometimes in a plastic or liquid state. The maximum cross-sectional particle dimension is substantially less than the nominal dimension of the gap to be filled. An epoxy base material (i.e. without any hardening additive) low volatility vacuum greases or the like may be used for the carrier material. The structure is preferably exposed to the expected ambient magnetic field while the carrier is in a plastic or liquid state so as to facilitate alignment of the single-magnetic-domain-sized particles with the expected magnetic field lines.

  8. Magnetic shielding

    DOEpatents

    Kerns, J.A.; Stone, R.R.; Fabyan, J.

    1987-10-06

    A magnetically-conductive filler material bridges the gap between a multi-part magnetic shield structure which substantially encloses a predetermined volume so as to minimize the ingress or egress of magnetic fields with respect to that volume. The filler material includes a heavy concentration of single-magnetic-domain-sized particles of a magnetically conductive material (e.g. soft iron, carbon steel or the like) dispersed throughout a carrier material which is generally a non-magnetic material that is at least sometimes in a plastic or liquid state. The maximum cross-sectional particle dimension is substantially less than the nominal dimension of the gap to be filled. An epoxy base material (i.e. without any hardening additive) low volatility vacuum greases or the like may be used for the carrier material. The structure is preferably exposed to the expected ambient magnetic field while the carrier is in a plastic or liquid state so as to facilitate alignment of the single-magnetic-domain-sized particles with the expected magnetic field lines. 3 figs.

  9. Adsorption and Separation of Light Gases on an Amino-Functionalized Metal–Organic Framework: An Adsorption and In Situ XRD Study

    SciTech Connect

    Couck S.; Stavitski E.; Gobehiya, E.; Kirschhock, C.E.A.; Serra-Crespo, P.; Juan-Alcaniz, J.; Martinez Joaristi, A.; Gascon, J.; Kapteijn, F.; Baron, G. V.; Denayer J.F.M.

    2012-02-29

    The NH{sub 2}-MIL-53(Al) metal-organic framework was studied for its use in the separation of CO{sub 2} from CH{sub 4}, H{sub 2}, N{sub 2} C{sub 2}H{sub 6} and C{sub 3}H{sub 8} mixtures. Isotherms of methane, ethane, propane, hydrogen, nitrogen, and CO{sub 2} were measured. The atypical shape of these isotherms is attributed to the breathing properties of the material, in which a transition from a very narrow pore form to a narrow pore form and from a narrow pore form to a large pore form occurs, depending on the total pressure and the nature of the adsorbate, as demonstrated by in-situ XRD patterns measured during adsorption. Apart from CO{sub 2}, all tested gases interacted weakly with the adsorbent. As a result, they are excluded from adsorption in the narrow pore form of the material at low pressure. CO{sub 2} interacted much more strongly and was adsorbed in significant amounts at low pressure. This gives the material excellent properties to separate CO{sub 2} from other gases. The separation of CO{sub 2} from methane, nitrogen, hydrogen, or a combination of these gases has been demonstrated by breakthrough experiments using pellets of NH{sub 2}-MIL-53(Al). The effect of total pressure (1-30 bar), gas composition, temperature (303-403 K) and contact time has been examined. In all cases, CO{sub 2} was selectively adsorbed, whereas methane, nitrogen, and hydrogen nearly did not adsorb at all. Regeneration of the adsorbent by thermal treatment, inert purge gas stripping, and pressure swing has been demonstrated. The NH{sub 2}-MIL-53(Al) pellets retained their selectivity and capacity for more than two years.

  10. Single crystal XRD, vibrational spectra, quantum chemical and thermal studies on a new semi-organic crystal: 4-Aminium antipyrine chloride

    NASA Astrophysics Data System (ADS)

    Chitradevi, A.; Suresh Kumar, S.; Athimoolam, S.; Asath Bahadur, S.; Sridhar, B.

    2015-11-01

    The new semi-organic crystal of 4-aminium antipyrine chloride was grown as a single crystal by slow evaporation solution growth method. The crystal and molecular structure of the grown crystal was determined by single crystal diffraction techniques. The single crystal XRD studies reveal that the phenyl ring and pyrazolone ring of the cation has been inclined at an angle of 52.3 (1)°. The molecular aggregations were stabilized through intricate three dimensional hydrogen bonding network formed by the classical N-H⋯O and N-H⋯Cl hydrogen bonds. The cationic dimer R22(10) motif formed through N-H⋯O intermolecular hydrogen bonds was observed around the inversion center of the unit cell. The amino group from the cation and the chlorine anion was linked through N-H⋯Cl intermolecular hydrogen bond leading to a R24 (8) ring motif. These two ring motifs were extended along the a-axis of the unit cell and forms a hydrophilic layer at z = 0 and 1, which is sandwiched between the hydrophobic layer at z = 1/2. Geometry optimization of the molecules was done by Density Functional Theory (DFT) using the B3LYP function and Hartree-Fock (HF) level with 6-311++G(d,p) basis set. The optimized molecular geometry and computed vibrational spectra were compared with experimental results which show a significant agreement. The natural bond orbital (NBO) analysis was carried out to interpret hyperconjucative interaction and intramolecular charge transfer (ICT). The chemical hardness, electro-negativity and chemical potential of the molecule were carried out by HOMO-LUMO plot. The lower band gap value of the frontier orbitals shows the possible bioactivity of the molecule.

  11. [Spectroscopic analysis of the decay resistance of wood treated with extracts from the xylem of Cinnamomum Camphora with XRD and FTIR approaches].

    PubMed

    Li, Quan; Wang, Xiao-Xian; Lin, Jin-Guo

    2014-03-01

    Four kinds of extracts from the xylem of C. Camphora, ACQ and camphor were selected to make wood preservatives for laboratory toxicity test of wood preservatives for decay fungus. The results showed that the treated blocks with 4% ACQ and 10% methanol extracts could meet the demand of degree I of preservation and showed strong resistance to brown-rot fungus at tack. The wood treated with 4% camphor extracts, 10% ethyl acetate extracts, and 10% acetone extracts reached the demand of degree II and showed moderate decay resistance. The blocks treated with 10% hot water extracts and untreated samples meet the demand of degree III. Through XRD comparison, the author was found that the preservative effects of four extracts are proportional to the degree of crystallinity. Crystallization fields 2 theta diffraction angle were ordered from larger to little as 10% hot wa-ter extracts > untreated samples > 10% acetone extracts > 10% methanol extracts > 1% ethyl acetate extracts. According to FTIR analysis, the amount of degraded cellulose and hemicellulose increased with the decline of characteristic absorption peak at 1,374, 1,160, 1,106, 1,056 and 897 cm(-1), meaning that the preservative effect of corresponding preservatives were getting worse. The peak height of characterization of lignin is higher compared to the untreated wood. I1,510/I1,738, I1,510/I1,374, l51,510/ I1,160 of the treated blocks with 10% methanol extracts and 4% ACQ are the smallest in all the treated blocks, which proved that the degradation ability of brown--rot fungus to the holocellulose is the weakest, and the wood preservative is best. PMID:25208421

  12. Preparation and radiolabeling of surface-modified magnetic nanoparticles with rhenium-188 for magnetic targeted radiotherapy

    NASA Astrophysics Data System (ADS)

    Cao, Jinquan; Wang, Yongxian; Yu, Junfeng; Xia, Jiaoyun; Zhang, Chunfu; Yin, Duanzhi; Häfeli, Urs O.

    2004-06-01

    Magnetite nanoparticles coated with silica were synthesized and characterized by electron microscopic methods (SEM and TEM) and crystal structure analysis (XRD). After surface modification with an amino silane coupling agent, N-[3-(trimethyoxysilyl) propyl]-ethylenediamine (SG-Si900), histidine was covalently linked to the amine group using glutaraldehyde as cross-linker. The magnetic nanoparticles were then radiolabeled with 188Re with a labeling yield of 91.4±0.3% and good stability in vitro. The labeling mechanism is suggested as fac-[ 188Re(CO) 3(H 2O) 3] + core complexed with imidazolyl groups.

  13. Adsorptive removal of heavy metals by magnetic nanoadsorbent: an equilibrium and thermodynamic study

    NASA Astrophysics Data System (ADS)

    Shirsath, D. S.; Shirivastava, V. S.

    2015-11-01

    An efficient and new magnetic nanoadsorbent photocatalyst was fabricated by co-precipitation technique. This research focuses on understanding metal removal process and developing a cost-effective technology for treatment of heavy metal-contaminated industrial wastewater. In this investigation, magnetic nanoadsorbent has been employed for the removal of Zn(II) ions from aqueous solutions by a batch adsorption technique. The adsorption equilibrium data fitted very well to Langmuir and Freundlich adsorption isotherm models. The thermodynamics of Zn(II) ions adsorption onto the magnetic nanoadsorbents indicated that the adsorption was spontaneous, endothermic and physical in nature. Surface morphology of magnetic nanoadsorbent by scanning electron microscopy (SEM) and elemental analysis by EDX technique. The structural and photocatalytic properties of magnetic nanoadsorbent were characterized using X-ray diffraction (XRD) and FTIR techniques. Also, the magnetic properties of synthesized magnetic nanoadsorbent were determined by vibrating spinning magnetometer (VSM).

  14. Magnetic shielding

    DOEpatents

    Kerns, J.A.; Stone, R.R.; Fabyan, J.

    1985-02-12

    A magnetically-conductive filler material bridges the gap between a multi-part magnetic shield structure which substantially encloses a predetermined volume so as to minimize the ingress or egress of magnetic fields with respect to that volume. The filler material includes a heavy concentration of single-magnetic-domain-sized particles of a magnetically conductive material (e.g. soft iron, carbon steel or the like) dispersed throughout a carrier material which is generally a non-magnetic material that is at least sometimes in a plastic or liquid state. The maximum cross-sectional particle dimension is substantially less than the nominal dimension of the gap to be filled. An epoxy base material (i.e. without any hardening additive) low volatility vacuum greases or the like may be used for the carrier material. The structure is preferably exposed to the expected ambient field while the carrier is in a plastic or liquid state so as to facilitate alignment of the single-magnetic-domain-sized particles with the expected magnetic field lines.

  15. Magnetic Recording.

    ERIC Educational Resources Information Center

    Lowman, Charles E.

    A guide to the technology of magnetic recorders used in such fields as audio recording, broadcast and closed-circuit television, instrumentation recording, and computer data systems is presented. Included are discussions of applications, advantages, and limitations of magnetic recording, its basic principles and theory of operation, and its…

  16. Electrical and magnetic properties of chitosan-magnetite nanocomposites

    NASA Astrophysics Data System (ADS)

    Bhatt, Aarti S.; Krishna Bhat, D.; Santosh, M. S.

    2010-04-01

    Magnetite powders in nanometer size have been synthesized by the hydrothermal process. Various magnetic films of chitosan and the synthesized magnetite nanopowders containing different concentrations of the latter were prepared by ultrasonication route. The X-ray diffraction (XRD) studies and the transmission electron microscopy (TEM) images showed that the synthesized magnetite particles had 80 nm dimensions. The band gap of the composites was evaluated using the UV-visible Spectroscopy. The influence of magnetite content on the magnetic properties of the composite showed a decrease in the saturation magnetization with the decrease in the magnetic content. The effect of magnetite content on the dielectric properties of the polymer film at different frequencies from 0.01 to 105 Hz was studied using an electrochemical impedance spectroscopy. The possible mechanism for the observed electrical properties of the composite films was discussed.

  17. Magnetic single-enzyme nanoparticles with high activity and stability

    SciTech Connect

    Yang Zhengpeng; Si Shihui Zhang Chunjing

    2008-02-29

    Magnetic single-enzyme nanoparticles (SENs) encapsulated within a composite inorganic/organic polymer network were fabricated via the surface modification and in situ aqueous polymerization of separate enzyme molecule. The resultant nanoparticles were characterized by transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectrometer and X-ray diffraction (XRD). These particles are almost spherical in shape and have a unique size of about 50 nm in diameter. Electrical and magnetic measurements reveal that the magnetic SENs have a conductivity of 2.7 x 10{sup -3} S cm{sup -1}, and are superparamagnetic with a saturation magnetization of 14.5 emu g{sup -1} and a coercive force of 60 Oe. Compared with free enzyme, encapsulated enzyme exhibits a strong tolerance to the variation of solution pH, high temperature, organic solvent and long-term storage, thus showing significantly enhanced enzyme performance and stability.

  18. Magnetic nanotubes

    DOEpatents

    Matsui, Hiroshi (Glen Rock, NJ); Matsunaga, Tadashi (Tokyo, JP)

    2010-11-16

    A magnetic nanotube includes bacterial magnetic nanocrystals contacted onto a nanotube which absorbs the nanocrystals. The nanocrystals are contacted on at least one surface of the nanotube. A method of fabricating a magnetic nanotube includes synthesizing the bacterial magnetic nanocrystals, which have an outer layer of proteins. A nanotube provided is capable of absorbing the nanocrystals and contacting the nanotube with the nanocrystals. The nanotube is preferably a peptide bolaamphiphile. A nanotube solution and a nanocrystal solution including a buffer and a concentration of nanocrystals are mixed. The concentration of nanocrystals is optimized, resulting in a nanocrystal to nanotube ratio for which bacterial magnetic nanocrystals are immobilized on at least one surface of the nanotubes. The ratio controls whether the nanocrystals bind only to the interior or to the exterior surfaces of the nanotubes. Uses include cell manipulation and separation, biological assay, enzyme recovery, and biosensors.

  19. Magnetically separable nanocomposites with photocatalytic activity under visible light for the selective transformation of biomass-derived platform molecules

    EPA Science Inventory

    Novel magnetically separable TiO2-guanidine-(Ni,Co)Fe2O4 nanomaterials were prepared and characterised by a series of techniques including XRD, SEM, TEM, N2 physisorption as well as XPS and subsequently tested for their photocatalytic activities in the selective transformation of...

  20. Biocellulose-based flexible magnetic paper

    NASA Astrophysics Data System (ADS)

    Barud, H. S.; Tercjak, A.; Gutierrez, J.; Viali, W. R.; Nunes, E. S.; Ribeiro, S. J. L.; Jafellici, M.; Nalin, M.; Marques, R. F. C.

    2015-05-01

    Biocellulose or bacterial cellulose (BC) is a biocompatible (nano) material produced with a three-dimensional network structure composed of microfibrils having nanometric diameters obtained by the Gluconacetobacter xylinus bacteria. BC membranes present relatively high porosity, allowing the incorporation or synthesis in situ of inorganic nanoparticles for multifunctional applications and have been used as flexible membranes for incorporation of magnetic nanocomposite. In this work, highly stable superparamagnetic iron oxide nanoparticles (SPION), functionalized with polyethylene glycol (PEG), with an average diameter of 5 nm and a saturation magnetization of 41 emu/g at 300 K were prepared. PEG-Fe2O3 hybrid was dispersed by mixing a pristine BC membrane in a stable aqueous dispersion of PEG-SPION. The PEG chains at PEG-SPION's surface provide a good permeability and strong affinity between the BC chains and SPION through hydrogen-bonding interactions. PEG-SPION also allow the incorporation of higher content of nanoparticles without compromising the mechanical properties of the nanocomposite. Structural and magnetic properties of the composite have been characterized by XRD, SEM, energy-dispersive X-ray spectroscopy (EDX), magnetization, Raman spectroscopy, and magnetic force microscopy.

  1. Modal mineralogy of CM chondrites by X-ray diffraction (PSD-XRD): Part 2. Degree, nature and settings of aqueous alteration

    NASA Astrophysics Data System (ADS)

    Howard, K. T.; Benedix, G. K.; Bland, P. A.; Cressey, G.

    2011-05-01

    Within 5 million years after formation of calcium aluminium rich inclusions (CAI), high temperature anhydrous phases were transformed to hydrous phyllosilicates, mostly serpentines, which dominate the matrices of the most primitive carbonaceous chondrites. CMs are the largest group of meteorites to provide samples of this material. To understand the nature of the availability, and role of H 2O in the early solar system - as well as the settings of aqueous alteration - defining CM petrogenesis is critical. By Position Sensitive Detector X-ray Diffraction (PSD-XRD), we determine the modal abundance of crystalline phases present in volumes >1% for a suite of CMs - extending Part 1 of this work that dealt only with CM2 falls ( Howard et al., 2009) to now include CM2 and CM1 finds. CM2 samples contain 13-31% Fe,Mg silicates (olivine + pyroxene) and from 67% to 82% total phyllosilicate (mean 75% ± 1.3 2 ?). CM1 samples contain 6-10% olivine + pyroxene and 86-88% total phyllosilicate. Magnetite (0.6-5.2%), sulphide (0.6-3.9%), calcite (0-1.9%) and gypsum (0-0.8%) are minor phases across all samples. Since phyllosilicate forms from hydration of anhydrous Fe,Mg silicates (olivine + pyroxene), the ratio of total phyllosilicate to total anhydrous Fe,Mg silicate defines the degree of hydration and the following sequence results (in order of increasing hydration): QUE 97990 < Y 791198 < Murchison < Murray < Mighei < ALHA 81002 < Nogoya ? Cold Bokkeveld ? Essebi < QUE 93005 < ALH 83100 < MET 01070 < SCO 06043. High activities of Al (mostly from reactive mesostasis) and Si help to explain the composition and structure of CM serpentines that are distinct from terrestrial standards. Our data allows inference as to CM mineralogy at the point of accretion and challenges the conceptual validity of progressive alteration sequences. Modal mineralogy also provides new insights into CM petrogenesis and hints at a component of aqueous alteration occurring in the nebula, in addition to on the CM parent body(ies).

  2. The CheMin XRD on the Mars Science Laboratory Rover Curiosity: Construction, Operation, and Quantitative Mineralogical Results from the Surface of Mars

    NASA Technical Reports Server (NTRS)

    Blake, David F.

    2015-01-01

    The Mars Science Laboratory mission was launched from Cape Canaveral, Florida on Nov. 26, 2011 and landed in Gale crater, Mars on Aug. 6, 2012. MSL's mission is to identify and characterize ancient "habitable" environments on Mars. MSL's precision landing system placed the Curiosity rover within 2 km of the center of its 20 X 6 km landing ellipse, next to Gale's central mound, a 5,000 meter high pile of laminated sediment which may contain 1 billion years of Mars history. Curiosity carries with it a full suite of analytical instruments, including the CheMin X-ray diffractometer, the first XRD flown in space. CheMin is essentially a transmission X-ray pinhole camera. A fine-focus Co source and collimator transmits a 50µm beam through a powdered sample held between X-ray transparent plastic windows. The sample holder is shaken by a piezoelectric actuator such that the powder flows like a liquid, each grain passing in random orientation through the beam over time. Forward-diffracted and fluoresced X-ray photons from the sample are detected by an X-ray sensitive Charge Coupled Device (CCD) operated in single photon counting mode. When operated in this way, both the x,y position and the energy of each photon are detected. The resulting energy-selected Co Kalpha Debye-Scherrer pattern is used to determine the identities and amounts of minerals present via Rietveld refinement, and a histogram of all X-ray events constitutes an X-ray fluorescence analysis of the sample.The key role that definitive mineralogy plays in understanding the Martian surface is a consequence of the fact that minerals are thermodynamic phases, having known and specific ranges of temperature, pressure and composition within which they are stable. More than simple compositional analysis, definitive mineralogical analysis can provide information about pressure/temperature conditions of formation, past climate, water activity and the like. Definitive mineralogical analyses are necessary to establish the origin or provenance of a sample. The search for evidence of extant or extinct life on Mars will initially be a search for evidence of present or past conditions supportive of life (e.g., evidence of water), not for life itself.Results of the first 1,000 sols (Mars days) will be discussed, including the discovery of the first habitable environment on Mars.

  3. New iron-based SiC spherical composite magnetic abrasive for magnetic abrasive finishing

    NASA Astrophysics Data System (ADS)

    Zhang, Guixiang; Zhao, Yugang; Zhao, Dongbiao; Zuo, Dunwen; Yin, Fengshi

    2013-03-01

    SiC magnetic abrasive is used to polish surfaces of precise, complex parts which are hard, brittle and highly corrosion-resistant in magnetic abrasive finishing(MAF). Various techniques are employed to produce this magnetic abrasive, but few can meet production demands because they are usually time-consuming, complex with high cost, and the magnetic abrasives made by these techniques have irregular shape and low bonding strength that result in low processing efficiency and shorter service life. Therefore, an attempt is made by combining gas atomization and rapid solidification to fabricate a new iron-based SiC spherical composite magnetic abrasive. The experimental system to prepare this new magnetic abrasive is constructed according to the characteristics of gas atomization and rapid solidification process and the performance requirements of magnetic abrasive. The new iron-based SiC spherical composite magnetic abrasive is prepared successfully when the machining parameters and the composition proportion of the raw materials are controlled properly. Its morphology, microstructure, phase composition are characterized by scanning electron microscope(SEM) and X-ray diffraction(XRD) analysis. The MAF tests on plate of mold steel S136 are carried out without grinding lubricant to assess the finishing performance and service life of this new SiC magnetic abrasive. The surface roughness( R a) of the plate worked is rapidly reduced to 0.051 ?m from an initial value of 0.372 ?m within 5 min. The MAF test is carried on to find that the service life of this new SiC magnetic abrasive reaches to 155 min. The results indicate that this process presented is feasible to prepare the new SiC magnetic abrasive; and compared with previous magnetic abrasives, the new SiC spherical composite magnetic abrasive has excellent finishing performance, high processing efficiency and longer service life. The presented method to fabricate magnetic abrasive through gas atomization and rapid solidification presented can significantly improve the finishing performance and service life of magnetic abrasive, and provide a more practical approach for large-scale industrial production of magnetic abrasive.

  4. Lunar magnetism

    NASA Technical Reports Server (NTRS)

    Hood, L. L.; Sonett, C. P.; Srnka, L. J.

    1984-01-01

    Aspects of lunar paleomagnetic and electromagnetic sounding results which appear inconsistent with the hypothesis that an ancient core dynamo was the dominant source of the observed crustal magnetism are discussed. Evidence is summarized involving a correlation between observed magnetic anomalies and ejecta blankets from impact events which indicates the possible importance of local mechanisms involving meteoroid impact processes in generating strong magnetic fields at the lunar surface. A reply is given to the latter argument which also presents recent evidence of a lunar iron core.

  5. Magnetic Bearing

    NASA Technical Reports Server (NTRS)

    1996-01-01

    AVCON, Inc. produces advanced magnetic bearing systems for industrial use, offering a unique technological approach based on contract work done at Marshall Space Flight Center and Lewis Research Center. Designed for the turbopump of the Space Shuttle main engine, they are now used in applications such as electric power generation, petroleum refining, machine tool operation and natural gas pipelines. Magnetic bearings support moving machinery without physical contact; AVCON's homopolar approach is a hybrid of permanent and electromagnets which are one-third the weight, smaller and more power- efficient than previous magnetic bearings.

  6. Microporous Magnets

    SciTech Connect

    Dechambenoit, Pierre; Long, Jeffrey R

    2011-01-01

    Combining porosity and magnetic ordering in a single material presents a significant challenge since magnetic exchange generally requires short bridges between the spin carriers, whereas porosity usually relies on the use of long diamagnetic connecting ligands. Despite this apparent incompatibility, notable successes have been achieved of late in generating truly microporous solids with high magnetic ordering temperatures. In this critical review, we give an overview of this emerging class of multifunctional materials, with particular emphasis on synthetic strategies and possible routes to new materials with improved properties (149 references).

  7. Nano Ag-doped ZnO particles magnetic, optical and structural studies

    NASA Astrophysics Data System (ADS)

    Shah, A. H.; Manikandan, E.; Ahmed, M. Basheer; Irdosh, M.

    2013-02-01

    In this work, we report the influences of annealing effects were explored on the crystallinity, morphology and magnetic properties of Ag doped ZnO nanoparticles. The XRD, SEM and vibrating sample magnetometer (VSM) were used to characterize the crystal structures, surface morphology and magnetic properties of doped and pure ZnO nanoparticles (NPs). As synthesized and annealed ZnO NPs were found hexagonal wurtzite crystal structure and the grain size increases while lattice strain decreases due to annealing. From TEM observation annealed samples were shown nanorod like structure found with Ag NPs embedded on the surface. Due to annealing effect, Ag-ZnO shows higher saturation magnetization at RT.

  8. Superconducting magnets

    SciTech Connect

    Willen, E.; Dahl, P.; Herrera, J.

    1985-01-01

    This report provides a self-consistent description of a magnetic field in the aperture of a superconducting magnet and details how this field can be calculated in a magnet with cos theta current distribution in the coils. A description of an apparatus that can be used to measure the field uniformity in the aperture has been given. Finally, a detailed description of the magnet being developed for use in the Superconducting Super Collider is given. When this machine is built, it will be by far the largest application of superconductivity to date and promises to make possible the experimental discoveries needed to understand the basic laws of nature governing the world in which we live.

  9. Magnetic Resonance

    Cancer.gov

    Focus Group on Magnetic Resonance Spectroscopy (MRS) in Clinical Oncology(April 1999) To explore the technical requirements for MRS and the application of hydrogen and multinuclear spectroscopy for tumor response to therapy.

  10. Magnetic monopoles

    SciTech Connect

    Fryberger, D.

    1984-12-01

    In this talk on magnetic monopoles, first the author briefly reviews some historical background; then, the author describes what several different types of monopoles might look like; and finally the author discusses the experimental situation. 81 references.

  11. MAGNETIC IMAGING OF NANOCOMPOSITE MAGNETS

    SciTech Connect

    VOLKOV,V.V.ZHU,Y.

    2003-08-03

    Understanding the structure and magnetic behavior is crucial for optimization of nanocomposite magnets with high magnetic energy products. Many contributing factors such as phase composition, grain size distribution and specific domain configurations reflect a fine balance of magnetic energies at nanometer scale. For instance, magnetocrystalline anisotropy of grains and their orientations, degree of exchange coupling of magnetically soft and hard phases and specific energy of domain walls in a material. Modern microscopy, including Lorentz microscopy, is powerful tool for visualization and microstructure studies of nanocomposite magnets. However, direct interpretation of magnetically sensitive Fresnel/Foucault images for nanomagnets is usually problematic, if not impossible, because of the complex image contrast due to small grain size and sophisticated domain structure. Recently we developed an imaging technique based on Lorentz phase microscopy [l-4], which allows bypassing many of these problems and get quantitative information through magnetic flux mapping at nanometer scale resolution with a magnetically calibrated TEM [5]. This is our first report on application of this technique to nanocomposite magnets. In the present study we examine a nanocomposite magnet of nominal composition Nd{sub 2}Fe{sub 14+{delta}}B{sub 1.45} (14+{delta}=23.3, i.e. ''hard'' Nd{sub 2}Fe{sub 14}B-phase and 47.8 wt% of ''soft'' {alpha}-Fe phase ({delta}=9.3)), produced by Magnequench International, Inc. Conventional TEM/HREM study (Fig. 1-2) suggests that material has a bimodal grain-size distribution with maximum at d{sub max}=25 nm for Nd{sub 2}Fe{sub 14}B phase and d{sub max} = 15 nm for {alpha}-Fe phase (Fig.1c, Fig.2) in agreement with synchrotron X-ray studies (d{sub max}=23.5 nm for Nd{sub 2}Fe{sub 14}B [6]). Lattice parameters for Nd{sub 2}Fe{sub 14}B phase are a=8.80 and c=12.2 {angstrom}, as derived from SAED ring patterns (Fig.1a), again in good agreement with X-ray data. The fraction of large particles (of size 250 nm) is less then 57% of total amount of particles (Fig.1c, arrowed). Our new imaging technique allows visualization of domain structure in nanomagnets (Fig.3) in color code. Both projected magnetization and magnetic flux maps (Fig.3) reconstructed using Lorentz phase microscopy suggest a complex domain structure with an average domain size about 100x(100{approx}200) nm{sup 2} in a non-magnetized state. Large particles of darker contrast (of size {ge}50 nm, presumably {alpha}-Fe precipitates) or clusters of such particles act as effective concentrators for magnetic flux in nanocomposite matrix. The measured relative local-flux concentration by factor of 1.28 agrees well with theoretical ratio B{sub sat}({alpha}-Fe)/B{sub sat}(Nd{sub 2}Fe{sub 14}B)=1.31, strongly suggesting clustering of {alpha}-Fe particles that may have a detrimental effect on nanomagnet coercivity. Other smaller {alpha}-Fe particles (< 25 nm) do not disturb flux distribution, hence, they are magnetically coupled to Nd-Fe-B matrix grains as it was postulated by spring-exchange mechanism for nanocomposite magnets.

  12. Synthesis of magnetic nanofibers using femtosecond laser material processing in air

    PubMed Central

    2011-01-01

    In this study, we report formation of weblike fibrous nanostructure and nanoparticles of magnetic neodymium-iron-boron (NdFeB) via femtosecond laser radiation at MHz pulse repetition frequency in air at atmospheric pressure. Scanning electron microscopy (SEM) analysis revealed that the nanostructure is formed due to aggregation of polycrystalline nanoparticles of the respective constituent materials. The nanofibers diameter varies between 30 and 70 nm and they are mixed with nanoparticles. The effect of pulse to pulse separation rate on the size of the magnetic fibrous structure and the magnetic strength was reported. X-ray diffraction (XRD) analysis revealed metallic and oxide phases in the nanostructure. The growth of magnetic nanostructure is highly recommended for the applications of magnetic devices like biosensors and the results suggest that the pulsed-laser method is a promising technique for growing nanocrystalline magnetic nanofibers and nanoparticles for biomedical applications. PMID:21711890

  13. ?-MnAl with high coercivity and saturation magnetization

    NASA Astrophysics Data System (ADS)

    Wei, J. Z.; Song, Z. G.; Yang, Y. B.; Liu, S. Q.; Du, H. L.; Han, J. Z.; Zhou, D.; Wang, C. S.; Yang, Y. C.; Franz, A.; Többens, D.; Yang, J. B.

    2014-12-01

    In this paper, high purity ?-Mn54Al46 and Mn54-xAl46Cxalloys were successfully prepared using conventional arc-melting, melt-spinning, and heat treatment process. The magnetic and the structural properties were examined using x-ray diffraction (XRD), powder neutron diffraction and magnetic measurements. A room temperature saturation magnetization of 650.5 kAm-1, coercivity of 0.5 T, and a maximum energy product of (BH)max = 24.7 kJm-3 were achieved for the pure Mn54Al46 powders without carbon doping. The carbon substituted Mn54-xAl46Cx, however, reveals a lower Curie temperature but similar saturation magnetization as compared to the carbon-free sample. The electronic structure of MnAl shows that the Mn atom possesses a magnetic moment of 2.454 ?B which results from strong hybridization between Mn-Al and Mn-Mn. We also investigated the volume and c/a ratio dependence of the magnetic moments of Mn and Al. The results indicate that an increase in the intra-atomic exchange splitting due to the cell volume expansion, leads to a large magnetic moment for the Mn atom. The Mn magnetic moment can reach a value of 2.9 ?B at a volume expansion rate of ?V/V ? 20%.

  14. Color-tunable magnetic and luminescent hybrid nanoparticles: Synthesis, optical and magnetic properties

    NASA Astrophysics Data System (ADS)

    Lou, Lei; Yu, Ke; Wang, Yiting; Zhu, Ziqiang

    2012-02-01

    A facile method for synthesizing color-tunable magnetic and luminescent hybrid bifunctional nanoparticles is presented. A series of CdSe/ZnS core-shell quantum dots (QDs) with different sizes were successfully fabricated and self-assembled to Fe3O4 magnetic nanoparticles (MNP), which were subsequently coated with a polyethyleneimine (PEI) layer to prevent large aggregates. The hydrophobic QDs capped with trioctylphosphine oxide (TOPO) formed a coating surrounding MNP, and were transferred into hydrophilic phase by PEI with high efficiency. The samples were characterized by TEM, FT-IR, XRD, EDS, UV-vis spectrophotometer, fluorescent spectrophotometer and PPMS. Results show that the original properties of the nanoparticles were well-preserved in the hybrid structure. All MNP-QDs hybrid nanoparticles showed paramagnetic behavior and the nanocomposites were still highly luminescent with no shift in the PL peak position.

  15. Magnetism. Blowing magnetic skyrmion bubbles.

    PubMed

    Jiang, Wanjun; Upadhyaya, Pramey; Zhang, Wei; Yu, Guoqiang; Jungfleisch, M Benjamin; Fradin, Frank Y; Pearson, John E; Tserkovnyak, Yaroslav; Wang, Kang L; Heinonen, Olle; te Velthuis, Suzanne G E; Hoffmann, Axel

    2015-07-17

    The formation of soap bubbles from thin films is accompanied by topological transitions. Here we show how a magnetic topological structure, a skyrmion bubble, can be generated in a solid-state system in a similar manner. Using an inhomogeneous in-plane current in a system with broken inversion symmetry, we experimentally "blow" magnetic skyrmion bubbles from a geometrical constriction. The presence of a spatially divergent spin-orbit torque gives rise to instabilities of the magnetic domain structures that are reminiscent of Rayleigh-Plateau instabilities in fluid flows. We determine a phase diagram for skyrmion formation and reveal the efficient manipulation of these dynamically created skyrmions, including depinning and motion. The demonstrated current-driven transformation from stripe domains to magnetic skyrmion bubbles could lead to progress in skyrmion-based spintronics. PMID:26067256

  16. Neutrino magnetic moment in a magnetized plasma

    E-print Network

    N. V. Mikheev; E. N. Narynskaya

    2010-11-08

    The contribution of a magnetized plasma to the neutrino magnetic moment is calculated. It is shown that only part of the additional neutrino energy in magnetized plasma connecting with its spin and magnetic field strength defines the neutrino magnetic moment. It is found that the presence of magnetized plasma does not lead to the considerable increase of the neutrino magnetic moment in contrast to the results presented in literature previously.

  17. Synthesis of Mn-doped ZnO diluted magnetic semiconductors in the presence of ethyl acetoacetate under solvothermal conditions

    NASA Astrophysics Data System (ADS)

    Jing, Chengbin; Jiang, Yingjing; Bai, Wei; Chu, Junhao; Liu, Aiyun

    2010-08-01

    Mn-doped ZnO samples with 5%, 20% and 40% nominal Mn concentrations were prepared in the presence of ethyl acetoacetate under solvothermal conditions. UV absorption spectroscopic analysis discloses that chemical modification was achieved by reaction of Zn or Mn precursor with ethyl acetoacetate in ethanol medium. XRD and HRTEM characterizations indicate that ZnMnO 3 impurity phase was formed in the 20% and 40% Mn-doped ZnO samples while no secondary phase was present in the 5% Mn-doped sample. The 5% Mn-doped sample consists of spheroid-like particles with size of 10-50 nm and has a real Mn concentration of 3.2%. Ferromagnetism and paramagnetism coexist in the 5% Mn-doped ZnO sample at room-temperature, which may arise from ferromagnetic exchange interaction as well as small secondary phases. The 20% and 40% Mn-doped samples show large paramagnetic effects at room temperature. Small paramagnetic secondary phases and clustering of Mn are probably responsible for this.

  18. Temperature-induced phenomena in systems of magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Bhuiya, Abdul Wazed

    Magnetic nanoparticle ensembles have received a lot of attention, stemming in part from their current and potential applications in biomedicine and in the development of high-density magnetic storage media. Key to the functionality of these systems are microscopic structures and mechanisms that make them exhibit unique properties and behave differently from their bulk counterparts. We studied microscopic structures and processes that dictate macroscopic properties, behavior and functionality of magnetic nanoparticle ensembles. As the temperature T strongly influences the magnetic behavior of these systems, we studied temperature dependent magnetic properties using AC-susceptibility and DC-magnetization measurements carried out over a broad range of temperatures, between 3 and 300 K. We extracted structural information from X-ray diffraction (XRD) and direct imaging techniques and correlate it with magnetic properties, in an attempt at better understanding the microscopic structures and magnetic mechanisms responsible for the macroscopic magnetic behavior. We studied ensembles of magnetic nanoparticles: nickel ferrite immobilized in a solid matrix and cobalt ferrite immersed in carrier fluid respectively, in order to explore their potential use in biomedical applications and magnetic recording. For both NiFe2O4(NFO) and Co0.2Fe2.8O4 (CFO) relaxation mechanisms were determined. Structural properties and average particle sizes were derived from XRD, including synchrotron XRD, and direct imaging techniques such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Temperature dependent magnetic measurements, FC-ZFC DC magnetometry, as well as AC complex susceptibility measurements at frequencies between 10 and 10,000 Hz were carried out within the temperature range 3Kmagnetization and AC susceptibility measurements were performed using a Physical Property Measurement System (PPMS), which allows measurements in magnetic fields up to 9T and within a temperature range between 2 and 350 K. For NFO, besides the expected blocking of the superspin, observed at T1 ? 45 K, we found that the system undergoes a magnetic transition at T2 ? 6 K. For the latter, frequency- and temperature-resolved dynamic susceptibility data reveal characteristics that are unambiguously related to collective spin freezing: the relative variation (per frequency decade) of the in-phase-susceptibility peak temperature is ˜0.025, critical dynamics analysis yields an exponent zv = 9.6 and a zero-field freezing temperature TF = 5.8 K, and, in a magnetic field, TF (H) is excellently described by the de Almeida-Thouless line deltaT F infinity H2/3. Moreover, out-of-phase-susceptibility vs. temperature datasets collected at different frequencies collapse on a universal dynamic scaling curve. All these observations indicate the existence of a spin-glass-like surface layer that surrounds the superparamagnetic core and undergoes a transition to a frozen state upon cooling below 5.8 K. For the CFO ferrofluid, we used temperature- and frequency-resolved AC-susceptibility measurements to investigate its magnetic relaxation above the freezing point of the liquid carrier. Our data show that both the Neel and the Brown relaxation mechanisms are operative at temperatures in the vicinity of the out-of-phase (imaginary) susceptibility peak. We separate the contributions of the two mechanisms to the overall-relaxation time, and demonstrate that Brownian relaxation plays a dominant role at all temperatures within this high-dissipation regime.

  19. Magnetic fluids

    NASA Astrophysics Data System (ADS)

    Rosensweig, R. E.

    1982-10-01

    An overview of studies done on ferrofluids is presented, and recently discovered technological uses for such a fluid are examined. By interacting magnetization and pressure, a ferrofluid plug, held in place by a focused magnetic field imposed from the outside, serves as an airtight seal in rotating machinery. A 160 stage rotary seal has withstood a pressure differential of 66 atmospheres. The fluid has also proved useful in the design of loudspeakers, as it does not drip out of the gap in the cylindrical permanent magnet which allows the voice coil to move, thus serving as a coolant for the system. Finally, the fluid can be used to separate materials according to density, as the magnetic-levitation forces that can be established in the fluid are strong enough to float materials of any density. Other applications are being explored, such as an induced convection that can be much more vigorous than simple gravity convection when a gradient magnetic field is applied to a heated ferrofluid.

  20. Magnetic liposomes for colorectal cancer cells therapy by high-frequency magnetic field treatment

    NASA Astrophysics Data System (ADS)

    Hardiansyah, Andri; Huang, Li-Ying; Yang, Ming-Chien; Liu, Ting-Yu; Tsai, Sung-Chen; Yang, Chih-Yung; Kuo, Chih-Yu; Chan, Tzu-Yi; Zou, Hui-Ming; Lian, Wei-Nan; Lin, Chi-Hung

    2014-09-01

    In this study, we developed the cancer treatment through the combination of chemotherapy and thermotherapy using doxorubicin-loaded magnetic liposomes. The citric acid-coated magnetic nanoparticles (CAMNP, ca. 10 nm) and doxorubicin were encapsulated into the liposome (HSPC/DSPE/cholesterol = 12.5:1:8.25) by rotary evaporation and ultrasonication process. The resultant magnetic liposomes ( ca. 90 to 130 nm) were subject to characterization including transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD), zeta potential, Fourier transform infrared (FTIR) spectrophotometer, and fluorescence microscope. In vitro cytotoxicity of the drug carrier platform was investigated through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay using L-929 cells, as the mammalian cell model. In vitro cytotoxicity and hyperthermia (inductive heating) studies were evaluated against colorectal cancer (CT-26 cells) with high-frequency magnetic field (HFMF) exposure. MTT assay revealed that these drug carriers exhibited no cytotoxicity against L-929 cells, suggesting excellent biocompatibility. When the magnetic liposomes with 1 ?M doxorubicin was used to treat CT-26 cells in combination with HFMF exposure, approximately 56% cells were killed and found to be more effective than either hyperthermia or chemotherapy treatment individually. Therefore, these results show that the synergistic effects between chemotherapy (drug-controlled release) and hyperthermia increase the capability to kill cancer cells.

  1. Studies on the self-catalyzed Knoevenagel condensation, characterization, DPPH radical scavenging activity, cytotoxicity, and molecular properties of 5-arylidene-2,2-dimethyl-1,3-dioxane-4,6-diones using single crystal XRD and DFT techniques

    NASA Astrophysics Data System (ADS)

    Suresh Kumar, G. S.; Antony Muthu Prabhu, A.; Bhuvanesh, N.

    2014-10-01

    We have studied the self-catalyzed Knoevenagel condensation, spectral characterization, DPPH radical scavenging activity, cytotoxicity, and molecular properties of 5-arylidene-2,2-dimethyl-1,3-dioxane-4,6-diones using single crystal XRD and DFT techniques. In the absence of any catalyst, a series of novel 5-arylidene-2,2-dimethyl-1,3-dioxane-4,6-diones were synthesized using Meldrum’s acid and formylphenoxyaliphatic acid(s) in water. These molecules are arranged in the dimer form through intermolecular H-bonding in the single crystal XRD structure. Compounds have better DPPH radical scavenging activity and cytotoxicity against A431 cancer cell line. The optimized molecular structure, natural bond orbital analysis, electrostatic potential map, HOMO-LUMO energies, molecular properties, and atomic charges of these molecules have been studied by performing DFT/B3LYP/3-21G(*) level of theory in gas phase.

  2. Magnetic birefringence of iron oxyhydroxide nanoparticles stabilised by sucrose

    NASA Astrophysics Data System (ADS)

    Koralewski, M.; Pochylski, M.; Gierszewski, J.

    2011-05-01

    Magnetically induced optical birefringence is used to investigate pharmaceutically important iron-sucrose aqueous suspensions. XRD and TEM measurements of the system of oxyhydroxide particles stabilised by sucrose have shown that this system contains iron oxyhydroxide in the form of 2-5 nm particles. The mineral form of the iron-core is suggested to be akaganeite. Anisotropy of the optical polarizability and magnetic susceptibility of akaganeite nanoparticles are calculated. The permanent dipole moment obtained for the nanoparticles studied was found to be negligible, in agreement with the characteristic superparamagnetic behaviour of the magnetic nanoparticles observed at room temperature. The Neel temperature of these nanoparticles is estimated as below 276 K. The results obtained are discussed against a background of the earlier studies of similar nanoscale systems.

  3. Enhancement of the magnetic properties of Al/La multiferroic

    NASA Astrophysics Data System (ADS)

    Ahmed, M. A.; Okasha, N.; Hussein, B.

    2012-08-01

    Nanosized multiferroic La1-xAlxFeO3 (0.00?x?0.20) samples were successfully synthesized by the citrate technique without subsequent heat treatment. All the prepared samples revealed single phase orthorhombic structure of space group Pbnm. XRD data revealed that the lattice parameters (a) decrease with increasing Al content. The magnetic susceptibility (?M) was enhanced significantly from 0.36 to 0.68 emu/g mole from LaFeO3 to La0.8Al0.2FeO3 respectively. The values of magnetization (M) and effective magnetic moment (?eff) were found to increase with increasing Al content. The enhancement of the physical and structural properties of the investigated multiferroic is possibly due to the changes in the lattice parameters, tolerance factor as well as crystallite size caused by aluminum substitution.

  4. Magnetic particles

    NASA Technical Reports Server (NTRS)

    Chang, Manchium (Inventor); Colvin, Michael S. (Inventor)

    1989-01-01

    Magnetic polymer particles are formed by swelling porous, polymer particles and impregnating the particles with an aqueous solution of precursor magnetic metal salt such as an equimolar mixture of ferrous chloride and ferric chloride. On addition of a basic reagent such as dilute sodium hydroxide, the metal salts are converted to crystals of magnetite which are uniformly contained througout the pores of the polymer particle. The magnetite content can be increased and neutral buoyancy achieved by repetition of the impregnaton and neutralization steps to adjust the magnetite content to a desired level.

  5. HRTEM Imaging of Atoms at Sub-Angstrom Resolution

    SciTech Connect

    O'Keefe, Michael A.; Allard, Lawrence F.; Blom, Douglas A.

    2005-04-06

    John Cowley and his group at Arizona State University pioneered the use of transmission electron microscopy (TEM) for high-resolution imaging. Images were achieved three decades ago showing the crystal unit cell content at better than 4 Angstrom resolution. This achievement enabled researchers to pinpoint the positions of heavy atom columns within the unit cell. Lighter atoms appear as resolution is improved to sub-Angstrom levels. Currently, advanced microscopes can image the columns of the light atoms (carbon, oxygen, nitrogen) that are present in many complex structures, and even the lithium atoms present in some battery materials. Sub-Angstrom imaging, initially achieved by focal-series reconstruction of the specimen exit surface wave, will become common place for next-generation electron microscopes with CS-corrected lenses and monochromated electron beams. Resolution can be quantified in terms of peak separation and inter-peak minimum, but the limits imposed on the attainable resolution by the properties of the micro-scope specimen need to be considered. At extreme resolution the ''size'' of atoms can mean that they will not be resolved even when spaced farther apart than the resolution of the microscope.

  6. HRTEM study comparing naturally and experimentally weathered pyroxenoids

    SciTech Connect

    Banfield, J.F.; Ferruzzi, G.G.; Casey, W.H.; Westrich, H.R.

    1995-01-01

    The mineralogy and chemistry of both naturally and experimentally weathered MnSiO{sub 3} chain silicate minerals (rhodonite and pyroxmangite) were compared. In natural MnSiO{sub 3}, high-resolution transmission-electron microscope observations reveal that alteration begins at grain boundaries and planar defects parallel to the silicate chains that represent junctions between regions with different chain periodicities. Dissolution along these defects results in elongate etch pits that may be partly filled by smectite. Smectite (Ca{sub 0.3}Mn{sub 2}Zn{sub 0.4}Al{sub 0.1}Si{sub 4}O{sub 10}(OH){sub 2}) also develops in larger etches at grain boundaries. The Zn apparently released by weathering of coexisting sphalerite, may facilitate crystallization of manganese-smectite; rhodochrosite is also an initial product. X-ray diffraction patterns from highly altered materials reveal only rhodochrosite and quartz. Simplified reactions are H{sub 2}CO{sub 3}(aq) + 4 MnSiO{sub 3}(s) = Mn{sub 3}Si{sub 4}O{sub 10}(OH){sub 2}(s) + MnCO{sub 3}(s) accompanied by 3H{sub 2}CO{sub 3}(aq) + Mn{sub 3}Si{sub 4}O{sub 10}(OH){sub 2}(s) = 3 MnCO{sub 3}(s) + 4SiO{sub 2}(s) + 4H{sub 2}O. Pyroxenoid dissolution is incongruent under experimental conditions. A 3-7 nm-thick layer of amorphous silica is present at the mineral surface after {approximately}2000 h of reaction in acidic and near-neutral pH solutions that were undersaturated with respect to bulk amorphous silica. This thin layer of polymeric silica, which is absent on unreacted grains, is interpreted to have formed largely by incongruent dissolution at the mineral surface as protons in solution rapidly exchange for near-surface Mn. The layer may also contain silica readsorbed back onto the surface from solution. The net result is that silica from the pyroxenoid is redistributed directly into reaction products. Upon aging in air for a year, leached layers partially recrystallize.

  7. HRTEM study comparing naturally and experimentally weathered pyroxenoids

    NASA Astrophysics Data System (ADS)

    Banfield, Jillian F.; Ferruzzi, Giulio G.; Casey, William H.; Westrich, Henry R.

    1995-01-01

    The mineralogy and chemistry of both naturally and experimentally weathered MnSiO3 chain silicate minerals (rhodonite and pyroxmangite) were compared. In natural MnSiO3, high-resolution transmission-electron microscope observations reveal that alteration begins at grain boundaries and planar defects parallel to the silicate chains that represent junctions between regions with different chain periodicities. Dissolution along these defects results in elongate etch pits that may be partly filled by smectite. Smectite (Ca0.3Mn2.2Zn0.4Al0.1Si4O10(OH)2) also develops in larger etches at grain boundaries. The Zn apparently released by weathering of coexisting sphalerite, may facilitate crystallization of manganesesmectite; rhodochrosite is also an initial product. X-ray diffraction patterns from highly altered materials reveal only rhodochrosite and quartz. Simplified reactions are H2CO3(aq)+4MnSiO3(s)=Mn3Si4O((s)+MnCO3(s) accompanied by 3H2CO3(aq)+Mn3Si4O((s)=3MnCO3(s)+4SiO2(s)+4H2O(1) Pyroxenoid dissolution is incongruent under experimental conditions. A 3-7 nm-thic layer of amorphous silica is present at the mineral surface after ˜ 2000 h of reaction in acidic and near-neutral pH solutions that were undersaturated with respect to bulk amorphous silica. This thin layer of polymeric silica, which is absent on unreacted grains, is interpreted to have formed largely by incongruent dissolution at the mineral surface as protons in solution rapidly exchange for near-surface Mn. The layer may also contain silica readsorbed back onto the surface from solution. The net result is that silica from the pyroxenoid is redistributed directly into reaction products. Upon aging in air for a year, leached layers partially recrystallize. Both natural and experimental reactions produce secondary products by direct modification of the pyroxenoid surface. Manganese does not change oxidation state in the early stages of weathering in either setting. Unlike orthosilicates, compositional variations exert only a secondary control on chain silicate dissolution rates. For all chain silicate minerals, depolymerization of the silicate anion probably limits overall dissolution rates. As the thickness of the modified layer increases, rates may be further suppressed by diffusion (through the leached surface in the case of experimental reactions, and through secondary minerals in the case of natural weathering). The rates for wollastonite are exceptional in that the mineral dissolves more rapidly than other chain silicates and because leaching reactions are more pronounced. Natural surface modification reactions appear to be distinctive in that they occur in the presence of higher concentrations of metal cations. Clay mineral formation may be promoted by periodic drying.

  8. XRD Analyses of In{sub 0.10}Al{sub x}Ga{sub 0.90-x}N(0{<=}x{<=}0.20) Quaternary Alloys

    SciTech Connect

    Yusof, Y.; Abid, M. A.; Raof, N. H. Abd; Ng, S. S.; Hassan, H. Abu; Hassan, Z.

    2010-07-07

    We present the structural properties of quaternary In{sub 0.10}Al{sub x}Ga{sub 0.90-x}N(0{<=}x{<=}0.20) alloys grown on sapphire substrate by molecular beam epitaxy. High resolution X-ray diffraction (HR-XRD) analyses were used to investigate the phase and crystalline quality of quaternary In{sub 0.10}Al{sub x}Ga{sub 0.90-x}N. From the XRD phase analysis, it is confirmed that the In{sub 0.10}Al{sub x}Ga{sub 0.90-x}N films had wurtzite structure and without any phase separation. In addition, it is found that the Bragg angle of the (0002)In{sub 0.10}Al{sub x}Ga{sub 0.90-x}N peak gradually increases as the Al compositions increases, indicating the decrease in the lattice constant c of the In{sub 0.10}Al{sub x}Ga{sub 0.90-x}N quaternary alloys. Apart from that, the composition of In{sub 0.10}Al{sub x}Ga{sub 0.90-x}N epilayers is determined by applying the Vegard's law. Finally, the variation of the crystalline quality as a function of Al composition is investigated through the XRD rocking curve analyses.

  9. Structural and magnetic properties of nano-NiFe2O4 prepared using green nanotechnology

    NASA Astrophysics Data System (ADS)

    Yehia, M.; Labib, Sh.; Ismail, S. M.

    2014-08-01

    Nanocrystalline spinel ferrite NiFe2O4 powders were synthesized by a novel green nanotechnology derivative of sol-gel method. The effect of preparation conditions on the particle size (D) and accordingly magnetic properties was investigated using X-ray powder diffraction (XRD), Mössbauer effect spectrometer (ME) and vibrating sample magnetometer (VSM). The obtained results were compared to samples prepared using a standard ceramic method and a sol-gel technique using a citric acid route. XRD measurements reflected the spinel structure of prepared samples. The results confirmed the critical dependence of the particle size on the preparation method and heat treatment. Mössbauer effect spectroscopy measurements indicated a strong impact of the particle size on the measured spectra. A gradual decrease of the hyperfine field with decreasing D was observed. Both the saturation magnetization MS and the coercivity Hc are found to be influenced by the decrease of the particle size.

  10. Diameter Dependence of Magnetic Properties in Nanoparticle-Filled CNTs

    NASA Astrophysics Data System (ADS)

    Stojak, Kristen; Chandra, Sayan; Khurshid, Hafsa; Phan, Manh-Huong; Srikanth, Hariharan; Palmero, Ester; Vázquez, Manuel

    2014-03-01

    In past studies we showed magnetic polymer nanocomposites (MPNCs) with ferrite nanoparticle (NP) fillers to be magnetically tunable when passing microwave signals through films under the influence of an external magnetic field. We extend this study to include NP-filled multi-walled carbon nanotubes (CNTs) of various diameter (~300nm, ~100nm, ~40nm) synthesized by a catalyst-free CVD method, where the outer diameter of the CNTs is determined by a porous alumina template. These high-aspect ratio magnetic nanostructures, with tunable anisotropy and tunable saturation magnetization, are of particular interest in enhancing magnetic and microwave response in existing MPNCs. CNTs with ~ 300nm diameter have been uniformly filled with cobalt ferrite and nickel ferrite NPs (~7nm). NP-filled CNTs show an increase in blocking temperature of ~40K, as well as an increase in relaxation time, ?0. The enhancement of these properties indicates that enclosing NPs in CNTs increases interparticle interactions. The magnetic properties are also tunable by varying the diameter of CNTs. Characterization was completed with XRD, TEM and Quantum Design PPMS, with VSM and ACMS options.

  11. Magnetic Catalysis vs Magnetic Inhibition

    E-print Network

    Kenji Fukushima; Yoshimasa Hidaka

    2012-09-06

    We discuss the fate of chiral symmetry in an extremely strong magnetic field B. We investigate not only quark fluctuations but also neutral meson effects. The former would enhance the chiral-symmetry breaking at finite B according to the Magnetic Catalysis, while the latter would suppress the chiral condensate once B exceeds the scale of the hadron structure. Using a chiral model we demonstrate how neutral mesons are subject to the dimensional reduction and the low dimensionality favors the chiral-symmetric phase. We point out that this effect, the Magnetic Inhibition, can be a feasible explanation for recent lattice-QCD data indicating the decreasing behavior of the chiral-restoration temperature with increasing B.

  12. Magnetic tape

    NASA Technical Reports Server (NTRS)

    Robinson, Harriss

    1992-01-01

    The move to visualization and image processing in data systems is increasing the demand for larger and faster mass storage systems. The technology of choice is magnetic tape. This paper briefly reviews the technology past, present, and projected. A case is made for standards and the value of the standards to users.

  13. "Swinging" Magnets

    ERIC Educational Resources Information Center

    Languis, Marlin

    1975-01-01

    Presents detailed teaching plans for activities with "rubberized" magnets as well as background information and alternative teaching-learning approaches. This activity may be used to develop student skills in inferring and in observing evidence of interaction. Includes instructions for equipment construction. (BR)

  14. Magnetic switching

    SciTech Connect

    Birx, D.; Cook, E.; Hawkins, S.; Poor, S.; Reginato, L.; Schmidt, J.; Smith, M.

    1983-06-01

    The paper discusses the development program in magnetic switching which was aimed at solving the rep-rate and reliability limitations of the ATA spark gaps. The end result has been a prototype physically very similar to the present Advanced Test Accelerator (ATA) pulse power unit but vastly superior in performance. This prototype, which is easily adaptable to the existing systems, has achieved a burst rep-rate of 20 kHz and an output voltage of 500 kV. A one-on-one substitution of the existing pulse power module would result in a 100 MeV accelerator. Furthermore, the high efficiency of the magnetic pulse compression stages has allowed CW operation of the prototype at one kilohertz opening up other applications for the pulse power. Performance and design details will be described.

  15. Ferromagnetic Resonance Studies of Magnetic Recording Media

    NASA Astrophysics Data System (ADS)

    Yu, Yuwu

    1995-01-01

    Angular dependence of maximum remanence (ADMR) and/or x-ray diffraction (XRD) techniques have been used to determine particle orientation distributions for various recording media, including gamma -rm Fe_2O_3, Co- gamma-rm Fe_2O_3, CrO_2, Ba-ferrite, and MP tapes. A distribution of column directions for metal evaporated (ME) tape has been determined from transmission electron microscopy (TEM) pictures. However, the ferromagnetic resonance (FMR) results suggest a much more narrow distribution of magnetic anisotropy directions. For Ba-ferrite tapes, the distribution functions measured by ADMR are consistent with those by XRD if interparticle interactions are accounted for. The predetermined distribution function has been used to fit FMR spectra for the above tapes. Landau-Lifshitz damping constants have been measured with high accuracy for particulate recording media. An excellent correlation has been found between the damping constants and the switching constants for these media. The results suggest that the FMR technique may be useful in predicting the switching speed of particulate recording media. The FMR technique is also useful in looking for methods of increasing the damping constant of recording media. Possible methods of increasing the switching speed of Ba-ferrite media have been studied. The reduction of Ba-ferrite particles in a hydrogen atmosphere increases the damping constant significantly. It is predicted that reduced Ba-ferrite probably switches faster than ordinary Ba-ferrite. Qualitative discussions on the origin of damping for various recording media have been presented within the framework of magnon relaxation theory. The dependence of the damping constant on magnetic properties, such as particle orientation, media coercivity, and particle interactions are also discussed.

  16. Magnetic Reconnection

    SciTech Connect

    Masaaki Yamada, Russell Kulsrud and Hantao Ji

    2009-09-17

    We review the fundamental physics of magnetic reconnection in laboratory and space plasmas, by discussing results from theory, numerical simulations, observations from space satellites, and the recent results from laboratory plasma experiments. After a brief review of the well-known early work, we discuss representative recent experimental and theoretical work and attempt to interpret the essence of significant modern findings. In the area of local reconnection physics, many significant findings have been made with regard to two- uid physics and are related to the cause of fast reconnection. Profiles of the neutral sheet, Hall currents, and the effects of guide field, collisions, and micro-turbulence are discussed to understand the fundamental processes in a local reconnection layer both in space and laboratory plasmas. While the understanding of the global reconnection dynamics is less developed, notable findings have been made on this issue through detailed documentation of magnetic self-organization phenomena in fusion plasmas. Application of magnetic reconnection physics to astrophysical plasmas is also brie y discussed.

  17. Polymer nanocomposites exhibiting magnetically tunable microwave properties.

    PubMed

    Stojak, K; Pal, S; Srikanth, H; Morales, C; Dewdney, J; Weller, T; Wang, J

    2011-04-01

    Polymer nanocomposites (PNCs) have been synthesized using Rogers polymer and CoFe?O? nanoparticles (CFO NPs). X-ray diffraction (XRD) confirms the inverse spinel crystal structure of CFO NPs and transmission electron microscopy (TEM) images show the uniform dispersion of nanoparticles (10 nm ± 1) into the polymer matrix. Magnetic measurements indicate superparamagnetic response near room temperature for all PNCs. A blocking temperature T(B)~298 K was observed and does not vary for different loading fractions of CFO NPs for the PNCs. The saturation magnetization (M(s)) was found to be 11 emu g?¹ for 30 wt% CFO, increasing to 32 emu g?¹ for the 80 wt% CFO loaded PNC. A large value of coercivity (H(c) = 19 kOe) is also observed at 10 K and is not affected by varying CFO loading. Microwave measurements show significant absorption in the 80 wt% CFO loading PNC and the quality factor shows a strong enhancement with applied magnetic field. PMID:21343635

  18. Magnetic Measurement and Magnet Tutorial, Part 3

    SciTech Connect

    Tanabe, Jack

    2003-07-15

    Magnetic measurements, like magnet design, is a broad subject. It is the intention of this lecture to cover only a small part of the field, regarding the characterization of the line integral field quality of multipole magnets (dipoles, quadrupoles and sextupoles) using compensated rotating coils. Other areas which are not covered are magnet mapping, AC measurements and sweeping wire measurements.

  19. The effects of high magnetic field on the morphology and microwave electromagnetic properties of MnO{sub 2} powder

    SciTech Connect

    Jia Zhang; Duan Yuping; Li Shuqing; Li Xiaogang; Liu Shunhua

    2010-07-15

    MnO{sub 2} with a sea urchin-like ball chain shape was first synthesized in a high magnetic field via a simple chemical process, and a mechanism for the formation of this grain shape was discussed. The as-synthesized samples were characterized by XRD, SEM, TEM, and vector network analysis. The dielectric constant and the loss tangent clearly decreased under a magnetic field. The magnetic loss tangent and the imaginary part of the magnetic permeability increased substantially. Furthermore, the theoretically calculated values of reflection loss showed that the absorption peaks shifted to a higher frequency with increases in the magnetic field strength. - Graphical abstract: MnO{sub 2} with a sea urchin-like ball chain shape is first synthesized in a high magnetic field via a simple hydrothermal route.

  20. Effect of CoSi2 buffer layer on structure and magnetic properties of Co films grown on Si (001) substrate

    NASA Astrophysics Data System (ADS)

    Hu, Bo; He, Wei; Ye, Jun; Tang, Jin; Syed Sheraz, Ahmad; Zhang, Xiang-Qun; Cheng, Zhao-Hua

    2015-01-01

    Buffer layer provides an opportunity to enhance the quality of ultrathin magnetic films. In this paper, Co films with different thickness of CoSi2 buffer layers were grown on Si (001) substrates. In order to investigate morphology, structure, and magnetic properties of films, scanning tunneling microscope (STM), low energy electron diffraction (LEED), high resolution transmission electron microscopy (HRTEM), and surface magneto-optical Kerr effect (SMOKE) were used. The results show that the crystal quality and magnetic anisotropies of the Co films are strongly affected by the thickness of CoSi2 buffer layers. Few CoSi2 monolayers can prevent the interdiffusion of Si substrate and Co film and enhance the Co film quality. Furthermore, the in-plane magnetic anisotropy of Co film with optimal buffer layer shows four-fold symmetry and exhibits the two-jumps of magnetization reversal process, which is the typical phenomenon in cubic (001) films. Project supported by the National Basic Research Program of China (Grant Nos. 2011CB921801 and 2012CB933102), the National Natural Science Foundation of China (Grant Nos. 11374350, 11034004, 11274361, and 11274033), and the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20131102130005).

  1. The effect of varying the capping agent of magnetic/luminescent Fe3O4-InP/ZnSe core-shell nanocomposite

    NASA Astrophysics Data System (ADS)

    Paulsen, Zuraan; Onani, Martin O.; Allard, Garvin R. J.; Kiplagat, Ayabei; Okil, Joseph O.; Dejene, Francis B.; Mahanga, Geoffrey M.

    2016-01-01

    Magnetic-luminescent nanoparticles have shown great promise in various biomedical applications namely: contrast agents for magnetic resonance imaging, multifunctional drug carrier system, magnetic separation of cells, cell tracking, immunoassay, and magnetic bioseparation. This experiment describes the synthesis of a nanocomposite material, which is composed of an iron oxide (Fe3O4) superparamagnetic core and an indium phosphide/zinc selenide (InP/ZnSe) quantum dot shell. The magnetic nanoparticles (MNP's) and quantum dots (QD's) were synthesized separately before allowing them to conjugate. The MNP's were functionalized with a thiol-group allowing the QD shell to bind to the surface of the MNP by the formation of a thiol-metal bond. The nanocomposite was capped with 3-mercaptopropionic acid, oleylamine, ?-cyclodextrin and their influence on the photoluminescence investigated. The synthesized nanocomposite was characterized with high- resolution transmission electron microscopy (HR-TEM), energy-dispersive spectroscopy (EDS), selective electron area diffraction (SAED), scanning electron microscopy (SEM), superconducting quantum interference device (SQUID), and photoluminescence. These techniques yielded particle size, morphology, dispersion, and chemical composition including luminescence and florescence.

  2. One-step synthesis of magnetic chitosan polymer composite films

    NASA Astrophysics Data System (ADS)

    Cesano, Federico; Fenoglio, Gaia; Carlos, Luciano; Nisticò, Roberto

    2015-08-01

    In this study, a magnetic iron oxide-chitosan composite film is synthesized by one-step method and thoroughly investigated in order to better understand its inorganic/organic properties. A deep physico-chemical characterization of the magnetic films has been performed. In particular, the material composition was evaluated by means of XRD and ATR-FTIR spectroscopy, whereas the thermal stability and the subsequent inorganic phase transitions involving iron oxide species were followed by TGA analyses carried out at different experimental conditions (i.e. inert and oxidative atmosphere). The magnetic properties of the films were tested at the bulk and at the surface level, performing respectively magnetization hysteresis curve and magnetic force microscopy (MFM) surface mapping. Results indicate that the synthesized material can be prepared through a very simple synthetic procedure and suggests that it can be successfully applied for instance to environmental applications, such as the adsorption of contaminants from solid and liquid media thanks to its pronounced magnetic properties, which favour its recover.

  3. Template-assisted fabrication of magnetically responsive hollow titania capsules.

    PubMed

    Agrawal, Mukesh; Gupta, Smrati; Pich, Andrij; Zafeiropoulos, Nikolaos E; Rubio-Retama, Jorge; Jehnichen, Dieter; Stamm, Manfred

    2010-11-16

    This study reports on the fabrication of magnetically responsive hollow titania capsules by confining the superparamagnetic Fe(3)O(4) nanoparticles within a hollow and porous titania (TiO(2)) shell. The employed protocol involves precipitation of titania shell on the magnetite (Fe(3)O(4)) encapsulated polystyrene beads followed by the calcination of resulting composite particles at elevated temperature. Scanning electron microscopy and transmission electron microscopy reveal the presence of a thick, complete but irregular titania shell on the magnetic polystyrene beads after the templating process. Electron energy loss mapping image analysis has been employed to investigate the spatial distribution of titania and magnetite phases of magnetic hollow titania capsules (MHTCs). Magnetic characterization indicates that both titania-coated magnetic polystyrene beads (TMPBs) and MHTCs are superparamagnetic in nature with the saturated magnetizations of 5.6 and 8.1 emu/g, respectively. X-ray diffraction (XRD) analysis reveals that titania shell of these capsules is composed of photoactive anatase phase. Nitrogen adsorption-desorption analysis has been employed to estimate the specific surface area and the average pore diameter of the fabricated hollow structures. Photocatalytic activity of the fabricated MHTCs for the photodegradation of rhodamine 6G dye has been demonstrated and compared with that of bulk titania nanoparticles. PMID:20949923

  4. Effects of boron composition on tunneling magnetoresistance ratio and microstructure of CoFeB/MgO/CoFeB pseudo-spin-valve magnetic tunnel junctions

    SciTech Connect

    Kodzuka, M.; Ohkubo, T.; Hono, K.; Ikeda, S.; Ohno, H.; Gan, H. D.

    2012-02-15

    The effect of B concentration on the tunneling magnetoresistance (TMR) of (Co{sub 25}Fe{sub 75}){sub 100-x}B{sub x}/MgO/(Co{sub 25}Fe{sub 75}){sub 100-x}B{sub x} (x = 22 and 33) pseudo-spin-valve (P-SV) magnetic tunnel junctions (MTJs) was investigated. The TMR ratios for optimally annealed MTJs with x = 22 and 33 were 340% and 170%, respectively, at room temperature. High resolution transmission electron microscopy (HRTEM) observation showed a weaker (001) texture in the MgO barrier in the MTJ with x = 33. The bottom electrode was not fully crystallized even with a considerable amount of B in the (Co{sub 25}Fe{sub 75}){sub 67}B{sub 33}, while good epitaxy was observed between (001) textured MgO and (Co{sub 25}Fe{sub 75}){sub 78}B{sub 22} electrodes.

  5. Highly c-axis oriented ZnO:Ni thin film nanostructure by RF magnetron sputtering: Structural, morphological and magnetic studies

    NASA Astrophysics Data System (ADS)

    Siddheswaran, R.; Savková, Jarmila; Medlín, Rostislav; O?enášek, Jan; Životský, Ond?ej; Novák, Petr; Šutta, Pavol

    2014-10-01

    Nickel doped zinc oxide (ZnO:Ni) thin films with different Ni concentrations were deposited on silicon substrates at 400 °C by reactive magnetron sputtering using a mixture of Ar and O2 gases. The X-ray diffraction and azimuthal patterns of the ZnO:Ni were carried out, and the quality of the strong preferred orientation of crystalline columns in the direction [0 0 1] perpendicular to the substrate surface were analysed. The grain size, distribution, and homogeneity of the thin film surfaces were studied by FE-SEM. The EDX and mapping confirmed that the Ni is incorporated into ZnO uniformly. The microstructure of the textured columns was analysed by TEM and HRTEM analyses. The average thickness and length of the columns were found to be about 50 nm and 600 nm, respectively. The rise of ferromagnetism by the influence of Ni content was studied by VSM magnetic studies at room temperature.

  6. Protection of NdFeB magnets by corrosion resistance phytic acid conversion film

    NASA Astrophysics Data System (ADS)

    Nan, Haiyang; Zhu, Liqun; Liu, Huicong; Li, Weiping

    2015-11-01

    Phytic acid conversion film was prepared on NdFeB magnets by dipping the NdFeB into phytic acid solution. The morphology, composition, structure and corrosion resistance of the film were systematically investigated. The results showed that the phytic acid film was effective in improving the corrosion resistance of NdFeB magnets. XRD, TEM and FT-IR analyses revealed that the film was amorphous and had a strong peak of phosphate radical (PO43-). The formation mechanism of the film was also explored by XPS and the potential of zero charge (Epzc) measurement at the solution-metal interface.

  7. Magnetic properties of Ni/NiO nanocomposites synthesized by one step solution combustion method

    NASA Astrophysics Data System (ADS)

    Ganeshchandra Prabhu, V.; Shajira, P. S.; Lakshmi, N.; Junaid Bushiri, M.

    2015-12-01

    Ni/NiO nanocomposites were synthesized using solution combustion method and characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX) and carbon, hydrogen, nitrogen (CHN) analyser. The Ni or NiO content in Ni/NiO nanocomposites vary with the quantity of HNO3 used for the synthesis. Magnetic coercivity (Hc) of Ni/NiO nanocomposites is found to be 413 Oe which can be used in magnetic applications. A feeble exchange bias of 7 Oe is seen from the NiO rich Ni/NiO.

  8. An X-ray diffraction (XRD) and Fourier transform infrared spectroscopic (FT-IR) investigation of the long-term effect on the solidification/stabilization (S/S) of arsenic(V) in Portland cement type-V.

    PubMed

    Mollah, Mohammad Y A; Kesmez, Mehmet; Cocke, David L

    2004-06-01

    The long-term effects on solidification/stabilization (S/S) of As5+-bearing oxyanions (AsO4(3)-) in Portland cement type-V (OPC) have been investigated by X-ray diffraction (XRD) and Fourier transform infrared spectroscopic (FT-IR) techniques. The results of this study confirm our previous results that the early hydration of cement is inhibited by the presence of AsO4(3)-, and that the inhibition is mainly caused by the formation of highly insoluble Ca3(AsO4)2 on the surface of hydrating cement particles. Arsenate analog of ettringite [Ca6(Al2O6)(SO4)3 x 32H2O] was identified in the early stages of hydration of pure Portland cement and As(V)-treated Portland cement [OPC-As(V)], but not in 10-year-old similar samples. The XRD and FT-IR results indicated interactions of oxyanions and cement particles to produce minor quantities of As5+-bearing compounds in fresh as well as in 10-year-old samples. New As5+-bearing phases, NaCaAsO4 x 7.5H2O and Ca5(AsO4)3OH were identified in the 10-year-old OPC-As(V) samples by XRD analyses. Based on these results it is concluded that Portland cement may be considered as a potential matrix to immobilize As5+-bearing wastes. PMID:15144793

  9. Structural and magnetic characterization of as-prepared and annealed FeCoCu nanowire arrays in ordered anodic aluminum oxide templates

    SciTech Connect

    Rodríguez-González, B.; Bran, C.; Warnatz, T.; Vazquez, M.; Rivas, J.

    2014-04-07

    Herein, we report on the preparation, structure, and magnetic characterization of FeCoCu nanowire arrays grown by DC electrodeposition inside self-assembled ordered nanopores of anodic aluminum oxide templates. A systematic study of their structure has been performed both in as-prepared samples and after annealing in the temperature range up to 800?°C, although particular attention has been paid to annealing at 700?°C after which maximum magnetic hardening is achieved. The obtained nanowires have a diameter of 40?nm and their Fe{sub 0.28}Co{sub 0.67}Cu{sub 0.05} composition was confirmed by energy dispersive X-ray spectroscopy (EDS). Focused ion-beam lamellas of two samples (as-prepared and annealed at 700?°C) were prepared for their imaging in the high-resolution transmission electron microscopy (HRTEM) perpendicularly to the electron beam, where the obtained EDS compositional mappings show a homogeneous distribution of the elements. X-ray diffraction analysis, and selected area electron diffraction (SAED) patterns confirm that nanowires exhibit a bcc cubic structure (space group Im-3m). In addition, bright-dark field images show that the nanowires have a polycrystalline structure that remains essentially the same after annealing, but some modifications were observed: (i) an overall increase and sharpening of recrystallized grains, and (ii) an apparent shrinkage of the nanowires diameter. Obtained SAED patterns also show strong textured components with determined <111> and <112> crystalline directions parallel to the wires growth direction. The presence of both directions was also confirmed in the HRTEM images doing Fourier transform analyses. Magnetic measurements show strong magnetic anisotropy with magnetization easy axis parallel to the nanowires in as-prepared and annealed samples. The magnetic properties are tuned by suitable thermal treatments so that, maximum enhanced coercivity (?2.7 kOe) and normalized remanence (?0.91 Ms) values are achieved after annealing at temperature of 700?°C. The contribution of the changes in the crystalline structure, induced by the heat treatment, to the magnetic hardening of the FeCoCu nanowires is discussed.

  10. Structural and magnetic characterization of as-prepared and annealed FeCoCu nanowire arrays in ordered anodic aluminum oxide templates

    NASA Astrophysics Data System (ADS)

    Rodríguez-González, B.; Bran, C.; Warnatz, T.; Rivas, J.; Vazquez, M.

    2014-04-01

    Herein, we report on the preparation, structure, and magnetic characterization of FeCoCu nanowire arrays grown by DC electrodeposition inside self-assembled ordered nanopores of anodic aluminum oxide templates. A systematic study of their structure has been performed both in as-prepared samples and after annealing in the temperature range up to 800 °C, although particular attention has been paid to annealing at 700 °C after which maximum magnetic hardening is achieved. The obtained nanowires have a diameter of 40 nm and their Fe0.28Co0.67Cu0.05 composition was confirmed by energy dispersive X-ray spectroscopy (EDS). Focused ion-beam lamellas of two samples (as-prepared and annealed at 700 °C) were prepared for their imaging in the high-resolution transmission electron microscopy (HRTEM) perpendicularly to the electron beam, where the obtained EDS compositional mappings show a homogeneous distribution of the elements. X-ray diffraction analysis, and selected area electron diffraction (SAED) patterns confirm that nanowires exhibit a bcc cubic structure (space group Im-3m). In addition, bright-dark field images show that the nanowires have a polycrystalline structure that remains essentially the same after annealing, but some modifications were observed: (i) an overall increase and sharpening of recrystallized grains, and (ii) an apparent shrinkage of the nanowires diameter. Obtained SAED patterns also show strong textured components with determined ?111? and ?112? crystalline directions parallel to the wires growth direction. The presence of both directions was also confirmed in the HRTEM images doing Fourier transform analyses. Magnetic measurements show strong magnetic anisotropy with magnetization easy axis parallel to the nanowires in as-prepared and annealed samples. The magnetic properties are tuned by suitable thermal treatments so that, maximum enhanced coercivity (˜2.7 kOe) and normalized remanence (˜0.91 Ms) values are achieved after annealing at temperature of 700 °C. The contribution of the changes in the crystalline structure, induced by the heat treatment, to the magnetic hardening of the FeCoCu nanowires is discussed.

  11. Magnetic Reconnection in Astrophysical and

    E-print Network

    Magnetic Reconnection in Astrophysical and Laboratory Plasmas Ellen G. Zweibel1 and Masaaki Yamada2 astrophysics, magnetic fields, magnetic reconnection Abstract Magnetic reconnection is a topological rearrangement of magnetic field that converts magnetic energy to plasma energy. Astrophysical flares, from

  12. What makes some materials Magnets are magnetic dipoles

    E-print Network

    Bertulani, Carlos A. - Department of Physics and Astronomy, Texas A&M University

    Magnetism What makes some materials magnetic? Magnets are magnetic dipoles - have north and south pole If we break a magnet we still have magnetic dipoles Magnetic monopoles do not exist #12;Magnetism of Earth Earth acts as huge bar magnet Geomagnetic pole at angle of 11.5 degrees from rotational axis North

  13. Structural and magnetic properties of Vanadium Doped M- Type Barium Hexaferrite (BaFe12-xVxO19)

    NASA Astrophysics Data System (ADS)

    Awadallah, Ahmad; Mahmood, Sami H.; Maswadeh, Yazan; Bsoul, Ibrahim; Aloqaily, Aynour

    2015-10-01

    Precursor powders of barium hexaferrite doped with vanadium, BaFe12-xVxO19 with (x = 0.1, 0.2, 0.3, 0.4, 0.5), were prepared using the ball milling technique and then sintered at different temperatures for 2 h. The structural properties of the prepared samples were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), while the magnetic properties were examined by the vibrating sample magnetometry (VSM). XRD and SEM studies of the samples sintered at 1100° C indicated the presence of Ba3V2O8 and ?-Fe2O3 non-magnetic oxide phases in addition to BaM hexaferrite phase. The fractions of the nonmagnetic oxide phases were found to increase with increasing x, and sintering the samples at temperatures higher than 1100° C was found to reduce the amounts of these non-magnetic phases only slightly. However, the addition of barium in excess of the stoichiometric ratio was found to remove the ?-Fe2O3 oxide, and improve the saturation magnetization of the samples significantly. In addition, washing these samples with HCl was found to improve the saturation magnetization further. The effect of sintering the samples at higher temperatures was also found to reduce the coercivity due to growth of the particle size. However, the coercivity of all samples remained high enough for potential permanent magnet and magnetic recording applications.

  14. Magnetic properties of hematite (?-Fe2O3) nanoparticles prepared by hydrothermal synthesis method

    NASA Astrophysics Data System (ADS)

    Tadic, Marin; Panjan, Matjaz; Damnjanovic, Vesna; Milosevic, Irena

    2014-11-01

    Hematite (?-Fe2O3) nanoparticles are successfully synthesized by using the hydrothermal synthesis method. An X-ray powder diffraction (XRPD) of the sample shows formation of the nanocrystalline ?-Fe2O3 phase. A transmission electron microscopy (TEM) measurements show spherical morphology of the hematite nanoparticles and narrow size distribution. An average hematite nanoparticle size is estimated to be about 8 nm by TEM and XRD. Magnetic properties were measured using a superconducting quantum interference device (SQUID) magnetometry. Investigation of the magnetic properties of hematite nanoparticles showed a divergence between field-cooled (FC) and zero-field-cooled (ZFC) magnetization curves below Tirr = 103 K (irreversibility temperature). The ZFC magnetization curve showed maximum at TB = 52 K (blocking temperature). The sample did not exhibit the Morin transition. The M(H) (magnetization versus magnetic field) dependence at 300 K showed properties of superparamagnetic iron oxide nanoparticles (SPION). The M(H) data were successfully fitted by the Langevin function and magnetic moment ?p = 657 ?B and diameter d = 8.1 nm were determined. Furthermore, magnetic measurements showed high magnetization at room temperature (MS = 3.98 emu/g), which is desirable for application in spintronics and biomedicine. Core-shell structure of the nanoparticles was used to describe high magnetization of the hematite nanoparticles.

  15. Synthesis of magnetic multicomponent nanoparticles CuxNi1-xFe2O4

    NASA Astrophysics Data System (ADS)

    Bingölbali, A.; Do?an, N.; Ye?il, Z.; Asiltürk, M.

    2015-01-01

    Magnetic nanoparticles (MNPs) are of great importance in many biomedical applications, such as drug delivery, hyperthermia, and magnetic resonance imaging (MRI) contrast enhancement. To build the most effective magnetic nanoparticle systems for various biomedical applications, characteristics of particle, including size, surface chemistry, magnetic properties, and toxicity have to be fully investigated. In this work, the effects of some production methods of the magnetic nanoparticles for the bio-medical applications are discussed. In this study, multicomponents of CuxNi1-xFe2O4 nanoparticles (where x=0, 0.6, and 1) were prepared by the hydrothermal synthesis method. In addition, X-ray powder diffractometry (XRD), scanning electron microscopy (SEM), and a vibrating scanning magnetometer (VSM) were used to characterize the structural, morphological and magnetic properties of the nanoparticles. The particle sizes of the samples were measured by Malvern Instruments Zeta Sizer Nano-ZS instrument. The data were recorded under magnetic fields for different ratios of CuxNi1-xFe2O4 nanoparticles. The temperature dependence of field cooled (FC) magnetization of the CuxNi1-xFe2O4 samples has been shown in this work. Magnetizations change with decreasing the dopant value of Cu. The magnetic phase transition was observed for CuxNi1-xFe2O4 nanoparticles.

  16. On the mineral core of ferritin-like proteins: structural and magnetic characterization.

    PubMed

    García-Prieto, A; Alonso, J; Muñoz, D; Marcano, L; Abad Díaz de Cerio, A; Fernández de Luis, R; Orue, I; Mathon, O; Muela, A; Fdez-Gubieda, M L

    2015-12-23

    It is generally accepted that the mineral core synthesized by ferritin-like proteins consists of a ferric oxy-hydroxide mineral similar to ferrihydrite in the case of horse spleen ferritin (HoSF) and an oxy-hydroxide-phosphate phase in plant and prokaryotic ferritins. The structure reflects a dynamic process of deposition and dissolution, influenced by different biological, chemical and physical variables. In this work we shed light on this matter by combining a structural (High Resolution Transmission Electron Microscopy (HRTEM) and Fe K-edge X-ray Absorption Spectroscopy (XAS)) and a magnetic study of the mineral core biomineralized by horse spleen ferritin (HoSF) and three prokaryotic ferritin-like proteins: bacterial ferritin (FtnA) and bacterioferritin (Bfr) from Escherichia coli and archaeal ferritin (PfFtn) from Pyrococcus furiosus. The prokaryotic ferritin-like proteins have been studied under native conditions and inside the cells for the sake of preserving their natural attributes. They share with HoSF a nanocrystalline structure rather than an amorphous one as has been frequently reported. However, the presence of phosphorus changes drastically the short-range order and magnetic response of the prokaryotic cores with respect to HoSF. The superparamagnetism observed in HoSF is absent in the prokaryotic proteins, which show a pure atomic-like paramagnetic behaviour attributed to phosphorus breaking the Fe-Fe exchange interaction. PMID:26666195

  17. Magnetic properties of nanoscale crystalline maghemite obtained by a new synthetic route

    NASA Astrophysics Data System (ADS)

    Mercante, L. A.; Melo, W. W. M.; Granada, M.; Troiani, H. E.; Macedo, W. A. A.; Ardison, J. D.; Vaz, M. G. F.; Novak, M. A.

    2012-09-01

    In this work we describe the synthesis and characterization of maghemite nanoparticles obtained by a new synthetic route. The material was synthesized using triethylamine as a coprecipitation agent in the presence of the organic ligand N,N?-bis(3,5-di-tert-butyl-catechol)-2,4-diaminotoluene (LCH3). Mössbauer spectrum at 4 K shows typical hyperfine parameters of maghemite and Transmission Electron Microscopy images reveal that the nanoparticles have a mean diameter of 3.9 nm and a narrow size distribution. AC magnetic susceptibility in zero field presents an Arrhenius behavior with unreasonable relaxation parameters due to the strong influence of dipolar interaction. In contrast when the measurements are performed in a 1 kOe field, the effect of dipolar interactions becomes negligible and the obtained parameters are in good agreement with the static magnetic properties. The dynamic energy barrier obtained from the AC susceptibility results is larger than the expected from the average size observed by HRTEM results, evidencing the strong influence of the surface contribution to the anisotropy.

  18. Structure determination of CoPt nanoparticles: Chemical ordering and its effect on magnetic properties

    NASA Astrophysics Data System (ADS)

    Blanc, Nils; Bardotti, Laurent; Hillenkamp, Matthias; Tamion, Alexandre; Tournus, Florent; Tuaillon-Combes, Juliette; Dupuis, Veronique; Bonet, Edgar; Tolentino, Helio; Ramos, Aline; de Santis, Maurizio; Ohresser, Philippe; Epicier, Thierry

    2009-03-01

    Due to the huge magnetocrystalline anisotropy of bulk CoPt crystallized in the L10 phase, CoPt nanoparticles have been widely studied during the last decade. In order to determine the intrinsic magnetic properties of CoPt clusters, we synthesize benchmark samples: 3 nm diameter CoPt clusters, pre-formed in the gas phase, are embedded in an amorphous carbon matrix under UHV conditions. The transition from the chemically disordered A1 to the ordered L10 phase is then obtained by annealing. Chemical ordering has clearly been evidenced by different techniques (HRTEM, GIXRD). In the case of nanoparticles, this phase transition goes with a magnetic anisotropy increase much lower than for the bulk. Besides, XMCD measurements have revealed a ?L/?S increase for Co and Pt atoms and a strong ?S enhancement for Co upon L10 ordering. F. Tournus et al. Phys. Rev. B 77, 144411 (2008) Thanks are due to the CLYM (Centre Lyonnais de Microscope) for the access to the tranmission electron microscope

  19. Highly selective adsorption of lead ions by water-dispersible magnetic chitosan/graphene oxide composites.

    PubMed

    Fan, Lulu; Luo, Chuannan; Sun, Min; Li, Xiangjun; Qiu, Huamin

    2013-03-01

    Magnetic chitosan/graphene oxide (MCGO) materials were fabricated through a facile and fast process and their application as excellent adsorbents for metal ions was also demonstrated. The characteristics results of FTIR, SEM, TEM, VSM and XRD showed that MCGO was successfully prepared. The SEM and TEM revealed that magnetic chitosan had been assembled on the surface of graphene oxide layers with a high density. The XRD and VSM indicated the MCGO had enough magnetic response to meet the need of magnetic separation. The magnetic chitosan grafted with graphene oxide sheets showed an increased surface area. The MCGO was used as sorbents for the removal of Pb(II) ions from large volumes of aqueous solutions. The effects of pH, contact time, and concentration on Pb(II) ions sorption were investigated. The results indicated that Pb(II) ions sorption on MCGO was strongly dependent on pH. The abundant functional groups on the surfaces of MCGO played an important role on Pb(II) sorption. Equilibrium studies showed that the data of Pb(II) adsorption followed the Langmuir model. The maximum adsorption capacity for Pb(II) was estimated to be 76.94 mg/g. The MCGO was stable and easily recovered. PMID:23261576

  20. Poly-l-lysine-coated magnetic nanoparticles as intracellular actuators for neural guidance

    PubMed Central

    Riggio, Cristina; Calatayud, Maria Pilar; Hoskins, Clare; Pinkernelle, Josephine; Sanz, Beatriz; Torres, Teobaldo Enrique; Ibarra, Manuel Ricardo; Wang, Lijun; Keilhoff, Gerburg; Goya, Gerardo Fabian; Raffa, Vittoria; Cuschieri, Alfred

    2012-01-01

    Purpose It has been proposed in the literature that Fe3O4 magnetic nanoparticles (MNPs) could be exploited to enhance or accelerate nerve regeneration and to provide guidance for regenerating axons. MNPs could create mechanical tension that stimulates the growth and elongation of axons. Particles suitable for this purpose should possess (1) high saturation magnetization, (2) a negligible cytotoxic profile, and (3) a high capacity to magnetize mammalian cells. Unfortunately, the materials currently available on the market do not satisfy these criteria; therefore, this work attempts to overcome these deficiencies. Methods Magnetite particles were synthesized by an oxidative hydrolysis method and characterized based on their external morphology and size distribution (high-resolution transmission electron microscopy [HR-TEM]) as well as their colloidal (Z potential) and magnetic properties (Superconducting QUantum Interference Devices [SQUID]). Cell viability was assessed via Trypan blue dye exclusion assay, cell doubling time, and MTT cell proliferation assay and reactive oxygen species production. Particle uptake was monitored via Prussian blue staining, intracellular iron content quantification via a ferrozine-based assay, and direct visualization by dual-beam (focused ion beam/scanning electron microscopy [FIB/SEM]) analysis. Experiments were performed on human neuroblastoma SH-SY5Y cell line and primary Schwann cell cultures of the peripheral nervous system. Results This paper reports on the synthesis and characterization of polymer-coated magnetic Fe3O4 nanoparticles with an average diameter of 73 ± 6 nm that are designed as magnetic actuators for neural guidance. The cells were able to incorporate quantities of iron up to 2 pg/cell. The intracellular distribution of MNPs obtained by optical and electronic microscopy showed large structures of MNPs crossing the cell membrane into the cytoplasm, thus rendering them suitable for magnetic manipulation by external magnetic fields. Specifically, migration experiments under external magnetic fields confirmed that these MNPs can effectively actuate the cells, thus inducing measurable migration towards predefined directions more effectively than commercial nanoparticles (fluidMAG-ARA supplied by Chemicell). There were no observable toxic effects from MNPs on cell viability for working concentrations of 10 ?g/mL (EC25 of 20.8 ?g/mL, compared to 12 ?g/mL in fluidMAG-ARA). Cell proliferation assays performed with primary cell cultures of the peripheral nervous system confirmed moderate cytotoxicity (EC25 of 10.35 ?g/mL). Conclusion These results indicate that loading neural cells with the proposed MNPs is likely to be an effective strategy for promoting non-invasive neural regeneration through cell magnetic actuation. PMID:22811603

  1. Biomimetic magnetic silk scaffolds.

    PubMed

    Samal, Sangram K; Dash, Mamoni; Shelyakova, Tatiana; Declercq, Heidi A; Uhlarz, Marc; Bañobre-López, Manuel; Dubruel, Peter; Cornelissen, Maria; Herrmannsdörfer, Thomas; Rivas, Jose; Padeletti, Giuseppina; De Smedt, Stefaan; Braeckmans, Kevin; Kaplan, David L; Dediu, V Alek

    2015-03-25

    Magnetic silk fibroin protein (SFP) scaffolds integrating magnetic materials and featuring magnetic gradients were prepared for potential utility in magnetic-field assisted tissue engineering. Magnetic nanoparticles (MNPs) were introduced into SFP scaffolds via dip-coating methods, resulting in magnetic SFP scaffolds with different strengths of magnetization. Magnetic SFP scaffolds showed excellent hyperthermia properties achieving temperature increases up to 8 °C in about 100 s. The scaffolds were not toxic to osteogenic cells and improved cell adhesion and proliferation. These findings suggest that tailored magnetized silk-based biomaterials can be engineered with interesting features for biomaterials and tissue-engineering applications. PMID:25734962

  2. Electrically Tunable Magnetism in Magnetic Topological Insulators

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Lian, Biao; Zhang, Shou-Cheng

    2015-07-01

    The external controllability of the magnetic properties in topological insulators would be important both for fundamental and practical interests. Here we predict the electric-field control of ferromagnetism in a thin film of insulating magnetic topological insulators. The decrease of band inversion by the application of electric fields results in a reduction of magnetic susceptibility, and hence in the modification of magnetism. Remarkably, the electric field could even induce the magnetic quantum phase transition from ferromagnetism to paramagnetism. We further propose a transistor device in which the dissipationless charge transport of chiral edge states is controlled by an electric field. In particular, the field-controlled ferromagnetism in a magnetic topological insulator can be used for voltage based writing of magnetic random access memories in magnetic tunnel junctions. The simultaneous electrical control of magnetic order and chiral edge transport in such devices may lead to electronic and spintronic applications for topological insulators.

  3. Electrically Tunable Magnetism in Magnetic Topological Insulators.

    PubMed

    Wang, Jing; Lian, Biao; Zhang, Shou-Cheng

    2015-07-17

    The external controllability of the magnetic properties in topological insulators would be important both for fundamental and practical interests. Here we predict the electric-field control of ferromagnetism in a thin film of insulating magnetic topological insulators. The decrease of band inversion by the application of electric fields results in a reduction of magnetic susceptibility, and hence in the modification of magnetism. Remarkably, the electric field could even induce the magnetic quantum phase transition from ferromagnetism to paramagnetism. We further propose a transistor device in which the dissipationless charge transport of chiral edge states is controlled by an electric field. In particular, the field-controlled ferromagnetism in a magnetic topological insulator can be used for voltage based writing of magnetic random access memories in magnetic tunnel junctions. The simultaneous electrical control of magnetic order and chiral edge transport in such devices may lead to electronic and spintronic applications for topological insulators. PMID:26230818

  4. Thin Magnetically Soft Wires for Magnetic Microsensors

    PubMed Central

    Zhukova, Valentina; Ipatov, Mihail; Zhukov, Arcady

    2009-01-01

    Recent advances in technology involving magnetic materials require development of novel advanced magnetic materials with improved magnetic and magneto-transport properties and with reduced dimensionality. Therefore magnetic materials with outstanding magnetic characteristics and reduced dimensionality have recently gained much attention. Among these magnetic materials a family of thin wires with reduced geometrical dimensions (of order of 1–30 ?m in diameter) have gained importance within the last few years. These thin wires combine excellent soft magnetic properties (with coercivities up to 4 A/m) with attractive magneto-transport properties (Giant Magneto-impedance effect, GMI, Giant Magneto-resistance effect, GMR) and an unusual re-magnetization process in positive magnetostriction compositions exhibiting quite fast domain wall propagation. In this paper we overview the magnetic and magneto-transport properties of these microwires that make them suitable for microsensor applications. PMID:22291562

  5. Permanent magnet assembly

    DOEpatents

    Chell, Jeremy; Zimm, Carl B.

    2006-12-12

    A permanent magnet assembly is disclosed that is adapted to provide a magnetic field across an arc-shaped gap. Such a permanent magnet assembly can be used, for example, to provide a time-varying magnetic field to an annular region for use in a magnetic refrigerator.

  6. Magnet innovations for linacs

    SciTech Connect

    Halbach, K.

    1986-06-01

    It is possible to produce large magnetic fields at the aperture of permanent magnet quadrupoles, even when the magnetic aperture is very small. That, combined with their compactness, makes permanent magnet quadrupoles very powerful components of small aperture linacs. Results will be presented about past and present work on both fixed and variable strength permanent magnets suitable for use in and around linacs.

  7. The magnetization process: Hysteresis

    NASA Technical Reports Server (NTRS)

    Balsamel, Richard

    1990-01-01

    The magnetization process, hysteresis (the difference in the path of magnetization for an increasing and decreasing magnetic field), hysteresis loops, and hard magnetic materials are discussed. The fabrication of classroom projects for demonstrating hysteresis and the hysteresis of common magnetic materials is described in detail.

  8. Magnetic Storms

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce T.; Gonzalez, Walter D.

    1998-01-01

    One of the oldest mysteries in geomagnetism is the linkage between solar and geomagnetic activity. The 11-year cycles of both the numbers of sunspots and Earth geomagnetic storms were first noted by Sabine. A few years later, speculation on a causal relationship between flares and storms arose when Carrington reported that a large magnetic storm followed the great September 1859 solar flare. However, it was not until this century that a well-accepted statistical survey on large solar flares and geomagnetic storms was performed, and a significant correlation between flares and geomagnetic storms was noted. Although the two phenomena, one on the Sun and the other on the Earth, were statistically correlated, the exact physical linkage was still an unknown at this time. Various hypotheses were proposed, but it was not until interplanetary spacecraft measurements were available that a high-speed plasma stream rich in helium was associated with an intense solar flare. The velocity of the solar wind increased just prior to and during the helium passage, identifying the solar ejecta for the first time. Space plasma measurements and Skylab's coronagraph images of coronal mass elections (CMES) from the Sun firmly established the plasma link between the Sun and the Earth. One phenomenon associated with magnetic storms is brilliant "blood" red auroras, as shown.

  9. Superconducting magnet

    DOEpatents

    Satti, John A. (Naperville, IL)

    1980-01-01

    A superconducting magnet designed to produce magnetic flux densities of the order of 4 to 5 Webers per square meter is constructed by first forming a cable of a plurality of matrixed superconductor wires with each wire of the plurality insulated from each other one. The cable is shaped into a rectangular cross-section and is wound with tape in an open spiral to create cooling channels. Coils are wound in a calculated pattern in saddle shapes to produce desired fields, such as dipoles, quadrupoles, and the like. Wedges are inserted between adjacent cables as needed to maintain substantially radial placement of the long dimensions of cross sections of the cables. After winding, individual strands in each of the cables are brought out to terminals and are interconnected to place all of the strands in series and to maximize the propagation of a quench by alternating conduction from an inner layer to an outer layer and from top half to bottom half as often as possible. Individual layers are separated from others by spiraled aluminum spacers to facilitate cooling. The wound coil is wrapped with an epoxy tape that is cured by heat and then machined to an interference fit with an outer aluminum pipe which is then affixed securely to the assembled coil by heating it to make a shrink fit. In an alternate embodiment, one wire of the cable is made of copper or the like to be heated externally to propagate a quench.

  10. Effect of annealing temperature on optical properties of binary zinc tin oxide nano-composite prepared by sol-gel route using simple precursors: Structural and optical studies by DRS, FT-IR, XRD, FESEM investigations

    NASA Astrophysics Data System (ADS)

    Habibi, Mohammad Hossein; Mardani, Maryam

    2015-02-01

    Binary zinc tin oxide nano-composite was synthesized by a facile sol-gel method using simple precursors from the solutions consisting of zinc acetate, tin(IV) chloride and ethanol. Effect of annealing temperature on optical and structural properties was investigated using X-ray diffraction (XRD), diffuse reflectance spectra (DRS), field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR). XRD results revealed the existence of the ZnO and SnO2 phases. FESEM results showed that binary zinc tin oxide nano-composites ranges from 56 to 60 nm in diameter at 400 °C and 500 °C annealing temperatures respectively. The optical band gap was increased from 2.72 eV to 3.11 eV with the increasing of the annealing temperature. FTIR results confirmed the presence of zinc oxide and tin oxide and the broad absorption peaks at 3426 and 1602 cm-1 can be ascribed to the vibration of absorptive water, and the absorption peaks at 546, 1038 and 1410 cm-1 are due to the vibration of Zn-O or Sn-O groups in binary zinc tin oxide.

  11. Effect of Barium Loading on the Desulfation of Pt-BaO/Al2O3 Studied by H2 TPRX, TEM, Sulfur K-edge XANES, and in Situ TR-XRD

    SciTech Connect

    Kim, Do Heui; Szanyi, Janos; Kwak, Ja Hun; Szailer, Tamas; Hanson, Jonathan; Wang, Chong M.; Peden, Charles HF

    2006-06-01

    Desulfation processes were investigated over sulfated Pt BaO/Al2O3 with different barium loading (8 wt% and 20 wt%) by using H2 temperature programmed reaction (TPRX), transmission electron microscope (TEM) with energy dispersive spectroscopy (EDS), sulfur K-edge X-ray absorption near-edge spectroscopy (XANES), and in situ time-resolved X-ray diffraction (TR-XRD) techniques. Both sulfated samples (8 wt% and 20 wt%) form sulfate species (primarily BaSO4) as evidenced by S K-edge XANES and in situ TR-XRD. However, the desulfation behavior is strongly dependant on the barium loading. Sulfated Pt BaO(8)/Al2O3, consisting predominantly of surface BaO/BaCO3 species, displays more facile desulfation by H2 at lower temperatures than sulfated Pt BaO(20)/Al2O3, a material containing primarily bulk BaO/BaCO3 species. Therefore, after desulfation with H2 up to 1073 K, the amount of the remaining sulfur species on the former, mostly as BaS, is much less than on the latter. This suggests that the initial morphology differences between the two samples play a crucial role in determining the extent of desulfation and the temperature at which it occurs. It is concluded that the removal of sulfur is significantly easier at lower barium loading. This finding can potentially be important in developing more sulfur resistant LNT catalyst systems.

  12. Cobalt ferrite nano-composite coated on glass by Doctor Blade method for photo-catalytic degradation of an azo textile dye Reactive Red 4: XRD, FESEM and DRS investigations.

    PubMed

    Habibi, Mohammad Hossein; Parhizkar, Janan

    2015-11-01

    Cobalt ferrite nano-composite was prepared by hydrothermal route using cobalt nitrate, iron nitrate and ethylene glycol as chelating agent. The nano-composite was coated on glass by Doctor Blade method and annealed at 300 °C. The structural, optical, and photocatalytic properties have been studied by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and UV-visible spectroscopy (UV-Vis DRS). Powder XRD analysis confirmed formation of CoFe2O4 spinel phase. The estimated particle size from FESEM data was 50 nm. The calculated energy band gaps, obtained by Tauc relation from UV-Vis absorption spectra was 1.3 eV. Photocatalytic degradation of Reactive Red 4 as an azo textile was investigated in aqueous solution under irradiation showed 68.0% degradation of the dye within 100 min. The experimental enhanced activity compare to pure Fe2O3 can be ascribed to the formation of composite, which was mainly attributable to the transfer of electron and hole to the surface of composite and hinder the electron hole recombination. PMID:26116997

  13. The cation inversion and magnetization in nanopowder zinc ferrite obtained by soft mechanochemical processing

    SciTech Connect

    Milutinovi?, A.; Lazarevi?, Z.; Jovaleki?, ?.; Kuryliszyn-Kudelska, I.

    2013-11-15

    Graphical abstract: - Highlights: • Nano powder of ZnFe{sub 2}O{sub 4} prepared by a soft mechanochemical route after 18 h milling. • Phase formation controlled by XRD, Raman spectroscopy and magnetic measurements. • Size, strain and cation inversion degree determined by Rietveld refinement. • We were able to estimate the degree of inversion at most 0.348 and 0.4. • Obtained extremely high values of saturation magnetizations at T = 4.5 K. - Abstract: Two zinc ferrite nanoparticle materials were prepared by the same method – soft mechanochemical synthesis, but starting from different powder mixtures: (1) Zn(OH){sub 2}/?-Fe{sub 2}O{sub 3} and (2) Zn(OH){sub 2}/Fe(OH){sub 3}. In both cases a single phase system was obtained after 18 h of milling. The progress of the synthesis was controlled by X-ray diffractometry (XRD), Raman spectroscopy, TEM and magnetic measurements. Analysis of the XRD patterns by Rietveld refinement allowed determination of the cation inversion degree for both obtained single phase ZnFe{sub 2}O{sub 4} samples. The sample obtained from mixture (1) has the cation inversion degree 0.3482 and the sample obtained from mixture (2) 0.400. Magnetization measurements were confirmed that the degrees of the inversion were well estimated. Comparison with published data shows that used method of synthesis gives nano powder samples with extremely high values of saturation magnetizations: sample (1) 78.3 emu g{sup ?1} and sample (2) 91.5 emu g{sup ?1} at T = 4.5 K.

  14. Structure and magnetism of cobalt-doped ZnO thin films

    NASA Astrophysics Data System (ADS)

    Ivill, M.; Pearton, S. J.; Rawal, S.; Leu, L.; Sadik, P.; Das, R.; Hebard, A. F.; Chisholm, M.; Budai, J. D.; Norton, D. P.

    2008-01-01

    The structure and magnetic properties of Co-doped ZnO films are discussed in relation to cobalt doping levels and growth conditions. Films were deposited by pulsed-laser deposition (PLD) from ZnO targets containing cobalt concentrations from 0 to 30 at.%. The structure of the films is examined by x-ray diffraction (XRD) and transmission electron microscopy (TEM), and optical absorption is used to infer the substitution of cobalt inside the ZnO lattice. Magnetic properties are characterized by superconducting quantum interference device (SQUID) magnetometry. Films doped with cobalt concentrations of a few per cent appear to be composed of two magnetic components: a paramagnetic component and a low-field ferromagnetic component. Films doped with 30% cobalt show a larger FM signature at room temperature with clear hysteretic shape, but films grown at low pressure are plagued by the precipitation of metallic cobalt nanoparticles within the lattice which can be easily detected by XRD. These particles are well oriented with the ZnO crystal structure. By increasing the base pressure of the vacuum chamber to pressures above 1×10-5 Torr, metallic cobalt precipitates are undetectable in XRD scans, whereas the films still show an FM signature of ~0.08 ?B/Co. Depositions in the presence of oxygen background gas at 0.02 mTorr decreases the magnetization. The decreased magnetization with oxygen suggests that the activation of ferromagnetism depends on defects, such as oxygen vacancies, created during growth. Optical absorption measurements show a sequential increase in the Co+2 absorption peaks in these films, along with an almost linearly increasing bandgap with cobalt concentration suggesting a large solubility of cobalt in ZnO. Bright-field TEM imaging and electron diffraction do not show signs of precipitation; however, dark-field imaging shows circular areas of varying contrast which could be associated with cobalt precipitation. Therefore, the possibility that ferromagnetism results from secondary phases cannot be ruled out.

  15. Preparation and magnetic properties of spindle porous iron nanoparticles

    SciTech Connect

    Lv Baoliang; Xu Yao Wu Dong; Sun Yuhan

    2009-05-06

    Spindle porous iron nanoparticles were firstly synthesized by reducing the pre-synthesized hematite ({alpha}-Fe{sub 2}O{sub 3}) spindle particles with hydrogen gas. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption/desorption isotherms and vibrating sample magnetometry (VSM). A lattice shrinkage mechanism was employed to explain the formation process of the porous structure, and the adsorbed phosphate was proposed as a protective shell in the reduction process. N{sub 2} adsorption/desorption result showed a Brunauer-Emmett-Teller (BET) surface area of 29.7 m{sup 2}/g and a continuous pore size distribution from 2 nm to 100 nm. The magnetic hysteresis loop of the synthesized iron particles showed a saturation magnetization of 84.65 emu/g and a coercivity of 442.36 Oe at room temperature.

  16. Oleic acid coated magnetic nano-particles: Synthesis and characterizations

    NASA Astrophysics Data System (ADS)

    Panda, Biswajit; Goyal, P. S.

    2015-06-01

    Magnetic nano particles of Fe3O4 coated with oleic acid were synthesized using wet chemical route, which involved co-precipitation of Fe2+ and Fe3+ ions. The nano particles were characterized using XRD, TEM, FTIR, TGA and VSM. X-ray diffraction studies showed that nano particles consist of single phase Fe3O4 having inverse spinel structure. The particle size obtained from width of Bragg peak is about 12.6 nm. TEM analysis showed that sizes of nano particles are in range of 6 to 17 nm with a dominant population at 12 - 14 nm. FTIR and TGA analysis showed that -COOH group of oleic acid is bound to the surface of Fe3O4 particles and one has to heat the sample to 278° C to remove the attached molecule from the surface. Further it was seen that Fe3O4 particles exhibit super paramagnetism with a magnetization of about 53 emu/ gm.

  17. Perpendicular magnetic anisotropy of Mn{sub 4}N films on MgO(001) and SrTiO{sub 3}(001) substrates

    SciTech Connect

    Yasutomi, Yoko; Ito, Keita; Sanai, Tatsunori; Toko, Kaoru; Suemasu, Takashi

    2014-05-07

    We grew Mn{sub 4}N epitaxial thin films capped with Au layers on MgO(001) and SrTiO{sub 3}(001) substrates by molecular beam epitaxy. Perpendicular magnetic anisotropy (PMA) was confirmed in all the samples at room temperature from the magnetization versus magnetic field curves using superconducting quantum interference device magnetometer. From the ?-2? x-ray diffraction (XRD) and ?-2?{sub ?} XRD patterns, the ratios of perpendicular lattice constant c to in-plane lattice constant a, c/a, were found to be about 0.99 for all the samples. These results imply that PMA is attributed to the in-plane tensile strain in the Mn{sub 4}N films.

  18. Structure and magnetic properties of La substituted ZnFe2O4 nanoparticles synthesized by sol-gel autocombustion method

    NASA Astrophysics Data System (ADS)

    Masoudpanah, S. M.; Seyyed Ebrahimi, S. A.; Derakhshani, M.; Mirkazemi, S. M.

    2014-12-01

    ZnFe2-xLaxO4 (0magnetic properties were investigated by X-ray diffraction (XRD), infrared spectroscopy and vibrating sample magnetometer methods. The XRD results showed that the single phase La3+ substituted zinc ferrite nanoparticles exhibit partially inverse spinel structure with the crystallite size of 10-20 nm, which was also confirmed by transmission electron microscopy. The magnetic measurements show that the saturation magnetization (Ms) increases till x=0.05, due to the increase of inversity, and then decreases from x=0.05 to x=0.2, because of the decrease in the total moments with the La3+ substitution.

  19. Synthesis, structural and magnetic properties of La{sub 1-x}Cd{sub x}FeO{sub 3} (0.0 {<=} x {<=} 0.3) orthoferrites

    SciTech Connect

    Bellakki, Manjunath B.; Manivannan, V.; Das, Jaydip

    2009-07-01

    Nanocrystalline La{sub 1-x}Cd{sub x}FeO{sub 3} (0.0 {<=} x {<=} 0.3) solid solutions have been synthesized by a single-step solution combustion method at a relatively low temperature of 400 deg. C. The combustion-synthesized solid solutions were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and magnetic measurements. The crystal structure examined by XRD indicates that the samples were single-phase, and crystallize in an orthorhombic (space group, Pbnm no. 62) structure. The parent and doped compounds showed canted antiferromagnetic behavior associated with an increase in magnetic moment with Cd doping. The changes in magnetic properties of the materials are correlated to the changes in structural features resulting from the Rietveld structural refinement of the materials.

  20. Bio-inspired green synthesis of Fe3O4 spherical magnetic nanoparticles using Syzygium cumini seed extract

    NASA Astrophysics Data System (ADS)

    Venkateswarlu, Sada; Natesh Kumar, B.; Prasad, C. H.; Venkateswarlu, P.; Jyothi, N. V. V.

    2014-09-01

    A novel and bio-inspired Fe3O4 spherical magnetic nanoparticles (SMNPs) were synthesized using Syzygium cumini (S. cumini) seed extract, which is a non-toxic ecofriendly fruit waste material. S. cumini seed extract acts as a green solvent, reducing and capping agent in which sodium acetate acts as electrostatic stabilizing agent. The green synthesized nanoparticles were characterized with the help of various techniques such as X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), Energy-dispersive spectroscopy (EDS), Vibrating sample magnetometer (VSM), FTIR spectroscopy and nitrogen adsorption and desorption analysis techniques. The XRD study divulged that the synthesized SMNPs have inverse spinel cubic structure. The hysteresis loop of Fe3O4 nanoparticles shows an excellent ferromagnetic behavior with saturation magnetization value of 13.6 emu/g.

  1. Magnetic quantum dots and magnetic edge states

    NASA Astrophysics Data System (ADS)

    Lee, S. J.; Souma, S.; Ihm, G.; Chang, K. J.

    2004-04-01

    Starting with defining the magnetic edge state in a magnetic quantum dot, which becomes quite popular nowadays conjunction with a possible candidate for a high density memory device or spintronic materials, various magnetic nano-quantum structures are reviewed in detail. We study the magnetic edge states of the two dimensional electron gas in strong perpendicular magnetic fields. We find that magnetic edge states are formed along the boundary of the magnetic dot, which is formed by a nonuniform distribution of magnetic fields. These magnetic edge states circulate either clockwise or counterclockwise, depending on the number of missing flux quanta, and exhibit quite different properties, as compared to the conventional ones which are induced by electrostatic confinements in the quantum Hall system. We also find that a close relation between the quantum mechanical eigenstates and the classical trajectories in the magnetic dot. When a magnetic dot is located inside a quantum wire, the edge-channel scattering mechanism by the magnetic quantum dot is very different from that by electrostatic dots. Here, the magnetic dot is formed by two different magnetic fields inside and outside the dot. We study the ballistic edge-channel transport and magnetic edge states in this situation. When the inner field is parallel to the outer one, the two-terminal conductance is quantized and shows the features of a transmission barrier and a resonator. On the other hand, when the inner field is reversed, the conductance is not quantized and all channels can be completely reflected in some energy ranges. The difference between the above two cases results from the distinct magnetic confinements. We also describe successfully the edge states of magnetic quantum rings and others in detail.

  2. Investigation of structural, thermal and magnetic properties of cadmium substituted cobalt ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Venkata Reddy, Ch.; Byon, Chan; Narendra, B.; Baskar, D.; Srinivas, G.; Shim, Jaesool; Prabhakar Vattikuti, S. V.

    2015-06-01

    Cd substituted Cobalt ferrite nano particles are synthesis using co-precipitation method. The as prepared samples are calcinated at 300 and 600 °C respectively. The existence of single phase spinal cubic structure of the prepared ferrite material is confirmed by the powder XRD measurement. The surface morphology images, compositional features are studied by SEM with EDX, and TEM. From the FT-IR spectra the absorption bands observed at 595 and 402 cm-1 are attributed to vibrations of tetrahedral and octahedral complexes respectively. From the VSM data, parameters like magnetization, coercivity, remanent magnetization and remanent squareness are measured. The saturation magnetization value is increases with increasing calcination temperature. The DSC and TG-DTA curves reveal that the thermal stability of the prepared ferrite nanoparticles. The calcination temperature affects the crystallite size, morphology and magnetic properties of the samples.

  3. Thermal and magnetic behavior of Angustifolia Kunth bamboo fibers covered with Fe3O4 particles

    NASA Astrophysics Data System (ADS)

    Calvo, S.; Arias, N. P.; Giraldo, O.; Rosales-Rivera, A.; Moscoso, O.

    2012-08-01

    Several Angustifolia Kunth bamboo fibers, which have been previously treated with an alkaline solution, were coated with magnetite particles. The coating of the fibers was achieved by an in-situ co-precipitation method with Fe2+ and Fe3+in NaOH or NH4OH. The fibers were evaluated by chemical analysis using atomic absorption (A.A.) technique, structural characterization by X-ray diffraction (XRD), thermal stability with thermo-gravimetric analysis (TGA) in nitrogen at temperature range between 23 °C and 800 °C and magnetic behavior using vibrating sample magnetometry (VSM) applying a magnetic field between -27 KOe and 27 KOe at room temperature. We found that the thermal stability and magnetization depend of the synthesis method used to cover the Angustifolia Kunth bamboo fibers. In addition, an improved magnetic response was observed when NaOH solution is used to generate the magnetite coating on the fiber surface.

  4. Magnetism of Carbonados

    NASA Technical Reports Server (NTRS)

    Kletetschka, G.; Taylor, P. T.; Wasilewski, P. J.

    2000-01-01

    Origin of Carbonado is not clear. Magnetism of Carbonado comes from the surface, indicating contemporary formation of both the surface and magnetic carriers. The interior of carbonado is relatively free of magnetic phases.

  5. Samarium/Cobalt Magnets

    NASA Technical Reports Server (NTRS)

    Das, D.; Kumar, K.; Frost, R.; Chang, C.

    1985-01-01

    Intrinsic magnetic coercivities of samarium cobalt magnets made to approach theoretical limit of 350 kA/m by carefully eliminating oxygen from finished magnet by hot isostatic pressing (HIP). HIP process viable alternative to currently used sintering process.

  6. Magnetic particles

    NASA Technical Reports Server (NTRS)

    Chang, Manchium (Inventor); Colvin, Michael S. (Inventor); Rembaum, Alan (Inventor); Richards, Gil F. (Inventor)

    1987-01-01

    Metal oxide containing polymers and particularly styrene, acrylic or protein polymers containing fine, magnetic iron oxide particles are formed by combining a NO.sub.2 -substituted polymer with an acid such as hydrochloric acid in the presence of metal, particularly iron particles. The iron is oxidized to fine, black Fe.sub.3 O.sub.4 particles which deposit selectively on the polymer particles. Nitrated polymers are formed by reacting functionally substituted, nitrated organic compounds such as trinitrobenzene sulfonate or dinitrofluoro benzene with a functionally coreactive polymer such as an amine modified acrylic polymer or a protein. Other transition metals such as cobalt can also be incorporated into polymers using this method.

  7. Structural, magnetic and dielectric properties of polyaniline/MnCoFe2O4 nanocomposites

    NASA Astrophysics Data System (ADS)

    Chitra, Palanisamy; Muthusamy, Athianna; Jayaprakash, Rajan

    2015-12-01

    Ferromagnetic PANI containing MnCoFe2O4 nanocomposites were synthesized by in-situ chemical polymerization of aniline incorporated MnCoFe2O4 nanoparticles (20%, 10% w/w of fine powders) with and without ultrasonic treatment. The MnCoFe2O4 nanoparticles were synthesized by auto combustion method. The PANI/MnCoFe2O4 nanocomposites were characterized with Fourier transform infrared (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The average particle size of the resulting PANI/MnCoFe2O4 nanocomposites was confirmed from the TEM and XRD analysis. The structure and morphology of the composites were confirmed by FT-IR spectroscopy, XRD and SEM. In addition, the electrical and magnetic properties of the nanocomposites were investigated. The PANI/MnCoFe2O4 nanocomposites under applied magnetic field exhibited the hysteresis loops of ferromagnetic nature at room temperature. The variation of Dielectric constant, Dielectric loss, and AC conductivity of PANI/MnCoFe2O4 nanocomposites at room temperature as a function of frequency in the range 50 Hz-5 MHz has been studied. Effect of ultrasonication on the PANI/MnCoFe2O4 nanocomposites was also investigated.

  8. Preparation and characterization of supported magnetic nanoparticles prepared by reverse micelles

    PubMed Central

    Han, Luyang; Biskupek, Johannes; Kaiser, Ute; Ziemann, Paul

    2010-01-01

    Summary Monatomic (Fe, Co) and bimetallic (FePt and CoPt) nanoparticles were prepared by exploiting the self-organization of precursor loaded reverse micelles. Achievements and limitations of the preparation approach are critically discussed. We show that self-assembled metallic nanoparticles can be prepared with diameters d = 2–12 nm and interparticle distances D = 20–140 nm on various substrates. Structural, electronic and magnetic properties of the particle arrays were characterized by several techniques to give a comprehensive view of the high quality of the method. For Co nanoparticles, it is demonstrated that magnetostatic interactions can be neglected for distances which are at least 6 times larger than the particle diameter. Focus is placed on FePt alloy nanoparticles which show a huge magnetic anisotropy in the L10 phase, however, this is still less by a factor of 3–4 when compared to the anisotropy of the bulk counterpart. A similar observation was also found for CoPt nanoparticles (NPs). These results are related to imperfect crystal structures as revealed by HRTEM as well as to compositional distributions of the prepared particles. Interestingly, the results demonstrate that the averaged effective magnetic anisotropy of FePt nanoparticles does not strongly depend on size. Consequently, magnetization stability should scale linearly with the volume of the NPs and give rise to a critical value for stability at ambient temperature. Indeed, for diameters above 6 nm such stability is observed for the current FePt and CoPt NPs. Finally, the long-term conservation of nanoparticles by Au photoseeding is presented. PMID:21977392

  9. Synthesis and characterization of magnetic palygorskite nanoparticles and their application on methylene blue remotion from water

    NASA Astrophysics Data System (ADS)

    Middea, Antonieta; Spinelli, Luciana S.; Souza, Fernando G.; Neumann, Reiner; Gomes, Otavio da F. M.; Fernandes, Thais L. A. P.; de Lima, Luiz C.; Barthem, Vitoria M. T. S.; de Carvalho, Fernanda V.

    2015-08-01

    Recently there has been considerable interest in magnetic sorbents materials, which is added excellent capabilities such as sorption and magnetic response to an applied field. Accordingly, palygorskite nanoparticles were covered by magnetite using a co-precipitation technique and characterized by: X-ray fluorescence (XRF), X-ray diffraction (XRD), surface analysing and scanning electron microscopy (SEM) with element analysis and mapping, particle size, pore surface area (BET), density, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and zeta potential. Additionally, magnetic properties were studied by SQUID magnetometer, magnetic force microscopy (MFM) and also using a simple experimental setup. Magnetic nanoparticles produced had average diameters in a nanometric range. The amount of iron present in the nanoparticles increased by six times after the magnetization and a superparamagnetic behavior was exhibited with high saturation magnetization, from 4.0 × 10-4 Am2/kg to about 20 Am2/kg. A weight loss was also observed around 277 °C-339 °C by TGA, indicating a structural change from magnetite to maghemite, which confirms the magnetization of palygorskite. Batch adsorption experiments were carried out for the removal of methylene blue cationic dye from aqueous solution using pure and covered by magnetite palygorskite nanoparticles as adsorbents. Furthermore, about 90% of methylene blue was removed within 3 min using magnetized palygorskite.

  10. Photodegradation of Eosin Y Using Silver-Doped Magnetic Nanoparticles

    PubMed Central

    Alzahrani, Eman

    2015-01-01

    The purification of industrial wastewater from dyes is becoming increasingly important since they are toxic or carcinogenic to human beings. Nanomaterials have been receiving significant attention due to their unique physical and chemical properties compared with their larger-size counterparts. The aim of the present investigation was to fabricate magnetic nanoparticles (MNPs) using a coprecipitation method, followed by coating with silver (Ag) in order to enhance the photocatalytic activity of the MNPs by loading metal onto them. The fabricated magnetic nanoparticles coated with Ag were characterised using different instruments such as a scanning electron microscope (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDAX) spectroscopy, and X-ray diffraction (XRD) analysis. The average size of the magnetic nanoparticles had a mean diameter of about 48?nm, and the average particle size changed to 55?nm after doping. The fabricated Ag-doped magnetic nanoparticles were used for the degradation of eosin Y under UV-lamp irradiation. The experimental results revealed that the use of fabricated magnetic nanoparticles coated with Ag can be considered as reliable methods for the removal of eosin Y since the slope of evaluation of pseudo-first-order rate constant from the slope of the plot between ln?(Co/C) and the irradiation time was found to be linear. Ag-Fe3O4 nanoparticles would be considered an efficient photocatalyst to degrade textile dyes avoiding the tedious filtration step. PMID:26617638

  11. The Third Flight Magnet

    NASA Technical Reports Server (NTRS)

    McGhee, R. Wayne

    1998-01-01

    A self-shielded superconducting magnet was designed for the NASA Goddard Space Flight Center Adiabatic Demagnetization Refrigerator Program. This is the third magnet built from this design. The magnets utilize Cryomagnetics' patented ultra-low current technology. The magnetic system is capable of reaching a central field of two tesla at slightly under two amperes and has a total inductance of 1068 henries. This final report details the requirements of the magnet, the specifications of the resulting magnet, the test procedures and test result data for the third magnet (Serial # C-654-M), and recommended precautions for use of the magnet.

  12. Pharmacologically significant complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) of novel Schiff base ligand, (E)-N-(furan-2-yl methylene) quinolin-8-amine: Synthesis, spectral, XRD, SEM, antimicrobial, antioxidant and in vitro cytotoxic studies

    NASA Astrophysics Data System (ADS)

    Shakir, M.; Hanif, Summaiya; Sherwani, Mohd. Asif; Mohammad, Owais; Al-Resayes, Saud I.

    2015-07-01

    A novel series of metal complexes of the types, [ML2(H2O)2]Cl2 and [ML2]Cl2 [M = Mn(II), 1; Co(II), 2; Ni(II), 3; Cu(II), 4; and Zn(II), 5] were synthesized by the interaction of ligand, L (E)-N-(furan-2-yl methylene) quinolin-8-amine, derived from the condensation of 2-furaldehyde and 8-aminoquinoline. The synthesized ligand and its metal complexes were characterized on the basis of results obtained from elemental analysis, ESI-MS, XRD, SEM, TGA/DTA, FT-IR, UV-Vis, magnetic moment and 1H and 13C NMR spectroscopic studies. EPR parameters were recorded in case of complex 4. The comparative in-vitro antimicrobial activities against various pathogens with reference to known antibiotics and antioxidant activity against standard control at variable concentrations revealed that the metal complexes show enhanced antimicrobial and free radical scavenging activities in general as compared to free ligand. However, the complexes 1 and 5 have shown best antioxidant activity among all the metal complexes. Furthermore, comparative in-vitro antiproliferative activity on ligand and its metal chelates performed on MDA-MB-231 (breast carcinoma), KCL22 (blood lymphoid carcinoma), HeLa (cervical carcinoma) cell lines and normal cells (PBMC) revealed that metal chelates show moderate to good activity as compared to ligand where as complex 1 seems to be the most promising one possessing a broad spectrum of activity against all the selected cancer cell lines with IC50 < 2.10 ?M.

  13. The role of chelating agents on the structural and magnetic properties of ?-Fe2O3 nanoparticles

    NASA Astrophysics Data System (ADS)

    Lima, R. J. S.; Jesus, J. R.; Moura, K. O.; Jesus, C. B. R.; Duque, J. G. S.; Meneses, C. T.

    2011-06-01

    In this work we have studied the role of the addition of chelating agents on the structural and magnetic properties of ?-Fe2O3 nanoparticles obtained by the co-precipitation method. The precursors were prepared for the addition of different concentrations of the chelating agents: sucrose and glycerine. To obtain the nanoparticles, these precursors were heated in the temperature range between 200 and 400 °C. The samples have been characterized via x-ray diffraction (XRD), scanning electron microscopy (SEM), and magnetization measurements. The XRD data confirm that the crystalline phase is already formed at temperatures around 200 °C and there is a preferential growth to the (110) crystallographic plane to the sample at 0.01 mol/l of sucrose. Besides, a more careful analysis performed in the XRD, SEM, and zero field cooling and field cooling magnetization data clearly show the dependence of the size, shape, and size distribution of the samples as function of the chelating agent concentration.

  14. Magnetic properties, microstructure and mineralogical phases of technogenic magnetic particles (TMPs) in urban soils: Their source identification and environmental implications.

    PubMed

    Lu, Shenggao; Yu, Xiuling; Chen, Yuyin

    2016-02-01

    Magnetic measurement is an effective method to determine spatial distribution and the degree of heavy metal pollution and to identify various anthropogenic sources of heavy metals. The objectives of this investigation are to characterize the magnetic properties, microstructure and mineralogical phases of technogenic magnetic particles (TMPs) in urban soils and to discuss their potential environmental implications. The TMPs are separated from the urban topsoils of Luoyang city, China. The magnetic properties, morphology, and mineral phase of TMPs are studied using mineral magnetic measurement, scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM/EDS), X-ray diffraction, and synchrotron-radiation-based microprobe. The content of TMPs in urban topsoils ranges from 0.05 to 1.95% (on average 0.32%). The magnetic susceptibility of TMPs ranges from 4559×10(-8) to 23,661×10(-8)m(3)kg(-1) (on average 13,637×10(-8)m(3)kg(-1)). Thermomagnetic and bulk X-ray diffraction analyses indicate that main magnetic minerals of TMPs are magnetite (Fe3O4) and hematite (?-Fe2O3). The morphology of TMPs observed by SEM includes three shape types: spherule, irregular-shaped, and aggregate particles. The size of spherical TMPs ranges from 30 to about 200?m, with the largest percentage of 30-50?m. Synchrotron-radiation-based microprobe (?-XRF and ?-XRD) indicates that TMPs are enriched with heavy metals Pb, Cd, Zn, Cu, and Cr, which are incorporated into lattice or adsorbed on the surface of magnetite/hematite. The content of TMPs significantly relates with the Tomlinson Pollution Load Index (PLI) (R(2)=0.467), suggesting that it can be used as proxy indicator of degree of heavy metal contamination in urban soils. The magnetic properties, microstructure and mineralogical phases of TMPs can serve as the identification of pollution sources in urban soils. PMID:26588801

  15. Structural and magnetic properties of Co{sub 2}Ti{sub 1?x}Fe{sub x}Al (0 ? x ? 0.5) alloys

    SciTech Connect

    Pal, Lakhan Gupta, Sachin Suresh, K. G.

    2014-04-24

    In this work we studied the effect of partial Fe substitution for Ti on the structural and magnetic properties of the Co{sub 2}TiAl. X-ray diffraction analysis indicates the presence of B2 type disorder for x > 0, (111) reflections are absent for x > 0 which is the characteristic of B2 type disorder. XRD analysis also shows presence of second phase. Magnetization measurements also confirm the presence of dual phase. Curie temperature of the alloys increases with increase in Fe concentration. Saturation magnetic moments agree very well with those calculated by Slater-Pauling rule.

  16. An azodye-rhodamine-based fluorescent and colorimetric probe specific for the detection of Pd(2+) in aqueous ethanolic solution: synthesis, XRD characterization, computational studies and imaging in live cells.

    PubMed

    Mahapatra, Ajit Kumar; Manna, Saikat Kumar; Maiti, Kalipada; Mondal, Sanchita; Maji, Rajkishor; Mandal, Debasish; Mandal, Sukhendu; Uddin, Md Raihan; Goswami, Shyamaprosad; Quah, Ching Kheng; Fun, Hoong-Kun

    2015-02-21

    Azodye-rhodamine hybrid colorimetric fluorescent probe (L) has been designed and synthesized. The structure of L has been established based on single crystal XRD. It has been shown to act as a selective turn-on fluorescent chemosensor for Pd(2+) with >40 fold enhancement by exhibiting red emission among the other 27 cations studied in aqueous ethanol. The coordination features of the species of recognition have been computationally evaluated by DFT methods and found to have a distorted tetrahedral Pd(2+) center in the binding core. The probe (L) has been shown to detect Pd up to 0.45 ?M at pH 7.4. Furthermore, the probe can be used to image Pd(2+) in living cells. PMID:25537648

  17. Studies the alterations of biochemical and mineral contents in bone tissue of mus musculus due to aluminum toxicity and the protective action of desferrioxamine and deferiprone by FTIR, ICP-OES, SEM and XRD techniques

    NASA Astrophysics Data System (ADS)

    Sivakumar, S.; Khatiwada, Chandra Prasad; Sivasubramanian, J.

    The present study has attempt to analyze the changes in the biochemical and mineral contents of aluminum intoxicated bone and determine the protective action of desferrioxamine (DFO) and deferiprone (DFP) by using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy (ICP-OES), and scanning electron microscopy (SEM) techniques for four groups of animals such as control (Group I), aluminum intoxicated (Group II), Al + DFP (Group III) and Al + DFO + DFP (Group IV) treated groups respectively. The FTIR spectra of the aluminum intoxicated bone showed significant alteration in the biochemical constituents. The bands ratio at I1400/I877 significantly decreased from control to aluminum, but enhanced it by Al + DFP to Al + DFO + DFP treated bone tissue for treatments of 16 weeks. This result suggests that DFO and DFP are the carbonate inhibitor, recovered from chronic growth of bone diseases and pathologies. The alteration of proteins profile indicated by Amide I and Amide II, where peak area values decreased from control to aluminum respectively, but enhanced by treated with DFP (p.o.) and DFO + DFP (i.p.) respectively. The XRD analysis showed a decrease in crystallinity due to aluminum toxicity. Further, the Ca, Mg, and P contents of the aluminum exposed bone were less than those of the control group, and enhanced by treatments with DFO and DFP. The concentrations of trace elements were found by ICP-OES. Therefore, present study suggests that due to aluminum toxicity severe loss of bone minerals, decrease in the biochemical constituents and changes in the surface morphology.

  18. The influence of the stereochemistry of alanine residue on the solid state conformation and crystal packing of opioid peptides containing D-Ala or L-Ala in message domain--XRD and NMR study.

    PubMed

    Trzeciak-Karlikowska, Katarzyna; Bujacz, Anna; Ciesielski, W?odzimierz; Bujacz, Grzegorz D; Potrzebowski, Marek J

    2011-08-18

    In this work, an X-ray diffraction (XRD) and solid state NMR study of two tetrapeptides with different stereochemistry of alanine residue is presented using Tyr-(D-Ala)-Phe-Gly (1), an N-terminal sequence of opioid peptide dermorphin, and its biologically inactive analog Tyr-(L-Ala)-Phe-Gly (2). Single-crystal XRD proved that 1 crystallized under different conditions from exclusively one structure: a monoclinic crystal with P2(1) space group. In contrast, 2 very easily formed at least three crystallographic modifications, 2a (monoclinic P2(1)), 2b (orthorhombic P2(1)2(1)2) and 2c (tetragonal P4(1)2(1)2). Solid-state NMR spectroscopy was employed to investigate the structure and molecular dynamics of 1, 2a, and 2b. By employing different NMR experiments (dipolar dephasing and PILGRIM) and an analysis of the (13)C principal elements of the chemical shift tensor (CST), it was proven that the main skeleton of tetrapeptides is rigid, whereas significant differences in the molecular motion of the aromatic residues were observed. Comparing current data with those of previous studies (J. Phys. Chem. B2004, 108, 4535-4545 and Cryst. Growth Des. 2009, 9, 4050-4059), it can be assumed that an important preorganization mechanism anticipating the formation of peptide crystals containing D-Ala in sequence is the intramolecular CH-? interaction, which occurs for the amino acid with D stereochemistry. This effect may be responsible for the formation of only one crystallographic form of D-Ala peptides. PMID:21740057

  19. Formation of Ni chains induced by self-generated magnetic field

    SciTech Connect

    Gong Chunhong; Tian Juntao; Zhao Tao; Wu Zhishen; Zhang Zhijun

    2009-01-08

    Ultrafine chain-like Ni assemblies with a length of about 5 {mu}m were successfully prepared by the reduction of Ni salts with hydrazine hydrate under normal pressure in the absence of any inorganic or organic templates. The resulting Ni chains were characterized by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). Moreover, the growth process of the Ni chains was investigated for the first time, using transmission electron microscopy (TEM) and XRD as well, which is valuable to study the self-assembly mechanism of magnetic nanocrystallites. Results indicated that the novel chain-like Ni assemblies were integrated from Ni microspheres with a diameter of about 250 nm. Magnetic hysteresis measurement revealed that the Ni chains showed ferromagnetic behavior with a saturation magnetization of 15.07 emu/g and a coercivity of 115.1 Oe at room temperature. It was supposed that the self-generated magnetic field could induce the formation of the Ni chains.

  20. Magnetic properties of Nd-Ga-Fe{sub bal}-Nb-B alloy

    SciTech Connect

    Kim, Hyunkyu; Sung Kim, Chul; Yong An, Sung; Ryong Choi, Kang; Choi, Moonhee

    2014-05-07

    Here, we have synthesized Nd-Ga-Fe{sub bal}-Nb-B alloy by strip casting method. The crystalline and magnetic properties of sample were investigated with x-ray diffractometer (XRD), vibrating sample magnetometer (VSM), and Mössbauer spectrometer. The XRD pattern was analyzed with the Rietveld refinement method, indicating a tetragonal structure and the space group of P4{sub 2}/mnm. The temperature dependence of zero-field cooled (ZFC) magnetization curve was measured under applied field at temperature ranging from 4.2 to 740?K. From the ZFC curve, Curie temperature and spin reorientation temperature are determined to be 615?K and 130?K, respectively. Also, Mössbauer spectra were measured at various temperatures ranging from 4.2 to 620?K. Each spectrum was fitted with 6-sextets for Fe site (8j{sub 1}, 8j{sub 2}, 16k{sub 1}, 16k{sub 2}, 4c, and 4e), and magnetic hyperfine field, Isomer shift, electric quadrupole shift, and area ratio values were obtained from the fit. We observed the change in slope of magnetic hyperfine field and electric quadrupole shift at 130?K while the Curie temperature was determined to be 615?K from the measurement of zero velocity counter, agreeing with the values obtained from VSM measurements.

  1. Synthesis and magnetic characterization of magnetite obtained by monowavelength visible light irradiation

    SciTech Connect

    Lin, Yulong; Graduate School of the Chinese Academy of Sciences, Beijing 100039; School of Pharmaceutical Sciences, Hebei Medical University, Shijiazhuang 050017 ; Wei, Yu; Sun, Yuhan; Wang, Jing

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Magnetite was synthesized under monowavelength LED irradiation at room temperature. Black-Right-Pointing-Pointer Different wavelength irradiations led to distinctive characteristics of magnetite. Black-Right-Pointing-Pointer Particle sizes of magnetite were controlled by different irradiation wavelengths. Black-Right-Pointing-Pointer Wavelength affects the magnetic characteristics of magnetite. -- Abstract: Magnetite (Fe{sub 3}O{sub 4}) nanoparticles were controllably synthesized by aerial oxidation Fe{sup II}EDTA solution under different monowavelength light-emitting diode (LED) lamps irradiation at room temperature. The results of the X-ray diffraction (XRD) spectra show the formation of magnetite nanoparticle further confirmed by Fourier transform infrared spectroscope (FTIR) and the difference in crystallinity of as-prepared samples. Fe{sub 3}O{sub 4} particles are nearly spherical in shape based on transmission electron microscopy (TEM). Average crystallite sizes of magnetite can be controlled by different irradiation light wavelengths from XRD and TEM: 50.1, 41.2, and 20.3 nm for red, green, and blue light irradiation, respectively. The magnetic properties of Fe{sub 3}O{sub 4} samples were investigated. Saturation magnetization values of magnetic nanoparticles were 70.1 (sample M-625), 65.3 (sample M-525), and 58.2 (sample M-460) emu/g, respectively.

  2. Magnetic Membrane System

    DOEpatents

    McElfresh, Michael W.; (Livermore, CA); Lucas, Matthew S.; (Pasadena, CA)

    2004-12-30

    The present invention provides a membrane with magnetic particles. In one embodiment the membrane is created by mixing particles in a non-magnetic base. The membrane may act as an actuator, a sensor, a pump, a valve, or other device. A magnet is operatively connected to the membrane. The magnet acts on and changes the shape of the membrane.

  3. Contactless Magnetic Slip Ring

    NASA Technical Reports Server (NTRS)

    Kumagai, Hiroyuki (Inventor); Deardon, Joe D. (Inventor)

    1997-01-01

    A contactless magnetic slip ring is disclosed having a primary coil and a secondary coil. The primary and secondary coils are preferably magnetically coupled together, in a highly reliable efficient manner, by a magnetic layered core. One of the secondary and primary coils is rotatable and the contactless magnetic slip ring provides a substantially constant output.

  4. Magnetic Imaging Wolfgang Kuch

    E-print Network

    Kuch, Wolfgang

    Magnetic Imaging Wolfgang Kuch Freie Universit¨at Berlin, Institut f¨ur Experimentalphysik, Arnimallee 14, 14195 Berlin, Germany kuch@physik.fu-berlin.de Abstract. Imaging of magnetic domains has- ern techniques is used nowadays routinely for magnetic imaging of magnetic ma- terials

  5. A Magnetic Paradox

    ERIC Educational Resources Information Center

    Arndt, Ebe

    2006-01-01

    Two recent articles in this journal described how an air core solenoid connected to an ac power source may restore the magnetization of a bar magnet with an alternating magnetic field (see Figs. 1 and 2). Although we are quite accustomed to using a constant magnetic field in an air core solenoid to remagnetize a ferromagnet, it is puzzling that we…

  6. Synthesis, characterization and magnetic behavior of Co/MCM-41 nano-composites

    SciTech Connect

    Cuello, N.; Elías, V.; Crivello, M.; Oliva, M.; Eimer, G.

    2013-09-15

    Synthesis, structure and magnetic properties of Co/MCM-41 as magnetic nano-composites have been investigated. Mesoporous materials with different degrees of metal loading were prepared by wet impregnation and characterized by ICP, XRD, N{sub 2} adsorption, UV–vis DRS, TPR and EPMA-EDS. Cobalt oxide clusters and Co{sub 3}O{sub 4} nano-particles could be confined inside the mesopores of MCM-41, being this fact favored by the Co loading increasing. In addition, larger crystals of Co{sub 3}O{sub 4} detectable by XRD also grow on the surface when the Co loading is enhanced. The magnetic characterization was performed in a SQUID magnetometer using a maximum magnetic applied field µ{sub 0}Ha=1 T. While the samples with the higher Co loadings showed a behavior typically paramagnetic, a superparamagnetic contribution is more notorious for lower loadings, suggesting high Co species dispersion. - Graphical abstract: Room temperature hysteresis loops as a function of the Co content. Display Omitted - Highlights: • Co species as isolated Co{sup 2+}, oxide clusters and Co{sub 3}O{sub 4} nano-particles were detected. • For higher Co loads were detected, by XRD, Co{sub 3}O{sub 4} particles on the external surface. • The confining of Co species inside the mesopores was achieved by increasing Co load. • Paramagnetism from oxide clusters/nano-particles becomes dominant for higher Co loads. • Superparamagnetism can be assigned to Co species of small size and finely dispersed.

  7. Linear magnetic bearing

    NASA Technical Reports Server (NTRS)

    Studer, P. A. (inventor)

    1983-01-01

    A linear magnetic bearing system having electromagnetic vernier flux paths in shunt relation with permanent magnets, so that the vernier flux does not traverse the permanent magnet, is described. Novelty is believed to reside in providing a linear magnetic bearing having electromagnetic flux paths that bypass high reluctance permanent magnets. Particular novelty is believed to reside in providing a linear magnetic bearing with a pair of axially spaced elements having electromagnets for establishing vernier x and y axis control. The magnetic bearing system has possible use in connection with a long life reciprocating cryogenic refrigerator that may be used on the space shuttle.

  8. Hybrid superconducting magnetic suspensions

    SciTech Connect

    Tixador, P.; Hiebel, P.; Brunet, Y.

    1996-07-01

    Superconductors, especially high T{sub c} ones, are the most attractive materials to design stable and fully passive magnetic suspensions which have to control five degrees of freedom. The hybrid superconducting magnetic suspensions present high performances and a simple cooling mode. They consist of a permanent magnet bearing, stabilized by a suitable magnet-superconductor structure. Several designs are given and compared in terms of forces and stiffnesses. The design of the magnet bearing plays an important part. The superconducting magnetic bearing participates less in levitation but must provide a high stabilizing stiffness. This is achieved by the magnet configuration, a good material in term of critical current density and field cooling. A hybrid superconducting suspension for a flywheel is presented. This system consists of a magnet thrust bearing stabilized by superconductors interacting with an alternating polarity magnet structure. First tests and results are reported. Superconducting materials are magnetically melt-textured YBaCuO.

  9. Magnetic Damping For Maglev

    DOE PAGESBeta

    Zhu, S.; Cai, Y.; Rote, D. M.; Chen, S. S.

    1998-01-01

    Magnetic damping is one of the important parameters that control the response and stability of maglev systems. An experimental study to measure magnetic damping directly is presented. A plate attached to a permanent magnet levitated on a rotating drum was tested to investigate the effect of various parameters, such as conductivity, gap, excitation frequency, and oscillation amplitude, on magnetic damping. The experimental technique is capable of measuring all of the magnetic damping coefficients, some of which cannot be measured indirectly.

  10. Heteropolar Magnetic Suspension

    NASA Technical Reports Server (NTRS)

    Misovec, Kathleen; Johnson, Bruce; Downer, James; Eisenhaure, David; Hockney, Richard

    1990-01-01

    Compact permanent-magnet/electromagnet actuator has six degrees of freedom. Heteropolar magnetic actuator conceived for use as actively controlled vibration-isolating suspension device. Exerts forces along, and torques about, all three principal coordinate axes to resist all three components of translational vibration and all three components of rotational vibration. Inner cylinder suspended magnetically within outer cylinder. Electro-magnet coils interact with fields of permanent magnets to provide active control of suspending force and torque.

  11. Magnetically operated check valve

    NASA Technical Reports Server (NTRS)

    Morris, Brian G. (inventor); Bozeman, Richard J., Jr. (inventor)

    1994-01-01

    A magnetically operated check valve is disclosed. The valve is comprised of a valve body and a movable poppet disposed therein. A magnet attracts the poppet to hold the valve shut until the force of fluid flow through the valve overcomes the magnetic attraction and moves the poppet to an unseated, open position. The poppet and magnet are configured and disposed to trap a magnetically attracted particulate and prevent it from flowing to a valve seating region.

  12. Magnetic properties of Fe doped SmCrO{sub 3} perovskite

    SciTech Connect

    Bakshi, Venugopal Rao; Devarasetty, Suresh Babu; Prasad, Bandi Vittal; Gade, Narsinga Rao; Chou, C F

    2014-04-24

    The compound SmCr{sub 1?x} Fe{sub x}O{sub 3} perovskites were prepared by citric acid route. the samples were characterized by XRD and SEM. The temperature and field dependent magnetization measurements were carried out in the temperature range of 5K ?400 K at 0.01T field and ?5T to 5T field at 2K. SmCrO3 compound has shown two magnetic transition temperatures at 197 K and 38 K. The observed behavior at 197 K is the characteristic of anti-ferromagnetic ordering of Cr{sup 3+} moments with weak ferromagnetism. The drop in magnetization below 38 K is due to the spin reorientation of Sm{sup 3+} in anti ferromagnetic arrangement and Cr{sup 3+}spins. the doping of Fe in SmCrO{sub 3} compound has shown a decrease in T{sub N1} and also the two magnetization reversals at 177K and 57K. The magnetic behavior at low temperatures is (Tmagnetization reversals offers the characteristic switching of magnetization without changing the direction of the applied magnetic field.

  13. Magnetic Properties of One-Dimensional Sm-DOPED ZnO Nanostructures Fabricated by Hydrothermal Method

    NASA Astrophysics Data System (ADS)

    Lin, C. C.; Kung, C. Y.; Young, S. L.; Chen, H. Z.; Kao, M. C.; Horng, L.; Shih, Y. T.; Ou, C. R.; Lin, C. H.

    2013-08-01

    Well-defined ZnO and Sm-doped nanorods have been successfully fabricated by a low temperature hyderthermal process. The XRD patterns of both compositions with single diffraction peak (002) show the same wurtzite hexagonal structure. The radius of Sm-ZnO nanorods observed by FE-SEM is smaller than that of pure ZnO indicating the reduction of growth rate by the doping of Sm. Ferromagnetism is observed from the results of magnetization measurement. The increase of the saturation magnetization and decrease of coercivity reveal an association with the increase of oxygen vacancies induced by the doping of the Sm in the nanorods.

  14. Magnetic nanoparticle motion in external magnetic field

    NASA Astrophysics Data System (ADS)

    Usov, N. A.; Liubimov, B. Ya

    2015-07-01

    A set of equations describing the motion of a free magnetic nanoparticle in an external magnetic field in a vacuum, or in a medium with negligibly small friction forces is postulated. The conservation of the total particle momentum, i.e. the sum of the mechanical and the total spin momentum of the nanoparticle is taken into account explicitly. It is shown that for the motion of a nanoparticle in uniform magnetic field there are three different modes of precession of the unit magnetization vector and the director that is parallel the particle easy anisotropy axis. These modes differ significantly in the precession frequency. For the high-frequency mode the director points approximately along the external magnetic field, whereas the frequency and the characteristic relaxation time of the precession of the unit magnetization vector are close to the corresponding values for conventional ferromagnetic resonance. On the other hand, for the low-frequency modes the unit magnetization vector and the director are nearly parallel and rotate in unison around the external magnetic field. The characteristic relaxation time for the low-frequency modes is remarkably long. This means that in a rare assembly of magnetic nanoparticles there is a possibility of additional resonant absorption of the energy of alternating magnetic field at a frequency that is much smaller compared to conventional ferromagnetic resonance frequency. The scattering of a beam of magnetic nanoparticles in a vacuum in a non-uniform external magnetic field is also considered taking into account the precession of the unit magnetization vector and director.

  15. Tunable magnetic and magnetocaloric properties of La{sub 0.6}Sr{sub 0.4}MnO{sub 3} nanoparticles

    SciTech Connect

    Ehsani, M. H.; Kameli, P.; Ghazi, M. E.; Razavi, F. S.; Taheri, M.

    2013-12-14

    Nanoparticles of La{sub 0.6}Sr{sub 0.4}MnO{sub 3} with different particle sizes are synthesized by the nitrate-complex auto-ignition method. The structural and magnetic properties of the samples are investigated by X-Ray diffraction (XRD), Fourier transform infra-red (FT-IR) spectroscopy, transmission electron microscopy (TEM), and DC magnetization measurements. The XRD study coupled with the Rietveld refinement shows that all samples crystallize in a rhombohedral structure with the space group of R-3?C. The FT-IR spectroscopy and TEM images indicate formation of the perovskite structure with the average sizes of 20, 40, and 100?nm for the samples sintered at 700, 800, and 1100?°C, respectively. The DC magnetization measurements confirm tuning of the magnetic properties due to the particle size effects, e.g., reduction in the ferromagnetic moment and increase in the surface spin disorder by decreasing the particle size. The magnetocaloric effect (MCE) study based on isothermal magnetization vs. filed measurements in all samples reveals a relatively large MCE around the Curie temperature of the samples. The peak around the Curie temperature gradually broadens with reduction of the particle size. The data obtained show that although variations in the magnetic entropy and adiabatic temperature decrease by lowering the particle size, variation in the relative cooling power values are the same for all samples. These results make this material a proper candidate in the magnetic refrigerator application above room temperature at moderate fields.

  16. Magnetically Damped Furnace Bitter Magnet Coil 1

    NASA Technical Reports Server (NTRS)

    Bird, M. D.

    1997-01-01

    A magnet has been built by the National High Magnetic Field Laboratory for NASA on a cost reimbursement contract. The magnet is intended to demonstrate the technology and feasibility of building a magnet for space based crystal growth. A Bitter magnet (named after Francis Bitter, its inventor) was built consisting of four split coils electrically in series and hydraulically in parallel. The coils are housed in a steel vessel to reduce the fringe field and provide some on-axis field enhancement. The steel was nickel plated and Teflon coated to minimize interaction with the water cooling system. The magnet provides 0.14 T in a 184 mm bore with 3 kW of power.

  17. Radial magnetic field in magnetic confinement device

    NASA Astrophysics Data System (ADS)

    Xiong, Hao; Liu, Ming-Hai; Chen, Ming; Rao, Bo; Chen, Jie; Chen, Zhao-Quan; Xiao, Jin-Shui; Hu, Xi-Wei

    2015-09-01

    The intrinsic radial magnetic field (Br) in a tokamak is explored by the solution of the Grad-Shafranov equation in axisymmetric configurations through an expansion of the four terms of the magnetic surfaces. It can be inferred from the simulation results that at the core of the device, the tokamak should possess a three-dimensional magnetic field configuration, which could be reduced to a two-dimensional one when the radial position is greater than 0.6a. The radial magnetic field and the amzimuthal magnetic field have the same order of magnitude at the core of the device. These results can offer a reference for the analysis of the plasma instability, the property of the core plasma, and the magnetic field measurement. Project supported by the Special Domestic Program of ITER, China (Grant No. 2009GB105003).

  18. Nanocomposite Magnets: Transformational Nanostructured Permanent Magnets

    SciTech Connect

    2010-10-01

    Broad Funding Opportunity Announcement Project: GE is using nanomaterials technology to develop advanced magnets that contain fewer rare earth materials than their predecessors. Nanomaterials technology involves manipulating matter at the atomic or molecular scale, which can represent a stumbling block for magnets because it is difficult to create a finely grained magnet at that scale. GE is developing bulk magnets with finely tuned structures using iron-based mixtures that contain 80% less rare earth materials than traditional magnets, which will reduce their overall cost. These magnets will enable further commercialization of HEVs, EVs, and wind turbine generators while enhancing U.S. competitiveness in industries that heavily utilize these alternatives to rare earth minerals.

  19. Electrically Tunable Magnetism in Magnetic Topological Insulators

    NASA Astrophysics Data System (ADS)

    Zhang, Shou-Cheng; Wang, Jing; Lian, Biao

    2015-03-01

    The external controllability of the magnetic properties in topological insulators would be important both for fundamental and practical interests. Here we predict the electric-field control of ferromagnetism in a thin film of insulating magnetic topological insulators. The decrease of band inversion by the application of electric fields results in a reduction of magnetic susceptibility, and hence in the modication of magnetism. Remarkably, the electric field could even induce the magnetic quantum phase transition from ferromagnetism to paramagnetism. We further propose a topological transistor device in which the dissipationless charge transport of chiral edge states is controlled by an electric field. The simultaneous electrical control of magnetic order and chiral edge transport in such a device may lead to electronic and spintronic applications for topological insulators. This work is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under Contract No. DE-AC02-76SF00515.

  20. Iron oxide nanoparticles for magnetically assisted patterned coatings

    NASA Astrophysics Data System (ADS)

    Dodi, Gianina; Hritcu, Doina; Draganescu, Dan; Popa, Marcel I.

    2015-08-01

    Iron oxide nanoparticles able to magnetically assemble during the curing stage of a polymeric support to create micro-scale surface protuberances in a controlled manner were prepared and characterized. The bare Fe3O4 particles were obtained by two methods: co-precipitation from an aqueous solution containing Fe3+/Fe2+ ions with a molar ratio of 2:1 and partial oxidation of ferrous ions in alkaline conditions. The products were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and magnetization measurement. They were subsequently functionalized using oleic acid, sodium oleate, or non-ionic surfactant mixtures with various hydrophilic to lipophilic balance (HLB) values. Composite nanoparticle-polymer films prepared by spraying were deposited and cured by drying on glass slides under a static magnetic field in the range of 1.5-5.5 mT. Magnetic field generated surface roughness was evidenced by optical and scanning electron microscopy. The optimum hierarchical patterning was obtained with the nanoparticles produced by partial oxidation and functionalized with hydrophobic surfactants. Possible applications may include ice-phobic composite coatings.

  1. Magnetic field modification of optical magnetic dipoles.

    PubMed

    Armelles, Gaspar; Caballero, Blanca; Cebollada, Alfonso; Garcia-Martin, Antonio; Meneses-Rodríguez, David

    2015-03-11

    Acting on optical magnetic dipoles opens novel routes to govern light-matter interaction. We demonstrate magnetic field modification of the magnetic dipolar moment characteristic of resonant nanoholes in thin magnetoplasmonic films. This is experimentally shown through the demonstration of the magneto-optical analogue of Babinet's principle, where mirror imaged MO spectral dependencies are obtained for two complementary magnetoplasmonic systems: holes in a perforated metallic layer and a layer of disks on a substrate. PMID:25646869

  2. Large gap magnetic suspension system

    NASA Technical Reports Server (NTRS)

    Abdelsalam, Moustafa K.; Eyssa, Y. M.

    1991-01-01

    The design of a large gap magnetic suspension system is discussed. Some of the topics covered include: the system configuration, permanent magnet material, levitation magnet system, superconducting magnets, resistive magnets, superconducting levitation coils, resistive levitation coils, levitation magnet system, and the nitrogen cooled magnet system.

  3. Structural, Morphological, Electrical and Magnetic Properties of Nanostructured CoFe Thin Films Prepared by Spray Pyrolysis Deposition Method

    NASA Astrophysics Data System (ADS)

    Amirabadizadeh, Ahmad; Sarhaddi, Reza; Vahedipanah, Zahra; Mardani, Reza

    2015-08-01

    Nanostructured CoFe thin films were prepared on the glass substrates by spray pyrolysis deposition (SPD) method. The as-deposited films were separately annealed at 500°C in ambient air and hydrogen atmospheres to investigate the effect of annealing atmosphere on different properties of the deposited films. Structural, morphological, magnetic and electrical properties of annealed thin films were investigated by the X-ray diffractometer (XRD), scanning electron microscope (SEM), vibrating sample magnetometer (VSM) and four-point probe measurements, respectively. XRD patterns show that by changing the annealing atmosphere from ambient air to hydrogen, the crystal structure transformed from cubic spinel phase (Fd-3m) to cubic CsCl-type phase (Pm-3m). SEM images demonstrated that the morphology, grain size and thickness of annealed thin films depend greatly on the atmosphere type. Thickness of the films annealed in ambient air and hydrogen atmosphere were 378 and 356 nm, respectively. The morphology of the films changes from small sized granular for the ambient air-annealed films to coral-like structures for the hydrogen atmosphere annealed films. The magnetic properties of the annealed thin films depend on the annealing atmosphere, the applied field directions and film microstructural properties. Hydrogen annealing induced a perpendicular magnetic anisotropy in CoFe thin films. Room temperature hysteresis measurements show soft magnetic behavior of the hydrogen atmosphere annealed CoFe films in the perpendicular direction suggested its application in perpendicular magnetic recording media.

  4. Magnetic infrasound sensor

    DOEpatents

    Mueller, Fred M. (Los Alamos, NM); Bronisz, Lawrence (Los Alamos, NM); Grube, Holger (Los Alamos, NM); Nelson, David C. (Santa Fe, NM); Mace, Jonathan L. (Los Alamos, NM)

    2006-11-14

    A magnetic infrasound sensor is produced by constraining a permanent magnet inside a magnetic potential well above the surface of superconducting material. The magnetic infrasound sensor measures the position or movement of the permanent magnet within the magnetic potential well, and interprets the measurements. Infrasound sources can be located and characterized by combining the measurements from one or more infrasound sensors. The magnetic infrasound sensor can be tuned to match infrasound source types, resulting in better signal-to-noise ratio. The present invention can operate in frequency modulation mode to improve sensitivity and signal-to-noise ratio. In an alternate construction, the superconductor can be levitated over a magnet or magnets. The system can also be driven, so that time resolved perturbations are sensed, resulting in a frequency modulation version with improved sensitivity and signal-to-noise ratio.

  5. Structural, optical and magnetic properties of gadolinium sesquioxide nanobars synthesized via thermal decomposition of gadolinium oxalate

    SciTech Connect

    Manigandan, R.; Giribabu, K.; Suresh, R.; Vijayalakshmi, L.; Stephen, A.; Narayanan, V.

    2013-10-15

    Graphical abstract: - Highlights: • The cubic Gd{sub 2}O{sub 3} nanobars are synthesized by decomposition of C{sub 6}H{sub 20}Gd{sub 2}O{sub 22}. • The nanoparticles are rectangular bar shape with high porous surface. • The combination of magnetic and optical properties within a single particle. • The Gd{sub 2}O{sub 3} nanobars have tailorable nanostructure, wide bandgap and are paramagnetic. - Abstract: Gadolinium oxide nanobars were obtained by thermal decomposition of gadolinium oxalate, which was synthesized by the chemical precipitation method along with glycerol. The functional group analysis and formation of gadolinium oxide from gadolinium oxalate were characterized by the Fourier transform infrared spectroscopy and thermo gravimetric analyzer. The crystal structure, average crystallite size, and lattice parameter were analyzed by X-ray diffraction technique. Moreover, Raman shifts, elemental composition and morphology of the gadolinium oxide was widely investigated by the laser Raman microscope, X-ray photoelectron spectroscopy, FE-SEM-EDAX and HR-TEM, respectively. Furthermore, the optical properties like band gap, absorbance measurement of the gadolinium oxide were extensively examined. In addition, the paramagnetic property of gadolinium oxide nanobars was explored by the vibrating sample magnetometer.

  6. Janus nanobelts: fabrication, structure and enhanced magnetic-fluorescent bifunctional performance

    NASA Astrophysics Data System (ADS)

    Ma, Qianli; Yu, Wensheng; Dong, Xiangting; Wang, Jinxian; Liu, Guixia

    2014-02-01

    A new nanostructure of magnetic-fluorescent bifunctional Janus nanobelts with Fe3O4/PMMA as one half and Tb(BA)3phen/PMMA as the other half has been successfully fabricated by a specially designed parallel spinneret electrospinning technology. The morphology and properties of the final products were investigated in detail by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), biological microscopy (BM), vibrating sample magnetometry (VSM) and fluorescence spectroscopy. The results revealed that the [Fe3O4/PMMA]//[Tb(BA)3phen/PMMA] magnetic-fluorescent bifunctional Janus nanobelts possess superior magnetic and fluorescent properties due to their special nanostructure. Compared with Fe3O4/Tb(BA)3phen/PMMA composite nanobelts, the magnetic-fluorescent bifunctional Janus nanobelts provided better performance. The new magnetic-fluorescent bifunctional Janus nanobelts have potential applications in novel nano-bio-label materials, drug target delivery materials and future nanodevices due to their excellent magnetic-fluorescent properties, flexibility and insolubility. Moreover, the construction technique for the Janus nanobelts is of universal significance for the fabrication of other multifunctional Janus nanobelts.A new nanostructure of magnetic-fluorescent bifunctional Janus nanobelts with Fe3O4/PMMA as one half and Tb(BA)3phen/PMMA as the other half has been successfully fabricated by a specially designed parallel spinneret electrospinning technology. The morphology and properties of the final products were investigated in detail by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), biological microscopy (BM), vibrating sample magnetometry (VSM) and fluorescence spectroscopy. The results revealed that the [Fe3O4/PMMA]//[Tb(BA)3phen/PMMA] magnetic-fluorescent bifunctional Janus nanobelts possess superior magnetic and fluorescent properties due to their special nanostructure. Compared with Fe3O4/Tb(BA)3phen/PMMA composite nanobelts, the magnetic-fluorescent bifunctional Janus nanobelts provided better performance. The new magnetic-fluorescent bifunctional Janus nanobelts have potential applications in novel nano-bio-label materials, drug target delivery materials and future nanodevices due to their excellent magnetic-fluorescent properties, flexibility and insolubility. Moreover, the construction technique for the Janus nanobelts is of universal significance for the fabrication of other multifunctional Janus nanobelts. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr05472a

  7. Bacterial formation of tooeleite and mixed arsenic(III) or arsenic(V)-iron(III) gels in the Carnoulès acid mine drainage, France. A XANES, XRD, and SEM study.

    PubMed

    Morin, Guillaume; Juillot, Farid; Casiot, Corinne; Bruneel, Odile; Personné, Jean-Christian; Elbaz-Poulichet, Françoise; Leblanc, Marc; Ildefonse, Philippe; Calas, Georges

    2003-05-01

    The oxidation of Fe(II) in acid mine drainage (AMD) leads to the precipitation of Fe(III) compounds which may incorporate toxic elements, such as arsenic (As), within their structure or adsorb them at their surface, thus limiting their mobility. The present work provides evidence for spatial and seasonal variations of microbial activity that influence arsenite oxidation and As immobilization in the heavily contaminated AMD from the Carnoulès mine, Gard, France ([As III] = 80 to 280 mg x L(-1) in the acidic spring draining the waste-pile). In the first tens of meters of the AMD, the rapid oxidation of Fe(II) leads to the coprecipitation of large amounts of As with Fe(III) in bacterial mats. XRD, XANES, and SEM analyses of sediments and stromatolite samples revealed the unusual formation of As(III)-rich compounds, especially nanocrystalline tooeleite, Fe6(AsO3)4(SO4)(OH)4 x 4H2O, a rare ferric arsenite sulfate oxy-hydroxide mineral, together with XRD-amorphous mixed As(III)/As(V)-Fe(III) oxy-hydroxide compounds. In the wet season, the suspended sediments of the upstream zone essentially consist of tooeleite associated with am-As(III)-Fe(III) oxy-hydroxides, while am-As(V)-Fe(III) oxy-hydroxides, having As:Fe molar ratios as high as 0.6-0.8, dominate in the dry season. Comparing natural and bioassay samples revealed that the formation of As(III)-rich compounds in the wet season may be related to the metabolic activity of bacterial strains able to oxidize Fe(II) but not As(III). One of these strains, having an Acidithiobacillus ferrooxidans genotype, has been isolated from the Carnoulès AMD. In contrast, the formation of As(V)-rich compounds in the dry season can be related to both biotic and abiotic oxidation of As(III) to As(V). Some Thiomonas strains isolated from the Carnoulès AMD were shown to be able to catalyze the oxidation of As(III) to As(V) in solution. Therefore, they can promote the formation of mixed As(V)-Fe(III) oxy-hydroxides, provided enough Fe(II) oxidizes. These results yield a better understanding of natural processes at this site and may help in designing efficient As-removal processes. PMID:12775038

  8. First magnetic stars

    NASA Astrophysics Data System (ADS)

    Romanyuk, Iosif I.; Kudryavtsev, Dimitry O.

    2009-04-01

    This contribution dedicated to the analysis of the magnetism of chemically peculiar (CP) stars of the upper Main Sequence. We use our own measurements and published data to compile a catalog of magnetic CP stars containing a total of 326 objects with confidently detected magnetic fields and 29 stars which are very likely to possess magnetic field. Our analysis shows that the number of magnetic CP stars decreases with increasing field strength in accordance with exponential law, hotter and faster rotating stars have stronger fields. Intensity of depressions in the continua correlates with the magnetic field strength.

  9. Tamper resistant magnetic stripes

    DOEpatents

    Naylor, Richard Brian (Albuquerque, NM); Sharp, Donald J. (Albuquerque, NM)

    1999-01-01

    This invention relates to a magnetic stripe comprising a medium in which magnetized particles are suspended and in which the encoded information is recorded by actual physical rotation or alignment of the previously magnetized particles within the flux reversals of the stripe which are 180.degree. opposed in their magnetic polarity. The magnetized particles are suspended in a medium which is solid, or physically rigid, at ambient temperatures but which at moderately elevated temperatures, such as 40.degree. C., is thinable to a viscosity permissive of rotation of the particles therein under applications of moderate external magnetic field strengths within acceptable time limits.

  10. The effect of annealing on the structural and magnetic properties of Ni-ferrite nanocrystals

    NASA Astrophysics Data System (ADS)

    Ojha, Chaturbhuj; Verma, A. K.; Chauhan, S. S.; Shrivastava, A. K.

    2015-06-01

    Magnetic nanoparticles NiFe2O4 were prepared by chemical co-precipitation technique using the chlorides of Ni, Fe (III) and oleic acid. The precursors were annealed at different temperature 500, 700, and 900 °C. The XRD of samples show the presence of inverse cubic spinel structure. Grain size was determined using Scherrer formula and SEM technique. The Particle size, Lattice parameter and X-ray density were also estimated from X-ray diffraction data. The particles size was found to vary from 17nm to 37 nm and largely depends on the annealing temperature. Magnetization measurements have also carried out using VSM and it was found that saturation magnetization (Ms), Remanance (Mr) and coercivity (Hc) of nano ferrite materials are lower compared to bulk materials.

  11. Antibacterial activity of magnetic iron oxide nanoparticles synthesized by laser ablation in liquid.

    PubMed

    Ismail, Raid A; Sulaiman, Ghassan M; Abdulrahman, Safa A; Marzoog, Thorria R

    2015-08-01

    In this study, (50-110 nm) magnetic iron oxide (?-Fe2O3) nanoparticles were synthesized by pulsed laser ablation of iron target in dimethylformamide (DMF) and sodium dodecyl sulfate (SDS) solutions. The structural properties of the synthesized nanoparticles were investigated by using Fourier Transform Infrared (FT-IR) spectroscopy, UV-VIS absorption, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). The effect of laser fluence on the characteristics of these nanoparticles was studied. Antibacterial activities of iron oxide nanoparticles were tested against Gram-positive; Staphylococcus aureus and Gram-negative; Escherichia coli, Pseudomonas aeruginosa and Serratia marcescens. The results showed a noteworthy inhibition on both bacterial strains. The preparation conditions were found to affect significantly the antibacterial activity of these nanoparticles. The synthesized magnetic nanoparticles were used to capture rapidly S. aureus bacteria under the magnetic field effect. PMID:26042717

  12. One-step synthesis of magnetic chitosan for controlled release of 5-hydroxytryptophan

    NASA Astrophysics Data System (ADS)

    Santos Menegucci, Jucély dos; Santos, Mac-Kedson Medeiros Salviano; Dias, Diego Juscelino Santos; Chaker, Juliano Alexandre; Sousa, Marcelo Henrique

    2015-04-01

    In this work, nanoparticles of chitosan embedded with 25% (w/w) of iron oxide magnetic nanoparticles (magnetite/maghemite) with narrow size-distribution and with a loading efficiency of about 80% for 5-hydroxytryptophan (5-HTP), which is a chemical precursor in the biosynthesis of important neurotransmitters as serotonin, were synthesized with an initial mass ratio of 5-HTP/magnetic chitosan=1.2, using homogeneous precipitation by urea decomposition, in an efficient one-step procedure. Characterization of morphology, structure and surface were performed by XRD, TEM, FTIR, TGA, magnetization and zeta potential measurements, while drug loading and drug releasing were investigated using UV-vis spectroscopy. Kinetic drug release experiments under different pH conditions revealed a pH-sensitivecontrolled-release system, ruled by polymer swelling and/or particle dissolution.

  13. Structural, optical and magnetic properties of ultrafine mono dispersed Co doped maghemite nanoparticles

    NASA Astrophysics Data System (ADS)

    Gaur, Umesh Kumar; Priyadarshi, Himanshu; Kumar, Anil; Varma, G. D.

    2015-06-01

    Ultrafine Co doped ?- Fe2O3 nanoparticles have been synthesized by co-precipitation method and studied the effect of doping on structural, optical and magnetic properties. The XRD results confirm that synthesized material is ?- Fe2O3 nanoparticles, and the particle sizes are 10 and 3.6 nm for 5 and 10 % Co doped samples, respectively. FESEM, TEM and optical characterization reveal decrease in particle size and increase in band gap with increased doping level. Room temperature M-H plots indicate the increase in magnetization (63.7 emu/g for 10 % doped sample) with increasing doping. A small shift towards positive axis is observed in the M-H plots of doped sample. In this paper the correlation between the structural characteristics and observed optical and magnetic properties has been described and discussed.

  14. Thermal and soft magnetic properties of Co{sub 40}Fe{sub 22}Ta{sub 8}B{sub 30} glassy particles: In-situ X-ray diffraction and magnetometry studies

    SciTech Connect

    Taghvaei, Amir Hossein; Stoica, Mihai; Kaban, Ivan; Eckert, Jürgen; Bednar?ik, Jozef

    2014-08-07

    The structural evolution of Co{sub 40}Fe{sub 22}Ta{sub 8}B{sub 30} glassy particles has been studied by in-situ high-energy synchrotron X-ray diffraction (XRD) upon isochronal annealing. The changes in position, intensity, and full width at half maximum (FWHM) of the first and second diffuse maxima of the XRD patterns suggest the occurrence of irreversible structural relaxation upon the first heating up to a temperature close to the glass transition temperature T{sub g}. The variations in reduced pair correlation functions upon annealing are discussed in the frame of the topological fluctuation theory for structural relaxation. Isochronal annealing of the Co{sub 40}Fe{sub 22}Ta{sub 8}B{sub 30} glassy particles improves their soft magnetic properties through decreasing the coercivity and increasing the magnetic susceptibility, saturation magnetization, and Curie temperature.

  15. Multilayered Magnetic Gelatin Membrane Scaffolds.

    PubMed

    Samal, Sangram K; Goranov, Vitaly; Dash, Mamoni; Russo, Alessandro; Shelyakova, Tatiana; Graziosi, Patrizio; Lungaro, Lisa; Riminucci, Alberto; Uhlarz, Marc; Bañobre-López, Manuel; Rivas, Jose; Herrmannsdörfer, Thomas; Rajadas, Jayakumar; De Smedt, Stefaan; Braeckmans, Kevin; Kaplan, David L; Dediu, V Alek

    2015-10-21

    A versatile approach for the design and fabrication of multilayer magnetic scaffolds with tunable magnetic gradients is described. Multilayer magnetic gelatin membrane scaffolds with intrinsic magnetic gradients were designed to encapsulate magnetized bioagents under an externally applied magnetic field for use in magnetic-field-assisted tissue engineering. The temperature of the individual membranes increased up to 43.7 °C under an applied oscillating magnetic field for 70 s by magnetic hyperthermia, enabling the possibility of inducing a thermal gradient inside the final 3D multilayer magnetic scaffolds. On the basis of finite element method simulations, magnetic gelatin membranes with different concentrations of magnetic nanoparticles were assembled into 3D multilayered scaffolds. A magnetic-gradient-controlled distribution of magnetically labeled stem cells was demonstrated in vitro. This magnetic biomaterial-magnetic cell strategy can be expanded to a number of different magnetic biomaterials for various tissue engineering applications. PMID:26451743

  16. In vivo detection of magnetic labeled oxidized multi-walled carbon nanotubes by magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Li, Ruibin; Wu, Ren'an; Zhao, Liang; Qin, Hongqiang; Wu, Jianlin; Zhang, Jingwen; Bao, Ruyi; Zou, Hanfa

    2014-12-01

    Functionalized carbon nanotubes (f-CNTs) have been widely used in bio-medicine as drug carriers, bio-sensors, imaging agents and tissue engineering additives, which demands better understanding of their in vivo behavior because of the increasing exposure potential to humans. However, there are limited studies to investigate the in vivo biodistribution and elimination of f-CNTs. In this study, superparamagnetic iron oxides (SPIOs) were used to label oxidized multiwalled carbon nanotubes (o-MWCNTs) for in vivo distribution study of o-MWCNTs by magnetic resonance imaging (MRI). SPIO labeled o-MWCNTs ((SPIO)o-MWCNTs) were prepared by a hydrothermal reaction process, and characterized by TEM, XRD and magnetometer. (SPIO)o-MWCNTs exhibited superparamagnetic property, excellent biocompatibility and stability. The intravenously injected (SPIO)o-MWCNTs were observed in liver, kidney and spleen, while the subcutaneously injected (SPIO)o-MWCNTs could be only detected in sub mucosa. Most of the intravenously injected (SPIO)o-MWCNTs could be eliminated from liver, spleen, kidney and sub mucosa on 4 d post injection (P.I.). However, the residual o-MWCNTs could induce 30-40% MRI signal-to-noise ratio changes in these tissues even on 30 d P.I. This in vivo biodistribution and elimination information of o-MWCNTs will greatly facilitate the application of f-CNT based nanoproducts in biomedicine. In addition, the magnetic labeling method provides an approach to investigate the in vivo biodistribution and clearance of other nanomaterials.

  17. Structural, optical and magnetic properties of polycrystalline BaTi{sub 1-x}Fe{sub x}O{sub 3} ceramics

    SciTech Connect

    Dang, N. V.; Thanh, T. D.; Hong, L. V.; Lam, V. D.; Phan, The-Long

    2011-08-15

    Polycrystalline BaTi{sub 1-x}Fe{sub x}O{sub 3} ceramics have been prepared by conventional solid-state reaction. Their structural, optical and magnetic properties are then studied by means of x-ray diffraction (XRD), Raman scattering (RS) and absorption spectrometers, and a physical properties measurement system. Detailed analyses of XRD patterns and RS spectra reveal the phase separation of the tetragonal-hexagonal structure at a threshold concentration of x = 0.005. The increase in the Fe-doping content (x) leads to development of the hexagonal phase. Magnetic measurements prove that many BaTi{sub 1-x}Fe{sub x}O{sub 3} samples exhibit the room-temperature ferromagnetic order, excepting the samples with x = 0.02-0.06. The ferromagnetism depends strongly on concentration of Fe impurities. The nature of this ferromagnetism is discussed by means of the results of structural analyses and optical absorption spectra.

  18. Synthesis and magnetic properties of barium-calcium hexaferrite particles prepared by sol-gel and microemulsion techniques

    NASA Astrophysics Data System (ADS)

    Jotania, R. B.; Khomane, R. B.; Chauhan, C. C.; Menon, S. K.; Kulkarni, B. D.

    The preparation of W-type hexaferrite particles with the composition BaCa 2Fe 16O 27 by microemulsion and a stearic acid sol-gel method with and without surfactant has been investigated at various sintering temperatures. The structural and magnetic characteristics have been studied by X-ray diffraction (XRD), a vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetric (DSC) and Fourier transform infrared (FTIR) techniques. The effect of sintering temperature on the properties of BaCa 2Fe 16O 27 hexaferrites has been studied. The value of saturation magnetization ( Ms) depends on types of surfactant used. The sample prepared in the presence of polyoxyethylene (20) sorbitan monooleat (Tween 80) shows low saturation magnetization ( Ms=15.10 emu/g), whereas the other sample prepared in the presence of a surfactant cetyltrimethylammonium bromide (CTAB) exhibits high saturation magnetization ( Ms=24.60 emu/g) compared to the normal sample.

  19. Preparation, thermal and magnetic properties of Mn5(HPO4)2(PO4)2 4H2O

    NASA Astrophysics Data System (ADS)

    Bevara, Samatha; Achary, S. N.; Babu, P. D.; Tyagi, A. K.

    2015-06-01

    Herein we report preparation, thermal stability and magnetic properties of a complex phosphate of manganese (Mn5(HPO4)2(PO4)2 4H2O) from powder XRD, thermogravimetric and magnetization studies. The structure of the composition has cluster of five Mn2+ions each having octahedral coordination. The composition is stable up to 300°C and then it decomposes to Mn2P2O7 and Mn3(PO4)2. The FC and ZFC magnetic measurements indicate a ferromagnetic like sharp transition around 6 K. Below transition temperature, the field dependent magnetization indicates ferromagnetic like hysteresis loop and at higher field signature of antferromagnetic interactions is observed.

  20. Size effect on the magnetic properties of oleic acid stabilized substrate free BiFeO3 nanocrystals

    NASA Astrophysics Data System (ADS)

    Mahesh, Dabbugalla; Mahato, Bipul K.; Barman, Anjan; Mandal, Swapan K.

    2015-04-01

    We report here on the unique synthesis of BiFeO3 (BFO) nanocrystals of different size by using oleic acid as a capping agent and investigate the structural and magnetic properties. Oleic acid is found to be a good stabilizing agent to obtain different crystal size and distributions of BFO nanocrystals. Structural characterizations by X-ray diffraction (XRD) reveal the phase purity of all the samples. The BFO nanocrystals display strong size dependent magnetic properties showing increase in both magnetization (Ms) as well as in coercive field (Hc) with decreasing the crystal size due to the size confinement effect as well as change in magnetocrystalline anisotropy. The smallest BFO nanocrystal of size ~12 nm shows remarkably high (8.17 emu/g) magnetization value compared to previous reports. The results obtained here will be of immense important for advanced applications in electromagnetic devices.

  1. Optimizing the structure and magnetic properties of SmCo nanoferrites synthesized by auto-combustion processing techniques

    NASA Astrophysics Data System (ADS)

    Ahmed, M. A.; Okasha, N.; Mohamed, A. A.; Mmdouh, I.

    2014-05-01

    Nano-particles of polycrystalline SmxCoFe2-xO4; 0?x?0.04 were prepared using flash auto-combustion method. It was obtained as dried powder after the successful chemical reaction of their respective metal nitrates solutions in the presence of urea as fuel. Synthesis of materials in single phase cubic spinel is determined using XRD analyses. The structure and composition of Sm doped Co-ferrite were analyzed and the nanosize was confirmed by TEM micrograph. The magnetic susceptibility (?M) and hysteresis studies revealed the magnetic behavior through analysis of the change in Curie temperature (TC), saturation magnetization (Ms), effective magnetic moment (?eff), and coercivity (Hc) of these nanomaterials.

  2. Formaldehyde sensor based on Ni-doped tetrapod-shaped ZnO nanopowder induced by external magnetic field

    NASA Astrophysics Data System (ADS)

    Bai, Zikui; Xie, Changsheng; Hu, Mulin; Zhang, Shunping

    2008-12-01

    The sensors based on Ni-doped ZnO nanopowder with tetrapod-shape (T-ZnO) were fabricated by screen-printing technique with external magnetic field in different direction. The morphologies and crystal structures of the thick film were characterized by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM), respectively. Gas-sensing property of sensors responded to 100 ppm formaldehyde was also detected. The results show that the direction of magnetic field has crucial effect on the sensor sensitivity. The sensors based on 5 wt% Ni-doped T-ZnO induced by magnetic field in parallel direction to the thick film surface, has the optimization sensitivity, the shortest response and recovery time, which are 10.6, 16 and 15 s, respectively. The magnetic-field induction model and the gas-sensing mechanism of the Ni-doped T-ZnO are proposed.

  3. Magnetic Nanosystem for Cancer Therapy Using Oncocalyxone A, an Antitomour Secondary Metabolite Isolated from a Brazilian Plant

    PubMed Central

    Barreto, Antônio C. H.; Santiago, Vivian R.; Freire, Rafael M.; Mazzetto, Selma E.; Denardin, Juliano C.; Mele, Giuseppe; Cavalcante, Igor M.; Ribeiro, Maria E. N. P.; Ricardo, Nágila M. P. S.; Gonçalves, Tamara; Carbone, Luigi; Lemos, Telma L. G.; Pessoa, Otília D. L.; Fechine, Pierre B. A.

    2013-01-01

    This paper describes the investigation and development of a novel magnetic drug delivery nanosystem (labeled as MO-20) for cancer therapy. The drug employed was oncocalyxone A (onco A), which was isolated from Auxemma oncocalyx, an endemic Brazilian plant. It has a series of pharmacological properties: antioxidant, cytotoxic, analgesic, anti-inflammatory, antitumor and antiplatelet. Onco A was associated with magnetite nanoparticles in order to obtain magnetic properties. The components of MO-20 were characterized by XRD, FTIR, TGA, TEM and Magnetization curves. The MO-20 presented a size of about 30 nm and globular morphology. In addition, drug releasing experiments were performed, where it was observed the presence of the anomalous transport. The results found in this work showed the potential of onco A for future applications of the MO-20 as a new magnetic drug release nanosystem for cancer treatment. PMID:24013376

  4. Magnetic studies of mesoporous nanostructured iron oxide materials synthesized by one-step soft-templating.

    PubMed

    Jin, Jing; Hines, William A; Kuo, Chung-Hao; Perry, David M; Poyraz, Altug S; Xia, Yan; Zaidi, Taha; Nieh, Mu-Ping; Suib, Steven L

    2015-07-14

    A combined magnetization and (57)Fe spin-echo nuclear magnetic resonance (NMR) study has been carried out on mesoporous nanostructured materials consisting of the magnetite (Fe3O4) and maghemite (?-Fe2O3) phases. Two series of samples were synthesized using a recently developed one-step soft-templating approach with systematic variations in calcination temperature and reaction atmosphere. Nuclear magnetic resonance has been shown to be a valuable tool for distinguishing between the two magnetic iron oxide spinel phases, Fe3O4 and ?-Fe2O3, on the nanoscale as well as monitoring phase transformation resulting from oxidation. For the Fe3O4 and ?-Fe2O3 phases, peaks in the NMR spectra are attributed to Fe in the tetrahedral (A) sites and octahedral (B) sites. The magnetic field dependence of the peaks was observed and confirmed the site assignments. Fe3O4 on a nanoscale readily oxidizes to form ?-Fe2O3 and this was clearly evident in the NMR spectra. As evidenced by transmission electron microscope (TEM) images, the porous mesostructure for the iron oxide materials is formed by a random close-packed aggregation of nanoparticles; correspondingly, superparamagnetic behavior was observed in the magnetic measurements. Although X-ray diffraction (XRD) shows the spinel structure for the Fe3O4 and ?-Fe2O3 phases, unlike NMR, it is difficult to distinguish between the two phases with XRD. Nitrogen sorption isotherms characterize the mesoporous structures of the materials, and yield BET surface area values and limited BJH pore size distribution curves. PMID:26067028

  5. Superposition of DC magnetic fields by cascading multiple magnets in magnetic loops

    NASA Astrophysics Data System (ADS)

    Sun, Fei; He, Sailing

    2015-09-01

    A novel method that can effectively collect the DC magnetic field produced by multiple separated magnets is proposed. With the proposed idea of a magnetic loop, the DC magnetic field produced by these separated magnets can be effectively superimposed together. The separated magnets can be cascaded in series or in parallel. A novel nested magnetic loop is also proposed to achieve a higher DC magnetic field in the common air region without increasing the DC magnetic field in each magnetic loop. The magnetic loop can be made by a magnetic hose, which is designed by transformation optics and can be realized by the combination of super-conductors and ferromagnetic materials.

  6. Spin and orbital magnetization loops obtained using magnetic Compton scattering

    SciTech Connect

    Itou, M.; Sakurai, Y.; Koizumi, A.

    2013-02-25

    We present an application of magnetic Compton scattering (MCS) to decompose a total magnetization loop into spin and orbital magnetization contributions. A spin magnetization loop of SmAl{sub 2} was measured by recording the intensity of magnetic Compton scattering as a function of applied magnetic field. Comparing the spin magnetization loop with the total magnetization one measured by a vibrating sample magnetometer, the orbital magnetization loop was obtained. The data display an anti-coupled behavior between the spin and orbital magnetizations and confirm that the orbital part dominates the magnetization.

  7. Preparation and characterization of magnetic Fe3O4-chitosan nanoparticles loaded with isoniazid

    NASA Astrophysics Data System (ADS)

    Qin, H.; Wang, C. M.; Dong, Q. Q.; Zhang, L.; Zhang, X.; Ma, Z. Y.; Han, Q. R.

    2015-05-01

    A novel and simple method has been proposed to prepare magnetic Fe3O4-chitosan nanoparticles loaded with isoniazid (Fe3O4/CS/INH nanocomposites). Efforts have been made to develop isoniazid (INH) loaded chitosan (CS) nanoparticles by ionic gelation of chitosan with tripolyphosphate (TPP). The factors that influence the preparation of chitosan nanoparticles, including the TPP concentration, the chitosan/TPP weight ratio and the chitosan concentration on loading capacity and encapsulation efficiency of chitosan nanoparticles were studied. The magnetic Fe3O4 nanoparticles were prepared by co-precipitation method of Fe2+ and Fe3+. Then the magnetic Fe3O4/CS/INH nanocomposites were prepared by ionic gelation method. The magnetic Fe3O4 nanoparticles and magnetic Fe3O4/CS/INH nanocomposites were characterized by XRD, TEM, FTIR and SQUID magnetometry. The in vitro release of Fe3O4/CS/INH nanocomposites showed an initial burst release in the first 10 h, followed by a more gradual and sustained release for 48 h. It is suggested that the magnetic Fe3O4/CS/INH nanocomposites may be exploited as potential drug carriers for controlled-release applications in magnetic targeted drugs delivery system.

  8. A novel magnetic 4A zeolite adsorbent synthesised from kaolinite type pyrite cinder (KTPC)

    NASA Astrophysics Data System (ADS)

    Wang, Weiqing; Feng, Qiming; Liu, Kun; Zhang, Guofan; Liu, Jing; Huang, Yang

    2015-01-01

    As a solid waste, kaolinite type pyrite cinder (KTPC) is a special pyrite cinder, its mineral components include metakaolin and magnetite, and the chemical compositions of these minerals include SiO2, Al2O3, FeO and Fe2O3. In this study, a novel magnetic 4A zeolite adsorbent was synthesised from KTPC using the hydrothermal method, and the optimum hydrothermal synthesis conditions were investigated using X-ray diffraction (XRD) and by determining the specific surface area (SSA) and the saturated cation exchange adsorption capacity (SCEAC) to Cs+. Under the optimum hydrothermal synthesis conditions, the magnetic 4A zeolite adsorbent can be synthesised with high crystallinity, and the SSA and SCEAC to Cs+ are 24.49 m2/g and 106.63 mg/g, respectively. The further characterisations of pore size distribution, scanning electron microscopy (SEM), energy dispersive X-ray (EDX), thermogravimetry-derivative thermogravimetry-differential thermal analysis (TG-DTG-DTA), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM) were performed. The results revealed that magnetic particles are coated onto the zeolite surface and further form magnetic aggregates, and the existing magnetic particles in KTPC do not change their crystal structure and do not affect the synthesis of the 4A zeolite. In addition, the synthesised 4A zeolite adsorbent can be used as a magnetic adsorbent in wastewater treatment with high magnetic sensitivity and is thermally stable up to approximately 900 °C.

  9. Confocal {mu}-XRF, {mu}-XAFS, and {mu}-XRD Studies of Sediment from a Nuclear Waste Disposal Natural Analogue Site and Fractured Granite Following a Radiotracer Migration Experiment

    SciTech Connect

    Denecke, Melissa A.; Brendebach, Boris; Rothe, Joerg; Simon, Rolf; Janssens, Koen; Nolf, Wout de; Vekemans, Bart; Falkenberg, Gerald; Somogyi, Andrea; Noseck, Ulrich

    2007-02-02

    Combined {mu}-XRF, {mu}-XAFS, and {mu}-XRD investigations of a uranium-rich tertiary sediment, from a nuclear repository natural analogue site, and a fractured granite bore core section after a column tracer experiment using a Np(V) containing cocktail have been performed. Most {mu}-XRF/{mu}-XAFS measurements are recorded in a confocal geometry to provide added depth information. The U-rich sediment results show uranium to be present as a tetravalent phosphate and that U(IV) is associated with As(V). Arsenic present is either As(V) or As(0). The As(0) forms thin coatings on the surface of pyrite nodules. A hypothesis for the mechanism of uranium immobilization is proposed, where arsenopyrite acted as reductant of ground water dissolved U(VI) leading to precipitation of less soluble U(IV) and thereby forming As(V). Results for the granite sample show the immobilized Np to be tetravalent and associated with facture material.

  10. The magnetic genome project

    NASA Astrophysics Data System (ADS)

    Sanvito, Stefano

    2015-03-01

    Magnetic materials underpin a vast and diverse range of modern technologies, going from data storage to energy production and use. However, the choice of magnets for mainstream applications is limited to a few dozens and the development of a new high-performance magnetic compound is a long and often unpredictable process. Here we describe a systematic pathway to the discovery of novel magnetic materials for multiple applications, which demonstrates an unprecedented throughput and speed up in the discovery process. We have constructed a massive electronic structures library for Heusler alloys containing 236,856 materials. We have then extracted those magnetic compounds with specific electronic properties, such as half-metallicity and large magnetization density, and finally established whether these can be fabricated at thermodynamical equilibrium. Based on our analysis we have identified 249 stable new intermetallic Heuslers, including 21 new magnets. Our work paves the way for large scale design of novel magnetic materials at unprecedented speed.

  11. Magnetic Fields and Plasmas

    SciTech Connect

    Schep, T.J.

    2004-03-15

    Plasmas and magnetic fields are inseparably related in numerous physical circumstances. This is not only the case in natural occurring plasmas like the solar corona and the earth magnetic tail, but also in laboratory plasmas like tokamaks and stellarators.

  12. SSC MAGNET TECHNOLOGY

    E-print Network

    Taylor, C.

    2010-01-01

    under magnetic load is less than with stainless steelmagnetic performance; therefore, R&D cryostats were used. At BNL, stainless steelstainless steel and aluminum alloy collars. The short model tests have verified that adequate magnetic

  13. Magnetic Graphene Nanohole Superlattices

    E-print Network

    Yu, Decai; Liu, Miao; Liu, Wei; Liu, Feng

    2008-01-01

    We investigate the magnetic properties of nano-holes (NHs) patterned in graphene using first principles calculations. We show that superlattices consisting of a periodic array of NHs form a new family of 2D crystalline "bulk" magnets whose collective magnetic behavior is governed by inter-NH spin-spin interaction. They exhibit long-range magnetic order well above room temperature. Furthermore, magnetic semiconductors can be made by doping magnetic NHs into semiconducting NH superlattices. Our findings offer a new material system for fundamental studies of spin-spin interaction and magnetic ordering in low dimensions, and open up the exciting opportunities of making engineered magnetic materials for storage media and spintronics applications.

  14. Active magnetic regenerator

    DOEpatents

    Barclay, John A. (Los Alamos, NM); Steyert, William A. (Los Alamos, NM)

    1982-01-01

    The disclosure is directed to an active magnetic regenerator apparatus and method. Brayton, Stirling, Ericsson, and Carnot cycles and the like may be utilized in an active magnetic regenerator to provide efficient refrigeration over relatively large temperature ranges.

  15. Magnetically responsive enzyme powders

    NASA Astrophysics Data System (ADS)

    Pospiskova, Kristyna; Safarik, Ivo

    2015-04-01

    Powdered enzymes were transformed into their insoluble magnetic derivatives retaining their catalytic activity. Enzyme powders (e.g., trypsin and lipase) were suspended in various liquid media not allowing their solubilization (e.g., saturated ammonium sulfate and highly concentrated polyethylene glycol solutions, ethanol, methanol, 2-propanol) and subsequently cross-linked with glutaraldehyde. Magnetic modification was successfully performed at low temperature in a freezer (-20 °C) using magnetic iron oxides nano- and microparticles prepared by microwave-assisted synthesis from ferrous sulfate. Magnetized cross-linked enzyme powders were stable at least for two months in water suspension without leakage of fixed magnetic particles. Operational stability of magnetically responsive enzymes during eight repeated reaction cycles was generally without loss of enzyme activity. Separation of magnetically modified cross-linked powdered enzymes from reaction mixtures was significantly simplified due to their magnetic properties.

  16. Magnetic Resonance Imaging (MRI)

    MedlinePLUS

    ... Your Best Self Smart Snacking Losing Weight Safely Magnetic Resonance Imaging (MRI) KidsHealth > Teens > Cancer Center > Diagnostic Tests > Magnetic Resonance Imaging (MRI) Print A A A Text Size What's ...

  17. Magnetic Resonance Cholangiopancreatography (MRCP)

    MedlinePLUS

    ... a powerful magnetic field, radio waves and a computer to evaluate the liver, gallbladder, bile ducts, pancreas ... powerful magnetic field, radio frequency pulses and a computer to produce detailed pictures of organs, soft tissues, ...

  18. Magnetic assisted statistical assembly

    E-print Network

    Cheng, Diana I

    2008-01-01

    The objective of this thesis is to develop a process using magnetic forces to assemble micro-components into recesses on silicon based integrated circuits. Patterned SmCo magnetic thin films at the bottom of recesses are ...

  19. Experiments on Magnetic Materials

    ERIC Educational Resources Information Center

    Schneider, C. S.; Ertel, John P.

    1978-01-01

    Describes the construction and use of a simple apparatus to measure the magnetization density and magnetic susceptibility of ferromagnetic, paramagnetic, and the diamagnetic solids and liquids. (Author/GA)

  20. MRI (Magnetic Resonance Imaging)

    MedlinePLUS

    ... Radiation-Emitting Products and Procedures Medical Imaging MRI (Magnetic Resonance Imaging) Share Tweet Linkedin Pin it More ... MB) Also available in Other Language versions . Description Magnetic resonance imaging (MRI) is a medical imaging procedure ...

  1. Magnetic field mapper

    NASA Technical Reports Server (NTRS)

    Masters, R. M.; Stenger, F. J.

    1969-01-01

    Magnetic field mapper locates imperfections in cadmium sulphide solar cells by detecting and displaying the variations of the normal component of the magnetic field resulting from current density variations. It can also inspect for nonuniformities in other electrically conductive materials.

  2. Magnetic reconnection in sheared solar magnetic arcades

    SciTech Connect

    Choe, G.S.

    1996-12-31

    The evolution of solar magnetic arcades is investigated with the use of MHD simulations imposing resistivity on sheared magnetic fields. It is found that there is a critical amount of shear, over which magnetic reconnection can take place in an arcade-like field geometry to create a magnetic island. The process leading to reconnection cannot be solely attributed to a tearing instability, but rather to a reactive evolution of the magnetic arcade under resistivity. The natures of the arcade reconnection are governed by the spatial pattern of resistivity. A fast reconnection with a small shock angle can only be achieved when the diffusion region is localized. In this case, a highly collimated reconnection outflow can tear the plasmoid into a pair, and most of principal features in solar eruptive processes are reproduced.

  3. Magnetic Separation Dynamics of Colloidal Magnetic Nanoparticles

    SciTech Connect

    Kaur, Maninder; Zhang, Huijin; Qiang, You

    2013-08-14

    Surface functionalized magnetic nanoparticles (MNPs) are appealing candidates for analytical separation of heavy metal ions from waste water and separation of actinides from spent nuclear fuel. This work studies the separation dynamics and investigates the appropriate magnetic-field gradients. A dynamic study of colloidal MNPs was performed for steady-state flow. Measurements were conducted to record the separation time of particles as a function of magnetic field gradient. The drag and magnetic forces play a significant role on the separation time. A drop in saturation magnetization and variation of particle size occurs after surface functionalization of the MNPs; these are the primary factors that affect the separation time and velocity of the MNPs. The experimental results are correlated to a theoretical one-dimensional model.

  4. Aligned and exchange-coupled L1{sub 0} (Fe,Co)Pt-based magnetic films

    SciTech Connect

    Liu, Y.; George, T. A.; Skomski, R.; Sellmyer, D. J.

    2012-04-01

    Films of aligned L1{sub 0}-structure (Fe,Co)Pt with fcc Fe(Co,Pt) are synthesized by co-sputtering Fe, Co, and Pt on an (001) MgO substrate with in situ heating at 830 deg. C. The nanostructures and magnetic properties of the films are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and superconducting quantum interference device (SQUID). The compositions of the samples (Fe,Co){sub x}Pt{sub 1-x} are designed to maintain an atomic Fe: Co ratio of 65: 35 while increasing the Fe,Co content in each successive sample. In samples with low Fe and Co concentration, the XRD patterns exhibit three strong peaks, namely L1{sub 0} (Fe,Co)Pt (001), L1{sub 0} (Fe,Co)Pt (002), and MgO (002). A fourth peak is observed in samples with high Fe and Co concentration and identified as fcc (002). The XRD patterns confirm the formation of L1{sub 0}-ordered (Fe,Co)Pt and its epitaxial growth on MgO. TEM shows that the (Fe,Co)Pt films form isolated magnetic grains of about 100 nm in diameter. Hysteresis-loop measurements show that the increase of the Fe,Co concentration from 57.3 to 68.3 at % enhances the saturation magnetization M{sub s} from 1245 emu/cm{sup 3} to 1416 emu/cm{sup 3}, and the coercivity decreases from 32 kOe to 8.9 kOe. The nominal maximum energy product per grain is 64 MGOe.

  5. High temperature structural and magnetic properties of cobalt nanorods

    SciTech Connect

    Ait Atmane, Kahina; Zighem, Fatih; Soumare, Yaghoub; Ibrahim, Mona; Boubekri, Rym; Maurer, Thomas; Margueritat, Jeremie; Piquemal, Jean-Yves; Ott, Frederic; Chaboussant, Gregory; Schoenstein, Frederic; Jouini, Noureddine; Viau, Guillaume

    2013-01-15

    We present in this paper the structural and magnetic properties of high aspect ratio Co nanoparticles ({approx}10) at high temperatures (up to 623 K) using in-situ X ray diffraction (XRD) and SQUID characterizations. We show that the anisotropic shapes, the structural and texture properties are preserved up to 500 K. The coercivity can be modelled by {mu}{sub 0}H{sub C}=2(K{sub MC}+K{sub shape})/M{sub S} with K{sub MC} the magnetocrystalline anisotropy constant, K{sub shape} the shape anisotropy constant and M{sub S} the saturation magnetization. H{sub C} decreases linearly when the temperature is increased due to the loss of the Co magnetocrystalline anisotropy contribution. At 500 K, 50% of the room temperature coercivity is preserved corresponding to the shape anisotropy contribution only. We show that the coercivity drop is reversible in the range 300-500 K in good agreement with the absence of particle alteration. Above 525 K, the magnetic properties are irreversibly altered either by sintering or by oxidation. - Graphical abstract: We present in this paper the structural and magnetic properties of high aspect ratio Co nanorods ({approx}10) at high temperatures (up to 623 K) using in-situ X-ray diffraction and SQUID characterizations. We show that the anisotropic shapes, the structural and texture properties are preserved up to 500 K. Above 525 K, the magnetic properties are irreversibly altered either by sintering or by oxidation. Highlights: Black-Right-Pointing-Pointer Ferromagnetic Co nanorods are prepared using the polyol process. Black-Right-Pointing-Pointer The structural and texture properties of the Co nanorods are preserved up to 500 K. Black-Right-Pointing-Pointer The magnetic properties of the Co nanorods are irreversibly altered above 525 K.

  6. Carbon nanotubes/magnetite hybrids prepared by a facile synthesis process and their magnetic properties

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Ni, Qing-Qing; Natsuki, Toshiaki; Fu, Yaqin

    2009-07-01

    In this paper, a facile synthesis process is proposed to prepare multiwalled carbon nanotubes/magnetite (MWCNTs/Fe 3O 4) hybrids. The process involves two steps: (1) water-soluble CNTs are synthesized by one-pot modification using potassium persulfate (KPS) as oxidant. (2) Fe 3O 4 is assembled along the treated CNTs by employing a facile hydrothermal process with the presence of hydrazine hydrate as the mineralizer. The treated CNTs can be easily dispersed in aqueous solvent. Moreover, X-ray photoelectron spectroscopy (XPS) analysis reveals that several functional groups such as potassium carboxylate (-COOK), carbonyl (-C dbnd O) and hydroxyl (-C-OH) groups are formed on the nanotube surfaces. The MWCNTs/Fe 3O 4 hybrids are characterized with respect to crystal structure, morphology, element composition and magnetic property by X-ray diffraction (XRD), transmission electron microscopy (TEM), XPS and superconducting quantum interference device (SQUID) magnetometer. XRD and TEM results show that the Fe 3O 4 nanoparticles with diameter in the range of 20-60 nm were firmly assembled on the nanotube surface. The magnetic property investigation indicated that the CNTs/Fe 3O 4 hybrids exhibit a ferromagnetic behavior and possess a saturation magnetization of 32.2 emu/g. Further investigation indicates that the size of assembled Fe 3O 4 nanoparticles can be turned by varying experiment factors. Moreover, a probable growth mechanism for the preparation of CNTs/Fe 3O 4 hybrids was discussed.

  7. The effect of gallium substitution on the microstructure and magnetic properties of yttrium iron garnet

    NASA Astrophysics Data System (ADS)

    Zaini, N. Z. M.; Ibrahim, N. B.

    2015-09-01

    Y3Fe(5-y)GayO12 (y = 0, 0.4, 1.4 and 2,4) thin films were prepared by sol-gel method and annealed for 2h in oxygen. The thin film's characteristic were studied by an X-ray diffraction (XRD), a field emission scanning electron microscope (FESEM) and a vibration sample magnetometer (VSM). The XRD show that all films have the garnet phase structure. The grain size particles measured using FESEM were between 45.08 nm to 51.58 nm, and the thickness were between 42 nm to 90 nm. The magnetic properties measured using VSM showed that result was shown with hysteresis loop. The magnetization saturation decreased from 144.26 to 2.76 emu/cm3 with the increasing substitution gallium. The substitution for y = 2.4 was shown the saturation magnetization was very low. The coercivity increased 35 to 75 Oe due the the increasing grain size.

  8. Dopant concentration dependence of structure, optical, and magnetic properties of ZnO:Fe thin films

    NASA Astrophysics Data System (ADS)

    Hong, Ruijin; Wen, Herui; Liu, Caiming; Chen, Jinglin; Liao, Jinsheng

    2011-01-01

    The effects of Fe-dopant concentration on the structure, optical, and magnetic properties of ZnO thin films were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), optical transmittance, absorption, photoluminescence (PL), and magnetic measurements. XRD spectra indicated that the doping of Fe atoms could not only change the lattice constant of ZnO but also improve the crystalline quality of ZnO thin films. And the Zn (0 0 2) diffraction peak at round 36.34°(2 ?) was detected with increasing Fe content for the substitution of the Zn in the ZnO film. The band gap edge shifted toward longer wavelength with increase in Fe doping. Moreover, near band edge emission gradually increased with increase in Fe content (up to about 0.82 wt%), and then abruptly decreased due to the concentration quenching effect. Magnetic measurements confirmed that the ferromagnetic behavior of Fe-doped ZnO was correlated with the dopant concentration.

  9. Structural and magnetic properties of Cr-substituted NiZnCo ferrite nanopowders

    NASA Astrophysics Data System (ADS)

    Li, Le-Zhong; Tu, Xiao-Qiang; Wang, Rui; Peng, Long

    2015-05-01

    Cr-substituted NiZnCo ferrite nanopowders, Ni0.5-xZn0.5CrxCo0.1Fe1.9O4 (0?x?0.20), were synthesized by sol-gel auto-combustion method. The effect of Cr substitution on the structural and magnetic properties have been investigated. Differential thermal analysis-thermogravimetry (DTA-TG), X-ray diffraction (XRD), Fourier transform infrared spectro-scopy (FT-IR) and vibrating sample magnetometer (VSM) measurements were used to characterize chemical, structural and magnetic properties. The DTA-TG results indicate that there are three steps of combustion process. FT-IR spectra confirm the formation of spinel structure during the self-propagation combustion. XRD results indicate that the lattice parameter and the X-ray density decrease, and the average crystallite size increase with increasing Cr substitution. And Fe2O3 secondary impurity phase formed with excess Cr substitution. The saturation magnetization increases with the increase of Cr substitution when x?0.05, and decreased when x>0.05. Meanwhile, the coercivity monotonically decreases with the increase of Cr substitution.

  10. Electrical and magnetic behavior of iron doped nickel titanate (Fe3+/NiTiO3) magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Lenin, Nayagam; Karthik, Arumugam; Sridharpanday, Mathu; Selvam, Mohanraj; Srither, Saturappan Ravisekaran; Arunmetha, Sundarmoorthy; Paramasivam, Palanisamy; Rajendran, Venkatachalam

    2016-01-01

    Iron doped nickel titanate (Fe3+/NiTiO3) ferromagnetic nanoparticles with different concentrations of Fe (0.2, 0.4, and 0.6 mol) were synthesized using precipitation route with precursor source such as nickel nitrate and iron nitrate solutions. The prepared magnetic nanopowders were investigated through X-ray diffraction (XRD), Fourier transform infrared, scanning electron microscope, X-ray fluorescence, Brunauer-Emmett-Teller, vibrating sample magnetometer, and electrochemical impedance spectroscopy to explore the structural, ferromagnetic, and dielectric properties. The obtained XRD pattern shows formation of iron doped nickel titanate in orthorhombic structure. The crystallite size ranges from 57 to 21 nm and specific surface area ranges from 11 to 137 m2 g-1. The hysteresis loops of nanomagnetic materials show ferromagnetic behavior with higher magnitude of coercivity (Hc) 867-462 Oe. The impedance analysis of ferromagnetic materials explores the ferro-dielectric behavior with enhanced properties of Fe3+/NiTiO3 nanoparticles at higher Fe content.

  11. Testing the Capture Magnet

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image of a model capture magnet was taken after an experiment in a Mars simulation chamber at the University of Aarhus, Denmark. It has some dust on it, but not as much as that on the Mars Exploration Rover Spirit's capture magnet. The capture and filter magnets on both Mars Exploration Rovers were delivered by the magnetic properties team at the Center for Planetary Science, Copenhagen, Denmark.

  12. Axial Halbach Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2008-01-01

    Axial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control.

  13. Magnetic Fields Analogous to electric field, a magnet

    E-print Network

    Bertulani, Carlos A. - Department of Physics and Astronomy, Texas A&M University

    Magnetic Fields Analogous to electric field, a magnet produces a magnetic field, B Set up a B field two ways: Moving electrically charged particles Current in a wire Intrinsic magnetic field Basic characteristic of elementary particles such as an electron #12;Magnetic Fields Magnetic field lines Direction

  14. Magnetism Theory Group / POSTECH Magnetism Theory Group / POSTECH

    E-print Network

    Min, Byung Il

    Magnetism Theory Group / POSTECH #12;Magnetism Theory Group / POSTECH #12;Magnetism Theory Group / POSTECH #12;Magnetism Theory Group / POSTECH #12;Magnetism Theory Group / POSTECH J.H . Park et al. #12;'s of FeinCsm e tal The chargeandorbitalordering geom etryin YB a C o 2 O 5 S. K. Kwon etal .Magnetism Theory

  15. Magnetism and Interface Research Profile

    E-print Network

    Giger, Christine

    Magnetism and Interface Physics Research Profile Our group investigates magnetic phenomena in thin determines the magnetic and electrical properties of metal multilayers and hybrid metal issues include the development of integrated spintronic devices, storage media, and nanoscale magnets

  16. Chemical speciation of size-segregated floor dusts and airborne magnetic particles collected at underground subway stations in Seoul, Korea.

    PubMed

    Jung, Hae-Jin; Kim, BoWha; Malek, Md Abdul; Koo, Yong Sung; Jung, Jong Hoon; Son, Youn-Suk; Kim, Jo-Chun; Kim, HyeKyoung; Ro, Chul-Un

    2012-04-30

    Previous studies have reported the major chemical species of underground subway particles to be Fe-containing species that are generated from wear and friction processes at rail-wheel-brake and catenaries-pantographs interfaces. To examine chemical composition of Fe-containing particles in more details, floor dusts were collected at five sampling locations of an underground subway station. Size-segregated floor dusts were separated into magnetic and non-magnetic fractions using a permanent magnet. Using X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDX), iron metal, which is relatively harmless, was found to be the dominating chemical species in the floor dusts of the <25 ?m size fractions with minor fractions of Mg, Al, Si, Ca, S, and C. From SEM analysis, the floor dusts of the <25 ?m size fractions collected on railroad ties appeared to be smaller than 10 ?m, indicating that their characteristics should somewhat reflect the characteristics of airborne particles in the tunnel and the platform. As most floor dusts are magnetic, PM levels at underground subway stations can be controlled by removing magnetic indoor particles using magnets. In addition, airborne subway particles, most of which were smaller than 10 ?m, were collected using permanent magnets at two underground subway stations, namely Jegi and Yangjae stations, in Seoul, Korea. XRD and SEM/EDX analyses showed that most of the magnetic aerosol particles collected at Jegi station was iron metal, whereas those at Yangjae station contained a small amount of Fe mixed with Na, Mg, Al, Si, S, Ca, and C. The difference in composition of the Fe-containing particles between the two subway stations was attributed to the different ballast tracks used. PMID:22381374

  17. Noble gas magnetic resonator

    DOEpatents

    Walker, Thad Gilbert; Lancor, Brian Robert; Wyllie, Robert

    2014-04-15

    Precise measurements of a precessional rate of noble gas in a magnetic field is obtained by constraining the time averaged direction of the spins of a stimulating alkali gas to lie in a plane transverse to the magnetic field. In this way, the magnetic field of the alkali gas does not provide a net contribution to the precessional rate of the noble gas.

  18. Nuclear Magnetic Resonance

    NASA Astrophysics Data System (ADS)

    Andrew, E. R.

    2009-06-01

    Author's preface; 1. Introduction; 2. Basic theory; 3. Experimental methods; 4. Measurement of nuclear properties and general physical applications; 5. Nuclear magnetic resonance in liquids and gases; 6. Nuclear magnetic resonance in non-metallic solids; 7. Nuclear magnetic resonance in metals; 8. Quadrupole effects; Appendices 1-6; Glossary of symbols; Bibliography and author index; Subject index.

  19. Magnetism in meteorites

    NASA Technical Reports Server (NTRS)

    Herndon, J. M.; Rowe, M. W.

    1974-01-01

    An overview is presented of magnetism in meteorites. A glossary of magnetism terminology followed by discussion of the various techniques used for magnetism studies in meteorites are included. The generalized results from use of these techniques by workers in the field are described. A brief critical analysis is offered.

  20. Magnetic nanohole superlattices

    SciTech Connect

    Liu, Feng

    2013-05-14

    A magnetic material is disclosed including a two-dimensional array of carbon atoms and a two-dimensional array of nanoholes patterned in the two-dimensional array of carbon atoms. The magnetic material has long-range magnetic ordering at a temperature below a critical temperature Tc.

  1. Magnetic Forces, and Devices

    E-print Network

    Cruz-Pol, Sandra L.

    /10/spintronics-discover-could-lead-to- magnetic-batteries.php Applica'ons Motors Transformers MRI current element Forces on a Charge EQFe = Analogous to the electric force: We have magnetic Torque on a Current Loop in a Magnetic Field CD Motor Magne'c Torque and Moment The torque

  2. Conductivity of magnetic fluids

    SciTech Connect

    Dyupovkin, N.I.

    1995-09-01

    Consideration of the conductivity of magnetic fluids based on nonaqueous media demonstrates that the concentration dependence of conductivity exhibits a maximum for stable systems. Dependences of the conductivity of magnetic fluids on the magnitude of magnetic field are reported, and results of the study are discussed.

  3. Iron dominated magnets

    SciTech Connect

    Fischer, G.E.

    1985-07-01

    These two lectures on iron dominated magnets are meant for the student of accelerator science and contain general treatments of the subjects design and construction. The material is arranged in the categories: General Concepts and Cost Considerations, Profile Configuration and Harmonics, Magnetic Measurements, a few examples of ''special magnets'' and Materials and Practices. Extensive literature is provided.

  4. Magnetic Refrigeration Development

    NASA Technical Reports Server (NTRS)

    Deardoff, D. D.; Johnson, D. L.

    1984-01-01

    Magnetic refrigeration is being developed to determine whether it may be used as an alternative to the Joule-Thomson circuit of a closed cycle refrigerator for providing 4 K refrigeration. An engineering model 4-15 K magnetic refrigerator has been designed and is being fabricated. This article describes the overall design of the magnetic refrigerator.

  5. Metallic Magnetic Hetrostructures

    E-print Network

    Leung, Chi Wah

    .2.2 Domains and magnetization processes 1.2.2.1 Domains and domain walls 1.2.2.2 Magnetization reversal and hysteresis 1.2.2.3 Modelling of magnetization process 1.3 Sputter deposition of thin films in this project 1.3.1 Substrate preparation 1.3.2 ‘UFO...

  6. A Magnet Spring Model

    ERIC Educational Resources Information Center

    Fay, T. H.; Mead, L.

    2006-01-01

    The paper discusses an elementary spring model representing the motion of a magnet suspended from the ceiling at one end of a vertical spring which is held directly above a second magnet fixed on the floor. There are two cases depending upon the north-south pole orientation of the two magnets. The attraction or repelling force induced by the…

  7. Common Magnets, Unexpected Polarities

    ERIC Educational Resources Information Center

    Olson, Mark

    2013-01-01

    In this paper, I discuss a "misconception" in magnetism so simple and pervasive as to be typically unnoticed. That magnets have poles might be considered one of the more straightforward notions in introductory physics. However, the magnets common to students' experiences are likely different from those presented in educational…

  8. Crystallization process and magnetic property of Fe81Zr3Nb6B10 alloy

    NASA Astrophysics Data System (ADS)

    Sun, Y. M.; Yu, W. Q.; Long, D.; Zhang, Y.; Hua, Z.

    2015-11-01

    Fe81Zr3Nb6B10 amorphous alloy was prepared by melt-spinning and annealed at various temperatures. The thermal property, microstructure and magnetic property were investigated by differential thermal analysis (DTA), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The crystallization process of Fe81Zr3Nb6B10 alloy is as follow: Amorphous ? residual amorphous + ?-Fe + ?-Mn type ? ?-Fe solid solution. Coercivity (Hc) of Fe81Zr3Nb6B10 alloy changes complexly, which abruptly deteriorates at 843 K and then softens with increasing annealing temperature (Ta).

  9. SYNTHESIS AND CHARACTERIZATION OF ADVANCED MAGNETIC MATERIALS

    SciTech Connect

    Monica Sorescu

    2004-09-22

    The work described in this grant report was focused mainly on the properties of novel magnetic intermetallics. In the first project, we synthesized several 2:17 intermetallic compounds, namely Nd{sub 2}Fe{sub 15}Si{sub 2}, Nd{sub 2}Fe{sub 15}Al{sub 2}, Nd{sub 2}Fe{sub 15}SiAl and Nd{sub 2}Fe{sub 15}SiMn, as well as several 1:12 intermetallic compounds, such as NdFe{sub 10}Si{sub 2}, NdFe{sub 10}Al{sub 2}, NdFe{sub 10}SiAl and NdFe{sub 10}MnAl. In the second project, seven compositions of Nd{sub x}Fe{sub 100-x-y}B{sub y} ribbons were prepared by a melt spinning method with Nd and B content increasing from 7.3 and 3.6 to 11 and 6, respectively. The alloys were annealed under optimized conditions to obtain a composite material consisting of the hard magnetic Nd{sub 2}Fe{sub 14}B and soft magnetic {alpha}-Fe phases, typical of a spring magnet structure. In the third project, intermetallic compounds of the type Zr{sub 1}Cr{sub 1}Fe{sub 1}T{sub 0.8} with T = Al, Co and Fe were subjected to hydrogenation. In the fourth project, we performed three crucial experiments. In the first experiment, we subjected a mixture of Fe{sub 3}O{sub 4} and Fe (80-20 wt %) to mechanochemical activation by high-energy ball milling, for time periods ranging from 0.5 to 14 hours. In the second experiment, we ball-milled Fe{sub 3}O{sub 4}:Co{sup 2+} (x = 0.1) for time intervals between 2.5 and 17.5 hours. Finally, we exposed a mixture of Fe{sub 3}O{sub 4} and Co (80-20 wt %) to mechanochemical activation for time periods ranging from 0.5 to 10 hours. In all cases, the structural and magnetic properties of the systems involved were elucidated by X-ray diffraction (XRD), Moessbauer spectroscopy and hysteresis loop measurements. The four projects resulted in four papers, which were published in Intermetallics, IEEE Transactions on Magnetics, Journal of Materials Science Letters and Materials Chemistry and Physics. The contributions reveal for the first time in literature the effect of substitutions on the hyperfine magnetic field of neodymium-based intermetallics, the correlation between structure and magnetic properties in spring magnets, the unique effects induced by hydrogenation on the hyperfine parameters of iron-rich intermetallics and the characteristics of the ball milling process in systems containing magnetite.

  10. Synthesis and size dependent magnetic behaviour of nanocrystalline Cu0.2Ni0.8Fe2O4 ferrite

    NASA Astrophysics Data System (ADS)

    Dolia, S. N.; Sharma, P. K.; Dhawan, M. S.; Samariya, A.; Pareek, S. P.; Prasad, Arun S.; Singhal, R. K.; Kumar, Sudhish

    2011-10-01

    Particle size has significant effect on the magnetic properties of nano-particles. Nano-particles of Cu-Ni ferrite have been synthesized by the co-precipitation method. Different particle sizes (3nm-9 nm) were obtained by annealing the prepared samples at various temperatures. The specimens characterized using XRD confirmed the formation of cubic spinel structure. The samples show typical superparamagnetic behaviour above blocking temperature. The particle size increases with increasing the annealing temperature. The saturation magnetization & blocking temperature increases with particle size which is characteristic of superparamagnetism. The hysteresis curves show reduction in saturation magnetization in the case of nanoparticles as compared to their bulk counterpart, which have been explained on the basis that the magnetic moments in the surface layers of a nanoparticle are in a state of frozen disorder. However the saturation magnetization increases with particle size, which is the characteristic property of single domain superparamagnetic particles.

  11. Influence of pH on the structural and magnetic behavior of cobalt ferrite synthesized by sol-gel auto-combustion

    NASA Astrophysics Data System (ADS)

    Kakade, S. G.; Kambale, R. C.; Kolekar, Y. D.

    2015-06-01

    Cobalt ferrite (CoFe2O4) shown to be promising candidate for applications such as high-density magnetic recording, enhanced memory storage, magnetic fluids and catalysts. Utility of ferrite nanoparticles depends on its size, dispersibility in solutions, and magnetic properties. We have investigated the structural properties of synthesized cobalt ferrite nanoparticles synthesized by sol gel auto combustion for uncontrolled, acidic, neutral and basic pH values. X-ray diffraction (XRD) study confirms the cubic spinel phase formation with lattice constant 8.38 Å. In this study, we have optimized the pH value to synthesize homogenous cobalt ferrite nanoparticles with enhanced magnetic behavior. The surface morphology has been investigated by employing SEM images and the confirmation of spinel ferrite was also supported by using IR spectroscopy. Magnetic measurements for CoFe2O4 compositions (with pH <1, pH = 3, 7, 10) were investigated using VSM measurements.

  12. Magnetic response of polycrystalline YBaCo4O7+? synthesized through the physical and chemical route: The role of phase inhomogeneities

    NASA Astrophysics Data System (ADS)

    Vallejos, E.; Galeano, V.; Gómez, L.; Izquierdo, J. L.; Montoya, J. F.; Mera, J.; Córdoba, C.; Gómez, A.; Paucar, C.; Morán, O.

    2014-06-01

    Polycrystalline YBaCo4O7+? samples were obtained through a standard solid state reaction, and their structural, morphological, electrical, and magnetic properties are carefully studied. The X-ray powder diffraction (XRD) patterns showed reflections of a pure hexagonal structure (space group P63mc) with lattice parameters being very close to those reported in the literature. Although XRD analysis showed that the main phase present is 114, the presence of secondary phases could not be ruled out based solely on the XRD characterization. Indeed, sensitive SQUID magnetic measurements showed that the samples were affected by very small quantities of the 112 phase (YBaCo2O5.5), which typically manifests itself through a conspicuous increase in the magnetization at~300 K. The results achieved corroborated the predictions concerning the difficulty of stabilizing the 114 phase when synthesized via the standard solid-state reaction. With this in mind, we next attempted to obtain the compound with improved phase purity. In so doing, the YBaCo4O7+? compound was synthesized through a wet chemistry method based on a citrates route. The XRD patterns recorded for these samples revealed well-defined peaks corresponding to a pure hexagonal structure. More interestingly, SQUID measurements show no sign of features in the M(T) curve at temperatures as low as~80 K. This result was consistent with the magnetic behavior observed in YBaCo4O7+? single-crystals. At temperatures below~80 K, a clear feature was observed which seemed to correlate with a transition into an antiferromagnetic state. Isothermal magnetization recorded at 70 K showed that field-induced effects manifested themselves through the appearance of a ferromagnetic-like component. This ferromagnetic component may arise from spin canting of the underlying antiferromagnetic state or through field-induced structural transition (at least at local scale). Although a definitive interpretation of the in-field behavior from magnetization data alone is difficult because of the unknown role of the yttrium ion, the results achieved suggest that the magnetic behavior observed in members of the R-114 family is not necessarily linked to the moment of the rare-earth ion, as in case of YBaCo4O7+?, since the yttrium ion is not magnetic. Beyond this important finding, the experimental results reported in the present paper demonstrate that the tested chemical route is suitable for synthesizing complex, single-phase oxides, such as the YBaCo4O7+? cobaltate. The success in synthesizing high-purity YBaCo4O7+? allows one to subtract parasitic effects from the intrinsic magnetic behavior of this challenging system.

  13. Magnetic attachment mechanism

    NASA Technical Reports Server (NTRS)

    Harwell, William D. (Inventor); Wu, Mitchell B. (Inventor)

    1990-01-01

    A magnetic attachment mechanism adapted for interfacing with the manipulator arm (11) of a remote manipulator system and comprising a pair of permanent magnets (31,32) of rare earth material which are arranged in a stator-rotor relationship. The rotor magnet (32), is journalled for rotation about its longitudinal axis between pole plates (35,36) of the stator magnet (31), each of which includes an adhering surface (35a,36a). In a first rotary position corresponding to the ON condition, each of the poles of the rotor magnet (32) is closely adjacent a stator magnet pole plate of like polarity whereby the respective magnet fields are additive for producing a strong magnetic field emanating from the adhering surfaces (35a,36a) for attracting a ferrous magnetic plate 20, or the like, affixed to the payload (20 or 50). When the rotor magnet (32) is rotated to a second position corresponding to the OFF condition, each of the poles of the rotor magnet (31) is disposed closely adjacent a pole plate of unlike polarity whereby the magnetic fields of the magnets are in cancelling relationship at the adhering surfaces (35a,36a) which permits the release of a payload. An actuator (51 or 70) for selectively rotating the rotor magnet (32) between the ON and OFF positions is provided for interfacing and connecting the magnetic attachment mechanism with a manipulator arm. For effecting an optimal rigidized attachment the payload is provided with guides (91,92) cooperable with guides (96,16,17) on the housing of the mechanism for directing adhering surfaces (35a,36a) of the polar plates to the ferrous plate (20).

  14. Magnetic hyperthermia with hard-magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Kashevsky, Bronislav E.; Kashevsky, Sergey B.; Korenkov, Victor S.; Istomin, Yuri P.; Terpinskaya, Tatyana I.; Ulashchik, Vladimir S.

    2015-04-01

    Recent clinical trials of magnetic hyperthermia have proved, and even hardened, the Ankinson-Brezovich restriction as upon magnetic field conditions applicable to any site of human body. Subject to this restriction, which is harshly violated in numerous laboratory and small animal studies, magnetic hyperthermia can relay on rather moderate heat source, so that optimization of the whole hyperthermia system remains, after all, the basic problem predetermining its clinical perspectives. We present short account of our complex (theoretical, laboratory and small animal) studies to demonstrate that such perspectives should be related with the hyperthermia system based on hard-magnetic (Stoner-Wohlfarth type) nanoparticles and strong low-frequency fields rather than with superparamagnetic (Brownian or Neél) nanoparticles and weak high-frequency fields. This conclusion is backed by an analytical evaluation of the maximum absorption rates possible under the field restriction in the ideal hard-magnetic (Stoner-Wohlarth) and the ideal superparamagnetic (single relaxation time) systems, by theoretical and experimental studies of the dynamic magnetic hysteresis in suspensions of movable hard-magnetic particles, by producing nanoparticles with adjusted coercivity and suspensions of such particles capable of effective energy absorption and intratumoral penetration, and finally, by successful treatment of a mice model tumor under field conditions acceptable for whole human body.

  15. Effect of grain size on the magnetic properties of superparamagnetic Ni 0.5Zn 0.5Fe 2O 4 nanoparticles by co-precipitation process

    NASA Astrophysics Data System (ADS)

    Chen, D. G.; Tang, X. G.; Wu, J. B.; Zhang, W.; Liu, Q. X.; Jiang, Y. P.

    2011-06-01

    Ni 0.5Zn 0.5Fe 2O 4 (NZFO) spinel-type nanoparticles were directly fabricated by the chemical co-precipitation process using metal nitrate and acetate as precursors since nitrogen and carbon would be taken away in the forms of oxynitride and oxycarbide, respectively, after the precursors were annealed and then investigated in detail by employing X-ray diffraction (XRD), magnetic measurement and Raman spectroscopy. XRD analysis indicates that the as-prepared nanocrystals are all of a pure cubic spinel structure with their sizes ranging from 20.8 to 53.3 nm, as well as peaks of some samples shifting to lower angles due to lattice expansion. Calculations from the derived XRD data indicate that the activation energy is 30.83 kJ/mol. The magnetic measurements show that these samples are superparamagnetic. The saturation magnetization increases with annealing temperature, which may be explained by super-exchange interactions of Fe ions occurring at A- and B-sites. The variation of coercivity with particle size is interpreted on the basis of domain structure and crystal anisotropy. Furthermore, these nanoparticles exhibit a redshift phenomenon at lower temperatures seen in the Raman spectra, which could be related to ionic substitution.

  16. Creation of high-density and low-defect single-layer film of magnetic nanoparticles by the method of interfacial molecular films.

    PubMed

    Fujimori, Atsuhiro; Ohmura, Kyohei; Honda, Nanami; Kakizaki, Koichi

    2015-03-17

    A technique to solubilize fine magnetic inorganic particles in general organic solvents is proposed via surfaces modification by long-chain carboxylic acids. This organic modification should overcome the relatively weak van der Waals interactions between the nanoparticles, allowing the formation of ordered arrangements of the modified Fe3O4 and CoFe2O4 materials. Using nanodispersions of these organo-modified magnetic nanoparticles as "spreading solutions", Langmuir monolayers of these particles were formed. Multiparticle layered structures were constructed by the Langmuir-Blodgett (LB) technique. The fabrication of single- and multiparticle layers of organo-modified magnetic nanoparticles was investigated using surface pressure-area (?-A) isotherms, out-of-plane X-ray diffraction (XRD), in-plane XRD, and atomic force microscopy (AFM). The out-of-plane XRD profile of a single-particle layer of organo-modified Fe3O4 clearly showed a sharp peak which was attributed to the distance between Fe3O4 layers along the c-axis. The AFM image of single-particle layer of organo-modified CoFe2O4 revealed integrated particle organization with a uniform height; these aggregated particles formed large two-dimensional crystals. For both nanoparticle species, regular periodic structures along the c-axis and high-density single-particle layers were produced via the Langmuir and LB techniques. PMID:25727135

  17. Structural, electronic and magnetic properties of Mo (4d)-based complex perovskites Ba2MMoO6 (M=Cr and Fe)

    NASA Astrophysics Data System (ADS)

    Musa Saad H.-E., M.; El-Hagary, M.

    2014-06-01

    We report a study of crystallographic parameters of the Mo-based complex perovskites Ba2MMoO6 (M=Cr and Fe) obtained from analysis of X-ray diffraction (XRD) data and the electronic and magnetic properties prediction using the magnetic measurements and the full-potential linearized muffin-tin orbitals within the plane-wave approximation (LMTO-PLW). The Ba2MMoO6 materials were prepared by the solid state reaction method. XRD analysis reveals that Ba2MMoO6 crystalline in a cubic structure (space group Fm-3m) with lattice parameters (a=8.013 Å) for M=Cr and (a=8.061 Å) for M=Fe. XRD results present a matching of 98% with the theoretical results. The densities of states were calculated using the local spin density approximation (LSDA) and LSDA+U methods. LDOS results show a half-metallic-ferrimagnetic ground state for Ba2MMoO6, which is in majority due to the 4d-t2g and 3d-t2g characters. The structural, electronic and magnetic calculation results are in excellent agreement with the experimental and previous theoretical results.

  18. Permanent-Magnet Meissner Bearing

    NASA Technical Reports Server (NTRS)

    Robertson, Glen A.

    1994-01-01

    Permanent-magnet meissner bearing features inherently stable, self-centering conical configuration. Bearing made stiffer or less stiff by selection of magnets, springs, and spring adjustments. Cylindrical permanent magnets with axial magnetization stacked coaxially on rotor with alternating polarity. Typically, rare-earth magnets used. Magnets machined and fitted together to form conical outer surface.

  19. Rare earth permanent magnets

    SciTech Connect

    Major-Sosias, M.A.

    1993-10-01

    Permanent magnets were discovered centuries ago from what was known as {open_quotes}lodestone{close_quotes}, a rock containing large quantities of the iron-bearing mineral magnetite (Fe{sub 3}O{sub 4}). The compass was the first technological use for permanent magnetic materials; it was used extensively for navigational purposes by the fifteenth century. During the twentieth century, as new applications for permanent magnets were developed, interest and research in permanent magnetic materials soared. Four major types of permanent magnets have been developed since the turn of the century.

  20. Magnetically attached sputter targets

    DOEpatents

    Makowiecki, D.M.; McKernan, M.A.

    1994-02-15

    An improved method and assembly for attaching sputtering targets to cathode assemblies of sputtering systems which includes a magnetically permeable material is described. The magnetically permeable material is imbedded in a target base that is brazed, welded, or soldered to the sputter target, or is mechanically retained in the target material. Target attachment to the cathode is achieved by virtue of the permanent magnets and/or the pole pieces in the cathode assembly that create magnetic flux lines adjacent to the backing plate, which strongly attract the magnetically permeable material in the target assembly. 11 figures.

  1. Switchable molecular magnets

    PubMed Central

    SATO, Osamu

    2012-01-01

    Various molecular magnetic compounds whose magnetic properties can be controlled by external stimuli have been developed, including electrochemically, photochemically, and chemically tunable bulk magnets as well as a phototunable antiferromagnetic phase of single chain magnet. In addition, we present tunable paramagnetic mononuclear complexes ranging from spin crossover complexes and valence tautomeric complexes to Co complexes in which orbital angular momentum can be switched. Furthermore, we recently developed several switchable clusters and one-dimensional coordination polymers. The switching of magnetic properties can be achieved by modulating metals, ligands, and molecules/ions in the second sphere of the complexes. PMID:22728438

  2. Magnetically attached sputter targets

    DOEpatents

    Makowiecki, Daniel M. (Livermore, CA); McKernan, Mark A. (Livermore, CA)

    1994-01-01

    An improved method and assembly for attaching sputtering targets to cathode assemblies of sputtering systems which includes a magnetically permeable material. The magnetically permeable material is imbedded in a target base that is brazed, welded, or soldered to the sputter target, or is mechanically retained in the target material. Target attachment to the cathode is achieved by virtue of the permanent magnets and/or the pole pieces in the cathode assembly that create magnetic flux lines adjacent to the backing plate, which strongly attract the magnetically permeable material in the target assembly.

  3. In-situ magnetization of NdFeB magnets for permanent magnet machines

    SciTech Connect

    Chang, L.; Eastham, T.R.; Dawson, G.E. )

    1991-09-01

    In-situ magnetizers are needed to facilitate the assembly of permanent magnet machines and to remagnetize the magnets after weakening due to a fault condition. The air-core magnetizer in association with the silicon steel lamination structure of the rotor has advantages over its iron-core counterpart. This novel method has been used to magnetize the NdFeB magnets in a 30-hp permanent magnet synchronous motor. The magnetizing capability for different magnetizer geometries was investigated for the magnetization of NdFeB material. The design, testing, and operation of this magnetizer are reported in this paper.

  4. Preparation of Pd/Fe3O4 nanoparticles by use of Euphorbia stracheyi Boiss root extract: A magnetically recoverable catalyst for one-pot reductive amination of aldehydes at room temperature.

    PubMed

    Nasrollahzadeh, Mahmoud; Sajadi, S Mohammad

    2016-02-15

    We describe a method for supporting palladium nanoparticles on magnetic nanoparticles using Euphorbia stracheyi Boiss root extract as the natural source of reducing and stabilizing agent. The progress of the reaction was monitored using UV-visible spectroscopy. The nanocatalyst was characterized by FE-SEM, TEM, XRD, EDS, FT-IR spectroscopy and ICP. The nanocatalyst was applied as an efficient, magnetically recoverable, highly reusable and heterogeneous catalyst for one-pot reductive amination of aldehydes at room temperature. The nanocatalyst was easily recovered by applying an external magnet and reused several times without considerable loss of activity. PMID:26615511

  5. Magnetism: Principles and Applications

    NASA Astrophysics Data System (ADS)

    Craik, Derek J.

    2003-09-01

    If you are studying physics, chemistry, materials science, electrical engineering, information technology or medicine, then you'll know that understanding magnetism is fundamental to success in your studies and here is the key to unlocking the mysteries of magnetism....... You can: obtain a simple overview of magnetism, including the roles of B and H, resonances and special techniques take full advantage of modern magnets with a wealth of expressions for fields and forces develop realistic general design programmes using isoparametric finite elements study the subtleties of the general theory of magnetic moments and their dynamics follow the development of outstanding materials appreciate how magnetism encompasses topics as diverse as rock magnetism, chemical reaction rates, biological compasses, medical therapies, superconductivity and levitation understand the basis and remarkable achievements of magnetic resonance imaging In his new book, Magnetism, Derek Craik throws light on the principles and applications of this fascinating subject. From formulae for calculating fields to quantum theory, the secrets of magnetism are exposed, ensuring that whether you are a chemist or engineer, physicist, medic or materials scientist Magnetism is the book for our course.

  6. Magnetic Storms in Brazil

    NASA Astrophysics Data System (ADS)

    Pinheiro, K.; Siqueira, F.

    2013-05-01

    Magnetic storms result from atypical processes generated in the Sun, the interaction between the solar wind and the Earth's magnetosphere and the energization of particles in the magnetosphere. As consequence, magnetic storms may cause problems on radio communication, in satellites, GPS imprecision and induce geomagnetic induced currents that my cause saturation and damage of transformers. Magnetic storms are measured in magnetic observatories, where it is possible to observe large variations in the horizontal magnetic field. These variations are most visible in equatorial or low-latitude magnetograms. In this work, we use low latitude dataset from three magnetic observatories in Brazil: Vassouras (Rio de Janeiro) that presents data since 1915, Tatuoca (Pará) since 1957 and data from a new magnetic observatory that was installed in Pantanal (Brazil) on the 22nd October 2012. Vassouras and Pantanal observatories are in the region of the South Atlantic Magnetic Anomaly. External magnetic field interactions in this region are poorly known due to the lack of magnetic data. Tatuoca observatory is located in another important geomagnetic region: the equatorial electrojet. In this work we present the data processing of the recent geomagnetic time series in Pantanal Observatory and its comparison with Vassouras and Tatuoca observatories in Brazil. We analyse the main characteristics of magnetic storms in these observatories, as the sudden commencement and their duration.

  7. Superconducting multipole corrector magnet

    SciTech Connect

    Kashikhin, Vladimir; /Fermilab

    2004-10-01

    A novel concept of superconducting multipole corrector magnet is discussed. This magnet assembled from 12 identical racetrack type coils and can generate any combination of dipole, quadrupole and sextupole magnetic fields. The coil groups are powered from separate power supplies. In the case of normal dipole, quadrupole and sextupole fields the total field is symmetrical relatively the magnet median plane and there are only five powered separately coil groups. This type multipole corrector magnet was proposed for BTeV, Fermilab project and has following advantages: universal configuration, simple manufacturing and high mechanical stability. The results of magnetic design including the field quality and magnetic forces in comparison with known shell type superconducting correctors are presented.

  8. Magnetic bearing and motor

    NASA Technical Reports Server (NTRS)

    Studer, Philip A. (Inventor)

    1983-01-01

    A magnetic bearing assembly (10) has an intermediate rotatable section (33) having an outer cylindrical member (30) coaxially suspended by a torsion wire (72) around an axially polarized cylindrical magnet (32). Axial alignment between the pole faces (40-43) of the intermediate section (33) and end surfaces (50-53) of opposed end bells (20, 22) provides a path of least reluctance across intervening air gaps (60-63) for the magnetic flux emanating from magnet (32). Radial dislocation increases the reluctance and creates a radial restoring force. Substitution of radially polarized magnets 107 fixed to a magnetically permeable cylinder (32') and insertion of pairs of armature coil windings (109-112) between the cylinder pair (33') provides an integral magnetic bearing and torsion motor (100) able to provide arcuately limited rotational drive.

  9. Cold plasma treatment of magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Wang, Ke

    This thesis investigates the application of cold plasma to remove the oleic acid bonded on magnetic nanoparticles: SmCo5 nanoflakes prepared via surfactant assisted high energy ball milling and CoFe2O 4 nanoparticles prepared via chemical synthesis. Oleic acid molecules bonded on nanoparticles are in the carboxylate form which could not be washed away by organic solvents in ultrasonic bath; only free oleic acid molecules left on the nanoparticle surface after ball milling can be washed away through ultrasonic bath. High temperature annealing method works for removing oleic acid but nanoparticles would be damaged because of oxidation and decomposition. The RF cold plasma has advantages over above methods as the plasma temperature is typically around room temperature, and the energetic ions could strike away carboxylate molecules bonded on the surface of nanoparticles without changing the surface chemistry. Powder X-ray diffraction (XRD) was performed to see if there was phase transformation, decomposition during plasma treatment. The content change of oleic acid molecules on the nanoparticles surface was confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR).

  10. Synthesis and high-efficiency methylene blue adsorption of magnetic PAA/MnFe2O4 nanocomposites

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Ding, Zui; Cai, Minhan; Jian, Haitao; Zeng, Zhiqiao; Li, Feng; Liu, J. Ping

    2015-08-01

    MnFe2O4 nanoparticles and polyacrylic acid PAA/MnFe2O4 nanocomposites were synthesized by a hydrothermal method and ultrasonic mixing process. The obtained materials were characterized by XRD, FTIR, SEM, TEM, and VSM. XRD patterns indicate that the synthesized MnFe2O4 nanoparticles have a single cubic spinel phase. SEM images confirm the existence of three types of basic morphology of MnFe2O4 nanoparticles: octahedral, flower-like, and plate-like particles. High saturation magnetization Ms (up to 74.6 emu/g) of the as-synthesized MnFe2O4 nanoparticles was obtained. Experiments demonstrate that the variation of the hydrothermal reaction time does not remarkably affect the magnetic properties of MnFe2O4 nanoparticles. In PAA/MnFe2O4 nanocomposites, the coating of PAA leads to a slight decrease in magnetization of MnFe2O4 nanoparticles. Additionally, PAA coating greatly enhances the adsorption properties of MnFe2O4 nanoparticles for Methylene Blue (MB) dye. Especially, the removal efficiency reaches 96.3%. This research indicates that the as-synthesized PAA/MnFe2O4 nanocomposites exhibit excellent magnetic properties and can be taken as a promising adsorbent for removal of MB dye in industrial scale.

  11. Influence of rare-earth ions on the structure and magnetic properties of barium W-type hexaferrite

    NASA Astrophysics Data System (ADS)

    Ahmed, M. A.; Okasha, N.; Kershi, R. M.

    Barium W-type hexaferrite with composition Ba 0.95R 0.05Mg 0.5Zn 0.5CoFe 16O 27 where R=Y, Er, Ho, Sm, Nd, Gd, and Ce ions has been prepared by the double-sintering ceramic technique. Structure of the prepared samples has been characterized by the X-ray diffraction (XRD) technique. The XRD patterns at room temperature show the presence of secondary phase with the intensity of the secondary phase increasing with increasing ionic radius of the rare earth (RE) ions. The variation of the magnetic susceptibility ( ?M) with temperature in the range 300-750 K at different magnetic field intensities (1280, 1733 and 2160 Oe) was studied by using Faraday's method. The results show that the Curie temperature ( TC) increases regularly with increasing RE ionic radius then decreases again, after which it reaches maximum value at Sm ion of radius ?1.04 Å. This behavior was explained on the basis of the changes in Fe 3+-O-Fe 3+ superexchange interaction. The effective magnetic moment ?eff. of the investigated samples was discussed in view of varying the RE element as well as the magnetization of different sublattices.

  12. Surface modified magnetic nanoparticles as efficient and green sorbents: Synthesis, characterization, and application for the removal of anionic dye

    NASA Astrophysics Data System (ADS)

    Rajabi, Hamid Reza; Arjmand, Hooman; Hoseini, S. Jafar; Nasrabadi, Hasan

    2015-11-01

    The object of this study was to evaluate the removal efficiency of sunset yellow (SY) anionic dye from aqueous solutions by using new surface modified iron oxide magnetic nanoparticles (MNPs). Pure Fe3O4 MNPs were synthesized and then functionalized by aminopropyltriethoxysilane (APTES), through a chemical precipitation method. Characterization of the prepared MNP adsorbents was performed by furrier transform infrared (FT-IR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and transmission electron microscopy (TEM). According to XRD and TEM results, average size of the magnetic Fe3O4/APTES NPs was estimated to be around 12 nm. The prepared magnetic adsorbent can be well dispersed in the water and easily separated magnetically from the medium after loaded with adsorbate. In the adsorption process, the effect of main experimental parameters such as pH of dye solution, initial concentration of SY dye, reaction time, and amount of MNP adsorbent on the removal of SY were studied and optimized. The small amount of this adsorbent (10 mg) is applicable for the removal of high concentrations of SY dye in reasonable time (17 min), at pH 3.1. Additionally, the adsorption studies show that the Langmuir model is a suitable model to explain the experimental data with high correlation coefficient.

  13. Structural Changes and Thermal Stability of Charged LiNi1/3Co1/3Mn1/3O2 Cathode Material for Li-ion Batteries Studied by Time-Resolved XRD

    SciTech Connect

    Nam, K.; Yoon, W; Yang, X

    2009-01-01

    Structural changes and their relationship with thermal stability of charged Li0.33Ni1/3Co1/3Mn1/3O2 cathode samples have been studied using time-resolved X-ray diffraction (TR-XRD) in a wide temperature from 25 to 600 C with and without the presence of electrolyte in comparison with Li0.27Ni0.8Co0.15Al0.05O2 cathodes. Unique phase transition behavior during heating is found for the Li0.33Ni1/3Co1/3Mn1/3O2 cathode samples: when no electrolyte is present, the initial layered structure changes first to a LiM2O4-type spinel, and then to a M3O4-type spinel and remains in this structure up to 600 C. For the Li0.33Ni1/3Co1/3Mn1/3O2 cathode sample with electrolyte, additional phase transition from the M3O4-type spinel to the MO-type rock salt phase takes place from about 400 to 441 C together with the formation of metallic phase at about 460 C. The major difference between this type of phase transitions and that for Li0.27Ni0.8Co0.15Al0.05O2 in the presence of electrolyte is the delayed phase transition from the spinel-type to the rock salt-type phase by stretching the temperature range of spinel phases from about 20 to 140 C. This unique behavior is considered as the key factor of the better thermal stability of the Li1-xNi1/3Co1/3Mn1/3O2 cathode materials.

  14. Magnetic solid-phase extraction of protein with deep eutectic solvent immobilized magnetic graphene oxide nanoparticles.

    PubMed

    Xu, Kaijia; Wang, Yuzhi; Ding, Xueqin; Huang, Yanhua; Li, Na; Wen, Qian

    2016-02-01

    As a new type of green solvent, four kinds of choline chloride (ChCl)-based deep eutectic solvents (DESs) have been synthesized, and then a core-shell structure magnetic graphene oxide (Fe3O4-NH2@GO) nanoparticles have been prepared and coated with the ChCl-based DESs. Magnetic solid-phase extraction (MSPE) based Fe3O4-NH2@GO@DES was studied for the first time for the extraction of proteins. The characteristic results of vibrating sample magnetometer (VSM), X-ray diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), thermal gravimetric analysis (TGA) and field emission scanning electron microscopy (FESEM) indicated the successful preparation of Fe3O4-NH2@GO@DES. The concentrations of proteins in studies were determined by a UV-vis spectrophotometer. The advantages of Fe3O4-NH2@GO@DES in protein extraction were compared with Fe3O4-NH2@GO and Fe3O4-NH2, and Fe3O4-NH2@GO@ChCl-glycerol was selected as the suitable extraction solvent. The influence factors of the extraction process such as the pH value, the temperature, the extraction time, the concentration of protein and the amount of Fe3O4-NH2@GO@ChCl-glycerol were evaluated. Desorption experimental result showed 98.73% of BSA could be eluted from the solid extractant with 0.1mol/L Na2HPO4 solution contained 1mol/L NaCl. Besides, the conformation of BSA was not changed during the elution by the investigation of circular dichromism (CD) spectra. Furthermore, the analysis of real sample demonstrated that the prepared magnetic nanoparticles did have extraction ability on proteins in bovine whole blood. PMID:26653436

  15. Development of Rare-Earth Free Mn-Al Permanent Magnet Employing Powder Metallurgy Route

    NASA Astrophysics Data System (ADS)

    Singh, N.; Shyam, R.; Upadhyay, N. K.; Dhar, A.

    2015-02-01

    Most widely used high-performance permanent magnets are currently based on intermetallics of rare-earths in combination with Fe and Co. Rare-earth elements required for these magnets are getting expensive by the day. Consequently, there is a thrust worldwide to develop economical rare-earth free permanent magnets. It is acknowledged that the phase in Mn-Al alloys possesses magnetic properties without the presence of ferromagnetic elements such as Fe, Co, and Ni. In the present study, we report the synthesis of magnetic phase of Mn54Al46 alloy synthesized using mechanical alloying followed by solutionizing and annealing to obtain the desired magnetic phase. It is well known that Al dissolves partially in Mn matrix hence supersaturated solid solution of Mn54Al46 alloy powder was obtained by mechanical alloying using a planetary high-energy ball mill. For this purpose elemental Mn and Al powders were ball-milled in Argon atmosphere at 400 rpm using stainless steel bowl with ball to powder ratio of 15:1. These mechanically alloyed Mn54Al46 powders were then consolidated using spark plasma sintering at 550°C for 20 min. followed by solution treatment at 1050°C for 5 hrs and then water quenched to retain high temperature phase. Subsequently, the Mn54Al46 samples were annealed in the temperature range 450°C-650°C to obtain the magnetic phase. These samples were characterized by XRD and SEM and the magnetic properties were measured using a vibrating sample magnetometer (VSM). It was observed that the magnetization and coercivity of MnAl magnets exhibited strong dependence on annealing temperature and annealing time.

  16. Magnetic Propeller for Uniform Magnetic Field Levitation

    E-print Network

    Krinker, Mark

    2008-01-01

    Three new approaches to generating thrust in uniform magnetic fields are proposed. The first direction is based on employing Lorentz force acting on partial magnetically shielded 8-shaped loop with current in external magnetic field, whereby a net force rather than a torque origins. Another approach, called a Virtual Wire System, is based on creating a magnetic field having an energetic symmetry (a virtual wire), with further superposition of external field. The external field breaks the symmetry causing origination of a net force. Unlike a wire with current, having radial energetic symmetry, the symmetry of the Virtual Wire System is closer to an axial wire. The third approach refers to the first two. It is based on creation of developed surface system, comprising the elements of the first two types. The developed surface approach is a way to drastically increase a thrust-to-weight ratio. The conducted experiments have confirmed feasibility of the proposed approaches.

  17. Magnetic Propeller for Uniform Magnetic Field Levitation

    E-print Network

    Mark Krinker; Alexander Bolonkin

    2008-07-12

    Three new approaches to generating thrust in uniform magnetic fields are proposed. The first direction is based on employing Lorentz force acting on partial magnetically shielded 8-shaped loop with current in external magnetic field, whereby a net force rather than a torque origins. Another approach, called a Virtual Wire System, is based on creating a magnetic field having an energetic symmetry (a virtual wire), with further superposition of external field. The external field breaks the symmetry causing origination of a net force. Unlike a wire with current, having radial energetic symmetry, the symmetry of the Virtual Wire System is closer to an axial wire. The third approach refers to the first two. It is based on creation of developed surface system, comprising the elements of the first two types. The developed surface approach is a way to drastically increase a thrust-to-weight ratio. The conducted experiments have confirmed feasibility of the proposed approaches.

  18. Injection and extraction magnets: kicker magnets

    E-print Network

    Barnes, M J; Fowler, T; Senaj, V; Sermeus, L

    2010-01-01

    Each stage of an accelerator system has a limited dynamic range and therefore a chain of stages is required to reach high energy. A combination of septa and kicker magnets is frequently used to inject and extract beam from each stage. The kicker magnets typically produce rectangular field pulses with fast rise- and/or fall-times, however, the field strength is relatively low. To compensate for their relatively low field strength, the kicker magnets are generally combined with electromagnetic septa. The septa provide relatively strong field strength but are either DC or slow pulsed. This paper discusses injection and extraction systems with particular emphasis on the hardware required for the kicker magnet.

  19. Cr-substituted Ni-Zn ferrites via oxalate decomposition. Structural, electrical and magnetic properties

    NASA Astrophysics Data System (ADS)

    Gabal, M. A.; Al Angari, Y. M.; Al-Agel, F. A.

    2015-10-01

    A series of Cr-substituted Ni-Zn ferrites; Ni0.8Zn0.2CrxFe2-xO4 (x=0.0-1.0) were prepared via oxalate decomposition route to characterize the effect of Cr-substitution on structural, magnetic and electrical properties. The prepared powders were characterized using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and transmission electron microscopy (TEM). XRD indicated single-phase cubic ferrites. The lattice parameters (aExp) exhibited a gradual decrease with increasing chromium, attributed to the smaller ionic radii of Cr3+ substituent. According to the obtained structural data, an appropriate cation distribution was suggested and fortified through FT-IR spectroscopy besides magnetic and electrical measurements. TEM image showed agglomerated cubic crystals with an average size of about 20 nm. Vibrating sample magnetometer (VSM) measurements indicated minimal hysteresis characteristic for soft magnetic material. The decrease in saturation magnetization (Ms) with Cr-substitution was discussed in view of Neel's two sub-lattice model. The change in the coercivity with Cr-content was discussed in view of estimated cation distribution and magnetization values. The obvious fall in the Curie temperature, estimated from molar susceptibility measurements, with increasing Cr-concentrations was assigned to the gradual replacement of Fe3+ ions on the octahedral sites by paramagnetic Cr3+ ions. ac-conductivity as a function of both frequency and absolute temperature exhibited a semi-conducting behavior. The decrease in conductivity with increasing Cr-content was attributed to the preferential occupation of Cr3+ ions by octahedral sites which replacing Fe3+ ions and limiting Fe2+-Fe3+ conduction.

  20. Structural and magnetic properties of conventional and microwave treated Ni-Zr doped barium strontium hexaferrite

    SciTech Connect

    Kanagesan, S.; Jesurani, S.; Department of Physics, Jeyaraj Annapackium College for Women, Periyakulam 625601, Tamil Nadu ; Velmurugan, R.; Prabu, S.; Kalaivani, T.

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Saturation magnetization increases whereas the coercivity decreases. Black-Right-Pointing-Pointer The transition from hard phase to soft phase. Black-Right-Pointing-Pointer Therefore, it is used for high-density magnetic recording applications. -- Abstract: M-type hexaferrites of component B{sub 0.5}Sr{sub 0.5}Fe{sub 12-2x}Ni{sub x}Zr{sub x}O{sub 19} were investigated. The XRD patterns show single phase of the magnetoplumbite barium strontium ferrite and no other phases were present. Significant increase in line broadening of the XRD patterns was observed indicating a decrease of grain size. The samples exhibit well defined crystallization; all of them are hexagonal platelet grains. As the substitution level increased x = 0.2-0.8 mol%, the grains are agglomerated and the average diameter increased. The H{sub c} decreases remarkably with increasing Ni and Zr ions content. It was found that the particle size could be effectively decreased and coercivity H{sub c} could easily be controlled by varying the concentration (x) without significantly decreasing saturation magnetization. In particular, Ba{sub 0.5}Sr{sub 0.5}Fe{sub 12-2x}Ni{sub x}Zr{sub x}O{sub 19} with x = 0.2, 0.4, 0.6, 0.8 mol% has suitable magnetic characteristics with particle size small enough for high-density magnetic recording applications.

  1. Magnetic force microscopy

    PubMed Central

    Passeri, Daniele; Dong, Chunhua; Reggente, Melania; Angeloni, Livia; Barteri, Mario; Scaramuzzo, Francesca A; De Angelis, Francesca; Marinelli, Fiorenzo; Antonelli, Flavia; Rinaldi, Federica; Marianecci, Carlotta; Carafa, Maria; Sorbo, Angela; Sordi, Daniela; Arends, Isabel WCE; Rossi, Marco

    2014-01-01

    Magnetic force microscopy (MFM) is an atomic force microscopy (AFM) based technique in which an AFM tip with a magnetic coating is used to probe local magnetic fields with the typical AFM spatial resolution, thus allowing one to acquire images reflecting the local magnetic properties of the samples at the nanoscale. Being a well established tool for the characterization of magnetic recording media, superconductors and magnetic nanomaterials, MFM is finding constantly increasing application in the study of magnetic properties of materials and systems of biological and biomedical interest. After reviewing these latter applications, three case studies are presented in which MFM is used to characterize: (i) magnetoferritin synthesized using apoferritin as molecular reactor; (ii) magnetic nanoparticles loaded niosomes to be used as nanocarriers for drug delivery; (iii) leukemic cells labeled using folic acid-coated core-shell superparamagnetic nanoparticles in order to exploit the presence of folate receptors on the cell membrane surface. In these examples, MFM data are quantitatively analyzed evidencing the limits of the simple analytical models currently used. Provided that suitable models are used to simulate the MFM response, MFM can be used to evaluate the magnetic momentum of the core of magnetoferritin, the iron entrapment efficiency in single vesicles, or the uptake of magnetic nanoparticles into cells. PMID:25050758

  2. Magnetic bearing and motor

    NASA Technical Reports Server (NTRS)

    Studer, P. A. (inventor)

    1983-01-01

    A magnetic bearing for passively suspending a rotatable element subjected to axial and radial thrust forces is disclosed. The magnetic bearing employs a taut wire stretched along the longitudinal axis of the bearing between opposed end pieces and an intermediate magnetic section. The intermediate section is segmented to provide oppositely directed magnetic flux paths between the end pieces and may include either an axially polarized magnets interposed between the segments. The end pieces, separated from the intermediate section by air gaps, control distribution of magnetic flux between the intermediate section segments. Coaxial alignment of the end pieces with the intermediate section minimizes magnetic reluctance in the flux paths endowing the bearing with self-centering characteristics when subjected to radial loads. In an alternative embodiment, pairs of oppositely wound armature coils are concentrically interposed between segments of the intermediate section in concentric arcs adjacent to radially polarized magnets to equip a magnetic bearing as a torsion drive motor. The magnetic suspension bearing disclosed provides long term reliability without maintenance with application to long term space missions such as the VISSR/VAS scanning mirror instrument in the GOES program.

  3. Magnetism in Medicine

    NASA Astrophysics Data System (ADS)

    Schenck, John

    2000-03-01

    For centuries physicians, scientists and others have postulated an important role, either as a cause of disease or as a mode of therapy, for magnetism in medicine. Although there is a straightforward role in the removal of magnetic foreign bodies, the majority of the proposed magnetic applications have been controversial and have often been attributed by mainstream practitioners to fraud, quackery or self-deception. Calculations indicate that many of the proposed methods of action, e.g., the field-induced alignment of water molecules or alterations in blood flow, are of negligible magnitude. Nonetheless, even at the present time, the use of small surface magnets (magnetotherapy) to treat arthritis and similar diseases is a widespread form of folk medicine and is said to involve sales of approximately one billion dollars per year. Another medical application of magnetism associated with Mesmer and others (eventually known as animal magnetism) has been discredited, but has had a culturally significant role in the development of hypnotism and as one of the sources of modern psychotherapy. Over the last two decades, in marked contrast to previous applications of magnetism to medicine, magnetic resonance imaging or MRI, has become firmly established as a clinical diagnostic tool. MRI permits the non-invasive study of subtle biological processes in intact, living organisms and approximately 150,000,000 diagnostic studies have been performed since its clinical introduction in the early 1980s. The dramatically swift and widespread acceptance of MRI was made possible by scientific and engineering advances - including nuclear magnetic resonance, computer technology and whole-body-sized, high field superconducting magnets - in the decades following World War Two. Although presently used much less than MRI, additional applications, including nerve and muscle stimulation by pulsed magnetic fields, the use of magnetic forces to guide surgical instruments, and imaging utilizing the weak magnetic fields generated by brain and cardiac activity, are currently under investigation.

  4. Selective Leaching Process for Neodymium Recovery from Scrap Nd-Fe-B Magnet

    NASA Astrophysics Data System (ADS)

    Lee, Ching-Hwa; Chen, Yu-Jung; Liao, Ching-Hua; Popuri, Srinivasa R.; Tsai, Shang-Lin; Hung, Chi-En

    2013-12-01

    Neodymium-iron-boron (Nd-Fe-B) magnets were most widely applied to permanent magnetic products in the world due to their high magnetic force. The increasing growth of scrap Nd-Fe-B magnets resulted in disposal problems and the reduction of neodymium (Nd) valuable resources. In this study, we developed a simple hydrometallurgical precipitation process with pH adjustment to separate and recover Nd 100 pct recovery from scrap Nd-Fe-B magnets. Several physical and chemical methods such as demagnetization, grinding, screening, and leaching processes were also adopted to investigate the recovery of Nd and other metals from scrap Nd-Fe-B magnets. The leaching process was carried out with four leaching reagents such as NaOH, HCl, HNO3, and H2SO4. Batch studies were also conducted to optimize the leaching operating conditions with respect to leaching time, concentration of leaching reagent, temperature, and solid/liquid ratio for both HCl and H2SO4 leaching reagents. Nd was successfully separated and recovered with 75.41 wt pct from optimized H2SO4 leaching solution through precipitation. Further, the purity and weight percentage of the obtained Nd product was analyzed using scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS) analysis. An X-ray diffraction (XRD) study confirmed the obtained product of Nd was in the form of NdOOH and Nd(OH)3.

  5. Interparticle interaction effects on magnetic behaviors of hematite (?-Fe2O3) nanoparticles

    NASA Astrophysics Data System (ADS)

    Can, Musa Mutlu; F?rat, Tezer; Özcan, ?adan

    2011-07-01

    The interparticle magnetic interactions of hematite (?-Fe2O3) nanoparticles were investigated by temperature and magnetic field dependent magnetization curves. The synthesis were done in two steps; milling metallic iron (Fe) powders in pure water (H2O), known as mechanical milling technique, and annealing at 600 °C. The crystal and molecular structure of prepared samples were determined by X-ray powder diffraction (XRD) spectra and Fourier transform infrared (FTIR) spectra results. The average particle sizes and the size distributions were figured out using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The magnetic behaviors of ?-Fe2O3 nanoparticles were analyzed with a vibrating sample magnetometer (VSM). As a result of the analysis, it was observed that the prepared ?-Fe2O3 nanoparticles did not perform a sharp Morin transition (the characteristic transition of ?-Fe2O3) due to lack of unique particle size distribution. However, the transition can be observed in the wide temperature range as “a continuously transition”. Additionally, the effect of interparticle interaction on magnetic behavior was determined from the magnetization versus applied field (?(M)) curves for 26±2 nm particles, dispersed in sodium oxalate matrix under ratios of 200:1, 300:1, 500:1 and 1000:1. The interparticle interaction fields, recorded at 5 K to avoid the thermal interactions, were found as ?1082 Oe for 26±2 nm particles.

  6. Temperature responsive hydrogel magnetic nanocomposites for hyperthermia and metal extraction applications

    NASA Astrophysics Data System (ADS)

    Reddy, N. Narayana; Ravindra, S.; Reddy, N. Madhava; Rajinikanth, V.; Raju, K. Mohana; Vallabhapurapu, Vijaya Srinivasu

    2015-11-01

    The present work deals with the development of temperature and magnetic responsive hydrogel networks based on poly (N-isopropylacrylamide)/acrylamido propane sulfonic acid. The hydrogel matrices are synthesized by polymerizing N-isopropylacrylamide (NIPAM) monomer in the presence of acrylamido propane sulphonicacid (AMPS) using a cross-linker (N,N-methylenebisacrylamide, MBA) and redox initiating system [ammonium persulphate (APS)/tetramethylethylenediamine (TMEDA)]. The magnetic nanoparticles are generated throughout the hydrogel networks using in situ method by incorporating iron ions and subsequent treatment with ammonia. A series of hydrogel-magnetic nanocomposites (HGMNC) are developed by varying AMPS composition. The synthesized hydrogel magnetic nanocomposites (HGMNC) are characterized by using Fourier Transform Infrared (FTIR) Spectroscopy, X-ray diffraction (XRD), Thermal Analyses and Electron Microscopy analysis (Scanning and Transmission Electron Microscope). The metal extraction capacities of the prepared hydrogel (HG) and hydrogel magnetic nanocomposites (HGMNC) were studied at different temperatures. The results suggest that HGMNCs have higher extraction capacity compared to HG and HG loaded iron ions. This data also reveals that the extraction of metals by hydrogel magnetic nanocomposites (HGMNCs) is higher at higher temperatures than room temperature. The prepared HGMNCs are also subjected to hyperthermia (cancer therapy) studies.

  7. Magnetic properties of Ni nanoparticles embedded in silica matrix (KIT-6) synthesized via novel chemical route

    NASA Astrophysics Data System (ADS)

    Dalavi, Shankar B.; Raja, M. Manivel; Panda, Rabi. N.

    2015-06-01

    Thermally stable Ni nanoparticles have been embedded in mesoporous silica matrix (KIT-6) via novel chemical reduction method by using superhydride as reducing agent. X-ray diffraction (XRD) study confirms that pure and embedded Ni nanoparticles crystallize in face centered cubic (fcc) structure. Crystallite sizes of pure Ni, 4 wt% and 8 wt% Ni in silica were estimated to be 6.0 nm, 10.4 nm and 10.5 nm, respectively. Morphology and dispersion of Ni in silica matrix were studied by scanning electron microscopy (SEM). Magnetic study shows enhancement of magnetic moments of Ni nanoparticles embedded in silica matrix compared with that of pure Ni. The result has been interpreted on the basis of size reduction and magnetic exchange effects. Saturation magnetization values for pure Ni, 4 wt% and 8 wt% Ni in silica were found to be 15.77 emu/g, 5.08 emu/g and 2.00 emu/g whereas coercivity values were 33.72 Oe, 92.47 Oe and 64.70 Oe, respectively. We anticipate that the observed magnetic properties may find application as soft magnetic materials.

  8. Synthesis, characterization and magnetic performance of Co-incorporated ordered mesoporous carbons

    SciTech Connect

    Liu, Zhi; Song, Yan; Yang, Yuan; Mi, Junhua; Deng, Liping

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer A facile one-pot aqueous self-assembly strategy for the synthesis Co-incorporated ordered mesoporous carbons (Co-OMCs). Black-Right-Pointing-Pointer Co-OMCs exhibit typical ferromagnetic characteristics. Black-Right-Pointing-Pointer Saturation magnetization strength can be easily adjusted by changing the content of cobalt. Black-Right-Pointing-Pointer Carbonization temperatures have significant effects on the structure and magnetic properties of Co-OMCs. -- Abstract: Co-incorporated ordered mesoporous carbon (Co-OMC) with magnetic frameworks has been synthesized via a one-pot self-assembly strategy. The effects of cobalt loading on carbon matrix, adsorption properties and magnetic properties of the resultant mesostructured cobalt/carbon composites were investigated by nitrogen sorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TG) and magnetometer measurements. The results show that the mesoporous composites with a high cobalt content (such as 18.0 wt%) possess an ordered and uniform mesoporous structure (5.3 nm), high surface areas (up to 687 m{sup 2}/g) and high pore volumes (up to 0.54 cm{sup 3}/g). Cobalt nanoparticles of size 4-9 nm are confined inside the mesopores or walls of the mesoporous carbon. These materials exhibit typical ferromagnetic characteristics. The saturation magnetization strength can be easily adjusted by changing the content of cobalt. The carbonization temperatures have significant effects on the structure and magnetic properties of Co-OMC also.

  9. New method for gas and oil shale reservoirs characterisation using magnetic analysis

    NASA Astrophysics Data System (ADS)

    Ivakhnenko, Aleksandr; Telman, Meruert; Makarova, Maria; Zhaksylyk, Zhanaim; Abirov, Rustem; Makhatova, Meruyert

    2015-04-01

    This research describes proposed method for determination of total organic content (TOC), clay typing and relative degree of maturation in shale unconventional reservoirs based on analysis of magnetic properties of shales. Experimental measurements were undertaken in shales from United Kingdom (Edinburgh shales) and Kazakhstan for comparison of their magnetic properties, including low field and high field magnetic susceptibilities, together with SEM and XRD analysis. The results showed that studied shales comprised of various clay types had different capacity in accumulation of organic matter, thus, affecting the total organic content and magnetic properties. Based on the results we proposed magnetic indicators (MI) of productive gas and oil shale intervals in order to determine relative TOC, clay typing and a degree of maturation. The set of magnetic measurements, used as a logging tool or core scanning procedure, can potentially provide data about selecting the best shale productive reservoir horizons. This can be a non-destructive and rapid method for shale reservoir characterization, being used routinely in both laboratory and field conditions.

  10. Structural and Magnetic Properties of Zinc and Silicon Oxides Doped Cu Ferrite for Temperature Controller Devices

    NASA Astrophysics Data System (ADS)

    Hessien, M. M.; Ahmed, E. M.; Hemeda, O. M.

    2015-10-01

    The effects of Si+4 and Zn+2 substitutions on the structural and magnetic properties of Cu1-xZnx+ySiyFe2-2yO4 ferrites prepared by double sintering ceramic technique have been investigated. From X-ray diffraction analysis, it was found that substitution of Zn and Si enhanced sintering process and crystallization. The XRD peaks increase by increasing Zn and Si content. On the other hand, the initial permeability decreases sharply at Curie temperature for all samples, which makes Zn/Si co-doped CuFe2O4 spinel ferrites a very promising candidate for magnetic switches, magnetic temperature transducers (MTT), and for fabrication of temperature sensitive controller devices. The important change of Curie temperature of CuFe2O4 compound occurs by simply controlling the content of Zn and Si within CuFe2O4 and results in obtaining magnetic materials with desired Curie temperature. Magnetic hysteresis loop measurements show that the samples have soft magnetic character.

  11. Influences of P doping on magnetic phase transition and structure in MnCoSi ribbon

    NASA Astrophysics Data System (ADS)

    Du, Qian-Heng; Chen, Guo-Fu; Yang, Wen-Yun; Hua, Mu-Xin; Du, Hong-Lin; Wang, Chang-Sheng; Liu, Shun-Quan; Hang, Jing-Zhi; Zhou, Dong; Zhang, Yan; Yan, Jin-Bo

    2015-06-01

    The structure and magnetic properties of MnCoSi1- x Px (x = 0.05-0.50) are systematically investigated. With P content increasing, the lattice parameter a increases monotonically while both b and c decrease. At the same time, the temperature of metamagnetic transition from a low-temperature non-collinear ferromagnetic state to a high-temperature ferromagnetic state decreases and a new magnetic transition from a higher-magnetization ferromagnetic state to a lower-magnetization ferromagnetic state is observed in each of these compounds for the first time. This is explained by the changes of crystal structure and distance between Mn and Si atoms with the increase of temperature according to the high-temperature XRD result. The metamagnetic transition is found to be a second-order magnetic transition accompanied by a low inversed magnetocaloric effect (1.0 J·kg-1·K-1 at 5 T) with a large temperature span (190 K at 5 T) compared with the scenario of MnCoSi. The changes in the order of metamagnetic transition and structure make P-doped MoCoSi compounds good candidates for the study of magnetoelastic coupling and the modulation of magnetic phase transition. Project supported by the National Natural Science Foundation of China (Grant No. 11275013), the Fund from the National Physics Laboratory, China Academy of Engineering Physics (Grant No. 2013DB01), and the National Key Basic Research Program of China (Grant No. 2010CB833104).

  12. Iron oxide nanocomposite magnets produced by partial reduction of strontium hexaferrite

    NASA Astrophysics Data System (ADS)

    Tikkanen, Jussi; Paturi, Petriina

    2014-07-01

    Isotropic bulk nanocomposite permanent magnets were produced with strontium hexaferrite, SrO·6Fe2O3, and magnetite, Fe3O4, as the magnetically hard and soft components. A novels synthesis scheme based on the partial reduction of SrO·6Fe2O3 was employed. In two parallel experiments, nano- and microcrystalline SrO·6Fe2O3 particles were compacted into pellets along with a controlled, understoichiometric amount of potato starch as a reducing agent. The pellets were then sintered in a passive atmosphere. Based on XRD and room temperature magnetic hysteresis measurements, it was concluded that a fraction of the SrO·6Fe2O3 input material had been reduced into Fe3O4. In comparison with pure SrO·6Fe2O3 control pellets, these composites exhibited maximum energy product increases in excess of 5 % due to remanence boosting. The improvement of magnetic properties was attributed to an efficient exchange spring coupling between the magnetic phases. Interestingly, as the synthesis scheme also worked for microcrystalline SrO·6Fe2O3 , the method could presumably be adapted to yield crystallographically oriented bulk nanocomposite magnets.

  13. Realization of highest specific absorption rate near superparamagnetic limit of CoFe2O4 colloids for magnetic hyperthermia applications

    NASA Astrophysics Data System (ADS)

    Krishna Surendra, Muvvala; Dutta, Rajesh; Ramachandra Rao, M. S.

    2014-04-01

    Magnetic nanoparticles offer some attractive possibilities in biomedicine with local heat generation abilities. Here we report on the realization of highest specific absorption rate (˜2 kW g-1) and a stable dynamic heat production (42-46 °C) using oleic acid coated CoFe2O4 based ferrofluids which are very promising for hyperthermia applications. CoFe2O4 nanoparticles with different sizes were prepared via co-precipitation method followed by heat treatment in the temperature range 100-600 °C to vary the particle sizes from 12-24 nm. Structural analysis using high resolution transmission electron microscopy (HRTEM) shows well separated oleic acid coated CoFe2O4 nanoparticles with a tapered spherical nature and narrow size (3 nm) distribution. Thermo-gravimetric analysis reveals the strong bonding of oleic acid to the CoFe2O4 nanoparticles. Magnetization studies show oleic acid coated CoFe2O4 nanoparticles have high saturation magnetization and reduced surface spin randomization compared to bare particles. Heat production efficiency was studied near the superparamagnetic limit of CoFe2O4 as a function of magnetic core size and ferrofluid concentration. For a given particle size and concentration, the maximum specific absorption rate varies as the square of the magnetic field applied. Notable increase in the maximum specific absorption rate was found with decrease in particle size and concentration. MTT assay studies with L-929 cells using oleic acid coated CoFe2O4 nanoparticles reveals that the particles with a size of 12 nm are more biocompatible compared to particles with a size of 24 nm.

  14. Anti-cancer drug loaded iron-gold core-shell nanoparticles (Fe@Au) for magnetic drug targeting.

    PubMed

    Kayal, Sibnath; Ramanujan, Raju Vijayaraghavan

    2010-09-01

    Magnetic drug targeting, using core-shell magnetic carrier particles loaded with anti-cancer drugs, is an emerging and significant method of cancer treatment. Gold shell-iron core nanoparticles (Fe@Au) were synthesized by the reverse micelle method with aqueous reactants, surfactant, co-surfactant and oil phase. XRD, XPS, TEM and magnetic property measurements were utilized to characterize these core-shell nanoparticles. Magnetic measurements showed that the particles were superparamagnetic at room temperature and that the saturation magnetization decreased with increasing gold concentration. The anti-cancer drug doxorubicin (DOX) was loaded onto these Fe@Au nanoparticle carriers and the drug release profiles showed that upto 25% of adsorbed drug was released in 80 h. It was found that the amine (-NH2) group of DOX binds to the gold shell. An in vitro apparatus simulating the human circulatory system was used to determine the retention of these nanoparticle carriers when exposed to an external magnetic field. A high percentage of magnetic carriers could be retained for physiologically relevant flow speeds of fluid. The present findings show that DOX loaded gold coated iron nanoparticles are promising for magnetically targeted drug delivery. PMID:21133071

  15. Magnetic solid-phase extraction based on mesoporous silica-coated magnetic nanoparticles for analysis of oral antidiabetic drugs in human plasma.

    PubMed

    de Souza, Karynne Cristina; Andrade, Gracielle Ferreira; Vasconcelos, Ingrid; de Oliveira Viana, Iara Maíra; Fernandes, Christian; de Sousa, Edésia Martins Barros

    2014-07-01

    In the present work, magnetic nanoparticles embedded into mesoporous silica were prepared in two steps: first, magnetite was synthesized by oxidation-precipitation method, and next, the magnetic nanoparticles were coated with mesoporous silica by using nonionic block copolymer surfactants as structure-directing agents. The mesoporous SiO2-coated Fe3O4 samples were functionalized using octadecyltrimethoxysilane as silanizing agent. The pure and functionalized silica nanoparticles were physicochemically and morphologically characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2 adsorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The resultant magnetic silica nanoparticles were applied as sorbents for magnetic solid-phase extraction (MSPE) of oral antidiabetic drugs in human plasma. Our results revealed that the magnetite nanoparticles were completely coated by well-ordered mesoporous silica with free pores and stable pore walls, and that the structural and magnetic properties of the Fe3O4 nanoparticles were preserved in the applied synthesis route. Indeed, the sorbent material was capable of extracting the antidiabetic drugs from human plasma, being useful for the sample preparation in biological matrices. PMID:24857494

  16. Superconducting magnets for whole body magnetic resonance imaging

    SciTech Connect

    Murphy, M.F.

    1989-03-01

    Superconducting magnets have achieved preeminence in the magnetic resonance imaging (MRI) industry. Further growth in this market will depend on reducing system costs, extending medical applications, and easing the present siting problem. New magnet designs from Oxford address these issues. Compact magnets are economical to build and operate. Two 4 Tesla whole body magnets for research in magnetic resonance spectroscopy (MRS) are now in operation. Active-Shield magnets, by drastically reducing the magnetic fringe fields, will allow MRI systems with superconducting magnets to be located in previously inaccessible sites.

  17. Remanent magnetism at Mars

    NASA Technical Reports Server (NTRS)

    Curtis, S. A.; Ness, N. F.

    1988-01-01

    It is shown that a strong case can be made for an intrinsic magnetic field of dynamo origin for Mars earlier in its history. The typical equatorial magnetic field intensity would have been equal to about 0.01-0.1 gauss. The earlier dynamo activity is no longer extant, but a significant remanent magnetic field may exist. A highly non-dipole magnetic field could result from the remanent magnetization of the surface. Remanent magnetization may thus play an important role in the Mars solar wind interactions, in contrast to Venus with its surface temperatures above the Curie point. The anomalous characteristics of Mars'solar wind interaction compared to that of Venus may be explicable on this basis.

  18. Magnetic heat pumping

    NASA Technical Reports Server (NTRS)

    Brown, G. V. (inventor)

    1983-01-01

    The method employs ferromagnetic or ferromagnetic elements, preferably of rare-earth based material, for example gadolinium, and preferably employs a regenerator. The steps comprise controlling the temperature and applied magnetic field of the element to cause the state of the element as represented on a temperature-magnetic entropy diagram repeatedly to traverse a loop. The loop may have a first portion of concurrent substantially isothermal or constant temperature and increasing applied magnetic field, a second portion of lowering temperature and constant applied magnetic field, a third portion of isothermal and decreasing applied magnetic field, and a fourth portion of increasing temperature and constant applied magnetic field. Other loops may be four sided, with, for example, two isotherms and two adiabats (constant entropy portions.

  19. Passive magnetic bearing system

    DOEpatents

    Post, Richard F.

    2014-09-02

    An axial stabilizer for the rotor of a magnetic bearing provides external control of stiffness through switching in external inductances. External control also allows the stabilizer to become a part of a passive/active magnetic bearing system that requires no external source of power and no position sensor. Stabilizers for displacements transverse to the axis of rotation are provided that require only a single cylindrical Halbach array in its operation, and thus are especially suited for use in high rotation speed applications, such as flywheel energy storage systems. The elimination of the need of an inner cylindrical array solves the difficult mechanical problem of supplying support against centrifugal forces for the magnets of that array. Compensation is provided for the temperature variation of the strength of the magnetic fields of the permanent magnets in the levitating magnet arrays.

  20. Common Magnets, Unexpected Polarities

    NASA Astrophysics Data System (ADS)

    Olson, Mark

    2013-11-01

    In this paper, I discuss a "misconception" in magnetism so simple and pervasive as to be typically unnoticed. That magnets have poles might be considered one of the more straightforward notions in introductory physics. However, the magnets common to students' experiences are likely different from those presented in educational contexts. This leads students, in my experience, to frequently and erroneously attribute magnetic poles based on geometric associations rather than actual observed behavior. This polarity discrepancy can provide teachers the opportunity to engage students in authentic inquiry about objects in their daily experiences. I've found that investigation of the magnetic polarities of common magnets provides a productive context for students in which to develop valuable and authentic scientific inquiry practices.