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1

HRTEM, SEM and XRD characterization of nanocrystalline Sb 2S 3 thin films deposited by chemical bath route  

Microsoft Academic Search

In the present research paper, Sb2S3 thin films were deposited onto glass substrates at 279 K for various deposition periods. Preparative parameters such as bath composition, complexing agent, deposition time are optimized to get to hole free and chemically uniform Sb2S3 nanocrystalline thin films. Characterization of such deposited films was carried out by use of X-ray diffraction (XRD), high-resolution electron

R. S Mane; C. D Lokhande

2003-01-01

2

A combined study by XRD, FTIR, TG and HRTEM on the structure of delaminated Fe-intercalated/pillared clay.  

PubMed

Fe-PILC samples were synthesized by the reaction between Na(+)- and/or Ca(2+)-montmorillonite (Mt) and base-hydrolyzed solutions of Fe(III) nitrate. Different from the known usual microporous pillared structure, a meso-microporous delaminated structure containing intercalated or pillared fragments was found in the respective resulting Fe-intercalated or -pillared clays. XRD patterns of Na(+)-Mt-based Fe-intercalated/pillared clays show one large d-spacing above 6.4 nm corresponding to the mesoporous delaminated part, whereas another d-spacing of ca. 1.5 nm was indicative of the microporous pillared part. Fe-intercalated/pillared clays based on Ca(2+)-Mt lead to similar results, but with a d-spacing less than 6 nm and a second low intense d-spacing less than 1.5 nm. In the delaminated Fe-intercalated clays, NO(-)(3) anions were retained even after thorough washing process. They play as counterions to neutralize the positive-charged iron aggregates in the delaminated structure, and can be exchanged by heteropolyanions as [PW(12)O(40)](3-). The delaminated Fe-pillared clays show good thermal stability at 500 degrees C and exhibit at this temperature dramatically higher specific surface area and porosity than the starting montmorillonites. However, calcination at a higher temperature leads to the formation of nanocrystalline hematite. Air-drying after ethanol extraction (EAD) method has an advantage over air-drying (AD) method in preserving the delaminated structure. PMID:18502444

Yuan, Peng; Annabi-Bergaya, Faïza; Tao, Qi; Fan, Mingde; Liu, Zongwen; Zhu, Jianxi; He, Hongping; Chen, Tianhu

2008-08-01

3

Evolution of clay mineral assemblages in the Tinguiririca geothermal field, Andean Cordillera of central Chile: an XRD and HRTEM-AEM study  

NASA Astrophysics Data System (ADS)

HRTEM textural evidence shows that clay minerals in the Tinguiririca geothermal field (Andean Cordillera, central Chile) are the result of direct alteration of former volcanic glass and minerals by hydrothermal fluids at similar temperatures to the present day. They show the classical pattern of diagenetic transformation from smectite at the top to illite at the bottom, with the progressive formation of corrensite and chlorite. The high fluid/rock ratio, disposability of necessary cations and absence of previous detrital phyllosilicates allow the consideration of this area as a natural laboratory to establish the extreme ideal conditions for very low-T reactions. Transformations from smectite to R1 illite-smectite (I-S) and from these to R3 mixed-layers occur respectively at 80-120 °C and 125-180 °C. In spite of ideal genetic conditions, the new-formed minerals show all the defective character and lack of textural and chemical equilibrium previously described in the literature for diagenetic and hydrothermal low-temperature assemblages. Chemistry of smectite-illite phases evolves basically through a diminution of the pyrophyllitic component toward a theoretical muscovite (Si4 + + ? -> Al3 ++ K+). However, a second chemical vector (Si4 ++ Mg2 + ? Al3 ++ Al3 +), that is, decreasing of the tschermack component, also contributes to the evolution toward the less Si-more Al rich muscovite in relation to the original smectite. Residual Mg (and Fe) from the latter reaction is consumed in the genesis of chloritic phases. Nevertheless, as a consequence of the lack of chemical equilibrium (probably because of the short time-scale of the geothermal alteration processes), the composition of clay minerals is highly heterogeneous at the level of a single sample. Consequently, the respective fields of smectite, R1 I-S and R3 I-S overlap each other, making the distinction among these three phases impossible based exclusively on chemical data.

Vázquez, M.; Nieto, F.; Morata, D.; Droguett, B.; Carrillo-Rosua, F. J.; Morales, S.

2014-08-01

4

Size distribution of magnetic iron oxide nanoparticles using Warren-Averbach XRD analysis  

NASA Astrophysics Data System (ADS)

We use the Fourier transform based Warren-Averbach (WA) analysis to separate the contributions of X-ray diffraction (XRD) profile broadening due to crystallite size and microstrain for magnetic iron oxide nanoparticles. The profile shape of the column length distribution, obtained from WA analysis, is used to analyze the shape of the magnetic iron oxide nanoparticles. From the column length distribution, the crystallite size and its distribution are estimated for these nanoparticles which are compared with size distribution obtained from dynamic light scattering measurements. The crystallite size and size distribution of crystallites obtained from WA analysis are explained based on the experimental parameters employed in preparation of these magnetic iron oxide nanoparticles. The variation of volume weighted diameter (Dv, from WA analysis) with saturation magnetization (Ms) fits well to a core shell model wherein it is known that Ms=Mbulk(1-6g/Dv) with Mbulk as bulk magnetization of iron oxide and g as magnetic shell disorder thickness.

Mahadevan, S.; Behera, S. P.; Gnanaprakash, G.; Jayakumar, T.; Philip, J.; Rao, B. P. C.

2012-07-01

5

XRD, Mössbauer and magnetic properties of MgxCo1-xFe2O4 nanoferrites  

NASA Astrophysics Data System (ADS)

We report Mössbauer spectroscopy and magnetization studies of MgxCo1-xFe2O4 (0?x?1.0) nanoferrites. The crystallite size varies between 9 nm and 15 nm. The properties were investigated by X-ray diffraction (XRD), 57Fe Mössbauer spectroscopy and magnetometry. The XRD results indicate pure cubic spinel structure for all the compounds. The evolution of the properties has been explained on the basis of Mg content and crystallite sizes. The Mössbauer and magnetization results show strong dependence of the properties on crystallite size and non-magnetic Mg2+ ion concentration.

Dlamini, W. B.; Msomi, J. Z.; Moyo, T.

2015-01-01

6

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

E-print Network

­optic Kerr effect (MOKE). The NSOM-MOKE image clearly shows the magnetization of the nano- magnets, while microscopy, magnetooptic Kerr effect, magnetotactic bacteria, magnetospirillum gryphiswaldense, nanomagnets under harsh conditions (e.g., high temperature and pressure) and results in nanoparticles that can

Mittal, Aditya

7

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

NASA Technical Reports Server (NTRS)

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).

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

1994-01-01

8

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

NASA Astrophysics Data System (ADS)

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.

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

9

Synthesis of BaFe12O19\\/MCM-41 Magnetic NanoComposite  

Microsoft Academic Search

Magnetic nano-composite was synthesized by modified incorporation of iron-barium complex into ordered meso-porous silica (MCM-41) as a matrix. Phase composition, morphology and magnetic properties of the synthesized MCM-41 and the resulted composite were characterized by XRD, HRTEM\\/EDS and VSM techniques, respectively. Low angle XRD patterns of both calcined MCM-41 and resulted composite exhibit the characteristic reflection of high quality hexagonal

A. Ataie; H. R. Emamian; A. Honarbakhsh-Raouf

2009-01-01

10

Nanoscale chemical and structural study of Co- based FEBID structures by STEM-EELS and HRTEM  

E-print Network

NANO EXPRESS Open Access Nanoscale chemical and structural study of Co- based FEBID structures by STEM-EELS and HRTEM Rosa Córdoba1,2, Rodrigo Fernández-Pacheco1,3, Amalio Fernández-Pacheco1,2, Alexandre Gloter3, César Magén1,2,4, Odile Stéphan3... electron microscopy at the nanometric scale. The obtained results allow us to correlate the chemical and structural properties with the functionality of these magnetic nanostructures. Keywords: Co deposits, FEBID, EELS, HRTEM Background Despite its great...

Cordoba, Rosa; Fernandez-Pacheco, Rodrigo; Fernandez-Pacheco, Amalio; Gloter, Alexandre; Magen, Cesar; Stephan, Odile; Ricardo Ibarra, Manuel; De Teresa, Jose Maria

2011-11-15

11

Chain-like and dinuclear coordination polymers in lanthanide (Nd, Eu) oxochloride complexes with 2,2':6',2''-terpyridine: synthesis, XRD structure and magnetic properties.  

PubMed

The solvothermal reactions (at 180 °C for 48 h) of a mixture of lanthanide chlorides (Nd, Eu) with the tridendate heterocyclic nitrogen ligand, 2,2':6',2''-terpyridine (terpy), in ethanol medium give rise to the formation of crystalline mixed chloro-hydroxo-aquo complex Ln(2)Cl(5)(OH)(H(2)O)(terpy). Its crystal structure consists of the connection of eight- and nine-fold coordinated lanthanide centers linked to each other via ?(2,3)-chloro and ?(3)-hydroxo species to form a tetranuclear unit, which are then further connected through chloro edges to generate infinite ribbons. Only one lanthanide cation in every two is chelated by terpy. Similar molar composition of the starting reactants led to the crystallization at room temperature of a second type of complex LnCl(3)(H(2)O)(terpy) (Ln = Nd, Eu). It is built up from the molecular assembly of dinuclear species containing two eight-fold coordinated lanthanide centers chelated by terpy and linked through a ?(2)-Cl edge. Luminescence spectra have been collected for the europium-based compound and indicates a strong red signal with the expected bands from the F-D transitions. The magnetic properties of the four compounds were investigated. Their behaviors correspond to that of the rare-earth ions present in the structure. The magnetic susceptibility of the neodymium-based compounds agrees with that of the Nd(III) ion with an (4)I(9/2) ground state split by crystal field. Concerning the Eu(III) derivatives, the term (7)F is split by spin-orbit coupling, the first excited states being thermally populated. Accordingly, the thermal dependence of the magnetic susceptibility was nicely reproduced by using appropriate analytical relations. The refined values of the spin-orbit coupling are consistent with the energies of the electronic levels deduced from the photoluminescence spectra. Unexpectedly, the magnetic susceptibility exhibits a hysteretic behavior in the range 45-75 K. PMID:21818485

Lhoste, Jérôme; Pérez-Campos, Ana; Henry, Natacha; Loiseau, Thierry; Rabu, Pierre; Abraham, Francis

2011-09-28

12

In situ XRD, XAS, and magnetic susceptibility study of the reduction of ammonium nickel phosphate NiNH4PO4 x H2O into nickel phosphide.  

PubMed

The reduction of the ammonium nickel phosphate NiNH(4)PO(4) x H(2)O precursor into nickel phosphide (Ni(2)P), a highly active phase in hydrotreating catalysis, was studied using a combination of magnetic susceptibility and in situ X-ray diffraction and X-ray absorption spectroscopy (XAS) techniques. The transformation of NiNH(4)PO(4) x H(2)O into Ni(2)P could be divided into three distinguishable zones: (1) from room temperature to 250 degrees C, the NiNH(4)PO(4) x H(2)O structure was essentially retained; (2) from 300 to 500 degrees C, only an amorphous phase was observed; (3) above 500 degrees C, a crystallization process occurred with the formation of Ni(2)P. An in situ XAS study and magnetic susceptibility measurements clearly revealed for the first time that the amorphous region corresponds to the nickel pyrophosphate phase alpha-Ni(2)P(2)O(7). The phosphate reduction into phosphide did not start before 550 degrees C and led to the selective formation of Ni(2)P at 650 degrees C. PMID:19236008

Berhault, Gilles; Afanasiev, Pavel; Loboué, Hermione; Geantet, Christophe; Cseri, Tivadar; Pichon, Christophe; Guillot-Deudon, Catherine; Lafond, Alain

2009-04-01

13

Mineralogical Characterization of Vigarano Matrix: HRTEM and EFTEM Observations  

NASA Technical Reports Server (NTRS)

HRTEM and EFTEM have been used to study Vigarano matrix. Fine-grained rim olivines commonly contain inclusions of amorphous carbon and a Ca-Al-rich phase, whereas olivines in the clastic matrix contain rare inclusions of poorly graphitized carbon. Additional information is contained in the original extended abstract.

Abreu, N. M.; Brearley, A. J.

2002-01-01

14

MEGACELL: a nanocrystal model construction software for HRTEM multislice simulation.  

PubMed

Image simulation has an invaluable importance for the accurate analysis of High Resolution Transmission Electron Microscope (HRTEM) results, especially due to its non-linear image formation mechanism. Because the as-obtained images cannot be interpreted in a straightforward fashion, the retrieval of both qualitative and quantitative information from HRTEM micrographs requires an iterative process including the simulation of a nanocrystal model and its comparison with experimental images. However most of the available image simulation software requires atom-by-atom coordinates as input for the calculations, which can be prohibitive for large finite crystals and/or low-symmetry systems and zone axis orientations. This paper presents an open source citation-ware tool named MEGACELL, which was developed to assist on the construction of nanocrystals models. It allows the user to build nanocrystals with virtually any convex polyhedral geometry and to retrieve its atomic positions either as a plain text file or as an output compatible with EMS (Electron Microscopy Software) input protocol. In addition to the description of this tool features, some construction examples and its application for scientific studies are presented. These studies show MEGACELL as a handy tool, which allows an easier construction of complex nanocrystal models and improves the quantitative information extraction from HRTEM images. PMID:21740871

Stroppa, Daniel G; Righetto, Ricardo D; Montoro, Luciano A; Ramirez, Antonio J

2011-07-01

15

On the acidity of saponite materials: a combined HRTEM, FTIR, and solid-state NMR study.  

PubMed

Acid clays were prepared by exchanging a synthetic saponite in HCl solutions of different concentration (0.01 and 1M, respectively). A combined experimental approach (XRD, HRTEM, N2 physisorption, solid-state MAS NMR, and TGA) was used to investigate on the structural, morphological, and textural features of the samples treated under mild and strong acid conditions. FTIR spectroscopy of adsorbed probe molecules with different basicity (e.g., CO and NH3) was used to monitor the surface acid properties and acid site distribution. XRD and SS-MAS NMR indicated that the activation under mild acid conditions does not alter the clay structure, while a deep modification of the saponite framework occurred after ion exchange in 1 M HCl solution. The presence of porous amorphous silica phase after treatment under strong acid conditions was confirmed by TEM inspection augmented by SS-MAS NMR and FTIR spectroscopy. N2 and Ar physisorption measurements suggested that cavitation phenomena occurred in saponite structure. N2 physisorption confirmed that the porosity and surface area of the samples are strongly modified upon strong acid treatment. FTIR spectroscopy of adsorbed NH3 pointed out that the H-exchange in mild conditions increased the number of surface Brønsted acid sites. Conversely, these sites are significantly depleted after treatment under strong acid conditions. The use of CO as a FTIR probe molecule, which is applied for the first time to study synthetic acid clays, allowed to monitor distribution and strength of Brønsted acid sites, whose acidity is similar to that of strong acid zeolites. The Al-OH sites with medium acidity are also found in acid-activated saponites. The distribution of strong and medium acid sites is strictly dependent on the acid conditions adopted. PMID:18251562

Bisio, C; Gatti, G; Boccaleri, E; Marchese, L; Bertinetti, L; Coluccia, S

2008-03-18

16

Interfacial magnetic coupling between Fe nanoparticles in Fe–Ag granular alloys.  

PubMed

The role of the interface in mediating interparticle magnetic interactions has been analysed in Fe50Ag50 and Fe55Ag45 granular thin films deposited by the pulsed laser deposition technique (PLD). These samples are composed of crystalline bcc Fe (2–4 nm) nanoparticles and fcc Ag (10–12 nm) nanoparticles, separated by an amorphous Fe50Ag50 interface, occupying around 20% of the sample volume, as determined by x-ray diffraction (XRD), x-ray absorption spectroscopy (XAS), and high resolution transmission electron microscopy (HRTEM). Interfacial magnetic coupling between Fe nanoparticles is studied by dc magnetization and x-ray magnetic circular dichroism (XMCD) measurements at the Fe K and Ag L2,3 edges. This paper reveals that these thin films present two magnetic transitions, at low and high temperatures, which are strongly related to the magnetic state of the amorphous interface, which acts as a barrier for interparticle magnetic coupling. PMID:22166763

Alonso, J; Fdez-Gubieda, M L; Sarmiento, G; Chaboy, J; Boada, R; García Prieto, A; Haskel, D; Laguna-Marco, M A; Lang, J C; Meneghini, C; Fernández Barquín, L; Neisius, T; Orue, I

2012-01-20

17

Microstructures and interfaces in NiAl martensite: comparing HRTEM observations with continuum theories  

E-print Network

Microstructures and interfaces in Ni­Al martensite: comparing HRTEM observations with continuum October 2001 Abstract Different microstructural configurations of Ni­Al martensite are described. Keywords: Martensite; Ni­Al; HRTEM; Continuum theory; Microstructure 1. Introduction Intermetallic Ni­Al

Ball, John M.

18

Synthesis of BaFe12O19/MCM-41 Magnetic Nano-Composite  

NASA Astrophysics Data System (ADS)

Magnetic nano-composite was synthesized by modified incorporation of iron-barium complex into ordered meso-porous silica (MCM-41) as a matrix. Phase composition, morphology and magnetic properties of the synthesized MCM-41 and the resulted composite were characterized by XRD, HRTEM/EDS and VSM techniques, respectively. Low angle XRD patterns of both calcined MCM-41 and resulted composite exhibit the characteristic reflection of high quality hexagonal meso-structures. TEM image of the composite material reveals that the hexagonal ordered meso-structure MCM-41 with a mean pore size of 3 nm was not affected by wet impregnation and re-calcination in order to incorporate with barium hexaferrite. The EDX analysis indicates presence of barium-iron composition inside the MCM-41 channels. The resulted composite material showed a superparamagnetic nature.

Ataie, A.; Emamian, H. R.; Honarbakhsh-raouf, A.

2009-06-01

19

Ceramic/metal nanocomposites by lyophilization: Processing and HRTEM study  

SciTech Connect

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.

Gutierrez-Gonzalez, C.F. [Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN), Consejo Superior de Investigaciones Cientificas - CSIC - Universidad de Oviedo - UO - Principado de Asturias - PA, Parque Tecnologico de Asturias, 33428 Llanera (Spain)] [Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN), Consejo Superior de Investigaciones Cientificas - CSIC - Universidad de Oviedo - UO - Principado de Asturias - PA, Parque Tecnologico de Asturias, 33428 Llanera (Spain); Agouram, S. [Department of Applied Physics and Electromagnetism, Universitat de Valencia, 46100 Burjassot (Spain)] [Department of Applied Physics and Electromagnetism, Universitat de Valencia, 46100 Burjassot (Spain); Torrecillas, R. [Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN), Consejo Superior de Investigaciones Cientificas - CSIC - Universidad de Oviedo -UO - Principado de Asturias- PA, Parque Tecnologico de Asturias, 33428 Llanera (Spain)] [Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN), Consejo Superior de Investigaciones Cientificas - CSIC - Universidad de Oviedo -UO - Principado de Asturias- PA, Parque Tecnologico de Asturias, 33428 Llanera (Spain); Moya, J.S. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas (ICMM-CSIC), Cantoblanco, 28049 Madrid (Spain)] [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas (ICMM-CSIC), Cantoblanco, 28049 Madrid (Spain); Lopez-Esteban, S., E-mail: s.lopez@cinn.es [Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN), Consejo Superior de Investigaciones Cientificas - CSIC - Universidad de Oviedo - UO - Principado de Asturias - PA, Parque Tecnologico de Asturias, 33428 Llanera (Spain)

2012-02-15

20

Magnetic photocatalysts with a p-n junction: Fe3O4 nanoparticle and FeWO4 nanowire heterostructures.  

PubMed

Magnetic n-type semiconductor Fe3O4 nanoparticle and p-type semiconductor FeWO4 nanowire heterostructures were successfully synthesized without any surfactants or templates via a facile one-step hydrothermal process at 160 °C. The heterojunction structure and morphology were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). Magnetic measurements indicated the coexistence of ferrimagnetic behavior of Fe3O4 and weak antiferromagnetic behavior of FeWO4. The degradation of methylene blue (MB) under UV-Visible light irradiation was studied as a model experiment to evaluate the catalytic activity of the Fe3O4/FeWO4 heterostructure p-n junctions. The decomposition efficiency was 97.1% after one hour UV-Visible irradiation. This magnetic photocatalyst can be easily recovered from the solution using a permanent magnet and redispersed by removing the magnet. PMID:25201551

Cao, Xuan; Chen, Yan; Jiao, Shihui; Fang, Zhenxing; Xu, Man; Liu, Xu; Li, Lu; Pang, Guangsheng; Feng, Shouhua

2014-11-01

21

Characterization of illuminated manuscripts by laboratory-made portable XRD and micro-XRD systems.  

PubMed

Illuminated Arabic manuscripts have been studied, employing two laboratory-made X-ray diffraction (XRD) systems developed recently in the C2RMF laboratory. The validity of the micro-XRD and XRD portable systems for the study of this type of artworks has been demonstrated. A common observation in all the analyses is the presence of calcite and rutile; also, hematite, goethite, cinnabar, brass, anatase and barite were detected in the various colours. Differences between the results obtained by both techniques due to acquisition mode are discussed. In addition, other techniques such as X-ray fluorescence (XRF) and micro-Raman were used for the complete characterization of the manuscripts. PMID:19685044

Duran, A; Perez-Rodriguez, J L; Espejo, T; Franquelo, M L; Castaing, J; Walter, P

2009-12-01

22

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

PubMed

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

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

2015-01-01

23

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

E-print Network

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

Dunin-Borkowski, Rafal E.

24

HRTEM study of zircon from Eliseev anorthosite complex, Antarctica  

SciTech Connect

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).

Wirth, R.; Kaempf, H. [GeoForschungsZentrum Potsdam (Germany); Hoehndorf, A. [Bundesanstalt fuer Geowissenschaften und Rohstoffe, Hannover (Germany)

1996-12-31

25

Swelling of ion-irradiated 3C-SiC characterized by synchrotron radiation based XRD and TEM  

NASA Astrophysics Data System (ADS)

An experimental technique was established to characterize irradiation-induced volume swelling through a combined utilization of synchrotron radiation-based X-ray diffraction (XRD) and transmission electron microscopy (TEM). 3C-SiC specimens were irradiated by Si2+ ions (5 MeV) with fluences up to 5 × 1017 ion/cm2 at 1000 °C. In order to avoid the accumulation of implanted Si ions in the SiC layer, specific thicknesses of the epitaxy layer and implanted ion energy were chosen. Unresolvable black spot defects were studied by TEM, and the average size and density were calculated. XRD radial scan results of surface (0 0 2), (1 1 1), (0 2 2), (1 1 3), and (2 0 0) including peak shift and asymmetry peak broadening were observed. Different interplanar spacing information of single crystal SiC can be obtained from this XRD measurement method, making it possible to investigate the lattice expansion and volume swelling more precisely. While TEM provided a direct visualization of the microstructures and the interplanar spacing was measured from HRTEM images. It is suggested that irradiation induced point defects and compressive stress from the Si substrate were the cause of anisotropic (a = b < c) volume swelling of irradiated 3C-SiC in this study.

Lin, Yan-Ru; Ho, Chun-Yu; Chuang, Wei-Tsung; Ku, Ching-Shun; Kai, Ji-Jung

2014-12-01

26

Synthesis, Characterization and Studies on Optical, Dielectric and Magnetic Properties of undoped and Cobalt doped Nanocrystalline Bismuth Ferrite  

NASA Astrophysics Data System (ADS)

Multiferroic perovskite nanocrystalline Bismuth ferrite (BFO) and Co doped Bismuth ferrite are synthesized by chemical route annealed at 500, 550 and 600 °C. XRD studies revealed the phases formed during synthesis while crystallite size is calculated in the range of 15.4-55 nm by Scherrer's formula from the identified XRD major peaks. The FTIR spectra of undoped BFO sample synthesized at 500, 550 and 600 °C exhibits clear presence of peaks at 554 cm-1 confirms the existence of Bi-O, Fe-O stretching and bending behavior of two different M-O co-ordination using Shimadzu-8400S Spectroscopy. The microstructure, lattice image and interplanar spacing are obtained by HRTEM analysis. The particle sizes are also measured from HRTEM while the chemistry is verified by energy dispersive x-ray analysis (EDX) (Oxford Instruments, INCA). Dielectric properties are observed for both undoped and Co doped samples. The band gap energy is measured by UV-VIS characterization using Tauc equation. Magnetic measurements are carried out using Physical Properties Measurement systems.

Sarkar, K.; Mukherjee, Soumya; Mukherjee, S.; Mitra, M. K.

2014-10-01

27

Synthesis, Characterization and Studies on Optical, Dielectric and Magnetic Properties of undoped and Cobalt doped Nanocrystalline Bismuth Ferrite  

NASA Astrophysics Data System (ADS)

Multiferroic perovskite nanocrystalline Bismuth ferrite (BFO) and Co doped Bismuth ferrite are synthesized by chemical route annealed at 500, 550 and 600 °C. XRD studies revealed the phases formed during synthesis while crystallite size is calculated in the range of 15.4-55 nm by Scherrer's formula from the identified XRD major peaks. The FTIR spectra of undoped BFO sample synthesized at 500, 550 and 600 °C exhibits clear presence of peaks at 554 cm-1 confirms the existence of Bi-O, Fe-O stretching and bending behavior of two different M-O co-ordination using Shimadzu-8400S Spectroscopy. The microstructure, lattice image and interplanar spacing are obtained by HRTEM analysis. The particle sizes are also measured from HRTEM while the chemistry is verified by energy dispersive x-ray analysis (EDX) (Oxford Instruments, INCA). Dielectric properties are observed for both undoped and Co doped samples. The band gap energy is measured by UV-VIS characterization using Tauc equation. Magnetic measurements are carried out using Physical Properties Measurement systems.

Sarkar, K.; Mukherjee, Soumya; Mukherjee, S.; Mitra, M. K.

2014-09-01

28

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

SciTech Connect

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.

Srivastava, Manish [Department of Physics, Motilal Nehru National Institute of Technology, Allahabad 211004 (India); Ojha, Animesh K., E-mail: animesh_r1776@rediffmail.co [School of Engineering and Science, Jacobs University, 28759 Bremen (Germany); Chaubey, S. [Department of Physics, Motilal Nehru National Institute of Technology, Allahabad 211004 (India); Singh, Jay [Department of Chemistry, Motilal Nehru National Institute of Technology, Allahabad 211004 (India)

2010-11-15

29

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

NASA Astrophysics Data System (ADS)

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.

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

2011-01-01

30

HRTEM and EELS study of Y2O3/MgO thin films.  

PubMed

Y2O3 thin films deposited on (001)-MgO substrate have been investigated by high-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy. Digital processing of the HRTEM images reveals the presence of grains with a crystallographic structure different from that of the rest of the film (Ia3). The spectrum imaging technique has been applied in vicinity of the Y2O3/MgO interface to get a better knowledge of the phases nucleated on the substrate surface. Fine structures of the O K-edge have been studied in detail; actually two kinds of spectra have been detected in the yttrium oxide thin film. These spectra have been compared to self-consistent full multiple scattering calculations (SC-FMS). One family of spectra has then been associated to the well-known Ia3 structure. The other family of spectra has been compared to calculations performed for the other known structures (such as hexagonal or monoclinic) of Y2O3 with a little success. We have finally compared these spectra to calculations performed with a particular atomic arrangement (octahedral) of Y and O atoms, which leads to a good match between experimental and calculated spectra. Our results emphasize the benefit of coupling several techniques such as HRTEM, EELS and SC-FMS for the determination of structures at the nanometric scale. PMID:16466928

Pailloux, F; Imhoff, D; Jublot, M; Paumier, F; Gaboriaud, R J; Jaouen, M

2006-01-01

31

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

NASA Astrophysics Data System (ADS)

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.

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

2013-06-01

32

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

SciTech Connect

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.

Cady, S.L. [NASA Ames Research Center, Moffett Field, CA (United States); Wenk, H.R. [Univ. of California, Berkeley, CA (United States); Downing, K.H. [Lawrence Berkeley National Lab., CA (United States)

1996-11-01

33

HRTEM Study of yttrium oxide particles in ODS steels for fusion reactor application  

Microsoft Academic Search

An oxide dispersion strengthened ferritic-martensitic steel with yttrium oxide (Y2O3) was produced by mechanical alloying and hot isostatic pressing techniques for high-performance structures of fusion energy devices. The structure of the nanometer-sized Y2O3 particles analysed by HRTEM shows a strong correlation of its crystallographic orientation with the alloy lattice. The orientation correlations [110]YO?[111]FeCr and (11?1?)YO?(11?0)FeCr were found. The strong orientation

M. Klimiankou; R. Lindau; A. Möslang

2003-01-01

34

Room temperature optical and magnetic properties of polyvinylpyrrolidone capped ZnO nanoparticles  

SciTech Connect

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.

Chakrabarti, Mahuya, E-mail: mahuya@veccal.ernet.in [Variable Energy Cyclotron Centre, 1/AF, Bidhannagar, Kolkata-700064 (India); Das, S. [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032 (India); Chakrabarti, Keka R.; Sanyal, D.; Chakrabarti, A. [Variable Energy Cyclotron Centre, 1/AF, Bidhannagar, Kolkata-700064 (India)

2009-09-15

35

Structure, magnetic and dielectric properties of nanocrystalline Se-xFe  

NASA Astrophysics Data System (ADS)

Nanocrystalline Se-xFe (x = 3 and 5 wt%) samples were prepared by solid state reaction. XRD revealed the presence of two phases; FeSe2 and Se. HRTEM showed the epitaxial growth of FeSe2 on Se. The magnetization measurements showed ferromagnetic behavior above room temperature for sample with x = 5 wt%. The a.c. conductivity for x = 3 wt% follows the overlapping large polaron tunneling model, while for (x = 5 wt%) sample it follows the correlated barrier hoping model. The temperature dependence of the dielectric measurements revealed an anomaly above room temperature for (x = 5 wt%) sample, while it appeared at room temperature for (x = 3 wt%) sample.

EL-Sayed, Karimat; Mohamed, Mohamed Bakr; Heiba, Z. K.; Al-Nabriss, A. R.

2014-11-01

36

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

37

Structural, magnetic, and magnetoresistive properties of electrodeposited Ni5Zn21 alloy nanowires.  

PubMed

Ni5Zn21 alloy nanowires were fabricated through template-assisted electrochemical deposition method. The morphology and microstructures of as-deposited nanowires were determined by field-emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), electron diffraction (ED), and electron probe microanalysis (EPMA). The accurate composition was measured via induced coupling plasma atomic emission spectroscopy. SEM results show that Ni5Zn21 nanowires are deposited in most of the nanopores of the template, and they are continuous and dense throughout the whole length. The XRD result demonstrates that the nanowires are mainly composed of a cubic gamma phase Ni5Zn21 alloy, but there also exists a trace of Zn-rich eta phase. HRTEM and ED reveal that the alloy nanowires are polycrystalline with the crystallite size of several tens of nanometers. EPMA of a single nanowire illustrates that there exist Ni-rich microzones in as-deposited nanowires. Subsequent magnetic measurements of the array also confirmed the existence of them. In addition, it can be further inferred that the shape of Ni-rich microzones is probably barlike or disklike, from the anisotropy of zero field cooling/field cooling (ZFC/FC) curves as well as the vortex magnetization behavior of the Ni5Zn21 nanowire array. The low-temperature magnetoresistance of the Ni5Zn21 nanowire array was also measured. Giant magnetoresistance instead of anisotropic magnetoresistance is suggested to be responsible for contributing to the magnetoresistance. PMID:17034190

Liu, Lifeng; Tian, Huanfang; Xie, Sishen; Zhou, Weiya; Mu, Shicheng; Song, Li; Liu, Dongfang; Luo, Shudong; Zhang, Zengxing; Xiang, Yanjuan; Zhao, Xiaowei; Ma, Wenjun; Shen, Jun; Li, Jianqi; Wang, Chaoying; Wang, Gang

2006-10-19

38

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

PubMed

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 MoSe2 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

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

2014-10-27

39

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

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

40

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

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

41

Photoluminescence and magnetic properties of Fe-doped ZnS nano-particles synthesized by chemical co-precipitation  

NASA Astrophysics Data System (ADS)

This paper is focusing on the synthesis of Zn 1- xFe xS nano-particles with x = 0, 0.1 and 0.2 by chemical co-precipitation method, the prepared of which are characterized by XRD, EDS, TEM, PL, magnetization versus field behavior and M- T curve. In the XRD patterns, Zn 1- xFe xS nano-particles are shown of cubic zinc blende structure, and the broadening diffraction peaks consistent with the small-size characteristic of nano-materials. The diameter of nano-particles is between 3.3 and 5.5 nm according to the HR-TEM images. The EDS data confirm the existence of Fe ions in Fe-doped ZnS nanoparticles. There we found that Fe-doping did not import new energy bands or defect states, but reduced the intensity of PL peaks. The magnetization versus field behaviors were illustrated by the M- H curves at both 5 K and 300 K, respectively, where no remanence or coercive force was observed. This phenomenon indicates that the Zn 1- xFe xS ( x = 0.1) nano-particles are superparamagnetic. The zero-field-cooled (ZFC) and field-cooled (FC) magnetization curves further reveal that the blocking temperature ( TB) of the superparamagnetic behavior might be below 5 K.

Eryong, Nie; Donglai, Liu; Yunsen, Zhang; Xue, Bai; Liang, Yi; Yong, Jin; Zhifeng, Jiao; Xiaosong, Sun

2011-08-01

42

FTIR and XRD study of PMMA/PCTFE blend films  

SciTech Connect

The results are reported on solution cast PMMA-PCTFE blend films characterized using x-ray diffraction and FTIR. The nanocrystalline nature of PMMA is still seen in the blends, however, the bond modifications are clearly observed. The addition of PCTFE results in the modification in structural properties, as reflected in the XRD and FTIR spectra showing modifications in bonding as a function of PCTFE percentage.

Tripathi, S., E-mail: shilpatr3@gmail.com; Shripathi, T. [UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore-452001 (India); Tripathi, J. [Dept. of Physics, ISLE, IPS Academy, Indore-452008 (India); Agrawal, A. [Dept. of Electronics and Communications, Global Engineering College, Jabalpur-482001 (India); Sharma, A. [Department of Physics, Manipal University, Jaipur-302026 (India)

2014-04-24

43

Quantitative XRD analysis of {110} twin density in biotic aragonites.  

PubMed

{110} Twin densities in biotic aragonite have been estimated quantitatively from the peak widths of specific reflections in powder X-ray diffraction (XRD) patterns, as well as direct confirmation of the twins using transmission electron microscopy (TEM). Influence of the twin density on the peak widths in the XRD pattern was simulated using DIFFaX program, regarding (110) twin as interstratification of two types of aragonite unit layers with mirrored relationship. The simulation suggested that the twin density can be estimated from the difference of the peak widths between 111 and 021, or between 221 and 211 reflections. Biotic aragonite in the crossed-lamellar microstructure (three species) and nacreous microstructure (four species) of molluscan shells, fish otoliths (two species), and a coral were investigated. The XRD analyses indicated that aragonite crystals in the crossed-lamellar microstructure of the three species contain high density of the twins, which is consistent with the TEM examination. On the other hand, aragonite in the nacre of the four species showed almost no difference of the peak widths between the paired reflections, indicating low twin densities. The results for the fish otoliths were varied between the species. Such variation of the twin density in biotic aragonites may reflect different schemes of crystal growth in biomineralization. PMID:22989562

Suzuki, Michio; Kim, Hyejin; Mukai, Hiroki; Nagasawa, Hiromichi; Kogure, Toshihiro

2012-12-01

44

Role of inhomogeneous cation distribution in magnetic enhancement of nanosized Ni0.35Zn0.65Fe2O4: A structural, magnetic, and hyperfine study  

NASA Astrophysics Data System (ADS)

In this paper, we report the structural, microstructural, and magnetic properties of nanosized (particle size ranging from 20 to 30 nm) Ni0.35Zn0.65Fe2O4 (MA4) system synthesized via mechanochemical route followed by annealing. The Rietveld refinement is used for the first time to precisely resolve the crystal structure of a ferrite system at nanoscale. MA4 is a cubic spinel of Fd3¯m symmetry. According to XRD and HRTEM studies, it is a well crystalline sample which possesses large microstrain. In spite of its nanometric size, MA4 has displayed some notably distinct magnetic properties like, enhancement of magnetization (64 emu g-1 at 15 K), magnetic order, magnetic ordering temperature, coercivity (1000 Oe at 15 K), magnetic anisotropy energy, and reduction of superparamagnetic relaxation compared with its counterparts synthesized by chemical route. It exhibits clear hysteresis loop (HC = 50 Oe) at 300 K and ferrimagnetic ordering below the blocking temperature (˜250 K). These improvements in magnetic properties of the system are likely to be very helpful for its technological applications. Again, particles in the sample possess a ferrimagnetically aligned core (with small canting) surrounded by a magnetically disordered shell with canted spin structure. The magnetically disordered surface region of MA4 has an equilibrium cation distribution, whereas the ferrimagnetic core region possesses a nonequilibrium cation distribution. Moreover, the infield Mössbauer spectroscopic study reveals that the nearest neighbor ion configuration about [B] site Fe3+ ions is not identical. Thus, there is local chemical inhomogeneity in the sample. The cation redistribution, chemical inhomogeneity, lattice strain are identified as the causes for magnetic enhancement in MA4.

Dey, S.; Dey, S. K.; Ghosh, B.; Dasgupta, P.; Poddar, A.; Reddy, V. R.; Kumar, S.

2013-09-01

45

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

SciTech Connect

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.

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

2009-11-02

46

Anomalous magnetic behavior of La0.6Sr0.4MnO3 nano-tubes constituted with 3-12 nm particles  

NASA Astrophysics Data System (ADS)

Uniform La0.6Sr0.4MnO3 (LSMO) nanotubes of an average diameter 180 nm were synthesized by a modified sol-gel method employing nanochannel porous anodic alumina templates. The nanotubes were characterized chemically and structurally by XRD, SEM, EDX, and TEM. Postannealed (700 °C for 1 h hour) nanotubes were found to be polycrystalline from XRD and SAED studies. To get further insight into the nanotube structure, HRTEM studies were done, which revealed that obtained LSMO nanotubes were structurally constituted with nanoparticles of 3-12 nm size. These constituent nanoparticles were randomly aligned and self-knitted to build the nanotube wall. Investigation of magnetic properties at this structured nanoscale revealed remarkable irreversibility between the zero field cooling (ZFC) and field cooling (FC) magnetization curves accompanied with a peak in the ZFC curve indicating spin-glass-like behavior. Structural defects and compositional variations at surfaces and grain-boundaries of constituent nanoparticles might be responsible for this anomalous magnetic behavior.

Banerjee, Nirupam; Krupanidhi, S. B.

2013-05-01

47

The influence of spatial and temporal averaging on interpretation of HRTEM images of solid-liquid interfaces.  

PubMed

The effects of spatial and temporal averaging on high-resolution transmission electron microscope (HRTEM) images and associated intensity profiles of a solid-liquid Al interface were investigated using atomic coordinates obtained from molecular dynamics simulations. It was found that intensity profiles obtained by spatial averaging across the solid-liquid interface capture the variation in structural features nearly as well as time-averaged intensity profiles. This suggests that adequate spatial averaging of a single HRTEM image can be used to study the contrast from interfaces, and thereby, the structural details, without the need for more time-consuming, computer-intensive time averaged analyses. The limitations of this method are also discussed. PMID:23142743

Eswara Moorthy, Santhana K; Mendelev, Mikhail I; Howe, James M

2013-01-01

48

Structural and chemical characterization of Yb2O3-ZrO2 system by HAADF-STEM and HRTEM.  

PubMed

ZrO2:Yb3+ nanocrystalline phosphors with high concentrations of ytterbium ions were prepared using the sol-gel method. X-ray diffraction, high-angle annular-dark-field scanning transmission electron microscopy (HAADF-STEM), energy dispersive X-ray spectroscopy, and high-resolution transmission electron microscopy (HRTEM) were used to characterize the nanocrystalline phosphors annealed at 1000 degrees C. Unit-cell distortion and changes in the crystalline structure of the monoclinic zirconia to tetragonal zirconia, and subsequently cubic zirconia, were observed with increased Yb concentration. Yb ions were randomly distributed into the lattice of the crystalline structure. No segregation of Yb2O3 phase was observed. The substitution of Zr atoms by Yb atoms on different crystalline phases was confirmed by the experimental results and theoretical simulations of HRTEM and HAADF-STEM. PMID:19144257

Angeles-Chavez, C; Salas, P; Díaz-Torres, L A; de la Rosa, E; Esparza, R; Perez, R

2009-02-01

49

Magnetic composite BiOCl-SrFe12O19: a novel p-n type heterojunction with enhanced photocatalytic activity.  

PubMed

The magnetic composite BiOCl-SrFe12O19, a novel p-n type heterojunction was synthesized by hydrolysis with a medium temperature sintering method. The microstructure and magnetic properties of the prepared material were characterized by FTIR, XRD, SEM, TEM, HRTEM, SAED, and VSM. The results showed the [001] facet of BiOCl with high photocatalytic activity was exposed in the BiOCl-SrFe12O19. The heterostructured BiOCl-SrFe12O19 had better magnetic properties, contributing to its reuse and improvement in photocatalysis. Moreover, the composite was blessed with excellent photocatalytic activity and stability. In the BiOCl-SrFe12O19 system, SrFe12O19 not only inhibited the growth of BiOCl along the [001] direction to enhance the exposure of the [001] wafer, but also acted as a sensitizer absorbing light irradiation. The magnetic field generated from SrFe12O19 made BiOCl, under light irradiation, produce more photo-induced electrons and holes and simultaneously hampered their recombination. For the first time we propose the possible mechanism of how to enhance photocatalytic activity by a magnetic field effect originating from the magnetic photocatalyst itself. PMID:24297101

Xie, Taiping; Xu, Longjun; Liu, Chenglun; Yang, Jun; Wang, Mei

2014-02-01

50

Effect of calcination temperature on microstructure and magnetic properties of Ni0.5Zn0.25Cu0.25 Fe2O4 nanoparticles synthesized by sol-gel method  

NASA Astrophysics Data System (ADS)

This paper examines the effect of calcination process on the structural and magnetic properties material nanostructure composite of Ni0?5Zn0?25Cu0.25 Fe2O4 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.

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

2014-10-01

51

Structural, thermal and magnetic investigations of heavily Mn-doped ZnO nanoparticles  

NASA Astrophysics Data System (ADS)

We present a systemic study on the structural, thermal and magnetic properties of Zn1-xMnxO nanoparticles synthesized by a combustion method with heavily Mn doping concentrations x=0.05, 0.15 and 0.25. The structural evolutions in relation to the possible variation of the Mn oxidation state and dopant induced tiny Zn2MnO4/Mn2O3 and ZnMnO3/MnO2 impurities, which have not been detected by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM), were investigated by means of X-ray photoelectron spectroscopy (XPS), Raman scattering spectra, thermo-gravimetric analysis (TGA) and magnetic measurements. It is evidenced that the optimal Mn concentration x in ZnO to grow single phase Zn1-xMnxO should be below the cation percolation threshold xp (about 0.125), which is the basis to form real diluted magnetic semiconductors (DMSs).

Duan, Libing; Zhao, Xiaoru; Liu, Jinming; Geng, Wangchang; Xie, Haiyan; Chen, Shuai

2011-10-01

52

XRD and XPS characterisation of transition metal silicide thin films  

NASA Astrophysics Data System (ADS)

Binary transition metal silicides based on the systems Ti-Si, Fe-Si, Ni-Si and Cr-Si were fabricated on Si wafers by means of ion-beam co-sputter deposition and subsequent annealing. The crystalline structures of the phases formed were identified from the characteristic patterns acquired by means of X-ray diffraction (XRD) measurements. The phase formation sequences were described by means of the Pretorius' effective heat of formation (EHF) model. For the Ti-Si, Fe-Si and Ni-Si systems, single phase thin films of TiSi2, ?-FeSi2 and NiSi2 were generated as the model predicts, while a mixture of CrSi + CrSi2 phases was obtained for the Cr-Si system. The surface chemical condition of individual specimens was analysed by using X-ray photoelectron spectroscopy (XPS). The chemical shifts of transition metal 2p3/2 peaks from their metallic to silicide states were depicted by means of the Auger parameters and the Wagner plots. The positive chemical shift of 2.0 eV for Ni 2p3/2 peak of NiSi2 is mainly governed by the initial-state effects. For the other silicide specimens, the initial-state and final-state effects may oppose one another with similar impact. Consequently, smaller binding energy shifts of both negative and positive character are noted; a positive binding energy shift of 0.3 eV for the Fe 2p3/2 level was shown for ?-FeSi2 and negative binding energy shifts of 0.1 and 0.3 eV were determined for CrSi + CrSi2 and TiSi2, respectively.

Tam, P. L.; Cao, Y.; Nyborg, L.

2012-02-01

53

XRD studies of chitin-based polyurethane elastomers.  

PubMed

Chitin-based polyurethane elastomers (PUEs) were synthesized by step growth polymerization techniques using poly(epsilon-caprolactone) (PCL) varying diisocyanate and chain extender structures. The viscosity average molecular weight (M(v)) of chitin was deduced from the intrinsic viscosity and found; M(v)=6.067 x 10(5). The conventional spectroscopic characterization of the samples with FTIR, (1)H NMR and (13)C NMR were in accordance with proposed PUEs structure. The crystalline behavior of the synthesized polymers were investigated by X-ray diffraction (XRD), differential scanning calorimetery (DSC) and loss tangent curves (tan delta peaks). The observed patterns of the crystalline peaks for the lower angle for chitin in the 2theta range were indexed as 9.39 degrees, 19.72 degrees, 20.73 degrees, 23.41 degrees and 26.39 degrees. Results showed that crystallinity of the synthesized PUEs samples was affected by varying the structure of the diisocyanate and chain extender. Crystallinity decreased from aliphatic to aromatic characters of the diisocyanates used in the final PU. The presence of chitin also favors the formation of more ordered structure, as higher peak intensities was obtained from the PU extended with chitin than 1,4-butane diol (BDO). The value of peak enthalpy (DeltaH) of chitin was found to be 47.13 J g(-1). The higher DeltaH value of 46.35 J g(-1) was found in the samples extended with chitin than BDO (39.73 J g(-1)). PMID:18495239

Zia, Khalid Mahmood; Bhatti, Ijaz Ahmad; Barikani, Mehdi; Zuber, Mohammad; Sheikh, Munir Ahmad

2008-08-15

54

Chemical characterization of soot particles emitted by Wood-Burning Cook Stoves: A XPS and HRTEM study  

NASA Astrophysics Data System (ADS)

The morphology, microstructure, chemical composition, and electronic structure of soot particles emitted directly from biofuel cook stoves have been studied by high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). In order to obtain freshly emitted soot particles, 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 chain. Additionally, the morphology of soot particles was analyzed calculating the border-based fractal dimension (Df). Particles sampled on the first heating stage exhibit complex shapes with high values of Df, which are present as aggregates formed by carbon ceno-spheres. The XPS survey spectrum for soot particles shows that the main particle composition is carbon. We also observed differences in the carbon/oxygen (C/O) ratio of the particles, which probably depends on the combustion process efficiency of each cook-stove analyzed. The XPS C-1s spectra show carbon with two peaks that correspond to sp2 and sp3 hybridization. Also, real-time absorption (?a) and scattering (?s) coefficients of the particles emitted by cook stoves were measured. The trend in ?a and ?s 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.

Carabali, Giovanni; Peralta, Oscar; Castro, Telma; Torres, Ricardo; Ruiz, Gerardo; Molina, Luisa; Saavedra, Isabel

2014-05-01

55

Two-phase nc-TiN/a-(C,CN{sub x}) nanocomposite films: A HRTEM and MC simulation study  

SciTech Connect

The grain growth in two-phase nanocomposite Ti-C{sub x}-N{sub y} thin films grown by reactive close-field unbalanced magnetron sputtering in an Ar-N{sub 2} gas mixture with microstructures comprising of nanocrystalline (nc-) Ti(N,C) phase surrounded by amorphous (a-) (C,CN{sub x}) phase was investigated by a combination of high-resolution transmission electron microscopy (HRTEM) and Monte Carlo (MC) simulations. The HRTEM results revealed that amorphous-free solid solution Ti(C,N) thin films exhibited polycrystallites with different sizes, orientations and irregular shapes. The grain size varied in the range between several nanometers and several decade nanometers. Further increase of C content (up to {approx}19 at.% C) made the amorphous phase wet nanocrystallites, which strongly hindered the growth of nanocrystallites. As a result, more regular Ti(C,N) nanocrystallites with an average size of {approx}5 nm were found to be separated by {approx}0.5-nm amorphous phases. When C content was further increased (up to {approx}48 at.% in this study), thicker amorphous matrices were produced and followed by the formation of smaller sized grains with lognormal distribution. Our MC analysis indicated that with increasing amorphous volume fraction (i.e. increasing C content), the transformation from nc/nc grain boundary (GB)-curvature-driven growth to a/nc GB-curvature-driven growth is directly responsible for the observed grain growth from great inhomogeneity to homogeneity process.

Guo, J.; Lu, Y. H.; Hu, X. J.; Shen, Y. G. [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Kowloon (Hong Kong)

2013-06-18

56

Effect of crystallization on soft magnetic properties of nanocrystalline Fe80B10Si8Nb1Cu1 alloy  

NASA Astrophysics Data System (ADS)

The crystallization processes that occur in amorphous melt-spun ribbons of nominal composition Fe80B10Si8Nb1Cu1 during preparation and heat treatment affect the soft magnetic properties of this alloy. Fe80B10Si8Nb1Cu1 alloys are prepared by different quenching rates (wheel speeds of 10, 20 and 40 m/s) and their soft magnetic properties are studied. The XRD data reveal that as the wheel speed increases, the fraction of crystallinity and the Fe-Si grain size both decrease. These data also show that the sample prepared by the wheel speed of 10 m/s exhibits ?-Fe particles on its free surface. The data for the samples prepared by the wheel speed of 20 and 40 m/s are in good agreement with the HRTEM images. VSM measurements show that these nanostructured samples exhibit coercivity in the range of 3-21 A/m and magnetic saturation in the range of 1.55-1.78 T.

Hosseini-Nasb, Farzad; Beitollahi, Ali; Moravvej-Farshi, Mohammad Kazem

2015-01-01

57

Coaxial-electrospun magnetic core-shell Fe@TiSi nanofibers for the rapid purification of typical dye wastewater.  

PubMed

Magnetic mesoporous ?-Fe2O3@Ti0.9Si0.1O2 (abbreviated as Fe@TiSi) core-shell nanofibers were prepared using sol-gel chemistry combined with coaxial-electrospinning technology by adjusting the inner and outer feed ratios. The properties of these novel core-shell nanofibers were characterized by SEM, HRTEM, XRD, FTIR, BET, XPS, and UV-vis spectra. To evaluate the chemical properties of the nanofibers for cleaning typical organic wastewater, methylene blue (MB) was used as a target organic pollutant and was cleaned under irradiation with sunlight and visible light. The Fe@TiSi hierarchical nanofibers composed of a 1:10 feed ratio displayed a mesoporous structure and showed the highest photocatalytic activity for the degradation of MB in water. Furthermore, 86.8% and 71.1% of the MB, which was added at an original concentration of 1 mg/L, was removed after 60 min of irradiation with sunlight and visible light in the presence of Fe@TiSi at a concentration of 0.2 g/L, and 100% of the MB was removed after 75 min. It is very important that the magnetic nanofibers could be recycled rapidly with an outside magnet, and the actual water treatment process was easy to achieve. Moreover, the mechanism of MB degradation by Fe@TiSi core-shell nanofibers was proposed. PMID:25226354

Zhan, Sihui; Zhu, Dandan; Ren, Guangyuan; Shen, Zhiqiang; Qiu, Mingying; Yang, Shanshan; Yu, Hongbing; Li, Yi

2014-10-01

58

Interplay of bulk and surface on the magnetic properties of low temperature synthesized nanocrystalline cubic Cu1-xZnxFe2O4 (x=0.00, 0.02, 0.04 and 0.08)  

NASA Astrophysics Data System (ADS)

Synthesis of Cu1-xZnxFe2O4, (x=0.00, 0.02, 0.04 and 0.08) nanoparticles by a low-temperature combustion method is achieved and its structural and magnetic characterizations are performed. X-ray powder diffraction (XRD) study and high resolution transmission electron microscope (HRTEM) images confirm the formation of single cubic phase of nanocrystalline copper ferrite. The inter-planar spacing (d) and particle size increases with increasing Zn content. Cation distribution of mixed spinel Cu1-xZnxFe2O4 nanoparticles are estimated by Fourier transformed infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and further verified by 57Fe Mo¨ssbauer spectroscopy. Detailed magnetic properties are studied by means of Field Cooled (FC) - Zero Field Cooled (ZFC) magnetization measurements and hysteresis loops at various temperatures by the physical property measurement system (PPMS). A transition from superparamagnetic state to ferrimagnetic state is observed as the Zn concentration increases in Cu1-xZnxFe2O4 nanoparticles. The temperature dependence of intrinsic magnetic parameters, i.e., coercivity (HC), saturation magnetization (MS), effective anisotropy constant (Keff) and paramagnetic susceptibility (?p) of Cu1-xZnxFe2O4 reveals the existence of low-temperature spin-glass-like state, which is more prominent for smaller particles and starts to disappear with increasing Zn concentration.

Chatterjee, Biplab K.; Dey, Abhishek; Ghosh, Chandan K.; Chattopadhyay, Kalyan K.

2014-10-01

59

In situ synthesis and characterization of magnetic nanoparticles in shells of biodegradable polyelectrolyte microcapsules.  

PubMed

Hollow microcapsules with the shell composed of biodegradable polyelectrolytes modified with the maghemite nanoparticles were fabricated by in situ synthesis. The nanoparticles were synthesized from the iron salt and the base directly on the capsule shells prepared by "layer by layer" technique. An average diameter of the capsule was about 6.7 ?m while the average thickness of the capsule shell was 0.9 ?m. XRD, HRTEM, Raman and Mössbauer spectroscopy data revealed that the iron oxide nanoparticles have the crystal structure of maghemite ?-Fe2O3. The nanoparticles were highly monodisperse with medium size of 7.5 nm. The Mössbauer spectroscopy data revealed that the nanoparticles have marked superparamagnetic behavior which was retained up to room temperature due to slow spin relaxation. Because of that, the microcapsules can be handled by an external magnetic field. Both these properties are important for target drug delivery. Based on the Mössbauer spectroscopy data, the spin blocking temperatures TB of about 90K was found for the particles with size D?5 nm and TB?250 K for particles with D?6 nm. The anisotropy constants K were determined using the superparamagnetic approximation and in the low temperature approximation of collective magnetic excitation. PMID:25491824

Lyubutin, I S; Starchikov, S S; Bukreeva, T V; Lysenko, I A; Sulyanov, S N; Korotkov, N Yu; Rumyantseva, S S; Marchenko, I V; Funtov, K O; Vasiliev, A L

2014-12-01

60

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

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

61

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

SciTech Connect

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.

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

2014-10-01

62

Raman, XRD and positron study of ferroelectric films  

NASA Astrophysics Data System (ADS)

Ferroelectric thin films have important applications in electronic memory, infrared sensor, piezoelectric sensors and actuators. In this work, ferroelectric properties of metalorganic decomposition derived PbZrxTi 1-xO3 (PZT), Bi4Ti 3O12 (BIT) and Bi4-xLa xTi3O12 (LBIT) thin films deposited onto Pt(111)/Ti/SiO2/Si(100) substrates were studied. The thin films were studied using x-ray diffraction, scanning electron microscopy, Raman scattering, positron annihilation spectroscopy and x-ray photoelectron spectroscopy methods. The ferroelectric properties and the orientation dependence of these properties in PZT and LBIT thin films were determined by hysteresis measurements. The polarization and coercive field increase with (111) orientation in PZT and are due to the orientation of the unit cell. The dielectric constant and polarization increase with non-c-orientation in LBIT thin films. This is due to the major polarization vector of LBIT which lies along the a/b plane. Through controlling heating rate the orientation and the orientation-dependent polarization properties can be controlled. This is because increase of heating rate increases (111) orientation in PZT and c-orientation of LBIT. Also, doping (increase of Zr content in PZT) tends to increase (111) orientation, and La doping in LBIT tends to increase non-c-orientation. In addition, grain size can affect the polarization properties. Small grains possess better polarization properties than large grains which usually have defects. Ferroelectricity can be affected by very small grains due to the internal stress. The Raman study showed an orientation and grain-size dependence of the Raman modes. The XRD study shows that the PZT has a change of strain after fatigue. The change of strain is due to the change between the 90° and 180° domains. Raman study shows that fatigue reduces the Raman intensity and crystallinity. Positron annihilation depth-profile indicates a change of defect concentration at the surface. The defect can be attributed to uncompensated oxygen vacancies. The removal of oxygen after fatigue is suggested by XPS study. Thus fatigue in PZT can be due to oxygen vacancies and strain which is due to the change of 90° to 180° domains. For LBIT thin films, Raman study shows that La doping changes the O-Ti-O bending symmetry which is important for ferroelectric polarization. Positron annihilation study shows the change in defect concentration with La doping is not significant. XPS study does not show significant removal of oxygen. Thus the improvement in ferroelectric properties by La doping is due to the lattice symmetry and not defect concentrations. This is consistent with the fact that isovalent doping does not induce a defect concentration change.

Yau, Chiyat Ben

63

Direct observation of extended dislocation in Cd0.9Zn0.1Te single crystals by HRTEM  

NASA Astrophysics Data System (ADS)

The core structure of extended dislocation in Cd0.9Zn0.1Te was observed by high resolution transmission electron microscopy (HRTEM). The dissociate mechanism of basal dislocation in Cd0.9Zn0.1Te was studied by using Digital Micrograph (DM) software. Furthermore, stacking fault energy of Cd0.9Zn0.1Te single crystal was calculated to be 9.17 mJ/m2 which is lower compared with the semiconductors with diamond structures, such as Si and Ge. The reason of low stacking fault energy of Cd0.9Zn0.1Te was investigated to be the increase of the fractional ionicity of the bonding by using Phillips theory.

Sun, Jie; Fu, Li

2012-08-01

64

Magnetism  

NSDL National Science Digital Library

This webpage is part of the University Corporation for Atmospheric Research (UCAR) Windows to the Universe program. It describes the nature and configuration of magnetic fields, which are the result of moving electric charges, including how they cause magnetic objects to orient themselves along the direction of the magnetic force points, which are illustrated as lines. Magnetic field lines by convention point outwards at the north magnetic pole and inward at the south magnetic pole. The site features text, scientific illustrations and an animation. Text and vocabulary are selectable for the beginning, intermediate, or advanced reader.

Team, University C.

2007-12-12

65

Effect of sintering pressure on structure and magnetic properties of Zn0.99Ni0.01O bulk samples synthesized under different pressures  

NASA Astrophysics Data System (ADS)

A series of Zn0.99Ni0.01O bulk samples were prepared by a coprecipitation method, and then sintered at 600 °C under various pressures from normal pressure(NP) to 3 GPa. The effects of sintering pressure (PS) on the structure, morphology and magnetic properties of the doping samples were investigated in detail. The XRD and HRTEM results reveal that all samples are of single-phase hexagonal structure. Compared with the sample sintered at normal pressure, the lattice parameters a and c of the samples sintered at high pressures (HP) show a sharply decrease. With the increase of sintering pressure, the particle size gradually increases as well as the particles get closer to each other. At 300 K, the sample sintered at normal pressure shows a superparamagnetic-like behavior, while the samples sintered at high pressures display typical ferromagnetic behaviors. The saturation magnetization of the samples sintered at high pressures is three orders of magnitude larger than that of the one sintered at normal pressure. Our results reveal that an appropriate sintering pressure can tune the magnetic properties of Ni-doped ZnO system by changing the lattice parameters, particle size and inter-particle spacing, which may be helpful to the practical applications.

Wang, Yongqiang; Yuan, Chaosheng; Su, Lei; Wang, Zheng; Hao, Junhong; Ren, Yufen

2015-01-01

66

Equilibrium and kinetic studies on acid dye Acid Red 88 adsorption by magnetic ZnFe2O4 spinel ferrite nanoparticles.  

PubMed

A magnetic ZnFe2O4 (MNZnFe) was synthesized by microwave assisted hydrothermal method and was used as an adsorbent for the removal of acid dye Acid Red 88 (AR88) from aqueous solution. The effects of various parameters such as initial AR88 concentration (10-56 mg L(-1)), pH solution (3.2-10.7), and temperature (20-60°C) were investigated. Prepared magnetic ZnFe2O4 was characterized by XRD, SEM, HRTEM, ICP-AES, BET, FTIR, and measurements of the magnetic susceptibility. The experimental data were analyzed by the Langmuir and Freundlich models of adsorption. Equilibrium data fitted well with the Langmuir model. Pseudo-first-order and pseudo-second-order kinetic models and intraparticle diffusion model were used to examine the adsorption kinetic data. The adsorption kinetics was found to follow the pseudo-second-order kinetic model. Thermodynamics parameters, ?G°, ?H° and ?S°, indicate that the adsorption of AR88 onto MNZnFe was spontaneous and exothermic in nature. PMID:23506747

Konicki, Wojciech; Sibera, Daniel; Mijowska, Ewa; Lendzion-Bielu?, Zofia; Narkiewicz, Urszula

2013-05-15

67

Magnetism  

NSDL National Science Digital Library

This radio broadcast discusses the history of magnetism from the time of its discovery by an apocryphal Greek sheperd until the late 16th century and the work of William Gilbert. There is also discussion of who pioneered the study of magnetism, what theories they constructed from its curious abilities, and how the power of the magnet was brought out of the realm of magic and into the service of science. The broadcast concludes with a discussion of why magnetism is still mysterious and how the modern search for the single magnetic pole, or magnetic monopole, could provide a fundamental unit of magnetism, essential for ultimate explanation. The broadcast is 41 minutes and 45 seconds in length.

68

Development Of Magnetic FeatC Nanocomposites Obtained Via The Laser Pyrolysis: Structural And Disaggregation Properties  

Microsoft Academic Search

FeatC) nanoparticles have been successfully synthesized using the laser pyrolysis method and variable nozzle geometries. At large nozzle diameters, XRD and SAED analysis clearly identified distinct alpha-Fe and Fe3C phases. TEM and HRTEM indicated that these Fe-based nanoparticles have an average grain size of 3.5-10.2 nm. Temperature dependent Mössbauer spectra further confirm their distinct nanophases. By using a multi-step reduction

Ion Morjan; R. Alexandrescu; F. Dumitrache; C. Fleaca; R. Birjega; I. Soare; C.-R. Luculescu; V. Prodan; V. Kuncser; G. Filoti; H. Xu; D. Wang

2010-01-01

69

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

PubMed

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

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

2013-11-15

70

Practical aspects of the use of the X(2) holder for HRTEM-quality TEM sample preparation by FIB.  

PubMed

The X(2) holder enables the effective production of thin, electron transparent samples for high-resolution transmission electron microscopy (HRTEM). Improvements to the X(2) holder for high-quality transmission electron microscopy (TEM) sample preparation are presented in this paper. We discuss the influence of backscattered electrons (BSE) from the sample holder in determining the lamella thickness in situ and demonstrate that a significant improvement in thickness determination can be achieved by comparatively simple means using the relative BSE intensity. We show (using Monte Carlo simulations) that by taking into account the finite collection angle of the electron backscatter detector, an approximately 20% underestimation of the lamella thickness in a silicon sample can be avoided. However, a correct thickness determination for light-element lamellas still remains a problem with the backscatter method; we introduce a more accurate method using the energy dispersive X-ray spectroscopy (EDX) signal for in situ thickness determination. Finally, we demonstrate how to produce a thin lamella with a nearly damage-free surface using the X(2) holder in combination with sub-kV polishing in the Fischione Instruments? NanoMill(®) TEM specimen preparation system. PMID:25194827

van Mierlo, Willem; Geiger, Dorin; Robins, Alan; Stumpf, Matthias; Ray, Mary Louise; Fischione, Paul; Kaiser, Ute

2014-12-01

71

Microstructure\\/magnetic property relationships in CoCrPt magnetic thin films  

Microsoft Academic Search

Microstructural investigations of CoCrPt\\/Cr and CoCrPt\\/CrV magnetic thin film media were conducted in order to explain improved media performance as a function of increased Cr concentration in the magnetic layer and a predeposition treatment of the NiP plated Al substrate. Using High Resolution Transmission Electron Microscopy (HRTEM) and Selected Area Diffraction Patterns (SADP) it was found that for both underlayer

S. E. McKinlay; N. Fussing; R. Sinclair

1996-01-01

72

X-ray Diffraction (XRD) 1.0 What is X-ray Diffraction  

E-print Network

X-ray Diffraction (XRD) · 1.0 What is X-ray Diffraction · 2.0 Basics of Crystallography · 3.0 Production of X-rays · 4.0 Applications of XRD · 5.0 Instrumental Sources of Error · 6.0 Conclusions #12 why the cleavage faces of crystals appear to reflect X-ray beams at certain angles of incidence (theta

Moeck, Peter

73

Magnetism  

NSDL National Science Digital Library

This overview of magnetism provides a brief history prior to 1600 and continues with the work of William Gilbert, Hans Christian Oersted, and Andre-Marie Ampere in describing and exploring the magnetosphere and learning the role that electric current plays in producing magnetism. Magnetic field lines are then discussed, citing the work of Michael Faraday. The work of James Clerk Maxwell and Heinrich Hertz is mentioned in a discussion of the relationship of light waves and radio waves as part of the electromagnetic spectrum.

Stern, David

74

HRTEM in protein crystallography  

NASA Astrophysics Data System (ADS)

Electron microscopy/diffraction (ED/D) using spot-scan and low-dose imaging has been successfully applied to investigate microcrystals of an alpha-helical coiled-coil protein extracted from ootheca of the praying mantis. Fourier transforms of the images show resolution out to 4 A and can be used to phase the corresponding ED data which shows reflections out to 2 A.

Dyson, P. W.; Spargo, A. E. C.; Tulloch, P. A.; Johnson, A. W. S.

75

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

Microsoft Academic Search

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 ZnMnO3 impurity phase was formed in the 20% and

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

2010-01-01

76

Improved magnetic and ferroelectric properties of Sc and Ti codoped multiferroic nano BiFeO? prepared via sonochemical synthesis.  

PubMed

The room temperature multiferroic properties of bulk BiFeO3 are not exciting enough for its application in devices. Here, we report the sonochemical synthesis of scandium and titanium codoped BiFeO3 nanoparticles which exhibit improved magnetic and ferroelectric properties at room temperature. The nanoparticles have been checked for phase purity and composition using powder X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). The size and morphology of the nanoparticles have been confirmed using scanning electron microscopy (SEM), and both low and high resolution transmission electron microscopy (TEM/HRTEM). The breaking of the spin cycloid due to the smaller size and slight structural distortion caused by the doping has been found to be instrumental for the enhancement of multiferroic properties. The electrical polarization increases significantly in the case of BiFe(0.925)Sc(0.05)Ti(0.025)O3 nanoparticles. A marked reduction in the leakage current was seen compared to undoped BiFeO3. Magnetoelectric coupling was also observed in the BiFe(0.925)Sc(0.05)Ti(0.025)O3 sample. Our results demonstrate that codoping with Sc and Ti ions is an effective way to rectify and enhance the multiferroic nature of BiFeO3. PMID:24705584

Dutta, Dimple P; Mandal, B P; Mukadam, M D; Yusuf, S M; Tyagi, A K

2014-06-01

77

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

SciTech Connect

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.

Don Pellinen and Michael Griffin

2009-01-23

78

The thermal behaviour of cuprite: An XRD-EXAFS combined approach  

NASA Astrophysics Data System (ADS)

Cuprite (Cu 2O) is a low thermal expansion material with a negative thermal expansion coefficient below room temperature. Its peculiar thermal behaviour encompasses the increase of the shear modulus with increasing temperature, and the presence of rather intense symmetry-forbidden eeo reflections below room temperature. The thermal expansion of cuprite was studied at low temperature (between 5 and 298 K) by means of high-resolution (10 -5 Å) X-ray powder diffraction at European Synchrotron Radiation Facility (Grenoble, BM16) and extended X-ray absorption fine structure (EXAFS) (BM29). Negative thermal expansion is confirmed up to 200 K, by EXAFS as well as by XRD measurements, and no sign of transition was found in XRD data. The comparison between EXAFS and XRD results provides a valuable insight into vibrational behaviour of cuprite at low temperature.

Dapiaggi, M.; Tiano, W.; Artioli, G.; Sanson, A.; Fornasini, P.

2003-01-01

79

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

SciTech Connect

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.

Kane, Sanjeev R.; Garg, C. K.; Sinha, A. K. [Indus Synchrotron Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore-452013 (India)

2010-06-23

80

Effect of annealing temperature on the structural, photoluminescence and magnetic properties of sol-gel derived Magnetoplumbite-type (M-type) hexagonal strontium ferrite  

Microsoft Academic Search

Magnetoplumbite-type (M-type) hexagonal strontium ferrite particles were synthesized via sol-gel technique employing ethylene glycol as the gel precursor at two different calcination temperatures (800 and 1000 °C). Structural properties were systematically investigated via X-ray diffraction (XRD), field emission scanning electron microscopy, high resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), photoluminescence spectrophotometry and superconducting quantum interference

Geok Bee Teh; Yat Choy Wong; Richard D. Tilley

2011-01-01

81

Effect of annealing temperature on the structural, photoluminescence and magnetic properties of sol–gel derived Magnetoplumbite-type (M-type) hexagonal strontium ferrite  

Microsoft Academic Search

Magnetoplumbite-type (M-type) hexagonal strontium ferrite particles were synthesized via sol–gel technique employing ethylene glycol as the gel precursor at two different calcination temperatures (800 and 1000°C). Structural properties were systematically investigated via X-ray diffraction (XRD), field emission scanning electron microscopy, high resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), photoluminescence spectrophotometry and superconducting quantum interference device

Geok Bee Teh; Yat Choy Wong; Richard D. Tilley

2011-01-01

82

Effect of Seed Layer on Room Temperature Tunnel Magnetoresistance of MgO Barriers Formed by Radical Oxidation in IrMn-Based Magnetic Tunnel Junctions  

NASA Astrophysics Data System (ADS)

NiFe-seeded magnetic tunnel junctions (MTJs) of IrMn/CoFe/MgO/CoFeB were successfully formed by radically oxidizing a thin Mg layer. Room temperature (RT) tunnel magnetoresistance (TMR) of up to 211±10% was obtained and found to be strongly dependent on the thickness of the NiFe seed layer. High resolution transmission microscopy (HRTEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and magneto-optic Kerr effect (MOKE) analyses performed on NiFe/IrMn bilayer systems revealed that the IrMn(111)-fcc texture, grain size, surface roughness (rms), and exchange-biasing field (Hex) were strongly affected by the thickness of the NiFe seed layer. A critical NiFe thickness (tc ?12 Å) was found: For tNiFe?tc, the IrMn showed a very poor (111)-fcc texture with reduced grain size, very smooth surface, and reduced Hex. For tNiFe > tc, the IrMn showed a complete opposite behavior: much enhanced (111)-fcc texture with larger grain size, rougher surface, and larger Hex. For MTJ-based IrMn systems, a striking behavior is reported: larger TMRs and lower tunnel junction resistance (RA) products are obtained for tNiFe ?tc while lower TMRs and larger RAs are obtained for tNiFe > tc.

Dahmani, Faiz

2012-04-01

83

Highly ordered magnetic mesoporous silicas for effective elimination of carbon monoxide  

SciTech Connect

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.

Lee, Jiho [Korea Institute of Ceramic Engineering and Technology, Seoul 153-801 (Korea, Republic of); Department of Chemistry, Inha University, Incheon 402-751 (Korea, Republic of); Ho Chang, Jeong, E-mail: jhchang@kicet.re.kr [Korea Institute of Ceramic Engineering and Technology, Seoul 153-801 (Korea, Republic of)

2012-04-15

84

Dissolution of nanocrystalline fluorite powders: An investigation by XRD and solution chemistry  

NASA Astrophysics Data System (ADS)

The effect of lattice disorder and mineral surface area on the reactivity of finely ground fluorite was studied on ball-milled powders. Structural information was provided by X-ray whole powder pattern modeling (WPPM). The mean size of coherent scattering domains decreases with milling time from 70 nm to ˜20 nm, whereas the density of lattice defects increases with both time and intensity of milling treatment, from 4 × 10 15 m -2 to 24 × 10 15 m -2. High resolution transmission electron microscopy (HRTEM) of ground fluorite grains shows several line defects and a general tendency of nanometric crystalline domains to agglomerate in larger grains. Solution chemistry was investigated using batch reactors with free drift of solution saturation state with respect to fluorite. Total surface area was measured by the Brunaver, Emmet and Teller (BET) method, and dissolution rates were measured at pH = 2 (HCl) and T = 295 K. In far from equilibrium conditions, dissolution rates normalized by BET area do not increase with the dislocation density. In near-equilibrium condition, however, measured stationary ionic product clearly increases with both time and intensity of milling treatment. Thermodynamic predictions of the solubility constant indicate negligible or little effect of total surface area. Consequently, the observed increase in the stationary ionic product can be related to the increasing lattice defect content. This confirms the significant role of dislocation outcrops on mineral dissolution in close to equilibrium conditions.

De Giudici, Giovanni; Biddau, Riccardo; D'incau, Mirco; Leoni, Matteo; Scardi, Paolo

2005-08-01

85

Characterization of diamond-like carbon films by SEM, XRD and Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Diamond-like carbon films were deposited by electrolysis of a water-ethanol solution on Cu at low voltages (60-100 V) at 2 mm interelectrode separation. The films were characterized by scanning electron microscopy (SEM), X-ray diffractometer (XRD) and Raman spectroscopy. The films were found to be continuous and compact with uniform grain distribution. Raman spectroscopy analysis revealed two broad bands at ˜1350 and ˜1580 cm -1. The downshift of the G band of graphite is indicative of the presence of DLC. For XRD analysis, the three strong peaks located at 2 ? values of 43.2°, 74.06° and 89.9° can be identified with reflections form (1 1 1), (2 2 0) and (3 1 1) plane of diamond.

Pang, Hua; Wang, Xingquan; Zhang, Guling; Chen, Huan; Lv, Guohua; Yang, Size

2010-08-01

86

Understanding changes in cellulose crystalline structure of lignocellulosic biomass during ionic liquid pretreatment by XRD.  

PubMed

X-ray diffraction (XRD) was used to understand the interactions of cellulose in lignocellulosic biomass with ionic liquids (ILs). The experiment was designed in such a way that the process of swelling and solubilization of crystalline cellulose in plant cell walls was followed by XRD. Three different feedstocks, switchgrass, corn stover and rice husk, were pretreated using 1-butyl-3-methylimidazolium acetate ([C4mim][OAc]) at temperatures of 50-130°C for 6h. At a 5 wt.% biomass loading, increasing pretreatment temperature led to a drop in biomass crystallinity index (CrI), which was due to swelling of crystalline cellulose. After most of the crystalline cellulose was swollen with IL molecules, a low-order structure was found in the pretreated samples. Upon further increasing temperature, cellulose II structure started to form in the pretreated biomass samples as a result of solubilization of cellulose in [C4mim][OAc] and subsequent regeneration. PMID:24269347

Zhang, Jiafu; Wang, Yixun; Zhang, Liye; Zhang, Ruihong; Liu, Guangqing; Cheng, Gang

2014-01-01

87

TEM, XRD and nanoindentation characterization of Xenon ion irradiation damage in austenitic stainless steels  

NASA Astrophysics Data System (ADS)

Cross-sectional and bulk specimens of a 20% cold-worked 316 austenitic stainless steel (CW 316 SS) has been characterized by TEM, XRD and nanoindentation to determine the microstructural evolution and mechanical property changes of 316 SS after irradiation with 7 MeV Xe26+ ions. TEM results reveal the presence of dislocation loops with a number density of approximately 3 × 1022 m-3 and sizes between 3 to 10 nm due to the collapse of vacancy rich cores inside displacement cascades. Peak broadening observed in XRD diffraction patters reveal systematic changes to lattice parameters due to irradiation. The calculated indentation values in irradiated 316 SS were found to be much higher in comparison to the unirradiated specimen, indicating the dose dependent effect of irradiation on hardness. The relationship between irradiation induced microstructural evolution and the changes to the mechanical properties of CW 316 SS are discussed in the context of fluence and irradiation temperature.

Huang, H. F.; Li, J. J.; Li, D. H.; Liu, R. D.; Lei, G. H.; Huang, Q.; Yan, L.

2014-11-01

88

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

SciTech Connect

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.

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

2012-01-03

89

Growth, XRD and dielectric properties of triglycine sulpho-phosphate (TGSP) crystals added with magnesium sulfate  

Microsoft Academic Search

Pure and magnesium sulfate-doped triglycine sulpho-phosphate (TGSP) single crystals were grown by solution method with the slow evaporation technique. Solubility of the samples in de-ionized water was found in various temperatures ranging from 30 to 60 °C. Single-crystal X-ray diffraction (XRD) studies on the grown crystals reveal the monoclinic crystal structure. Atomic absorption study (AAS) was carried out to confirm

P. Selvarajan; A. Siva Dhas; T. H. Freeda; C. K. Mahadevan

2008-01-01

90

Growth, XRD and dielectric properties of triglycine sulpho-phosphate (TGSP) crystals added with magnesium sulfate  

Microsoft Academic Search

Pure and magnesium sulfate-doped triglycine sulpho-phosphate (TGSP) single crystals were grown by solution method with the slow evaporation technique. Solubility of the samples in de-ionized water was found in various temperatures ranging from 30 to 60°C. Single-crystal X-ray diffraction (XRD) studies on the grown crystals reveal the monoclinic crystal structure. Atomic absorption study (AAS) was carried out to confirm the

P. Selvarajan; A. Siva dhas; T. H. Freeda; C. K. Mahadevan

2008-01-01

91

Nanosecond magnetization reversal in nanocrystalline magnetic films  

NASA Astrophysics Data System (ADS)

This paper reports on the investigation of dynamic magnetization reversal process in electrodeposited nanocrystalline Ni and Ni80Fe20 films by employing nanosecond magnetic pulse technique. The surface morphology has been investigated using SEM, EDAX, XRD and AFM analyses and static magnetic properties of the films are characterized by vibrating sample magnetometer (VSM). Two different techniques are designed and employed to study the nanosecond magnetization reversal process in nanocrystalline thin films: Magneto-Optical Kerr Effect (MOKE) and nanosecond pulsed field magnetometer. Results of dynamical behavior as a function of several variables such as magnitude of applied bias magnetic field, amplitude and width of the pulsed magnetic field are analyzed in detail using both techniques. A computer simulation package called Object Oriented Micro-Magnetic Framework (OOMMF) has been used to simulate the magnetic domain patterns of the samples.

Rahman, I. Z.; Gandhi, A. A.; Khaddem-Mousavi, M. V.; Lynch, T. F.; Rahman, M. A.

2007-03-01

92

Matching 4.7-Å XRD spacing in amelogenin nanoribbons and enamel matrix.  

PubMed

The recent discovery of conditions that induce nanoribbon structures of amelogenin protein in vitro raises questions about their role in enamel formation. Nanoribbons of recombinant human full-length amelogenin (rH174) are about 17 nm wide and self-align into parallel bundles; thus, they could act as templates for crystallization of nanofibrous apatite comprising dental enamel. Here we analyzed the secondary structures of nanoribbon amelogenin by x-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) and tested if the structural motif matches previous data on the organic matrix of enamel. XRD analysis showed that a peak corresponding to 4.7 Å is present in nanoribbons of amelogenin. In addition, FTIR analysis showed that amelogenin in the form of nanoribbons was comprised of ?-sheets by up to 75%, while amelogenin nanospheres had predominantly random-coil structure. The observation of a 4.7-Å XRD spacing confirms the presence of ?-sheets and illustrates structural parallels between the in vitro assemblies and structural motifs in developing enamel. PMID:25048248

Sanii, B; Martinez-Avila, O; Simpliciano, C; Zuckermann, R N; Habelitz, S

2014-09-01

93

Mineralogical composition of the meteorite El Pozo (Mexico): a Raman, infrared and XRD study.  

PubMed

The Raman (RMP), infrared (IR) and XRD analysis have been applied to the examination of mineralogical composition of El Pozo meteorite (an ordinary chondrite L5 type; village Valle of Allende, founded in State of Chihuahua, Mexico: 26°56'N and 105°24'W, 1998). RMP measurements in the range of 100-3500 cm(-1) revealed principal characteristic bands of the major minerals: olivine, two polymorph modifications of pyroxene (OPx and CPx) and plagioclase. Some bands of the minor minerals (hematite and goethite) were also identified. All these minerals were clearly distinguished using IR and XRD techniques. XRD technique has shown the presence of some metallic phases such as kamacite and taenite as well as troilite and chromite. These minerals do not have characteristic Raman spectra because Fe-Ni metals have no active modes for Raman spectroscopy and troilite is a weak Raman scatterer. Raman mapping microspectroscopy was a key part in the investigation of El Pozo meteorite's spatial distribution of the main minerals because these samples are structurally and chemically complex and heterogeneous. The mineral mapping by Raman spectroscopy has provided information for a certain spatial region on which a spatial distribution coexists of the three typical mineral assemblages: olivine; olivine+orthopyroxene; and orthopyroxene. PMID:21930423

Ostrooumov, Mikhail; Hernández-Bernal, Maria del Sol

2011-12-01

94

Mineralogical composition of the meteorite El Pozo (Mexico): A Raman, infrared and XRD study  

NASA Astrophysics Data System (ADS)

The Raman (RMP), infrared (IR) and XRD analysis have been applied to the examination of mineralogical composition of El Pozo meteorite (an ordinary chondrite L5 type; village Valle of Allende, founded in State of Chihuahua, Mexico: 26°56'N and 105°24'W, 1998). RMP measurements in the range of 100-3500 cm -1 revealed principal characteristic bands of the major minerals: olivine, two polymorph modifications of pyroxene (OPx and CPx) and plagioclase. Some bands of the minor minerals (hematite and goethite) were also identified. All these minerals were clearly distinguished using IR and XRD techniques. XRD technique has shown the presence of some metallic phases such as kamacite and taenite as well as troilite and chromite. These minerals do not have characteristic Raman spectra because Fe-Ni metals have no active modes for Raman spectroscopy and troilite is a weak Raman scatterer. Raman mapping microspectroscopy was a key part in the investigation of El Pozo meteorite's spatial distribution of the main minerals because these samples are structurally and chemically complex and heterogeneous. The mineral mapping by Raman spectroscopy has provided information for a certain spatial region on which a spatial distribution coexists of the three typical mineral assemblages: olivine; olivine + orthopyroxene; and orthopyroxene.

Ostrooumov, Mikhail; Hernández-Bernal, Maria del Sol

2011-12-01

95

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

PubMed

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

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

2007-11-01

96

Effect of FeCl3 and acetone on the structure of Na-montmorillonite studied by Mössbauer and XRD measurements  

NASA Astrophysics Data System (ADS)

57Fe Mössbauer spectroscopy, X-ray diffraction, X-ray fluorescence spectroscopy and infrared spectroscopy were used to study the effect of FeCl3 and acetone on the structure of a Na-bentonite. XRD indicated the incorporation of Fe3+ ions into the interlayer space since the basal lattice spacing of montmorillonite increased to 1.6 from 1.24 nm after treatment with FeCl3 dissolved in acetone. Interlayer Na+ ions could be exchanged to Fe3+. Magnetically split Mössbauer subspectra with internal magnetic fields 41 and 46 T at 74 K, were associated with two main Fe3+ microenvironments within the interlayer regions. The resultant Fe-montmorillonite was successfully applied as a catalyst in the preparation of 1,1-diacetates from aromatic aldehydes and acetic acid anhydride.

Komlósi, Andrea; Kuzmann, Ern?; Homonnay, Zoltán; Nagy, Noémi M.; Kubuki, Shiro; Kónya, József

2005-11-01

97

Copper(0) nanoparticles supported on silica-coated cobalt ferrite magnetic particles: cost effective catalyst in the hydrolysis of ammonia-borane with an exceptional reusability performance.  

PubMed

Herein we report the development of a new and cost-effective nanocomposite catalyst for the hydrolysis of ammonia-borane (NH(3)BH(3)), which is considered to be one of the most promising solid hydrogen carriers because of its high gravimetric hydrogen storage capacity (19.6% wt) and low molecular weight. The new catalyst system consisting of copper nanoparticles supported on magnetic SiO(2)/CoFe(2)O(4) particles was reproducibly prepared by wet-impregnation of Cu(II) ions on SiO(2)/CoFe(2)O(4) followed by in situ reduction of the Cu(II) ions on the surface of magnetic support during the hydrolysis of NH(3)BH(3) and characterized by ICP-MS, XRD, XPS, TEM, HR-TEM and N(2) adsorption-desorption technique. Copper nanoparticles supported on silica coated cobalt(II) ferrite SiO(2)/CoFe(2)O(4) (CuNPs@SCF) act as highly active catalyst in the hydrolysis of ammonia-borane, providing an initial turnover frequency of TOF = 2400 h(-1) at room temperature, which is not only higher than all the non-noble metal catalysts but also higher than the majority of the noble metal based homogeneous and heterogeneous catalysts employed in the same reaction. More importantly, they were easily recovered by using a permanent magnet in the reactor wall and reused for up to 10 recycles without losing their inherent catalytic activity significantly, which demonstrates the exceptional reusability of the CuNPs@SCF catalyst. PMID:22856878

Kaya, Murat; Zahmakiran, Mehmet; Ozkar, Saim; Volkan, Mürvet

2012-08-01

98

High resolution transmission electron microscopy (HRTEM) of interfaces in epitaxial ZnSe yS 1 - y grown by MOCVD  

NASA Astrophysics Data System (ADS)

The preparation of cross-sectional samples of a number of epitaxially grown, binary and ternary materials within the system ZnSe 1 - yS y (0 ? y ? 1) on a variety of single crystalline substrates is reported. A combination of chemical polishing and fast atom bombardment (FAB) provides samples down to ca. ? 100 Å thickness and these are suitable for study by high resolution (lattice imaging) transmission electron microscopy (HRTEM). The integrity of the structure and composition of epitaxial layers appears to be maintained during thinning and our techniques allow the selection and subsequent thinning of particular regions of interfaces. The lattice images obtained at 100 and 120 keV reveal structural details of the interfaces and defects in the bulk of the epiaxial layers.

Williams, J. O.; Ng, T. L.; Wright, A. C.; Cockayne, B.; Wright, P. J.

1984-09-01

99

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

SciTech Connect

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.

Cady, S.L.; Wenk, H.R. (Univ. of California, Berkeley, CA (United States))

1992-01-01

100

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

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

101

Titanium dioxide (TiO2) Nanoparticles XRD Analyses: An Insight  

E-print Network

This work reports aspect related to nano-sized particles of tetragonal anatase phase Titania. This approach is simple, faster, Eco-friendly, cost effective and suitable for large scale production. X-Ray Diffraction studies analyze particles size. It is found to be 74 nm and specific surface area is 19.16m2g-1. Morphology index (MI) derived from FWHM of XRD data explains the interrelationship of particle size and specific surface area. It is observed that MI has direct relationship with particle size and an inverse relationship with specific surface area. This work throws some light on and helps in the production line of Titania nano-particles.

Theivasanthi, T

2013-01-01

102

Hydration Characteristics of Metakaolin Admixtured Cement using DTA, XRD and SEM Techniques  

NASA Astrophysics Data System (ADS)

The paper aims to investigate hydration and pozzolanic reaction in Portland cement paste with different replacement percentages (0%, 10%, 20% and 30%) of metakaolin. The compressive strength of the metakaolin admixtured cement was measured at 1 day, 1 week and 4 weeks. The compressive strength developments of the metakaolin admixtured cement are compared with Portland cement. It is found that metakaolin contributes significantly to strength development as an accelerating admixture for Portland cement. The pozzolanic reactions and the reaction products were determined by DTA, XRD and SEM.

Govindarajan, D.; Gopalakrishnan, R.

2008-04-01

103

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

NASA Astrophysics Data System (ADS)

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, pyrox-ene, 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 cal-culated 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 stoichiome-try (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 (~71 wt.% of bulk sample) and bulk chemical compositon 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~0 wt.% in the amporphous component. Griffithite is the preferred smectite because the position of its 02l 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.

Morris, R. V.; Ming, D. W.; Blake, D.; Vaniman, D.; Bish, D. L.; Chipera, S.; Downs, R.; Morrison, S.; Gellert, R.; Campbell, I.; Treiman, A. H.; Achilles, C.; Bristow, T.; Crisp, J. A.; McAdam, A.; Archer, P. D.; Sutter, B.; Rampe, E. B.; Team, M.

2013-12-01

104

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

SciTech Connect

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.

Borodi, G. [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania)] [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania); Pascuta, P.; Dan, V.; Pop, V. [Technical University, 28 Memorandumului, 400114 Cluj-Napoca (Romania)] [Technical University, 28 Memorandumului, 400114 Cluj-Napoca (Romania); Stefan, R. [Agricultural Science and Veterinary Medicine University, 3-5 Calea Manastur, 400372 Cluj-Napoca (Romania)] [Agricultural Science and Veterinary Medicine University, 3-5 Calea Manastur, 400372 Cluj-Napoca (Romania); Radulescu, D. [University of Medicine and Pharmacy Iuliu Hatieganu, 8 Victor Babes, 400012 Cluj-Napoca (Romania)] [University of Medicine and Pharmacy Iuliu Hatieganu, 8 Victor Babes, 400012 Cluj-Napoca (Romania)

2013-11-13

105

[Research on reducing mold flux's radiative heat transfer based on FTIR and XRD].  

PubMed

The mold fluxes samples containing transition metal oxides TiO2 were designed based on the composition of commercial mold fluxes in continuous casting of steel, and the relation between radiative heat transfer and the content of TiO2 was obtained through FTIR spectrum analysis and XRD analysis. The result of FTIR analysis indicates that TiO2 has a great negative effect on infrared transmittance of flux samples in the wavelength range of 1-6 microm. The result of XRD analysis indicates that crystallization of cuspidine was restrained with addition of TiO2, and CaTiO3 and other phases were found in the samples. The decrease in cuspidine phase is beneficial to strand lubrication in the mold. Radiation heat flux from the strand to the mold was calculated using a radiative heat transfer model concluded in previous study. Addition of TiO2 was found to result in a remarkable decrease in radiation heat flux for both glassy and crystalline samples, and the heat flux tended to decrease with increasing TiO2, with the maximal decrease reaching 30%. As a result of great refraction and scatter at surface and grain boundaries of samples, the negative effect of crystalline samples was much larger than that of the glassy ones. PMID:19445198

Diao, Jiang; Xie, Bing

2009-02-01

106

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

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

107

XRD characterisation of composite Ni-based coatings prepared by electrodeposition  

NASA Astrophysics Data System (ADS)

The present work is aimed at XRD investigation of structural parameters that influence the functional properties of Ni-W/Al2O3 electrodeposit coatings. The relationship between electrodeposition parameters and structural properties of the coatings deposited on steel substrates has been determined. XRD investigations were performed on a Bruker D8 Discover diffractometer equipped with a position-sensitive linear detector. The modified sin2? X-ray diffraction method was used to determine the macroscopic residual stresses of deposits. The crystallite size and lattice strain of the coatings were evaluated by analysis of X-ray diffraction patterns (Rietveld analysis). The crystallographic texture was analysed using the orientation distribution function (ODF) calculated from the incomplete pole figures. It was shown that the structural properties of the deposits were strongly correlated with chemical composition. X-ray diffraction patterns of all Ni-W coatings exhibit mainly the fcc phase structure of the Ni-W solid solution with a lattice parameter intermediate between those of Ni and W, which rises when the tungsten content increases. At the same time the crystallite dimension (the size of the coherent domains) was gradually reduced. It was found that Ni-W coatings containing about 40 wt.% W revealed the tensile residual stresses (2300-1200 MPa), depending on deposition conditions.

Tarkowski, L.; Indyka, P.; Be?towska-Lehman, E.

2012-08-01

108

Upgrades to the XRD1 beamline optics and endstation at the LNLS  

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

109

Influence of microstructure and interfacial strain on the magnetic properties of epitaxial Mn3O4/La0.7Sr0.3MnO3 layered-composite thin films  

NASA Astrophysics Data System (ADS)

Epitaxial Mn3O4/La0.7Sr0.3MnO3 (Mn3O4/LSMO) bilayer thin films were grown on lattice-matched single crystal substrates of SrTiO3 (STO) (100) and MgO (100), with Mn3O4 as the top layer, using a pulsed laser deposition technique. X-ray diffraction (XRD) patterns revealed the single crystalline nature and epitaxial relationship between the layers. A detailed analysis of strains using XRD asymmetric/symmetric scans indicated an increasing in-plane compressive strain in the LSMO layer with increasing thicknesses of the Mn3O4 layer, resulting in a tetragonal distortion of the LSMO lattice in the Mn3O4/LSMO films in comparison to the tensile strains in LSMO single-layer films grown on both STO and MgO substrates. Cross-sectional high resolution transmission electron microscope (HRTEM) images showed atomically sharp interfaces in all films. However, as opposed to a flat interface between LSMO and STO, the Mn3O4 and LSMO interface was undulating and irregular in the bilayer films. Magnetic measurements revealed that relative to LSMO, the presence of Mn3O4 in Mn3O4/LSMO reduced the saturation magnetization at T > 50 K (the ferrimagnetic ordering temperature of Mn3O4) but enhanced it at T < 50 K. The decrease of the saturation magnetization in Mn3O4/LSMO for T > 50 K was associated with the appearance and increase of the compressive strain with the increase in Mn3O4 thickness. These observations point to the importance of a ferromagnetic-ferrimagnetic interfacial coupling between the LSMO and Mn3O4 layers in enhancing the surface magnetism of LSMO in the Mn3O4/LSMO bilayers. Our study provides useful information regarding the development of manganite composite thin films with improved magnetic properties for a wide range of technological applications, such as in spintronics and sensor devices.

Mukherjee, Devajyoti; Bingham, Nicholas; Hordagoda, Mahesh; Phan, Manh-Huong; Srikanth, Hariharan; Witanachchi, Sarath; Mukherjee, Pritish

2012-10-01

110

Powder XRD and dielectric studies of gel grown calcium pyrophosphate crystals  

NASA Astrophysics Data System (ADS)

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.

Parekh, Bharat; Parikh, Ketan; Joshi, Mihir

2013-06-01

111

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

SciTech Connect

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.

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

2007-03-21

112

Development Of Magnetic Fe-C Nanocomposites Obtained Via The Laser Pyrolysis: Structural And Disaggregation Properties  

SciTech Connect

Fe-C) nanoparticles have been successfully synthesized using the laser pyrolysis method and variable nozzle geometries. At large nozzle diameters, XRD and SAED analysis clearly identified distinct {alpha}-Fe and Fe{sub 3}C phases. TEM and HRTEM indicated that these Fe-based nanoparticles have an average grain size of 3.5-10.2 nm. Temperature dependent Moessbauer spectra further confirm their distinct nanophases. By using a multi-step reduction procedure, Fe-C powders can be disaggregated into stable, water soluble nanoparticles.

Morjan, Ion; Alexandrescu, R.; Dumitrache, F.; Fleaca, C.; Birjega, R.; Soare, I.; Luculescu, C.-R. [National Institute for Lasers, Plasma and Radiation Physics, 111 Atomistilor, MG-36, 077125 Bucharest (Romania); Prodan, V. [Ovidius University of Constanta, 124 Mamaia, Constanta (Romania); Kuncser, V.; Filoti, G. [National Institute of Materials Physics, 105 bis Atomistilor, MG-07, 077125 Bucharest (Romania); Xu, H.; Wang, D. [Max Planck Institute of Colloids and Interfaces, Dept. of Interfaces, D-14424 Potsdam (Germany)

2010-10-06

113

Development Of Magnetic FeatC Nanocomposites Obtained Via The Laser Pyrolysis: Structural And Disaggregation Properties  

NASA Astrophysics Data System (ADS)

Fe@C) nanoparticles have been successfully synthesized using the laser pyrolysis method and variable nozzle geometries. At large nozzle diameters, XRD and SAED analysis clearly identified distinct ?-Fe and Fe3C phases. TEM and HRTEM indicated that these Fe-based nanoparticles have an average grain size of 3.5-10.2 nm. Temperature dependent Mössbauer spectra further confirm their distinct nanophases. By using a multi-step reduction procedure, Fe@C powders can be disaggregated into stable, water soluble nanoparticles.

Morjan, Ion; Alexandrescu, R.; Dumitrache, F.; Fleaca, C.; Birjega, R.; Soare, I.; Luculescu, C.-R.; Prodan, V.; Kuncser, V.; Filoti, G.; Xu, H.; Wang, D.

2010-10-01

114

Structural and Magnetic Properties of Codoped ZnO based Diluted Magnetic Semiconductors  

Microsoft Academic Search

Zn1-xCoxO (x = 0.01, 0.02, 0.05, 0.10 and 0.20) diluted magnetic semiconductors are prepared by the sol-gel method. The structural and magnetic properties of the samples are studied using x-ray diffraction (XRD), extended x-ray absorption fine structure (EXAFS) and superconducting quantum interference device (SQUID). The XRD patterns does not show any signal of precipitates that are different from wurtzite type

Bin-Bin Li; Hong-Lie Shen; Rong Zhang; Xiang-Qiang Xiu; Zhi Xie

2007-01-01

115

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

SciTech Connect

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.

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

2009-11-18

116

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

SciTech Connect

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)

Ferreira, Eduardo G.A.; Marumo, Julio T.; Vicente, Roberto [Nuclear and Energy Research Institute, Sao Paulo (Brazil); Gobbo, Luciano [Institute of Geosciences, University of Sao Paulo, Sao Paulo (Brazil)

2012-07-01

117

XRD monitoring of ? self-irradiation in uranium-americium mixed oxides.  

PubMed

The structural evolution under (241)Am self-irradiation of U(1-x)Am(x)O(2±?) transmutation fuels (with x ? 0.5) was studied by X-ray diffraction (XRD). Samples first underwent a preliminary heat treatment performed under a reducing atmosphere (Ar/H2(4%)) aiming to recover the previously accumulated structural defects. Over all measurements (carried out over up to a full year and for integrated doses up to 1.5 × 10(18) ?-decay events·g(-1)), only fluorite U(1-x)Am(x)O(2±?) solid solutions were observed. Within a few days after the end of the heat treatment, each of the five studied samples was slowly oxidized as a consequence of their move to air atmosphere, which is evidenced by XRD by an initial sharp decrease of the unit cell parameter. For the compounds with x ? 0.15, this oxidation occurred without any phase transitions, but for U0.6Am0.4O(2±?) and U0.5Am0.5O(2±?), this process is accompanied by a transition from a first fluorite solid solution to a second oxidized one, as the latter is thermodynamically stable in ambient conditions. In the meantime and after the oxidation process, (241)Am ? self-irradiation caused a structural swelling up to ?0.8 vol %, independently of the sample composition. The kinetic constants of swelling were also determined by regression of experimental data and are, as expected, dependent on x and thus on the dose rate. The normalization of these kinetic constants by sample ?-activity, however, leads to very close swelling rates among the samples. Finally, evolutions of microstrain and crystallite size were also monitored, but for the considered dose rates and cumulated doses, ? self-irradiation was found, within the limits of the diffractometer used, to have almost no impact on these characteristics. Microstrain was found to be influenced instead by the americium content in the materials (i.e., by the impurities associated with americium starting material and the increase of cationic charge heterogeneity with increasing americium content). PMID:24266774

Horlait, Denis; Lebreton, Florent; Roussel, Pascal; Delahaye, Thibaud

2013-12-16

118

Spectroscopic and XRD characterisation of zeolite catalysts active for the oxidative methylation of benzene with methane.  

PubMed

The benzene methylation with methane over zeolite catalysts was previously shown in our laboratory to require the presence of oxygen. Thus, a two-step mechanism involving the intermediate formation of methanol by partial oxidation of methane followed by the methylation of benzene with methanol in the second step, was postulated. This paper now reports the results of the characterisation of the zeolite catalysts used for the oxidative benzene methylation reaction in order to provide some information about their composition, structure, properties and their behaviour before and after the reaction. The catalysts were characterised by X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray fluorescence (XRF), FT-IR and solid state NMR. XRD results indicate that the crystalline structures of all the ZSM-5 and H-beta catalysts remained unchanged after batch reaction of benzene with methane over the catalysts in agreement with the observation that the catalysts recovered from the reactor could be reused without loss of activity. Elemental analyses and FT-IR data show that as the level of metal ion exchange increases, the Brönsted acid concentration decreases but this metal ion exchange does not totally remove Brönsted acidity. FT-IR results further show that only a small amount of acid sites is actually necessary for a catalyst to be active since used catalysts containing highly reduced Brönsted acidity are found to be reusable without any loss of their activity. 29Si and 27Al magic angle spinning (MAS) NMR together with FT-IR spectra also show that all the active zeolites catalysts contain some extra-framework octahedral aluminium in addition to the normal tetrahedral framework aluminium. The presence of this extra-lattice aluminium does not, however, have any adverse effect on the crystallinity of the catalysts both before and after oxidative benzene methylation reaction. There appears also to be no significant dealumination of the zeolite catalysts during reaction since their catalytic performance was retained after use. PMID:15036089

Adebajo, Moses O; Long, Mervyn A; Frost, Ray L

2004-03-01

119

Data from the Mars Science Laboratory CheMin XRD/XRF Instrument  

NASA Technical Reports Server (NTRS)

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.

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

120

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

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

121

Correlative Characterization of Li-S Batteries Using In situ TXM and XRD  

NASA Astrophysics Data System (ADS)

Sulfur is an attractive Li-ion battery cathode material candidate because of its high specific energy (2600 Wh/kg); however, it is well known that Li-S batteries suffer from capacity loss or fading. It is generally accepted that this is due to the loss of active material and the formation of nonconducting Li2S as a thin film coating the electrode. Both phenomena stem from the dissolution of active sulfur particles in the non-aqueous electrolyte as soluble long chain polysulfides form during the early stages of cell discharge. Using in situ, high resolution transmission X-ray microscopy (TXM) at SSRL beam line 6-2 and in situ X-ray diffraction (XRD) at beam line 11-3, we have explored initial discharge and charge cycle of Li-S batteries in real time. By combining these complementary methods, we can characterize the morphological changes of the active material as well as changes in crystallinity and crystal structure. We can then correlate these changes and the electrochemistry to better understand the reduction of elemental sulfur and various adaptations employed to retain battery capacity over many cycles.

Nelson, Johanna; Misra, Sumohan; Yang, Yuan; Jackson, Ariel; Cui, Yi; Andrews, Joy; Toney, Michael

2011-11-01

122

X-Ray Powder Diffraction (XRD) Studies on Kenaf Dust Filled Chitosan Bio-composites  

NASA Astrophysics Data System (ADS)

Kenaf dust filled chitosan bio-composites with various compositions of kenaf dust (i.e. 7%, 14%, 21% and 28%) were prepared using solution casting technique. The degree of relative crystallinity of the bio-composites was determined using XRD method. Two distinguishable crystalline peaks were observed in the 2? range of 5 to 40 ° which indexed as 020 and 110 respectively. It was noted that the maximum peak of intensity at 020 crystalline peak increased with addition of kenaf dust as well as the second maximum peak of intensity at 110. Consequently, Fourier Transform Infrared (FTIR) analysis was done to investigate the interaction between kenaf dust and chitosan matrix. From FTIR analysis, corresponding peak of chitosan was detected at wavelength of 3233.2 cm-1 indicated that there exist intermolecular interactions between kenaf dust and chitosan matrix. These results highlighted that there are greater intermolecular forces formed in chitosan with addition of kenaf dust. Intermolecular forces were attributed to the formation of inter and intra hydrogen bonding between chitosan polymer and cellulosic kenaf dust filler.

Julkapli, N. Muhd; Md Akil, H.

2008-03-01

123

[X-ray powder diffraction (XRD) in the study of biomaterials used in dentistry. 3].  

PubMed

This study considers X-ray power diffraction (XRD) applied to the study of mineral-based biomaterials used in odontostomatology. By means of this method the following materials were analysed: reabsorbable Dac Blu, non reabsorbable Dac Blu, non reabsorbable atomized Dac Blu, non reabsorbable fine Dac Blu, reabsorbable Biocoral 450, Calcitite 2040-12, Orthogel, Apagen, BTF 65, Calcitite 4060-2, Osprogel, Bio-oss, Biostite, Osprovit, Merck Hydroxyapatite. These analysis allow the identification of the crystalline phases, the study of the crystallinity and the crystal chemistry of the samples prepared as powder mixtures. This method permits the determination of the physical chemical and crystalline characteristics of these mineral based biomaterials formed by powders or transformable in powders. All of this information is indispensable for the evaluation of the functional biocompatibility of a biomaterial when its reaction in a biological environment is already known. This method has a great number of advantages against the traditional methods, marking with solid phases, it does not destroy the sample, it does not modify the physical or chemical characteristics and gives more information. PMID:7783708

Valdré, G; Mongiorgi, R; Monti, S; Corvo, G; Itro, A; Paroli, R; Cozzolino, A

1995-01-01

124

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

NASA Astrophysics Data System (ADS)

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.

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

2008-07-01

125

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

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

126

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

SciTech Connect

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)

Stefanovsky, S.V. [SIA Radon, 7th Rostovskii lane 2/14, Moscow 119121 (Russian Federation) [SIA Radon, 7th Rostovskii lane 2/14, Moscow 119121 (Russian Federation); Institute of Physical Chemistry and Electrochemistry RAS, Leninskii av. 31, Moscow 119991 (Russian Federation); Nikonov, B.S.; Omelianenko, B.I. [Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry RAS, Staromonetniy lane 35, Moscow 100117 (Russian Federation)] [Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry RAS, Staromonetniy lane 35, Moscow 100117 (Russian Federation); Choi, A.; Marra, J.C. [Savannah River National Laboratory, Building 773A, Aiken 29808 (United States)] [Savannah River National Laboratory, Building 773A, Aiken 29808 (United States)

2013-07-01

127

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

SciTech Connect

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.

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

2007-05-24

128

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

NASA Astrophysics Data System (ADS)

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.

Jablonska, Magdalena Barbara

2014-04-01

129

XRD and XAS structural study of CuAlO2 under high pressure  

NASA Astrophysics Data System (ADS)

We present the results of x-ray diffraction and x-ray absorption spectroscopy experiments in CuAlO2 under high pressure. We discuss the polarization dependence of the x-ray absorption near-edge structure at the Cu K-edge. XRD under high pressure evidences anisotropic compression, the a-axis being more compressible than the c-axis. EXAFS yields the copper-oxygen bond length, from which the only internal parameter of the delafossite structure is deduced. The combination of anisotropic compression and the internal parameter decrease results in a regularization of the AlO6 octahedra. The anisotropic compression is related to the chemical trends observed in the lattice parameters when Al is substituted by other trivalent cations. Both experiments evidence the existence of an irreversible phase transition that clearly manifests at 35 ± 2 GPa. The structure of the high-pressure polymorph could not be determined, but it implies a change of the Cu environment, which remains anisotropic. Precursor effects are observed from the lowest pressures, which are possibly related to crystal breaking at a submicroscopic scale with partial reorientation of the crystallites.

Pellicer-Porres, J.; Segura, A.; Ferrer-Roca, Ch; Polian, A.; Munsch, P.; Kim, D.

2013-03-01

130

XRD and XAS structural study of CuAlO2 under high pressure.  

PubMed

We present the results of x-ray diffraction and x-ray absorption spectroscopy experiments in CuAlO(2) under high pressure. We discuss the polarization dependence of the x-ray absorption near-edge structure at the Cu K-edge. XRD under high pressure evidences anisotropic compression, the a-axis being more compressible than the c-axis. EXAFS yields the copper-oxygen bond length, from which the only internal parameter of the delafossite structure is deduced. The combination of anisotropic compression and the internal parameter decrease results in a regularization of the AlO(6) octahedra. The anisotropic compression is related to the chemical trends observed in the lattice parameters when Al is substituted by other trivalent cations. Both experiments evidence the existence of an irreversible phase transition that clearly manifests at 35 ± 2 GPa. The structure of the high-pressure polymorph could not be determined, but it implies a change of the Cu environment, which remains anisotropic. Precursor effects are observed from the lowest pressures, which are possibly related to crystal breaking at a submicroscopic scale with partial reorientation of the crystallites. PMID:23423689

Pellicer-Porres, J; Segura, A; Ferrer-Roca, Ch; Polian, A; Munsch, P; Kim, D

2013-03-20

131

RBS-channeling, ERDA and XRD study of lithium tantalate modified by annealed proton exchange (APE)  

NASA Astrophysics Data System (ADS)

Lithium tantalate (LT) single crystals are very promising substrates for constructing highly sophisticated photonics devices. The used procedure for fabricating optical waveguides in them was annealed proton exchange (APE). Here we have used Rutherford backscattering spectrometry (RBS) - channeling analysis, X-ray diffraction (XRD) and elastic recoil detection analysis (ERDA) to study changes in the surface of the LT wafers caused by the APE treatment and to determine the concentration depth profiles of hydrogen atoms. The measurements were taken for both virgin (untreated) and APE:LT samples fabricated using various experimental conditions. We have found that the incorporation of hydrogen during the first step, i.e. the PE procedure (proton exchange), leads to modifications of the structure of the LT single crystal, which gradually relaxed towards the structure of the original LT during the post-proton-exchange annealing (A). This study also revealed a substantial dependence of sample behaviour on the crystallographic orientation of the pertinent substrate wafers (commonly used X-(<1 1 -2 0>) and Z-(<0 0 0 1>) cuts).

Macková, Anna; Salavcová, L.; Špirková, Jarmila; Groetzschel, R.; Eichhorn, F.

2006-08-01

132

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

NASA Astrophysics Data System (ADS)

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.

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

2013-11-01

133

Preparation and characterization of magnetic nanoparticles with chitosan coating  

Microsoft Academic Search

Magnetic chitosan nanoparticles were prepared by the suspension cross-linking technique for use in the application of magnetic carrier technology. The Fe3O4 magnetic nanoparticles were synthesized by co-precipitation of FeCl2 and FeCl3 solution in base medium for using in the preparation of the magnetic chitosan. The morphological and magnetic properties of the magnetic nanoparticles were characterized by different techniques (TEM, XRD,

Doan Thi Kim Dung; Tran Hoang Hai; Le Hong Phuc; Bui Duc Long; Le Khanh Vinh; Phan Nha Truc

2009-01-01

134

Crystallinity of cellulose, as determined by CP\\/MAS NMR and XRD methods  

Microsoft Academic Search

The crystallinity of six cellulose samples with different origin and treatment was determined using x-ray diffraction (XDR) and nuclear magnetic resonance with cross polarization and magic angle sample spinning (CP\\/MAS NMR) methods. The numerical results for crystallinity obtained by using curve fitting methods in both cases correlated very well. It was concluded that the values for the crystallinity can be

R. Teeäär; R. Serimaa; T. Paakkarl

1987-01-01

135

Quantitative shock stage assessment in olivine and pyroxene bearing meteorites via in situ micro-XRD  

NASA Astrophysics Data System (ADS)

Shock metamorphism is observed in most meteorites and impact structures [1]. Qualitative petrographic observations underpin a shock classification system [1-3] based on the deformation features in common silicates and on textural relations such as the development of maskelynite from feldspars, mobility of sulphides and metal in veins and local Fe-reduction in silicates. Shock deformation of minerals produces streaks (mosaicity) rather than discrete spots in 2D X-ray diffraction patterns, representing the progressive disruption of the crystal lattice into a mosaic of rotated domains [4,5]. Here we use in situ micro-XRD [5,6] to measure the mosaicity of olivine and pyroxene in ordinary chondrites of increasing shock stages S1 to S5 and then apply the method to achondrites with qualitatively low to high shock. X-ray diffraction data were collected in situ on polished thin sections and slab cut surfaces using a Bruker D8 Discover micro X-ray diffractometer [5], operated using CuK? radiation generated at 40 kV and 40 mA with a beam diameter of 500 ?m. Diffracted X-rays were recorded with a 2D detector, giving images with information in both the 2-theta and chi dimensions, in which each lattice plane (hkl) will have a diffraction spot or streak lying along an arc in chi of radius 2-theta (hkl). Individual reflections can be indexed and then integrated as a function of chi angle, allowing examination of the peak shape and quantitative analysis of the mosaic peak FWHM along chi. We find that both forsterite and enstatite exhibit greater mosaicity in chi with increasing shock stage: Forsterite chi ranges from <1° for S1 to >6° for S5. Enstatite chi values from the same meteorites show a more subdued growth of streak length with shock state, from ~1° to ~4°. A slab of the olivine shergottite DaG 476 exhibits forsterite mosaicity of 6.9°+/-1.1°, indicating that it has experienced shock stage S5, with shock pressures 30-45 GPa [1,4], consistent with the 40-45 GPa shock pressure estimated for DaG 476 by plagioclase refractive index [7]. These observations show that shock classification -and potentially shock pressure calibration- can be done using in situ XRD mineral data. [1] Stoffler, D. et al., (1991) GCA 55, 3845-3867. [2] Scott, E.R.D. et al., (1992) GCA 56, 4281-4293. [3] Rubin, A.E. et al., (1997) GCA 61, 847-858. [4] Horz, F. and Quiade, W.I. (1973) The Moon 6, 45-86. [5] Flemming, R.L. (2007) Can. Jour. Earth Sci. 44, 1333-1346. [6] Izawa, M.R.M. et al., (2009) LPSC XV. [7] Fritz, J. et al., (2005) MAPS 40, 1393-1411.

McCausland, P. J.; Flemming, R. L.; Izawa, M. R.

2010-12-01

136

Structural, static and dynamic magnetic properties of dextran coated ?-Fe2O3 nanoparticles studied by 57Fe NMR, Mössbauer, TEM and magnetization measurements  

NASA Astrophysics Data System (ADS)

The structural and magnetic properties and spin dynamics of dextran coated and uncoated ?-Fe2O3 (maghemite) nanoparticles have been investigated using high resolution transmission electron microscopy (HRTEM), 57Fe nuclear magnetic resonance (NMR), Mössbauer spectroscopy and dc magnetization measurements. The HRTEM observations indicated a well-crystallized system of ellipsoid-shaped nanoparticles, with an average size of 10 nm. The combined Mössbauer and magnetic study suggested the existence of significant interparticle interactions not only in the uncoated but also in the dextran coated nanoparticle assemblies. The zero-field NMR spectra of the nanoparticles at low temperatures are very similar to those of the bulk material, indicating the same hyperfine field values at saturation in accord with the performed Mössbauer measurements. The T2 NMR spin-spin relaxation time of the nanoparticles has also been measured as a function of temperature and found to be two orders of magnitude shorter than that of the bulk material. It is shown that the thermal fluctuations in the longitudinal magnetization of the nanoparticles in the low temperature limit may account for the shortening and the temperature dependence of the T2 relaxation time. Thus, the low temperature NMR results are in accord with the mechanism of collective magnetic excitations, due to the precession of the magnetization around the easy direction of the magnetization at an energy minimum, a mechanism originally proposed to interpret Mössbauer experiments in magnetic nanoparticles. The effect of the surface spins on the NMR relaxation mechanisms is also discussed.

Fardis, M.; Douvalis, A. P.; Tsitrouli, D.; Rabias, I.; Stamopoulos, D.; Kehagias, Th; Karakosta, E.; Diamantopoulos, G.; Bakas, T.; Papavassiliou, G.

2012-04-01

137

Quantitative analysis of interfacial strain in InAs/GaSb superlattices by aberration-corrected HRTEM and HAADF-STEM.  

PubMed

The strain distribution across interfaces in InAs/GaSb superlattices grown on (100)-GaSb substrates is investigated by aberration corrected transmission electron microscopy. Atomic resolution images of interfaces were obtained by conventional high resolution transmission electron microscopy (HRTEM), using the negative spherical-aberration imaging mode, and by scanning transmission electron microscopy (STEM), using the high-angle annular dark-field (HAADF) imaging mode. The local atomic displacements across interfaces were determined from these images using the peak pair algorithm, from which strain maps were calculated with respect to a reference lattice extracted from the GaSb substrate region. Both techniques yield consistent results, which reveal that the InAs-on-GaSb interface is nearly strain balanced, whereas the GaSb-on-InAs interface is in tensile strain, indicating that the prevalent bond type at this interface is Ga-As. In addition, the GaSb layers in the superlattice are compressively strained indicating the incorporation of In into these layers. Further analysis of the HAADF-STEM images indicates an estimated 4% In content in the GaSb layers and that the GaSb-on-InAs interface contributes to about 27% of the overall superlattice strain. The strain measurements in the InAs layers are in good agreement with the theoretical values determined from elastic constants. Furthermore, the overall superlattice strain determined from this analysis is also in good agreement with the measurements determined by high-resolution X-ray diffraction. PMID:23298538

Mahalingam, Krishnamurthy; Haugan, Heather J; Brown, Gail J; Eyink, Kurt G

2013-04-01

138

New magnetic nanoparticles for biotechnology.  

PubMed

Paramagnetic carriers, which are linked to antibodies enable highly specific biological cell separations. With the colloidal synthesis of superparamagnetic Co and FeCo nanocrystals with superior magnetic moments the question about their potential to replace magnetite as the magnetically responsive component of magnetic beads is addressed. Starting from a magnetic analysis of the corresponding magnetophoretic mobility of Co and FeCo based alloys their synthesis and resulting microstructural and magnetic properties as function of the underlying particle size distribution are discussed in detail. The stability of the oleic acid ligand of Co nanocrystals has been investigated. The oxidation kinetics were quantified using magnetic measurements. As a result, this ligand system provides sufficient protection against oxidation. Furthermore, the kinetics of the synthesis of Fe(50)Co(50) nanoparticles has been monitored employing Fourier transform infra red (FT-IR) spectroscopy and is modeled using a consecutive decomposition and growth model. This model predicts the experimentally realized FeCo nanoparticle composition as a function of the particle size fairly well. High-resolution transmission electron microscopy (HRTEM) was performed to uncover the resulting microstructure and composition on a nanometer scale. PMID:15288940

Hütten, Andreas; Sudfeld, Daniela; Ennen, Inga; Reiss, Günter; Hachmann, Wiebke; Heinzmann, Ulrich; Wojczykowski, Klaus; Jutzi, Peter; Saikaly, Wahib; Thomas, Gareth

2004-08-26

139

Corrosion of Depleted Uranium in an Arid Environment: Soil-Geomorphology, SEM\\/EDS, XRD, and Electron Microprobe Analyses  

Microsoft Academic Search

Corrosion of anthropogenic uranium in natural environments is not well understood, but is important for determining potential health risks and mobility in the environment. A site in the southwestern United States contains depleted uranium that has been weathering for approximately 22 years. Soil-geomorphic, SEM\\/EDS, XRD, and electron microprobe analyses were conducted to determine the processes controlling the uranium corrosion. Schoepite

BRENDA J. BUCK; AMY L. BROCK; WILLIAM H. JOHNSON; APRIL L. ULERY

2004-01-01

140

Combined Raman-LIBS, Moessbauer and XRD In-Situ Mineral Analysis of Evaporite Minerals at Rio Tinto (Spain)  

NASA Astrophysics Data System (ADS)

In this study a combination of Raman, LIBS, Mössbauer and XRD portable instruments has been used to undertake a common in-situ analysis of sulphate minerals at Rio Tinto area within the CAREX Field Procedure Inter-comparison Exercise 2009.

Rull, F.; Klingelhöfer, G.; Sarrazin, P.; Medina, J.; Fleischer, I.; Blake, D.; Martin Ramos, J. D.

2010-04-01

141

Structure and magnetic properties of Nb-doped FeZrB soft magnetic alloys  

Microsoft Academic Search

Structure and magnetic properties of Nb-doped (FeZrB)100?xNbx alloy 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. With increasing Nb, the glass transition temperature and the onset crystallization temperature are increased, indicating increased stability of the amorphous structure. For x=1, the saturation

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

2011-01-01

142

Structure and magnetic properties of Nb-doped FeZrB soft magnetic alloys  

Microsoft Academic Search

Structure and magnetic properties of Nb-doped (FeZrB)100-xNbx alloy 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. With increasing Nb, the glass transition temperature and the onset crystallization temperature are increased, indicating increased stability of the amorphous structure. For x=1, the saturation

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

2011-01-01

143

Preparation and XRD analyses of Na-doped ZnO nanorod arrays based on experiment and theory  

NASA Astrophysics Data System (ADS)

ZnO nanorod arrays (NRAs) with different Na contents were prepared by thermal evaporation. Sodium pyrophosphate was adopted as the Na source. The Na contents in NRAs were determined by X-ray photoelectron spectra to be 0, 6.1, and 9.4 at.%. X-ray diffraction (XRD) analyses of Na-doped ZnO NRAs were performed in experiment and by first-principle calculation with the assumption of Na substitutions. A couple of typical changes were found in XRD patterns of Na-doped ZnO. The simulation results well agreed with the experimental data, which revealed that Na mainly located at the substitutional sites in Na-doped ZnO NRAs.

Yang, X. P.; Lu, J. G.; Zhang, H. H.; Chen, Y.; Kan, B. T.; Zhang, J.; Huang, J.; Lu, B.; Zhang, Y. Z.; Ye, Z. Z.

2012-03-01

144

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

USGS Publications Warehouse

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.

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

2006-01-01

145

Magnetic nanocomposite for high Q embedded inductor  

Microsoft Academic Search

Magnetic nanophase cobalt ferrite particles were synthesized through a water-based method. The obtained nanoparticles were characterized by x-ray diffraction (XRD), transmission electronic microscopy (TEM), and superconducting quantum interference device (SQUID) magnetometer. Magnetic nanocomposite was prepared by mixing the nanoparticle with epoxy\\/anhydride matrix. The dielectric and magnetic properties of the composite were measured by LCR meter and SQUID magnetometer. The design

Hai Dong; Fuhan Liu; C. P. Wong; Qing Song; Z. John Zhang

2004-01-01

146

XRD and TEM analysis on the Fe 3Al\\/18-8 stainless steel diffusion bonded interface  

Microsoft Academic Search

Fe3Al intermetallic and 18-8 stainless steel were diffusion-bonded at 1040 °C for 60 min. The reacted phase in the Fe3Al\\/18-8 diffusion-bonded interface was determined via X-ray diffractometry (XRD) and the lattice orientation relation between constituent phases was analyzed by transmission electron microscope (TEM). The results indicated that there were Fe3Al, Ni3 Al, FeAl, ?-Fe (Al) solid solution and Fe3C in

Juan Wang; Yajiang Li; Peng Liu

2003-01-01

147

In and Al composition in nano-Cu(InAl)Se 2 thin films from XRD and transmittance spectra  

Microsoft Academic Search

Cu(InAl)Se2 (CIAS) thin films of different thicknesses were prepared by chemical bath deposition technique (CBD) onto well-cleaned substrates at different temperatures from two different chemical baths. The thickness of the deposited films has been determined by gravimetric technique. The composition of indium and aluminum constituents in the prepared CIAS films has been found from XRD and transmittance spectra. The results

B. Kavitha; M. Dhanam

2007-01-01

148

Temperature dependence of the cation distribution in nickel aluminate (NiAl 2 O 4 ) spinel: a powder XRD study  

Microsoft Academic Search

NiAl2O4 is a largely inverse spinel, which in detail shows increasing randomisation with temperature of Ni and Al between the octahedral and tetrahedral cation sites of the spinel structure. We have used powder XRD to determine this cation distribution in various samples of NiAl2O4 quenched after annealing between 700 and 1400° C. The inversion parameter (x) can be measured with

H. St. C. O'Neill; W. A. Dollase; C. R. Ross

1991-01-01

149

Size and distribution: a comparison of XRD, SAXS and SANS study of II-VI semiconductor nanocrystals.  

PubMed

The uniqueness of size dependent functional properties of II-VI semiconductor nanocrystals have led to the development of various techniques for determination of shape, size and distributions, although the accurate measurements of the particle sizes has always been a fundamental task in nanoscience and even become more crucial with the discovery of quantum confinement effect. A comparison of the well established techniques X-ray diffraction (XRD), small angle X-ray scattering (SAXS) and small angle neutron scattering (SANS) with an emphasis on size and distribution of the prepared samples are reported in order to elaborate more precise techniques for the analysis of particles sizes. Modified Scherrer formula for spherical particles has been used to calculate the particle sizes from XRD spectra. Analysis of SAXS data has been reported using Guinier model. Small angle neutron scattering measurements has been performed for ZnO nanocrystals and the scattering data obtained is simulated for polydisperse sphere. The bare ZnO, ZnS and CdS and doped with Mn2+ systems are taken within the framework of our discussion. These materials were synthesized by chemical precipitation route and found to have size distribution from 2 to 6 nm for spherical particles. Sizes determined from various techniques are in good agreement with each other however small angle scattering technique is more reliable than XRD to determine the sizes of the nanoparticles. PMID:18468128

Keshari, Ashish K; Pandey, Avinash C

2008-03-01

150

Preparation and characterization of magnetic nanoparticles with chitosan coating  

NASA Astrophysics Data System (ADS)

Magnetic chitosan nanoparticles were prepared by the suspension cross-linking technique for use in the application of magnetic carrier technology. The Fe3O4 magnetic nanoparticles were synthesized by co-precipitation of FeCl2 and FeCl3 solution in base medium for using in the preparation of the magnetic chitosan. The morphological and magnetic properties of the magnetic nanoparticles were characterized by different techniques (TEM, XRD, VSM, FTIR, etc.). The magnetic properties of chitosan - magnetic nanoparticles were analyzed by VSM, and MS around 15 emu/g.

Dung, Doan Thi Kim; Hoang Hai, Tran; Phuc, Le Hong; Long, Bui Duc; Khanh Vinh, Le; Nha Truc, Phan

2009-09-01

151

Controlled oxidation of FeCo magnetic nanoparticles to produce faceted FeCo/ferrite nanocomposites for rf heating applications  

E-print Network

for rf heating applications K. N. Collier,1,2 N. J. Jones,1 K. J. Miller,1 Y. L. Qin,1 D. E. Laughlin,1 for polydisperse FeCo magnetic nanoparticles MNPs synthesized using an induction plasma torch. X-ray diffraction the FeCo core and oxide shell. We show HRTEM images of MNP chaining and compare the rf heating of samples

Laughlin, David E.

152

Use of an Ultrasonic\\/Sonic Driller\\/Corer to Obtain Sample Powder for CHEMIN, a Combined XRD\\/XRF Instrument  

Microsoft Academic Search

An ultrasonic drill was used to produce powder for CHEMIN XRD\\/XRF analyses and was found to do an outstanding job on all materials tested. XRD patterns and particle size distributions are comparable with powders obtained from a laboratory mill.

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

2003-01-01

153

Sol–gel synthesis, structure and magnetic properties of Mn-doped ZnO diluted magnetic semiconductors  

Microsoft Academic Search

2.5, 5, 10 and 15% Mn-doped ZnO diluted magnetic semiconductors (DMSs) were prepared via an ethyl acetoacetate-aided sol–gel process. The 5% Mn-doped ZnO consists of 20–50nm spheroid-like particles and has a wurtzite phase. Existence of nanoscale ZnMnO3 clusters in this sample is confirmed by HRTEM analysis. Vegard's law calculation reveals that about 2.6% Mn atoms have been incorporated into ZnO

Yingjing Jiang; Wei Wang; Chengbin Jing; Chunyue Cao; Junhao Chu

2011-01-01

154

Sorption processes and XRD analysis of a natural zeolite exchanged with Pb(2+), Cd(2+) and Zn(2+) cations.  

PubMed

In this study the Pb(2+), Cd(2+) and Zn(2+) adsorption capacity of a natural zeolite was evaluated in batch tests at a constant pH of 5.5 by polluting this mineral with solutions containing increasing concentrations of the three cations to obtain adsorption isotherms. In addition X-ray powder diffraction (XRD) was used to investigate the changes of zeolite structure caused by the exchange with cations of different ionic radius. The zeolite adsorption capacity for the three cations was Zn>Pb>Cd. Moreover a sequential extraction procedure [H(2)O, 0.05 M Ca(NO(3))(2) and 0.02 M EDTA] was applied to zeolite samples used in the adsorption experiments to determine the chemical form of the cations bound to the sorbent. Using this approach it was shown that low concentrations of Pb(2+), Cd(2+) and Zn(2+) were present as water-soluble and exchangeable fractions (<25% of the Me adsorbed), while EDTA extracted most of the adsorbed cations from the zeolite (>27% of the Me adsorbed). The XRD pattern of zeolite, analysed according to the Rietveld method, showed that the main mineralogical phase involved in the adsorption process was clinoptilolite. Besides structure information showed that the incorporation of Pb(2+), Cd(2+) and Zn(2+), into the zeolite frameworks changed slightly but appreciably the lattice parameters. XRD analysis also showed the occurrence of some isomorphic substitution phenomena where the Al(3+) ions of the clinoptilolite framework were replaced by exchanged Pb(2+) cations in the course of the ion exchange reaction. This mechanism was instead less evident in the patterns of the samples doped with Cd(2+) and Zn(2+) cations. PMID:18242839

Castaldi, Paola; Santona, Laura; Enzo, Stefano; Melis, Pietro

2008-08-15

155

XRD study on the electrochemical hydriding\\/dehydriding behavior of the La–Mg–Ni–Cotype hydrogen storage alloys  

Microsoft Academic Search

Electrochemical hydriding\\/dehydriding behavior of the La–Mg–Ni-based alloy La0.7Mg0.3(Ni0.85Co0.15)3.5 consisting of a (La,Mg)Ni3 phase with the PuNi3-type rhombohedral structure and a LaNi5 phase with the CaCu5-type hexagonal structure was systematically investigated by means of X-ray diffraction (XRD) analyses. The results indicate that the PuNi3-type rhombohedral structure and the CaCu5-type hexagonal structure of the alloy are still preserved during hydriding\\/dehydriding process. For

Yongfeng Liu; Hongge Pan; Mingxia Gao; Yongquan Lei; Qidong Wang

2005-01-01

156

Structural study of an amorphous CuTi alloy produced by mechanical alloying using XRD, EXAFS and RMC simulations  

NASA Astrophysics Data System (ADS)

The structure of an amorphous Cu 64Ti 36 alloy produced by mechanical alloying was studied by X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) spectroscopy techniques and modeled through reverse Monte Carlo simulations using the total structure factor S(K) and the EXAFS ?(k) oscillations on Cu K edge as input data. From the simulations the partial pair distribution functions g(r) and the bond-angle distribution functions ?(cos?) were determined and, from these functions, average coordination numbers and average interatomic distances for the first neighbors were calculated. We also obtained information about the three-dimensional structures present in the alloy.

Machado, K. D.; Maciel, G. A.; Sanchez, D. F.; de Lima, J. C.; Jóvári, P.

2010-09-01

157

Astrobiological Significance of Definitive Mineralogical Analysis of Martian Surface Samples Using the CheMin XRD/XRF Instrument  

NASA Technical Reports Server (NTRS)

The search for evidence of habitability, or of extant or extinct life on Mars, will initially be a search for evidence of past or present conditions supportive of life. The three key requirements for the emergence of life are thought to be liquid water; a suitable energy source; and chemical building blocks. CheMin is a miniaturized XRD/XRF (X-Ray diffraction / X-ray fluorescence) instrument which has been developed for definitive mineralogic analysis of soils and rocks on the Martian surface. The CheMin instrument can provide information that is highly relevant to each of these habitability requirements as summarized below.

Feldman, S. M.; Blake, D. F.; Sarrazin, P.; Bish, D. L.; Chipera, S. J.; Vaniman, D. T.; Collins, S.

2004-01-01

158

Magnetic properties of new glassy Fe Au(Cu) B alloys  

NASA Astrophysics Data System (ADS)

The evolution of the microstructure and soft magnetic properties of Fe 76Au 4-xCu xB 20 and Fe 87Au 2-xCu xB 11 melt spun ribbons prepared at different cooling rates were investigated. The samples are stable above room temperature and display saturation induction up to 1.79 T and magnetic permeabilities of over 2×10 4 at 300 K. The structure is not fully amorphous, as proved by DSC and HRTEM investigations, but consists of very small grains of about 10 nm, randomly dispersed in the amorphous residual matrix. The grains composition strongly depends on the B content.

Lupu, Nicoleta; Inoue, Akihisa

2005-04-01

159

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

PubMed

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, (1)H NMR, (13)C 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, (1)H NMR, (13)C 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. PMID:24820326

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

2014-10-15

160

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

161

Thermoluminescence (TL) properties and x-ray diffraction (XRD) analysis of high purity CaSO4:Dy TL material  

NASA Astrophysics Data System (ADS)

This paper presents the characterization and TL properties of dysprosium (Dy) doped calcium sulfate (CaSO4) 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 CaSO4 with average crystallite size of 74 nm with orthorhombic crystal system. The TL behavior of produced CaSO4:Dy was studied using a TLD reader after exposure to gamma ray by Co60 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.

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

2014-09-01

162

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

SciTech Connect

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.

L MacLean; S Beauchemin; P Rasmussen

2011-12-31

163

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

NASA Astrophysics Data System (ADS)

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 fossilbearing 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.

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

1998-12-01

164

Effect of annealing temperature on the structural, photoluminescence and magnetic properties of sol-gel derived Magnetoplumbite-type (M-type) hexagonal strontium ferrite  

NASA Astrophysics Data System (ADS)

Magnetoplumbite-type (M-type) hexagonal strontium ferrite particles were synthesized via sol-gel technique employing ethylene glycol as the gel precursor at two different calcination temperatures (800 and 1000 °C). Structural properties were systematically investigated via X-ray diffraction (XRD), field emission scanning electron microscopy, high resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), photoluminescence spectrophotometry and superconducting quantum interference device magnetometer. XRD results showed that the sample synthesized at 1000 °C was of single-phase with a space group of P6 3/mmc and lattice cell parameter values of a=5.882 Å and c=23.048 Å. EDS confirmed the composition of strontium ferrite calcined at 1000 °C being mainly of M-type SrFe 12O 19 with HRTEM micrographs confirming the ferrites exhibiting M-type long range ordering along the c-axis of the crystal structure. The photoluminescence (PL) property of strontium ferrite was examined at excitation wavelengths of 260 and 270 nm with significant PL emission peaks centered at 350 nm being detected. Strontium ferrite annealed at higher temperature (1000 °C) was found to have grown into larger particle size, having higher content of oxygen vacancies and exhibited 83-85% more intense PL. Both the as-prepared strontium ferrites exhibited significant oxygen vacancies defect structures, which were verified via TGA. Higher calcination temperature turned strontium ferrite into a softer ferrite.

Teh, Geok Bee; Wong, Yat Choy; Tilley, Richard D.

2011-09-01

165

Magnetic measurements on ??CS{sub 2}U{sub 4}O{sub 12}  

SciTech Connect

Magnetic and XRD measurements on ??CS{sub 2}U{sub 4}O{sub 12} having uranium in mixed valent states of U (V) and U (VI) have been made. The study reveals that the compound undergoes an antiferromagnetic transition below 25K and an anomalous magnetic behavior was seen around 75K. This anomalous behavior indicates towards a structural phase transition. However, the low temperature XRD could not confirm this observation.

Kanrar, Buddhadev, E-mail: nlmisra@barc.gov.in; Misra, N. L., E-mail: nlmisra@barc.gov.in [Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Sastry, P. U. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai-400085 (India); Dube, V.; Ravikumar, G. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai-400085 (India)

2014-04-24

166

A comparison between magnetic and reflection loss characteristics of substituted strontium ferrite and nanocomposites of ferrite/carbon nanotubes  

NASA Astrophysics Data System (ADS)

Large-scale carbon nanotubes (CNTs)/substituted strontium ferrite nanocomposites have been fabricated by hetero-coagulation. The structure and morphology of nanoparticles and nanocomposites were evaluated by high-resolution transmission electron microscopy (HRTEM). HRTEM confirmed that strontium ferrite was successfully attached to carbon nanotubes. The vibrating sample magnetometer (VSM) confirmed the relatively strong dependence of saturation magnetization with the volume percentage of multi-walled carbon nanotubes (MWCNTs). Reflection loss of nanocomposites at 12-18 GHz was evidently enhanced, as compared to that of strontium ferrite nanoparticles. The maximum reflection loss increased significantly with an increase in volume percentage of MWCNTs. It was proved that the microwave absorbing bandwidth was modulated simply by manipulating the thickness of nanocomposites. Reflection loss evaluations indicate that the nanocomposites display a great potential application as wide-band electromagnetic wave absorbers.

Ghasemi, Ali; Shirsath, Sagar E.; Liu, Xiaoxi; Morisako, Akimitsu

2012-04-01

167

Local Structures of Mechanically Alloyed Al70Cu20Fe10 Nanocomposites Studied by XRD and XAFS  

SciTech Connect

Ternary Al70Cu20Fe10 alloy nano-composites prepared by mechanical alloying are characterized by X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS). The results indicate that after milled for 10 hours, the coordination environment around Cu atoms is changed largely and becomes disordered, but the local structure of Fe atoms still remains as that of {alpha}-Fe. This indicates the forming of inter-metallic compound Al2Cu with body center cubic structure. Even if the milling time is extended to 40 hours, only small amount of {alpha}-Fe can be alloyed to produce Al-Fe-Cu alloy. However, the annealing treatment at 700 deg. C can drive the {alpha}-Fe to incorporate into the Al2Cu compound to form an icosahedral alloy phase.

Yin Shilong; Qian Liying [Institute of Science, Hohai University, Nanjing 210098 (China); He Bo; Zou Shaobo; Wei Shiqiang [National Synchrotron. Radiation Laboratory, University of Science and Technology of China, Hefei, 230029 (China); Bian Qing [Institute of Science, PLAUST, Nanjing 210007 (China)

2007-02-02

168

Changes in the surfaces on DDOAB organoclays adsorbed with paranitrophenol-An XRD, TEM and TG study  

SciTech Connect

The adsorption of paranitrophenol on organoclays synthesised by the ion exchange of the surfactant molecule dimethyldioctadecylammonium bromide (DDOAB) of formula (CH{sub 3}(CH{sub 2}){sub 17}){sub 2}NBr(CH{sub 3}){sub 2} has been studied by X-ray diffraction (XRD), transmission electron microscopy (TEM) and thermogravimetric analysis. The expansion of the montmorillonite depends on the loading of the montmorillonite with dimethyldioctadecylammonium bromide and is related to the arrangement of the surfactant molecules within the clay interlayer. This expansion is altered by the adsorbed paranitrophenol and is observed in the transmission electron microscopic images of the organoclay with adsorbed paranitrophenol. Changes in the surfactant molecular arrangements were analysed by thermogravimetry. The paranitrophenol is sublimed simultaneously with the loss of surfactant. The dehydroxylation temperature of the montmorillonite is decreased upon adsorption of the paranitrophenol indicating a bonding between the paranitrophenol and the hydroxyl units of the montmorillonite.

Zhou Qin [Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001 (Australia); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); He Hongping [Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001 (Australia); Frost, Ray L. [Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001 (Australia)], E-mail: r.frost@qut.edu.au; Xi Yunfei [Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, QLD 4001 (Australia); Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA 5095 (Australia)

2008-12-01

169

A combined XAS and XRD study of the high-pressure behaviour of GaAsO4 berlinite  

NASA Astrophysics Data System (ADS)

Combined X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) ex peri ments have been carried out on ?-GaAsO4 (berlinite structure) at high pressure and room temperature. XAS measurements indicate four-fold to six-fold coordination changes for both cations. The two local coordination transformations occur at different pressure rates but appear to be coupled. A reversible transition to a high-pressure crystalline form occurs around 8 GPa. At a pressure of about 12 GPa, the system mainly consists of octahedral gallium atoms and a mixture of arsenic in four-fold and six-fold coordinations. A second transition to a highly disordered material with both cations in six-fold coordination occurs at higher pressures and is irreversible.

Badro, J.; Gillet, Ph.; McMillan, P. F.; Polian, A.; Itié, J.-P.

1997-12-01

170

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

SciTech Connect

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.

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

2000-01-17

171

Characterization of minerals in air dust particles in the state of Tamilnadu, India through FTIR, XRD and SEM analyses  

NASA Astrophysics Data System (ADS)

The abstract of this paper explains the presence of minerals in air which causes great concern regarding public health issues. The spectroscopic investigation of air dust particles of several samples in various locations in the state of Tamilnadu, India is reported. Qualitative analyses were carried out to determine the major and minor constituent minerals present in the samples based on the FTIR, XRD absorption peaks. This study also identified the minerals like quartz, asbestos, kaolinite, calcite, hematite, montmorillonite, nacrite and several other trace minerals in the air dust particles. The presents of quartz is mainly found in all the samples invariably. Hence the percentage of quartz and its crystalline nature were determined with the help of extinction co-efficient and crystallinity index respectively. The shape and size of the particulates are studied with SEM analysis.

Senthil Kumar, R.; Rajkumar, P.

2014-11-01

172

The presence of mercury selenide in various tissues of the striped dolphin: evidence from ?-XRF-XRD and XAFS analyses.  

PubMed

Marine mammals accumulate mercury in their tissues at high concentration and detoxify by forming mercury selenide (HgSe, tiemannite) mainly in the liver. We investigated the possibility of formation of HgSe in various tissues (liver, kidney, lung, spleen, pancreas, muscle and brain) other than the liver of the striped dolphin (Stenella coeruleoalba). We applied a combination method of micro-X-ray fluorescence (?-XRF) imaging and micro-X-ray diffraction (?-XRD) using a synchrotron radiation X-ray microbeam to analyze the tissue samples directly with minimal sample preparation. By this method, many accumulation points for Hg and Se on a micron scale were found in thin sections of the spleen and liver tissue and consequently, the XRF spectra and the XRD pattern of the hot spots confirmed the presence of tiemannite, HgSe. On the other hand, the insoluble fractions after enzyme digestion of the nuclear and mitochondrial fractions of all tissues were subjected to X-ray absorption fine structure (XAFS) analysis. XAFS analysis confirmed the presence of HgSe in all the tissues examined (liver, kidney, lung, spleen, pancreas, muscle and brain) of the striped dolphin. The presence of HgSe in all the tissues examined suggests that Se would be involved in the detoxification process of Hg in various tissues other than the liver. This contribution seems to be large especially in the liver and spleen but relatively small in the kidney, pancreas and brain, because the proportion of insoluble fraction containing HgSe was lower in these tissues (25 to 46%). This is the first report on the presence of tiemannite HgSe in various tissues of marine mammals. PMID:21468440

Nakazawa, Emiko; Ikemoto, Tokutaka; Hokura, Akiko; Terada, Yasuko; Kunito, Takashi; Tanabe, Shinsuke; Nakai, Izumi

2011-07-01

173

Combination of optical and X-ray techniques in the study of amorphous semiconductors under high pressure: an upgrade setup for combined XAS and XRD measurements  

Microsoft Academic Search

X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) are complementary techniques whose combination is a powerful tool of investigation of matter under extreme conditions (high pressure, high temperature). The standard setup at the ODE beamline (Soleil Synchrotron) has been modified in order to allow the performance of simultaneous XAS\\/XRD measurements on the same sample. These techniques, together with Raman spectroscopy

F. Coppari; A. di Cicco; E. Principi; A. Trapananti; N. Pinto; A. Polian; S. Chagnot; A. Congeduti

2010-01-01

174

The importance of XRD analysis in provenance and palaeoenvironmental studies of the Piedras de Afilar Formation, Neoproterozoic of Uruguay  

NASA Astrophysics Data System (ADS)

The Piedras de Afilar Formation crops out in the southeast part of Uruguay, forming part of the Tandilia Terrane (sensu Bossi et al. 2005). Pamoukaghlian et al. (2006) and Gaucher et al. (2008) have published ?13C, ?18O and U/Pb SHRIMP results, which indicate a Neoproterozoic age for this formation. The palaeoenvironment has been defined as a shallow marine platform based on the presence of interference ripples, hummocky and mega-hummocky cross-stratification. X-ray diffraction (XRD) analyses help to better constrain the palaeoenvironment: the presence of chlorite/smectite found in black shales, suggest a reducing environment, and abundant illite indicates a cold to temperate climate. Provenance studies have been undertaken that utilise a combination of detailed palaeocurrent measurements, petrographic descriptions, XRD analyses, and geochemical isotopic analyses, including U/Pb SHRIMP determinations. Mineral compositional diagrams for sandstones suggest a stable cratonic provenance. Palaeocurrents are mainly from the NNE, indicating a provenance from the cratonic areas of the Tandilia Terrane. The illite crystal index indicates diagenetic to low-metamorphic conditions for the sequence; this is important to confirm that the identified minerals are authigenic. Clay minerals identified by XRD analysis of sandstones from the siliciclastic member are illite (80 - 90%), kaolinite (5 - 10%), and chlorite (5 - 10%). This is consistent with a provenance from the cratonic areas (quartz-feldspar dominated rock types). Isotopic analyses have been undertaken to provide better constraints on the tectonic setting. U/Pb SHRIMP ages for the youngest zircons are 990 Ma (Gaucher et al. 2008), and the basal granite (Granito de la Paz) is 2056 ± 11 Ma (Hartmann et al. 2001), suggesting a provenance from the Archaean basement for the Piedras de Afilar Formation, like its counterparts in the Rio de la Plata Craton. References Bossi, J., Piñeyro, D., Cingolani, C. (2005). El límite norte del Terreno Piedra Alta (Uruguay). Importancia de la faja milonítica sinestral de Colonia. Actas XVI Congreso Argentino de Geología, de La Plata. Gaucher, C., Poiré, D.G., Finney, S.C., Valencia, V.a., Blanco, G., Pamoukaghlian, K., Gómez Peral, L. (2008). Detrital zircón ages of Neoproterozoic sedimentary successions in Uruguay and Argentina: Insights into the geological evolution of the Rio de la Plata Craton. Precambrian Research. Hartmann, L.A., Campal, N., Santos, J.O., Mc. Neughton, N.J., Schipilov, A., Lafon, J.M. (2001). Archean crust in the Rio de la Plata Craton, Uruguay - SHRIMP U-Pb zircon reconnaissance geochronology. Journal of South American Earth Science, 14, 557-570. Pamoukaghlian, K., Gaucher, C., Bossi, J., Sial, N., Poire, D.G. (2006). First C and O isotopic data for the Piedras de Afilar Formation, Tandilia Terrane, Uruguay: their bearing on correlation and age. Fifth South American Symposium on Isotope Geology, Punta del Este.

Pamoukaghlian, K.; Poiré, D. G.; Gaucher, C.; Uriz, N.; Cingolani, C.; Frigeiro, P.

2009-04-01

175

Weathering and hydrothermal alteration of basalts in Iceland: mineralogy from VNIR, TIR, XRD, and implications for Mars  

NASA Astrophysics Data System (ADS)

Recent orbital investigations have revealed that aqueous alteration on early Mars took place in diverse alteration environments indicated by distinctive assemblages of minerals (Murchie et al., 2009, JGR). There is growing evidence for past diagenetic or low-temperature/pressure hydrothermal activity on Mars at neutral to alkaline pH, indicated by the presence of Fe/Mg smectites, chlorite, prehnite, serpentine, opaline silica, and zeolites such as analcime in Noachian terrains (Ehlmann et al., 2009, JGR). In recent investigations of terrestrial Mars analog sites, neutral to alkaline pH alteration of basalt, both pedogenic and hydrothermal, has been understudied in favor of sulfur-rich, acidic systems including those at the Hawaiian volcanoes and Rio Tinto, Spain. We began study of the alteration of basalt lava flows in Iceland as a geochemical analog for Noachian Mars. Because the basaltic bedrock is recently formed (<16Ma) with few localities of more highly evolved composition and has poorly formed soils and spare vegetation, the ground and surface waters are broadly similar to those which might have existed on Noachian Mars. Iceland has a variety of geothermal spring systems--low T, low S; low T, high S; and high T, high S--each of which creates distinctive mineralogic assemblages. Here we examine rocks of the Hvalfjordur peninsula, collected from basalt flows that were in some places altered at the surface by pedogenesis and in other locations were hydrothermally altered by non-sulfurous groundwater circulation (low T, low S) following the emplacement of a later hot basalt flow. Rock samples were surveyed in the field using a portable VNIR spectrometer. Altered and unaltered rocks that were typical for the locality were collected as were altered rocks whose spectra were most similar to those measured by CRISM from Mars orbit. Ten rocks were ultimately selected for detailed laboratory analyses: zeolitized basaltic rocks bearing minerals including analcime and thomsonite, basalts with silica/quartz-bearing veins, basalts bearing celadonite, and basalts partially altered to montmorillonite, Fe/Mg smectite, or mixed smectite-chlorite. Analyses included: (1) measurement of reflectance spectra of the whole rock by the ASD; (2) measurement of VNIR and TIR spectra in RELAB of particle-size separates (<25um and <125um) derived from the bulk rock and from precipitated minerals extracted from the vesicles; (3) measurement of X-ray diffraction (XRD) patterns, including quantitative XRD; and (4) electron microprobe chemical analyses. These data emulate orbital data from CRISM, OMEGA, and TES, which detect the infrared active components, linked to in-situ data on whole rock modal mineralogy such as will be measured by the ChemMin instrument on the MSL rover.

Ehlmann, B. L.; Mustard, J. F.; Bish, D. L.

2009-12-01

176

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

SciTech Connect

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.

Garza-Navarro, Marco [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Universidad s/n, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Torres-Castro, Alejandro, E-mail: alejandro.torrescs@uanl.edu.m [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Universidad s/n, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon 66600 (Mexico); Gonzalez, Virgilio; Ortiz, Ubaldo [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Universidad s/n, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon 66600 (Mexico); De la Rosa, Elder [Centro de Investigaciones en Optica, A.P. 1-948, Leon Gto. 37160 (Mexico)

2010-01-15

177

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

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

178

Investigation on the effects of milling atmosphere on synthesis of barium ferrite\\/magnetite nanocomposite  

Microsoft Academic Search

In this research, barium ferrite \\/magnetite nanocomposites synthesized via a mechano-chemical route.\\u000aGraphite was used in order to reduce hematite content of barium ferrite to magnetite to produce a magnetic nanocomposite. The effects of processing conditions on the powder characteristics were investigated by XRD, VSM, and HRTEM techniques. XRD results revealed that milling under air and argon atmospheres resulted in

M. J. Molaei; A. Ataie; S. Raygan; n S. J. Picken

2011-01-01

179

Mercury in polluted soils: speciation using micro-XRF, micro-XRD, and micro- and bulk XAFS.  

NASA Astrophysics Data System (ADS)

In this research, mercury speciation was assessed for soil samples collected inside and outside an industrial polluted area of National environmental interest located in "Val Basento" (Basilicata, Italy). Hg concentration in these soil samples ranged from 12 up to 240 mg/kg. Mercury chemical forms in these samples were identified by a combination of sequential extraction procedures, thermal desorption analyses, and different bulk- and micro-analytical techniques exploiting high intensity synchrotron generated X-rays. Bulk XANES (X-ray Absorption Near Edge Structure) and EXAFS (Extended X-ray Absorption Fine Structure) spectra were collected for direct Hg-speciation in soil samples sieved at 2mm as well as in the clay fraction (<2um), where the highest amount of mercury was concentrated. The interpretation of the complex mixture of Hg-chemical forms in the soil samples was made simpler by performing, beside bulk XAS investigations, microanalyses on soil thin sections by combined u-XRF/u-XRD (micro X-ray Fluorescence/micro X-ray Diffraction) and u-XANES, with a resolution of 20 um. The information deriving from the micro-scale was then used to understand the bulk data. m-XRF maps were collected to localize microscopic Hg-containing particles in areas of several hundreds of mm2. Simultaneous to u-XRF spectra, microdiffraction patterns were collected in each point of the map, to identify possible crystalline Hg-mineral forms or mineral associations. Once points of interest were localized, u-XANES spectra were also collected. In general, two main representative XANES spectra (S1 and S2) were observed from Hg-rich spots at the microscopic level. Interestingly, all the bulk XANES spectra from all soil samples could be fitted by a linear combination of the microscopic S1 and S2 spectra. Therefore, by fitting the S1 and S2 spectra by means of known standard spectra it was then possible to decipher Hg-speciation for all the soil samples. In conclusion, the main constituents in the soil samples were cinnabar (HgS), metacinnabar, corderoite (Hg3S2Cl2), and amorphous Hg-S-Cl phases, in different proportions. The presence of these amorphous forms was suggested by EXAFS and XRD structural analyses. The speciation obtained is also in agreement with the chemical behaviour of the soil samples as assessed by sequential extractions and thermal desorption analyses. The chemical species identified are typical of soils contaminated with wastes produced by chlor-alkali plants. Actually, a chlor-alkali plant was active in the area during the 1960-80's, and now is no more existing. In conclusion, notwithstanding the diffuse Hg-pollution in the investigated area, it seems that Hg is speciated in scarcely soluble and hardly mobilisable forms. The determination of the chemical forms of toxic elements in polluted soils is an indispensable step to identify the source of pollution, to formulate a correct risk assessment and to develop effective remediation strategies.

Terzano, R.; Santoro, A.; Spagnuolo, M.; Vekemans, B.; Medici, L.; Janssens, K.; Goettlicher, J.; Denecke, M. A.; Mangold, S.; Ruggiero, P.

2009-04-01

180

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

SciTech Connect

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.

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

2003-01-01

181

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

SciTech Connect

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.

Chetty, Raju, E-mail: rcmallik@physics.iisc.ernet.in; Mallik, Ramesh Chandra, E-mail: rcmallik@physics.iisc.ernet.in [Department of Physics, Indian Institute of Science, Bangalore-560012 (India)

2014-04-24

182

Magnetically separable composite photocatalyst with enhanced photocatalytic activity.  

PubMed

A novel magnetically separable composite photocatalyst, anatase titania-coated magnetic activated carbon (TMAC), was prepared in this article. In the synthesis, magnetic activated carbon (MAC) was firstly obtained by adsorbing magnetic Fe3O4 nanoparticles onto the activated carbon (AC), and then the obtained MAC was directly coated by anatase titania nanoparticles prepared at low temperature (i.e. 75 degrees C). The prepared samples were characterized by XRD, SEM and vibrating sample magnetometer (VSM). The composite photocatalyst can be easily separated from solution by a magnet, its photocatalytic activity in degradation of phenol in aqueous solution also has dramatic enhancement compared to that of the neat titania. PMID:18406055

Ao, Yanhui; Xu, Jingjing; Shen, Xunwei; Fu, Degang; Yuan, Chunwei

2008-12-30

183

Sol-gel synthesis of Fe-Co nanoparticles and magnetization study  

NASA Astrophysics Data System (ADS)

We report the synthesis of carbon encapsulated Fe-Co nanoparticles using conventional sol-gel route and its magnetization studies. The x-ray diffraction indicates the formation of the single phase body centered cubic alloy Fe-Co phase with cell parameter of 2.857 Å. Nanoparticles are highly crystalline and exhibit low index faceting as determined from high-resolution transmission electron microscopy (HRTEM) investigation. The observed orthogonal lattice planes with lattice distance of 2.86 Å are attributed to (100) and (010). HRTEM image confirms the cube like Fe-Co nanoparticles with core-shell structure of carbon encapsulation, composed of carbon and graphite materials. The magnetometry results of the carbon encapsulated alloy Fe-Co nanoparticles with core-shell structure designate as a ferromagnetically ordered soft magnet with coercive field of 890 Oe (at 5 K). The coercive field and magnetization value depend on the size of nanoparticles as well as the diamagnetic contribution of carbon encapsulation.

Nautiyal, Pranjal; Seikh, Md. Motin; Lebedev, Oleg I.; Kundu, Asish K.

2015-03-01

184

The effect of humidity on dehydration behavior of nitrofurantoin monohydrate studied by humidity controlled simultaneous instrument for X-ray Diffractometry and Differential Scanning Calorimetry (XRD–DSC)  

Microsoft Academic Search

The dependence of thermal dehydration behavior of nitrofurantoin monohydrate on humidity was studied. Difference in observed crystallinity of resulting anhydrates under three humidity conditions is discussed in relation to the effect of water vapor molecules. Thermal dehydration of nitrofurantoin monohydrate was measured using a humidity controlled simultaneous measurement instrument for X-ray Diffractometry (XRD) and Differential Scanning Calorimetry (DSC) in dry,

Akira Kishi; Makoto Otsuka; Yoshirisa Matsuda

2002-01-01

185

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

NASA Astrophysics Data System (ADS)

The CheMin 4 XRD/XRF prototype was deployed in Rio Tinto, Spain, for a field campaign to study river bed sediments and test the potential of an instrument suite in an astrobiological investigation context for future Mars surface robotic missions.

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

2007-03-01

186

XRD measurement of mean thickness, thickness distribution and strain for illite and illite-smectite crystallites by the Bertaut-Warren-Averbach technique  

USGS Publications Warehouse

A modified version of the Bertaut-Warren-Averbach (BWA) technique (Bertaut 1949, 1950; Warren and Averbach 1950) has been developed to measure coherent scattering domain (CSD) sizes and strains in minerals by analysis of X-ray diffraction (XRD) data. This method is used to measure CSD thickness distributions for calculated and experimental XRD patterns of illites and illite-smectites (I-S). The method almost exactly recovers CSD thickness distributions for calculated illite XRD patterns. Natural I-S samples contain swelling layers that lead to nonperiodic structures in the c* direction and to XRD peaks that are broadened and made asymmetric by mixed layering. Therefore, these peaks cannot be analyzed by the BWA method. These difficulties are overcome by K-saturation and heating prior to X-ray analysis in order to form 10-A?? periodic structures. BWA analysis yields the thickness distribution of mixed-layer crystals (coherently diffracting stacks of fundamental illite particles). For most I-S samples, CSD thickness distributions can be approximated by lognormal functions. Mixed-layer crystal mean thickness and expandability then can be used to calculate fundamental illite particle mean thickness. Analyses of the dehydrated, K-saturated samples indicate that basal XRD reflections are broadened by symmetrical strain that may be related to local variations in smectite interlayers caused by dehydration, and that the standard deviation of the strain increases regularly with expandability. The 001 and 002 reflections are affected only slightly by this strain and therefore are suited for CSD thickness analysis. Mean mixed-layer crystal thicknesses for dehydrated I-S measured by the BWA method are very close to those measured by an integral peak width method.

Drits, V.A.; Eberl, D.D.; Srodon, J.

1998-01-01

187

Structural and magnetic properties of granular Co-Pt multilayers with perpendicular magnetic anisotropy  

NASA Astrophysics Data System (ADS)

We present a study of granular Co-Pt multilayers by means of high-resolution transmission electron microscopy (HRTEM), extended x-ray absorption fine structure (EXAFS), SQUID-based magnetic measurements, anomalous Hall effect (AHE), and x-ray magnetic circular dichroism (XMCD). We describe these granular films as composed of particles with a pure cobalt core surrounded by an alloyed Co-Pt interface, embedded in a Pt matrix. The alloy between the Co and Pt in these granular films, prepared by room temperature sputter deposition, results from interdiffusion of the atoms. The presence of this alloy gives rise to a high perpendicular magnetic anisotropy (PMA) in the granular films, as consequence of the anisotropy of the orbital moment in the Co atoms in the alloy, and comparable to that of highly-ordered CoPt L 10 alloy films. Their magnetic properties are those of ferromagnetically coupled particles, whose coupling is strongly temperature dependent: at low temperatures, the granular sample is ferromagnetic with a high coercive field; at intermediate temperatures the granular film behaves as an amorphous asperomagnet, with a coupling between the grains mediated by the polarized Pt, and at high temperatures, the sample has a superparamagnetic behavior. The coupling/decoupling between the grains in our Co-Pt granular films can be tailored by variation of the amount of Pt in the samples.

Figueroa, A. I.; Bartolomé, J.; García, L. M.; Bartolomé, F.; Bun?u, O.; Stankiewicz, J.; Ruiz, L.; González-Calbet, J. M.; Petroff, F.; Deranlot, C.; Pascarelli, S.; Bencok, P.; Brookes, N. B.; Wilhelm, F.; Smekhova, A.; Rogalev, A.

2014-11-01

188

Effect of Ferritic Density and Zinc on Magnetic Properties of Cobalt Ferrite Nanocomposites  

Microsoft Academic Search

Cobalt ferrite nanocomposite was investigated for RF applications. Magnetic nanocomposites were fabricated at different ferritic densities. Cobalt zinc ferrite nanocomposite was also prepared to study the effect of zinc. The size of magnetic nanoparticle was measured by transmission electron microscopy (TEM), while its crystalline structure was characterized by X-ray diffraction (XRD). Toroidal sample was made by compact method. The density

Hai Dong; A. Meininger; Kyoung-Sik Moon; L. Martin; C. P. Wong

2006-01-01

189

Electrical and magnetic characterization of nanocrystalline Ni–Zn ferrite synthesis by co-precipitation route  

Microsoft Academic Search

Nickel zinc ferrite nanoparticles Ni1?xZnxFe2O4 (x=0.25, 0.5, 0.75, 1) have been prepared by the chemical co-precipitation route. The samples were characterized by X-ray diffraction (XRD), DC electrical resistivity, dielectric constant and low field AC magnetic susceptibility. The powder XRD patterns confirm the single phase spinel structure for the synthesized materials. The crystallite size was calculated from the most intense peak

I. H. Gul; W. Ahmed; A. Maqsood

2008-01-01

190

Synthesis and Characterization of Magnetic Metal-encapsulated Multi-walled Carbon Nanobeads  

PubMed Central

A novel, cost-effective, easy and single-step process for the synthesis of large quantities of magnetic metal-encapsulated multi-walled carbon nanobeads (MWNB) and multi-walled carbon nanotubes (MWNT) using catalytic chemical vapour deposition of methane over Mischmetal-based AB3alloy hydride catalyst is presented. The growth mechanism of metal-encapsulated MWNB and MWNT has been discussed based on the catalytically controlled root-growth mode. These carbon nanostructures have been characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM and HRTEM), energy dispersive analysis of X-ray (EDAX) and thermogravimetric analysis (TGA). Magnetic properties of metal-filled nanobeads have been studied using PAR vibrating sample magnetometer up to a magnetic field of 10 kOe, and the results have been compared with those of metal-filled MWNT.

2008-01-01

191

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

NASA Astrophysics Data System (ADS)

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.

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

2010-01-01

192

Synthesis, characterization and magnetic properties of Fe3O4 doped chitosan polymer  

NASA Astrophysics Data System (ADS)

Fe3O4 nanoparticles doped into chitosan films were prepared by the solution casting technique. Various samples were synthesized in atmospheric medium and in vacuum. The morphological properties of the samples were characterized by high resolution transmission electron microscopy (HR-TEM) and Scanning Electron Microscopy (SEM). The structural, magnetic, and microwave absorption properties of magnetic chitosan films have been carried out using the Vibrating Sample Magnetometer (VSM) and Ferromagnetic Resonance (FMR). It is shown that the composite polymer behaves like a superparamagnetic material with high blocking temperature. The effective magnetization shows gradual increments with the concentration of dopant Fe3O4 nanoparticles. The microwave absorption characteristic of superparamagnetic composite polymer shows low reflection loss.

Karaca, E.; ?at?r, M.; Kazan, S.; Aç?kgöz, M.; Öztürk, E.; Gürda?, G.; Uluta?, D.

2015-01-01

193

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)

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.

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

2013-12-01

194

Studies of zinc-blende type MnAs thin films grown on InP(001) substrates by XRD  

NASA Astrophysics Data System (ADS)

The detailed crystalline structure of molecular beam epitaxially grown MnAs thin films on InP(001) substrate has been investigated using high resolution X-ray diffraction techniques. Reciprocal space mapping of the MnAs/InP(001) samples indicates that the MnAs has a cubic zinc-blende (zb) structure with the epitaxial relationship zb-MnAs[110]|InP[110]. The lattice constant of zb-MnAs is ˜6.06 Å. The MnAs lattice is relaxed and is mosaic-like likely due to large lattice mismatch between the film and InP substrate. The isotropic nature of the magnetic properties supported our conjecture that the MnAs epitaxial film under study has indeed a cubic structure.

Oomae, H.; Irizawa, S.; Jinbo, Y.; Toyota, H.; Kambayashi, T.; Uchitomi, N.

2013-09-01

195

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)

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.

Ferraris, Cristiano; Lorand, Jean-Pierre

2014-08-01

196

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

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.

Castro, Nelia, E-mail: nelia.castro@ntnu.no [Norwegian University of Science and Technology (NTNU), Department of Geology and Mineral Resources Engineering, Sem Saelands vei 1, N-7491 Trondheim (Norway)] [Norwegian University of Science and Technology (NTNU), Department of Geology and Mineral Resources Engineering, Sem Saelands vei 1, N-7491 Trondheim (Norway); Sorensen, Bjorn E. [Norwegian University of Science and Technology (NTNU), Department of Geology and Mineral Resources Engineering, Sem Saelands vei 1, N-7491 Trondheim (Norway)] [Norwegian University of Science and Technology (NTNU), Department of Geology and Mineral Resources Engineering, Sem Saelands vei 1, N-7491 Trondheim (Norway); Broekmans, Maarten A.T.M. [Geological Survey of Norway, Department of Industrial Minerals and Metals, PO Box 6315 Sluppen, N-7491 Trondheim (Norway)

2012-11-15

197

Silica-encapsulated magnetic nanoparticles: enzyme immobilization and cytotoxic study.  

PubMed

Silica-encapsulated magnetic nanoparticles (MNPs) were prepared via microemulsion method. The products were characterized by high resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray spectrum (EDS). MNPs with no observed cytotoxic activity against human lung carcinoma cell and brine shrimp lethality were used as suitable support for glucose oxidase (GOD) immobilization. Binding of GOD onto the support was confirmed by the FTIR spectra. The amount of immobilized GODs was 95 mg/g. Storage stability study showed that the immobilized GOD retained 98% of its initial activity after 45 days and 90% of the activity was also remained after 12 repeated uses. Considerable enhancements in thermal stabilities were observed for the immobilized GOD at elevated temperatures up to 80°C and the activity of immobilized enzyme was less sensitive to pH changes in solution. PMID:22269345

Ashtari, Khadijeh; Khajeh, Khosro; Fasihi, Javad; Ashtari, Parviz; Ramazani, Ali; Vali, Hojatollah

2012-05-01

198

Studies of Fe 3O 4-chitosan nanoparticles prepared by co-precipitation under the magnetic field for lipase immobilization  

Microsoft Academic Search

A simple method was introduced to prepare magnetic Fe3O4-chitosan nanoparticles by co-precipitation with 0.45T static magnetic field via glutaraldehyde cross-linking reaction, and the nanoparticles were used to immobilize lipase. The influence of magnetic field on the properties of magnetic nanoparticles was studied by SEM, XRD and VSM. The results showed that no obvious difference of the nanoparticles structure was found,

Yong Liu; Shaoyi Jia; Qian Wu; Jingyu Ran; Wei Zhang; Songhai Wu

2011-01-01

199

Microstructure of multistage annealed nanocrystalline SmCo{sub 2}Fe{sub 2}B alloy with enhanced magnetic properties  

SciTech Connect

The microstructure and chemistry of SmCo{sub 2}Fe{sub 2}B 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){sub 4}B (1:4:1) and Sm{sub 2}(Co,Fe){sub 17}B{sub x} (2:17:x) magnetic phases were confirmed using both techniques. Fe{sub 2}B 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.

Jiang, Xiujuan, E-mail: xiujuan.jiang@Huskers.unl.edu; Shield, Jeffrey E. [Department of Mechanical and Materials Engineering, University of Nebraska, Lincoln, Nebraska 68588 (United States); Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588 (United States); Devaraj, Arun [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99354 (United States); Balamurugan, B. [Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588 (United States); Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588 (United States); Cui, Jun [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354 (United States)

2014-02-14

200

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)

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.

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

201

MAGNETIC MOMENT AND MAGNETIZATION  

E-print Network

Magnetism has engaged explorers and scientists for over two millennia. The ancient Greeks and Turks noted the attraction between magnetite (lodestone) and iron (Cullity and Graham, 1978). Explorers used lodestone’s

Michael E. Mchenry; David; E. Laughlin

202

Mars Magnetism  

Microsoft Academic Search

The Mars Global Surveyor Magnetic Field Investigation (PI: Acuna) has mapped the crustal magnetic field with unprecedented signal fidelity and resolution from its 400 km altitude orbit. The crust is intensely magnetized, at least an order of magnitude more intensley magnetized than Earth's, and even from orbital altitude one recognizes order in the spatial variation of the magnetic field. We

J. Connerney

2003-01-01

203

Magnetic Levitation.  

ERIC Educational Resources Information Center

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

Rossing, Thomas D.; Hull, John R.

1991-01-01

204

Magnetic Pendulum  

NSDL National Science Digital Library

In this activity about magnetism (page 15 of the PDF), learners will explore how opposite and similar magnetic poles affect a swinging (pendulum) magnet. Learners will see firsthand how gravity and magnetism can work together to create a chaotic system. This is an excellent activity for experimenting with different variables to see how they affect the overall movement of a magnet.

Cosi

2009-01-01

205

New Tc-tuned magnetic nanoparticles for self-controlled hyperthermia  

NASA Astrophysics Data System (ADS)

Manganese perovskite nanoparticles of the XRD size in the range of 30-49 nm were synthesized via sol-gel technique employing citric acid and ethylene glycol. Their magnetic properties were investigated in the static and alternating magnetic fields. Particular attention was paid to the relation between the size of particles and resulting magnetic power losses, measured by the calorimetric heating experiments on the stable water suspensions and of the hysteresis loops in the alternating fields on powdered samples.

Pollert, E.; Knížek, K.; Maryško, M.; Kašpar, P.; Vasseur, S.; Duguet, E.

2007-09-01

206

Electronic and magnetic properties of Co-doped ZnO diluted magnetic semiconductor  

Microsoft Academic Search

The effect of low level Co doping (5%) on polycrystalline ZnO samples has been investigated to correlate the observed changes in their magnetic state vis à vis changes in their electronic properties. Rietveld refinement of the XRD patterns confirms single phase crystallization of the samples in the wurtzite type lattice, with no evidence of any secondary phases. The as-synthesized Co-doped

R. K. Singhal; Arvind Samariya; Y. T. Xing; Sudhish Kumar; S. N. Dolia; U. P. Deshpande; T. Shripathi; Elisa B. Saitovitch

2010-01-01

207

Magnetic testing  

NASA Technical Reports Server (NTRS)

Magnetic techniques are described for the nondestructive evaluation of defects in materials. The physical principles, and the magnetic-particle method are discussed along with magnetic-hysteresis measurements and electric current perturbations.

Pasley, R. L.; Barton, J. R.

1973-01-01

208

Magnetic Attraction  

NSDL National Science Digital Library

Students complete a series of six short investigations involving magnets to learn more about their properties. Students also discuss engineering uses for magnets and brainstorm examples of magnets in use in their everyday lives.

Integrated Teaching and Learning Program,

209

Magnetic Properties of Nanocrystalline Nickel-Cobalt Ferrites  

NASA Astrophysics Data System (ADS)

In this study, the nanocrystalline nickel-cobalt ferrites were prepared via the citrate route method at . The samples were calcined at for 3 h. The crystalline structure and the single-phase formations were confirmed by X-ray diffraction (XRD) measurements. Prepared materials showed the cubic spinel structure with m3m symmetry and Fd3m space group. The analyses of XRD patterns were carried out using POWD software. It gave an estimation of lattice constant “” of 8.3584 Å, which was in good agreement with the results reported in JCPDS file no. 742081. The crystal size of the prepared materials calculated by Scherer’s formula was 27.6 nm and the electrical conductivity was around . The permeability component variations with frequency were realized. The magnetic properties of the prepared materials were analyzed by a vibrating sample magnetometer (VSM). It showed a saturation magnetization of and the behavior of a hard magnet.

Tiwari, D. K.; Villaseñor-Cendejas, L. M.; Thakur, A. K.

2013-09-01

210

Magnets & Magnet Condensed Matter Science  

E-print Network

in Graphene on Boron Nitride 12 Magneto-elastic Coupling in Magnetically Frustrated Co3V2O8 13 FieldMagnets & Magnet Materials PAGE 29 Chemistry PAGE 35 Condensed Matter Science PAGE 6 Volume 18 No 18 No. 1 CONDENSED MATTER SCIENCE Technique development, graphene, magnetism & magnetic materials

McQuade, D. Tyler

211

Neodymium Magnets.  

ERIC Educational Resources Information Center

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)

Wida, Sam

1992-01-01

212

XRD and xanes studies of copper complexes using (diethyl 4-amino-1-phenyl-1H-pyrazole-3,5 dicarboxylate) as ligand  

NASA Astrophysics Data System (ADS)

X-ray diffraction (XRD) and X-ray absorption spectroscopic (XAS) studies have been done on three copper complexes using (diethyl 4-amino-1-phenyl-1H-pyrazole-3,5 dicarboxylate) as ligand. The X-ray diffraction studies of copper complexes have been recorded using Rigaku RINT-2000 X-ray diffractometer equipped with a rotating anode with tube voltage of 40 kV and current of 100 mA. The X-ray absorption spectra of the complexes have been recorded at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore and is called beamline.

Mishra, Ashutosh; Jain, Garima

2013-06-01

213

Crystal hack' to predict h, k, l from 'c' as well as 'a' values for cubic and HCP binary alloy crystals from XRD data  

NSDL National Science Digital Library

'Crystal hack' by Dr M Kanagasabapathy is used to predict h, k, l from 'c' as well as 'a' values for cubic and HCP binary alloy crystals from XRD data (2-Theta diffraction and wavelength of X-rays). d-spacing and hkl can be predicted precisely. Inbuilt data base for some elemental crystal system is included. It can be a useful tool for powder diffraction researchers / students to predict or shift in diffraction angle with hkl indices for cube-HCP binary alloy crystals.

Dr. M. Kanagasabapathy

214

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)

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.

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

2015-01-01

215

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

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

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

2015-01-25

216

Magnetization Study of CoxCu1-x Nanoparticles  

NASA Astrophysics Data System (ADS)

Nanostructured CoCu granular alloys have been prepared by chemical reduction method using NaBH4 as a reducing agent and characterized by inductively coupled plasma optical emission spectroscopy (ICPOES), x-ray diffraction (XRD) and transmission electron microscopy (TEM) studies. Zero-field cooled and field cooled (ZFC/FC) magnetization study shows a blocking temperature distribution resulting from particle size distribution which is a characteristic of superparamagnetism. Magnetization study reveals that at low Co concentration, the alloy particles are superparamagnetic. At higher Co concentration the magnetization is combination of ferromagnetism (FM) and superparamagnetism (SPM). The coercive field is independent of Co concentration.

Dhara, Susmita; Chowdhury, Rajeswari Roy; Bandyopadhyay, Bilwadal

217

A new magnetic expanded graphite for removal of oil leakage.  

PubMed

Magnetic expanded graphite (MEG) was prepared using the blended calcination method under a nitrogen atmosphere. MEG was characterized by scanning electron microscope (SEM), X-ray powder diffraction (XRD), Raman spectroscopy, and vibrating sample magnetization (VSM). Results show that the cobalt ferrite nanoparticles were uniformly and efficiently deposited on expanded graphite (EG). The saturation magnetization reached 55.05 emu g(-1), and the adsorption capacity of MEG under the optimal condition was 35.72 g g(-1) for crude oil. PMID:24559739

Ding, Xiaohui; Wang, Rong; Zhang, Xin; Zhang, Yanzong; Deng, Shihuai; Shen, Fei; Zhang, Xiaohong; Xiao, Hong; Wang, Lilin

2014-04-15

218

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

NASA Astrophysics Data System (ADS)

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.

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

2011-06-01

219

Magnet Tower  

NSDL National Science Digital Library

In this activity, learners build magnetic towers to explore the forces and properties of magnets. This activity allows learners to experiment and play with magnets and feel first-hand the force of magnets pushing and pulling. Note: this activity requires the use of a drill and saw, which are not included in the cost of materials.

Workshop, Mission S.

2013-01-01

220

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

SciTech Connect

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.

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 [Departamento de Fisica e CICECO, Universidade de Aveiro, Campus de Santiago, P-3810-193 Aveiro (Portugal); Departmento de Quimica Fisica, Universidade de Vigo, 36310 Vigo (Spain); Instituto de Ciencia de Materiales de Aragon, Universidad de Zaragoza-CSIC, 50009 Zaragoza (Spain); Departmento de Quimica and CQ-VR, Universidade de Tras-os-Montes e Alto Douro, Quinta de Prados, Apartado 1013, 5001-801 Vila Real (Portugal)

2006-09-01

221

Fe-based bulk metallic glasses used for magnetic shielding  

NASA Astrophysics Data System (ADS)

The casting in complex shapes (tubullar) and the main magnetic properties of bulk metallic glasses (BMG) alloys from the ferromagnetic Fe-Cr-Ni-Ga-P-Si-C system, with a small adittion of Ni (3%) were studied. Samples as rods and sockets having the thickness up to 1 mm were obtained from master alloys by melt injection by low cooling rates into a Cu mold and annealed in order to ensure adequate magnetic requirements. The structure was examined by X-ray diffraction (XRD) and the basic magnetic properties (coercivity, magnetic remanence, initial susceptibility, etc.) were determined by conventional low frequency induction method. The experimental investigations on producing of BMG ferromagnetic alloys with 3% Ni show the possibility to obtain magnetic shields of complex shape with satisfactory magnetic properties. The presence of Ni does not affect the glass forming ability, but reduce the shielding capacity.

?erban, Va; Codrean, C.; U?u, D.; Ercu?a, A.

2009-01-01

222

Biosorption of copper(II) by immobilizing Saccharomyces cerevisiae on the surface of chitosan-coated magnetic nanoparticles from aqueous solution  

Microsoft Academic Search

Immobilized Saccharomyces cerevisiae on the surface of chitosan-coated magnetic nanoparticles (SICCM) was applied as a new magnetic adsorbent for the adsorption of Cu(II) from aqueous solution. The prepared magnetic adsorbent was characterized by TEM, XRD and FTIR. TEM images indicated that S. cerevisiae was immobilized on the surface of chitosan-coated magnetic nanoparticles (CCM) successfully, and conglobation was not observed. The

Qingqing Peng; Yunguo Liu; Guangming Zeng; Weihua Xu; Chunping Yang; Jingjin Zhang

2010-01-01

223

Removal of Cu 2+ from aqueous solution by chitosan-coated magnetic nanoparticles modified with ?-ketoglutaric acid  

Microsoft Academic Search

Chitosan-coated magnetic nanoparticles (CCMNPs), modified with a biodegradable and eco-friendly biologic reagent, ?-ketoglutaric acid (?-KA), was used as a magnetic nanoadsorbent to remove toxic Cu2+ ions from aqueous solution. The prepared magnetic nanoadsorbents were characterized by FTIR, TEM, VSM, XRD, and EDS. Factors influencing the adsorption of Cu2+, e.g., initial metal concentration, initial pH, contact time and adsorbent concentration were

Yu-Ting Zhou; Hua-Li Nie; Christopher Branford-White; Zhi-Yan He; Li-Min Zhu

2009-01-01

224

Fabrication of BaFe12O19 Nanowires by a Hydrothermal Process and Their Magnetic Properties  

Microsoft Academic Search

Magnetic BaFe12O19 nanowires have been prepared by a hydrothermal process. The nanowires with diameters ~ 15 nm and lengths ~ 2 mum are clearly visible in Transmission Electron Microscopy (TEM) image. The physical properties of the BaFe12O19 nanowires were further characterized by X-ray diffraction (XRD) and magnetization measurement. The results of the magnetization measurement show that the sample displays ferromagnetic

Jun Wang; Yuejin Zhu

2006-01-01

225

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)

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.

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

2014-04-01

226

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

SciTech Connect

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.

Hesse, Christoph; Goetz-Neunhoeffer, Friedlinde; Neubauer, Juergen, E-mail: neubauer@geol.uni-erlangen.d

2011-01-15

227

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

SciTech Connect

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.

Pham, Thai V.; Fulton, John L.

2013-01-28

228

Magnetic Seesaw  

NSDL National Science Digital Library

In this activity, learners build a seesaw powered by magnets. Use this activity to demonstrate how a lever is a simple machine and how magnets repel and attract depending on the alignment of the poles.

Mission Science Workshop

2013-01-01

229

Magnetic Declination  

NSDL National Science Digital Library

A page with basic information about magnetic declination and how it changes over time. The page includes a calculator to determine the magnetic declination at your location, as well as tools for comparing the current declination to historical declination.

National Geophysical Data Center

230

Planetary magnetism  

NASA Technical Reports Server (NTRS)

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.

Russell, C. T.

1981-01-01

231

Magnetic Fields  

E-print Network

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.

Schöller, Markus

2015-01-01

232

Structural and magnetic properties of chromium doped zinc ferrite  

SciTech Connect

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)

Sebastian, Rintu Mary; Thankachan, Smitha; Xavier, Sheena; Mohammed, E. M., E-mail: emmohammed2005@gmail.com [Research Department of Physics, Maharaja's College, Ernakulam, Kerala (India); Joseph, Shaji [Department of Physic, St. Albert's College, Ernakulam, Kerala (India)

2014-01-28

233

Formation and optical properties of amorphous carbon film having embedded nanoparticles deposited by anodic jet carbon arc technique  

NASA Astrophysics Data System (ADS)

This paper reports the formation and optical properties of amorphous carbon film having embedded nanoparticles deposited by anodic jet carbon arc technique (AJCA). The films deposited have been characterized by x-ray diffraction (XRD), high resolution transmission electron microscope (HRTEM), and scanning electron microscope (SEM) and spectroscopy ellipsometry (SE) measurements. XRD pattern exhibits dominantly an amorphous nature of film. HRTEM investigation shows initially the amorphous structure. However, on closer examination nanoparticles were found to be embedded in the amorphous matrix. The effect of substrate bias and the magnetic field on the optical constants evaluated from SE have been studied. On comparison of deposition condition with and without magnetic field used in growing a-C films there is a change in the values of optical constants.

Tripathi, R. K.; Panwar, O. S.; Kesarwani, Ajay; Kumar, Sushil; Basu, A.

2012-10-01

234

Magnetic Pendulums  

NSDL National Science Digital Library

In this activity and demonstration about electricity and magnetism, learners observe how the current generated when one copper coil swings through a magnetic field starts a second coil swinging. Learners also explore what happens when they change the polarity of the magnet, reverse the coil, or add a clip lead to short-circuit the coils. Use this activity to illustrate how electricity and magnetism interact. The assembly of the electromagnetic swing device takes about an hour.

Exploratorium, The

2011-12-05

235

Magnetism Hunt  

NSDL National Science Digital Library

In this activity about magnetism (page 4 of the PDF), learners will experiment with magnets and different objects to find out that not all metals are attracted to magnets. Even though there are only a few supplies listed, the possibilities are really endless when it comes to what learners can try to attract to the magnet. Learners make predictions and compare their predictions to actual outcomes.

Cosi

2009-01-01

236

Magnetic Storms  

NSDL National Science Digital Library

This is a lesson to introduce the Kp index, a common numerical indicator of magnetic storminess. Learners will access and analyze Kp index plots of magnetic storm strength and determine the relative frequency of stronger versus weaker magnetic storms during years of maximum solar activity. This resource is activity 13 from the Magnetic Mysteries of the Aurora teachers guide. Internet access is required for this activity.

237

Magnetic materials based on iron dispersed in graphitic matrices II. High temperatures and mesophase pitch  

NASA Astrophysics Data System (ADS)

Ferromagnetic materials based on iron incorporated into pitch were synthesized, and characterized by magnetic methods (Faraday), Mössbauer spectroscopy, SEM, and XRD. A graphitic-type structure was observed to form at 350-1650°C. The important role of a mesophase structure of a pitch-precursor in the iron carbonyl absorption and anisotropic structure of the resulting iron containing material was found.

Dyakonov, Alexander J.; Jack McCormick, B.; Kahol, Pawan K.; Hamdeh, Hussein H.

1997-03-01

238

Occluded cobalt species over ZSM-5 matrix: Design, preparation, characterization and magnetic behavior  

SciTech Connect

Co-containing molecular sieves with MFI structure was synthesized by the hydrothermal crystallization method and cobalt was incorporated in it by wet impregnation at different percentages. Thermal post-treatments were applied to Co-ZSM-5: calcination and reduction. X ray diffraction (XRD) and FTIR studies confirmed crystallinity, structure and orthorhombic symmetry of the obtained samples (Co-ZSM-5 calcined and Co-ZSM-5 reduced). The XRD, Raman spectroscopy, SEM and TPR techniques for the calcined samples showed the presence of Co{sub 3}O{sub 4} which diminished in the reduced samples and Co{sup 0} appeared. The magnetic behavior of the materials was evaluated by magnetization (M) variation with applied magnetic field (H) at different temperatures. Low magnetization is observed in the calcined samples while high values are attained in the reduced samples, due to the presence of metallic Co.

Pierella, Liliana B. [Grupo Zeolitas-CITeQ, Centro de Investigacion y Tecnologia Quimica, Facultad Cordoba, Universidad Tecnologica Nacional, Cordoba (Argentina); Conicet, Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina)], E-mail: lpierella@scdt.frc.utn.edu.ar; Saux, Clara [Grupo Zeolitas-CITeQ, Centro de Investigacion y Tecnologia Quimica, Facultad Cordoba, Universidad Tecnologica Nacional, Cordoba (Argentina); Conicet, Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina); Bertorello, Hector R.; Bercoff, Paula G. [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Cordoba (Argentina); Conicet, Consejo Nacional de Investigaciones Cientificas y Tecnicas (Argentina); Botta, Pablo M.; Rivas, J. [Departamento de Fisica Aplicada, Universidad de Santiago de Compostela, Facultad de Fisica, Campus Sur, 15782 Santiago de Compostela (Spain)

2008-08-04

239

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

NASA Astrophysics Data System (ADS)

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.

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

240

Structural and magnetic studies on transition metal (Mn, Co) doped ZnO nanoparticles  

NASA Astrophysics Data System (ADS)

We report on the structural and magnetic properties of the nanocrystalline samples of Zn 1- x(TM) xO (TM=Mn, Co and x=0.02, 0.05, 0.10) synthesized by chemical vapor deposition (CVD) method using different carrier gases i.e., Argon (Ar), Oxygen (O 2) and Nitrogen (N 2). X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies reveal wurtzite structure of pure ZnO in all the samples and particle sizes in the range of 15-40 nm. No evidence of any secondary phases having room temperature ferromagnetic behavior has been observed through XRD and TEM studies. Magnetic measurements reveal presence of mixed magnetic phases in the samples, which may be the reason for the low saturation magnetization in the nanoparticles.

Sharma, V. K.; Najim, M.; Srivastava, A. K.; Varma, G. D.

2012-03-01

241

Magnetic Suction  

NSDL National Science Digital Library

In this activity about electricity and magnetism, learners discover how a doorbell works. A coil of wire with current flowing through it forms an electromagnet that acts similar to a bar magnet. The coil will magnetize an iron nail and attract it in a remarkably vigorous way.

Exploratorium, The

2012-11-13

242

Seeing Magnetism  

NSDL National Science Digital Library

This is lesson to begin learners' thinking about magnetic influence. Learners will watch a classroom demonstration about the effect of magnets on iron filings and then complete a journal assignment to record their reactions and thoughts. This is the first activity in the Mapping Magnetic Influence educators guide.

243

Magnetic properties of nanoscale iron particles  

NASA Astrophysics Data System (ADS)

Nanoscale iron particles have been prepared by iron atom clustering in cold pentane. Particle growth was terminated by adsorption of oleic acid, yielding air stable particles ranging in size from 2 to 12 nm, that were amorphous according to XRD analysis. TEM analysis showed that the larger particles were prolate spheroids while the smaller ones were spherical. The as-prepared sample had a room-temperature saturation magnetization of Ms=12.3 emu/g and a coercivity of Hc=60 Oe. Following heat treatment under argon, the XRD results showed the following reaction scheme; oxidation to Fe3O4 at 360 °C and reduction to ?-Fe at 520 °C (processes apparently due to adsorbed oleic acid). For the 520 °C treated sample, the room-temperature saturation magnetization and coercivity were Ms=200 emu/g and Hc=20 Oe, respectively. By pentane washing of the as-prepared sample, the smaller particles could be separated by filtration leaving the larger 8-12 nm particles on the filter. This powdered sample trapped on the filter had Ms=54.9 emu/g and Hc=60 Oe. Heat treatment of this sample also caused oxidation to Fe3O4 at 360 °C and an incomplete reduction to ?-Fe and FeO at 520 °C. For the 520 °C treated sample, the recorded room-temperature saturation magnetization and coercivity were Ms=123.6 emu/g and Hc=20 Oe, respectively.

Kerznizan, Carl F.; Klabunde, Kenneth J.; Sorensen, Christopher M.; Hadjipanayis, George C.

1990-05-01

244

Preparation and Properties of Various Magnetic Nanoparticles  

PubMed Central

The fabrications of iron oxides nanoparticles using co-precipitation and gadolinium nanoparticles using water in oil microemulsion method are reported in this paper. Results of detailed phase analysis by XRD and Mössbauer spectroscopy are discussed. XRD analysis revealed that the crystallite size (mean coherence length) of iron oxides (mainly ?-Fe2O3) in the Fe2O3 sample was 30 nm, while in Fe2O3/SiO2 where the ?-Fe2O3 phase dominated it was only 14 nm. Gd/SiO2 nanoparticles were found to be completely amorphous, according to XRD. The samples showed various shapes of hysteresis loops and different coercivities. Differences in the saturation magnetization (MS) correspond to the chemical and phase composition of the sample materials. However, we observed that MS was not reached in the case of Fe2O3/SiO2, while for Gd/SiO2 sample the MS value was extremely low. Therefore we conclude that only unmodified Fe2O3 nanoparticles are suitable for intended biosensing application in vitro (e.g. detection of viral nucleic acids) and the phase purification of this sample for this purpose is not necessary. PMID:22574017

Drbohlavova, Jana; Hrdy, Radim; Adam, Vojtech; Kizek, Rene; Schneeweiss, Oldrich; Hubalek, Jaromir

2009-01-01

245

Formation, structure and magnetic properties of GdFe 11Re  

Microsoft Academic Search

The structural and magnetic properties of the ternary GdFe11Re compound were investigated by means of X-ray diffraction analysis and magnetic measurement. GdFe11Re crystallizes in a tetragonal structure with space group I4\\/mmm. The lattice parameters are a=8.5339 Å and c=4.7603 Å. The results of Rietveld refinement of powder XRD data revealed that the Re atoms preferentially occupy the 8i site. This

W. G Chu; G. H Rao; H. F Yang; G. Y Liu; J. K Liang

2002-01-01

246

Simulated solar-light assisted photocatalytic ozonation of metoprolol over titania-coated magnetic activated carbon  

Microsoft Academic Search

A magnetically separable photocatalyst consisting of magnetic porous activated carbon with attached anatase TiO2 particles has been prepared and tested for the degradation of metoprolol (MTP) in aqueous solution. The synthesized photocatalyst (TiFeC) was characterized by nitrogen adsorption, XRD, FTIR, SEM, EDX and SQUID magnetometer. The obtained catalyst with a TiO2 composition of 61wt.% (mostly anatase) had moderate surface area

Ana Rey; Diego H. Quiñones; Pedro M. Álvarez; Fernando J. Beltrán; Pawel K. Plucinski

247

Preparation and characterization of carboxyl functionalization of chitosan derivative magnetic nanoparticles  

Microsoft Academic Search

The functionalized magnetic Fe3O4-chitosan derivative nanoparticles have been prepared by the covalent binding of alpha-ketoglutaric acid chitosan (KCTS) onto the surface of Fe3O4 magnetic nanoparticles via carbodiimide activation. Transmission electron microscopy (TEM) showed that the KCTS-bound Fe3O4 nanoparticles were regular spheres with a mean diameter of 26nm. X-ray diffraction (XRD) patterns indicated that the Fe3O4 nanoparticles were pure Fe3O4 with

Gui-yin Li; Ke-long Huang; Yu-ren Jiang; Ping Ding; Dong-liang Yang

2008-01-01

248

Preparation and properties of magnetic Fe 3O 4–chitosan nanoparticles  

Microsoft Academic Search

Magnetic Fe3O4–chitosan nanoparticles were prepared by the covalent binding of chitosan (CTS) onto the surface of magnetic Fe3O4 nanoparticles which were prepared by hydrothermal method using H2O2 as an oxidizer. Transmission electron microscopy (TEM) showed that Fe3O4 particles and Fe3O4–chitosan nanocomposites were regular sphere with a mean diameter of 23nm and 25nm, respectively. X-ray diffraction patterns (XRD) indicated that the

Gui-yin Li; Yu-ren Jiang; Ke-long Huang; Ping Ding; Jie Chen

2008-01-01

249

Effects of boron-doping on the morphology and magnetic property of carbon nanotubes  

Microsoft Academic Search

Boron carbide nanotubes (nano-fibers) was prepared by B powder and carbon nanotubes (CNTs) at high temperature in a vacuumed\\u000a quartz tube. The morphology, microstructure, component and magnetic property of samples were characterized by transmission\\u000a electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and magnetic property measurement\\u000a system (MPMS) controller. The results showed that B-doping CNTs have great difference

Qi Jiang; Lan Qian; Jing Yi; Xiaotong Zhu; Yong Zhao

2007-01-01

250

Study of room temperature ferromagnetism for cobalt and manganese doped ZnO diluted magnetic semiconductor  

Microsoft Academic Search

We report the results of electronic and magnetic properties of poly-crystalline Zn1-xMxO (M = Co and Mn) pellets studied by XRD, VSM and XPS. The specimens were synthesized by solid state reaction method using high purity oxides. Samples exhibit Wurtzite hexagonal symmetry and show interesting magnetic properties. The Co (5%) doped sample prepared by heating in air shows a paramagnetic

R. K. Singhal; Arvind Samariya; Y. T. Xing; S. N. Dolia; Sudhish Kumar; U. P. Deshpande; T. Shripathi; Elisa Saitovitch

2010-01-01

251

Intrinsic ferromagnetic properties in Cr-doped ZnO diluted magnetic semiconductors  

Microsoft Academic Search

The Cr-doped zinc oxide (Zn1?xCrxO, 0?x?0.08) diluted magnetic semiconductors have been synthesized successfully by the sol–gel method. Investigations on magnetic, optical and structural properties of the produced samples have been done. Energy dispersive spectroscopy (EDS) shows the existence of Cr ion in the Cr-doped ZnO. The results of X-ray diffraction (XRD), the transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS)

Yang Liu; Yanting Yang; Jinghai Yang; Qingfeng Guan; Huilian Liu; Lili Yang; Yongjun Zhang; Yaxin Wang; Maobin Wei; Xiaoyan Liu; Lianhua Fei; Xin Cheng

2011-01-01

252

Electronic and magnetic properties of highly ordered Sr2FeMoO6  

Microsoft Academic Search

The electronic and magnetic properties of the colossal magneto resistance (CMR) compound Sr2FeMoO6 have been studied using different experimental techniques, namely X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS). Furthermore, the magnetic properties have been studied in the temperature range of 4.2 K-800 K. The data confirm a highly ordered double perovskite crystal structure and is

K. Kuepper; I. Balasz; H. Hesse; A. Winiarski; K. C. Prince; M. Matteucci; D. Wett; R. Szargan; E. Burzo; M. Neumann

2004-01-01

253

Temperature-Dependent Magnetic Properties of Bismuth Substituted Terbium–Iron Garnets  

Microsoft Academic Search

The crystallographic structure and magnetic properties of bismuth substituted terbium-iron garnets have been studied using X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and Mossbauer spectroscopy. The crystal structures were found to be a cubic garnet structure with space group Ia3d. The lattice constants increase linearly with increasing bismuth concentration. The field-cooled magnetization curves measured at various external fields. The compensation

Il Jin Park; Kun Uk Kang; Chul Sung Kim

2006-01-01

254

Synthesis, characterization and magnetic properties of carbon nanotubes decorated with magnetic MIIFe2O4 nanoparticles  

NASA Astrophysics Data System (ADS)

In this study, a simple, efficient and reproducible microemulsion method was applied for the successful decoration of carbon nanotubes (CNTs) with magnetic MIIFe2O4 (M = Co, Ni, Cu, Zn) nanoparticles. The structure, composition and morphology of the prepared nanocomposite materials were characterized using X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). The magnetic properties were investigated by the vibrating sample magnetometer (VSM). The SEM results illustrated that large quantity of MIIFe2O4 nanoparticles were uniformly decorated around the circumference of CNTs and the sizes of the nanoparticles ranged from 15 to 20 nm. Magnetic hysteresis loop measurements revealed that all the MIIFe2O4/CNTs nanocomposites displayed ferromagnetic behavior at 300 K and can be manipulated using an external magnetic field. The CoFe2O4/CNTs nanocomposite showed maximum value of saturation magnetization which was 37.47 emu g-1. The as prepared MIIFe2O4/CNTs nanocomposites have many potential application in magnetically guided targeted drug delivery, clinical diagnosis, electrochemical biosensing, magnetic data storage and magnetic resonance imaging.

Ali, Syed Danish; Hussain, Syed Tajammul; Gilani, Syeda Rubina

2013-04-01

255

Induced size effect on Ni doped Nickel Zinc Ferrite Nanoparticles  

Microsoft Academic Search

Nickel zinc ferrite (NixZn1?xFe2O4 where x=0.1, 0.3, 0.5) nanoparticles were synthesized by chemical co-precipitation method. The doping effect of nickel ions on crystalline phase, size, particle size, and saturation magnetization (M S) are investigated. The XRD patterns confirm the single crystalline phase of the nanoparticles. The lattice parameter decreases with increase in Ni content and reduces lattice strain. HRTEM images

Ashok Kumar; Annveer; Manju Arora; M. S. Yadav; R. P. Panta

2010-01-01

256

Superconducting Magnet Division Magnet Note  

E-print Network

and is based on commercially available High Temperature Superconductors (HTS). The magnet will operate at ~30 K of the Magnetic Mirror Model of the HTS RIA Quadrupole S. OzakiM. Anerella B. ParkerJ. Cozzolino S. PeggsW. Louie E. WillenJ. Muratore #12;Construction and Test of the Magnetic Mirror Model of the HTS RIA

Gupta, Ramesh

257

Electroplating hard magnetic SmCo for magnetic microactuator applications  

SciTech Connect

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.

Chen Jue; Rissing, Lutz [Institute for Micro Production Technology, Center for Production Technology, Leibniz Universitaet Hannover, An der Universitaet 2, 30823 Garbsen (Germany)

2011-04-01

258

Structural Changes and Thermal Stability of Charged LiNixMnyCozO2 Cathode Materials Studied by Combined In Situ Time-Resolved XRD and Mass Spectroscopy.  

PubMed

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 oxygen 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. 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. PMID:25420188

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

2014-12-24

259

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

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.

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

2014-05-05

260

The effects of high magnetic field on the morphology and microwave electromagnetic properties of MnO 2 powder  

NASA Astrophysics Data System (ADS)

MnO 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.

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

2010-07-01

261

Mössbauer spectroscopy studies of carbon-encapsulated magnetic nanoparticles obtained by different routes  

NASA Astrophysics Data System (ADS)

Carbon-encapsulated magnetic nanoparticles (CEMNPs) are nanomaterials with a core-shell structure. Their intrinsic properties result both from the unique nature of the encapsulated magnetic phases and the high chemical stability of the external carbon shells. CEMNPs may find many prospective applications, e.g., in magnetic data storage, catalysis, xerography, magnetic resonance imaging, and in biomedical applications. Herein, we present detailed structural studies of such nanostructures by Mössbauer spectroscopy, x-ray diffraction (XRD), scanning electron microscopy, and transmission electron microscopy. CEMNPs have been obtained by three different techniques: carbon arc, combustion synthesis, and radio frequency thermal plasma. The evaluation of the phase composition of the products was strongly limited due to the broadening and overlapping of the lines in XRD diffraction patterns. The presence of the semicrystalline phases, which could not been identified by XRD, was established by Mössbauer spectroscopy. Furthermore, the magnetic core phase composition was evaluated quantitatively. The products were purified before structural analyses to remove the nonencapsulated particles. The purification caused significant changes in the mass and the saturation magnetization. The Mössbauer spectra of the purified products were compared with the literature data concerning the as-produced CEMNPs.

Bystrzejewski, M.; Grabias, A.; Borysiuk, J.; Huczko, A.; Lange, H.

2008-09-01

262

Magnetic investigations  

SciTech Connect

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.

Bath, G.D.; Jahren, C.E.; Rosenbaum, J.G. [Geological Survey, Denver, CO (USA); Baldwin, M.J. [Fenix and Scisson, Inc., Mercury, NV (USA)

1983-12-31

263

Synthesis, spectral, stereochemical, single crystal XRD and biological studies of 3t-pentyl-2r,6c-diarylpiperidin-4-one picrate derivatives  

NASA Astrophysics Data System (ADS)

Various substituted 3t-pentyl-2r,6c-diphenylpiperidin-4-one picrates (1-7) were synthesised and characterised by elemental analysis, FT-IR and NMR spectral studies. NMR spectral assignments were made unambiguously by their one dimensional (1H NMR and 13C NMR) and two dimensional (1H-1H COSY, HSQC, HMBC, NOESY, DEPT) NMR spectra. Single crystal XRD analysis of the compound (1) has confirmed that the complex crystallized in monoclinic system with P21/n space group. The difference in the chemical shifts between equatorial methylene proton and axial proton at C(5) [? = ?eq - ?ax] is highly negative in compounds 1-7 in contrast to the value observed for the corresponding parent piperidine-4-one and is indicative of the 1,3-diaxial interaction between the axial NH bond and axial hydrogen at C(5). The chemical shifts of the heterocyclic ring protons are influenced by the picrate anion. All the synthesised compounds exhibited good activity against S. aureus-Staphylococcus aureus bacterial strains and C. albicans fungal strains.

Savithiri, S.; Arockia doss, M.; Rajarajan, G.; Thanikachalam, V.

2014-10-01

264

Characterisation of mineralogical forms of barium and trace heavy metal impurities in commercial barytes by EPMA, XRD and ICP-MS.  

PubMed

This study was carried out to characterise the mineralogical forms of barium and the trace heavy metal impurities in commercial barytes of different origins using electron probe microanalysis (EPMA), X-ray diffraction (XRD) and inductively coupled plasma mass spectrometry (ICP-MS). Qualitative EPMA results show the presence of typically eight different minerals in commercial barytes including barite (BaSO4), barium feldspar, galena (PbS), pyrite (FeS2), sphalerite (ZnS), quartz (SiO2), and silicates, etc. Quantitative EPMA confirms that the barite crystals in the barytes contain some strontium and a little calcium, whereas trace heavy metals occur in the associated minerals. Analysis of aqua regia extracts of barytes samples by ICP-MS has shown the presence of a large number of elements in the associated minerals. Arsenic, copper and zinc concentrations correlate closely in all 10 samples. The findings suggest that barytes is not, as traditionally thought, an inert mineral, but is a potentially toxic substance due to its associated heavy metal impurities, which can be determined by an aqua regia digest without the need for complete dissolution of the barite itself. X-ray powder diffraction was not informative as the complex barite pattern masks the very weak lines from the small amounts of associated minerals. PMID:11253006

Ansari, T M; Marr, I L; Coats, A M

2001-02-01

265

Synthesis, molecular structure, FT-IR and XRD investigations of 2-(4-chlorophenyl)-2-oxoethyl 2-chlorobenzoate: a comparative DFT study.  

PubMed

2-(4-Chlorophenyl)-2-oxoethyl 2-chlorobenzoate has been synthesized, its structural and vibrational properties have been reported using FT-IR and single-crystal X-ray diffraction (XRD) studies. The conformational analysis, optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of the synthesized compound (C15H10Cl2O3) have been examined by means of Becke-3-Lee-Yang-Parr (B3LYP) density functional theory (DFT) method together with 6-31++G(d,p) basis set. Furthermore, reliable conformational investigation and vibrational assignments have been made by the potential energy surface (PES) and potential energy distribution (PED) analyses, respectively. Calculations are performed with two possible conformations. The title compound crystallizes in orthorhombic space group Pbca with the unit cell dimensions a=12.312(5) Å, b=8.103(3) Å, c=27.565(11) Å, V=2750.0(19) Å(3). B3LYP method provides satisfactory evidence for the prediction of vibrational wavenumbers and structural parameters. PMID:24509537

Chidan Kumar, C S; Fun, Hoong Kun; Tursun, Mahir; Ooi, Chin Wei; Chandraju, Siddegowda; Quah, Ching Kheng; Parlak, Cemal

2014-04-24

266

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

PubMed

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

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

2014-01-24

267

Composition-dependent structure of polycrystalline magnetron-sputtered V–Al–C–N hard coatings studied by XRD, XPS, XANES and EXAFS  

PubMed Central

V–Al–C–N hard coatings with high carbon content were deposited by reactive radio-frequency magnetron sputtering using an experimental combinatorial approach, deposition from a segmented sputter target. The composition-dependent coexisting phases within the coating were analysed using the complementary methods of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption near-edge spectroscopy (XANES) and extended X-ray absorption fine-structure spectroscopy (EXAFS). For the analysis of the X-ray absorption near-edge spectra, a new approach for evaluation of the pre-edge peak was developed, taking into account the self-absorption effects in thin films. Within the studied composition range, a mixed face-centred cubic (V,Al)(C,N) phase coexisting with a C–C-containing phase was observed. No indication of hexagonal (V,Al)(N,C) was found. The example of V–Al–C–N demonstrates how important a combination of complementary methods is for the detection of coexisting phases in complex multi-element coatings. PMID:24046506

Krause, Bärbel; Darma, Susan; Kaufholz, Marthe; Mangold, Stefan; Doyle, Stephen; Ulrich, Sven; Leiste, Harald; Stüber, Michael; Baumbach, Tilo

2013-01-01

268

Magnetic and dielectric properties of Ba12Fe28Ti15O84 layered ferrite ceramics  

NASA Astrophysics Data System (ADS)

In this study we report for the first time the magnetic and dielectric properties of the quaternary layered ferrite Ba12Fe28Ti15O84. Dense ferrite ceramics were prepared by conventional sintering using powders obtained by solid-state reaction and by coprecipitation. Only the latter powder resulted in nearly single phase ceramics, whereas larger amounts of secondary phases were observed in the material obtained by the solid-state route. According to the HRTEM investigation, the ferrite lattice is originated by the intergrowth of perovskite-like and spinel-like slabs and can be considered as a natural magnetic superlattice. A ferrimagnetic order with saturation magnetization of ?12.5 A m2 kg-1 and coercivity of ~1590 A m-1 (~20 Oe) is proposed at room temperature. The thermomagnetic data indicate a Curie temperature of ~420 K for the quaternary ferrite. An additional magnetic transition was detected at ~700 K and ascribed to a secondary magnetic phase, probably the solid solution of TiO2 in BaFe12O19. An intrinsic relative dielectric constant of the order of 23-50 at room temperature was measured at 109 Hz. At lower frequency the dielectric behaviour is dominated by extrinsic effects related to the heterogeneous electrical nature of the ceramics corresponding to semiconducting grains separated by more insulating grain boundary regions. The dielectric losses are rather high, often >1, indicating an overall semiconducting character of the material.

Curecheriu, L. P.; Buscaglia, M. T.; Ianculescu, A. C.; Frunza, R. C.; Ciuchi, I. V.; Neagu, A.; Apachitei, G.; Bassano, A.; Canu, G.; Postolache, P.; Mitoseriu, L.; Buscaglia, V.

2011-11-01

269

Temperature-dependent magnetization in (Mn, N)-codoped ZnO-based diluted magnetic semiconductors  

NASA Astrophysics Data System (ADS)

The influences of Mn doping on the structural quality of the ZnxMn1-xO:N alloy films have been investigated by XRD. Chemical compositions of the samples (Zn and Mn content) and their valence states were determined by X-ray photoelectron spectrometry (XPS). Hall effect measurements versus temperature for ZnxMn1-xO:N samples have been designed and studied in detail. The ferromagnetic transitions happened at different TC should explain that the magnetic transition in field-cooled magnetization of Zn1-xMnxO:N films at low temperature is caused by the strong p-d exchange interactions besides magnetic transition at 46 K resulting from Mn oxide, and that the room temperature ferromagnetic signatures are attributed to the uncompensated spins at the surface of anti-ferromagnetic nano-crystal of Mn-related Zn(Mn)O.

Wu, Kongping; Gu, Shulin; Tang, Kun; Ye, Jiandong; Zhu, Shunming; Zhou, Mengran; Huang, Yourui; Xu, Mingxiang; Zhang, Rong; Zheng, Youdou

2012-04-01

270

Magnetic properties of graphite oxide and reduced graphene oxide  

NASA Astrophysics Data System (ADS)

Graphite oxide (GO) and reduced graphene oxide (RGO) have been prepared using standard chemical methods. The formations of the oxides are characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) studies. Both the oxides exhibit weak superparamagnetism and hysteresis for the first time at room temperature. Magnetic moment for RGO is comparatively smaller than that of GO sample. The superparamagnetism in these oxides is attributed to the presence of single domains, each domain being cluster of defect induced magnetic moments coupled by ferromagnetic interaction. Apart from these single domain clusters there are other defect induced moments coupled by ferromagnetic interaction which show ferromagnetism and hysteresis.

Sarkar, S. K.; Raul, K. K.; Pradhan, S. S.; Basu, S.; Nayak, A.

2014-11-01

271

Magnetic Fluids  

NSDL National Science Digital Library

In this fun, engaging activity, students are introduced to a unique type of fluid—ferrofluids—whose shape can be influenced by magnetic fields! Students act as materials engineers and create their own ferrofluids. They are challenged to make magnetic ink out of ferrofluids and test their creations to see if they work. Concurrently, they learn more about magnetism, surfactants and nanotechnology. As they observe fluid properties as a standalone-fluid and under an imposed magnetic field, they come to understand the components of ferrofluids and their functionality.

National Science Foundation GK-12 and Research Experience for Teachers (RET) Programs,

272

Strange Magnetism  

E-print Network

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.

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

1998-11-09

273

Planetary magnetism  

NASA Technical Reports Server (NTRS)

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.

Russell, C. T.

1980-01-01

274

Magnetic fabrics  

NASA Astrophysics Data System (ADS)

Since Graham [1954; 1967] demonstrated in the 1950s and 1960s that magnetic anisotropy was a quick and non-destructive way of measuring rock fabric, magnetic fabric measurements have become increasingly prevalent in the study of earth and environmental processes (see Table 1 for definitions of magnetic terms). The accomplishments of U.S. workers over the past 4 years show that the U.S. community continues to contribute to the growth and development of the field. In addition to the more traditional anisotropy of magnetic susceptibility (AMS) measurements work is branching out to include anisotropy of remanence studies, particularly anisotropy of anhysteretic remanence (AAR) [McCabe et al, 1985] and anisotropy of isothermal remanence (AIR), since these parameters can be tied directly to the remanence-carrying grains in a rock and hence have relevance to the effects of magnetic fabric on natural remanent magnetization (NRM). Along with this shift is the realization, as a result of combining nonmagnetic observations (e.g.. scanning electron microscopy (SEM), finite strain measurements) with rock magnetic measurements (e.g.. hysteresis parameters), that magnetic mineral composition (paramagnetic and ferromagnetic) has an important control on magnetic anisotropy.

Kodama, Kenneth P.

1995-07-01

275

Magnetic Field Safety Magnetic Field Safety  

E-print Network

Magnetic Field Safety Training #12;Magnetic Field Safety Strong Magnetic Fields exist around energized magnets. High magnetic fields alone are a recognized hazard only for personnel with certain medical conditions such as pacemakers, magnetic implants, or embedded shrapnel. In addition, high magnetic

McQuade, D. Tyler

276

Preparation and characterization of magnetic levan particles as matrix for trypsin immobilization  

NASA Astrophysics Data System (ADS)

Magnetic levan was synthesized by co-precipitating D-fructofuranosyl homopolysaccharide with a solution containing Fe2+ and Fe3+ in alkaline conditions at 100 °C. The magnetic levan particles were characterized by scanning electron microscopy (SEM), magnetization measurements, X-ray diffractometry (XRD) and infrared spectroscopy (IR). Afterwards, magnetic levan particles were functionalized by NaIO4 oxidation and used as matrices for trypsin covalent immobilization. Magnetite and magnetic levan particles were both heterogeneous in shape and levan-magnetite presented bigger sizes compared to magnetite according to SEM images. Magnetic levan particles exhibited a magnetization 10 times lower as compared to magnetite ones, probably, due to the coating layer. XRD diffractogram showed that magnetite is the dominant phase in the magnetic levan. Infrared spectroscopy showed characteristics absorption bands of levan and magnetite (O-H, C-O-C and Fe-O bonds). The immobilized trypsin derivative was reused 10 times and lost 16% of its initial specific activity only. Therefore, these magnetic levan particles can be proposed as an alternative matrices for enzyme immobilization.

Maciel, J. C.; Andrad, P. L.; Neri, D. F. M.; Carvalho, L. B.; Cardoso, C. A.; Calazans, G. M. T.; Albino Aguiar, J.; Silva, M. P. C.

2012-04-01

277

Magnetic mineralogy of heavy metals-contaminated soils  

NASA Astrophysics Data System (ADS)

Soils around mine and in urban areas are often contaminated by heavy metals derived from industrial and human activities [1, 2]. These contaminated soils are often characterized by a magnetic enhancement on topsoils. Many studies demonstrated that there are significant correlations between heavy metals and various magnetic parameters in contaminated soils, indicating a strong affinity of heavy metals to magnetic minerals. The magnetic particles in contaminated soils were separated by a magnetic separation technique. The rock magnetism, XRD, field emission scanning electron microscopy equiped with an energy-dispersive X-ray analyzer (FESEM/EDX) were used to characterize their magnetic mineralogy. Results of XRD analysis indicated that the magnetic particles separated from heavy metal-contaminated soils are composed of quartz, magnetite, and hematite. Based on the X-ray diffraction peak intensity, the Fe3O4 was identified as the predominant magnetic mineral phase. The high-temperature magnetization (Ms-T) curves of magnetic particles extracted from contaminated soils show a sharp Ms decrease at about 580C (the Curie temperature of magnetite), suggesting that magnetite is the dominant magnetic carrier. The hysteresis loops of contaminated soils are closed at about 100-200 mT which is consistent with the presence of a dominant ferrimagnetic mineral phase. The FESEM analysis showed a great variety of shapes of magnetic particles in contaminated soils. The most common morphology are observed in the form of spherules, with the sizes ranging from 20 to 100 um. The chemical composition of magnetic particles consist mainly of Fe, Si, Al, and Ca with minor heavy metal elements (Cu, Zn, Hg, and Cr). The semi-quantitative Fe content identified by FESEM/EDX ranged from 40 to 90%. Combined studies of rock magnetism, XRD, and FESEM/EDX indicated that magnetic mineral phases responsible for the magnetic enhancement of contaminated soils are anthropogenic origin which are coarse-grained multi-domain (MD) ferrimagnetic minerals. These spherical magnetic particles in contaminated soils are most likely related to airborne particles from coal combusition and industrial activities. Coal burning, metallurgical and industrial dusts contain a significant fraction of ferrimagnetic minerals. The magnetic particles in fly ash from coal-burning power plant have a typical spherical morphology, ranging from 10 to 100 ?m. Vehicle emissions have been suggested to be another source of magnetic particles. These anthropogenic ferrimagnetic mineral phases are directly responsible for the magnetic enhancement in the contaminated soils. Therefore, the strong magnetic signature in contaminated soils can be used as an effective tool for identifying pollution sources and quantifying pollution level of heavy metals. Acknowledgements: This research was supported by National Nature Science Foundation of China (No. 41171182 and 40971131) and the Ph.D. Programs Foundation of Ministry of Education of China (20090101110088). [1] Lu, S.G. & Bai, S.Q. (2006) J. Appl. Geophys., 60, 1-12. [2] Lu, S.G., Bai, S.Q. & Xue, Q.F. (2007) Geophys. J. Inter., 171, 568-580.

Shenggao, L.

2012-04-01

278

XRD line-broadening characteristics of M-oxides (M = Mg, Mg-Al, Y, Fe) nanoparticles produced by coprecipitation method  

SciTech Connect

Simple coprecipitation method has been used to produce nanoparticles of MgO (magnesia), MgO{center_dot}Al{sub 2}O{sub 3}(spinel), Y{sub 2}O{sub 3}(yttria) and Fe{sub 3}O{sub 4}(ferrite). The raw materials were, in respective, magnesium powder, magnesium and aluminium powders, ytrria powder, and natural sand. The coprecipitation included the use of suitable acid and base to dissolve the powders or sand and to produce precipitates, as well as the use of water to wash and purify the precipitates, and drying at relatively low temperatures, namely lower than 100 deg. C, followed by heating at 450 deg. C, 750 deg. C, 600 deg. C and 200 deg. C to produce magnesia, spinel, yttria and ferrite nanopowders, respectively. X-ray diffractometry was used to characterise the purity and nanocrystallinity of the final powders. It was found qualitatively that the powders were of high purity. Further line-broadening analysis using single-line and Rietveld-based softwares was performed to reveal the nanocrystallinity of the powders. Different line breadth values were found for the powders, indicating different crystallite sizes. It was also found that, particularly for spinel and yttria, the diffraction peaks exhibited 'longer' tails, indicating broader crystallite size distribution. The average crystallite size for the powders ranged from 3 to 70 nm. The results could then be used as 'fingerprints' for nanocrystallinity using x-ray diffractometry. The XRD crystallite sizes for yttria and ferrite nanocrystals are in fair agreement with their counterparts from electron microscopy observation.

Pratapa, S.; Susanti, L.; Insany, Y. A. S.; Alfiati, Z.; Hartono, B.; Mashuri,; Triwikantoro; Baqiya, M. A.; Purwaningsih, S.; Yahya, E.; Darminto [Department of Physics, Institute of Technology Sepuluh November (ITS), Jl. Arief Rahman Hakim, Surabaya, Indonesia 60111 (Indonesia); Taufiq, Ahmad; Fuad, Abdullah [Department of Physics, State University of Malang, Jl. Surabaya, Malang, Indonesia 60111 (Indonesia)

2010-10-24

279

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

PubMed

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

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

2014-03-01

280

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

NASA Astrophysics Data System (ADS)

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).

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

2015-01-01

281

One-pot solvothermal syntheses and magnetic properties of graphene-based magnetic nanocomposites  

Microsoft Academic Search

In this study, graphene-based magnetic nanocomposites (graphene\\/Fe3O4 and graphene oxide\\/Fe3O4) have been prepared via a facile and effective one-pot solvothermal method. X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy and ultraviolet–visible (UV–vis) spectroscopy were used to demonstrate the successful attachment of Fe3O4 nanoparticles to graphene and graphene oxide sheets. It is shown that the Fe3O4 nanoparticles

Xiaoping Shen; Jili Wu; Song Bai; Hu Zhou

2010-01-01

282

Magnetic Fields  

NSDL National Science Digital Library

This page and its annex describes, in trivial terms, the physics of magnetic fields and the history of its discovery. Included is the work of Halley, Oersted, Ampere and Maxwell. It also describes a way of demonstrating it in the classroom, using a vu-graph projector. Later sections #5, #5a and #6 extend this to magnetic field lines and electromagnetism.

Stern, David

2005-01-04

283

Magnetic shielding  

DOEpatents

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.

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

1985-02-12

284

Magnetic Materials  

NSDL National Science Digital Library

Students begin working on the grand challenge of the unit by thinking about the nature of metals and quick, cost-effective means of separating different metals, especially steel. They arrive at the idea, with the help of input from relevant sources, to use magnets, but first they must determine if the magnets can indeed isolate only the steel.

Vu Bioengineering Ret Program

285

Magnetic behavior of nanocrystalline MnCo 2O 4 spinels  

NASA Astrophysics Data System (ADS)

A series of powders with different particle sizes of the spinel MnCo2O4 was synthesized by the Pechini method. The resulting precursor was calcined between 400 and 900C and characterized by thermogravimetric analyses (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and magnetization measurements. TGA analysis showed a loss of mass in the region from 200 to 650C and stability after this. XRD patterns showed an increase of the crystallite size with calcination temperature. Magnetization measurements on the sample calcined at 900C showed an unusual behavior of the hysteresis curve and irreversibility of the magnetization with field cooled (FC) and zero field cooled (ZFC) procedures. An evolution of this behavior was observed with increasing crystallite size.

Borges, F. M. M.; Melo, D. M. A.; Câmara, M. S. A.; Martinelli, A. E.; Soares, J. M.; de Araújo, J. H.; Cabral, F. A. O.

2006-07-01

286

Preparation, structure and magnetic characterization of Ni doped ZnO nano-particles  

NASA Astrophysics Data System (ADS)

The nature of magnetism in Ni-doped ZnO magnetic nano-particles (x=0.0, 0.10, 0.15, 0.20, 0.30) are synthesized by the sol-gel technique using solutions of Ni and Zn based alkoxide which are dissolved into a solvent and a chelating agent. X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and Vibrating Sample Magnetometer (VSM) were employed to understand how the Ni-doped influenced the structural and magnetic properties of the nano-crystalline ZnO particles. The grain sizes of the ZnNiO nano-particles were measured to be approximately 90 nm by means of a Scanning Electron Microscope. XRD measurements and SEM studies show that Ni-doped ZnO has wurtzite structures with NiO secondary phases. Room temperature ferromagnetism was observed for highly Ni-doped ZnO nano-particles.

Do?an, N.; Bingölbali, A.; Arda, L.

2015-01-01

287

Grain Size Control of the Magnetic Nanoparticles by Solid State Route Modification  

NASA Astrophysics Data System (ADS)

The CoFe2O4 and NiFe2O4 nanoparticles were synthesized exploiting a co-precipitation method and afterward calcinated at 400 °C through two different experimental apparatus: a conventional muffle and rotatory oven. X-ray diffraction (XRD) analysis revealed that nanocrystalline ferrites grew with a face center cubic structure (fcc) and Fd3 m symmetry space group. XRD, transmission electron microscopy, and magnetic measurements confirmed the compositional homogeneity and the narrow size particle distribution (6-8 nm) of the sample thermally treated in a rotary oven, in all likelihood due to the sample's constant turning movement. The size of the magnetic particles is extremely important and influences the choice of a potential technological application. For this reason, our study emerges as a new and simple innovating procedure to control the size of magnetic nanoparticles.

Barreto, A. C. H.; Santiago, V. R.; Freire, R. M.; Mazzetto, S. E.; Sasaki, J. M.; Vasconcelos, I. F.; Denardin, J. C.; Mele, Giuseppe; Carbone, Luigi; Fechine, P. B. A.

2013-07-01

288

Structural and magnetic properties of TM-SiO2 (TM = Fe, Co, Ni) films  

NASA Astrophysics Data System (ADS)

TMx-(SiO2)1-x (TM=Fe, Co, Ni) thin films were prepared in a wide concentration range (0.35 ?x?1). Structure was studied with transmission electron microscopy (TEM), X-ray diffraction (XRD) and small angle X-ray scattering (SAXS). Magnetic and magnetotransport properties were investigated by means of magnetization and Hall effect measurements. TEM images display nanometric spherical structures embedded in a SiO2 amorphous matrix, with typical sizes increasing from 3 to 5nm when TM volume concentration x is increased. SAXS measurements indicate a complex structure formed by nanosized objects. XRD measurements show that the structure is composed by amorphous SiO2 and TM crystallites. Slightly above the percolation threshold all samples display giant Hall effect. The observed magnetic properties are dependent on x, and display an evolution resulting from the progressive increase of the mean particle size.

Socolovsky, L. M.; Denardin, J. C.; Brandl, A. L.; Knobel, M.; Zhang, X. X.

2003-05-01

289

Magnetic nanotubes  

DOEpatents

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.

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

2010-11-16

290

Development of an x-ray diffraction camera used in magnetic fields up to 10 T  

SciTech Connect

A high-field x-ray diffraction (HF-XRD) camera was developed to observe structural changes of magnetic materials in magnetic fields up to 10 T. The instrument mainly consists of a Debye-Scherrer-type camera with a diameter of 80.1 mm, a 10-T cryocooled superconducting magnet with a 100-mm room-temperature bore, an x-ray source, a power supply, and a chiller for the x-ray source. An x-ray detector (image plate) in the HF-XRD camera can be taken out and inserted into the magnet without changing the sample position. The performance of the instrument was tested by measuring the HF-XRD for silicon and ferromagnetic MnBi powders. A change of x-ray diffraction pattern was observed due to the magnetic orientation of MnBi, showing that the instrument is useful for studying field-induced orientation processes and structural properties of field-controlled materials.

Mitsui, Yoshifuru; Takahashi, Kohki; Watanabe, Kazuo [High Field Laboratory for Superconducting Materials, Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Koyama, Keiichi [High Field Laboratory for Superconducting Materials, Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Graduate School for Science and Engineering, Kagoshima University, Kagoshima 890-0065 (Japan)

2011-12-15

291

Synthesis and Characterization of CoFe2O4\\/Ni0.5Zn0.5Fe2O4 Core\\/shell Magnetic Nanocomposite by the Wet Chemical Route  

Microsoft Academic Search

A cobalt ferrite\\/nickel-zinc ferrite core\\/shell nanocomposite was synthesized by a polymerized complex method using iron citrate, cobalt nitrate, nickel nitrate, zinc nitrate, citric acid, ethylene glycol, benzoic acid and sodium citrate as starting materials. The XRD, TEM and VSM techniques were employed to evaluate the phase composition, morphology and magnetic properties of the samples. The XRD results indicated the coexistence

A. Honarbakhsh-Raouf; H. R. Emamian; A. Yourdkhani; A. Ataie

2010-01-01

292

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...

293

2806 IEEE TRANSACTIONS ON MAGNETICS, VOL. 39, NO. 5, SEPTEMBER 2003 Interfacial Composition and Microstructure of Fe3O4  

E-print Network

MnSb), chromium dioxide (CrO ), Pervoskites (La Sr MnO ), and magnetite (Fe O ) are expected to be half and magnetic properties of Fe O films deposited via reactive sputtering are investigated. In par- ticular@Andrew.cmu.edu). Digital Object Identifier 10.1109/TMAG.2003.815718 Fig. 1. Glancing-angle XRD patterns of Fe O films

Laughlin, David E.

294

Structural and magnetic properties of nanocrystalline BaFe12O19 synthesized by microwave-hydrothermal method  

NASA Astrophysics Data System (ADS)

Nanocrystalline BaFe12O19 powders were prepared by microwave-hydrothermal method at 200 °C/45 min. The as-synthesized powders were characterized by using X-ray diffraction (XRD), thermogravimetry (TG) and differential thermal analysis (DTA). The present powders were densified at different temperatures, i.e., 750, 850, 900 and 950 °C for 1 h using microwave sintering method. The phase formation and morphology studies were carried out using XRD and field emission scanning electron microscopy (FE-SEM). The average grain sizes of the sintered samples were found to be in the range of 185-490 nm. The magnetic properties such as saturation magnetization and coercive field of sintered samples were calculated based on magnetization curves. A possible relation between the magnetic hysteresis curves and the microstructure of the sintered samples was investigated.

Sadhana, K.; Praveena, K.; Matteppanavar, S.; Angadi, B.

2012-09-01

295

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

NASA Astrophysics Data System (ADS)

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.

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

2013-03-01

296

Magnetic and structural properties of ferrofluids based on Cobalt-Zinc ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Ferrofluids are colloidal systems composed of a single domain of magnetic nanoparticles with a mean diameter around 10 nm, dispersed in a liquid carrier. Magnetic Co(1-x)ZnxFe2O4 ferrite nanoparticles were prepared via co-precipitation method from aqueous salt solutions in an alkaline medium. The composition and structure of the samples were characterized through EDX and XRD, respectively. Transmission Electron Microscopy studies permitted determining nanoparticle size. Grain size of nanoparticle conglomerates was established via Atomic Force Microscopy. The magnetic behavior of ferrofluids was characterized by Vibrating Sample Magnetometer; and finally, a Magnetic Force Microscope was used to visualize the magnetic domains of nanoparticles. The mean size of the crystallite of nanoparticles determined by using the Scherrer approximation diminished when the Zn concentration increases. The size of the nanoparticles obtained by TEM is in good agreement with the crystallite size calculated from XRD measures. The magnetic properties investigated at room temperature presented super-paramagnetic behavior, determined by the shape of the hysteresis loop. Finally, our magnetic nanoparticles are considered a soft magnetic material.

Prieto, P.; Lopez, J.; Gomez, M. E.; Prado, J.; Caicedo, J.; Zambrano, G.; Gonzalez, L.; Esteve, J.

2012-02-01

297

Magnetic Bearing  

NASA Technical Reports Server (NTRS)

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.

1996-01-01

298

Lunar magnetism  

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

299

Studies on the formation, structure and magnetic properties of Cr substituted Sm 2(Fe, Cr) 17C x compounds  

Microsoft Academic Search

The effects of Cr substitution on the formation, structure and magnetic properties of Sm2(Fe, Cr)17Cx compounds have been systematically studied on arc-melted and melt-spun samples using XRD, TEM and magnetic measurements. It has been found that Cr substitution is an effective way to form the Sm2(Fe, Cr)17Cx carbides. The minimum Cr amount for Sm2Fe17?yCryC2 to form an almost single 2

Zhongmin Chen; G. C. Hadjipanayis

1997-01-01

300

Preparation and properties of Zn 0.9 Ni 0.1 O diluted magnetic semiconductor nanoparticles  

Microsoft Academic Search

With a view to study the structural, electronic, magnetic, and electrical properties of Zn0.9Ni0.1O diluted magnetic semiconductor nanoparticles, systematic investigation has been undertaken. Samples were prepared for the\\u000a first time by hydrazine-assisted polyol method, and the powders were annealed at various temperatures in order to obtain the\\u000a samples with different grain sizes. From the Rietveld refined XRD data, lattice parameters,

K. Srinivas; S. Manjunath Rao; P. Venugopal Reddy

2011-01-01

301

Synthesis of high magnetization Fe and FeCo nanoparticles by high temperature chemical reduction  

NASA Astrophysics Data System (ADS)

Fe and FeCo ferromagnetic nanoparticles in the 5-10 nm size regimes featuring high magnetization were synthesized using a modified chemical reduction method. The structure and morphology of these nanoparticles were confirmed by XRD and TEM analysis. These small, monodisperse and phase pure nanoparticles exhibited magnetic saturation of 210 emu/g (Fe) and 220 emu/g (Fe+Co) for Fe and FeCo nanoparticles respectively. The magnetization was found to be dependent on the temperature at which the reducing agent was introduced.

Kandapallil, Binil; Colborn, Robert E.; Bonitatibus, Peter J.; Johnson, Francis

2015-03-01

302

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

NASA Astrophysics Data System (ADS)

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.

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

2013-02-01

303

Superconducting magnets  

SciTech Connect

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.

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

1985-01-01

304

Magnetic monopoles  

SciTech Connect

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.

Fryberger, D.

1984-12-01

305

Magnetic properties of YIG doped with cerium and gadolinium ions  

Microsoft Academic Search

Nanoparticles Y3?x?y\\u000a Ce\\u000a x\\u000a Gd\\u000a y\\u000a Fe5O12 (x = 0–0.1, y = 0–1.0) were fabricated by a sol–gel method. The crystalline structures and magnetic properties of samples were investigated\\u000a by X-ray diffraction (XRD), scanning probe microscopy (SPM), X-ray photoelectron spectroscopy (XPS), and vibrating sample\\u000a magnetometer (VSM). The XRD patterns of Y3?x?y\\u000a Ce\\u000a x\\u000a Dy\\u000a y\\u000a Fe5O12 have only peaks of the garnet structure and

Haitao Xu; Hua Yang

2008-01-01

306

Magnetism in Mo-doped Yttrium Iron Garnet  

NASA Astrophysics Data System (ADS)

Yttrium iron garnet (YIG) is a synthetic garnet and ferrimagnetic, with chemical formula Y3Fe5O12. In YIG, five iron (III) ions occupy two octahedral and three tetrahedral sites, with the yttrium (III) ions coordinated by eight oxygen ions in an irregular cube. The iron ions in the two coordination sites exhibit different spins, resulting in magnetic behavior. Bulk YIG has been synthesized systematically by solid state reaction method. The formation of pure YIG have been investigated through X-ray diffraction (XRD) beginning from weighing in molar proportions of Y2O3 and Fe2O3, mixing and grinding, pre-sintering and final sintering at 1300 ^oC. XRD study shows that YIG exhibits cubic structure with lattice constant of about 12 å. Magnetization with varying field and temperature has been measured using a SQUID magnetometer. Magnetic measurement of Mo YIG has shown that magnetic moment increase initially and then decreases with Mo doping. Detailed results will be discussed in this presentation. This work is supported by National Science Foundation (Award Number DMR-0907037).

Khanra, S.; Kolekar, Y.; Langhoff, M.; Kahol, P.; Ghosh, K.

2013-03-01

307

Solar Magnetism  

NSDL National Science Digital Library

The Sun appears to shine at a constant rate. However, its magnetic field is actually constantly changing, and this affects energy output. These variations cause effects that extend throughout the solar system. This video segment, adapted from a NOVA television broadcast, introduces viewers to some of the effects of the sun's magnetic field, such as sunspots, auroras, and variations in the sunspot cycle which may affect Earth's climate. The segment is two minutes fifty seconds in length.

2011-05-10

308

Solar Magnetism  

NSDL National Science Digital Library

The Sun appears to shine at a constant rate. However, its magnetic field is actually constantly changing, and this affects energy output. These variations cause effects that extend throughout the solar system. This video segment, adapted from a NOVA television broadcast, introduces viewers to some of the effects of the sun's magnetic field, such as sunspots, auroras, and variations in the sunspot cycle which may affect Earth's climate. The segment is two minutes fifty seconds in length.

309

Superconducting magnet  

NASA Technical Reports Server (NTRS)

Extensive computer based engineering design effort resulted in optimization of a superconducting magnet design with an average bulk current density of approximately 12KA/cm(2). Twisted, stranded 0.0045 inch diameter NbTi superconductor in a copper matrix was selected. Winding the coil from this bundle facilitated uniform winding of the small diameter wire. Test coils were wound using a first lot of the wire. The actual packing density was measured from these. Interwinding voltage break down tests on the test coils indicated the need for adjustment of the wire insulation on the lot of wire subsequently ordered for construction of the delivered superconducting magnet. Using the actual packing densities from the test coils, a final magnet design, with the required enhancement and field profile, was generated. All mechanical and thermal design parameters were then also fixed. The superconducting magnet was then fabricated and tested. The first test was made with the magnet immersed in liquid helium at 4.2K. The second test was conducted at 2K in vacuum. In the latter test, the magnet was conduction cooled from the mounting flange end.

1985-01-01

310

?-MnAl with high coercivity and saturation magnetization  

NASA Astrophysics Data System (ADS)

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%.

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

311

Magnetization Reversal in Fe Doped SmCrO3  

NASA Astrophysics Data System (ADS)

The compound SmCr1-xFexO3 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 to 400 K at 0.01T field and -5T to 5 T field at 2K. SmCrO3 compound has shown two magnetic transition temperatures (TN1 and TN2) at 197 K and 38 K. The observed behavior at 197 K is the characteristic of anti-ferromagnetic ordering of Cr 3+ moments with weak ferromagnetism. The drop in magnetization below 38 K is due to the spin reorientation of Sm3+ in anti ferromagnetic arrangement and Cr3+spins. The doping of Fe in SmCrO3 compound has shown a decrease in TN1 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.

Bakshi, Venugopal Rao; Bandi, Vittal Prasad; Gade, Narsinga Rao; Chou, F. C.; Devarasetty, Suresh Babu

312

Magnets 1: Magnetic Pick-ups  

NSDL National Science Digital Library

This lesson provides students with an understanding that certain materials are attracted to magnets while others are not. It is the first in a two-lesson series on magnets. In Magnets 1: Magnetic Pick-ups, students will look at various objects, make predictions about whether they are magnetic, and then test their predictions. This exploration is an introductory activity to magnets and magnetism.

313

Neutrino magnetic moment in a magnetized plasma  

E-print Network

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.

N. V. Mikheev; E. N. Narynskaya

2010-11-08

314

Synthesis, characterization and magnetic properties of Cr-substituted Co-Zn ferrites nanopowders  

NASA Astrophysics Data System (ADS)

Nano-crystalline ferrites; Co0.9Zn0.1Fe2-xCrxO4 (where x = 0-1) have been synthesized through thermal decomposition reaction of their respective oxalates. The effect of Cr3+ ion substitution on the structural and magnetic properties was studied. Differential thermal analysis-thermogravimetry (DTA-TG) techniques were used to characterize the oxalates decomposition reaction and following ferrite formation. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), transmission electron microscopy (TEM) and vibrating scanning magnetometry (VSM) were used to characterize the structural, morphological and magnetic properties. XRD revealed single-phase cubic spinels. Both crystallite size and lattice parameter decreases with increasing Cr-content. FT-IR spectral studies confirmed the suggested cation distribution estimated through XRD measurements. TEM image showed agglomerated spherical nanoparticles with size of about 20 nm. The gradual decrease in the saturation magnetization, estimated through VSM measurements, with increasing Cr-content suggests the preferential occupation of Cr3+ ions in the octahedral sites and confirmed the suggested cation distribution while, the decrease in the coercivity values indicating the loss of magneto-crystalline anisotropy. The decrease in the Curie temperatures obtained from dc-magnetic susceptibility with the increasing chromium can be attributed to the decrease in the A-B exchange interaction.

Gabal, M. A.; Al Angari, Y. M.; Al-Agel, F. A.

2013-03-01

315

Synthesis and characterization of ball milled Fe-doped ZnO diluted magnetic semiconductor  

NASA Astrophysics Data System (ADS)

Fe-doped ZnO (Zn0.99Fe0.01O) powders are successfully prepared by ball milling with different milling time, and are investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), ultraviolet-visible (UV-VIS) spectroscopy, vibrating sample magnetometer (VSM) and electron paramagnetic resonance (EPR) spectroscopy. The structural analysis using XRD reveals that the Fe-doped ZnO milled at different milling time can crystallize in a wurtzite structure, and in the XRD patterns, the secondary phase related to Fe cluster with the sensitivity of the XRD instrument can not be found. The SEM image of the sample milled for 24 h shows the presence of spherical nanoparticles. From the optical analysis, the optical band gap is found to decrease with increasing the milling time, which indicates the incorporation of Fe2+ ions into the ZnO lattice. The magnetization measurement using VSM reveals that the nanoparticles exhibit ferromagnetic behavior at room temperature, and the magnetization increases gradually with increasing the milling time. The conclusion is further confirmed by the electron paramagnetic resonance of the nanoparticles examined at room temperature, which shows an intense and broad ferromagnetic resonance signal related to Fe ions.

Elilarassi, R.; Chandrasekaran, G.

2012-03-01

316

Magnetic Texturing of Xenon-Irradiated Iron Films Studied by Magnetic Orientation Mössbauer Spectroscopy  

NASA Astrophysics Data System (ADS)

Modifications of magnetic properties upon heavy-ion irradiation have been recently investigated for films of ferromagnetic 3d-elements (Fe, Ni, Co) and alloys (permendur, permalloy), in relation to changes of their microstructure. Here we report on Xe-ion irradiation of a highly textured iron film prepared via pulsed-laser deposition on a MgO(100) single crystal and containing a thin 57Fe marker layer for magnetic orientation Mössbauer spectroscopy (MOMS). We compare the results with those obtained for a polycrystalline Fe/Si(100) sample produced by electron evaporation and premagnetized before Xe-irradiation in a 300 Oe external field. Characterization of the samples also included magneto-optical Kerr effect (MOKE), Rutherford backscattering spectroscopy (RBS) and X-ray diffraction (XRD).

Müller, G. A.; Lieb, K. P.; Carpene, E.; Zhang, K.; Schaaf, P.; Faupel, J.; Krebs, H. U.

2004-11-01

317

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

NASA Astrophysics Data System (ADS)

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.

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

2012-02-01

318

Permanent Bar Magnets  

NSDL National Science Digital Library

This is an activity about the basic properties of magnets and magnetism. Learners explore concepts such as magnetic fields and polarity, which form the basic ingredients of a study of Earth's magnetic field and the technology of magnetometers. Materials needed include bar magnets and paper clips. This is Activity 1 of Exploring Magnetism: A Teacher's Magnetism Activity Guide.

319

Photoluminescence and magnetic properties of Fe-doped ZnS nano-particles synthesized by chemical co-precipitation  

Microsoft Academic Search

This paper is focusing on the synthesis of Zn1?xFexS nano-particles with x=0, 0.1 and 0.2 by chemical co-precipitation method, the prepared of which are characterized by XRD, EDS, TEM, PL, magnetization versus field behavior and M–T curve. In the XRD patterns, Zn1?xFexS nano-particles are shown of cubic zinc blende structure, and the broadening diffraction peaks consistent with the small-size characteristic

Nie Eryong; Liu Donglai; Zhang Yunsen; Bai Xue; Yi Liang; Jin Yong; Jiao Zhifeng; Sun Xiaosong

2011-01-01

320

Synthesis and characterization of functional magnetic nanocomposites  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles and carbon nanotubes have been excellent functional materials that could be dispersed in polymer matrices for various applications. However, uniform dispersion of particles in polymers without agglomeration is quite challenging. We have fabricated PMMA/polypyrrole bilayer structures embedded with Fe3O4 magnetite nanoparticles synthesized using wet chemical synthesis. Agglomeration-free dispersion of nanoparticles was achieved by coating the particles with surfactants and by dissolving both the particles and PMMA in chlorobenzene. Structural characterization was done using XRD and TEM. Magnetic properties of the bilayer structures indicated superparamagnetic behavior that is desirable for RF applications as the magnetic losses are reduced. Our polymer nanocomposite bilayer films with conducting polymer coatings are potential candidates for tunable RF applications with integrated EMI suppression. We will also report on our studies of pumped ferrofluids flowing past carbon nanotubes that are arranged in microchannel arrays. Magnetization under various flow conditions is investigated and correlated with the hydrodynamic properties. This scheme provides a novel method of energy conversion and storage using nanocomposite materials.

Gass, J.; Sanders, J.; Srinath, S.; Srikanth, H.

2006-03-01

321

Synthesis and applications of quantum dots and magnetic quantum dots  

NASA Astrophysics Data System (ADS)

We have developed a new synthetic method for producing high-quality quantum dots (QDs) in aqueous solution for biological imaging applications. The glutathione-capped CdTe, ZnSe and Zn 1-xCd xSe alloyed QDs derived are tunable in fluorescence emissions between 360 nm and 700 nm. They show high quantum yields (QYs) of up to 50%, with narrow bandwidths of 19-55 nm. The synthesis of glutathione-capped QDs is simple and cost-effective compared to the conventional organometallic approaches. It can be easily scaled up for the commercial production of alloyed nanocrystals of various compositions. We have also demonstrated the fabrication of magnetic quantum dots (MQDs) through a seed-mediated approach. The formation and assembly of these bifunctional nanocomposites have been elucidated by high-resolution transmission electron microscopy (HRTEM). The MQDs exhibit superparamagnetism and tunable emissions characteristic of the components in this hybrid system. We have created biocompatible silica-coated MQDs that effectively target the cell membranes.

Ying, Jackie Y.; Zheng, Yuangang; Selvan, S. Tamil

2008-02-01

322

Temperature-induced phenomena in systems of magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

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.

Bhuiya, Abdul Wazed

323

Magnetic light  

PubMed Central

Spherical silicon nanoparticles with sizes of a few hundreds of nanometers represent a unique optical system. According to theoretical predictions based on Mie theory they can exhibit strong magnetic resonances in the visible spectral range. The basic mechanism of excitation of such modes inside the nanoparticles is very similar to that of split-ring resonators, but with one important difference that silicon nanoparticles have much smaller losses and are able to shift the magnetic resonance wavelength down to visible frequencies. We experimentally demonstrate for the first time that these nanoparticles have strong magnetic dipole resonance, which can be continuously tuned throughout the whole visible spectrum varying particle size and visually observed by means of dark-field optical microscopy. These optical systems open up new perspectives for fabrication of low-loss optical metamaterials and nanophotonic devices. PMID:22768382

Kuznetsov, Arseniy I.; Miroshnichenko, Andrey E.; Fu, Yuan Hsing; Zhang, JingBo; Luk’yanchuk, Boris

2012-01-01

324

Magnet Man: Cool Experiments with Magnets  

NSDL National Science Digital Library

This web site contains a set of curriculum materials for middle school and high school on the topic of magnetism. Topics include magnet basics, electromagnets, magnetic fields, superconductors, magnetic levitation, and applications of magnetic properties. It is organized sequentially, with a concept-building approach. Each unit is supported with videos and hands-on experiments, as well as links to background information.

Hoadley, Rick

2010-04-01

325

Preparation and magnetic properties of (Zn-Sn) substituted barium hexaferrite nanoparticles for magnetic recording  

NASA Astrophysics Data System (ADS)

Zn-Sn substituted barium ferrite particles BaFe 12-2 xZn xSn xO 19 with 0? x?1.1 have been prepared by a chemical co-precipitation method for the first time. X-ray diffraction (XRD) and transition electron microscopy (TEM) have been carried out to determine the particle structure and morphology. Magnetic properties have been measured using a vibrating sample magnetometer (VSM) with an applied field up to 80 kOe. The specific saturation magnetization Ms was determined using the law of approach to saturation, and the effective anisotropy field Ha and anisotropy constant K1 were also estimated. It was found that the particle size could be effectively decreased and coercivity Hc easily controlled, by varying x without significantly decreasing saturation magnetization. In particular, BaFe 12-2 xZn xSn xO 19 with x=0.7-1.1 has suitable magnetic characteristics and a particle size small enough for high-density magnetic recording.

Fang, H. C.; Yang, Z.; Ong, C. K.; Li, Y.; Wang, C. S.

1998-08-01

326

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

PubMed Central

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. PMID:25246875

2014-01-01

327

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

NASA Astrophysics Data System (ADS)

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.

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

328

Doxorubicin-loaded magnetic gold nanoshells for a combination therapy of hyperthermia and drug delivery.  

PubMed

In the present work, nanohybrid of an anticancer drug, doxorubicin (Dox) loaded gold-coated superparamagnetic iron oxide nanoparticles (SPIONs@Au) were prepared for a combination therapy of cancer by means of both hyperthermia and drug delivery. The Dox molecules were conjugated to SPIONs@Au nanoparticles with the help of cysteamine (Cyst) as a non-covalent space linker and the Dox loading efficiency was investigated to be as high as 0.32 mg/mg. Thus synthesized particles were characterized by HRTEM, UV-Vis, FT-IR, SQUID magnetic studies and further tested for heat and drug release at low frequency oscillatory magnetic fields. The hyperthermia studies investigated to be strongly influenced by the applied frequency and the solvents used. The Dox delivery studies indicated that the drug release efficacy is strongly improved by maintaining the acidic pH conditions and the oscillatory magnetic fields, i.e. an enhancement in the Dox release was observed from the oscillation of particles due to the applied frequency, and is not effected by heating of the solution. Finally, the in vitro cell viability and proliferation studies were conducted using two different immortalized cell lines containing a cancerous (MCF-7 breast cancer) and non-cancerous H9c2 cardiac cell type. PMID:25170601

Mohammad, Faruq; Yusof, Nor Azah

2014-11-15

329

Fe:O:C grown by focused-electron-beam-induced deposition: magnetic and electric properties.  

PubMed

We systematically study the effect of oxygen content on the magneto-transport and microstructure of Fe:O:C nanowires deposited by focused-electron-beam-induced (FEBID) deposition. The Fe/O ratio can be varied with an Fe content varying between ? 50 and 80 at.% with overall low C content (?16 ± 3 at.%) by adding H(2)O during the deposition while keeping the beam parameters constant as measured by energy dispersive x-ray (EDX) spectroscopy. The room-temperature magnetic properties for deposits with an Fe content of 66-71 at.% are investigated using the magneto-optical Kerr effect (MOKE) and electric magneto-transport measurements. The nanostructure of the deposits is investigated through cross-sectional high-resolution transmission electron microscopy (HRTEM) imaging, allowing us to link the observed magneto-resistance and resistivity to the transport mechanism in the deposits. These results demonstrate that functional magnetic nanostructures can be created, paving the way for new magnetic or even spintronics devices. PMID:21135470

Lavrijsen, R; Córdoba, R; Schoenaker, F J; Ellis, T H; Barcones, B; Kohlhepp, J T; Swagten, H J M; Koopmans, B; De Teresa, J M; Magén, C; Ibarra, M R; Trompenaars, P; Mulders, J J L

2011-01-14

330

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)

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.

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

2014-10-01

331

Ionic, XRD, dielectric and cyclic voltammetry studies on PVdF-co-HFP / MMT clay intercalated LiN(C2F5SO2)2 based composite electrolyte for Li-ion batteries  

NASA Astrophysics Data System (ADS)

The composition dependence of plasticizer, (EC/DMC)(70-x(wt%)) and LiBETIx(wt%) salt for fixed contents on PVdF-co-HFP(25wt%)/surface modified(SM)-octadecylamine MMT(ODA-MMT) nanoclay(5wt%) host matrix by varying its compositions x=1.5, 3.0, 4.5, 6.0 wt% prepared via solution casting technique has been investigated by A.C. Impedance, Dielectric, XRD, and cyclic voltammetry(CV) studies. The enhanced conductivity 2.1×10-5 S/cm at 300C is observed for (EC/DMC)(70-6)wt%/LiBETI(x=6)wt%. The XRD at 2?=20.9° confirms ?-phase formation, and CV studies on membranes show cyclability and reversibility. The dielectric studies show increase in dielectric constant and dielectric loss with decrease in frequency is attributed to high contribution of charge accumulation at the electrode-electrolyte interface.

Vickraman, P.; Purushothaman, K.; SankaraSubramanian, N.

2014-04-01

332

Gas-phase synthesis of magnetic metal/polymer nanocomposites.  

PubMed

Highly magnetic metal Co nanoparticles were produced via reducing flame spray pyrolysis, and directly coated with an epoxy polymer in flight. The polymer content in the samples varied between 14 and 56 wt% of nominal content. A homogenous dispersion of Co nanoparticles in the resulting nanocomposites was visualized by electron microscopy. The size and crystallinity of the metallic fillers was not affected by the polymer, as shown by XRD and magnetic hysteresis measurements. The good control of the polymer content in the product nanocomposite was shown by elemental analysis. Further, the successful polymerization in the gas phase was demonstrated by electron microscopy and size measurements. The presented effective, dry and scalable one-step synthesis method for highly magnetic metal nanoparticle/polymer composites presented here may drastically decrease production costs and increase industrial yields. PMID:25422410

Starsich, Fabian H L; Hirt, Ann M; Stark, Wendelin J; Grass, Robert N

2014-12-19

333

Controllable synthesis of nickel dendritic crystals induced by magnetic field  

SciTech Connect

We demonstrated in this paper a simple and easy method for the preparation of dendritic nickel crystals in an external magnetic field in boiling ethylene glycol (EG) solution. The structural features and morphology of the sample were investigated using powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The values of saturation magnetization (M{sub s}) and coercivity (H{sub c}) of the dendritic crystals characterized by using a vibrating sample magnetometer (VSM) are 170.3 emu g{sup -1} and 50.7 Oe, respectively. It was clear that the external magnetic field was the most important factor for controlling the morphology of the product.

Zhang Xia [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Laboratory of Special Functional Materials, Henan University, Kaifeng 475001 (China); Graduate School of Chinese Academy of Science, Beijing 100039 (China); Liu Weimin [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)], E-mail: wmliu@lzb.ac.cn

2008-08-04

334

Experimental investigation of thermal conductivity of magnetic nanofluids  

NASA Astrophysics Data System (ADS)

Two different magnetic nanofluids comprising of magnetite and Mn-Zn ferrite particles were synthesized in light hydrocarbon oil using continuous chemical process. Powder XRD and TEM image show single phase spinel structure with size of 10 nm and 6.7 nm, respectively for magnetite and Mn-Zn ferrite. Thermal conductivity of nanofluids has been studied as a function of volume fraction under transverse magnetic field. Magnetite nanofluid shows 17% enhancements in thermal conductivity for 4.7% volume fraction while Mn-Zn ferrite shows 45% enhancement at 10% volume fraction. In presence of transverse magnetic field the magnetite nanofluids shows further enhancement from 17% to 30% while no change in thermal conductivity has been observed for Mn-Zn ferrite. These results are explained considering the dipolar coupling co-efficient which for magnetite particles favors chain structures.

Parekh, Kinnari; Lee, H. S.

2012-06-01

335

Fabrication of BaFe12O19 Nanowires by a Hydrothermal Process and Their Magnetic Properties  

NASA Astrophysics Data System (ADS)

Magnetic BaFe12O19 nanowires have been prepared by a hydrothermal process. The nanowires with diameters ~ 15 nm and lengths ~ 2 ?m are clearly visible in Transmission Electron Microscopy (TEM) image. The physical properties of the BaFe12O19 nanowires were further characterized by X-ray diffraction (XRD) and magnetization measurement. The results of the magnetization measurement show that the sample displays ferromagnetic properties at room temperature and its saturation magnetization (Ms) reaches 13.36 emu/g. Annealing treatment of the sample in air at 800°C leads to the increasing of the saturation magnetization (Ms: 65.7 emu/g). It is suggested that the oxygen vacancies should be responsible for the low saturation magnetization, which is also supported by the magnetic property (Ms: 21.6 emu/g) of the sample annealed at 800°C in argon shield.

Wang, Jun; Zhu, Yuejin

336

XRD and EXAFS studies on the structure of Er3+-doped SiO2-HfO2 glass-ceramic waveguides: Er3+-activated HfO2 nanocrystals  

NASA Astrophysics Data System (ADS)

This paper describes the structure of Er3+-doped SiO2-HfO2 waveguides containing nanocrystals of HfO2. Pure and 1 mol% Er3+-doped 70SiO2-30HfO2 films were deposited by the sol-gel method on amorphous SiO2 substrates using the dip-coating technique. Each waveguide has experienced a single thermal treatment at temperatures ranging from 900 to 1200 °C, for either short (30 min) or long (24 h) durations. Crystallization and microstructure were studied by x-ray diffraction (XRD). The local environments of hafnium and erbium ions were determined, respectively, from Hf and Er L3-edges extended x-ray absorption fine structure (EXAFS) experiments. Both XRD and EXAFS results demonstrate the substitution of Hf4+ by Er3+ ions in the crystalline structure. XRD shows the nucleation of tetragonal HfO2 nanocrystals after heat treatment at 1000 °C for 30 min in the pure waveguide, and at 900 °C for 24 h in the waveguide doped with Er3+. In both series, partial transformation from tetragonal to monoclinic HfO2 nanocrystals starts after heat treatment at 1100 °C for 24 h. The average crystallite size and size distribution can be controlled by thermal annealing temperature and duration, respectively, with brief treatment yielding a more homogeneous nanocrystal size.

Afify, N. D.; Dalba, G.; Rocca, F.

2009-06-01

337

Exploring Magnetism: Investigating the forces of magnets  

NSDL National Science Digital Library

This activity is a classroom and lab investigation of magnetism. Students gather results of experiments involving the forces of magnets. They use this data to develop their own experiments to test properties of magnets.

338

Effect of zinc doping on magnetic and magnetoelastic properties of cobalt ferrite synthesized by autocombustion process  

NASA Astrophysics Data System (ADS)

Zn-doped cobalt-ferrite, with nominal compositions Co1-xZnxFe2O4(0?x?0.3), were synthesized by a novel auto combustion technique. The structural properties of the Zn substituted ferrites have been characterized using x-ray diffraction (XRD). The as-synthesized powders were calcined at 800°C for 3 hrs and the powders were pressed into cylindrical pellets. Solid-state sintering at 1300°C for 12 hrs of the green pellets resulted in a single phase cubic-spinel structure, as observed and analyzed from the XRD spectra. Room temperature magnetic properties were studied using vibrating sample magnetometer (VSM) with field strengths up to ± 15 kOe. Magnetoelastic properties were measured using strain gauge method in a pulsed field magnetometer. Effect of zinc doping on its magnetic and magnetoelastic properties of cobalt ferrite is discussed in this paper.

Reddy, M. Vinitha; Paul, J. Praveen; Das, Dibakar

2013-06-01

339

The photoluminescence and magnetic properties of ZnAl2O4:Mn nanocrystals  

NASA Astrophysics Data System (ADS)

The single-phase ZnAl2O4 phosphors with various components of Mn2+ dopant were fabricated by using hydrothermal method. The phosphors has been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL) spectra and vibrating sample magnetometer (VSM). The results of XRD and TEM measurements showed that the resultant nanoparticles were single crystal with octahedral and hexagonal shape, and after annealed, this shape had change. Green emission was observed from doped zinc aluminate with 427 nm excitation. The temperature-dependant PL spectra revealed two emission peaks which exhibited different shifting tendency with a decrease in temperature. The room-temperature hysteresis loops of zinc aluminate nanoparticles showed magnetic behavior, and the magnetism disappeared gradually with the increase of Mn2+ doping contents.

Zhang, Dong; Yin, Yuli; Liu, Yunlong; Chao, Wenbiao; Zhai, Ya

2013-08-01

340

Magnetic catalysis versus magnetic inhibition.  

PubMed

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 enhances the chiral-symmetry breaking at finite B according to the magnetic catalysis, while the latter suppresses 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. PMID:23373911

Fukushima, Kenji; Hidaka, Yoshimasa

2013-01-18

341

Magnetic Catalysis vs Magnetic Inhibition  

E-print Network

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.

Kenji Fukushima; Yoshimasa Hidaka

2012-09-06

342

?-Sheet Nanocrystalline Domains Formed from Phosphorylated Serine-Rich Motifs in Caddisfly Larval Silk: A Solid State NMR and XRD Study  

PubMed Central

Adhesive silks spun by aquatic caddisfly (order Trichoptera) larvae are used to build both intricate protective shelters and food harvesting nets underwater. In this study, we use 13C and 31P solid-state Nuclear Magnetic Resonance (NMR) and Wide Angle X-ray Diffraction (WAXD) as tools to elucidate molecular protein structure of caddisfly larval silk from the species Hesperophylax consimilis. Caddisfly larval silk is a fibroin protein based biopolymer containing mostly repetitive amino acid motifs. NMR and X-ray results provide strong supporting evidence for a structural model in which phosphorylated serine repeats (pSX)4 complex with divalent cations Ca2+ and Mg2+ to form rigid nanocrystalline ?-sheet structures in caddisfly silk. 13C NMR data suggests that both phosphorylated serine and neighboring valine residues exist in a ?-sheet secondary structure conformation while glycine and leucine residues common in GGX repeats likely reside in random coil conformations. Additionally, 31P chemical shift anisotropy (CSA) analysis indicates that the phosphates on phosphoserine residues are doubly ionized, and are charge-stabilized by divalent cations. Positively charged arginine side chains also likely play a role in charge stabilization. Finally, WAXD results finds that the silk is at least 7–8% crystalline, with ?-sheet inter-plane spacings of 3.7 and 4.5 Å. PMID:23452243

Addison, J. Bennett; Ashton, Nicholas N.; Weber, Warner S.; Stewart, Russell J.; Holland, Gregory P.; Yarger, Jeffery L.

2013-01-01

343

Cereal Magnets  

NSDL National Science Digital Library

Student groups compete to design a process that removes the most iron from fortified cereal. Students experiment with different materials using what they know about iron, magnets and forces to design the best process for removing iron from the cereal samples.

Engineering K-Phd Program

344

Magnetic Insulation  

Microsoft Academic Search

The present understanding of magnetic insulation is reviewed. For stationary flows in constant impedance regions, the single particle description, laminar flow theory, quasi-aminar flow, and flows with arbitrary momenta are presented. Then, nonstationary flows and their laminar flow approximations, the minimum energy operating point, and some questions on their stability are discussed. Equivalent circuit simulations, particle in cell simulations, and

Marco S. Di Capua

1983-01-01

345

Magnetic Stereoscopy  

E-print Network

The space mission STEREO will provide images from two viewpoints. An important aim of the STEREO mission is to get a 3D view of the solar corona. We develop a program for the stereoscopic reconstruction of 3D coronal loops from images taken with the two STEREO spacecraft. A pure geometric triangulation of coronal features leads to ambiguities because the dilute plasma emissions complicates the association of features in image 1 with features in image 2. As a consequence of these problems the stereoscopic reconstruction is not unique and multiple solutions occur. We demonstrate how these ambiguities can be resolved with the help of different coronal magnetic field models (potential, linear and non-linear force-free fields). The idea is that, due to the high conductivity in the coronal plasma, the emitting plasma outlines the magnetic field lines. Consequently the 3D coronal magnetic field provides a proxy for the stereoscopy which allows to eliminate inconsistent configurations. The combination of stereoscopy and magnetic modelling is more powerful than one of these tools alone. We test our method with the help of a model active region and plan to apply it to the solar case as soon as STEREO data become available.

Thomas Wiegelmann; Bernd Inhester

2006-12-21

346

Magnets 2: How Strong is Your Magnet?  

NSDL National Science Digital Library

In this lesson, students will experimentally measure the strength of a magnet and graph how the strength changes as the distance from the magnet increases, and as the barrier (masking tape) is built between the magnet and an iron object. This lesson is the second in a two-lesson series on magnets. The main concept to convey in Magnets 2: How Strong is Your Magnet? is that forces can act from a distance.

347

Magnets for Pain Relief  

MedlinePLUS

Magnets for Pain Relief On this page: Introduction Key Points About Magnets Safety and Side Effects What ... help ensure coordinated and safe care. Top About Magnets A magnet produces a measurable force called a ...

348

Evaluation the Impact of Annealing on Phase Evolution, Microstructure, and Magnetic Properties of Nanocrystalline Ball-Milled LiSm Ferrite  

NASA Astrophysics Data System (ADS)

The impact of milling and subsequent annealing on the phase evolution, microstructure and magnetic properties of Li0.5Sm x Fe2.5- x O4 ( x = 0, 0.05, 0.1, 0.2) ferrite prepared by mechanical alloying was investigated. X-ray diffraction (XRD), scanning electron microscope, Fourier transform infrared spectroscopy, laser particle size analysis, and vibrating sample magnetometry were employed to characterize the prepared LiSm compound. The structure was evaluated by XRD, confirmed the formation of its single-phase spinel structure. The magnetic properties of the milled nanostructured powder were extensively affected by the annealing temperature. The substitution of samarium significantly influences the magnetic characteristics, proved by magnetization measurements at room temperature.

Mahmoudi, M.; Kavanlouei, M.; Maleki-Ghaleh, H.

2014-09-01

349

Magnetic chitosan\\/iron (II, III) oxide nanoparticles prepared by spray-drying  

Microsoft Academic Search

Chitosan\\/iron (II, III) oxide nanoparticles with various ratios of chitosan\\/iron (CS1\\/Fe4, CS2\\/Fe4 and CS3\\/Fe4) were prepared by a spray-drying method. Atomic absorption spectrometry (AAS), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) spectrometry data confirm that magnetic crystalline Fe3O4 interacts with chitosan and distributes in the chitosan matrix. Field emission scanning electron microscopy (FESEM) micrographs indicate that nanoparticles so

Hsin-Yi Huang; Yeong-Tarng Shieh; Chao-Ming Shih; Yawo-Kuo Twu

2010-01-01

350

Preparation and characterization of magnetic chitosan nanoparticles and its application for Cu(II) removal  

Microsoft Academic Search

The magnetic chitosan nanoparticles were prepared by a simple one-step in situ co-precipitation method and characterized by means of X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier Transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM) and energy dispersive X-ray spectrometer (EDS). The sorption performance of the nanoparticles for removing Cu(II) from aqueous solution was investigated. The experimental results showed that

Chen Yuwei; Wang Jianlong

2011-01-01

351

Direct electrochemistry and electrocatalysis of hemoglobin immobilized in a magnetic nanoparticles-chitosan film  

Microsoft Academic Search

Magnetic nanoparticles (Fe3O4) were synthesized by a chemical coprecipitation method. X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to confirm the crystallite structure and the particle's radius. The Fe3O4 nanoparticles and chitosan (CS) were mixed to form a matrix in which haemoglobin (Hb) can be immobilized for the fabrication of H2O2 biosensor. The Fe3O4–CS–Hb film exhibited a pair

Na Zheng; Xia Zhou; Weiying Yang; Xiangjun Li; Zhuobin Yuan

2009-01-01

352

Magnetic properties of electron-doped Y 1? x Ce x MnO 3 compounds  

Microsoft Academic Search

Cerium-doped Y1?xCexMnO3 compounds have been prepared in single-phase form for x=0 to 0.10. X-ray diffraction (XRD) patterns could be analyzed by using P63cm space group. Temperature variations of ac susceptibility and magnetization measurements show that these Ce-doped materials exhibit weak ferromagnetic transition. The observed ferromagnetic transition is attributed to the double exchange ferromagnetic interaction between Mn2+ and Mn3+ ions due

S. K. Srivastava; Manoranjan Kar; S. Ravi; P. K. Mishra; P. D. Babu

2008-01-01

353

Magnetic properties of electron-doped Y1-xCexMnO3 compounds  

Microsoft Academic Search

Cerium-doped Y1-xCexMnO3 compounds have been prepared in single-phase form for x=0 to 0.10. X-ray diffraction (XRD) patterns could be analyzed by using P63cm space group. Temperature variations of ac susceptibility and magnetization measurements show that these Ce-doped materials exhibit weak ferromagnetic transition. The observed ferromagnetic transition is attributed to the double exchange ferromagnetic interaction between Mn2+ and Mn3+ ions due

S. K. Srivastava; Manoranjan Kar; S. Ravi; P. K. Mishra; P. D. Babu

2008-01-01

354

A Study on the Magnetic Properties of Al-Doped Sulphur Spinel  

Microsoft Academic Search

FeCr2-xAlxS4 ( x=0.1, 0.3, and 0.5) samples were prepared by solid state reaction method. The crystallographic structure and magnetic properties of the fabricated compounds were investigated by X-ray diffraction (XRD), superconducting quantum interference device (SQUID) magnetometer, and Mo¿ssbauer spectroscopy. The crystal structure is determined to be a cubic spinel with the space group of Fd-3m and the lattice constants a

Chin Mo Kim; Sam Jin Kim; Chul Sung Kim

2010-01-01

355

Correlation between texture, anisotropy, and vector magnetization processes investigated by two-dimensional vector vibrating sample  

E-print Network

VVSM . 6H-SiC 0001 single crystal wafers were cleaned in a custom-built hydrogen furnace and a 10 nm to characterize texture and magnetic domain structure for a BaO Fe2O3 6 film deposited on 0001 SiC with a MgO 111O 111 on SiC 0001 discussed in Ref. 5 is characterized by x-ray diffraction XRD and ana- lyzed

McHenry, Michael E.

356

Magnetic and dielectric properties of barium titanate-coated barium ferrite  

Microsoft Academic Search

Flaky barium ferrite with hexagonal molecular structure was successfully prepared by reverse microemulsion method, and was coated with barium titanate through a coordination–precipitation technique. The prepared composite particles were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), vibrating sample magnetometry (VSM) and vector network analyzer. Barium ferrite nanoparticles are proved to be single magnetic

Chao Wang; Xijiang Han; Ping Xu; Xiaohong Wang; Xueai Li; Hongtao Zhao

2009-01-01

357

Preparation and magnetic properties of hexagonal barium ferrite films using BaM nanoparticles  

Microsoft Academic Search

Barium ferrite (BaFe12O19—BaM) thick films have been synthesized using a spinning coating sol–gel process. The coating sol was formed from BaM powders dispersed in the BaM raw sol. XRD, SEM, EDX, vibrating sample magnetometer (VSM), and ac susceptometer, were employed to evaluate the structure, composition and magnetic properties of BaM thick films. The results indicated that a uniform and crack-free

Ali Ghasemi; Reza Shams Alam; Akimitsu Morisako

2008-01-01

358

Lepidocrocite to maghemite to hematite: A pathway to have magnetic and hematitic Martian soil  

Microsoft Academic Search

We examined decomposition products of lepidocrocite, which were produced by heating the phase in air at temperatures up to 525(C for 3 and 300 hr, by XRD, TEM, magnetic methods, and reflectance spectroscopy (visible and near-IR). Single-crystal lepidocrocite particles dehydroxylated to polycrystalline particles of disordered maghemite which subsequently transformed to polycrystalline particles of hematite. Essentially pure maghemite was obtained at

Richard V. Morris; D. C. Golden; Tad D. Shelfer; H. V. Lauer Jr.

1998-01-01

359

Nanocrystallization behavior and magnetic properties of amorphous Fe 78Si 9B 13 ribbons  

Microsoft Academic Search

The amorphous state of ferromagnetic Fe78Si9B13 ribbons and its nanocrystallization were investigated by in situ transmission electron microscope (TEM), X-ray diffraction (XRD), Mössbauer spectroscopy (MS), differential scanning calorimeters (DSC) and magnetic moment measurements. The Mössbauer spectrum exhibited an essentially symmetric hyperfine field pattern of 259kOe in as-quenched amorphous state at room temperature. The Curie and crystallization temperature were determined to

Xiangcheng Sun; A. Cabral-Prieto; M Jose Yacaman; J. Reyes-Gasga; R. Hernandez-Reyes; A. Morales; Wensheng Sun

2000-01-01

360

Superconducting Magnet Division  

E-print Network

Superconducting Magnet Division Ramesh Gupta, BNL, HTS Magnets for Accelerator and Other;Superconducting Magnet Division Ramesh Gupta, BNL, HTS Magnets for Accelerator and Other Applications, March 30 active in HTS magnet R&D for well over a decade #12;Superconducting Magnet Division Ramesh Gupta, BNL

Gupta, Ramesh

361

Domain size correlated magnetic properties and electrical impedance of size dependent nickel ferrite nanoparticles  

NASA Astrophysics Data System (ADS)

We report here the investigations on the size dependent variation of magnetic properties of nickel ferrite nanoparticles. Nickel ferrite nanoparticles of different sizes (14 to 22 nm) were prepared by the sol-gel route at different annealing temperatures. They are characterized by TGA-DTA, XRD, SEM, TEM and Raman spectroscopy techniques for the confirmation of the temperature of phase formation, thermal stability, crystallinity, morphology and structural status of the nickel ferrite nanoparticles. The magnetization studies revealed that the saturation magnetization (Ms), retentivity (Mr) increase, while coercivity (Hc) and anisotropy (Keff) decrease as the particle size increases. The observed value of Ms is found to be relatively higher for a particle size of 22 nm. In addition, we have estimated the magnetic domain size using magnetic data and correlated to the average particle size. The calculated magnetic domain size is closely matching with the particle size estimated from XRD. Impedance spectroscopy was employed to study the samples in an equivalent circuit to understand their transport phenomena. It shows that nickel ferrite nanoparticles exhibit a non-Debye behavior with increasing particle size due to the influence of increasing disorders, surface effects, grain size and grain boundaries, etc.

Kamble, Ramesh B.; Varade, Vaibhav; Ramesh, K. P.; Prasad, V.

2015-01-01

362

Magnetic bearing. [for supplying magnetic fluxes  

NASA Technical Reports Server (NTRS)

A magnetic bearing is described which includes a pair of coaxial, toroidal, and permanent magnets having axially directed poles. Like poles of the permanent magnets are adjacent to each other, whereby the permanent magnets have a tendency to be urged apart along the common axis. An electromagnet is wound coaxially with the permanent magnets in such a manner that the poles are axially directed. Between the poles of each permanent magnet there is a low magnetic reluctance circuit including two series air gaps. Between the poles of the electromagnet a low reluctance path including only one air gap of each of the low magnetic reluctance circuits is provided. The low reluctance path for the electromagnet includes a ring axially translatable relative to the permanent magnets. The ring forms opposite faces of the air gaps in the magnetic circuits for each permanent magnet.

Studer, P. A. (inventor)

1975-01-01

363

Dielectric and magnetic behavior of BaCd 2? x Sr x Fe 16O 27 W-type hexagonal ferrites  

Microsoft Academic Search

We have prepared BaCd2?xSrxFe16O27 (x=0, 0.5, 1, 1.5 and 2.0) W-type hexagonal ferrites by standard ceramic method. In this work, the structural, dielectric and magnetic properties have been studied of the prepared samples. The XRD analysis of the samples reveals single phase behavior sintered at 1400°C for 6h. The saturation magnetization (Ms) shows increasing behavior with the increasing concentration of

G. Murtaza Rai; Faiza aen; Misbah-ul-Islam; M. U. Rana

2011-01-01

364

Magnetic and dielectric properties of Mn0.2Ni0.8Fe2O4 nanoparticles synthesized by PEG-assisted hydrothermal method  

Microsoft Academic Search

We present a systematic investigation on the structural and magnetic properties of Mn0.2Ni0.8Fe2O4 nanoparticles synthesized by a polyethylene glycol (PEG)-assisted hydrothermal route. XRD, FT-IR, TEM and VSM were used for the structural, morphological, dielectric properties and magnetic investigation of the products, respectively. Average crystallite size of product was estimated using Line profile fitting as 6 ± 1 nm and particle size as 6.5 ± 1.0 nm

Y. Köseo?lu; M. Bay; Muhammed Tan; A. Baykal; H. Sözeri; R. Topkaya; N. Akdo?an

2011-01-01

365

Electrodeposition of iron and iron-aluminium alloys in an ionic liquid and their magnetic properties.  

PubMed

In this work we show that nanocrystalline iron and iron-aluminium alloys can be electrodeposited from the ionic liquid 1-butyl-1-methylpyrrolidinium trifluoromethylsulfonate, [Py1,4]TfO, at 100 °C. The study comprises CV, SEM, XRD, and magnetic measurements. Two different sources of iron(ii) species, Fe(TfO)2 and FeCl2, were used for the electrodeposition of iron in [Py1,4]TfO. Cyclic voltammetry was employed to evaluate the electrochemical behavior of FeCl2, Fe(TfO)2, and (FeCl2 + AlCl3) in the employed ionic liquid. Thick iron deposits were obtained from FeCl2/[Py1,4]TfO at 100 °C. Electrodeposition of iron-aluminium alloys was successful in the same ionic liquid at 100 °C. The morphology and crystallinity of the obtained deposits were investigated using SEM and XRD, respectively. XRD measurements reveal the formation of iron-aluminium alloys. First magnetic measurements of some deposits gave relatively high coercive forces and power losses in comparison to commercial iron-silicon samples due to the small grain size in the nanometer regime. The present study shows the feasibility of preparing magnetic alloys from ionic liquids. PMID:24715034

Giridhar, P; Weidenfeller, B; El Abedin, S Zein; Endres, F

2014-05-28

366

Magnetic domains  

NASA Astrophysics Data System (ADS)

Recently a Nahm transform has been discovered for magnetic bags, which are conjectured to arise in the large n limit of magnetic monopoles of charge n. We interpret these ideas using string theory and present evidence for this conjecture. Our main result concerns the extension of the notion of bags and their Nahm transform to higher gauge theories and arbitrary domains. Bags in four dimensions conjecturally describe the large n limit of n self-dual strings. We show that the corresponding Basu-Harvey equation is the large n limit of an equation describing n M2-branes, and that it has a natural interpretation in loop space. We also formulate our Nahm equations using strong homotopy Lie algebras.

Harland, Derek; Palmer, Sam; Sämann, Christian

2012-10-01

367

Structural and magnetic characterization of electrodeposited Ni-Cu/Cu and Fe-Ni-Cu/Cu multilayer  

NASA Astrophysics Data System (ADS)

In this research, Ni-Cu/Cu and Fe-Ni-Cu/Cu multilayers were electrodeposited on Au/Cr/glass substrate. The XRD pattern of Ni-Cu/Cu multilayer indicates satellite peaks of Ni-Cu and Cu bilayers. The EDX results had shown that the Ni content increased with increasing magnetic layers in both Ni-Cu/Cu and Fe-Ni-Cu/Cu multilayers. The AFM images had shown that increasing the magnetic and nonmagnetic layers leads to increasing surface roughness. The VSM of samples obtained the coercivity by increasing magnetic layer thickness and by decreasing the addition of Fe to Ni-Cu/Cu multilayers.

Hedayati, Kambiz

2014-11-01

368

Synthesis and magnetic properties of the SiO 2–BaFe 12O 19 glass–ceramic composites  

Microsoft Academic Search

Samples of the magnetic glass–ceramics SiO2–BaFe12O19 were obtained from mixtures of Fe2O3–BaSO4–SiO2–Na2CO3–CaCO3 following a two-step route. The samples were characterized using XRD analysis and scanning electron microscopy, and their room temperature magnetization hysteresis loops were measured. It was found that the magnetic phase was completely developed in the precursor BaFe12O19 material when it was calcinated above 1000°C. The size of

J. H. de Araújo; F. A. O. Cabral; M. F. Ginani; J. M. Soares; F. L. A. Machado

2006-01-01

369

Magnetic Reconnection  

SciTech Connect

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.

Masaaki Yamada, Russell Kulsrud and Hantao Ji

2009-09-17

370

Magnetic elements for switching magnetization magnetic force microscopy tips.  

SciTech Connect

Using combination of micromagnetic calculations and magnetic force microscopy (MFM) imaging we find optimal parameters for novel magnetic tips suitable for switching magnetization MFM. Switching magnetization MFM is based on two-pass scanning atomic force microscopy with reversed tip magnetization between the scans. Within the technique the sum of the scanned data with reversed tip magnetization depicts local atomic forces, while their difference maps the local magnetic forces. Here we propose the design and calculate the magnetic properties of tips suitable for this scanning probe technique. We find that for best performance the spin-polarized tips must exhibit low magnetic moment, low switching fields, and single-domain state at remanence. The switching field of such tips is calculated and optimum shape of the Permalloy elements for the tips is found. We show excellent correspondence between calculated and experimental results for Py elements.

Cambel, V.; Elias, P.; Gregusova, D.; Martaus, J.; Fedor, J.; Karapetrov, G.; Novosad, V. (Materials Science Division); (Slovak Academy of Sciences)

2010-09-01

371

Patterned Magnetic Nanostructures and Quantized Magnetic Disks  

E-print Network

Patterned Magnetic Nanostructures and Quantized Magnetic Disks STEPHEN Y. CHOU Invited Paper, opens up new opportunities for engineering innovative magnetic materials and devices, developing ultra-high-density magnetic storage, and understanding micromagnetics. This paper reviews the recent advances in patterned

372

Permanent magnet motor magnetizing and calibrating  

Microsoft Academic Search

The types of magnetizing equipment that are available include capacitive discharge, half-cycle and electromagnet units. The applications for, and limitations of, each type of unit are briefly reviewed. The range of permanent magnet materials commercially available. In designing an effective magnetizing and calibrating system, consideration must be given not only to the magnetizer to be used, but also to the

J. W. Aydelotte

1993-01-01

373

Structural and magnetic behaviour of soft magnetic Finemet-type ribbons.  

PubMed

Different kinds of magnetic anisotropies have been induced during the nanocrystallization process of Co- and Ni-rich amorphous ferromagnetic (Finemet) ribbons by the application of a constant stress or an axial magnetic field during the annealing process. Magnetization measurements have evidenced the presence od macroscopic anisotropy in the treated samples. The main goal of this work has been, after a careful DSC study, the structural analysis of the treated ribbons using X-ray Diffraction and Atomic Force Microscopy (AFM), detecting substantial differences in the crystallization state and grain size of the samples depending on the thermal treatment that was carried out. Moreover, AFM measurements revealed in all the treated samples a strong nanocrystallisation of the surface without evidences of amorphous matrix, which contrast with XRD measurements that have shown a high content of amorphous phase in the bulk of the ribbons. Magneto-optical Kerr effect measurements have been performed with the aim to elucidate the complex magnetic behaviour that is expected for the surface of the ribbons, measuring surface hysteresis loops that showed much higher coercive field values than that obtained in the bulk material. PMID:18681027

Iturriza, N; Fernández, L; Chizhik, A; Vara, G; Pierna, A R; del Val, J J

2008-06-01

374

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

NASA Astrophysics Data System (ADS)

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).

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

2015-01-01

375

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

376

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

SciTech Connect

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.

Jia Zhang [Department of Materials Processing Engineering, School of Materials Science and Engineering, Dalian University of Technology, Linggong Road 2, Ganjingzi District, Dalian 116085, Liaoning Province (China); Duan Yuping, E-mail: duanyp@dlut.edu.c [Department of Materials Processing Engineering, School of Materials Science and Engineering, Dalian University of Technology, Linggong Road 2, Ganjingzi District, Dalian 116085, Liaoning Province (China); Li Shuqing, E-mail: lsq6668@126.co [Beijing Aeronautical Manufacturing Technology Research Institute, 1 Jun Zhuang east Road, Chaoyang District, Beijing 100024 (China); Li Xiaogang, E-mail: lixiaogang99@263.ne [School of Materials Science and Engineering, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083 (China); Liu Shunhua [Department of Materials Processing Engineering, School of Materials Science and Engineering, Dalian University of Technology, Linggong Road 2, Ganjingzi District, Dalian 116085, Liaoning Province (China)

2010-07-15

377

Structural and magnetic characterization of as-prepared and annealed FeCoCu nanowire arrays in ordered anodic aluminum oxide templates  

SciTech Connect

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.

Rodríguez-González, B., E-mail: jbenito@uvigo.es [CACTI, University of Vigo, E-36310 Vigo (Spain); International Iberian Nanotechnology Laboratory, INL. Av. Mestre J. Veiga, 4715-330 Braga (Portugal); Bran, C.; Warnatz, T.; Vazquez, M. [Institute of Materials Science of Madrid, CSIC, 28049 Madrid (Spain); Rivas, J. [International Iberian Nanotechnology Laboratory, INL. Av. Mestre J. Veiga, 4715-330 Braga (Portugal)

2014-04-07

378

Synthesis and magnetic properties of multiwalled carbon nanotubes decorated with magnetite nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetite particles with nanoscale sizes were deposited along multiwalled carbon nanotubes (MWCNT) through a simple, effective and reproducible chemical route. The structure, morphology and magnetic properties of the hybrid materials were characterized by XRD, SEM, TEM, EDX, VSM. The characterization results show that the surface of nanotubes was loaded with iron oxides nanoclusters and each nanocluster is composed by several nanocrystals with a mean diameter of 10 nm. The experimental magnetic hysteretic behavior has been also studied by means of the Preisach model and a good agreement between experimental data and numerical computations was found.

Pistone, A.; Iannazzo, D.; Fazio, M.; Celegato, F.; Barrera, G.; Tiberto, P.; Giordano, A.; Azzerboni, B.; Galvagno, S.

2014-02-01

379

Study of structure and magnetic properties of rare earth doped BiFeO3  

NASA Astrophysics Data System (ADS)

RExBi1-xFeO3 (RE=La, Gd and Ho) samples were synthesized by a solid state reaction method and investigated for structure and magnetic properties. XRD shows that La and Ho dopings at A-site effectively reduce the secondary phase formation. A structural phase transition is observed to orthorhombic phase with all RE elements above certain concentration limit. La doping results in the observation of huge coercivity of 10 kOe and Ho doping results in high magnetic moment among all the RE elements. Gd and Ho doped samples show a pinching in the M-H loops with minimum HC.

Suresh, Pittala; Srinath, S.

2014-09-01

380

Structural and magnetic properties of zinc ferrite incorporated in amorphous matrix  

Microsoft Academic Search

Glass ceramics in the (Fe2O3)x·(B2O3)(60?x)·(ZnO)40 (x=17.5 and 20mol%) system were prepared by the melt-quench method and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and magnetization measurements. The samples contain a unique magnetic crystalline phase, the zinc ferrite (ZnFe2O4), embedded in an amorphous matrix. The ZnFe2O4 crystals precipitate during cooling from melting temperature. From the

Petru Pascuta; Adrian Vladescu; Gheorghe Borodi; Eugen Culea; Romulus Tetean

2011-01-01

381

Magnetic properties and superparamagnetism of co-substituted Ni–Zn ferrite nanoparticles  

Microsoft Academic Search

Mixed-ferrite (Ni0.6?xCox)Zn0.4Fe2O4 (x = 0–0.6) particles were synthesized by a co-precipitation method. X-Ray powder diffraction confirms their cubic spinel\\u000a structure. TEM micrographs and XRD calculations showed that the particle size d in the range of 9–29 nm. Magnetic measurements\\u000a reveal superparamagnetic behaviors, with a maximum blocking temperature TB and a relatively high saturation magnetization at x ? 0.2, corresponding to the maximum particle size. Effective

M. M. Eltabey

382

Folate-conjugated luminescent Fe3O4 nanoparticles for magnetic hyperthermia  

NASA Astrophysics Data System (ADS)

We demonstrate a facile approach for the synthesis of folate-conjugated luminescent iron oxide nanoparticles (FLIONs). XRD and TEM analyses reveal the formation of highly crystalline single-phase Fe3O4 nanoparticles of size about 10 nm. The conjugation of folate receptor (folic acid, FA) and luminescent molecule (fluorescein isothiocyanate, FITC) onto the surface of nanoparticles was evident from FTIR and UV-visible spectroscopy. These FLIONs show good colloidal stability, high magnetic field responsivity and excellent self-heating efficacy. Specifically, a new class of magnetic nanoparticles has been fabricated, which can be used as an effective heating source for hyperthermia.

Barick, K. C.; Rana, Suman; Hassan, P. A.

2014-04-01

383

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

384

Illustrating the processability of magnetic layered double hydroxides: layer-by-layer assembly of magnetic ultrathin films.  

PubMed

We report the preparation of single-layer layered double hydroxide (LDH) two-dimensional (2D) nanosheets by exfoliation of highly crystalline NiAl-NO3 LDH. Next, these unilamellar moieties have been incorporated layer-by-layer (LbL) into a poly(sodium 4-styrenesulfonate)/LDH nanosheet multilayer ultrathin film (UTF). Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible light (UV-vis), and X-ray diffraction (XRD) profiles have been used to follow the uniform growth of the UTF. The use of a magnetic LDH as the cationic component of the multilayered architecture enables study of the resulting magnetic properties of the UTFs. Our magnetic data show the appearance of spontaneous magnetization at ?5 K, thus confirming the effective transfer of the magnetic properties of the bulk LDH to the self-assembled film that displays glassy-like ferromagnetic behavior. The high number of bilayers accessible-more than 80-opens the door for the preparation of more-complex hybrid multifunctional materials that combine magnetism with the physical properties provided by other exfoliable layered inorganic hosts. PMID:23621644

Coronado, E; Martí-Gastaldo, C; Navarro-Moratalla, E; Ribera, A; Tatay, S

2013-05-20

385

Magnetic Launcher  

NSDL National Science Digital Library

Students explore electromagnetism and engineering concepts using optimization techniques to design an efficient magnetic launcher. Groups start by algebraically solving the equations of motion for the velocity at the time when a projectile leaves a launcher. Then they test three different launchers, in which the number of coils used is different, measuring the range and comparing the three designs. Based on these observations, students record similarities and differences and hypothesize on the underling physics. They are introduced to Faraday's law and Lenz's law to explain the physics behind the launcher. Students brainstorm how these principals might be applied to real-world engineering problems.

CREAM GK-12 Program, Engineering Education Research Center, College of Engineering and Architecture,

386

Synthesis of magnetic multicomponent nanoparticles CuxNi1-xFe2O4  

NASA Astrophysics Data System (ADS)

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.

Bingölbali, A.; Do?an, N.; Ye?il, Z.; Asiltürk, M.

2015-01-01

387

HRTEM Imaging of Atoms at Sub-Angstrom Resolution  

SciTech Connect

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.

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

2005-04-06

388

Structure and magnetic properties of highly textured nanocrystalline Mn-Zn ferrite thin film  

NASA Astrophysics Data System (ADS)

Nanoparticles of Mn0.2Zn0.8Fe2O4 were chemically synthesized by co-precipitating the metal ions in aqueous solutions in a suitable alkaline medium. The identified XRD peaks confirm single phase spinal formation. The nanoparticle size authentication is carried out from XRD data using Debye Scherrer equation. Thin film fabricated from this nanomaterial by pulse laser deposition technique on quartz substrate was characterized using XRD and Raman spectroscopic techniques. XRD results revealed the formation of high degree of texture in the film. AFM analysis confirms nanogranular morphology and preferred directional growth. A high deposition pressure and the use of a laser plume confined to a small area for transportation of the target species created certain level of porosity in the deposited thin film. Magnetic property measurement of this highly textured nanocrystalline Mn-Zn ferrite thin film revealed enhancement in properties, which are explained on the basis of texture and surface features originated from film growth mechanism.

Joseph, Jaison; Tangsali, R. B.; Pillai, V. P. Mahadevan; Choudhary, R. J.; Phase, D. M.; Ganeshan, V.

2015-01-01

389

Structural, magnetic and electrical properties of Co 1? x Zn x Fe 2O 4 synthesized by co-precipitation method  

Microsoft Academic Search

Nanoparticles of Co1?xZnxFe2O4 with stoichiometric proportion (x) varying from 0.0 to 0.6 were prepared by the chemical co-precipitation method. The samples were sintered at 600°C for 2h and were characterized by X-ray diffraction (XRD), low field AC magnetic susceptibility, DC electrical resistivity and dielectric constant measurements. From the analysis of XRD patterns, the nanocrystalline ferrite had been obtained at pH=12.5–13

I. H. Gul; A. Z. Abbasi; F. Amin; M. Anis-Ur-Rehman; A. Maqsood

2007-01-01

390

Poly-l-lysine-coated magnetic nanoparticles as intracellular actuators for neural guidance  

PubMed Central

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

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

391

Magnetic Nanoparticle Sensors  

PubMed Central

Many types of biosensors employ magnetic nanoparticles (diameter = 5–300 nm) or magnetic particles (diameter = 300–5,000 nm) which have been surface functionalized to recognize specific molecular targets. Here we cover three types of biosensors that employ different biosensing principles, magnetic materials, and instrumentation. The first type consists of magnetic relaxation switch assay-sensors, which are based on the effects magnetic particles exert on water proton relaxation rates. The second type consists of magnetic particle relaxation sensors, which determine the relaxation of the magnetic moment within the magnetic particle. The third type is magnetoresistive sensors, which detect the presence of magnetic particles on the surface of electronic devices that are sensitive to changes in magnetic fields on their surface. Recent improvements in the design of magnetic nanoparticles (and magnetic particles), together with improvements in instrumentation, suggest that magnetic material-based biosensors may become widely used in the future. PMID:22408498

Koh, Isaac; Josephson, Lee

2009-01-01

392

Magnets: Design Guide  

NSDL National Science Digital Library

Provided by the magnet manufacturer Total Magnet Solutions, which offers engineering assistance, stock and custom magnets, and complete magnetic sub-assemblies in prototype to production quantities, the Magnets Design Guide Web page contains a wealth of physical information. Users can read about general categories of permanent magnet functions, magnet materials and their comparisons, units of measure for magnets and their conversion factors, design considerations, finite element analysis, the B-H curve, magnet calculations, and more. A well-designed and attractive site, it provides researchers easy access to practical and informative facts and, at the very least, interesting reading.

2000-01-01

393

Thin Magnetically Soft Wires for Magnetic Microsensors  

PubMed Central

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

Zhukova, Valentina; Ipatov, Mihail; Zhukov, Arcady

2009-01-01

394

Structural and magnetic characterization of La0.8Sr0.2MnO3 nanoparticles prepared via a facile microwave-assisted method  

NASA Astrophysics Data System (ADS)

Nanoparticles of La0.8Sr0.2MnO3 (LSMO) with different particle sizes are synthesized by a very fast, inexpensive, reproducible, and environmentally friendly method: the microwave irradiation of the corresponding mixture of nitrates. The structural and magnetic properties of the samples are investigated by the X-Ray diffraction (XRD), Fourier transform infra-red (FT-IR) spectroscopy, field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and magnetic (DC magnetization and AC susceptibility) measurements. The XRD study coupled with the Rietveld refinement show that all samples crystallize in a rhombohedral structure with the space group of R-3C. The FT-IR spectroscopy and FE-SEM images indicate formation of the perovskite structure of LSMO. The DC magnetization measurements confirm the decrease in the particle size effects on the magnetic properties, e.g. reduction in the ferromagnetic (FM) moment and increase in the surface spin disorder. Magnetic dynamics of the samples studied by AC magnetic susceptibility shows that the magnetic behavior of the nanometer-sized samples is well-described by the Vogel-Fulcher and critical slowing down laws. Strong interaction between magnetic nanoparticles of LSMO was detected by fitting the experimental data with the mentioned models.

Moradi, J.; Ghazi, M. E.; Ehsani, M. H.; Kameli, P.

2014-07-01

395

The magnetization process: Hysteresis  

NASA Technical Reports Server (NTRS)

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.

Balsamel, Richard

1990-01-01

396

Playing with Magnetism  

NSDL National Science Digital Library

This is an activity about magnetism and magnetic forces. Learners will explore objects to which a magnet is attracted or repelled, and investigate the attractive and repulsive forces of two like and two unlike magnetic poles. This is the first activity in the Exploring the Earth's Magnetic Field: An IMAGE Satellite Guide to the Magnetosphere educators guide.

397

A Magnetic Personality  

NSDL National Science Digital Library

Students learn about magnets and how they are formed. They investigate the properties of magnets and how engineers use magnets in technology. Specifically, students learn about magnetic memory storage, which is the reading and writing of data information using magnets, such as in computer hard drives, zip disks and flash drives.

Integrated Teaching And Learning Program

398

Crystal structure, microstructure and magnetic properties of Ni nanoparticles elaborated by hydrothermal route  

NASA Astrophysics Data System (ADS)

We report on the crystal structure, microstructure and magnetic properties of Ni nanoparticles (NPs), with an average diameter of around 40 nm, produced by hydrothermal method. A series of Ni powders was synthesized at relatively low temperature (140 °C) by varying the NaOH concentration. The crystal structure, microstructure and magnetic properties were investigated by means of XRD, MEB coupled to EDX and VSM magnetometry. The XRD patterns show Bragg reflections corresponding to Ni with face centred cubic (fcc) crystal structure. EDX spectra confirm the purity of Ni powders. Moreover, the SEM micrographs show that the Ni-NPs are agglomerated forming entities of 1-5 ?m in average size with different morphologies that change as the NaOH concentration increases. While those entities exhibit a flower-like form at the lowest concentration, a dendritic shape appears for the highest one. The room temperature values for the coercive field (<200 Oe) and saturation magnetization (?52 Am2/kg) were obtained from the magnetic hysteresis loops. We discuss about the influence of the particle morphology on the magnetic behaviour.

Bouremana, A.; Guittoum, A.; Hemmous, M.; Rahal, B.; Sunol, J. J.; Martínez-Blanco, D.; Blanco, J. A.; Gorria, Pedro; Benrekaa, N.

2014-05-01

399

Superconducting magnet  

DOEpatents

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.

Satti, John A. (Naperville, IL)

1980-01-01

400

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)

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.

Habibi, Mohammad Hossein; Mardani, Maryam

2015-02-01

401

The cation inversion and magnetization in nanopowder zinc ferrite obtained by soft mechanochemical processing  

SciTech Connect

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.

Milutinovi?, A. [Institute of Physics, University of Belgrade, Pregrevica 118, Zemun, Belgrade (Serbia); Lazarevi?, Z., E-mail: lzorica@yahoo.com [Institute of Physics, University of Belgrade, Pregrevica 118, Zemun, Belgrade (Serbia); Jovaleki?, ?. [Institute for Multidisciplinary Research, University of Belgrade, Belgrade (Serbia); Kuryliszyn-Kudelska, I. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Rom?evi?, M.; Kosti?, S.; Rom?evi?, N. [Institute of Physics, University of Belgrade, Pregrevica 118, Zemun, Belgrade (Serbia)

2013-11-15

402

Samarium/Cobalt Magnets  

NASA Technical Reports Server (NTRS)

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.

Das, D.; Kumar, K.; Frost, R.; Chang, C.

1985-01-01

403

Magnetism of Carbonados  

NASA Technical Reports Server (NTRS)

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.

Kletetschka, G.; Taylor, P. T.; Wasilewski, P. J.

2000-01-01

404

Structure and magnetic properties of La substituted ZnFe2O4 nanoparticles synthesized by sol-gel autocombustion method  

NASA Astrophysics Data System (ADS)

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.

Masoudpanah, S. M.; Seyyed Ebrahimi, S. A.; Derakhshani, M.; Mirkazemi, S. M.

2014-12-01

405

Thermal and soft magnetic properties of Co40Fe22Ta8B30 glassy particles: In-situ X-ray diffraction and magnetometry studies  

NASA Astrophysics Data System (ADS)

The structural evolution of Co40Fe22Ta8B30 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 Tg. 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 Co40Fe22Ta8B30 glassy particles improves their soft magnetic properties through decreasing the coercivity and increasing the magnetic susceptibility, saturation magnetization, and Curie temperature.

Taghvaei, Amir Hossein; Stoica, Mihai; Kaban, Ivan; Bednar?ik, Jozef; Eckert, Jürgen

2014-08-01

406

Perpendicular magnetic anisotropy of Mn{sub 4}N films on MgO(001) and SrTiO{sub 3}(001) substrates  

SciTech Connect

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.

Yasutomi, Yoko; Ito, Keita; Sanai, Tatsunori; Toko, Kaoru; Suemasu, Takashi, E-mail: suemasu@bk.tsukuba.ac.jp [Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan)

2014-05-07

407

Bio-inspired green synthesis of Fe3O4 spherical magnetic nanoparticles using Syzygium cumini seed extract  

NASA Astrophysics Data System (ADS)

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.

Venkateswarlu, Sada; Natesh Kumar, B.; Prasad, C. H.; Venkateswarlu, P.; Jyothi, N. V. V.

2014-09-01

408

In situ hybridization to chitosan/magnetite nanocomposite induced by the magnetic field  

NASA Astrophysics Data System (ADS)

Chitosan/magnetite nanocomposite was synthesized induced by magnetic field via in situ hybridization in ambient condition. Results of XRD patterns and TEM micrographs indicated that magnetite particles with 10-20 nm were dispersed in chitosan homogeneously. An interesting result is that magnetite nanoparticles were assembled to form chain-like structures under the influence of the external magnetic field, which mimics the magnetite chains inside of magnetotatic bacteria. The saturated magnetization (Ms) of nano-magnetite in chitosan was 50.54 emu/g, which is as high as 54% of bulk magnetite. The remanence (Mr) and coercivity (Hc) were 4 emu/g and14.8 Oe, respectively, which indicated that magnetite nanoparticles were superparamagnetic. The key of route is that a pre-precipitated chitosan hydrogel membrane, used as chemical reactor, which controlled the precipitation of chitosan precipitation and in situ transformation of magnetite from the precursor simultaneously in the magnetic field environment.

Li, Baoqiang; Jia, Dechang; Zhou, Yu; Hu, Qiaoling; Cai, Wei

2006-11-01

409

Structural, magnetic and electrical properties of FexNi100-x/Si(100) films  

NASA Astrophysics Data System (ADS)

A series of FexNi100-x (2?x?100) thin films with thicknesses between 110 and 150 nm were evaporated on Si(100) substrates. The structural, magnetic and electrical properties of the films were studied by means of X-ray diffraction (XRD), Atomic Force Microscopy (AFM), Alternating Gradient Field Magnetometer (AGFM) and four probe-point techniques. It was found that the films are polycrystalline and grow with <111> and <110> textures in the nickel-rich and iron-rich regions, respectively. The crystallite size and the internal strain rate ? were computed vs. the at% Fe using the line profile analysis of a single peak. The study of the magnetization curves shows that all films have an in-plane easy magnetization axis. The saturation magnetization and the coercive field have been studied as a function of the iron atomic percentage. The electric measurements indicate a maximum electrical resistivity of 45 µ? cm near the Anyster composition.

Guechi, N.; Bourzami, A.; Guittoum, A.; Kharmouche, A.; Colis, S.; Meni, N.

2014-05-01

410

Visualizing Magnetic Field Lines  

NSDL National Science Digital Library

In this activity, students take the age old concept of etch-a-sketch a step further. Using iron filings, students begin visualizing magnetic field lines. To do so, students use a compass to read the direction of the magnet's magnetic field. Then, students observe the behavior of iron filings near that magnet as they rotate the filings about the magnet. Finally, students study the behavior of iron filings suspended in mineral oil which displays the magnetic field in three dimensions.

VU Bioengineering RET Program, School of Engineering,

411

Model a Magnet  

NSDL National Science Digital Library

This is a summative activity about magnets. Learners will observe a demonstration of the action of a magnet on a test tube of iron filings, answer questions, and, using the concepts learned in previous activities, write an essay about their understanding of the demonstration. This is the fourth activity in the Mapping Magnetic Influence educators guide. Learners should complete the other three activities in that guide (Seeing Magnetism, What Do You Know about Magnets, and Magnet Map) prior to beginning this activity.

412

What are Magnetic Fields?  

NSDL National Science Digital Library

This is an activity about magnetic fields. Using iron filings, learners will observe magnets in various arrangements to investigate the magnetic field lines of force. This information is then related to magnetic loops on the Sun's surface and the magnetic field of the Earth. This is the second activity in the Magnetic Math booklet; this booklet can be found on the Space Math@NASA website.

413

High Temperature, Permanent Magnet Biased Magnetic Bearings  

E-print Network

The Electron Energy Corporation (EEC) along with the National Aeronautics and Space Administration (NASA) is researching magnetic bearings. The purpose of this research was to design and develop a high-temperature (1000?F) magnetic bearing system...

Gandhi, Varun R.

2010-07-14

414

Exploring Magnetic Fields  

NSDL National Science Digital Library

In this activity, students investigate the presence of magnetic fields around magnets, the sun and the earth. They will explore magnetic field lines, understand that magnetic lines of force show the strength and direction of magnetic fields, determine how field lines interact between attracting and repelling magnetic poles, and discover that the earth and sun have magnetic properties. They will also discover that magnetic force is invisible and that a "field of force" is a region or space in which one object can attract or repel another.

415

The Third Flight Magnet  

NASA Technical Reports Server (NTRS)

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.

McGhee, R. Wayne

1998-01-01

416

Magnetization of ferromagnetic clusters  

SciTech Connect

The magnetization and deflection profiles of magnetic clusters in a Stern-Gerlach magnet are calculated for conditions under which the magnetic moment is fixed in the intrinsic frame of the cluster, and the clusters enter the magnetic field adiabatically. The predicted magnetization is monotonic in the Langevin parameter, the ratio of magnetic energy {mu}{sub 0}B to thermal energy k{sub B}T. In low field the average magnetization is 2/3 of the Langevin function. The high-field moment approaches saturation asymptotically as B{sup {minus}1/2} instead of the B{sup {minus}1} dependence in the Langevin function.

Onishi, Naoki [Univ. of Tokyo (Japan). Inst. of Physics; Bertsch, G. [Univ. of Washington, Seattle, WA (United States); Yabana, Kazuhiro [Niigata Univ. (Japan). Dept. of Physics

1995-02-01

417

Patterned magnetic nanostructures and quantized magnetic disks  

Microsoft Academic Search

Nanofabrication, offering unprecedented capabilities in the manipulation of material structures and properties, opens up new opportunities for engineering innovative magnetic materials and devices, developing ultra-high-density magnetic storage, and understanding micromagnetics. This paper reviews the recent advances in patterned magnetic nanostructures, a fast-emerging field, including (1) state-of-the-art technology for patterning of magnetic nanostructures as small as 10 nm; (2) engineering of

STEPHEN Y. CHOU

1997-01-01

418

Magnet Man: Cool Experiments with Magnets  

NSDL National Science Digital Library

Developed by magnet enthusiast Rick Hoadley, this site for middle and high school students is no-nonsense in style. The explanations and experiments on this page are designed around a series of increasingly more complex issues of magnetism from "What is magnetism?" to "Build your own Gaussmeter" (a device that measures the strength of a magnet). Each experiment is systematically written in clear terms with images for crucial steps.

Hoadley, Rick

2004-08-11

419

Encapsulation of Fe 3O 4 magnetic nanoparticles with poly(methyl methacrylate) via surface functionalized thiol-lactam initiated radical polymerization  

NASA Astrophysics Data System (ADS)

Poly(methyl methacrylate) (PMMA) was grafted onto Fe 3O 4 magnetic nanoparticles (MNPs) by using a thiol-lactam initiated radical polymerization (TLIRP) via grafting from approach. The surface of the MNPs was treated with the (3-mercaptopropyl)trimethoxysilane coupling agent to give thiol functionalized MNPs (MNPs-SH). Subsequently, the polymerization of MMA performed in the presence of the MNPs-SH and butyrolactam efficiently afforded PMMA- g-MNPs. The grafting of PMMA on the surface of the MNPs was investigated by FT-IR, 1H NMR, TGA, XPS, and EDX analyses. The morphology of the core/shell type PMMA- g-MNPs was confirmed by HR-TEM. GPC analysis showed that the molecular weight of PMMA and monomer conversion increased with the reaction time. The amount of the grafted polymer on the surface of the MNPs was found to be ca. 82.5% as estimated from TGA analysis. The MNPs and PMMA- g-MNPs were subjected to magnetic property investigation by SQUID, and the PMMA- g-MNPs showed relatively high saturated magnetization (53.3 emu/g) without any remanence or coercivity, which made the nanocomposites easily separable from solid-liquid phases suggesting their superparamagnetic character. The magnetic nanocomposites had an exceptionally good dispersibility in organic solvents as demonstrated by UV-Vis spectroscopy as well as time-dependent digital photographic monitoring.

Bach, Long Giang; Islam, Md. Rafiqul; Kim, Jong Tae; Seo, SungYong; Lim, Kwon Taek

2012-01-01

420

Magnetic Helicity, Magnetic Energy, and EUV Variability  

Microsoft Academic Search

We estimate the injection rates of magnetic helicity and magnetic energy with data obtained by the Advanced Stokes Polarimeter (ASP) and SOHO\\/MDI. We find that magnetic helicity injected by the photospheric shear motion has a weak correlation with the variability of the EUV intensity, which would be related to sporadic heating of the corona. Three different methodologies to derive the

Y. Sakamoto

2004-01-01

421

Nuclear Magnetic Resonance and Magnetic Field Measurements  

NSDL National Science Digital Library

This laboratory is designed for students to become familiar with the principles and detection techniques of Nuclear Magnetic Resonance (NMR), examine the relationship between current and magnetic field in an electromagnet, and gain experience in the use of magnetic field measurement techniques.

2012-01-04

422

Structural and magnetic properties of quaternary Co2Mn1-xCrxSi Heusler alloy thin films  

Microsoft Academic Search

We present the structural, magnetic, and transport properties of quaternary Co2Mn1-xCrxSi (0 <= x <= 1) Heusler alloy thin films prepared by DC magnetron sputtering on commercially available glass substrates without any buffer layer. Recent theoretical calculations have shown the compositions to be half-metallic. XRD patterns show the presence of L21 structure in the films for x = 0, however,

M. Aftab; G. Hassnain Jaffari; S. K. Hasanain; S. Ismat Shah

2011-01-01

423

Magnetic and transport properties of Cu 2MnAl Heusler alloy prepared by rapidly quenched method  

Microsoft Academic Search

The Cu2MnAl alloy was prepared by rapidly quenched (suction-casting and melt-spinning) methods with various thicknesses of 20, 40 and 1000?m. The X-ray diffraction (XRD) patterns of the fabricated samples show a single phase of Cu2MnAl. All the samples reveal soft magnetic behavior with coercivity below 1.6kA\\/m and Curie temperature of about 600K. Resistance of the alloy behaves as a linear

Do Bang; Nguyen Huy Dan; Nguyen Anh Tuan; Nguyen Xuan Phuc

2007-01-01

424

Structural and magnetic properties of quaternary Co2Mn1-xCrxSi Heusler alloy thin films  

Microsoft Academic Search

We present the structural, magnetic, and transport properties of quaternary Co2Mn1-xCrxSi (0 ? x ? 1) Heusler alloy thin films prepared by DC magnetron sputtering on commercially available glass substrates without any buffer layer. Recent theoretical calculations have shown the compositions to be half-metallic. XRD patterns show the presence of L21 structure in the films for x = 0, however,

M. Aftab; G. Hassnain Jaffari; S. K. Hasanain; S. Ismat Shah

2011-01-01

425

Magnetic and transport properties of Cu2MnAl Heusler alloy prepared by rapidly quenched method  

Microsoft Academic Search

The Cu2MnAl alloy was prepared by rapidly quenched (suction-casting and melt-spinning) methods with various thicknesses of 20, 40 and 1000 mum. The X-ray diffraction (XRD) patterns of the fabricated samples show a single phase of Cu2MnAl. All the samples reveal soft magnetic behavior with coercivity below 1.6 kA\\/m and Curie temperature of about 600 K. Resistance of the alloy behaves

Do Bang; Nguyen Huy Dan; Nguyen Anh Tuan; Nguyen Xuan Phuc

2007-01-01

426

Preparation and properties of hybrid monodispersed magnetic ?-Fe 2O 3 based chitosan nanocomposite film for industrial and biomedical applications  

Microsoft Academic Search

In this study, hydrothermally prepared magnetic ?-Fe2O3 nanoparticles were dispersed in chitosan (CH) solution to fabricate nanocomposite film. X-ray diffraction (XRD) patterns indicated that the ?-Fe2O3 nanoparticles were pure ?-Fe2O3 with rhombohedral structures, and the fabrication of CH did not result in a phase change. The scanning electron microscopy (SEM) and transmission electron microscope (TEM) results showed that the hexagonal

Jay Singh; M. Srivastava; Joydeep Dutta; P. K. Dutta

2011-01-01

427

Diluted magnetic semiconductor properties in Zn 1?x Cu x O nanoparticles synthesized by sol gel route  

Microsoft Academic Search

Nanoparticles of ZnO:Cu Diluted Magnetic Semiconductor (DMS) are prepared using sol gel method. The structural, optical and\\u000a EPR properties of them are investigated. The XRD patterns of them show the formation of polycrystalline and hexagonal wurtzite\\u000a structure without any secondary phase formation. The average size of particles ranges from 14 to 19 nm. In the optical absorption\\u000a study of the samples,

R. Elilarassi; P. Sambasiva Rao; G. Chandrasekaran

2011-01-01

428

ZnO based diluted magnetic semiconductor thin films by RF magnetron sputtering for spin photonic devices  

Microsoft Academic Search

Transition metal (TM) doped ZnO is a promising diluted magnetic semiconductor (DMS) material for the fabrication of spintronics devices. In this paper, we have investigated Mn and Cr doped ZnO thin films grown by RF magnetron sputtering. The films grown on Si(100) and sapphire (Al2O3) have been characterized by X-ray diffraction (XRD) and Vibrating Sample Magnetometer (VSM) to know its

J. Elanchezhiyan; K. P. Bhuvana; N. Gopalakrishnan; T. Balasubramanian

2007-01-01

429

Effect of substrate on magnetic properties of La2/3Sr1/3MnO3 films  

NASA Astrophysics Data System (ADS)

A comparative study of La2/3Sr1/3MnO3 (LSMO) films of thickness 50nm deposited on MgO(100) and STO(100) substrates using Pulsed Laser Deposition (PLD) is presented. XRD patterns confirm the epitaxial nature of both the films. Magnetic measurements with in-plane field show that coercivity of the film deposited on MgO substrate is 3-4 times higher than that deposited on STO substrate.

Prajapat, C. L.; Bhattacharya, D.; Tokas, R. B.; Roul, B. K.; Singh, M. R.; Mishra, P. K.; Basu, S.; Gupta, S. K.; Ravikumar, G.

2013-02-01

430

Magnetic properties related to structure and complete composition analyses of nanocrystalline La 1? x Mn 1? y O 3 powders  

Microsoft Academic Search

Structural and magnetic properties were studied on La1?xMnO3±? nanocrystalline powders exhibiting different La\\/Mn ratios. These compounds were prepared using a gel combustion method based on a cation solution soaking by acrylamide polymerization. Structural properties were studied both by transmission electron microscopy and X-ray diffraction (XRD). Complete chemical composition analyses were performed by induced coupled plasma spectroscopy and by iodometric titration.

G. Dezanneau; A. Sin; H. Roussel; M. Audier; H. Vincent

2003-01-01

431

The Speciation of Arsenic in Iron Oxides in Mine Wastes from the Giant Gold Mine, N.W.T.: Application of Synchrotron Micro-XRD and Micro-XANES at the Grain Scale  

SciTech Connect

Understanding the solid-phase speciation of arsenic in soils and sediments is important in evaluations of the potential mobility of arsenic and of its bio-availability in the environment. This is especially true in mine-influenced environments, where arsenic commonly is present at concentrations two and three orders of magnitude above quality criteria for soils and sediments. Arsenic-bearing particulates dispersed through hydraulic transport or aerosol emissions can represent a persistent source of contamination in sediments and soils adjacent to past mining and metallurgical operations. The stability and mobility of arsenic associated with these phases depend on the chemical form and oxidation state of the arsenic and the interaction with post-depositional geochemical conditions. The Giant mine in Yellowknife, Northwest Territories, roasted arsenic-bearing gold ore from 1949 to 1999. The roasting process decomposed arsenic-bearing sulfides (pyrite and arsenopyrite) to produce a calcine containing fine (generally <50 {micro}m) arsenic-bearing iron oxides. We have applied synchrotron As K-edge micro X-ray Absorption Near-Edge Structure ({micro}XANES) and {micro}XRD as part of a grain-by-grain mineralogical approach for the direct determination of the host mineralogy and oxidation state of As in these roaster-derived iron oxides. The grain-scale approach has resolved potential ambiguities that would have existed had only bulk XANES and XRD methods been applied. Using combined optical microscopy, electron microprobe and {micro}XRD, we have determined that the roaster-iron oxides are nanocrystalline grains of maghemite containing <0.5 to 7 wt.% As. Some of these arsenic-bearing nanocrystalline grains are a mixture of maghemite and hematite. All roaster iron oxides, including those present in 50-year-old tailings, contain mixtures of As{sup 5+} and As{sup 3+}. The persistence of As{sup 3+} in roaster-derived maghemite in shallow subareal (oxidized) shoreline tailings for over 50 years suggests that the arsenic is relatively stable under these conditions, even though As{sup 3+} is a reduced form of arsenic, and maghemite is normally considered a metastable phase.

Walker,S.; Jamieson, H.; Lanzirotti, A.; Andrade, C.; Hall, G.

2005-01-01

432

Synthesis of magnetic FexOy@silica-pillared clay (SPC) composites via a novel sol-gel route for controlled drug release and targeting.  

PubMed

Novel magnetic silica-pillared clay (SPC) materials with an ordered interlayered mesopore structure were synthesized via a two-step method including gallery molecular self-assembly and sol-gel magnetic functionalization, resulting in the formation of FexOy@SPC composites. Small-angle XRD, TEM and N2 adsorption-desorption isotherms results show that these composites conserved a regular layered and ordered mesoporous structure after the formation of FexOy nanoparticles. Wide-angle XRD and XPS analyses confirmed that the FexOy generated in these mesoporous silica-pillared clay hosts is mainly composed of ?-Fe2O3. Magnetic measurements reveal that these composites with different ?-Fe2O3 loading amounts possess super-paramagnetic properties at 300K, and the saturation magnetization increases with increasing Fe ratio loaded. Compared to the pure SPC, the in vitro drug release rate of the FexOy@SPC composites was enhanced due to the fact that the intensities of the SiOH bands on the pore surface of SPC decrease after the generation of FexOy. However, under an external magnetic field of 0.15T, the drug release rate of the FexOy@SPC composites decreases dramatically owing to the aggregation of the magnetic FexOy@SPC particles triggered by non-contact magnetic force. The obtained FexOy@SPC composites imply the possibility of application in magnetic drug targeting. PMID:24857471

Mao, Huihui; Liu, Xiaoting; Yang, Jihe; Li, Baoshan; Yao, Chao; Kong, Yong

2014-07-01

433

Influence of spherical assembly of copper ferrite nanoparticles on magnetic properties: orientation of magnetic easy axis.  

PubMed

The magnetic properties of copper ferrite (CuFe2O4) nanoparticles prepared via sol-gel auto combustion and facile solvothermal method are studied focusing on the effect of nanoparticle arrangement. Randomly oriented CuFe2O4 nanoparticles (NP) are obtained from the sol-gel auto combustion method, while the solvothermal method allows us to prepare iso-oriented uniform spherical ensembles of CuFe2O4 nanoparticles (NS). X-ray diffractometry (XRD), atomic absorption spectroscopy (AAS), infra-red (IR) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), (57)Fe Mössbauer spectroscopy and vibrating sample magnetometer (VSM) are used to investigate the composition, microstructure and magnetic properties of as-prepared ferrite nanoparticles. The field-dependent magnetization measurement for the NS sample at low temperature exhibits a step-like rectangular hysteresis loop (M(R)/M(S) ~ 1), suggesting cubic anisotropy in the system, whereas for the NP sample, typical features of uniaxial anisotropy (M(R)/M(S) ~ 0.5) are observed. The coercive field (HC) for the NS sample shows anomalous temperature dependence, which is correlated with the variation of effective anisotropy (K(E)) of the system. A high-temperature enhancement of H(C) and K(E) for the NS sample coincides with a strong spin-orbit coupling in the sample as evidenced by significant modification of Cu/Fe-O bond distances. The spherical arrangement of nanocrystals at mesoscopic scale provokes a high degree of alignment of the magnetic easy axis along the applied field leading to a step-like rectangular hysteresis loop. A detailed study on the temperature dependence of magnetic anisotropy of the system is carried out, emphasizing the influence of the formation of spherical iso-oriented assemblies. PMID:24714977

Chatterjee, Biplab K; Bhattacharjee, Kaustav; Dey, Abhishek; Ghosh, Chandan K; Chattopadhyay, Kalyan K

2014-06-01

434

Effects of substitutions M on the formation, structure and magnetic properties of Sm 2Fe 15M 2C 2 (M = V, Cr, Ti, Nb, Zr, Mn and Mo) compounds  

Microsoft Academic Search

The effects of substitutions M on the formation, structure and magnetic properties of Sm2Fe15M2C2 (M = V, Cr, Ti, Nb, Zr, Mn and Mo) compounds have been systematically studied using XRD, magnetic and Mössbauer measurements. It has been found that V, Cr, Ti, Nb and Zr can help to form the 2 : 17 carbides, with a certain amount of

Zhongmin Chen; G. C. Hadjipanayis; M. Daniel; M. Digas; A. Moukarika; V. Papaefthymiou

1998-01-01

435

Effects of substitutions M on the formation, structure and magnetic properties of Sm2Fe15M2C2 (M = V, Cr, Ti, Nb, Zr, Mn and Mo) compounds  

Microsoft Academic Search

The effects of substitutions M on the formation, structure and magnetic properties of Sm2Fe15M2C2 (M = V, Cr, Ti, Nb, Zr, Mn and Mo) compounds have been systematically studied using XRD, magnetic and Mössbauer measurements. It has been found that V, Cr, Ti, Nb and Zr can help to form the 2 : 17 carbides, with a certain amount of

M. Daniel; M. Digas; A. Moukarika; V. Papaefthymiou; Z. Chen; G. C. Hadjipanayis

1998-01-01

436

Structural properties of ultrafine Ba-hexaferrite nanoparticles  

NASA Astrophysics Data System (ADS)

Crystal structure of ultrafine Ba-hexaferrite (BaFe12O19) nanoparticles was studied using X-ray diffractometry (XRD), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDXS), X-ray absorption fine structure (XAFS), and Mössbauer spectroscopy (MS), to be compared to the structure of larger nanoparticles and the bulk. The nanoparticles were synthesized with hydrothermal treatment of an appropriate suspension of Ba and Fe hydroxides in the presence of a large excess of OH-. The ultrafine nanoparticles were formed in a discoid shape, ?10 nm wide and only ?3 nm thick, comparable to the size of the hexagonal unit cell in the c-direction. The HRTEM image analysis confirmed the hexaferrite structure, whereas EDXS showed the composition matching the BaFe12O19 formula. XAFS and MS analyses showed considerable disorder of the structure, most probably responsible for the low magnetization.

Makovec, Darko; Primc, Darinka; Šturm, Sašo; Kodre, Alojz; Hanžel, Darko; Drofenik, Miha

2012-12-01

437

Structural and magnetic properties of Sr2FeMoO6 film prepared by electrophoresis technique  

NASA Astrophysics Data System (ADS)

Double perovskite Sr2FeMoO6 film was fabricated by electrophoresis method on single crystal Si substrate. The post-annealing treatment was carried out at 900 °C, 960 °C, 1060 °C and 1100 °C with 5% H2/Ar atmosphere. Surface micrograph, structural and magnetic properties of the film have been investigated. It is found that the annealing temperature plays an important role on the phase formation and magnetic properties. According to X-ray diffraction (XRD), single phase Sr2FeMoO6 film was obtained at annealing temperature 1100 °C, the film shows typical polycrystal property. However, the superstructure reflection assigning the ordering arrangement of Fe and Mo atoms in the perovskite structure disappears in our XRD pattern. Raman detection finds two peaks at around 440 cm-1 and 620 cm-1, which belongs to Sr2FeMoO6 phase. Consistent with XRD results, typical impurity like SrMoO4 appears at around 880 cm-1 in the film annealed at lower temperature. Microstructure investigation shows that the surface of the film is homogeneous and the grain size of particles increases with annealing temperature. Temperature dependence of magnetization reveal that the highest Curie temperature (TC=282 K) is obtained from the film annealed at 1100 °C. Owing to the large amount of anti-site defect, the highest TC is still lower than that of parent Sr2FeMoO6 powder.

Zhang, Q.; Xu, Z. F.; Liang, J.; Pei, J.; Sun, H. B.

2014-03-01

438

Texture determination by energy-dispersive XRD  

NASA Astrophysics Data System (ADS)

Energy-dispersive X-ray diffraction using synchrotron radiation has a number of advantages for determination of crystallographic texture, and we present an instrument for use on Station 16.4 of the Daresbury SRS, designed primarily for texture studies on surface layers. The instrument allows measurement at low angles of incidence to enhance surface sensitivity. It can typically acquire texture information at 176 ( ?, ?) orientation points in around 2 h, and provides a complete set of pole figures simultaneously.

Player, M. A.; Shi, Z.; Clark, S. M.; Miller, M. C.; Tang, C. C.

1998-06-01

439

Designing magnets with prescribed magnetic fields  

NASA Astrophysics Data System (ADS)

We present a novel design method capable of finding the magnetization densities that generate prescribed magnetic fields. The method is based on the solution to a simple variational inequality and the resulting designs have simple piecewise-constant magnetization densities. By this method, we obtain new designs of magnets that generate commonly used magnetic fields: uniform magnetic fields, self-shielding fields, quadrupole fields and sextupole fields. Further, it is worth noting that this method is not limited to the presented examples, and in particular, three-dimensional designs can be constructed in a similar manner. In conclusion, this novel design method is anticipated to have broad applications where specific magnetic fields are important for the performance of the devices.

Liu, Liping

2011-03-01

440

Preparation and characterization of magnetic TiO 2 nanoparticles and their utilization for the degradation of emerging pollutants in water  

Microsoft Academic Search

Magnetic TiO2\\/Fe3O4 and TiO2\\/SiO2\\/Fe3O4 nanoparticles (NPs) were prepared by an ultrasonic-assisted sol–gel method using a commercial nanosized magnetic iron oxide as a support. Magnetic NPs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption (BET surface area) and SQUID magnetometer. Structure analyses indicated that TiO2\\/Fe3O4 NPs presented a core–shell structure with a TiO2 (anatase) coating wrapped around

Pedro M. Álvarez; Josefa Jaramillo; Francisco López-Piñero; Pawel K. Plucinski

2010-01-01

441

Structural and magnetic properties of Co{sub 2}Ti{sub 1?x}Fe{sub x}Al (0 ? x ? 0.5) alloys  

SciTech Connect

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.

Pal, Lakhan, E-mail: lakhanbainsla@gmail.com; Gupta, Sachin, E-mail: lakhanbainsla@gmail.com; Suresh, K. G., E-mail: lakhanbainsla@gmail.com [Department of Physics, Indian Institute of Technology Bombay, Mumbai-400076 (India)

2014-04-24

442

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

Azodye-rhodamine hybrid colorimetric fluorescent probe () has been designed and synthesized. The structure of 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 () 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

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

2015-02-01

443

Study of inclusion complex between 2,6-dinitrobenzoic acid and ?-cyclodextrin by 1H NMR, 2D 1H NMR (ROESY), FT-IR, XRD, SEM and photophysical methods  

NASA Astrophysics Data System (ADS)

The formation of host-guest inclusion complex of 2,6-dinitrobenzoic acid (2,6-DNB) with nano-hydrophobic cavity of ?-cyclodextrin (?-CD) in solution phase has been studied by UV-visible spectroscopy and electrochemical analysis (cyclic voltammetry, CV). The effect of acid-base concentrations of 2,6-DNB has been studied in presence and absence of ?-CD to determination for the ground state acidity constant (pKa). The binding constant of inclusion complex at 303 K was calculated using Benesi-Hildebrand plot and thermodynamic parameter (?G) was also calculated. The solid inclusion complex formation between ?-CD and 2,6-DNB was confirmed by 1H NMR, 2D 1H NMR (ROESY), FT-IR, XRD and SEM analysis. A schematic representation of this inclusion process was proposed by molecular docking studies using patch dock server.

Srinivasan, Krishnan; Stalin, Thambusamy

2014-09-01

444