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1

Evidence from HRTEM image processing, XRD and EDS on nanocrystalline iron-doped titanium oxide powders  

Microsoft Academic Search

We investigated nanosized iron-doped TiO2 in the presence of poly(ethylene glycol) (PEG), synthesised by modified sol–gel method, by transmission electron microscopy (TEM), selected area electron diffraction (SAED), high-resolution electron microscopy (HRTEM), HRTEM image processing, energy dispersive X-ray analysis (EDS) and X-ray diffraction (XRD). XRD of as prepared sample showed very broad diffraction maxima of anatase as the dominant phase and

A. M. Tonejc; I. Djerdj

2001-01-01

2

Comparison of structural parameters of PF carbon from XRD and HRTEM techniques  

Microsoft Academic Search

A new technique to obtain structural parameters Lc, La and d, of phenol formaldehyde resin char (PFC) from TEM images has been developed. Similar structural parameters were also obtained from XRD technique and a comprehensive comparison of the results from the two techniques was made. The present study shows a good agreement between the results from the two techniques. The

Atul Sharma; Takashi Kyotani; Akira Tomita

2000-01-01

3

Structural and chemical characterization of synthetic (Na,K)-richterite solid solutions by EMP, HRTEM, XRD and OH-valence vibrational spectroscopy  

Microsoft Academic Search

The composition and structure of synthetic (Na,K)-richterites have been characterized by EMP, HRTEM, XRD and FTIR methods.\\u000a Despite the fact that the syntheses were done on bulk compositions along the richterite-K-richterite binary, EMP analyses\\u000a and FTIR spectra indicate that the amphiboles are not simple solid solutions of the two richterite endmembers richterite and\\u000a K-richterite alone, but tremolite and Mg-cummingtonite components

M. Gottschalk; M. Andrut

1998-01-01

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

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

6

Combined XRD and XAS  

SciTech Connect

X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) are complementary techniques for investigating the structure of materials. XRD probes long range order and XAFS probes short range order. We have combined the two techniques at one synchrotron beamline, X18A at the NSLS, allowing samples to be studied in a single experiment. This beamline will allow for coordinated measurements of local and long range structural changes in chemical transformations and phase transitions using both techniques.

Ehrlich, S.N.; Hanson, J.C.; Lopez Camara, A.; Barrio, L.; Estrella, M.; Zhou, G.; Si, R.; Khalid, S. & Wang, Q.

2010-11-24

7

Structural analysis of PVC and PFA carbons prepared at 500–1000 °C based on elemental composition, XRD, and HRTEM  

Microsoft Academic Search

Temperature programmed oxidation (TPO) method to evaluate the structure of carbonaceous materials was proposed in the previous paper, and this method was applied to analyze two sets of carbons derived from PVC and PFA in the temperature range of 500–1000 °C. Amounts of H2O, CO and CO2 evolved during oxidation were accurately determined, and they were used to estimate an

Hiromi Aso; Koichi Matsuoka; Atul Sharma; Akira Tomita

2004-01-01

8

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

9

A new quantitative approach for microstructural analysis of coal char using HRTEM images  

Microsoft Academic Search

HRTEM is a useful technique to observe the structure of coal char at an atomic level. To analyze the char structure quantitatively, we developed a new filtration technique for HRTEM images and a computer algorithm to obtain information such as the graphene layer size, interlayer spacing, the number of layers per stack, and its distribution from the post-filtered extracted HRTEM

A. Sharma; T. Kyotani; A. Tomita

1999-01-01

10

Survey of basic XRD applications.  

SciTech Connect

This 1/2 day workshop will survey various applications of XRD analysis, including in-situ analyses and neutron diffraction. The analyses will include phase ID, crystallite size and microstrain, preferred orientation and texture, lattice parameters and solid solutions, and residual stress. Brief overviews of high-temperature in-situ analysis, neutron diffraction and synchrotron studies will be included.

Rodriguez, Mark Andrew

2010-07-01

11

Synthesis and magnetic characterizations of uniform iron oxide nanoparticles  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

12

Structural and magnetic properties of Ni doped CeO2 nanoparticles.  

PubMed

We report room temperature ferromagnetism in Ni doped CeO2 nanoparticles using X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), and dc magnetization measurements. Nanoparticles of Ce(1-x)Ni(x)O2 (0.0 < or = x < or = 0.10) were prepared by using a co-precipitation method. XRD measurements indicate that all samples exhibit single phase nature with cubic structure and ruled out the presence of any secondary phase. Lattice parameters, strain and particle size calculated from XRD data have been found to decrease with increase in Ni doping. Inter-planner distance measured from HR-TEM images for different Ni doped samples indicate that Ni ions are substituting Ce ions in CeO2 matrix. Magnetization measurements performed at room temperature display weak ferromagnetic behavior of Ce(1-x)Ni(x)O2 (0.0 < or = x < or = 0.10) nanoparticles. Magnetic moment calculated from magnetic hysteresis loop was found to increases with Ni doping up to 7% and then start decreasing with further doping. PMID:21137898

Kumar, Shalendra; Kim, Young Joo; Koo, B H; Lee, Chan Gyu

2010-11-01

13

HRTEM at half-Angstrom resolution: From OAM to TEAM  

SciTech Connect

Transmission electron microscopy (TEM) at sub-Angstrom resolution is important for nanotechnology. Identifying atom positions requires appropriate resolution, the ability to separate distinct objects in images. With Cs corrected, the information limit of the TEM controls resolution. The OAM has demonstrated that a resolution of 0.78A is possible. The TEAM (transmission electron achromatic microscope) will be a TEM using hardware correction of Cs with a monochromator to improve its information limit beyond that of the OAM by improvement of the electron-beam energy spread. It is shown that A 300keV HRTEM TEAM does not require a Cc corrector to reach 0.5A as long as beam energy spread and objective-lens current ripple are lowered sufficiently. A lower-voltage TEAM will require stricter limits on objective-lens current ripple to reach the targeted 0.5A resolution. No improvement in HT ripple or noise is required to improve the information limit per se since the monochromator determines the energy spread in the beam. However, improved HT ripple and noise will improve the beam current statistics (number of electrons passing through the monochromator) by placing more of the electrons closer to the center of the energy-spread distribution

O'Keefe, Michael A.

2003-02-17

14

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

15

Rock magnetism investigation of highly magnetic soil developed on calcareous rock in Yun-Gui Plateau, China: Evidence for pedogenic magnetic minerals  

NASA Astrophysics Data System (ADS)

Detailed rock-magnetic and pedological analyses were conducted on the highly magnetic soils developed on calcareous rocks in the Yun-Gui Plateau of west-southern China in order to characterize its particular magnetic characteristics and pedogenesis of magnetic minerals. The magnetic concentration and mineralogy in the soils were determined by rock magnetism, powder X-ray diffraction and high resolution transmission electron microscope (HRTEM) with the energy dispersive X-ray analysis (EDX). The highly magnetic soils contained characteristics of highly weathered soils with a hue of 2.5YR, dominantly gibbsite-sesquioxide mineralogy, low organic matter content and high clay and free iron (Fed) content. Soil magnetic susceptibility (?lf) ranged from 2000 × 10 - 8 to 6000 × 10 - 8 m 3 kg - 1 ; but in some layers it exceeded 6000 × 10 - 8 or 6500 × 10 - 8 m 3 kg - 1 , which was the highest magnetic soils so far found in the world. Magnetic measurements indicated that the frequency-dependent susceptibility (?lf - ?hf) ranged from 210 × 10 - 8 to 720 × 10 - 8 m 3 kg - 1 , suggesting the presence of abundant ultrafine magnetic grains. High-temperature magnetization ( M- T) identified the magnetic carriers as maghemite and magnetite with a Curie point ( Tc) at about 230 °C and 580 °C, respectively. XRD patterns showed that the gibbsite and hematite were main clay minerals in these highly weathered soils. HRTEM/EDX analysis showed that the pedogenic nano-scale magnetite/maghemite were responsible for the high magnetic susceptibility value of the soil. These particles varied from 20 to 100 nm in size and exhibited well crystalline nanoparticles. Magnetic enhancement in the soil profile was due to increased concentration of pedogenic superparamagnetic (SP) ferrimagnetic minerals upon pedogenesis. This study provided a strong evidence for the evolution of pedogenic magnetic minerals in the soils formed on non-magnetic parent materials. The identification in magnetic properties and mineralogy of the highly magnetic soils has significance for pedoenvironmental implications.

Lu, S. G.; Chen, D. J.; Wang, S. Y.; Liu, Y. D.

2012-02-01

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

Interfacial magnetic coupling between Fe nanoparticles in Fe-Ag granular alloys  

NASA Astrophysics Data System (ADS)

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.

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.

2012-01-01

18

High Resolution Transmission Electron Microscopy (HRTEM) of Nanophase Ferric Oxides.  

National Technical Information Service (NTIS)

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 Ma...

D. C. Golden R. V. Morris D. W. Ming H. V. Lauer

1994-01-01

19

Surface effects in the magnetic properties of crystalline 3 nm ferrite nanoparticles chemically synthesized  

NASA Astrophysics Data System (ADS)

We have systematically studied the magnetic properties of ferrite nanoparticles with 3, 7, and 11 nm of diameter with very narrow grain size distributions. Samples were prepared by the thermal decomposition of Fe(acac)3 in the presence of surfactants giving nanoparticles covered by oleic acid. High resolution transmission electron microscopy (HRTEM) images and XRD diffraction patterns confirms that all samples are composed by crystalline nanoparticles with the spinel structure expected for the iron ferrite. ac and dc magnetization measurements, as well in-field Mössbauer spectroscopy, indicate that the magnetic properties of nanoparticles with 11 and 7 nm are close to those expected for a monodomain, presenting large MS (close to the magnetite bulk). Despite the crystalline structure observed in HRTEM images, the nanoparticles with 3 nm are composed by a magnetically ordered region (core) and a surface region that presents a different magnetic order and it contains about 66% of Fe atoms. The high saturation and irreversibility fields in the M(H) loops of the particles with 3 nm together with the misalignment at 120 kOe in the in-field Mössbauer spectrum of surface component indicate a high surface anisotropy for the surface atoms, which is not observed for the core. For T<10 K, we observe an increase in the susceptibility and of the magnetization for former sample, indicating that surface moments tend to align with applied field increasing the magnetic core size.

Lima, E.; de Biasi, E.; Mansilla, M. Vasquez; Saleta, M. E.; Effenberg, F.; Rossi, L. M.; Cohen, R.; Rechenberg, H. R.; Zysler, R. D.

2010-11-01

20

Structure, morphology and magnetic properties of Fe Au core-shell nanoparticles  

NASA Astrophysics Data System (ADS)

The aim of the present work is the investigation of the core-shell Fe@Au nanoparticles obtained by the inverse micelles method. Also hybrid structures between Fe@Au nanoparticles and the well-known conducting polymer polypyrrole (PPY) were obtained and investigated. The properties of the composites were investigated by TEM, HRTEM, X-ray diffraction (XRD), X-ray Photoelectron spectroscopy (XPS) and magnetization measurements. The TEM, HRTEM measurements show that two categories of core-shell nanoparticles with mean diameters of 5 nm and 25 nm, respectively, are formed. The XPS investigations of the core-shell Fe@Au nanoparticles indicate that besides Fe 0 inside the cores, small amounts of Fe II,III, located onto the gold surface ,were also formed during the samples preparation. The magnetization of the investigated nanocomposites measured versus increasing and decreasing magnetic field shows no hysteresis loop, this behavior being consistent with a superparamagnetic behavior. The behavior of the SQUID magnetization vs. temperature under field cooled (FC) and zero field cooled (ZFC) at 0.1 T magnetic field for Fe@Au nanoparticles confirmed the existence of superparamagnetism. The superparamagnetic model was used to fit the experimental magnetization vs. applied magnetic field as it was measured by SQUID up to 5 T.

Pana, O.; Teodorescu, C. M.; Chauvet, O.; Payen, C.; Macovei, D.; Turcu, R.; Soran, M. L.; Aldea, N.; Barbu, L.

2007-09-01

21

Comparative investigation of NiO nano- and microstructures for structural, optical and magnetic properties  

NASA Astrophysics Data System (ADS)

Nickel oxide (NiO) nano- and microstructures were synthesized by the microwave combustion method (MCM) and the conventional combustion method (CCM) using urea as the fuel. The as-synthesized NiO powders were characterized by X-ray powder diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), high resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, Brunauer-Emmett-Teller (BET) analysis and vibrating sample magnetometer (VSM) analysis. The XRD results confirmed the formation of cubic phase NiO. The formation of NiO nano- and microstructures were confirmed by HR-SEM and HR-TEM and their possible formation mechanisms were also proposed. The optical absorption and photoluminescence emissions were determined by DRS and PL spectra respectively. The band gap was measured using the Kubelka-Munk model and it shows 3.36 eV for NiO (MCM) and 2.70 eV for NiO (CCM). The magnetic properties of the synthesized NiO nano- and microstructures were investigated with a vibrating sample magnetometer (VSM) and their hysteresis loops were obtained at room temperature. The relatively high saturation magnetization (21.22 emu/g) of NiO-MCM shows that it is ferromagnetic and low saturation magnetization (7.43 emu/g) of NiO-CCM confirms the superparamagnetic behavior.

Manikandan, A.; Judith Vijaya, J.; John Kennedy, L.

2013-03-01

22

A new AFM-HRTEM combined technique for probing isolated carbon nanotubes  

Microsoft Academic Search

A new technique has been developed for characterizing individual carbon nanotubes (CNTs). This technique combines atomic force microscopy (AFM) measurements with an independent determination of the CNT structure obtained by using thin carbon grid membranes for high-resolution transmission electron microscopy (HRTEM) measurements. The membrane grids are easily transferred onto silicon oxide substrates, where they are observed by AFM and an

Shota Kuwahara; Toshiki Sugai; Hisanori Shinohara

2009-01-01

23

A new AFM-HRTEM combined technique for probing isolated carbon nanotubes.  

PubMed

A new technique has been developed for characterizing individual carbon nanotubes (CNTs). This technique combines atomic force microscopy (AFM) measurements with an independent determination of the CNT structure obtained by using thin carbon grid membranes for high-resolution transmission electron microscopy (HRTEM) measurements. The membrane grids are easily transferred onto silicon oxide substrates, where they are observed by AFM and an optical charged-coupled device. Electrostatic force microscopy measurements are also performed on single- and double-walled CNTs whose structures had previously been determined by HRTEM. The results reveal that the diameter and outer tube length have a greater effect on determining the capacitance of the nanotubes than the presence of the inner tube of double-walled CNTs. PMID:19436091

Kuwahara, Shota; Sugai, Toshiki; Shinohara, Hisanori

2009-06-01

24

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

25

Pore Structure and Fractal Characteristics of Activated Carbon Fibers Characterized by Using HRTEM  

Microsoft Academic Search

The pore microstructures in two viscouse rayon-based ACF samples were characterized by nitrogen adsorption and HRTEM. For TEM, a two-dimensional fast Fourier transform (FFT) of the original TEM images was performed, and pores in different size ranges were extracted by the inverse FFT (IFFT) operation. The surface fractal dimensions of the samples were evaluated by using both N2 adsorption and

Zheng-Hong Huang; Feiyu Kang; Wen Lai Huang; Jun-Bing Yang; Kai-Ming Liang; Meng-Long Cui; Zhiying Cheng

2002-01-01

26

Atom by atom: HRTEM insights into inorganic nanotubes and fullerene-like structures  

PubMed Central

The characterization of nanostructures down to the atomic scale is essential to understand some physical properties. Such a characterization is possible today using direct imaging methods such as aberration-corrected high-resolution transmission electron microscopy (HRTEM), when iteratively backed by advanced modeling produced by theoretical structure calculations and image calculations. Aberration-corrected HRTEM is therefore extremely useful for investigating low-dimensional structures, such as inorganic fullerene-like particles and inorganic nanotubes. The atomic arrangement in these nanostructures can lead to new insights into the growth mechanism or physical properties, where imminent commercial applications are unfolding. This article will focus on two structures that are symmetric and reproducible. The first structure that will be dealt with is the smallest stable symmetric closed-cage structure in the inorganic system, a MoS2 nanooctahedron. It is investigated by means of aberration-corrected microscopy which allowed validating the suggested DFTB-MD model. It will be shown that structures diverging from the energetically most stable structures are present in the laser ablated soot and that the alignment of the different shells is parallel, unlike the bulk material where the alignment is antiparallel. These findings correspond well with the high-energy synthetic route and they provide more insight into the growth mechanism. The second structure studied is WS2 nanotubes, which have already been shown to have a unique structure with very desirable mechanical properties. The joint HRTEM study combined with modeling reveals new information regarding the chirality of the different shells and provides a better understanding of their growth mechanism.

Sadan, Maya Bar; Houben, Lothar; Enyashin, Andrey N.; Seifert, Gotthard; Tenne, Reshef

2008-01-01

27

Pore structure and fractal characteristics of activated carbon fibers characterized by using HRTEM.  

PubMed

The pore microstructures in two viscouse rayon-based ACF samples were characterized by nitrogen adsorption and HRTEM. For TEM, a two-dimensional fast Fourier transform (FFT) of the original TEM images was performed, and pores in different size ranges were extracted by the inverse FFT (IFFT) operation. The surface fractal dimensions of the samples were evaluated by using both N(2) adsorption and TEM image analysis. The results show that TEM can portray the shapes of the pore, and it can give a quantitative evaluation of surface irregularity that is consistent with nitrogen adsorption results. PMID:16290620

Huang, Zheng-Hong; Kang, Feiyu; Huang, Wen Lai; Yang, Jun-Bing; Liang, Kai-Ming; Cui, Meng-Long; Cheng, Zhiying

2002-05-15

28

Shape-controlled synthesis and magnetic properties of FePt nanocubes  

NASA Astrophysics Data System (ADS)

In this research, FePt nanocubes, octapods and polyhedra were successfully prepared with Mo(Co)6 as a reducing agent. The chemically-synthesized cubic FePt nanoparticles could easily be self-assembled into an oriented nanoarray. These ordered nanomagnet arrays were expected to achieve high-density information storage and high performance in permanent magnets. The self-assembed FePt nanocubes were chemically disordered with a face centered cubic (fcc) structure. During annealing, these particles changed to a face-centered tetragonal (fct) order. The phase structure, the micro-morphology and magnetic properties were characterized by using X-ray diffraction (XRD), High resolution transmission electron microscope (HRTEM), Scanning electron microscope (SEM) and vibrating sample magnetometer (VSM).

Zhou, Mingge; Li, Wei; Zhu, Minggang; Zhou, Dong; Hou, Yanglong

2013-08-01

29

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

30

XRD and HREM studies of nanocrystalline Cu and Pd.  

National Technical Information Service (NTIS)

Consolidated powders of nanocrystalline Cu and Pd have been studied by x-ray diffraction (XRD) and high resolution electron microscopy (HREM) as part of an investigation of the mechanical behavior of nanocrystalline pure metals. XRD line broadening measur...

G. W. Nieman J. R. Weertman R. W. Siegel

1990-01-01

31

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

32

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

33

Dynamic magnetic behaviour and Mössbauer effect measurements of magnetite nanoparticles prepared by a new technique in the co-precipitation method  

NASA Astrophysics Data System (ADS)

Nanoparticles of magnetite (Fe 3O 4) were prepared by a simple co-precipitation method where a new technique has been employed in this method. Anhydrous ferric chloride (FeCl 3) and ferrous chloride tetrahydrate (FeCl 2 ?4H 2O) were used as precursor materials for the preparation of Fe 3O 4. An X-ray diffraction (XRD) pattern and high resolution transmission electron microscopy (HRTEM) of the as dried sample clearly indicate the formation of the magnetite phase of the sample. ac hysteresis loops in the frequency range of 10-400 Hz and a Mössbauer spectrum of the as prepared sample were observed at room temperature and at ˜20 K. Various magnetic properties viz., coercive field, ac magnetisation, hysteresis loss etc. were also extracted from the observed loops. Results of ac magnetic and room temperature Mössbauer effect measurements indicate the presence of superparamagnetic relaxation of the nanoparticles.

Bandhu, A.; Mukherjee, S.; Acharya, S.; Modak, S.; Brahma, S. K.; Das, D.; Chakrabarti, P. K.

2009-11-01

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

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

36

Magnetic silica spheres with large nanopores for nucleic acid adsorption and cellular uptake.  

PubMed

Template assisted fabrication of magnetic silica nanospheres with large nanopores (MSNLP) and their adsorption and delivery of nucleic acids are reported in this paper. Silica spheres with controlled particle diameter (~400 nm) and large nanopore size (13-24 nm) are prepared by using Brij56 as a template of mesopore, enabling incorporation of magnetic nanocrystals into the particles under mild neutral synthesis conditions. High resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and field-dependent magnetisation measurements confirm that the magnetic nanocrystals have been encapsulated into the silica spheres. The saturation magnetisation values of the resulted magnetic-silica nanocomposites are tunable by adjusting the amount of Fe(3)O(4) magnetic nanocrystals used in the synthesis process. The nitrogen sorption analysis reveals that mesopores with large pore size exist in the silica matrix. After functionalisation of the silica surface with poly-(l-lysine) (PLL), the nanoparticles show strong adsorption capacity (q(m) ranging from 10 to 22.5 ?g/mg) for CpG DNA. We have further demonstrated successful delivery of miRNA into rat proximal tubular epithelial cells, facilitated by efficient cellular uptake of the nanocomposites. This work provides a convenient strategy to prepare MSNLP which can offer a versatile platform for biological applications such as simultaneous drug delivery and magnetic resonance imagining under external magnetic field. PMID:22019119

Liu, Jian; Wang, Bo; Hartono, Sandy Budi; Liu, Tingting; Kantharidis, Phillip; Middelberg, Anton P J; Lu, Gao Qing Max; He, Lizhong; Qiao, Shi Zhang

2012-01-01

37

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

SciTech Connect

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

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

2012-09-01

38

TEM, HRTEM, electron holography and electron tomography studies of gamma' and gamma'' nanoparticles in Inconel 718 superalloy.  

PubMed

The aim of the study was the identification of gamma' and gamma'' strengthening precipitates in a commercial nickel-base superalloy Inconel 718 (Ni-19Fe-18Cr-5Nb-3Mo-1Ti-0.5Al-0.04C, wt %) using TEM dark-field, HRTEM, electron holography and electron tomography imaging. To identify gamma' and gamma'' nanoparticles unambiguously, a systematic analysis of experimental and theoretical diffraction patterns were performed. Using HRTEM method it was possible to analyse small areas of precipitates appearance. Electron holography and electron tomography techniques show new possibilities of visualization of gamma' and gamma'' nanoparticles. The analysis by means of different complementary TEM methods showed that gamma'' particles exhibit a shape of thin plates, while gamma' phase precipitates are almost spherical. PMID:19903242

Dubiel, B; Kruk, A; Stepniowska, E; Cempura, G; Geiger, D; Formanek, P; Hernandez, J; Midgley, P; Czyrska-Filemonowicz, A

2009-11-01

39

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

40

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

41

XRD and Mössbauer spectroscopy study of Ho doped BiFeO3  

NASA Astrophysics Data System (ADS)

The structural and magnetic properties of Ho substituted BiFeO3 (BHFO) have been investigated using 57Fe Mössbauer spectroscopy and X-Ray diffraction (XRD) as a function of temperature. The Mössbauer spectrum obtained at room temperature for the as-synthesized BHFO sample exhibits broadened features due to the hyperfine field distributions related to the local variation of the neighbourhood of Fe and the magnetic hyperfine splitting patterns are indicative of magnetic ordering, mostly probably screwed or slightly antiferromagnetic. The spectrum was fitted with two superimposed asymmetric sextets, with similar hyperfine magnetic fields of Bhf1 = 48.0(1) T and Bhf2 = 49.0(1) T, corresponding to rhombohedral BFO. The hyperfine fields of the magnetic components decreased systematically with increasing temperature to a `field distribution' just below the Néel temperature, TN ~ 600 K. At temperatures above 600 K, the spectral line associated with the Bi25FeO40 impurity phase dominates the spectra. This phase is confirmed by XRD measurements. From the temperature dependence of the site populations of the spectral components an average Debye temperature of ? D = 240(80) K has been estimated.

Ncube, M.; Naidoo, D.; Bharuth-Ram, K.; Billing, D.; Masenda, H.; Sahu, D. R.; Roul, B. K.; Erasmus, R. M.

2013-04-01

42

29Si MAS NMR, XRD and FESEM studies of rice husk silica for the synthesis of zeolites  

Microsoft Academic Search

We have used rice husk ash as a silica source for the synthesis of zeolites. Amorphous silica is a highly reactive silicon source, but not all silica which is amorphous to XRD is equally suitable. The local structure of amorphous silica was investigated by 29Si magic-angle spinning nuclear magnetic resonance (MAS NMR) and field emission scanning electron microscopy (FESEM) in

Halimaton Hamdan; Mohd Nazlan Mohd Muhid; Salasiah Endud; Endang Listiorini; Zainab Ramli

1997-01-01

43

XRD pattern of chitin based polyurethane bio-nanocomposites  

Microsoft Academic Search

Chitin based polyurethane bio-nanocomposites (PUBNC) were prepared by emulsion polymerization. The existence of the intercalated clay by polyurethane (PU) in the hybrid was confirmed using X-ray diffraction (XRD), dynamic mechanical measurements and optical microscope (OM) techniques. The values of enthalpies changes (?H) associated with different bentonite nanoclay contents are much consistent with the crystalline pattern of the synthesized PUBNC samples.

Khalid Mahmood Zia; Mohammad Zuber; Mehdi Barikani; Abdul Jabbar; Muhammad Kaleem Khosa

2010-01-01

44

INFL Guideline on X-Ray Diffraction (XRD).  

National Technical Information Service (NTIS)

X-Ray Diffraction (XRD) is an analytical technique used to identify crystalline compounds. It is a bulk technique, though the volume of material sampled is relatively small (approximately 0.01 cm3 ). Specimens are typically examined in the form of powders...

D. S. Schwartz

2013-01-01

45

Quantitative XRD analysis of zirconia-toughened alumina ceramics  

Microsoft Academic Search

An equation is proposed to give, from XRD data, the tetragonal to monoclinic phase ratio of zirconia in a toughened alumina ceramic material. Using several X-ray wavelengths, with different depths of penetration, quantitative analyses of the tetragonal to monoclinic phase ratio of zirconia as a function of depth were performed, on an as-sintered sample as well as on treated specimens.

R. Fillit; R. P. Homerin; R. J. Schafer; R. H. Bruyas; R. F. Thevenot

1987-01-01

46

XRD analysis and leachability of solidified phenol-cement mixtures  

Microsoft Academic Search

The microstructure and leachability of phenol from solidified phenol-Portland cement mixtures cured up to 6 months were investigated. Phenol was solidified with Type I Portland cement at concentrations of 0.5% and 2% by weight of the cement. XRD studies and pore fluid analyses indicate that phenol inhibits cement setting by reacting with the calcium hydroxide produced during the hydration of

C. Vipulanandan; S. Krishnan

1993-01-01

47

Defects in CVD diamond: Raman and XRD studies  

Microsoft Academic Search

Our earlier studies on diamond films grown by the hot filament CVD (HFCVD) technique have clearly shown the presence of the non-diamond phase in case of samples grown at higher deposition pressures. Results of more detailed investigations of samples grown at higher as well as lower deposition pressures by Raman and XRD techniques are reported in this paper. Appreciable broadening

M Pandey; R D’Cunha; A. K Tyagi

2002-01-01

48

Dealumination of hexagonal (EMT)/cubic (FAU) zeolite intergrowth materials: A SEM and HRTEM study  

SciTech Connect

The aim of this paper is to describe the effects of mild dealumination of the end members (FAU, EMT) and intergrowths produced using crown ethers on the nature of the resultant zeolite. The end members and intergrowths were prepared as described previously and dealuminated according to the following procedure. The intergrowth was prepared from a mixture of crown ethers; 66% 18-crown-6 and 33% 15-crown-5 to give an ordered intergrowth. The zeolites were first calcined to remove the crown ether template (600{degree}C, flowing air, 16 h) and then exchanged with ammonium ions. The zeolite (6 g) was slurried in ammonium acetate solution (450 cm{sup 3}, 0.8 M), and to this was added slowly 15.6 cm{sup 3} of ammonium hexafluorosilicate solution (0.5 M). The mixture was stirred at 75{degree}C for 3 h. The zeolite was collected and carefully washed with water (3 x 100 cm{sup 3}). The dealuminated samples were characterized by {sup 29}Si and {sup 27}Al MAS NMR, X-ray powder diffraction and adsorption measurements. These data indicate that the resultant materials are highly crystalline and showed no signs of structural degradation both in short-range order ({sup 27}Al, {sup 29}Si MAS NMR) and long-range order (XRD). However, the SEM and high-resolution images were particularly informative.

Ohsuna, Tetsu; Watanabe, Denjiro [Iwaki Meisei Univ., Fukushima (Japan); Terasaki, Osamu [Tohoku Univ., Sendai (Japan); Anderson, M.W. [UMIST, Manchester (United Kingdom); Carr, S.W. [Unilever Research, Merseyside (United Kingdom)

1994-12-01

49

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

SciTech Connect

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

Lin, Alex W.H.; Ang, Chung Yen; Patra, Pranab K.; Han Yu; Gu Hongwei [Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, Singapore 138669 (Singapore); Le Breton, Jean-Marie, E-mail: jean-marie.lebreton@univ-rouen.fr [Groupe de Physique des Materiaux, UMR 6634 CNRS, Universite de Rouen, Site Universitaire du Madrillet, Avenue de l'Universite, BP 12 76801 Saint Etienne du Rouvray Cedex (France); Juraszek, Jean; Chiron, Hubert [Groupe de Physique des Materiaux, UMR 6634 CNRS, Universite de Rouen, Site Universitaire du Madrillet, Avenue de l'Universite, BP 12 76801 Saint Etienne du Rouvray Cedex (France); Papaefthymiou, Georgia C. [Department of Physics, Villanova University, Villanova, PA 19085 (United States); Tamil Selvan, Subramanian, E-mail: subramaniant@imre.a-star.edu.sg [Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, Singapore 138669 (Singapore); Ying, Jackie Y., E-mail: jyying@ibn.a-star.edu.sg [Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, Singapore 138669 (Singapore)

2011-08-15

50

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

51

Two-phase nc-TiN/a-(C,CNx) nanocomposite films: A HRTEM and MC simulation study  

NASA Astrophysics Data System (ADS)

The grain growth in two-phase nanocomposite Ti-Cx-Ny thin films grown by reactive close-field unbalanced magnetron sputtering in an Ar-N2 gas mixture with microstructures comprising of nanocrystalline (nc-) Ti(N,C) phase surrounded by amorphous (a-) (C,CNx) 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 ~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 ~5 nm were found to be separated by ~0.5-nm amorphous phases. When C content was further increased (up to ~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.

2013-06-01

52

IMAGE-WARP: a real-space restoration method for high-resolution STEM images using quantitative HRTEM analysis.  

PubMed

We have developed a new method for processing distorted high-resolution scanning transmission electron microscopy (STEM) images. The method is based on finding the displaced vertices in the experimental STEM image and warping to geometrically correct reference grid of the object. As a reference grid for warping a structural model obtained using a high-resolution transmission electron microscopy (HRTEM) analysis of the area of interest is utilised. Combined with quantitative HRTEM analysis the IMAGE-WARP method provides a real-space restoration of high-resolution high-angle annular dark-field (HAADF) STEM images without affecting the original Z-contrast information. The method can be applied to extract valuable compositional atomic-column data from any HAADF-STEM image of any kind of bulk crystals with local occupancy or chemistry fluctuations, stacking faults, special grain boundaries or interfaces, for which we have an available structural model. After the warping, distortion-corrected images can be further enhanced using conventional image-filtering techniques, and finally quantified with HAADF-STEM image simulations. The applicability of the IMAGE-WARP method was illustrated using experimental HAADF-STEM images of a strontium titanate crystal disrupted with a Ruddlesden-Popper-type antiphase boundary. PMID:15885433

Recnik, Aleksander; Möbus, Günter; Sturm, Saso

2005-07-01

53

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

54

FTIR and XRD study of PMMA/PCTFE blend films  

NASA Astrophysics Data System (ADS)

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.; Tripathi, J.; Agrawal, A.; Sharma, A.; Shripathi, T.

2014-04-01

55

Physical characterization of molybdenum oxycarbide catalyst; TEM, XRD and XPS  

Microsoft Academic Search

Controlled reduction of MoO3 can produce different phases of catalytic interest. One of these phases has been considered as being an oxycarbide of molybdenum. Various techniques mainly TEM but also XRD and others have been extensively used to understand the mechanism of formation and the structure of this oxycarbide. Its structure is reminiscent of the MoO3 structure as shown by

Pascale Delporte; Fre´de´ric Meunier; Cuong Pham-Huu; Philippe Vennegues; Marc J. Ledoux; Jean Guille

1995-01-01

56

Photoluminescence Spectra and Magnetic Properties of Hydrothermally Synthesized MnO2 Nanorods  

NASA Astrophysics Data System (ADS)

In this paper, single crystalline tetragonal MnO2 nanorods have been synthesized by a simple hydrothermal method using MnSO4? H2O and Na2S2O8 as precursors. The crystalline phase, morphology, particle sizes and component of the as-prepared nanomaterial were characterized by employing X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and energy-dispersive X-ray spectroscopy (EDS). The photoluminescence (PL) emission spectrum of MnO2 nanorods at room temperature exhibited a strong ultraviolet (UV) emission band at 380 nm, a prominent blue emission peak at 453 nm as well as a weak defect related green emission at 553 nm. Magnetization (M) as a function of applied magnetic field (H) curve showed that MnO2 nanowires exhibited a superparamagnetic behavior at room temperature which shows the promise of synthesized MnO2 nanorods for applications in ferrofluids and the contrast agents for magnetic resonance imaging. The magnetization versus temperature curve of the as-obtained MnO2 nanorods shows that the Néel transition temperature is 94 K.

Toufiq, Arbab Mohammad; Wang, Fengping; Javed, Qurat-Ul-Ain; Li, Quanshui; Li, Yan

2013-11-01

57

Coexistence of plasmonic and magnetic properties in Au89Fe11 nanoalloys  

NASA Astrophysics Data System (ADS)

We describe an environmentally friendly, top-down approach to the synthesis of Au89Fe11 nanoparticles (NPs). The plasmonic response of the gold moiety and the magnetism of the iron moiety coexist in the Au89Fe11 nanoalloy with strong modification compared to single element NPs, revealing a non-linear surface plasmon resonance dependence on the iron fraction and a transition from paramagnetic to a spin-glass state at low temperature. These nanoalloys are accessible to conjugation with thiolated molecules and they are promising contrast agents for magnetic resonance imaging.We describe an environmentally friendly, top-down approach to the synthesis of Au89Fe11 nanoparticles (NPs). The plasmonic response of the gold moiety and the magnetism of the iron moiety coexist in the Au89Fe11 nanoalloy with strong modification compared to single element NPs, revealing a non-linear surface plasmon resonance dependence on the iron fraction and a transition from paramagnetic to a spin-glass state at low temperature. These nanoalloys are accessible to conjugation with thiolated molecules and they are promising contrast agents for magnetic resonance imaging. Electronic supplementary information (ESI) available: TEM images, size histogram, HRTEM images and EFTEM mapping of PEG-AuFeNPs temperature dependence of ?'' calibration curve for analysis of XRD data. See DOI: 10.1039/c3nr01119d

Amendola, Vincenzo; Meneghetti, Moreno; Bakr, Osman M.; Riello, Pietro; Polizzi, Stefano; Anjum, Dalaver H.; Fiameni, Stefania; Arosio, Paolo; Orlando, Tomas; de Julian Fernandez, Cesar; Pineider, Francesco; Sangregorio, Claudio; Lascialfari, Alessandro

2013-05-01

58

Tailoring magnetic and photoluminescence properties in ZnS/ZnO core/shell nanostructures through Cr doping  

NASA Astrophysics Data System (ADS)

Work on doped inverted core/shell semiconductor structure and study of their magnetic and luminescence properties is very rare. We have successfully prepared core/shell (C/S) nanostructure of important semiconductors ZnS core/ZnO shell with doping of chromium in both core and shell regions for tailoring magnetic and luminescence properties. Cooperative exchange of pinned spins at the interface of core and shell magnetic regions lead to ferromagnetism in ZnS:Cr/ZnO:Cr C/S nanoparticles (NP) at room temperature. Ferromagnetic interaction enhances at low temperature. Growth of hexagonal ZnO shell on cubic ZnS NPs in coprepitous aqueous solution has been confirmed by XRD and HRTEM analysis. Substitutional transition metal Cr in ZnS core and/or ZnO shell region could induce magnetic moments, create spin ordering and pinning while on C/S interface and also domain alignment leading to different magnetic states in varied C/S architecture. Cr also induces blue photoluminescence in doped ZnS/ZnO C/S NPs thus paving a possibility of tailoring multifunctional properties in C/S semiconductors architecture.

Chawla, Santa; Sharma, Simmi; Kotnala, R. K.

2013-11-01

59

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

60

CXMS and XRD analyses of heat treated A533B stainless steel  

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

61

4-D XRD for strain in many grains using triangulation  

SciTech Connect

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

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

2006-12-31

62

An NMR, XRD and EDS study of solidification\\/stabilization of chromium with Portland cement and C 3S  

Microsoft Academic Search

Solidification \\/ stabilization (SS) of chromium with Portland cement type I and tricalcium silicate (C3S) was investigated by using the 29Si solid state magic angle spinning\\/nuclear magnetic resonance (29Si MASNMR), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The present study confirms that chromium nitrate can increase the extent of C3S hydration. It also confirms that the chromium ion is

Chiou-Kuo Lin; Jong-Nan Chen; Cheng-Chong Lin

1997-01-01

63

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 Zn 1- xMn xO 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 Zn 2MnO 4/Mn 2O 3 and ZnMnO 3/MnO 2 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 Zn 1- xMn xO 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

64

A combined XRD/XRF instrument for lunar resource assessment  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

65

XRD analysis and leachability of solidified phenol-cement mixtures  

SciTech Connect

The microstructure and leachability of phenol from solidified phenol-Portland cement mixtures cured up to 6 months were investigated. Phenol was solidified with Type I Portland cement at concentrations of 0.5% and 2% by weight of the cement. XRD studies and pore fluid analyses indicate that phenol inhibits cement setting by reacting with the calcium hydroxide produced during the hydration of cement. Phenol leachability was studied using the Toxicity Characteristic Leaching Procedure (TCLP) test recommended by the U. S. EPA. The quantity of phenol leached is dependent on the initial phenol concentration and the curing time and a simple model has been proposed to predict the leachability. Phenol increases the initial and final setting times of cement. The compressive strength of the solidified cement-phenol mixtures decrease with increasing phenol content in the matrix and increase with curing time. The relationship between leaching of phenol and strength of cement-phenol mixtures has been verified.

Vipulanandan, C.; Krishnan, S. (Univ. of Houston, TX (United States). Department of Civil and Environmental Engineering)

1993-07-01

66

Fractionation and characterization of Texas lignite class F fly ash by XRD, TGA, FTIR and SFM  

SciTech Connect

Fly ash is a complicated heterogeneous material and utilization of it requires a detailed knowledge of the physical and chemical characteristics. In the present study Texas lignite class F fly ash was examined by X-ray diffractometer (XRD), thermogravimetric analyzer (TGA), Fourier transformed infrared spectrophotometer (FTIR) and scanning force microscopy (SFM). The XRD and FTIR data indicated that the bulk fly ash was composed of mullite, quartz, cristobalite and amorphous aluminosilicates. The TGA indicated a negligible amount of adsorbed water, and an absence of structural water in the amorphous aluminosilicate phases. The magnetic component of the fly ash was made up of magnetite and present mostly in the coarser fractions [ge]50 [mu]m. The SFM of the bulk fly ash showed the presence of amorphous glassy surface and quartz. The fractionated samples indicated that about 90 wt% of the fly ash was composed of [ge] 50 [mu]m particles. The amorphous component increased with the decreasing particle fractions. Hence, the chemical reactivity of fly ash will increase with the decreasing particle size.

Vempati, R.K. (Gulf Coast Hazardous Substance Research Center, Beaumont, TX (United States)); Rao, A.; Hess, T.R.; Cocke, D.L. (Lamar Univ., Beaumont, TX (United States)); Lauer, H.V. Jr. (Lockheed Science and Engineering Co., Houston, TX (United States))

1994-01-01

67

Combined HRTEM and Auger spectroscopy evidence for the existence of grain boundary premelting in nickel-doped tungsten  

NASA Astrophysics Data System (ADS)

A combined high resolution transmission electron microscopy (HRTEM) and Auger spectroscopy study has revealed the formation of 0.6 nanometer thick, nickel-enriched, "liquid-like" grain boundary (GB) films in Ni-doped W specimens at 95C below the bulk eutectic temperature where the bulk liquid phase is no longer stable [Appl. Phys. Lett. 87, 231902 (2005)]. The stabilization of subeutectic liquid-like grain boundary cores in this model two-component metallic alloy is phenomenologically analogous to the long-sought phenomenon of grain boundary premelting. Despite various macroscopic indications of GB structural transitions, this result, to our knowledge, is the first direct evidence for the existence of such disordered nanostructures at metallic GBs. This observation offers a new explanation to the long-standing mysterious solid-state activated sintering mechanism, where accelerated sintering is attributed to the enhanced diffusion in liquid-like GB layers. This discovery also provides insights to resolve several long-standing controversies, e.g., the mechanisms of Ni-induced abnormal grain growth and GB embrittlement.

Luo, Jian; Gupta, Vivek K.; Yoon, Danghyok; Meyer, Harry M., III

2006-03-01

68

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

SciTech Connect

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

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

1994-02-01

69

Magnetic and morphological properties of CoCu nanowires.  

PubMed

Heterogeneous CoCu nanowires containing different amounts of Co (up to 50% at. wt of Co) are made by electro-deposition (ED) method. CoCu nanowires were grown in AAO templates by varying the current density. The diameter of CoCu nanowires was around 40 nm. Therefore, the growing of CoCu nanowires was compacted with the diameter of AAO templates. The XRD patterns showed that all the CoCu nanowires fabricated via electro-deposition were polycrystalline. At low current density (1.32 mA/cm2), the intensity of Cu (111) peak was very strong. Increasing the current density can be led to increase the intensity of Co (100) peak. High resolution transmission electron microscopy (HRTEM) images of the highest Co content (50%at.) wires showed the existence of layers of polycrystalline heterogeneous CoCu alternating with layers of Cu. The magnetic properties showed that the highest coercivity (7.235 kOe) and squareness (0.754) were found in the unannealed nanowires having the highest Co content. PMID:24734653

Thongmee, S; Tang, I Ming

2014-05-01

70

XRD, TEM and thermal analysis of yttrium doped boehmite nanofibres.  

PubMed

Yttrium doped boehmite nanofibres with varying yttrium content have been prepared at low temperatures using hydrothermal treatment in the presence of the surfactant polyethylene oxide (PEO). The resultant nanofibres were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and thermogravimetric analysis. TEM images showed the resulting nanostructures are predominantly nanofibres when Y doping is less than 5%. When the doping was at the 10 or 20% content Y(OH)3 nanorods were formed. The nanorods show similar morphology to GaO(OH) nanorods. The doped boehmite and the subsequent nanofibres were analyzed by thermogravimetric and differential thermogravimetric methods. The boehmite nanofibres produced thermally transform at higher temperatures than boehmite crystals and boehmite platelets. In general two thermal decomposition steps are observed at around 45 and 379 degrees C assigned to dehydration and dehydroxylation. The dehydration step is attributed to interstitial water trapped between the boehmite layers. The dehydroxylation steps in the boehmite samples with doping above 3% are strongly asymmetric and additional peaks are resolved in the thermal analysis patterns. This peak becomes clear in the 10 and 20% Y doped boehmite samples and is attributed to the thermal decomposition of the Y(OH)3 nanorods. PMID:19452988

Zhao, Yanyan; Frost, Ray L

2009-05-01

71

Design of Smart PEO-PPO-PEO-Magnetic Drug Delivery System for Alzheimer's Diseases Diagnosis and Therapy.  

PubMed

Amyloid-? (A?) oligomers are more likely to be the pathogenic agents of Alzheimer's disease. Development of multiple approaches in detection and clearance pathway for A?, may eventually lead to diagnosis and treatments of AD. Following this concept, we proposed temperature-responsive magnetic drug delivery system (DDS). This system designed to enhance imaging tool and controlled drug delivery with the aid of conjugated antibodies to amyloid-derived diffusible ligands (anti-ADDLs), which can identify targeted ADDLs. The magnetic cores compose of conjugated Congo red (CR) to maghemite (Fe2O3) (CR-Fe2O3) have shown great advantage as multimodal imaging agents, while superparamagnetic Fe2O3 also possesses the hyperthermia therapy function. Pluronic F127 poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) PEO-PPO-PEO block copolymer known to be stimuli-responsive and show structure changes when subjected to external, temperature and magnetic signals. To form nanocomposites, magnetic cores coated with Pluronic and produce core/shell structure. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and high-resolution transmission electron microscope (HR-TEM) were used to characterize as-synthesized magnetic nanocomposites (MNCs). Furthermore, Vibrating magnetometer experiments showed that MNCs have higher magnetization value than bare magnetic nanoparticles (MNPs) and are easy to conduct with an external magnetic field. The dependence of hydrodynamic size of MNCs to the temperature showed an increase in temperature corresponds to a decrease in the size. These results confirm that proposed system can be engineered and employed as smart drug delivery system for AD treatment. PMID:22934765

Dehvari, Khalilalrahman; Lin, Kuen-Song

2012-08-16

72

Graphitization in a high-pressure, low-temperature metamorphic gradient: a Raman microspectroscopy and HRTEM study  

NASA Astrophysics Data System (ADS)

The graphitization of carbonaceous material (CM) in a high-pressure metamorphic gradient is characterized along a cross section in the Schistes Lustrés formation, Western Alps. Along this 25-km cross section, both the CM precursor and the host-rock lithology are homogeneous, and the prograde evolution of the pressure-temperature metamorphic conditions from the lower blueschist-facies (13 kbar, 330 °C) to the eclogite-facies (20 kbar, 500 °C) is tightly constrained by literature data. Raman microspectroscopy shows that at the micrometre scale, this process is progressive and continuous with increasing metamorphic grade, and that the structure of CM is very sensitive to temperature variations. At the nanometre scale (HRTEM), the CM is composed of a mixture of a microporous phase and an onion-ring like phase, both known as non-graphitizing under the effect of temperature at ambient pressure. The HP-LT graphitization produces structurally and microtexturally heterogeneous CM. With increasing metamorphic grade, the graphitization of the two types of CM proceeds up to the triperiodic graphite stage because of microtextural and structural changes that are specific to each type of CM. The microporous material is progressively transformed into graphite through a macroporous transitional stage. In this case, graphitization mainly occurs on the pore walls as a result of pore growth. In the case of concentric onion-ring like material, graphitization occurs in the regions with the largest radius of curvature, i.e. on the outer part of the ring. In comparison with 1-bar experiments, pressure seems to induce microtextural changes, which allows the subsequent structural modifications of the starting material.

Beyssac, Olivier; Rouzaud, Jean-Noël; Goffé, Bruno; Brunet, Fabrice; Chopin, Christian

2002-02-01

73

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 TiSi 2, ?-FeSi 2 and NiSi 2 were generated as the model predicts, while a mixture of CrSi + CrSi 2 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 2p 3/2 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 2p 3/2 peak of NiSi 2 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 2p 3/2 level was shown for ?-FeSi 2 and negative binding energy shifts of 0.1 and 0.3 eV were determined for CrSi + CrSi 2 and TiSi 2, respectively.

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

2012-02-01

74

One-pot synthesis of highly monodispersed ferrite nanocrystals: surface characterization and magnetic properties.  

PubMed

In the present study, a facile one-pot synthetic route, utilizing a strong polar organic solvent, N-methyl 2-pyrrolidone (NMP), is demonstrated to obtain highly monodispersed ferrite nanocrystals. The equimolar mixture of oleic acid, C(17)H(33)COOH (R-COOH), and oleylamine, C(18)H(35)NH(2) (R'-NH(2)), was used to coat the magnetic nanocrystals. Structural and magnetic properties of the ferrite nanocrystals were studied by a multitechnique approach including X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry (VSM), and Mössbauer spectroscopy. FTIR spectral analysis indicates oleylamine helps in deprotonation of oleic acid, resulting in the formation of an acid-base complex, R-COO¯:NH(3)(+)-R', which acts as binary capping agent. Structural and coordination differences of iron were studied by XPS and Mössbauer spectral analysis. XPS analysis was carried out to examine the oxidation state of iron ions in iron oxide nanocrystals. The presence of a magnetically dead layer (?0.38 and ?0.67 nm) and a nonmagnetic organic coating (?2.3 and ?1.7 nm) may substantially reduce the saturation magnetization values for CoFe(2)O(4) and Fe(3)O(4) nanocrystals, respectively. The energy barrier distribution function of magnetic anisotropy was derived from the temperature dependent decay of magnetization. A very narrow energy barrier distribution elucidates that the ferrite nanocrystals obtained in this study are highly monodispersed. PMID:21894994

Verma, Seema; Pravarthana, D

2011-11-01

75

FAST TRACK COMMUNICATION: Applications of the rotating orientation XRD method to oriented materials  

NASA Astrophysics Data System (ADS)

The rotating orientation x-ray diffraction (RO-XRD) method, based on conventional XRD instruments by a modification of the sample stage, was introduced to investigate the orientation-related issues of such materials. In this paper, we show its applications including the determination of single crystal orientation, assistance in crystal cutting and evaluation of crystal quality. The interpretation of scanning patterns by RO-XRD on polycrystals with large grains, bulk material with several grains and oriented thin film is also presented. These results will hopefully expand the applications of the RO-XRD method and also benefit the conventional XRD techniques.

Guo, Zhenqi; Jin, Li; Li, Fei; Bai, Yu

2009-01-01

76

An EFTEM\\/HRTEM high-resolution study of the near surface of labradorite feldspar altered at acid pH: evidence for interfacial dissolution-reprecipitation  

Microsoft Academic Search

Using an approach combining high-resolution and energy-filtered transmission electron microscopy (HRTEM and EFTEM), we have studied with Å to nm-spatial resolution the interfacial region that delimits the near-surface altered zone and non-altered labradorite feldspar after dissolution under acid pH conditions. The interface is characterized by extremely sharp and spatially coincident changes in structure and chemistry. The 500-nm-thick altered zone is

R. Hellmann; J.-M. Penisson; R. L. Hervig; J.-H. Thomassin; M.-F. Abrioux

2003-01-01

77

Crystal structure of La{sub 0.4}Sr{sub 0.6}CoO{sub 2.71} investigated by TEM and XRD  

SciTech Connect

The structure of the oxygen-deficient perovskite La{sub 0.4}Sr{sub 0.6}CoO{sub 3-{delta}} ({delta}=0.29) was investigated by transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). Domains between 50 and 250 nm in size were observed in the electron microscope. Weak superstructure reflections were found with both X-ray and electron diffraction. Investigations of these superstructure reflections by selected area electron diffraction (SAED) and convergent beam electron diffraction (CBED) showed that the domains in a crystal are orientated in a 90 deg. relationship. High-resolution transmission electron microscopy (HRTEM) images from the domain boundary also revealed a 90 deg. orientation dependency. Using the symmetry of CBED patterns, the point group 4/mmm was determined. By comparing reflections from the SAED pattern with possible reflections, the space group I4/mmm (No. 139) could be isolated and finally the crystal structure was refined by Rietveld refinement. - Graphical abstract: Two adjacent domains show different orientation of the c-axis of the tetragonal unit cell in the according convergent beam electron diffraction patterns.

Gspan, C. [Institute for Electron Microscopy and Fine Structure Research, Graz University of Technology, Steyrergasse 17, A-8010 Graz (Austria); Centre for Electron Microscopy Graz, Steyrergasse 17, A-8010 Graz (Austria)], E-mail: christian.gspan@felmi-zfe.at; Grogger, W. [Institute for Electron Microscopy and Fine Structure Research, Graz University of Technology, Steyrergasse 17, A-8010 Graz (Austria); Centre for Electron Microscopy Graz, Steyrergasse 17, A-8010 Graz (Austria); Bitschnau, B. [Institute of Physical and Theoretical Chemistry, Graz University of Technology, Technikerstrasse 4, A-8010 Graz (Austria); Bucher, E.; Sitte, W. [Department of General, Analytical and Physical Chemistry, University of Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria); Hofer, F. [Institute for Electron Microscopy and Fine Structure Research, Graz University of Technology, Steyrergasse 17, A-8010 Graz (Austria); Centre for Electron Microscopy Graz, Steyrergasse 17, A-8010 Graz (Austria)

2008-11-15

78

Comparative Raman and HRTEM study of nanostructured GaN nucleation layers and device layers on sapphire (0001).  

PubMed

Raman spectroscopy in conjunction with high-resolution transmission electron microscopy (HRTEM) has been used to study structural characteristics and strain distribution of the nanostructured GaN nucleation layer (NL) and the GaN device layer on (0001) sapphire substrates used for light-emitting diodes and lasers. Raman peaks corresponding to the cubic and the hexagonal phase of GaN are observed in the Raman spectrum from 15 nm and 45 nm NLs. A comparison of the peak intensities for the cubic and hexagonal phases of GaN in the NLs suggests that the cubic phase is dominant in the 15 nm NL and the hexagonal phase in the 45 nm NL. An increase in the density of stacking faults in the metastable cubic GaN (c-GaN) phase with increasing growth time lowers the system energy as well as locally converts c-GaN phase into hexagonal GaN (h-GaN). It also explains the observation of the more intense peaks of h-GaN in the 45 nm NL compared to c-GaN peaks. For the sample wherein an h-GaN device layer was grown at higher temperatures on the NL, narrow Raman peaks corresponding to only h-GaN were observed, confirming the high-quality of the films. The peak shift of the E2(H)(LO) mode of h-GaN in the NLs and the h-GaN film suggests the presence of a tensile stress in the NL which is attributed to defects such as stacking faults and twins, and a compressive stress in high-temperature grown h-GaN film which is attributed to the thermal-expansion mismatch between the film and the substrate. The peak shifts of the substrate also reveal that during the low temperature growth of the NL the substrate is under a compressive stress which is attributed to defects in the NL and during the high temperature growth of the device layer, there is a tensile strain in the substrate as expected from differences in coefficients of thermal expansion of the film and the substrate during the cooling cycle. PMID:19198336

Pant, P; Narayan, J; Wushuer, A; Manghnani, M H

2008-11-01

79

Sub-solidus phase relations in CeO 2–YSZ and ThO 2–YSZ systems: XRD, high temperature-XRD and EPMA studies  

Microsoft Academic Search

In the present manuscript, synthesis, XRD, high temperature-XRD as well as electron probe for microanalysis (EPMA) studies on CeO2–YSZ and ThO2–YSZ are being reported. It is found that CeO2–YSZ system shows formation of a cubic solid solution throughout the homogeneity range. The lattice parameter of this cubic solid solution in CeO2–YSZ system decreases linearly on going from CeO2 to YSZ

V. Grover; P. Sengupta; A. K. Tyagi

2007-01-01

80

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

PubMed Central

Nanolithography techniques in a scanning electron microscope/focused ion beam are very attractive tools for a number of synthetic processes, including the fabrication of ferromagnetic nano-objects, with potential applications in magnetic storage or magnetic sensing. One of the most versatile techniques is the focused electron beam induced deposition, an efficient method for the production of magnetic structures highly resolved at the nanometric scale. In this work, this method has been applied to the controlled growth of magnetic nanostructures using Co2(CO)8. The chemical and structural properties of these deposits have been studied by electron energy loss spectroscopy and high-resolution transmission 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.

2011-01-01

81

Physical properties of magnetic macromolecule-metal and macromolecule-metal oxide nanoparticle complexes  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles are of considerable interest owing to their potential applications in biotechnology and the magnetic recording industry. Iron oxides have received much attention owing to their oxidative stability and biocompatibility; however, other transition metals and their alloys are also under investigation. Cobalt has one of the largest magnetic susceptibilities of these materials, but it readily oxidizes upon exposure to air resulting in antiferromagnetic oxide. Hence, coating cobalt nanoparticles with an oxygen-impermeable sheath would confer numerous benefits. Cobalt nanoparticles were prepared by the thermolysis of dicobalt octacarbonyl in two block copolymer micellar systems, wherein the copolymers were precursors to graphite or silica. Subsequent heat treatment of the samples at 600--700°C was conducted to condense the polymer coating around the cobalt nanoparticles and form oxygen impervious graphite or silica sheaths. Magnetic and structural characterization of these novel materials afforded pertinent information about their physical properties. Magnetic susceptometry indicated that the graphite coated cobalt nanoparticles resisted oxidation far over one year. The silica coated cobalt nanoparticles had high saturated specific magnetic moments, but the coatings were brittle and grinding the particles resulted in oxidation over time. Transmission electron microscopy (TEM), high-resolution TEM (HRTEM) and energy-filtered TEM (EFTEM) were employed to study particle size and structural differences of the cobalt nanoparticles before and after heat treatment. The mean particle size and size distribution increased for the graphite coated cobalt particles, due to particle sintering at 700°C. In the silica coated cobalt nanoparticle system, the mean particle size increased when the sample was heat-treated at 600°C leading to a bimodal distribution. This bimodal distribution was explained by a fraction of the particles sintering, while others remained discrete. When the silica system was heat treated at 700°C, the particle size and size distribution remained similar to those of the pre-heat-treated sample, indicating that no sintering had taken place. The rapid pyrolysis of the polymer at 700°C may serve to lock the cobalt nanoparticles into a silica matrix, thus preventing them from coming into contact with one another and sintering. Several diffraction techniques (selected area electron diffraction (SAD), nano-beam electron diffraction (NBD) and x-ray diffraction (XRD)) were used to probe the crystal structure of graphite and silica coated cobalt nanoparticies, which was determined to be predominantly face-centered cubic. Anisotropic magnetic nanoparticles (nanorods) have an increased magnetophoretic mobility over spherical magnetic nanoparticles with the same equatorial radius. This property makes them attractive candidates for in vivo biological applications. Anisotropic mixed ferrite nanoparticles were coated with a biocompatible hydrophilic block copolymer to render them dispersible in aqueous media. Polymer coated mixed ferrite particles exhibited magnetic properties similar to that of pure magnetite, as the total level of other transition metals in the nanoparticulate system was less than 5%. Electron energy loss spectroscopy (EELS) and (EFTEM) confirmed that the dominant elements in the mixed ferrite nanoparticles were iron and oxygen. Furthermore, HRTEM, SAD and XRD analyses indicated that the crystal structure for the mixed ferrite nanoparticles was inverse spinel. X-ray diffraction peaks at low angles for the coated mixed ferrite rods corresponded to poly(ethylene oxide) peaks, suggesting that the block copolymer employed as a dispersant was associated with the particles.

Zalich, Michael Andrew

82

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.

2010-10-27

83

Novel Sample-handling Approach for XRD Analysis with Minimal Sample Preparation  

NASA Technical Reports Server (NTRS)

Sample preparation and sample handling are among the most critical operations associated with X-ray diffraction (XRD) analysis. These operations require attention in a laboratory environment, but they become a major constraint in the deployment of XRD instruments for robotic planetary exploration. We are developing a novel sample handling system that dramatically relaxes the constraints on sample preparation by allowing characterization of coarse-grained material that would normally be impossible to analyze with conventional powder-XRD techniques.

Sarrazin, P.; Chipera, S.; Bish, D.; Blake, D.; Feldman, S.; Vaniman, D.; Bryson, C.

2004-01-01

84

Synthesis of manganese oxide nanocrystal by ultrasonic bath: effect of external magnetic field.  

PubMed

A novel technique was used for the synthesis of manganese oxide nanocrystal by applying an external magnetic field (EMF) on the precursor solution before sonication with ultrasonic bath. The results were compared in the presence and absence of EMF. Manganese acetate solution as precursor was circulated by a pump at constant speed (7 rpm, equal to flow rate of 51.5 mL/min) in an EMF with intensity of 0.38 T in two exposure times (t(MF), 2h and 24h). Then, the magnetized solution was irradiated indirectly by ultrasonic bath in basic and neutral media. One experiment was designed for the effect of oxygen atmosphere in the case of magnetic treated solution in neutral medium. The as prepared samples were characterized with X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (HRTEM, TEM), energy-dispersive spectrum (EDS), and superconducting quantum interference device (SQUID) analysis. In neutral medium, the sonication of magnetized solution (t(MF), 24h) led mainly to a mixture of Mn(3)O(4) (hausmannite) and ?-MnOOH (manganite) and sonication of unmagnetized solution led to a pure Mn(3)O(4). In point of particle size, the larger and smaller size of nanoparticles was obtained with and without magnetic treatment, respectively. In addition, the EMF was retarded the nucleation process, accelerated the growth of the crystal, and increased the amount of rod-like structure especially in oxygen atmosphere. In basic medium, a difference was observed on the composition of the products between magnetic treated and untreated solution. For these samples, the magnetic measurements as a function of temperature were exhibited a reduction in ferrimagnetic temperature to T(c)=39K, and 40K with and without magnetic treatment, respectively. The ferrimagnetic temperature was reported for the bulk at T(c)=43K. A superparamagnetic behavior was observed at room temperature without any saturation magnetization and hysteresis in the measured field strength. The effect of EMF on the sample prepared in the basic medium was negligible but, in the case of neutral medium, the EMF affected the slope of the magnetization curves. The magnetization at room temperature was higher for the samples obtained in neutral medium without magnetic treatment. In addition, a horizontal shift loop was observed in neutral medium at low temperature. PMID:22221536

Bastami, Tahereh Rohani; Entezari, Mohammad H

2012-07-01

85

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

86

An EFTEM\\/HRTEM high-resolution study of the near surface of labradorite feldspar altered at acid pH: evidence for interfacial dissolution-reprecipitation  

Microsoft Academic Search

Using an approach combining high-resolution and energy-filtered transmission electron microscopy (HRTEM and EFTEM), we have\\u000a studied with Å to nm-spatial resolution the interfacial region that delimits the near-surface altered zone and non-altered\\u000a labradorite feldspar after dissolution under acid pH conditions. The interface is characterized by extremely sharp and spatially\\u000a coincident changes in structure and chemistry. The 500-nm-thick altered zone is

R. Hellmann; J.-M. Penisson; R. L. Hervig; J.-H. Thomassin; M.-F. Abrioux

2003-01-01

87

Fractionation and characterization of Texas lignite class F fly ash by XRD, TGA, FTIR and SFM  

Microsoft Academic Search

Fly ash is a complicated heterogeneous material and utilization of it requires a detailed knowledge of the physical and chemical characteristics. In the present study Texas lignite class F fly ash was examined by X-ray diffractometer (XRD), thermogravimetric analyzer (TGA), Fourier transformed infrared spectrophotometer (FTIR) and scanning force microscopy (SFM). The XRD and FTIR data indicated that the bulk fly

R. K. Vempati; A. Rao; T. R. Hess; D. L. Cocke; H. V. Jr. Lauer

1994-01-01

88

TEM, XRD and Raman scattering of germanium processed by severe deformation  

Microsoft Academic Search

Nanocrystalline (NC) Ge samples processed by severe plastic deformation under high pressure (6 GPa) were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman scattering. TEM studies of NC Ge revealed a mean grain size of about 24 nm and high angle misorientations of neighbouring grains. The XRD patterns showed decreasing peak intensities, peak broadening and a mean

R. K. Islamgaliev; R. Kuzel; E. D. Obraztsova; J. Burianek; F. Chmelik; R. Z. Valiev

1998-01-01

89

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

90

Raman and XRD Study of Icelandic Tephra: Characterisation of Alteration Minerals and Implications for Mars  

NASA Astrophysics Data System (ADS)

Icelandic tephra has been analysed using Raman and XRD to identify the minerals present. This data will improve understanding of the post-magmatic history of Iceland and develop methodologies for the analysis of remotely collected Raman data.

Bathgate, E.; Maynard-Casely, H.; Caprarelli, G.; Xiao, L.; Stuart, B.; Smith, K.

2014-06-01

91

A versatile and inexpensive XRD sample holder for highly radioactive or hazardous samples.  

SciTech Connect

Two XRD sample holders have been designed for use with highly radioactive samples. An injection mold that allows us to produce the holders inexpensively has been constructed for one of the holders. These holders are suitable for single-time use. The ease of use and the disposable nature have resulted in a dramatic reduction in personnel exposure and an uncontaminated XRD unit. A second holder, based on the design of the first, is used to obtain XRD patterns from powders where preferred orientation is an issue and from clays. Both holders result in negligible background, since the sample is essentially levitated in the x-ray beam. This is a benefit over other methods, such as collodion, that introduce significant background to the XRD pattern.

Strachan, Denis M.(BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB); Schaef, Herbert T.(BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB); Schweiger, Michael J.(BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB); Simmons, Kevin L.(BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB); Woodcock, Leslie J.(BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB); Krouse, Michael K.(BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB)

2003-03-15

92

Calculation of XRD patterns of simulated FDU-15, CMK-5, and CMK-3 carbon structures  

Microsoft Academic Search

XRD patterns of model structures of the ordered mesoporous carbon materials FDU-15, CMK-5, and CMK-3 have been calculated. The structure models had been derived by filling tubular (CMK-5), rod-like (CMK-3), or channel wall (FDU-15) spaces in a given unit cell with carbon atoms. The generated carbon sites then have been used for the calculation of the XRD patterns. It could

Wolfgang Schmidt

2009-01-01

93

Thermo-XRD-analysis of montmorillonite treated with protonated Congo-red. Curve fitting  

Microsoft Academic Search

The adsorption of protonated Congo red (CR) by montmorillonite was investigated by thermo-XRD-analysis. Montmorillonite was loaded at pH 1 with increasing amounts of CR up to 75 mmol per 100 g clay. Diffractograms of samples treated at 420 °C showed broad peaks and were curve-fitted to determine the different basal spacings, which composed the XRD peaks. The broad peak of

Z. Yermiyahu; I. Lapides; S. Yariv

2005-01-01

94

Characterization of collision cascade damage in Ca{sub 2}La{sub 8}(SiO{sub 4}){sub 6}O{sub 2} by HRTEM  

SciTech Connect

Ca{sub 2}La{sub 8}(SiO{sub 4}){sub 6}O{sub 2} thin crystals become amorphous under ion beam irradiation. The ion dose required for complete amorphization of the thin crystal (critical amorphization dose, D{sub c}) increased with the increasing irradiation temperature and decreased with ion mass at elevated temperatures. Samples irradiated with 1-1.5 MeV Ar{sup +}, Kr{sup +} and Xe{sup +} ions to doses much lower than Dc, in the temperature range from 20 to 498 K were used for a detailed HRTEM study to better understand the amorphization process. The residual collision cascade damage after irradiation appeared as manometer scale amorphous domains. The images of these domains are extremely sensitive to the sample thickness. Small domains of cascade size were only found at the very thin edge of the sample. In thicker regions, amorphous domains appear after higher doses as the result of cascade overlap in projection. At higher temperatures, the observed amorphous domains are smaller indicating thermal recovery at the amorphous/crystalline interface. The amorphous domains are also larger in size after irradiation with ions of higher mass at a fixed ion dose. These results are consistent with the Dc-temperature curves determined by in situ TEM with the HVEM-Tandem Facility at Argonne National Laboratory. The width of the amorphous rim along the edge of the specimen grew with increasing ion dose suggesting that amorphization also proceeds from the sample surface. Images of the collision cascade damage were compared to the cascade sizes calculated with the TRIM code. Some digitally acquired HRTEM images of the cascade damage were processed to reveal more detailed information.

Weber, W.J.; Wang, L.M.

1994-12-01

95

Magnetization enhancement of magnetic nanoparticles coated with polypyrrole  

NASA Astrophysics Data System (ADS)

We are presenting the synthesis and characterization of hybrid structures obtained by coating "soft" magnetic nanoparticles like perovskite manganites of La0.67Sr0.33MnO3 (LSMO) type with polypyrrole (PPy). The thin amorphous layer of PPy was observed by HRTEM and analyzed by XPS and XANES techniques. The existence of superparamagnetism is evidenced by the very small values of coercive fields and FC and ZFC behaviors. The surface modification of the magnetic nanoparticles generates an increase of the saturation magnetization. This novel effect is attributed to a charge transfer process between the conducting polymer and the surface layers of the magnetic cores. As a result, a significant increase of the surface contribution to the overall magnetic moment of the nanoparticles is produced. The effect is correlated with the temperature dependences of coercive field and of the ESR integral intensities.

Pana, O.; Leostean, C.; Soran, M. L.; Stefan, M.; Macavei, S.; Gheorghe, N. G.; Teodorescu, C. M.

2012-02-01

96

Crystal structure, physical properties and HRTEM investigation of the new oxonitridosilicate EuSi2O2N2.  

PubMed

The new layered oxonitridosilicate EuSi(2)O(2)N(2) has been synthesized in a radio-frequency furnace at temperatures of about 1400 degrees C starting from europium(III) oxide (Eu(2)O(3)) and silicon diimide (Si(NH)(2)). The structure of the yellow material has been determined by single-crystal X-ray diffraction analysis (space group P1 (no. 1), a=709.5(1), b=724.6(1), c=725.6(1) pm, alpha=88.69(2), beta=84.77(2), gamma=75.84(2) degrees ,V=360.19(9)x10(6) pm(3), Z=4, R1=0.0631, 4551 independent reflections, 175 parameters). Its anionic Si(2)O(2)N(2) (2-) layers consist of corner-sharing SiON(3) tetrahedra with threefold connecting nitrogen and terminal oxygen atoms. High-resolution transmission electron micrographs indicate both ordered and disordered crystallites as well as twinning. Magnetic susceptibility measurements of EuSi(2)O(2)N(2) exhibit Curie-Weiss behavior above 20 K with an effective magnetic moment of 7.80(5) mu(B) Eu(-1), indicating divalent europium. Antiferromagnetic ordering is detected at 4.5(2) K. EuSi(2)O(2)N(2) shows a field-induced transition with a critical field of 0.50(5) T. The four crystallographically different europium sites cannot be distinguished by (151)Eu Mössbauer spectroscopy. The room-temperature spectrum is fitted by one signal at an isomer shift of delta=-12.3(1) mm s(-1) subject to quadrupole splitting of DeltaE(Q)=-2.3(1) mm s(-1) and an asymmetry parameter of 0.46(3). Luminescence measurements show a narrow emission band with regard to the four crystallographic europium sites with an emission maximum at lambda=575 nm. PMID:16819723

Stadler, Florian; Oeckler, Oliver; Höppe, Henning A; Möller, Manfred H; Pöttgen, Rainer; Mosel, Bernd D; Schmidt, Peter; Duppel, Viola; Simon, Arndt; Schnick, Wolfgang

2006-09-01

97

The mineralogy and chemistry analyser (MARS-XRD) for the ExoMars 2018 mission  

NASA Astrophysics Data System (ADS)

The Mineralogy and Chemistry Analyser (MARSXRD) is a miniaturised X-ray diffraction and fluorescence (XRD/XRF) spectrometer aimed to the mineralogical characterisation of Martian rocks. Simultaneously, MARS-XRD is able to acquire the diffraction pattern for mineralogical phases identification and the X-ray fluorescence spectrum for the chemical species, providing a complete rock characterization. The X-ray diffractometer (XRD) is the routine instrument used in every Earth Science laboratory to provide the mineralogical composition of rocks. XRD produces unequivocal results because it is based on the recognition of the geometrical properties of the crystal lattice. This kind of investigation is an extremely useful tool to define the textural and petro-mineralogical characteristics of the Martian rocks or soils and provide information on the past Martian environment conditions related to life. The analytic range we plan to cover includes all the silicate minerals, from clays or other phyllosilicates characterised by high interplanar lattice distance, to oxide and carbonates or evaporates (mainly sulphates). This rock spectrum is what we expect to be the target for exobiological exploration. These data will be integrated with those obtained by elemental analysis, in order to determine the exact elemental chemistry characterization of rock components. As mineralogy can be unambiguously derived from XRD analysis, it is probably our most powerful tool for distinguishing targets of biologic importance. In summary, the main scientific objectives of the proposed XRD/XRF instrument, Mars-XRD, are: - In situ determination of the mineral paragenesis of rock samples; - The characterization of the origin of rock samples; - Determination of alteration processes; - Understanding the exobiological potential of the samples. The hardware is developed by the Thales Alenia Space Italia with an important contribution of the Univ. of Leicester for the detection system.

Marinangeli, L.; Hutchinson, I. B.; Stevoli, A.; Adami, G.; Ambrosi, R.; Amils, R.; Assis Fernandes, V.; Baliva, A.; Basilevsky, A. T.; Benedix, G.; Bland, P.; Böttger, A. J.; Bridges, J.; Caprarelli, G.; Cressey, G.; Critani, F.; D'Alessandro, N.; Delhez, R.; Domeneghetti, C.; Fernandez-Remolar, D.; Filippone, R.; Fioretti, A. M.; Garcia Ruiz, J. M.; Gilmore, M.; Hansford, G. M.; Iezzi, G.; Ingley, R.; Ivanov, M.; Marseguerra, G.; Moroz, L.; Pelliciari, C.; Petrinca, P.; Piluso, E.; Pompilio, L.; Sykes, J.; Westall, F.

2011-10-01

98

Definitive Mineralogical Analysis of Mars Analog Rocks Using the CheMin XRD/XRF Instrument  

NASA Technical Reports Server (NTRS)

Mineral identification is a critical component of Mars Astrobiological missions. Chemical or elemental data alone are not definitive because a single elemental or chemical composition or even a single bonding type can represent a range of substances or mineral assemblages. Minerals are defined as unique structural and compositional phases that occur naturally. There are about 15,000 minerals that have been described on Earth, all uniquely identifiable via diffraction methods. There are likely many minerals yet undiscovered on Earth, and likewise on Mars. If an unknown phase is identified on Mars, it can be fully characterized by structural (X-ray Diffraction, XRD) and elemental analysis (X-ray Fluorescence, XRF) without recourse to other data because XRD relies on the principles of atomic arrangement for its determinations. XRD is the principal means of identification and characterization of minerals on Earth.

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

2004-01-01

99

Evaluation of effective elastic constants for polycrystalline PZT thin films by XRD patterns and pole figures  

Microsoft Academic Search

Polycrystalline PbZr0.52Ti0.48O3 (PZT) thin films with different thicknesses were prepared by metal-organic decomposition (MOD) at different thermal decomposition\\u000a temperatures, and their effective elastic constants were evaluated with X-ray diffraction (XRD) techniques. The relative intensities\\u000a of textures in the thin films were analyzed from XRD patterns, and the effective elastic constants were calculated by averaging\\u000a over orientations according to the relative

Xue-jun Zheng; Li-ping Tang; Qin-yong Wu; Bo Wu

2007-01-01

100

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

101

High temperature XRD of Cu2.1Zn0.9SnSe4  

NASA Astrophysics Data System (ADS)

Quaternary compound with chemical composition Cu2.1Zn0.9SnSe4 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; Mallik, Ramesh Chandra

2014-04-01

102

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

NASA Astrophysics Data System (ADS)

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.

2010-06-01

103

Synthesis and characterization of 3D Cu0.45Mn0.55O2 nanoflowers with novel photoluminescence and magnetic properties  

NASA Astrophysics Data System (ADS)

In this paper, three-dimensional (3D) Cu0.45Mn0.55O2 nanoflowers self-assembled by interconnecting dense stacked single-crystalline nanoplates have been prepared using the template-free hydrothermal growth method. The morphology, phase structure and composition of the as-prepared nanomaterial were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) with selected area electron diffraction (SAED) and energy-dispersive X-ray spectroscopy (EDX). FESEM and TEM analyses show that the size of 3D Cu0.45Mn0.55O2 nanoflowers is in the range of 1-1.5 ?m and the thickness of interconnected nanoplates is about 40 nm on the average. The photoluminescence (PL) spectra of the as-prepared Cu0.45Mn0.55O2 nanostructures at room temperature exhibits prominent emission bands located in red-violet spectral region. Moreover, magnetic investigations revealed the weak ferromagnetic behavior of the as-prepared Cu0.45Mn0.55O2 nanoflowers and reported for the first time using vibrating sample magnetometer (VSM).

Toufiq, Arbab Mohammad; Wang, Fengping; Javed, Qurat-Ul-Ain; Li, Quanshui; Li, Yan

2014-04-01

104

Improved magnetic and ferroelectric properties of Sc and Ti codoped multiferroic nano BiFeO3 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 BiFe0.925Sc0.05Ti0.025O3 nanoparticles. A marked reduction in the leakage current was seen compared to undoped BiFeO3. Magnetoelectric coupling was also observed in the BiFe0.925Sc0.05Ti0.025O3 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

105

A new FESEM procedure for assessment of XRD microstructural data of kaolinites  

Microsoft Academic Search

A sample preparation method for FESEM microstructural analysis of sheet silicates using oriented aggregates on metallic strips parallel to the electronic beam is described. The method allows the easy measurement of thickness of kaolinite crystallites. The results have been compared to the apparent crystallite size measured by XRD The performed measurements for a set of selected kaolinites are in the

J. V. Clausell; J. Bastida; F. J. Serrano; P. Pardo; F. J. Huertas

2007-01-01

106

Estimate of clay minerals amounts from XRD pattern modeling: The Arquant model  

Microsoft Academic Search

This work presents an XRD pattern model applied to the quantification of clay minerals in the <2?m fraction. The model is based on a linear combination of patterns previously simulated with specific codes. The modeling procedure is especially adapted to the oriented deposits performed from a suspension although it can also apply to the oriented pastes. The estimate of mica-like

Philippe Blanc; Olivier Legendre; Eric C. Gaucher

2007-01-01

107

Studying cellulose fiber structure by SEM, XRD, NMR and acid hydrolysis  

Microsoft Academic Search

Cotton linters were partially hydrolyzed in dilute acid and the morphology of remaining macrofibrils was studied with scanning electron microscopy (SEM) under various magnifications. The crystalline region in cellulose is composed of microfibril bundles instead of separated microfibrils. These microfibril bundles in the macrofibrils were exposed by removing amorphous cellulose on and near the surface of the macrofibers. XRD suggests

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

2007-01-01

108

XRD evaluation of KOH activation process and influence of coal rank  

Microsoft Academic Search

Three Japanese coals with different rank (Ohmine, Miike and Taiheiyo coals) were activated with KOH from 300 to 850°C. Higher rank coal with lower oxygen content showed a high yield and also a large specific surface area determined by N2 adsorption isotherms. X-ray diffraction (XRD) patterns of the activated carbons were measured to characterize stacking structure of aromatic layers by

N Yoshizawa; K Maruyama; Y Yamada; E Ishikawa; M Kobayashi; Y Toda; M Shiraishi

2002-01-01

109

XRD study of the goethite-hematite transformation: Application to the identification of heated prehistoric pigments  

Microsoft Academic Search

When heated, yellow goethite dehydrates and transforms to red hematite. Both iron oxides were used by the Palaeolithic artists as pigments, one question being whether those people took advantage of the phase transformation. To answer this question, the dehydration of synthetic goethite was studied by XRD coupled to Rietveld refinement. It was shown that no hydroxylated hematite is formed during

C. Vignaud; G MORIN

1998-01-01

110

XRD stress analysis of CVD diamond coatings on SiC substrates  

Microsoft Academic Search

The XRD Omega method was used to determine the residual stress in a CVD diamond coating deposited on a SiC substrate. The (400) plane of CVD diamond was used with a tilt angle (?) from 0 to 60 degrees. A compressive stress of ?130MPa with a standard deviation (SD) value of 28MPa was obtained. Stress results obtained from the indentation

S. Chowdhury; M. T. Laugier; J. Henry

2007-01-01

111

The multivariate statistical analysis and XRD analysis of pottery at Xigongqiao site  

Microsoft Academic Search

A series of pottery samples excavated from the Xigongqiao site in Tengzhou city of Shandong province was determined using inductively coupled plasma atomic emission spectrometry. Together with excavation data and archaeological analysis, the potential for provenance and technology of unearthed ancient pottery was studied by using multivariate statistical analysis and X-ray powder diffraction pattern (XRD) analysis. In order to characterize

Jiping Zhu; Jie Shan; Ping Qiua; Ying Qin; Changsui Wang; Deliang He; Bo Sun; Peihua Tong; Shuangcheng Wu

2004-01-01

112

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

113

HRTEM and EFTEM Observations of Matrix in the Oxidized CV3 Chondrite ALH 84028: Implications for the Origins of Matrix Olivines  

NASA Technical Reports Server (NTRS)

The determination of the nature, distribution, and origin of organic material in carbonaceous chondrites is fundamental to understanding early solar nebular conditions and the origin of life. Using a variety of extraction techniques, followed by detailed chemical analysis, an extensive suite of organic compounds has been identified in carbonaceous chondrites. These data have provided key information on the diversity and isotopic composition of the organic component in chondrites. However, one disadvantage of extraction techniques is that all information regarding the spatial distribution of the organics on a fine scale is lost. This is especially important for the insoluble macromolecular carbon, which constitutes approximately 70% of the carbon in carbonaceous chondrites such as Murchison. The distribution and mineralogical associations may provide important constraints on the possible origins of the carbonaceous material. Our previous studies of the CV3 chondrites Allende and Vigarano have demonstrated that energy filtered transmission electron microscopy (EFTEM), combined with high resolution TEM (HRTEM) are powerful tools for the in situ characterization of insoluble organic matter in carbonaceous chondrites. In this study, we have used SEM and TEM techniques to characterize the matrix mineralogy of the CV3 chondrite ALH 84028 and examine the distribution and mineralogical associations of carbon. We are especially interested in establishing whether the occurrence of poorly graphitized carbon (PGC), observed in Allende matrix olivines, is common to all oxidized CV3 chondrites or is a unique feature of Allende.

Abreu, Neyda M.; Brearley, Adrian J.

2003-01-01

114

An EFTEM/HRTEM high-resolution study of the near surface of labradorite feldspar altered at acid pH: evidence for interfacial dissolution-reprecipitation  

NASA Astrophysics Data System (ADS)

Using an approach combining high-resolution and energy-filtered transmission electron microscopy (HRTEM and EFTEM), we have studied with Å to nm-spatial resolution the interfacial region that delimits the near-surface altered zone and non-altered labradorite feldspar after dissolution under acid pH conditions. The interface is characterized by extremely sharp and spatially coincident changes in structure and chemistry. The 500-nm-thick altered zone is depleted in interstitial cations (Ca, Na, K) and Al, a framework element, whereas it is enriched in H, O, and Si. Modeling H+-alkali interdiffusion within a 500-nm-thick altered zone shows that volume interdiffusion cannot reproduce the sharp chemical interfaces measured by EFTEM. Based on these new data, we propose that the near-surface altered zone is a result of interfacial dissolution-reprecipitation, and not of preferential leaching of cations and interdiffusion with H+. This implies an intrinsic dissolution process that is stoichiometric, where the breaking of bonds and release of interstitial cations and framework elements (Al, Si, and O) to solution occur contemporaneously at equal relative rates from the original fluid-mineral interface.

Hellmann, R.; Penisson, J.-M.; Hervig, R. L.; Thomassin, J.-H.; Abrioux, M.-F.

115

The relationship between crystal morphology and XRD peak intensity on CaSO4·2H2O  

NASA Astrophysics Data System (ADS)

Each XRD peak intensity of CaSO4?2H2O crystals changes according to their morphologies. This research clarifies the relationship between XRD peak intensity and morphologies on CaSO4?2H2O crystals synthesized by reaction crystallization with various additives. As a result, as XRD relative intensity of (021) face increases, average longitude and aspect ratio decrease and needle-like or plate-like large crystals transform into granular microcrystals.

Inoue, Mikiyasu; Hirasawa, Izumi

2013-10-01

116

A Raman, IR and XRD analysis of the deterioration on historical monuments: Case study from Mexico  

NASA Astrophysics Data System (ADS)

Raman, infrared and XRD analysis have been applied to the examination of deterioration on historical monuments (Morelia, Mexico). Forty-three samples pyroclastic volcanic rocks (ignimbrites) have been studied, all originating from two ex-convents San Francisco and San Agustin, which were the first architectonic complexes in the city of Morelia. Several new mineral neoformation such as sulfates, carbonates, halides, and phosphates were identified in these samples with spectrometric and XRD technique. The observed Raman and infrared spectra are reported and some mineral compound assignments in unaltered and deteriorated volcanic rocks have been made. This survey is the first Raman and infrared spectrometric examination of the environmental mineralogy in Mexico under conditions of urban weathering that are characterized mainly by one secondary alteration formations of low scale.

Ostrooumov, Mikhail

2009-08-01

117

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

NASA Astrophysics Data System (ADS)

X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy measurements have been employed to investigate the (GdO)?(BO)?(ZnO) 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 ZnBO, ZnO(BO), Zn(BO) and GdBO. 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, BO and ZnO 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.; Pascuta, P.; Stefan, R.; Dan, V.; Pop, V.; Radulescu, D.

2013-11-01

118

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

119

High temperature XRD studies of nanoscale AgI CuI solid solutions  

NASA Astrophysics Data System (ADS)

A preliminary high-temperature X-ray diffraction (HT-XRD) study of the nanometer-sized solid solution phases in the AgI CuI system is reported through an extended range of temperatures (300 723K) covering phase transitions in both AgI and CuI. A major feature of this work is the observation of the coexistence of the zincblende and base-centred cubic phases of AgI over an extended range of temperatures the temperature width being a function of Cu content in the binary. The lattice parameters derived from HT-XRD data reflect systematics of phase transitions with progressive Cu substitution of AgI. The present results are discussed together with our earlier ionic conductivity, dilatometry and DSC data which have helped deduce phase diagrams for both the Ag-rich and Cu-rich regions of the binary.

Senthil Kumar, P.; Tyagi, A. K.; Sunandana, C. S.

2006-08-01

120

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

121

An in situ XRD investigation of singly and doubly promoted manganese oxide methane coupling catalysts  

Microsoft Academic Search

In situ X-ray diffraction (XRD) and concurrent measurements of catalytic performance have been used to characterize the solid phases present during various stages in the history of working methane coupling catalytic systems. Three such systems were studied: unpromoted, K-promoted, and KCl-promoted manganese oxide. In each case the effect of pulses of CHClâ on the activity, selectivity, and catalyst structure was

G. D. Moggridge; T. Rayment; R. M. Lambert

1992-01-01

122

XRD Patterns of Cathode Deposits Formed in Electric Arc Sputtering Zr-Me-Graphite Electrodes  

Microsoft Academic Search

XRD X-ray diffractogram patterns have been obtained for the deposits formed in electric arc sputtering of Zr-Me-graphite electrodes,\\u000a where Me is Ti, Mn, Fe, Co, Ni, Cu. The interlayer distances in the multi-wall carbon nanotubes, as the main component of\\u000a the deposit, slightly depend on the presence of metal Me. It has been shown that zirconium is present in the

Yu. M. Shulga; D. V. Schur; S. A. Baskakov; A. P. Simanovskiy; A. A. Rogozinskaya; A. A. Rogozinskiy; A. P. Mukhachev

123

Formation of carbon supported PtRu alloys: an XRD analysis  

Microsoft Academic Search

Carbon supported PtRu alloys were prepared by impregnation of Pt and Ru precursors on a porous carbon support, followed by reduction of the metals with Na2S2O4. After reduction, the samples were thermal treated in argon up to 700°C. The samples were characterized by atomic absorption (AAS) and X-ray diffraction (XRD) measurements. Before thermal treatment only carbon reflexions were visible in

E. Antolini; F. Cardellini

2001-01-01

124

Determination of grain size by XRD profile analysis and TEM counting in nano-structured Cu  

Microsoft Academic Search

In this work, a serial of pure copper sample with different grain sizes from nano- to micro-scale were prepared by sparkle plasma sintering (SPS) and following anneal treatment at 873K and 1073K, respectively. The grain size distributions of these samples were determined by both X-ray diffraction (XRD) profile analysis and transmission electronic microscope (TEM) micrograph counting. Although these two methods

Yong Zhong; Dehai Ping; Xiaoyan Song; Fuxing Yin

2009-01-01

125

A Comparative Study of Particle Size Dependency of IR and XRD Methods for Quartz Analysis  

Microsoft Academic Search

Quartz (SiO2) is considered a probable carcinogen. In order to enforce health and safety standards, techniques that can accurately determine the quartz content of materials are necessary. Currently, two techniques dominate quartz analysis—the infrared (IR) spectrophotometry method and the X-ray diffraction (XRD) method. Unfortunately, there are problems associated with these techniques, such as sample preparation and particle size effect. This

Ragula Bhaskar; Jianliang Li; Lijun Xu

1994-01-01

126

Mössbauer effect and XRD studies of iron-zinc binary alloys  

Microsoft Academic Search

Mössbauer spectroscopy and XRD were employed to characterize the microstructural properties of iron-zinc binary alloys between 0–31 at.% Fe. Samples were prepared with accuracies of ±0.5 at.% Fe, and the Mössbauer and lattice parameters were monitored as a function of iron concentration across each phase. Two iron sites were observed in the ? phase (18–31 at.% Fe), whose occupancies and

R. G. Grant; D. C. Cook

1994-01-01

127

The use of thermo-XRD-analysis in the study of organo-smectite complexes  

Microsoft Academic Search

Summary Thermo-XRD-analysis is applied to identify whether or not the adsorbed organic species penetrates into the interlayer space of the smectites mineral. In this technique an oriented smectite sample is gradually heated to temperatures above the irreversible dehydration of the clay, and after each thermal treatment is diffracted by X-ray at ambient conditions. In the thermal treatment of organo-clays, under

S. Yariv; I. Lapides

2005-01-01

128

A new simultaneous apparatus for X-ray diffractometry and differential scanning calorimetry (XRD-DSC)  

Microsoft Academic Search

An instrument was developed for performing simultaneous X-ray diffractometric and differential scanning calorimetric (XRD-DSC) measurement using a power compensation DSC (pc-DSC). The feasibility of the technique is demonstrated by examining the thermal dehydration measurement of zinc formate dihydrate (Zn(HCO2)2·2H2O). The DSC curve shows apparent double endothermic peaks during the dehydration process, while X-ray diffraction analysis indicated that the resulting anhydrous

Tadashi Arii; Akira Kishi; Yuji Kobayashi

1999-01-01

129

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

Microsoft Academic Search

Diamond-like carbon films were deposited by electrolysis of a water–ethanol solution on Cu at low voltages (60–100V) at 2mm 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 ?1580cm?1.

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

2010-01-01

130

Internal stress in MPCVD diamond films on the Si substrate based on XRD line shape  

Microsoft Academic Search

The diamond films adherent to Si substrate are deposited with the microwave plasma CVD (MPCVD) at microwave powers of 6000\\u000a W and 4000 W from 6 h to 10 h, respectively, the internal stresses of the films are measured by XRD. Spectral peak shift and\\u000a widening are applied to calculate the magnitudes of macro and micro stresses. The results show

Xiao-Wei Li; Cui-Ping Li; Cheng-Yao Gao; Meng-Xue Huang; Bao-He Yang

2009-01-01

131

Microstructural characterization of hematite during wet and dry millings using Rietveld and XRD line profile analyses  

Microsoft Academic Search

The effects of extended milling in a stirred media mill and a tumbling mill on the structural changes in hematite have been examined using a combination of particle size analysis, BET surface areas, X-ray diffraction (XRD), thermal (TG and DSC) and FTIR measurements. Rietveld's whole profile fitting based on crystal structure refinement and the Warren–Averbach's method of X-ray line profile

Parviz Pourghahramani; Erguen Altin; Madhusudhan Rao Mallembakam; Wolfgang Peukert; Eric Forssberg

2008-01-01

132

Mechanical Properties of Polycrystalline Titanium Nitride Films Measured by XRD Tensile Testing  

Microsoft Academic Search

This paper describes measurement of mechanical properties of micron-thin polycrystalline titanium nitride (TiN) films. We developed a novel tensile test technique that can directly measure lateral elastic strain of a microscale single\\/poly-crystalline specimen by means of X-ray diffraction (XRD), which enables evaluation of not only Young's modulus but also Poisson's ratio of TiN films. TiN films having thicknesses of 0.5

Takahiro Namazu; Shozo Inoue; Hideki Takemoto; Keiji Koterazawa

2005-01-01

133

Determination of A-site deficiency in lanthanum manganite by XRD intensity ratio  

Microsoft Academic Search

A method based on the X-ray diffraction intensity ratio was developed to determine the maximum deficiency that the perovskite-structured La1?xMnO3±? can accommodate at the A-site. Computer simulation predicts that the intensity ratio of (024) and (012) reflections for La1?xMnO3±? in hexagonal setting increases with increasing the La deficiency x. XRD analysis shows that with increasing x until 0.09, the ratio

Yanbo Zuo; Jianheng Li; Jianxin Yi; Zhongbing Wang; Chusheng Chen

2008-01-01

134

Comparative XRD analysis ettringite originating from pozzolan and from portland cement  

Microsoft Academic Search

The ettringite is often formed when concrete is attacked by sulphatic waters. In this investigation, a semi-quantitative analysis and study of the ettringite (2? = 9.08 °) in the solid phase of the Fratini test was made by XRD. The cements P-1 (14.11% C3A) P-31 (7.6% C3A) and PY-6 (0.00% C3A), five pozzolans, D,O,A,C and M and five mixed cements

Rafael Talero

1996-01-01

135

Study the oxidation kinetics of uranium using XRD and Rietveld method  

NASA Astrophysics Data System (ADS)

The surface oxidation of uranium metal has been studied by X-ray diffraction (XRD) and Rietveld method in the range of 50~300°C in air. The oxidation processes are analyzed by XRD to determine the extent of surface oxidation and the oxide structure. The dynamics expression for the formation of UO2 was derived. At the beginning, the dynamic expression was nonlinear, but switched to linear subsequently for uranium in air and humid oxygen. That is, the growth kinetics of UO2 can be divided into two stages: nonlinear portion and linear portion. Using the kinetic data of linear portion, the activation energy of reaction between uranium and air was calculated about 46.0 kJ/mol. However the content of oxide as a function of time was linear in humid helium ambience. Contrast the dynamics results, it prove that the absence of oxygen would accelerate the corrosion rate of uranium in the humid gas. We can find that the XRD and Rietveld method are a useful convenient method to estimate the kinetics and thermodynamics of solid-gas reaction.

Zhang, Yanzhi; Guan, Weijun; Wang, Qinguo; Wang, Xiaolin; Lai, Xinchun; Shuai, Maobing

2010-03-01

136

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

137

In-Situ Cold Temperature XRD of Calcium Phosphate Produced From Organic Phosphoric Acid  

NASA Astrophysics Data System (ADS)

In this study, we synthesized calcium phosphate from an organic phosphoric acid, diethylhexyl phosphoric acid (DEHPA) and calcium hydroxide solution. The reaction involves a sol-gel process with a whitish gel formed. In-situ XRD analysis was then performed on the sample from room temperature to -140° C. At room the XRD diffractogram shows the sample as an amorphous material and as the temperature was further lowered sharp peaks begins to form indicating that the material had becomes crystalline. The peaks were identified to be that calcium hydrogen phosphate (Ca(H2PO4)2) and this indicates that there is no hydroxyl group removal during the cooling process. The relative crystallinity values obtained for the different cooling temperatures show a slow exponential increase on the initial cooling of 0 to -100° C and at further cooling temperatures resulted fast and linear process. Also unlike the in-situ XRD analysis performs at high temperature no phase transformation occurred at this low temperature.

Yusoff, M. S. Meor; Paulus, Wilfred; Muslimin, Masliana

2010-01-01

138

Synthesis and characterization of low-OH?fluor-chlorapatite: A single-crystal XRD and NMR spectroscopic study  

SciTech Connect

Los-OH apatite of the compositional range Ca{sub 4.99-5.06}(PO{sub 4}){sub 2.98-3.00}F{sub 0.51-0.48}Cl{sub 0.38-0.36}OH{sub 0.14-0.12} was synthesized and characterized structurally by synchrotron-based single-crystal X-ray diffraction (XRD), and multiple nuclear magnetic resonance (NMR) spectroscopic techniques. the average structure is hexagonal with space group P6{sub 3}/m. The presence of scattering in the single-crystal diffraction data set, which is incommensurate within the average hexagonal structure, suggests the presence of localized short-range monoclinic domains. Complex lineshapes in the {sup 31}P and {sup 19}F MAS NMR spectra are also consistent with the presence of an incommensurate phase. No evidence was detected for splitting of the Ca2 site into two distinct sites (as had been previously reported for hexagonal ternary apatities). Structure refinement and {sup 19}F{l_brace}{sup 35}Cl{r_brace} TRAPDOR NMR experiments verified intercolumnal neighboring of F and Cl atoms (inter-column distance of 2.62 {angstrom}) within this low-OH{sup -} apatite suggesting that long-range neighboring of F and Cl within the apatite anion channels is feasible.

McCubbin, Francis M.; Mason, Harris E.; Park, Hyunsoo; Phillips, Brian L.; Parise, John B.; Nekvasil, Hanna; Lindsley, Donald H. (SBU)

2008-12-12

139

Investigation of Mg and Zn doped 45S5 bioactive materials by XRD, FTIR and SEM techniques  

NASA Astrophysics Data System (ADS)

Magnesium and zinc doped 45S5 samples were prepared in the laboratory by sol gel technique., Structural properties of the samples have been studied by XRD, FTIR and SEM techniques. Both FTIR and XRD data indicate the primary bioactive behavior of the samples. Presented results may be useful to improve the antibacterial as well as osteoblast properties of the currently available bioactive materials.

Anand, Vikas; Singh, K. J.; Kaur, Kulwinder

2014-04-01

140

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

141

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

142

Dissolution, solubility, XRD, and DSC studies on flurbiprofen-nicotinamide solid dispersions.  

PubMed

Flurbiprofen-nicotinamide solid dispersions were prepared by the fusion method. The solid dispersions were evaluated for dissolution rate. The drug-carrier interaction in the liquid and solid states were studied by using phase solubility analysis, phase diagram, X-ray diffraction (XRD), and differential scanning calorimentry (DSC). Solid dispersions gave fast and rapid dissolution of flurbiprofen compared with the pure drug and the physical mixture. Phase diagram and DSC indicated that flurbiprofen and nicotinamide form a eutectic mixture. The aqueous solubility of flurbiprofen was enhanced in the presence of nicotinamide. PMID:16093207

Varma, M M; Pandi, J K

2005-05-01

143

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

144

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

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

145

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

SciTech Connect

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

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

2012-11-19

146

High Pressure XRD Structural Study of Intermetallic Hydrogen Storage Material ZrFe2  

NASA Astrophysics Data System (ADS)

Intermetallic compounds show high hydrogen sorption capacities when pressurized with hydrogen. Further, they are also used in hydride compressors [1]. The structure of intermetallic ZrFe2, which can contain about 1.7 wt/% hydrogen around 0.18 GPa, was studied using XRD at high pressures up to 47 GPa using a diamond anvil cell and synchrotron x-rays. The cubic Fd3m Laves phase is found to be stable and the bulk modulus was found to be 163.5 GPa which compares well with other intermetallics. The variation of unit structural parameters and the equation of state are discussed.

Antonio, Daniel; Kumar, Ravhi; Cornelius, Andrew

2011-03-01

147

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

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

148

Synthesis and magnetic properties of Fe{sub 3}O{sub 4} nanoparticles  

SciTech Connect

Ferromagnetic Fe{sub 3}O{sub 4} nanoparticles with diameter of {approx}27 nm were prepared by a hydrothermal route in the presence of a surfactant, sodium bis(2-ethylhexyl)sulfosuccinate (AOT). The as-synthesized product was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The hysteresis loops of the iron oxide nanoparticles were measured using a physical property measuring system (PPMS), and the results showed a superparamagnetic behavior at room temperature.

Zheng Yuanhui [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Graduate School of Chinese Academy of Sciences, Yangqiao West Road 155, Fuzhou, Fujian 350002 (China); Cheng Yao [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Graduate School of Chinese Academy of Sciences, Yangqiao West Road 155, Fuzhou, Fujian 350002 (China); Bao Feng [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Graduate School of Chinese Academy of Sciences, Yangqiao West Road 155, Fuzhou, Fujian 350002 (China); Wang Yuansheng [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Graduate School of Chinese Academy of Sciences, Yangqiao West Road 155, Fuzhou, Fujian 350002 (China)]. E-mail: yswang@fjirsm.ac.cn

2006-03-09

149

Highly ordered magnetic mesoporous silicas for effective elimination of carbon monoxide  

NASA Astrophysics Data System (ADS)

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

Lee, Jiho; Ho Chang, Jeong

2012-04-01

150

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

151

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

152

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

PubMed

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

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

2013-12-01

153

XRD and EPR structural investigation of some zinc borate glasses doped with iron ions  

NASA Astrophysics Data System (ADS)

Glasses in the system xFe2O3·(100-x) [45ZnO·55B2O3] (0?x?10 mol%) have been prepared by melting at 1200 °C and rapidly cooling at room temperature. The obtained samples were submitted to an additional thermal treatment at 570 °C for 12 h in order to relax the glass structure as well as to improve the local order. The as cast and heat treated samples were investigated using X-ray diffraction (XRD) and electron paramagnetic resonance (EPR) measurements. The XRD patterns of all the studied samples show their vitreous nature. Structural modifications occurring in the heat treated samples compared to the untreated ones have been pointed out. EPR spectra of untreated and heat treated samples revealed resonance absorptions centered at g?2.0, g?4.3 and g?6.4. The compositional variation of the line intensity and linewidth of the absorptions from g?4.3 and g?2.0 have been interpreted in terms of the variation in the concentration of the Fe3+ ions and the interaction between the iron ions. The EPR spectra of the untreated samples containing 5 mol% Fe2O3 have been studied at different temperatures (110-290 K). The line intensity of the resonance signals decreases with increase in temperature whereas the linewidth is found to be independent of temperature. It was also found that the temperature variation of reciprocal line intensity obeys the Boltzmann law.

Stefan, Razvan; Pascuta, Petru; Popa, Adriana; Raita, Oana; Indrea, Emil; Culea, Eugen

2012-02-01

154

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

NASA Astrophysics Data System (ADS)

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

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

2003-04-01

155

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

156

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

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

157

EXAFS and XRD characterization of palladium sorbents for high temperature mercury capture from fuel gas.  

PubMed

Removal of pollutants such as mercury at elevated temperatures provides improvements in the overall thermal efficiency during the process of coal gasification. The two high temperature sorbents studied were 5 wt% Pd/Al(2)O(3) and 5 wt% Pd/SiO(2): materials shown to have significantly different Hg adsorption capacities. A combination of XRD and EXAFS has been used to characterize the Pd-Hg alloy formed when these Pd-based sorbents were exposed to fuel gas (CO, CO(2), H(2)) containing Hg vapour at 204 degrees C. Significant differences were found in the nature of the alloy formed on the two sorbents following Hg exposure. The Pd/Al(2)O(3) sorbent produced a single homogeneous solid solution of Pd-Hg whilst the silica-supported Pd produced an alloy of varying composition. PMID:20023826

Poulston, Stephen; Hyde, Timothy I; Hamilton, Hugh; Mathon, Olivier; Prestipino, Carmelo; Sankar, Gopinathan; Smith, Andrew W J

2010-01-14

158

Determination of A-site deficiency in lanthanum manganite by XRD intensity ratio  

NASA Astrophysics Data System (ADS)

A method based on the X-ray diffraction intensity ratio was developed to determine the maximum deficiency that the perovskite-structured La 1-xMnO 3±? can accommodate at the A-site. Computer simulation predicts that the intensity ratio of (024) and (012) reflections for La 1-xMnO 3±? in hexagonal setting increases with increasing the La deficiency x. XRD analysis shows that with increasing x until 0.09, the ratio increases as predicted, then levels off with further increase in x. An abrupt change in electrical conductivity is also observed at x of ˜0.10. It is concluded that the maximum deficiency lies in between 0.09 and 0.10 for La 1-xMnO 3±?. The methodology presented in this paper in principle can be applied to other perovskite-structured materials.

Zuo, Yanbo; Li, Jianheng; Yi, Jianxin; Wang, Zhongbing; Chen, Chusheng

2008-04-01

159

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

NASA Astrophysics Data System (ADS)

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 presence of Mg 2+ in the grown doped TGSP crystals. Dielectric constant and dielectric loss of undoped and magnesium sulfate-doped TGSP crystals were measured for various frequencies and temperatures. It is observed from the studies that solubility and dielectric properties like dielectric constant and dielectric loss increase when TGSP crystal is added with magnesium sulfate. Thermogravimetric and differential thermal analyses (TG/DTA) on the grown crystals have been carried out. The effect of impurity (magnesium sulfate) on structural, electrical and thermal properties of TGSP crystals has been investigated.

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

2008-12-01

160

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

PubMed

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

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

2013-10-01

161

Characterization of stabilized\\/solidified refinery oily sludge and incinerated refinery sludge with cement using XRD, SEM and EXAFS  

Microsoft Academic Search

Solidification\\/stabilization (S\\/S) of refinery oily sludge and incinerated oily sludge (ash) with cement type I42.5 and II42.5 was investigated using, X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) combined with Energy Dispersive Spectroscopy (EDS) and Extended X-ray Absorption Fine Structure (EXAFS). The results showed that delayed ettringite formation (DEF) and major cement hydration reactions occurred. XRD analysis of S\\/S oily sludge

Athanasios K. Karamalidis; Vasileios Psycharis; Ioannis Nicolis; Eleni Pavlidou; Simone Bénazeth; Evangelos A. Voudrias

2008-01-01

162

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

Microsoft Academic Search

X-ray absorption fine-structure (XAFS) spectroscopy, micro-X-ray fluorescence (μXRF), and micro-X-ray diffraction (μXRD) 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⁻¹). Linear combination fitting of the XAFS data, supported by μXRF and μXRD, shows that Pb is complexed in a variety of molecular environments,

L MacLean; S Beauchemin; P Rasmussen

2011-01-01

163

Characterization of quenched high pressure phases in CaSiO3 system by XRD and 29Si NMR  

Microsoft Academic Search

We have studied quenched high pressure phases in the CaSiO3 system by x-ray diffraction (XRD) and 29Si MAS NMR, XRD study of the previously reported “?-CaSiO3 phase” synthesized at 12 GPa and 1500 °C reveals that it is actually a mixture of ?-Ca2SiO4 (larnite) and a previously unknown CaSi2O5 phase. This result is supported by the 29Si NMR spectra. Furthermore,

Masami Kanzaki; Jonathan F. Stebbins; Xianyu Xue

1991-01-01

164

Characterization of mullite in silicoaluminous fly ash by XRD, TEM, and 29Si MAS NMR  

Microsoft Academic Search

Mullite contained in a silicoaluminous fly ash (originating from power plant of La Maxe, near Metz in the east of France) issue from bituminous coal combustion has been studied by X-ray diffraction, nuclear magnetic resonance of 29Si spinning at magic angle, and transmission electron microscopy linked with energy-dispersive spectroscopy. By using results from X-ray diffraction [1] and nuclear magnetic resonance

S. Gomes; M. François

2000-01-01

165

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

166

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

167

A new mesoporous FeBO 3 material having dominant surface magnetism  

Microsoft Academic Search

A new mesoporous iron(III) borate material has been synthesized hydrothermally by using supramolecular assembly of cationic (cetyltrimethylammonium bromide, CTAB) or anionic (sodiumdodecyl sulfate, SDS) surfactant as structure directing agent (SDA) during co-condensation of Fe(III) and H3BO3 under controlled pH condition. Powder X-ray diffraction, N2 sorption, HRTEM, FE-SEM-EDS, AAS, FT-IR and UV–Vis spectroscopic tools, Mössbauer and magnetization measurements are used to

Swapan K. Das; Mahasweta Nandi; Saurav Giri; Asim Bhaumik

2009-01-01

168

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

169

?-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

170

Investigation by XRF and XRD of Zn and Fe in Fex Zn1-x thin films  

NASA Astrophysics Data System (ADS)

FexZn1-x alloys were electrochemically deposited on aluminum substrates from a sulfate bath. The K?/K? x-ray intensity ratios of Zn and Fe in FexZn1-x thin films have been experimentally studied. The energy dispersive x-ray fluorescence (EDXRF) technique was used to measure K x-ray photons. Samples were excited by using 59.5 keV photons emitted by a 50 mCi 241Am radioactive source. The emitted K x-rays were detected by an Ultra-LEGe detector having a resolution of 150 eV at 5.9 keV. In addition, the effect of bath composition on the phase structure was investigated by x-ray diffraction (XRD) analysis. The composition of the thin films was analyzed by atomic absorption spectrometry analysis. Iron content was shown to strongly affect the structure of Zn-Fe alloys. It was found that the K-shell x-ray intensity ratio changed in FexZn1-x thin films for different values of x. The reason for this change may be that the electronegativity of iron is higher than that of zinc and that electron transfer from zinc to the outermost orbital of iron occurs. In conclusion, in FexZn1-x thin films, intensity ratio increases with increasing concentration of Zn but decreases with increasing concentration of Fe.

Sö?üt, Ö.; Bütün, H.; Karahan, ?. H.; T?ra?o?lu, E.; Apayd?n, G.

2008-12-01

171

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

PubMed

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

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

2013-11-01

172

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

173

A high pressure XRD setup at ADXRD beamline (BL-12) on Indus-2  

NASA Astrophysics Data System (ADS)

A high pressure XRD measurement setup in the angle dispersive geometry has been setup in the Angle Dispersive X-ray diffraction beamline (BL-12) in Indus-2 synchrotron facility. The X-Ray beam is collimated inside the diamond anvil cell (DAC) using a pair of cross-slit collimators and 100 micron orifice in a 400 micron thick Ta sheet. With the use of an adaptive optics to ensure a converging beam at the sample position, the need of an x-ray beam collimator is eliminated making the alignment of the DAC quite easy. The alignment of the DAC with respect to the incident x-ray beam is made by placing it on a computer controlled sample mounting and alignment stage developed specifically for this setup. Interactive software has been developed to make the alignment of the X-ray through the DAC very easy and accurate. NIST standard LaB6 powder was used for test runs, and a few fine pieces of gold served as pressure calibrator. The data was recorded on a MAR345 Image plate detector.

Ganguli, Tapas; Sinha, A. K.; Narayana, Chandrabhas; Upadhyay, Anuj; Singh, M. N.; Saxena, P.; Dubey, V. K.; Singh, I. J.; Raja, Sendhil; Vora, H. S.; Deb, S. K.

2013-03-01

174

[Infrared spectra and XRD characteristics of alunite in the Zijinshan gold-copper deposit].  

PubMed

The structural characteristics and composition of alunite in the Zijinshan gold-copper deposit were studied by infrared absorption spectroscopy and X-ray powder diffraction analysis. The results show that infrared spectral absorption peaks, the growth degree of crystal faces (006) and (004), and crystal cell parameters of the alunite display gradually decreasing trend from the crater to northwest along the metallogenic belt. Combined with electron probe analysis results, we go further and obtain that the alunite mainly belongs to potassium alunite, and the characteristics of infrared spectra and XRD of the alunite mainly have relation to the content of potassium of the alunite in different parts of volcanic mechanism. Near the crater, with higher temperature, it is helpful for the isomorphism replacement between sodium and potassium, the content of sodium is higher and the content of potassium is lower relatively in the alunite; and away from the crater, the temperature is relatively lower, it is against the isomorphism replacement between sodium and potassium, the content of sodium is lower, and the content of potassium is higher relatively in the alunite. PMID:24059212

Wang, Cui-Zhi; Zhang, Wen-Yuan

2013-07-01

175

Structural Characterization of Ni-Substituted Hexaaluminate Catalysts Using EXAFS, XANES, XPS, XRD, and TPR  

SciTech Connect

The structure of five Ni-substituted Ba{sub 0.75}Ni{sub y}Al{sub 12-y}O{sub 19-{delta}} hexaaluminate catalysts at various Ni loadings (y = 0.2, 0.4, 0.6, 0.8 and 1.0) was investigated using EXAFS, XANES, XPS, XRD, and TPR. As Ni-substitution into the hexaaluminate lattice is increased, the unit cell dimension decreases along the c axis. This systematic change is consistent with Ni substitution for Al{sup 3+} in the hexaaluminate crystalline structure. XANES analysis suggests that Ni-O bonding is stronger for Ni substituted into the hexaaluminate lattice, relative to that of bulk NiO. The average coordination numbers obtained from EXAFS indicate that Ni is preferentially exchanging with tetrahedrally coordinated Al{sup 3+} in the structure which predominates in regions of the hexaaluminate unit cell near the mirror plane. It is at these sites that, preferential substitution of Ni{sup 2+} likely occurs to minimize strain in the crystalline lattice.

Gardner, J.; Spivey, J; Kugler, E; Campos, A; Hissam, J; Roy, A

2010-01-01

176

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

177

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

178

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

179

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

180

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

181

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

182

Transient Measurements Under Simulated Mantle Conditions - Simultaneous DTF-Ultrasonic Interferometry, X-Radiography, XRD  

NASA Astrophysics Data System (ADS)

The interpretation of seismic data from the Earth's deep interior requires measurements of the physical properties of Earth materials under experimental simulated mantle conditions. Elastic wave velocity measurement by ultrasonic interferometry is an important tool for the determination of the elastic properties in multi-anvil devices. Whereas the classical sweep method is very time-consuming, the ultrasonic data transfer function technique (DTF), simultaneously generating all the frequencies used in the experiment, first described by Li et al. (2002), requires just few seconds to save the response of the system. The success of the technique substantially depends on the excitation function and the resolution used for saving the DTF (Mueller et al., 2004a). Background discussion as well as high pressure AƒA_A,A¿A,A 1/2 high temperature results demonstrate how to optimize the technique. All Ultrasonic interferometry allows highly precise travel time measurement at a sample enclosed in a high-pressure multi-anvil device. But under high pressure conditions the influence of sample deformation on the frequencies for destructive and constructive interference used for the evaluation of the elastic properties might be stronger than that from the shift of the elastic moduli. Consequently ultrasonic interferometry requires the exact sample length measurement under in situ conditions. X-ray imaging using brillant synchrotron radiation, called X-radiography, produces grey-scale images of the sample under in situ conditions by converting the X-ray image to an optical one by a CE-YAG-crystal. Saving the optical image by a CCD-camera after redirection by a mirrow, also requires few seconds. To derive the sample length, the different brightness of sample, buffer rod and reflector at the electronic image is evaluated (Mueller et al., 2004b). Contrary to XRD measurements, imaging the sample by X-rays requires a beam diameter larger than the sample length. Therefore the fixed primary slits of Max80 were exchanged by 4-blade high precision slits of Advanced Design Consulting, Inc. Some recent results on the non-quenchable high-P AƒA_A,A¿A,A 1/2 low-P clinoenstatite transition and to the quartz-coesite transition will be given to discuss the different interferometric techniques, including the XRD-data and X-radiography results, necessary to detect the phase transitions under in situ conditions and to measure the sample deformation. Li, B.; Chen, K.; Kung, J.; Liebermann, R.C.; Weidner, D.J., J. Phys.: Condens. Matter 14, 11337-11342, (2002). Mueller, H.J.; Lathe, C.; Wunder, B., In: J. Chen, Y. Wang, T. Duffy, G. Shen, L. Dobrzhinetskaya (eds.), Frontiers in High Pressure Research, Elsevier Science, submitted, (2004a). Mueller, H.J.; Schilling, F.R.; Lathe, C.; Lauterjung, J., In: J. Chen, Y. Wang, T. Duffy, G. Shen, L. Dobrzhinetskaya (eds.), Frontiers in High Pressure Research, Elsevier Science, in press, (2004b).

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

2004-12-01

183

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

184

Magnetic measurements on ?-CS2U4O12  

NASA Astrophysics Data System (ADS)

Magnetic and XRD measurements on ?-CS2U4O12 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; Misra, N. L.; Sastry, P. U.; Dube, V.; Ravikumar, G.

2014-04-01

185

Nanoscale investigation of thin film perpendicular magnetic recording media  

NASA Astrophysics Data System (ADS)

The HCP CoCrPtO Perpendicular magnetic recording media are attractive to achieve recording densities over 1 Tbit/in2 owing to their low media noise characteristics. Structural refinement is critical to the development of ultra-high recording density perpendicular media with low noise. The grain size and film thickness are on a scale of 8 nm and 20 nm or less, respectively, so it is evident that high-resolution transmission electron microscopy (HRTEM) is the most powerful method to characterize the nanoscale structural features and elucidate their effects on the magnetic recording media performance. In CoCrPtO perpendicular media, one of the objectives as far as the structure is concerned, is to obtain media of magnetically decoupled grains. This can be done by isolating the Co-rich magnetic grains from each other with non-magnetic oxygen-rich grain boundaries. In the present study, CoCrPtO media were prepared by systematically varying the thickness and oxygen content of the magnetic layer, and their effect on the resulting film structure was investigated by HRTEM. Nano-probe energy dispersive X-ray spectroscopy (EDS) combined with HRTEM was used to perform compositional analysis and study the segregation effects. Higher oxygen incorporation was effective to form a well-isolated grain structure with oxygen-rich grain boundaries. However, non-uniform film structure with high stacking fault density was also observed with high oxygen content. More precise control on the film structure of the perpendicular media often involves template layers such as interlayers and seedlayers. The role of these layers is not limited to the enhancement of the preferred vertical c-axis orientation but can be extended to the control of the grain size, grain size distribution, and grain isolation in the magnetic film. The effects of Ta/Ru template layers on the structural and magnetic properties of the magnetic film were investigated. Moreover, a novel Ru/Ru+(metal oxide) interlayer structure for further inter-granular exchange decoupling in the magnetic film was introduced and evaluated. The formation of a small and isolated grain structure on the surface of the interlayer was achieved by the addition of a Ru+(metal oxide) on a conventional Ru interlayer, which resulted in further grain isolation in the magnetic film.

Kwon, Unoh

186

XRD and FTIR studies on a new solid electrolyte system containing Ag3PO4 and SbI3  

NASA Astrophysics Data System (ADS)

A new solid electrolyte system, 60 mole % Ag3PO4 - 40 mole % SbI3 has been prepared by melt-quenching method and characterized by XRD and FTIR techniques. The observed results tend to confirm the formation of room temperature fast ionic phases.

Suthanthiraraj, S. Austin; Sarumathi, R.

2012-06-01

187

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

188

Review of XRD-based quantitative analyses of clay minerals in soils: the suitability of mineral intensity factors  

Microsoft Academic Search

The determination of the types and relative amounts of the minerals present in soil forms an essential component of most soil characterization efforts. This paper reviews protocols for XRD-based quantitative clay mineral analysis in soils, with emphasis on methods using mineral intensity factors in combination with the so-called 100% approach. We summarize methodological differences and characteristic features and give information

Maren Kahle; Markus Kleber; Reinhold Jahn

2002-01-01

189

Epitaxial growth of In2O3(100) on Y-stabilised ZrO2(100) by O-plasma assisted molecular beam epitaxy: a study by HRTEM and XPS.  

NASA Astrophysics Data System (ADS)

Thin films of In2O3 have been grown on Y-stabilised ZrO2(100) by radiofrequency oxygen plasma assisted molecular beam epitaxy with a substrate temperature of 650 C. Ordered epitaxial growth was confirmed by HRTEM and selected area electron diffraction taken across the interface between the substrate and the epilayer. Excellent crystalline order was preserved up to the surface of the films. The valence band onset in the X-ray photoemission spectra of the epitaxial films was found at 2.90 eV relative to the Fermi energy. The discrepancy between this value and the widely quoted value of 3.75 eV for the bandgap will be discussed in relation to recent theoretical work [1]. [1] A. Walsh et al., Phys. Rev. Lett. submitted.

Bourlange, Anne; Payne, David; Egdell, Russell; Foord, John; Dobson, Peter; Hutchison, John

2008-03-01

190

A general method for the recovery of pure powder XRD patterns from complex mixtures using no a priori information  

Microsoft Academic Search

The recovery of pure component spectra from multi-component mixtures is one of the most common analytical problems in the chemical sciences. In cases where separation of the unknown components is not possible, the problem is often intractable. In materials science research, X-ray diffraction (XRD) and particularly X-ray powder diffraction (XRPD) are perhaps the primary characterization tools. Recently, we introduced band-target

Liangfeng Guo; Fethi Kooli; Marc Garland

2004-01-01

191

Transformation of meta-stable calcium silicate hydrates to tobermorite: reaction kinetics and molecular structure from XRD and NMR spectroscopy  

Microsoft Academic Search

Understanding the integrity of well-bore systems that are lined with Portland-based cements is critical to the successful storage of sequestered CO2 in gas and oil reservoirs. As a first step, we investigate reaction rates and mechanistic pathways for cement mineral growth in the absence of CO2 by coupling water chemistry with XRD and NMR spectroscopic data. We find that semi-crystalline

Jacqueline R Houston; Robert S Maxwell; Susan A Carroll

2009-01-01

192

In-situ XRD study of the succinonitrile–lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) phase diagram  

Microsoft Academic Search

The salt lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) when dissolved in plastic crystal succinonitrile has been demonstrated to have particularly good conductivity even at room temperature. In-situ X-ray diffraction (XRD) measurements have previously proved invaluable in interpreting the differential scanning calorimetry (DSC) behavior, but the practical lower temperature limit of approximately ?45°C was higher than the ?100°C starting temperature of the DSC measurements,

P. S. Whitfield; A. Abouimrane; I. J. Davidson

2010-01-01

193

Temperature dependence of the cation distribution in nickel aluminate (NiAl2O4) 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

194

In situ NMR and XRD studies of the growth mechanism of SBA-1.  

PubMed

In situ 17O, 14N and 29Si nuclear magnetic resonance (NMR) coupled with in situ energy dispersive X-ray diffraction (EDXRD) have been used to investigate the growth of the siliceous mesoporous material, SBA-1, synthesised under acidic conditions from a micellar solution of the surfactant hexadecyltriethylammonium bromide (HTEAB) and tetraethylorthosilicate (TEOS). For the last decade, the mechanism of growth of such materials has been thought to be driven by electrostatic interactions described as a co-assembly process between the silica species (I+) and the micelles (S(+)X(-)). However, this postulated model referred to as the "charge density matching model" has never been fully supported by experimental data for the acidic syntheses. We have carried out a detailed in situ study which challenges the so-called S(+)X(-)I(+) pathway and instead suggests that a salting-out effect coupled with a drastic change in the water activity are responsible for the composite I(1)3 (SBA-1 space group Pm3n) mesophase precipitation. Substantial reorganisation of the precipitated phase then results in the final structure. PMID:19787948

Egger, C C; Anderson, M W; Tiddy, G J T; Casci, J L

2005-04-21

195

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

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

196

Whisker formation behavior on tin film plated in high magnetic field  

Microsoft Academic Search

High magnetic field was applied during Sn plating treatment for brass to change crystal orientation in the plating film. After prolonged heat treatment at 323 K, its effect on the formation of Sn whisker was investigated by scanning electron microscopic observations and X-ray diffraction (XRD). The XRD pattern of the film varied with the angle between the substrate and the

Keisuke TSUTSUMI; Yuichi IWANE; Yasuhiro MORIZONO; Toshiyuki KOZUKA; Yasuhide OHNO

2006-01-01

197

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

198

Preparation, thermal, XRD, chemical and FTIR spectral analysis of NiMn 2 O 4 nanoparticles and respective precursor  

Microsoft Academic Search

Metal carboxylato-hydrazinates are very good precursors for the synthesis of metal as well as mixed metal oxides as these\\u000a decompose to nanosized oxides with high surface area most of the times at comparatively lower temperatures. In the present\\u000a study one such novel precursor nickel manganese fumarato-hydrazinate (NiMn2(C4H2O4)3·6N2H4) has been prepared and characterized by XRD, FTIR and chemical analysis. The thermal

S. Y. Sawant; V. M. S. Verenkar; S. C. Mojumdar

2007-01-01

199

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

200

Ex-situ XRD studies of CoSb 3 compound as the anode material for lithium ion batteries  

Microsoft Academic Search

The skutterudite-type CoSb3 alloy was prepared using levitation melting. The electrochemical properties of CoSb3 were investigated using Li ion model cells, Li\\/LiPF6(EC+DMC)\\/CoSb3. It was found that the first reversible capacity is about 420 mA h g?1. Ex-situ XRD (X-ray diffraction) experiments have been used to characterize the electrochemical lithiation and de-lithiation mechanism of CoSb3 alloy. The results revealed that when

Jian Xie; Xinbing Zhao; Gaoshao Cao; Yaodong Zhong; Mingjian Zhao

2003-01-01

201

Rapid characterisation of archaeological midden components using FT-IR spectroscopy, SEM-EDX and micro-XRD.  

PubMed

Samples taken from middens at the Neolithic site of Catalhöyük in Turkey have been analysed using IR spectroscopy backed up by powder XRD and SEM-EDX. Microcomponents studied include fossil hackberries (providing evidence of ancient diet and seasonality), mineral nodules (providing evidence of post-depositional change) and phytoliths (mineralised plant cells, providing evidence of usage of plant species). Finely laminated ashy deposits have also been investigated allowing chemical and mineralogical variations to be explored. It is found that many layers which appear visually to be quite distinctive have, in fact, very similar mineralogy. PMID:19268629

Shillito, Lisa-Marie; Almond, Matthew J; Nicholson, James; Pantos, Manolis; Matthews, Wendy

2009-07-01

202

A comprehensive review of the XRD data of the primary and secondary phases present in the BSCCO superconductor system  

SciTech Connect

X-ray powder patterns for the phases in the CaO-SrO-PbO ternary system, along with the corresponding crystal structures, were obtained from the literature and from the Powder Diffraction File (PDF). Available X-ray diffraction (XRD) patterns were compared with each other and, when possible, with a calculated pattern for each phase, yielding a recommended reference pattern. The simulated powder patterns presented here deal with the phases found within the (Ca,Sr){sub 2}PbO{sub 4} solid solution series and are recommended for the PDF.

Reardon, B.J.; Hubbard, C.R.

1992-02-01

203

Magnetic nanoparticles fixed on the surface of detonation nanodiamond microgranules  

Microsoft Academic Search

Conglomerates formed out of aggregated nanodiamond particles have been successfully covered with magnetic Fe- and Co-containing nanoparticles by means of thermal destruction of metal-containing compounds in a hot mixture of mineral oil and detonation nanodiamond. Thus produced samples were characterized by TEM, XRD, and element analysis. Magnetic studies of the Co-containing samples have been performed.

S. P. Gubin; O. V. Popkov; G. Yu. Yurkov; V. N. Nikiforov; Yu. A. Koksharov; N. K. Eremenko

2007-01-01

204

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

205

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

SciTech Connect

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

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

1999-08-01

206

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

SciTech Connect

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

Fickel, D.; Lobo, R

2010-01-01

207

The phase relations in Earth's mid-lower mantle: constraints from in-situ XRD and quantitative chemical analysis  

NASA Astrophysics Data System (ADS)

Determining the phase relations in the system MgO-FeO-SiO2 at high pressure (P) and high temperature (T) is of fundamental importance for understanding the geochemical and geophysical properties of Earth's deep interior. The phase relations in the upper lower mantle have been investigated both in a diamond anvil cell (DAC) [1] and a multi-anvil apparatus [2]. In this study, we investigated the phase relations in (Mg0.6Fe0.4)SiO3 at elevated P-T conditions (up to 80 GPa and 3000 K) by in-situ X-ray diffraction (XRD) measurements in a DAC. Each sample was compressed to the P of interest and then heated to high T. In-situ XRD data were collected at high P-T and then the sample was quenched to preserve the high P-T chemical composition. Samples were recovered and phase chemistry was obtained by scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) analysis. Fe solubility in Pv phase increases with increasing P up to 80 GPa. (Mg0.6Fe0.4)SiO3 Pv formed at 80 GPa and its unit-cell volume is 1.8 % larger than that of Fe-free Pv (Lundin et al., 1991). Our improved knowledge of the phase relations in the mid-lower mantle and related geophysical implications will be discussed.

Zhang, L.; Meng, Y.; Prakapenka, V.; Mao, W. L.

2011-12-01

208

Characterization of K 2CO 3/Co-MoS 2 catalyst by XRD, XPS, SEM, and EDS  

NASA Astrophysics Data System (ADS)

MoS 2, Co-MoS 2 and K 2CO 3/Co-MoS 2 catalysts have been characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). XRD analysis indicates that Co-MoS 2 is a primary phase in K 2CO 3/Co-MoS 2 catalyst and the diffraction lines of Co-MoS 2 are not changed by the addition of K 2CO 3. Co 9S 8 phase is not present at Co/Mo mole ratio of 0.5 using a co-precipitation method for preparation of cobalt-molybdenum catalyst. The binding energies (BEs) of chemical species present on the surface of the catalysts are compared through the course of catalyst preparation. K 2CO 3/Co-MoS 2 catalyst has been investigated as a function of dispersion of K on the surface and exposure to a mixture of carbon monoxide and hydrogen (syngas) by scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The distribution of potassium on the surface of the K-promoted catalyst is not uniform.

Iranmahboob, Jamshid; Hill, Donald O.; Toghiani, Hossein

2001-12-01

209

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

210

Characterization of stabilized/solidified refinery oily sludge and incinerated refinery sludge with cement using XRD, SEM and EXAFS.  

PubMed

Solidification/stabilization (S/S) of refinery oily sludge and incinerated oily sludge (ash) with cement type I42.5 and II42.5 was investigated using, X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) combined with Energy Dispersive Spectroscopy (EDS) and Extended X-ray Absorption Fine Structure (EXAFS). The results showed that delayed ettringite formation (DEF) and major cement hydration reactions occurred. XRD analysis of S/S oily sludge samples revealed cement-bearing solid phases, such as portlandite, calcite, C(3)S, C(2)S and C(4)AF. SEM analysis, confirmed ettringite at solidified oily sludge samples. Solidified ash samples contained ettringite substituted by chromates. However, solid phases found in solidified ash samples with I42.5 cement showed minor variation in type and structure compared to those observed in solidified ash samples with II42.5 cement. Fe K edge EXAFS analysis revealed the presence of iron oxides in both S/S wastes. The comparison between spectra of the S/S resulting materials and the ones of their original components, showed that the first sphere Fe-O distances were longer than in the pure iron oxide thereby providing evidence that the resulting materials were not simple mixtures, but products of a reaction that modified the local environment of iron. PMID:18584430

Karamalidis, Athanasios K; Psycharis, Vasileios; Nicolis, Ioannis; Pavlidou, Eleni; Benazeth, Simone; Voudrias, Evangelos A

2008-08-01

211

High-pressure high-temperature synthesis of Mn 4Nb 2O 9. A XRD and TEM study  

NASA Astrophysics Data System (ADS)

A new high-pressure, high-temperature modification of Mn 4Nb 2O 9, has been prepared at T=1700 °C, P=9 GPa. The XRD study based on Rietveld technique suggests the structure to be a rhombohedral (R3c) modification of Mn 4Nb 2O 9, (LiNbO 3 type structure) with the chemical formula Mn(Mn 1/3Nb 2/3)O 3 and unit cell parameters a=5.34139(2), c=14.15807(7) Å. However, electron diffraction (ED) and high resolution electron microscopy (HREM) images of crystallites found in an XRD single phase sample revealed frequent disorder, but also the existence of a new monoclinic modification of Mn 4Nb 2O 9 often intergrown with the corundum related P 3¯c1-Mn 4Nb 2O 9 modification stable at ambient pressure and temperature. This new monoclinic modification has the unit cell parameters: a=9.93, b=5.34, c=13.20 Å, ?=92.9° and space group C2/c or Cc. It is closely related to the corundum lattice since its c ? axis is parallel to <2 0 2> ?R 3¯c in the rhombohedral sublattice.

Tyutyunnik, Alexander P.; Zubkov, Vladimir G.; D'yachkova, Tatjana V.; Zainulin, Yury G.; Tarakina, Nadezhda V.; Sayagués, Mar?´a. J.; Svensson, Gunnar

2002-06-01

212

A facile route to sonochemical synthesis of magnetic iron oxide (Fe 3O 4) nanoparticles  

Microsoft Academic Search

A facile sonochemical approach was applied for the large scale synthesis of iron oxide magnetic nanoparticles (NPs) using inexpensive and non-toxic metal salts as reactants. The as-prepared magnetic iron oxide NPs has been characterized by XRD, TEM, EDS, and VSM. X-ray diffraction (XRD) and EDS analysis revealed that Fe3O4 NPs have been successfully synthesized in a single reaction by this

Le Van Phong; Jong-Ryul Jeong; CheolGi Kim

2011-01-01

213

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

PubMed

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

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

1998-12-25

214

GREGÓRIO LOPES painting workshop: characterization by X-ray based techniques. Analysis by EDXRF, ?-XRD and SEM-EDS  

NASA Astrophysics Data System (ADS)

Gregório Lopes is one of the most famous Portuguese painters of the 15th–16th centuries. This work is a contribution to the study of his painting technique, specifically addressing the methodology used in the preparation of ground layers, which has never been carried out previously with this multianalytical method. For this purpose characterization of the ground layers of a selection of his paintings was carried out by micro-Energy Dispersive X-ray Fluorescence spectroscopy (?-EDXRF), micro-X-ray Diffraction (?-XRD), Scanning Electron Microscopy - Energy Dispersive Spectroscopy (SEM-EDS) and complemented by micro-Raman spectroscopy. This work presents the results obtained on two altarpieces (c.1544) produced at the same period by this Portuguese artist. Ground layers are composed mainly of calcium sulfate — anhydrite and gypsum — and other compounds such as dolomite. Reference samples were prepared to obtain diffraction pattern of different percentage of gypsum and anhydrite and compared with the results from historical samples.

Antunes, V.; Candeias, A.; Carvalho, M. L.; Oliveira, M. J.; Manso, M.; Seruya, A. I.; Coroado, J.; Dias, L.; Mirão, J.; Longelin, S.; Serrão, V.

2014-05-01

215

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

PubMed

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

Habibi, Neda

2014-10-15

216

Structural Properties of AlN Films with Oxygen Content Deposited by Reactive Magnetron Sputtering:. XRD and XPS Characterization  

NASA Astrophysics Data System (ADS)

A set of aluminium nitride (AlN) and oxidized AlN (AlNO) thin films were grown with the technique of direct current (dc) reactive magnetron sputtering. The main purpose of this investigation is to explore the influence of the oxygen on the structural properties of AlN and AlNO films. The crystalline properties and chemical identification of phases were studied by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. Electrical properties were analyzed from I-V measurements. It was found that films crystallized under the AlN würzite structure and presented a polycrystalline preferential growth along [0001] direction, perpendicular to substrate. Small amounts of secondary aluminium oxide phases were detected too. The oxide phases can induce defects, which can alter crystallinity of films.

García-Méndez, Manuel; Morales-Rodríguez, Santos; Shaji, Sadasivan; Krishnan, Bindu; Bartolo-Pérez, Pascual

217

[XRD, FTIR and XPS analysis of oxidized particles from Dongshengmiao pyrite-polymetallic sulfide deposit, inner Mongolia].  

PubMed

In the present paper, characteristics of material compositions, phase structures, surface element states, and transformation mechanism of oxidized particles from Dongshengmiao pyrite-polymetallic sulfide deposit were studied using modern analytical testing technology including XRD, FTIR and XPS. The results show that the samples consist of gypsum, calcite, quartz, muscovite, goethite, organic matter, etc. Primary ore in deep oxidation zone mainly under went such processes as oxidization, hydrolysis, dehydration and carbonation. Compared to the surface oxidation zone of arid and extremely arid regions in the northwestern China, the oxidation process and oxidizing condition of the deep oxidation zone were less complex. New mineral type was also not found, and extensively developed sulfate minerals were rare to be seen. The research results can not only be applied to mineral identification of oxidized particles from this type of ore deposit but also play an important role in ore exploration, mining, mineral processing, etc. PMID:23586262

Yuan, Xue-Ling; Cao, Jian-Jin; Xie, Fang-Yan; Yang, Xiao-Jie; Yan, Hong-Bin; Lai, Pei-Xin; Wang, Zheng-Hai; Zeng, Jian-Nian

2013-01-01

218

Nanostructuring and strengthening of LiF crystals by swift heavy ions: AFM, XRD and nanoindentation study  

NASA Astrophysics Data System (ADS)

Modifications of the structure and micromechanical properties of LiF crystals under high-fluence irradiation (1011-1013 ions cm-2) with swift C, Ti, Au and U ions of the specific energy of 11.1 MeV/u have been studied. In the case of heavy ions (U, Au), the AFM and SEM results reveal the bulk nanostructure consisting of columnar grains with nano-scale dimensions (50-100 nm). For lighter C ions the structure enriched with prismatic dislocation loops has been observed. High-resolution XRD reciprocal space maps for nano-structured LiF expose a mosaic-type structure with low-angle boundaries between grains.

Maniks, J.; Manika, I.; Zabels, R.; Grants, R.; Tamanis, E.; Schwartz, K.

2012-07-01

219

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

220

Micro-XRD Stress And Texture Study Of Inlaid Copper Lines - Influence Of ILD, Liner And Etch Stop Layer  

SciTech Connect

The influence of ILD, liner and etch stop layer on the room temperature stress state of copper line test structures was examined by micro-XRD. Test structures consisted of large arrays of parallel lines with line widths of 0.18 {mu}m and 1.8 {mu}m. All these parameters have an influence on the room temperature stress state, whereas the variation of the liner and the ILD showed the largest effects. The change from a full low-k stack to a hybrid stack, where SiO2 ILD is use for the 'via layer' only and low-k material for the 'line layer' results in completely different parameter dependencies. The relationship between copper microstructure and the resulting stress in copper lines is discussed.

Prinz, H.; Zienert, I.; Rinderknecht, J.; Geisler, H.; Zschech, E. [AMD Saxony LLC and Co. KG. MS E23-MA, Wilschdorfer Landstrasse 101, 01109 Dresden (Germany); Besser, P. [AMD Inc., P.O. Box 3453, MS36, Sunnyvale, CA 94088-3453 (United States)

2004-12-08

221

Hydrated Iron Sulfate Minerals by FT-IR, ESEM and XRD: Effects of Hydration, Metal Ions, and Oxidative State  

NASA Astrophysics Data System (ADS)

Data from the Mars Exploration Rovers (MER) and orbital remote sensing have determined that iron-bearing sulfates and iron-sulfates account for much of the mineralogical variation on Martian chemical sediments. We have begun a comprehensive study to evaluate a suite of hydrated iron sulfate minerals at different levels of oxidation or mineral phases using micro-FT-IR, ESEM and XRD. Selected minerals include jarosite, copiapite, coquimbite, halotrichite, kornelite, melanterite, rhomboclase, roemerite, rozenite, and szomolnokite. The structure and wavelength of the water bands are controlled by the immediate proximity of the water molecules to the Fe3+ and Fe2+ cores. Iron and aluminum change the fundamental vibration amplitudes and shift the energy requirement for a specific bond vibration. The original mineral spectral signature can be present even after oxidative products form on the iron sulfate surfaces and basic spectral lines can be analyzed. When mineral samples were sectioned and analysis performed on the interior mineral surfaces, the spectra showed the predominant spectral lines under both conditions with most variations occurring in peak definition. ESEM-EDAX and XRD analysis confirmed the presence of oxidative products on the mineral surfaces even when the mineral samples were stored in anoxic conditions (under mineral oil) and refrigerated in airtight containers after sampling. Spectral variability between 30 micron spots within 200x200 micron areas showed minimal compositional / spectral variability. The micro-spectroscopic approach permits the study of complex iron sulfate mineral structures (e.g. evaporite sequences, crystal formations) to determine the hydration, metal ion, and oxidative state in terrestrial analog systems and on future Mars missions, without destruction of the sample.

Mielke, R.; Blaney, D.; Nordstrom, K.; Aplers, C.; Coleman, M.

2007-12-01

222

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

223

Constraints on the Thermal History of Martian Meteorites ALH84001 and MIL03346 by Single Crystal XRD, Electron Microprobe and Mössbauer Analyses of Ortho- and Clinopyroxene  

NASA Astrophysics Data System (ADS)

Constraints on the thermal history of meteorites can be established by estimating the Fe2+-Mg order degree in their pyroxene using single-crystal XRD. We present here the data obtained on martian meteorites ALH84001 and MIL03346.

Domeneghetti, M. C.; Fioretti, A. M.; Cámara, F.; Carraro, A.; McCammon, C.; Tazzoli, V.

2007-07-01

224

XRD Measurement of Mean Thickness, Thickness Distribution and Strain for Illite and Illite-Smectite Crystallites by the Bertaut-Warren-Averbach Technique  

Microsoft Academic Search

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

V. A. Drits; D. D. EBERL; J. SRODOI

1998-01-01

225

Structure and magnetic properties of magnetically isotropic and anisotropic Nd-Fe-B permanent magnets prepared by spark plasma sintering technology  

NASA Astrophysics Data System (ADS)

Spark plasma sintering technique had been applied to prepare bulk isotropic and anisotropic nanostructured Nd-Fe-B permanent magnets via hot pressing and subsequent hot deformation process. Influences of processing conditions and deformation height reduction on the structure and magnetic properties of the magnets were investigated. For the hot deformed magnet with 80% height reduction, XRD patterns of the anisotropic magnets show dominant (00l) diffraction peaks indicating evident c-axis crystallographic alignment in the magnet. Under the optimal processing conditions, the anisotropic magnet with 80% height reduction exhibits excellent magnetic properties as remanence (Br) of 1.492 T, coercive force (Hci) of 1004 kA/m, and the maximum energy product [(BH)max] of 400 kJ/m3, which are among the highest reported magnetic properties of nanostructured Nd-Fe-B permanent magnets.

Liu, W. Q.; Cui, Z. Z.; Yi, X. F.; Yue, M.; Jiang, Y. B.; Zhang, D. T.; Zhang, J. X.; Liu, X. B.

2010-05-01

226

Chemical diffusion: Another factor affecting the magnetoresistance ratio in Ta/CoFeB/MgO/CoFeB/Ta magnetic tunnel junction  

NASA Astrophysics Data System (ADS)

This letter investigates the microstructure and mean inner potential (MIP) profile of Ta/CoFeB/MgO/CoFeB/Ta magnetic tunnel junctions (MTJs) by high resolution transmission electron microscopy (HRTEM) and electron holography, respectively. The inconspicuous crystallization of MgO barrier is confirmed by HRTEM in the post-annealed sample at 250 °C. An obvious MIP difference is displayed in the Ta layers between the top and bottom of the MTJ, and elemental content difference of them is confirmed by energy dispersive spectroscopy. These results imply that the chemical diffusion can also give rise to a lower tunnel magnetoresistance ratio besides the inconspicuous crystallization of MgO barrier.

Yang, Y.; Wang, W. X.; Yao, Y.; Liu, H. F.; Naganuma, H.; Sakul, T. S.; Han, X. F.; Yu, R. C.

2012-07-01

227

Magnetism and Magnetic Properties  

NSDL National Science Digital Library

Students will identify properties of magnetism and begin to develop understanding of their practical applications. Students will also begin to develop understanding of the essential nature of Earth's magnetic fields.

Schneck, Roberta

2011-10-13

228

[TG-FTIR and XRD spectroscopic analysis for the preparation of nitrogen-doped carbon supported cobalt electrocatalysts].  

PubMed

Nitrogen-doped carbon supported cobalt electrocatalysts for the reduction of oxygen were prepared from the high nitrogen content prepolymer of melamine formaldehyde resin and cobalt acetate. The preparation and structure of the electrocatalysts were investigated by TG-FTIR and XRD spectroscopic analysis methods. The electrochemical reduction of oxygen was studied at the nitrogen-doped carbon supported cobalt by using the rotating disk electrode method. The results indicated that the catalyst structure changed with the carbonization temperature under the protection of the inert gases. Some organic groups were decomposed into CO, CO2, HCHO, NH3 and NO2, which were taken away by the protecting gas. The electrocatalysts exhibited face-centered cubic structure. The RDE results showed that good electrocatalytic activity for oxygen reduction at these electrocatalysts was found under the experimental condition. The onset potential for oxygen reduction (E(onset)) was 0.5 V (vs. SCE). The catalyst prepared under 700 C was found to have the highest activity. PMID:22715797

Yang, Wei; Chen, Sheng-zhou; Zou, Han-bo; Lin, Wei-ming

2012-04-01

229

TEM, XRD and AFM study of poly( o-ethoxyaniline) films: new evidence for the formation of conducting islands  

NASA Astrophysics Data System (ADS)

The existence of conducting islands in polyaniline films has long been proposed in the literature, which would be consistent with conducting mechanisms based on hopping. Obtaining direct evidence of conducting islands, however, is not straightforward. In this paper, conducting islands were visualized in poly( o-ethoxyaniline) (POEA) films prepared at low pH, using Transmission Electron Microscopy (TEM) and atomic force spectroscopy (AFS). The size of the islands varied between 67 and 470 Å for a pH=3.0, with a larger average being obtained with AFS, probably due to the finite size effect of the atomic force microscopy tip. In AFS, the conducting islands were denoted by regions with repulsive forces due to the double-layer forces. On the basis of X-ray diffraction (XRD) patterns for POEA in the powder form, we infer that the conducting islands are crystalline, and therefore a POEA film is believed to consist of conducting islands dispersed in an insulating, amorphous matrix. From conductivity measurements we inferred the charge transport to be governed by a typical quasi-one dimensional variable range hopping (VRH) mechanism.

Leite, Fabio L.; Alves, William F.; Mir, Mirta; Mascarenhas, Yvonne P.; Herrmann, Paulo S. P.; Mattoso, Luiz H. C.; Oliveira, Osvaldo N.

2008-11-01

230

XRD, XPS, optical, and Raman investigations of structural changes of nanoCo-doped ZnO  

NASA Astrophysics Data System (ADS)

The mixed oxides Zn1-xCoxO (ZCO) (0.0 ? x ? 3.0) were prepared as nanopolycrystalline powders and thin films by a simple sol-gel process and dip coating method. Structural and microstructural analysis was carried out applying X-ray diffraction (XRD) and Rietveld method. Analysis showed that for x < 0.12, Co2+ replaces Zn2+ substitutionally yielding ZCO single phase, while for x ? 0.15 two phases are identified; ZCO and Co3O4. Replacing Zn+2 by Co+2 affects the lattice parameters in opposite ways, the parameter c decreases while a increases with an overall decrease in the ratio c/a of the wurtzite ZCO, which deviates the lattice gradually from the hexagonal structure as Co+2 increases. The IR analysis shows red shift entirely dependent on Co concentration. With increased concentration of cobalt the E2high Raman mode exhibits a redshift attributed to the phonon softening caused by the ab-plane lattice expansion, while the E2low mode shows a blueshift due to the reduced mass effect caused by cation replacement.

Heiba, Z. K.; Arda, L.

2012-08-01

231

Surface mediated Ag-Hg alloy formation under ambient and vacuum conditions—AFM and XRD investigations  

NASA Astrophysics Data System (ADS)

Thin Ag films deposited under UHV conditions on a glass support were exposed to Hg vapor at 298 K under two different conditions: vacuum, and ambient atmosphere. The influence of the amalgamation process on film topography was studied by the atomic force microscopy (AFM) method, while the composition of the amalgams was determined by means of X-ray diffraction (XRD). The obtained results indicated the different mechanism of Ag 2Hg 3 alloy formation depending on whether the amalgam is formed in a vacuum or under ambient atmosphere. This is discussed as a consequence of the influence of oxygen and different kinetics of the amalgamation process performed under both conditions. Heating of amalgam leads to gradual reconstruction of the alloy (370 K) and finally its decomposition (500 K), leaving strongly modified, discontinuous silver film. The ultimate nanostructure of the film depends on the transport mechanism of the silver nanounits during the amalgamation process. Therefore, Ag-Hg alloy formation and decomposition seems to be a practical and promising method for the preparation of discontinuous thin silver films of significant thickness and mesoscopic structure.

Nowakowski, Robert; Pielaszek, Jerzy; Du?, Ryszard

232

Catalytic partial oxidation of methane to synthesis gas over Ni-based catalysts. 2: Transient, FTIR, and XRD measurements  

SciTech Connect

Ni/La{sub 2}O{sub 3} and Ni/Al{sub 2}O{sub 3} catalysts were studied under conditions of partial oxidation of methane to synthesis gas. Temperature-programmed oxidation and hydrogenation experiments have shown that carbon accumulation over Ni/La{sub 2}O{sub 3} during CPO remains essentially constant after 2 h time on-stream, while over Ni/Al{sub 2}O{sub 3} it increases during the initial several hours. FTIR spectroscopy of surface species formed over the Ni/La{sub 2}O{sub 3} catalyst under reaction conditions indicates that the carbonate species formed over the support do not decompose under He and O{sub 2} treatment at 600 C. XRD spectra obtained following high ({approximately}90%) or low (<10%) methane conversions show that Ni, La{sub 2}O{sub 3}, La{sub 2}O{sub 2}CO{sub 3}, NiO, and Ni{sub 3}C phases are present in the case of high methane and complete oxygen conversions, while nickel oxide, nickel carbide and, to a small extent, La{sub 2}O{sub 2}CO{sub 3} phases are present in the case of low CH{sub 4} and incomplete oxygen conversions.

Tsipouriari, V.A.; Verykios, X.E. [Univ. of Patras (Greece). Dept. of Chemical Engineering] [Univ. of Patras (Greece). Dept. of Chemical Engineering

1998-10-01

233

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

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

234

Single crystal XRD structure and theoretical analysis of the chiral Au30S(S-t-Bu)18 cluster.  

PubMed

Au30S(S-t-Bu)18 cluster, related closely to the recently isolated "green gold" compound Au30(S-t-Bu)18, has been structurally solved via single-crystal XRD and analyzed by density functional theory calculations. The molecular protecting layer shows a combination of monomeric (RS-Au-SR) and trimeric (RS-Au-SR-Au-SR-Au-SR) gold-thiolate units, bridging thiolates, and a single sulfur (sulfide) in a novel ?3-coordinating position. The chiral gold core has a geometrical component that is identical to the core of the recently reported Au28(SPh-t-Bu)20. Both enantiomers of Au30S(S-t-Bu)18 are found in the crystal unit cell. The calculated CD spectrum bears a close resemblance to that of Au28(SPh-t-Bu)20. This is the first time when two structurally characterized thiol-stabilized gold clusters are found to have such closely related metal core structures and the results may increase understanding of the formation of gold clusters when stabilized by bulky thiolates. PMID:24605935

Crasto, David; Malola, Sami; Brosofsky, Grace; Dass, Amala; Häkkinen, Hannu

2014-04-01

235

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

236

Influence of a silica interlayer on the structural and magnetic properties of sol-gel TiO?-coated magnetic nanoparticles.  

PubMed

Superparamagnetic iron oxide nanoparticles coated with titanium dioxide have been synthesized, growing the titanium dioxide directly either on the magnetic nuclei or on magnetic nanoparticles previously coated with a semihydrophobic silica layer. Both coatings have been obtained by sol-gel. Since it is well-known that the existence of the intermediate silica layer influences the physicochemical properties of the material, a detailed characterization of both types of coatings has been carried out. The morphology, structure, and composition of the synthesized nanomatrices have been locally analyzed with subangstrom spatial resolution, by means of aberration corrected transmission electron microscopy (HRTEM and STEM-HAADF). Besides magnetization measurements, proton relaxivity experiments have been also performed on water suspensions of the as-synthesized nanoparticles to investigate the role of the silica interlayer in the relaxometric properties. The silica interlayer leads to nanoparticles with much higher water stability and to higher relaxivity of the suspensions. PMID:24694292

De Matteis, Laura; Fernández-Pacheco, Rodrigo; Custardoy, Laura; García-Martín, María L; de la Fuente, Jesús M; Marquina, Clara; Ibarra, M Ricardo

2014-05-13

237

Influence of surface modification of SrFe 12O 19 particles with oleic acid on magnetic microsphere preparation  

Microsoft Academic Search

Oleic acid was used as surface modification agent to improve the hydrophobicity of magnetic strontium hexaferrite particles. The structure and properties of treated magnetic particles were characterized by scanning electronic microscopy (SEM), Fourier transform infrared spectra (FTIR), powder X-ray diffraction (XRD) and magnetic property measurement system (MPMS). The results show that oleic acid is chemically enwrapped on the surface of

Sifang Kong; Peipei Zhang; Xiufang Wen; Pihui Pi; Jiang Cheng; Zhuoru Yang; Jing Hai

2008-01-01

238

New two in one magnetic fluorescent nanocomposites  

NASA Astrophysics Data System (ADS)

Magnetite nanoparticles have been coated by a porphyrin derivative to produce new magnetic materials with fluorescent properties. The magnetic nanoparticles were prepared using two different methods, one based on sol-gel techniques and ultrasonic processing, and the other via a controlled chemical co-precipitation. Different types of porphyrin functionalised magnetic nanoparticles have been prepared and have been characterised by electron microscopy (TEM and SEM), XRD, FTIR, Raman, UV-vis, and fluorescence spectroscopy. Microscopy results showed the formation of core-shell nanostructures, with IR and photoluminescence spectroscopy results confirming the presence of porphyrin in the shell.

Corr, Serena A.; Gun'ko, Yurii K.; Byrne, Stephen J.; Douvalis, Alexios P.; Venkatesan, Munuswamy; Gunning, Robert D.

2005-06-01

239

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

NASA Astrophysics Data System (ADS)

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

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

2009-05-01

240

Aragonite to Calcite Transformation Study by XRD and Esr Studies of Mn2+ in Freshwater Snail Shells:. P. Canaliculata Lamarck  

NASA Astrophysics Data System (ADS)

Electron spin resonance spectroscopy (ESR) was used to study the Mn2+ ions in snails of P. canaliculata lamarck (PCL). All these shells are abundant in Thailand. Fractions of aragonite and calcite phase in the shells have been approximately determined by ESR. The PCL shell was ground into fine powders and then four samples were separately annealed for 2 h in air at 400°C, 450°C, 500°C and 600°C, respectively. The phase transition from aragonite to calcite was monitored by X-ray diffractometer (XRD) and electron spin resonance spectrometer (ESR). Our results show that unheated PCL sample is mainly made of aragonite with only a small fraction of calcite. Annealing of the PCL powder sample at the temperature more than 450°C has resulted in the irreversible phase transformation from aragonite to calcite. The analysis of their ESR spectra has shown that Mn2+ ions partially substituted Ca2+ in the lattices. Finally, the spin Hamiltonian parameters for Mn2+ distributed in both aragonite and calcite were evaluated. Our detailed ESR spectral analyses of PCL show that Mn2+ ions enter Ca2+ sites during a biomineralization process. Typical simulated ESR parameters of PCL-500 of Mn2+ at a uniaxial site of calcite are gx=gy=2.078(1), gz=1.999(1), Ax=Ay=87.0 G, Az=89.00 G and D=115 G, respectively. It is thus possible to gain some insight of manganese incorporation into the fresh water shells during the biomineralization process.

Udomkan, N.; Limsuwan, P.; Chaimanee, Y.

241

Transformation of meta-stable calcium silicate hydrates to tobermorite: reaction kinetics and molecular structure from XRD and NMR spectroscopy.  

PubMed

Understanding the integrity of well-bore systems that are lined with Portland-based cements is critical to the successful storage of sequestered CO2 in gas and oil reservoirs. As a first step, we investigate reaction rates and mechanistic pathways for cement mineral growth in the absence of CO2 by coupling water chemistry with XRD and NMR spectroscopic data. We find that semi-crystalline calcium (alumino-)silicate hydrate (Al-CSH) forms as a precursor solid to the cement mineral tobermorite. Rate constants for tobermorite growth were found to be k = 0.6 (+/- 0.1) x 10(-5) s(-1) for a solution:solid of 10:1 and 1.6 (+/- 0.8) x 10(-4) s(-1) for a solution:solid of 5:1 (batch mode; T = 150 degrees C). This data indicates that reaction rates for tobermorite growth are faster when the solution volume is reduced by half, suggesting that rates are dependent on solution saturation and that the Gibbs free energy is the reaction driver. However, calculated solution saturation indexes for Al-CSH and tobermorite differ by less than one log unit, which is within the measured uncertainty. Based on this data, we consider both heterogeneous nucleation as the thermodynamic driver and internal restructuring as possible mechanistic pathways for growth. We also use NMR spectroscopy to characterize the site symmetry and bonding environment of Al and Si in a reacted tobermorite sample. We find two [4]Al coordination structures at delta iso = 59.9 ppm and 66.3 ppm with quadrupolar product parameters (PQ) of 0.21 MHz and 0.10 MHz (+/- 0.08) from 27Al 3Q-MAS NMR and speculate on the Al occupancy of framework sites by probing the protonation environment of Al metal centers using 27Al{1H}CP-MAS NMR. PMID:19144195

Houston, Jacqueline R; Maxwell, Robert S; Carroll, Susan A

2009-01-01

242

In-situ XRD study of the olivine - ringwoodite transformation kinetics: application for effects of water on its growth kinetics  

NASA Astrophysics Data System (ADS)

Dependence of water on the growth kinetics in San Carlos olivine phase transformation to ringwoodite was investigated with time-reserved X-ray diffraction method on BL04B1 station at SPring 8. The starting material is San Carlos olivine powder. Water is added by a mixture of Mg(OH)2 and SiO2. Single crystalline diamond or Ag-Pd is used as the sample capsule to prevent the escape of water. Pressure is generated by the double stage method in the SPEED 1500 system and measured by the gold pressure maker. After the annealing of the sample in the olivine stability field, we observed the olivine-ringwoodite transformation kinetics by time-reserved X-ray diffraction measurements with energy dispersive method using a solid-state detector. Kinetic data of the olivine phase transformation to ringwoodite, at about 16-20 GPa, 680-1050 C, and 500-2000 wt. ppm. H2O, were obtained. In previous kinetic studies, in-situ XRD experiments have been limited to the olivine-wadsleyite transformation. However, the kinetic data on the olivine-ringwoodite transformation is also indispensable to discuss the presence of the metastable olivine seismologically detected in some slabs. The kinetic data newly obtained here, combined with the previous published data, are used to study the effect of water on the olivine transformation to ringwoodite.. We will discuss the difference of the olivine transformation to ringwoodite and to wadsleyite, and the extent of metastable olivine in subduction zone under complicated water environment.

Ning, J.; Wang, S.; Kubo, T.; Higo, Y.; Funakoshi, K.

2012-12-01

243

Following the Formation of Active Co(III) Sites in Cobalt Substituted Aluminophosphates Catalysts by In-Situ Combined UV-VIS/XAFS/XRD Technique  

NASA Astrophysics Data System (ADS)

Cobalt substituted aluminophosphates, CoAlPO-34 (Chabazite structure) and DAF-8 (Phillipsite structure) were investigated by in situ combined XRD/EXAFS/UV-VIS technique. In-situ combined XRD, Co K-edge EXAFS and UV-Vis measurements carried out during the calcination process reveal that CoAlPO-34 containing 10 wt percent cobalt is stable and the cobalt ions are converted from Co(II) in the as synthesised form to Co(III) DAF-8 containing about 25 percent cobalt is not stable and does not show change in oxidation state.

Sankar, Gopinathan; Fiddy, Steven; Beale, Andrew M.; Harvey, Ian; Hayama, Shusaku; Bushnell-Wye, Graham

2007-02-01

244

Following the Formation of Active Co(III) Sites in Cobalt Substituted Aluminophosphates Catalysts by In-Situ Combined UV-VIS/XAFS/XRD Technique  

SciTech Connect

Cobalt substituted aluminophosphates, CoAlPO-34 (Chabazite structure) and DAF-8 (Phillipsite structure) were investigated by in situ combined XRD/EXAFS/UV-VIS technique. In-situ combined XRD, Co K-edge EXAFS and UV-Vis measurements carried out during the calcination process reveal that CoAlPO-34 containing 10 wt percent cobalt is stable and the cobalt ions are converted from Co(II) in the as synthesised form to Co(III); DAF-8 containing about 25 percent cobalt is not stable and does not show change in oxidation state.

Sankar, Gopinathan [Davy Faraday Research Laboratory, The Royal Institution of GB, 21 Albemarle Street, London W1S 4BS (United Kingdom); Daresbury Laboratory, Daresbury, Warrington, Cheshire WA4 4AD (United Kingdom); Fiddy, Steven; Harvey, Ian; Hayama, Shusaku; Bushnell-Wye, Graham [Daresbury Laboratory, Daresbury, Warrington, Cheshire WA4 4AD (United Kingdom); Beale, Andrew M. [Department of Inorganic Chemistry and Catalysis, Debye-Institute, Utrecht University, Sorbonnelaan 16, 3508 TC Utrecht (Netherlands)

2007-02-02

245

Following the Formation of Active Co(III) Sites in Cobalt Substituted Aluminophosphates Catalysts by In-Situ Combined UV-VIS\\/XAFS\\/XRD Technique  

Microsoft Academic Search

Cobalt substituted aluminophosphates, CoAlPO-34 (Chabazite structure) and DAF-8 (Phillipsite structure) were investigated by in situ combined XRD\\/EXAFS\\/UV-VIS technique. In-situ combined XRD, Co K-edge EXAFS and UV-Vis measurements carried out during the calcination process reveal that CoAlPO-34 containing 10 wt percent cobalt is stable and the cobalt ions are converted from Co(II) in the as synthesised form to Co(III) DAF-8 containing

Gopinathan Sankar; Steven Fiddy; Andrew M. Beale; Ian Harvey; Shusaku Hayama; Graham Bushnell-Wye

2007-01-01

246

Interface charge transfer in polypyrrole coated perovskite manganite magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

247

Temperature dependence of the cation distribution in nickel aluminate (NiAl2O4) spinel: a powder XRD study  

NASA Astrophysics Data System (ADS)

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 a precision of ± 0.004 (one standard deviation), and a comparison of different methods of synthesis, X-ray diffraction and refinement techniques, suggests a probable accuracy of better than 0.01. The results are supported by some preliminary single crystal refinements on flux-grown samples. Below 800° C the rate of cation ordering becomes very slow, and, despite reaching an apparently steady state, it is doubtful if our samples attained complete internal equilibrium. Above 1250° C the cation redistribution becomes so fast that the quenching method becomes unreliable. Between 800 and 1250° C inclusive, the degree of inversion changes smoothly from 0.87 at 800° C to 0.79 at 1250° C, and is accompanied by linear changes in u, the oxygen parameter, from 0.2555 to 0.2563 (±0.0002), and a0, the lattice parameter, from 8.0462 to 8.0522 Å (±0.0002 Å). If no non-configurational entropy of disordering is assumed, the change of x with temperature can be described by a non-linear enthalpy of disordering model (O'Neill and Navrotsky 1983, 1984) with ?Ni-Al=17.5 ±2.3, ?=-18.4± 1.4 kJ/g-atom. The ? term thus agrees with the -20 kJ/g-atom suggested for all 2 3 spinels by O'Neill and Navrotsky (1984). However, if the expected electronic entropy of Ni2+ in tetrahedral co-ordination is included (9.13 J/K g-atom), a very different best fit value of ?=+8.3 kJ/mol is obtained. The present data, despite their precision, cannot be used to distinguish between these alternative models.

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

1991-12-01

248

Comprehensive review of the XRD data of the primary and secondary phases present in the BSCCO superconductor system: Part 1, Ca-Sr-Cu oxides.  

National Technical Information Service (NTIS)

X-ray powder patterns for the phases in the CaO-SrO-CuO ternary system, along with the corresponding crystal structures, were obtained from the literature and from the Powder Diffraction File (PDF). Available X-ray diffraction (XRD) patterns were compared...

B. J. Reardon C. R. Hubbard

1992-01-01

249

Comprehensive review of the XRD data of the primary and secondary phases present in the BSCCO superconductor system. Part 2, Ca-Sr-Pb oxides.  

National Technical Information Service (NTIS)

X-ray powder patterns for the phases in the CaO-SrO-PbO ternary system, along with the corresponding crystal structures, were obtained from the literature and from the Powder Diffraction File (PDF). Available X-ray diffraction (XRD) patterns were compared...

B. J. Reardon C. R. Hubbard

1992-01-01

250

High-pressure studies for minerals by novel developed 3D-XRD technique using high energy synchrotron x-ray (Invited)  

Microsoft Academic Search

The studies of polymorphism for key minerals in high-pressure domain will undoubtedly broaden our knowledge about the deep interior of the Earth, and have a significant impact on the existing theories about the state, structure, formation, and evolution of the Earth. The high energy synchrotron x-ray diffraction (XRD) and diamond anvil cell (DAC) techniques were widely used to study these

H. Liu; L. Wang; J. Zhao; Z. Yu

2009-01-01

251

XRD measurement of mean crystallite thickness of illite and illite/smectite: Reappraisal of the Kubler index and the Scherrer equation  

USGS Publications Warehouse

The standard form of the Scherrer equation, which has been used to calculate the mean thickness of the coherent scattering domain (CSD) of illite crystals from X-ray diffraction (XRD) full width data at half maximum (FWHM) intensity, employs a constant, Ksh, of 0.89. Use of this constant is unjustified, even if swelling has no effect on peak broadening, because this constant is valid only if all CSDs have a single thickness. For different thickness distributions, the Scherrer "constant" has very different values. Analysis of fundamental particle thickness data (transmission electron microscopy, TEM) for samples of authigenic illite and illite/smectite from diagenetically altered pyroclastics and filamentous illites from sandstones reveals a unique family of lognormal thickness distributions for these clays. Experimental relations between the distributions' lognormal parameters and mean thicknesses are established. These relations then are used to calculate the mean thickness of CSDs for illitic samples from XRD FWHM, or from integral XRD peak widths (integrated intensity/maximum intensity). For mixed-layer illite/smectite, the measured thickness of the CSD corresponds to the mean thickness of the mixed-layer crystal. Using this measurement, the mean thickness of the fundamental particles that compose the mixed-layer crystals can be calculated after XRD determination of precent smectitic interlayers. The effect of mixed layering (swelling) on XRD peak width for these samples is eliminated by using the 003 reflection for glycolated samples, and the 001, 002 or 003 reflection for dehydrated, K-saturated samples. If this technique is applied to the 001 reflection of air-dried samples (Kubler index measurement), mean CSD thicknesses are underestimated due to the mixed-layering effect. The technique was calibrated using NEWMOD ??-simulated XRD profiles of illite, and then tested on well-characterized illite and illite/smectite smaples. The XRD measurements are in good agreement with estimates of the mean thickness of fundamental particles obtained both TEM measurements and from fixed cations content, up to a mean value of 20 layers. Correction for instrumental broadening under the conditions employed here is unnecessary for this range of thicknesses.

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

1997-01-01

252

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

253

Excellent magnetic properties of fullerene encapsulated ferromagnetic nanoclusters  

NASA Astrophysics Data System (ADS)

Ferromagnetic nanoclusters are very useful for a magnetic recording. However, application of ferromagnetic nanoclusters is limited due to air-oxidation. One way to solve air-oxidation is to encapsulate ferromagnetic nanoclusters with inert materials such as carbon when they are produced. This allows us to keep excellent magnetic properties for a long time. In this work, we report a very simple synthetic method of fullerene (i.e., onions and nanotubes) encapsulated ferromagnetic nickel and cobalt nanoclusters by thermally decomposing metallocene vapors with a resistive heater. Protection from air-oxidation was tested by annealing encapsulated ferromagnetic nanoclusters in air up to ˜180°C for half a day and then, recording XRD patterns. No oxide peaks were observed in the XRD patterns, indicating that oxidation protection via fullerene encapsulation is very good. Magnetic property measurement showed that both fullerene encapsulated nickel and cobalt nanoclusters possessed excellent magnetic properties.

Lee, G. H.; Huh, S. H.; Jeong, J. W.; Ri, H.-C.

2002-05-01

254

Magnetic Polymer Nanocomposites with Tunable Microwave Properties  

Microsoft Academic Search

Due to the multifunctionality, polymer nanocomposites (PNCs) have potential applications for electromagnetic interference shielding, tunable electromagnetic devices and flexible electronics. We report on synthesis, magnetic and RF characterization of polymer films loaded with varying concentrations of Fe3O4 and CoFe2O4 nanoparticles. The nanoparticles (5 ± 1 nm) were synthesized by chemical co-precipitation. Structural properties were characterized by XRD and TEM. Nanoparticles

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

2010-01-01

255

Characterization of magnetic nanoparticles synthesized by sonomechanical method  

Microsoft Academic Search

We have synthesized magnetic nanoparticles using the newly developed sonomechanical method with the FeSO4'7H2O and characterized crystallographic structural changes, surface morphology, chemical bonding states and magnetic properties. The crystallographic structure of the nanoparticles was characterized with high resolution X-ray powder diffraction (XRD) analysis. The surface morphology of the nanoparticles was observed by scanning electron microscopy. The chemical bonding states of

Ki-Chul Kim; Eung-Kwon Kim; Young-Sung Kim

2006-01-01

256

Defect-induced magnetism: Test of dilute magnetism in Fe-doped hexagonal BaTiO3 single crystals  

NASA Astrophysics Data System (ADS)

Single crystalline Fe-doped hexagonal BaTiO3 samples with varying oxygen content are created by specifically intended post-growth annealing treatments, in order to check the influence of defects on the unusual high temperature ferromagnetism observed in this system. The various defects have been shown to play a crucial role in dilute magnetic systems and therefore, it is important to carry out this check for the Fe-doped BaTiO3 system also, in which unusual ferromagnetism was reported even in its bulk single crystalline form. The x-ray diffraction and dielectric studies carried out here have confirmed that the Fe doping of Ti is intrinsic, while the high resolution transmission electron microscopy (HRTEM) and x-ray photoemission spectroscopy (XPS) studies proved the absence of unwanted magnetic metal clusters in the sample. The transport studies show that the oxygen concentrations could be varied substantially by the thermal treatments. Finally, magnetization measurements on the samples demonstrated that ferromagnetism is stronger in samples with higher oxygen deficiency, which could interestingly be retreated under high oxygen atmosphere and reversibly be taken back to a lower magnetic state. The vacancy-induced ferromagnetism is further confirmed by EPR measurements, which is consistent with earlier studies and, consequently, put the doped BaTiO3 in the list of true dilute magnetic oxide (DMO) systems.

Chakraborty, Tanushree; Ray, Sugata; Itoh, Mitsuru

2011-04-01

257

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

258

Hard magnets based on layered cobalt hydroxide: The importance of dipolar interaction for long-range magnetic ordering  

Microsoft Academic Search

The synthesis of 4 cobalt hydroxides, the characterization by electron microscopy, XRD, TGA, IR, UV-vis, and XANES, and their magnetic properties are reported. They belong to a family of layered compounds having a triangular magnetic lattice. The basal spacing is 22.8, 16.2, 25.0, and 11.5 â« for the carboxylate, dicarboxylate, sulfate, and cyanide, respectively. From the powder X-ray and crystal

Mohamedally Kurmoo

1999-01-01

259

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

260

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

261

Instrumental Characterization Of Coir PITH By XRD, FTIR and SEM After Radium Adsorption From Aqueous Solution Under The Presence Of Humic Acids  

NASA Astrophysics Data System (ADS)

Adsorption interactions of radium (Ra) ions onto coir pith (CP) under the presence of humic acid (HA) in the aqueous solution were investigated using X-ray diffraction (XRD), Fourier Transform Infrared Spectrophotometer (FTIR) and Scanning Electron Microscopy (SEM) techniques. XRD, IR and SEM characterization of the CP has revealed differences in the native CP and Ra ions loaded CP under the presence of HA in the aqueous solution. The X-Ray patterns showed that crystalline structure of the loaded CP exhibited a decrease in crystalline structure at around 49°-51° compared with unloaded CP. Characterization by IR revealed that participation of some surface functional groups during the Ra adsorption. SEM images for the morphological studies showed that there were slightly changes of the CP surfaces after the adsorption process.

Laili, Zalina; Omar, Muhamat; Yasir, Muhamad Samudi; Ibrahim, Mohd Zaidi; Yahaya, Mohd Yusri; Murshidi, Julie Andrianny

2010-01-01

262

Measurement of 2-5 keV x-ray emission from laser-target interactions by using fluor-MCP and CsI-XRD detectors  

SciTech Connect

For inertial confinement fusion plasma diagnostics, x-ray diode (XRD) detectors using conventional cathodes are not sensitive enough to measure x-rays above approx. 1.5 keV. However, for laser driver fusion targets, x-rays in the range of 2 to 5 keV are important because of their mobility in the target. We have successfully used fluor-microchannel plate (MCP) detectors to obtain absolute x-ray measurements in the 2 to 5 keV range. Recent data obtained from experiments on the Shiva laser system are presented. In addition, designs for a variety of channels in the range using fluor-MCP and CsI-XRD's above 1.5 keV will be discussed.

Lee, P.H.Y.; Tirsell, K.G.; Leipelt, G.R.; Laird, W.B.

1981-09-29

263

The combined study of Dy2O3-HfO2 nanocrystallites formation by means of EXAFS, PDF, XRD and SAXS  

NASA Astrophysics Data System (ADS)

The process of double oxide Dy2O3-HfO2 nanocrystallites formation upon annealing to 1600°C was investigated with the combination off few X-ray and synchrotron methods. XRD and PDF show the mean crystal structure to be fluorite typical for the compounds of Ln2O3-MeO2 type. The ordering of structure and the growth of nanocrystallites upon annealing was estimated independently from XRD patterns, PDF functions and SAXS scattering curves. Neither transition to pyrochlore phase, nor signs of recently shown in related Gd2O3-HfO2 compounds pyrochlore-type superstructure is observed. However, EXAFS and the short range order of PDF clearly indicate the discrepancy between Dy and Hf local environment. Such a disorder of local crystal structure cannot be described by the fluorite model.

Yaroslavtsev, A. A.; Menushenkov, A. P.; Leshchev, D. S.; Bednarcik, J.; Chernikov, R. V.; Zubavichus, Y. V.; Popov, V. V.; Petrunin, V. F.; Korovin, S. A.

2013-03-01

264

In situ characterization of iron phosphate and bismuth molybdate catalysts prepared by hydrothermal methods: An EDXRD and combined XRD/XAS study  

NASA Astrophysics Data System (ADS)

Iron phosphates and bismuth molybdate catalysts have been successfully prepared employing hydrothermal methods. In situ energy dispersive X-ray diffraction (EDXRD) and combined X-ray diffraction/X-ray absorption spectroscopy (XRD/XAS) studies reveal that these solid-state materials are formed from the amorphous precursor gel without the formation of any intermediate phases. While the time-resolved EDXRD measurements allowed us to determine the kinetics of phase formation, the combined XRD/XAS shows that there are local structural modifications taking place during the production of the crystalline active phases. More importantly the materials prepared by this hydrothermal method possess a much higher surface area as compared to the ones prepared by conventional methods.

Beale, Andrew M.; Sankar, Gopinathan

2003-01-01

265

Combining µXANES and µXRD mapping to analyse the heterogeneity in calcium carbonate granules excreted by the earthworm Lumbricus terrestris.  

PubMed

The use of fluorescence full spectral micro-X-ray absorption near-edge structure (µXANES) mapping is becoming more widespread in the hard energy regime. This experimental method using the Ca K-edge combined with micro-X-ray diffraction (µXRD) mapping of the same sample has been enabled on beamline I18 at Diamond Light Source. This combined approach has been used to probe both long- and short-range order in calcium carbonate granules produced by the earthworm Lumbricus terrestris. In granules produced by earthworms cultured in a control artificial soil, calcite and vaterite are observed in the granules. However, granules produced by earthworms cultivated in the same artificial soil amended with 500?p.p.m. Mg also contain an aragonite. The two techniques, µXRD and µXANES, probe different sample volumes but there is good agreement in the phase maps produced. PMID:24365942

Brinza, Loredana; Schofield, Paul F; Hodson, Mark E; Weller, Sophie; Ignatyev, Konstantin; Geraki, Kalotina; Quinn, Paul D; Mosselmans, J Frederick W

2014-01-01

266

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

SciTech Connect

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

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

2010-07-07

267

Studies on the intercalation of naproxen into layered double hydroxide and its thermal decomposition by in situ FT-IR and in situ HT-XRD  

NASA Astrophysics Data System (ADS)

Layered double hydroxides, novel anionic clay, meet the first requirement as inorganic matrices for encapsulating functional drugs or biomolecules with negative charge in aqueous media. In this study, naproxen has been intercalated into Mg-Al layered double hydroxide by the methods of ion exchange. The structure and composition of the intercalated material have been studied by X-ray diffraction (XRD), UV-vis spectroscopy and inductively coupled plasma emission spectroscopy. A schematic model has been proposed. Furthermore, in situ Fourier transform infrared spectroscopy, in situ high-temperature XRD, and thermogravimetry (TG) have been used to characterize the thermal decomposition of the hybrid material. It has been found that the thermal stability of the intercalated naproxen is significantly enhanced compared with the pure form before intercalation, which suggests that this drug-inorganic layered material may have prospective application as the basis of a novel drug delivery system.

Wei, Min; Shi, Shuxian; Wang, Ji; Li, Yong; Duan, Xue

2004-07-01

268

S 1-state Mn 4Ca complex of Photosystem II exists in equilibrium between the two most-stable isomeric substates: XRD and EXAFS evidence  

Microsoft Academic Search

Photosynthetic water oxidation reaction driven by Sun and catalyzed by a unique Mn4Ca cluster in Photosystem II (PSII) is known to take place in an oxygen evolving complex (OEC) that cycles five serial redox states, named “Kok’s Si-states” (i=0–4). Recently, the atomic crystal structure of PSII from Thermosynechococcus vulcanus was resolved by 1.9Å-resolution XRD data [55]. Interestingly, it revealed an

Masami Kusunoki

2011-01-01

269

Characterization of the Nickel Cobaltite, NiCo 2O 4, Prepared by Several Methods: An XRD, XANES, EXAFS, and XPS Study  

Microsoft Academic Search

The bulk structural properties of the nickel cobaltite, NiCo2O4, prepared by the thermal decomposition of carbonates, sol–gel methods, and the decomposition of hydroxides, have been examined by X-ray powder diffraction (XRD) and X-ray absorption spectroscopy (EXAFS and XANES). The results indicate, as expected, that Ni occupies the octahedral sites of the spinel structure while Co occupies both tetrahedral and octahedral

J. F. Marco; J. R. Gancedo; M. Gracia; J. L. Gautier; E. R??os; F. J. Berry

2000-01-01

270

Selectivity of Na–montmorillonite in relation with the concentration of bivalent cation (Cu 2+, Ca 2+, Ni 2+) by quantitative analysis of XRD patterns  

Microsoft Academic Search

This paper aims at characterizing the structural evolution and the selectivity of a dioctahedral smectite (i.e. Wyoming montmorillonite) saturated with two different couples of cations. A reference sample was prepared by saturation with Ca2+, Cu2+ or Ni2+. The clay was dispersed in solutions of (Ca2+ and Cu2+) or (Cu2+ and Ni2+). The quantitative analysis of XRD patterns is achieved using

W. Oueslati; H. Ben Rhaiem; B. Lanson; A. Ben Haj Amara

2009-01-01

271

Combined use of GDOES, SEM?+?EDS, XRD and OM for the microchemical study of the corrosion products on archaeological bronzes  

Microsoft Academic Search

By means of the combined use of glow discharge optical emission spectrometry (GDOES), scanning electron microscopy?+?energy dispersive spectrometry (SEM?+?EDS), X-ray diffraction (XRD) and optical microscopy (OM), corrosion products, i.e., the patina, grown on archaeological leaded bronze artefacts used by Punics and Romans, have been studied. This innovative approach has been utilised in order to gain further insight into the microchemical

G. M. Ingo; E. Angelini; T. de Caro; G. Bultrini; I. Calliari

2004-01-01

272

XRD and XPS characterization of superplastic TiO2 coatings prepared on Ti6Al4V surgical alloy by an electrochemical method  

Microsoft Academic Search

X-ray diffraction (XRD) and X-Ray photoelectron spectroscopy (XPS), in conjunction with argon ion etching, were used to characterize the microstructure and the chemical composition of alkoxy-derived TiO2 coatings prepared on Ti6Al4V surgical alloy by an electrochemical method. The as-deposited oxide coatings prepared at room temperature (up to 40 µm thick) were amorphous, but transformed into nanocrystalline anatase at 550°C. Using

M. Shirkhanzadeh

1995-01-01

273

Alteration of the Callovo–Oxfordian clay from Meuse-Haute Marne underground laboratory (France) by alkaline solution. I. A XRD and CEC study  

Microsoft Academic Search

The reaction of the clay fraction of the Callovo–Oxfordian hard shale formation hosting the French underground laboratory site, with high pH NaOH, KOH and Ca(OH)2 solutions has been investigated through closed system experiments at 60, 90 and 120 °C over 6, 24 and 168 h. The mineralogical composition of the run samples has been determined using X-ray diffraction (XRD) of

S. Ram??rez; P. Vieillard; A. Bouchet; A. Cassagnabère; A. Meunier; E. Jacquot

2005-01-01

274

An X-ray diffraction (XRD) and Fourier transform infrared spectroscopic (FT-IR) characterization of the speciation of arsenic (V) in Portland cement type-V  

Microsoft Academic Search

The speciation of As(V) bearing oxyanions (AsO43?) in cementitious environment has been investigated by X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR). The hydration of Portland cement type-V(OPC-V) was found to be retarded in presence of AsO43?, and the retardation was caused mainly by the formation of highly insoluble calcium arsenate on the surface of hydrating cement particles. Arsenate

M. Yousuf A. Mollah; Felix Lu; David L. Cocke

1998-01-01

275

Anion and cation distributions in Fe(II–III) hydroxysalt green rusts from XRD and Mössbauer analysis (carbonate, chloride, sulphate, …); the “fougerite” mineral  

Microsoft Academic Search

Main crystallographic features of Fe(II–III) hydroxysalts usually named green rusts are known from XRD. However, Mössbauer spectroscopy often used to characterise them revealed that several Fe(II) sites exist that have not been elucidated yet. The structure is classified in green rust one, GR1, and green rust two, GR2, according to the sequence of stacking of Fe(OH)2 brucite-like layers that depends

Jean-Marie R. Génin; Christian Ruby

2004-01-01

276

Analysis of ferrate(VI) compounds and super-iron Fe(VI) battery cathodes: FTIR, ICP, titrimetric, XRD, UV\\/VIS, and electrochemical characterization  

Microsoft Academic Search

Chemical and electrochemical techniques are presented for the analysis of Fe(VI) compounds used in super-iron electrochemical storage cells. Fe(VI) analytical methodologies summarized are FTIR, ICP, titrimetric, UV\\/VIS, XRD Fe(VI), potentiometric, galvanostatic, cyclic voltammetry, and constant load, current or power electrochemical discharges probes. The investigated FTIR methodology becomes quantitative with introduction of an internal standard such as added barium sulfate. Electrochemical

Stuart Licht; Vera Naschitz; Leonid Halperin; Nadezhda Halperin; Lin Lin; Jianjun Chen; Susanta Ghosh; Bing Liu

2001-01-01

277

Intermediate report ESRF LT project EC70 Confocal µ-XRF and µ XRD analysis of diamond inclusions in sublithographic diamonds  

Microsoft Academic Search

In the long-term project, as the first major topic, we exploit a combination of 3D microbeam XRF and of microbeam XRD to obtain so-far inaccessible in situ information on the composition of the fluids and the structure and composition of mineral phases present in these extraordinary inclusions in diamonds of various origin. Up to now, diamonds from Sierra Leone and

K. Janssens; B. Vekemans; L. Vincze; F. Brenker

278

Comparison of XRD, XANES and TGA methods to assess the O/M ratio of Th0.60Am0.40O2-x  

NASA Astrophysics Data System (ADS)

The mixed oxide Th0.60Am0.40O2-x has been synthesized and characterized after reductive and oxidative thermal treatments. Both materials are monophasic solid solutions. The determination of O/M ratio was achieved combining XRD, XANES and TGA, showing the consistence between the three methods. This study represents a further step in our investigation of the Th-Am-O system and improves it comprehension.

Prieur, D.; Vigier, J.-F.; Rothe, J.; Somers, J.

2014-05-01

279

AFM and XRD investigation of the effect of dissolved oxygen in electrolytes on electrodeposition of CdTe on HgCdTe  

Microsoft Academic Search

CdTe films have been deposited onto HgCdTe by potentiostatic electrodeposition at deposition potentials of -0.4 V and -0.5 V with respect to a saturated calomel reference electrode in ethylene glycol base electrolyte. Films deposited with and without nitrogen bubbling to reduce dissolved oxygen in electrolytes were investigated by atomic force microscopy (AFM) and x-ray diffraction (XRD). Significant reduction in roughness

Jong-Hwa Choi; Hee Chul Lee

2002-01-01

280

Surface properties of CuCl 2/AC catalysts with various Cu contents: XRD, SEM, TG/DSC and CO-TPD analyses  

NASA Astrophysics Data System (ADS)

Surface properties of CuCl 2/activated carbon (AC) catalyst for dimethyl carbonate synthesis were studied by CO-TPD, XRD, SEM and thermogravimetry (TG)/differential scanning calorimetry (DSC) with varying Cu contents. CuCl 2/AC catalysts were prepared by impregnating AC with CuCl 2-ethanol solution in the range of Cu content from 2.8 to 18.7 wt.%. CuCl 2·2H 2O crystalline phase as active sites was gradually increased with an increase in Cu content. Appearance of CuCl 2·2H 2O was clearly identified by XRD and SEM. In relatively low Cu contents, 4.6 and 9.9 wt.%, CuCl 2·2H 2O was not detected in XRD. This indicates the formation of good dispersion of CuCl 2 compounds on activated carbon. However, DSC result revealed that CuCl 2·2H 2O was formed in multi-layers for the catalyst with Cu content more than 9.9 wt.%, which limit the catalyst activity. This fact was also strongly supported by CO-TPD experiment. The two CuCl 2/AC catalysts having Cu contents of 4.6 and 9.9 wt.% showed no difference in CO adsorption amount in TPD experiments.

Han, Man Seok; Lee, Byung Gwon; Ahn, Byoung Sung; Moon, Dong Ju; Hong, Suk In

2003-04-01

281

X-ray diffraction microtomography (XRD-CT), a novel tool for non-invasive mapping of phase development in cement materials.  

PubMed

A recently developed synchrotron-based imaging technique, X-ray diffraction microtomography (XRD-CT), has been applied here for the first time to a complex system, the hydrating Portland cement paste, in order to monitor the evolution of microstructure and phase formation with a 3D non-invasive imaging approach. The ettringite-XRD-peak-based image reconstructions, combined with transmission microtomography (X-microCT) images, allowed to assess the ubiquitous distribution of this phase, which appears early in the hydration process and showed its preferential concentration in the relatively less compact regions of the paste. The comparison of greyscale histograms for cement pastes after 9 and 58 h from hydration showed an increase of ettringite content with age, in agreement with the quantitative Rietveld analysis of the sum patterns. By renormalizing the greyscale histograms to the relative weight fraction, as obtained from Rietveld refinements, a new technique which allows estimation of phase contents with spatial resolution has been developed. The results achievable by combining XRD-CT, X-microCT and Rietveld appear very promising to provide experimental snapshots of the cement hydration process to be compared with results obtained from computer simulations. PMID:20358183

Artioli, G; Cerulli, T; Cruciani, G; Dalconi, M C; Ferrari, G; Parisatto, M; Rack, A; Tucoulou, R

2010-07-01

282

Magnetic characterization of dual phase FeZrB soft magnetic alloy  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

283

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

NASA Astrophysics Data System (ADS)

Structure and magnetic properties of Nb-doped (FeZrB) 100- xNb x 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 magnetization of the ribbons is 125.7 emu/g and the optimized annealing temperature increases from 550 to 630 °C. The morphology of the crystallized phases is observed by scanning electron microscopy. The results show that nanocrystalline ?-Fe grains are dispersed in the amorphous matrix.

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

2011-08-01

284

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

285

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

286

Magnet Mania  

NSDL National Science Digital Library

In this activity, learners explore the relationship between electric charges and magnetic fields. Learners create a magnetic field using electricity and observe its effect on the magnetic needle of a compass.

Kansas, University O.

2006-01-01

287

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

288

Structure and photocatalytic performance of magnetically separable titania photocatalysts for the degradation of propachlor  

Microsoft Academic Search

A magnetic photocatalyst was prepared by modification of TiO2 nanoparticles (Degussa P25) with nanocrystalline ?-Fe2O3 nanoparticles through a protective lining made up of two oppositely charged polyelectrolytes. As-prepared magnetically separable photocatalysts differing in ?-Fe2O3 loading (3, 8, 13, 20 and 30wt.%) were characterized by XRD, TEM, thermal analysis, Mössbauer and magnetic measurements. The photocatalytic efficiency of the nanocomposite catalysts was

V. Belessi; D. Lambropoulou; I. Konstantinou; R. Zboril; J. Tucek; D. Jancik; T. Albanis; D. Petridis

2009-01-01

289

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

290

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

291

Identification of magnetic Fe-Ti oxides in marine sediments by electron backscatter diffraction in scanning electron microscopy  

Microsoft Academic Search

In paleomagnetic and environmental magnetic studies the magnetomineralogical identification is usually based on a set of rock magnetic parameters, complemented by crystallographic and chemical information retrieved from X-ray diffraction (XRD), (electron) microscopy or energy dispersive spectroscopy (EDS) of selected samples. While very useful, each of these supplementary techniques has its limitations when applied to natural sample material which are related

C. Franke; G. M. Pennock; M. R. Drury; R. Engelmann; D. Lattard; J. F. L. Garming; T. von Dobeneck; M. J. Dekkers

2007-01-01

292

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

293

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

294

Structural and Magnetic Characteristics of p-GaAs/MnAs Nanocluster Hybrids  

NASA Astrophysics Data System (ADS)

A possible route towards semiconductor spintronic devices involves the controlled synthesis of hybrid materials that combine ferromagnetic (FM) nanoclusters within a doped semiconductor host lattice. We use molecular beam epitaxy of (Ga,Mn,Be)As followed by in situ annealing to synthesize a systematic set of samples wherein FM nanoclusters are embedded in a p-GaAs matrix. High resolution transmission electron microscopy (HRTEM) and magnetometry demonstrate our ability to reproducibly synthesize two distinct classes of materials: (a) type I samples consisting of uniformly distributed, small clusters (˜6 nm); (b) type II samples consisting of a bimodal distribution of small (˜6 nm) and large (˜25 nm) clusters. HRTEM studies show that while the large clusters are clearly MnAs with NiAs structure, the smaller clusters are possibly zinc blende in structure but with a more complex composition. We analyze the magnetic behavior of these two classes of samples and show measurements of their transport properties. Supported by the ONR-MURI program.

Rench, David; Schiffer, Peter; Samarth, Nitin

2011-03-01

295

Fabrication of surface magnetic nanoclusters using low energy ion implantation and electron beam annealing.  

PubMed

Magnetic nanoclusters have novel applications as magnetic sensors, spintronic and biomedical devices, as well as applications in more traditional materials such as high-density magnetic storage media and high performance permanent magnets. We describe a new synthesis protocol which combines the advantages of ion implantation and electron beam annealing (EBA) to produce surface iron nanoclusters. We compare the structure, composition and magnetic properties of iron nanoclusters fabricated by low dose 15 keV Fe implantation into SiO(2) followed by 1000?°C EBA or furnace annealing. Atomic force microscopy (AFM) and high resolution transmission electron microscopy (HRTEM) images together with superconducting quantum interference device (SQUID) magnetometry measurements show that only EBA leads to the rapid formation of surface crystalline Fe spherical nanoclusters, showing magnetic moments per Fe atom comparable to that of bulk bcc Fe and superparamagnetic properties. We propose a fabrication mechanism which includes e-beam enhanced desorption of SiO(2). This method has potential for fabricating nanoscale magnetic sensors integrated in microelectronic devices. PMID:21297238

Kennedy, J; Leveneur, J; Williams, G V M; Mitchell, D R G; Markwitz, A

2011-03-18

296

Magnets and Magnetism  

NSDL National Science Digital Library

This lesson demonstrates how students can apply the process of identifying main idea and supporting details to show how the force of magnetism works and how it can be useful in everyday life. The lesson provides an opportunity for students to interact with informational text and participate in a jigsaw learning activity.

2012-09-29

297

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

298

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

SciTech Connect

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

Nongjai, R.; Khan, S.; Ahmad, H.; Khan, I. [Department of Applied Physics, Zakir Hussain College of Engineering and Technology, A.M.U., Aligarh (India); Asokan, K. [Material Science Division, Inter University Accelerator Centre, New Delhi (India)

2013-06-03

299

Composition-dependent magnetic properties of BiFeO3-BaTiO3 solid solution nanostructures  

Microsoft Academic Search

We report on the Mössbauer spectra and magnetization properties of single-crystalline (BiFeO3)x-(BaTiO3)1-x solid solution nanostructures in the form of nanocubes, measuring approximately 150 to 200 nm on a side, prepared by a molten salt solid-state reaction method in the compositional range wherein 0.5<=x<=1 . Powder x-ray diffraction (XRD) and monochromatic synchrotron XRD studies indicate products of high purity, which undergo

Tae-Jin Park; Georgia C. Papaefthymiou; Arthur J. Viescas; Yongjae Lee; Hongjun Zhou; Stanislaus S. Wong; H. Zhou

2010-01-01

300

Magnetic Buoyancy  

NASA Astrophysics Data System (ADS)

`Magnetic buoyancy' is a term that is applied to two related, though definitely distinct, phenomena. This article is concerned with magnetic buoyancy as a mechanism for destabilizing atmospheres containing magnetic fields that are in mechanical equilibrium. The term is also applied to the buoyancy of an isolated tube of magnetic field; it is however important to note that this latter phenomenon i...

Hughes, D.; Murdin, P.

2000-11-01

301

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

302

Formation of bronzes during temperature-programmed reduction of MoO 3 with hydrogen—an in situ XRD and XAFS study  

Microsoft Academic Search

The temperature-programmed reduction of molybdenum trioxide (MoO3) from 300 to 773 K in 50 vol.% hydrogen in He (105 Pa) at different heating rates (0.1, 0.2, and 5 K\\/min) was investigated by in situ X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS). At heating rates of ?0.1 and ?0.2 K\\/min, the formation of the molybdenum bronze H0.34MoO3 was observed

Thorsten Ressler; Julia Wienold; Rolf E Jentoft

2001-01-01

303

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.

Kanagasabapathy, M.

304

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

PubMed Central

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

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

2012-01-01

305

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

NASA Technical Reports Server (NTRS)

A miniature CHEMIN XRD/XRF (X-Ray Diffraction/X-Ray Fluourescence) instrument is currently being developed for definitive mineralogic analysis of soils and rocks on Mars. One of the technical issues that must be addressed in order to enable XRD analysis 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 fine-grained sample to reduce preferred orientation effects and to provide a statistically significant number of crystallites to the X-ray 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 if the sample is fine-grained and randomly oriented. An Ultrasonic/Sonic Driller/Corer (USDC) currently being developed at JPL is an effective mechanism of sampling rock to produce cores and powdered cuttings. It requires low axial load (< 5N) and thus offers significant advantages for operation from lightweight platforms and in low gravity environments. The USDC is lightweight (<0.5kg), and can be driven at low power (<5W) using duty cycling. It consists of an actuator with a piezoelectric stack, ultrasonic horn, free-mass, and drill bit. The stack is driven with a 20 kHz AC voltage at resonance. The strain generated by the piezoelectric is amplified by the horn by a factor of up to 10 times the displacement amplitude. The tip impacts the free-mass and drives it into the drill bit in a hammering action. The free-mass rebounds to interact with the horn tip leading to a cyclic rebound at frequencies in the range of 60-1000 Hz. It does not require lubricants, drilling fluid or bit sharpening and it has the potential to operate at high and low temperatures using a suitable choice of piezoelectric material. To assess whether the powder from an ultrasonic drill would be adequate for analyses by an XRD/XRF spectrometer such as CHEMIN, powders obtained from the JPL ultrasonic drill were analyzed and the results were compared to carefully prepared powders obtained using a laboratory bench scale Retsch mill.

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

2003-01-01

306

Galvanostatic charge-discharge tests, 57Fe and 119Sn Mössbauer and XRD measurements on novel Sn-Ni-Fe electrodeposits  

NASA Astrophysics Data System (ADS)

Novel Sn-Ni-Fe ternary alloys were successfully deposited by pulse plating technique from an electrolyte based on sodium gluconate which acts as a complexing agent. XRD results revealed the predominantly amorphous character for the majority of the deposits. 57Fe and 119Sn conversion electron Mössbauer spectroscopy indicated the formation of a paramagnetic amorphous alloy using a short on-pulse duration and where the Fe content was less than 22 wt.%. Galvanostatic charge-discharge tests of the novel Sn-Ni-Fe deposits were carried out in a model Li-ion cell and indicated that the Sn-Ni-Fe alloys have potential as an electrode material.

Lak, G. B.; Kuzmann, E.; El-Sharif, M.; Chisholm, C. U.; Stichleutner, S.; Homonnay, Z.; Sziráki, L.

2013-04-01

307

A comprehensive review of the XRD data of the primary and secondary phases present in the BSCCO superconductor system. Part 2, Ca-Sr-Pb oxides  

SciTech Connect

X-ray powder patterns for the phases in the CaO-SrO-PbO ternary system, along with the corresponding crystal structures, were obtained from the literature and from the Powder Diffraction File (PDF). Available X-ray diffraction (XRD) patterns were compared with each other and, when possible, with a calculated pattern for each phase, yielding a recommended reference pattern. The simulated powder patterns presented here deal with the phases found within the (Ca,Sr){sub 2}PbO{sub 4} solid solution series and are recommended for the PDF.

Reardon, B.J.; Hubbard, C.R.

1992-02-01

308

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

NASA Astrophysics Data System (ADS)

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

Rahimi, Rahmatollah; Maleki, Ali; Maleki, Saied

2014-04-01

309

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

310

Novelty Preparation, Characterization and Enhancement of Magnetic Properties of MN Nanoferrites Using Safety Binder (egg White)  

NASA Astrophysics Data System (ADS)

Nanocrystalline MnFe2O4 ferrite was prepared using natural binder; egg white was used as an aqueous medium to extend nanoparticle preparation better than any other interesting materials. X-ray diffraction (XRD) and transmission electron microscope (TEM) showed also that the investigated samples revealed the nanosized structure with crystallite size of 39nm. The magnetic susceptibility measurements give a Curie temperature TC = 613K with effective magnetic moment 23 B. M. The values of magnetic constants as obtained from hysteresis data are, saturation magnetization Ms = 13.71 emu/g, remanent magnetization Mr = 0.1694 emu/g and coercivity Hc = 25.6 Oe.

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

2013-03-01

311

Synthesis of diamond in a hydrogen plasma jet: Simulations of XRD patterns of diamond polytypes and boundary layer on a substrate  

NASA Astrophysics Data System (ADS)

Two kinds of diamond film were obtained by synthesizing diamond film on Mo substrates in a hydrogen plasma jet. One (type A) was random oriented cubic diamond film with clear habit planes. The other (type B) was film with no habit plane. It was inferred that the majority of type B film consisted of oriented hexagonal diamond polytypes. In order to confirm this fact, XRD (x ray diffraction) patterns of the polytypes was simulated. From the results of the simulated XRD patterns and the analysis of SAD (selected area diffraction) patterns, it can be concluded that type B film consists mainly of a mixture of many kinds of higher hexagonal diamond polytypes, and that these polytypes show a strong bracket 110 bracket orientation in the growth direction; that is, a direction vertical to the substrate surface. The flow and temperature field just above the substrate were simulated to find growth conditions for hexagonal diamond polytypes. It was found that the polytypes could be synthesized when the temperature gradient of boundary layer is greater than the gradient at which cubic diamond is synthesized.

Kikukawa, Nobuyuki; Makino, Mitsuo; Maruyama, Katsuhisa; Shiraishi, Minoru

1993-05-01

312

Characterization of wet precipitation by X-ray diffraction (XRD) and scanning electron microscopy (SEM) in the metropolitan area of Porto Alegre, Brazil.  

PubMed

The purpose of this study is to assess the composition of wet precipitation in three sites of the metropolitan area of Porto Alegre. Besides the variables usually considered, such as pH, conductivity, major ions (Cl(-), NO(3)(-), F(-), SO(4)(2-), Na(+), K(+), Mg(2+), NH(4)(+) and Ca(2+)) and metallic elements (Cd, Co, Cr, Cu, Fe, Mn and Ni), the suspended matter was examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), with energy dispersive system (EDS), for better identification of possible anthropogenic material in this wet precipitation. Results showed an alkaline pH in the samples analyzed and higher concentrations for Na(+), Cl(-) and SO(4)(2-). The acidification and neutralization potential between anions (SO(4)(2-)+NO(3)(-)) and cations (Ca(2+)+Mg(2+)+K(+)+NH(4)(+)) showed a good correlation (0.922). The metallic elements with highest values were Zn, Fe and Mn. Results of XRD identified the presence of some minerals such as quartz, feldspar, mica, clay, carbonates and sulfates. In samples analyzed with SEM, we detected pyroxene, biotite, amphibole and oxides. Cluster analysis (CA) was applied to the data matrix to identify potential pollution sources of metals (natural or anthropogenic) and the association with minerals found in the analysis of SEM. PMID:19559525

Migliavacca, Daniela Montanari; Teixeira, Elba Calesso; Gervasoni, Fernanda; Conceição, Rommulo Vieira; Rodriguez, Maria Teresa Raya

2009-11-15

313

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

314

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

315

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

SciTech Connect

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

Kumar, Nitin [Louisiana State University; Payzant, E Andrew [ORNL; Jothimurugesan, K [Chevron Energy Technology Company; Spivey, James J [Louisiana State University

2011-01-01

316

Magnetic Fields  

NSDL National Science Digital Library

Students visualize the magnetic field of a strong permanent magnet using a compass. The lesson begins with an analogy to the effect of the earth's magnetic field on a compass. Students see the connection that the compass simply responds to the earth's magnetic field since it is the closest, strongest field, and therefore the compass will respond to the field of the permanent magnets, allowing them the ability to map the field of that magnet in the activity. This information will be important in designing a solution to the grand challenge in activity 4 of the unit.

Vu Bioengineering Ret Program

317

Magnetic properties of Acidithiobacillus ferrooxidans.  

PubMed

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

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

2013-10-01

318

Annealing effects on the microstructure and magnetic domain structures of duplex stainless steel studied by in situ technique  

NASA Astrophysics Data System (ADS)

The effects of annealing temperature on the microstructure and the magnetic domain structures of duplex stainless steel 2507 were investigated by the magnetic force microscopy (MFM), X-ray diffraction (XRD), and electron backscattered diffraction (EBSD). The MFM and XRD results indicated that the volume fraction of ferrite phase increased with increasing annealing temperature, but the lattice constants kept constant. Moreover, with the rise of annealing temperature, the magnetic domain structure in the ferrite phase varied gradually, where the magnetic domain became thinner and the distribution turned more homogeneous. These results gave a direct evidence for the changes of microstructure and magnetic domain structure induced by the annealing treatment. EBSD analysis showed that the orientation of ferrite grains changed after annealing treatments, which coincided with the changes of the microstructure and the magnetic domain structures.

Guo, L. Q.; Zhao, X. M.; Li, M.; Zhang, W. J.; Bai, Y.; Qiao, L. J.

2012-10-01

319

Titania deposited on soft magnetic activated carbon as a magnetically separable photocatalyst with enhanced activity  

NASA Astrophysics Data System (ADS)

Magnetically separable composite photocatalysts, TiO 2 deposited on soft magnetic ferrite activated carbon (TFAC), were prepared by sol-gel and dip-coating technique. The prepared composites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectra (FTIR), optical absorption spectroscopy, vibrating sample magnetometer (VSM) and nitrogen adsorption. These photocatalysts exhibited enhanced photocatalytic activity compared to Degussa P25 for the degradation of methyl orange (MO) in aqueous solution. The kinetics of MO degradation was well fitted to the Langmuir-Hinshelwood model. The samples showed good magnetic response and could be completely recovered by an external magnet. Furthermore, the photocatalysts could maintain high photocatalytic activity after five cycles, and the degradation rate of MO was still close to 90%.

Wang, Shaohua; Zhou, Shaoqi

2010-08-01

320

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.

Center, National G.; Noaa

321

Photoinduced Magnetism.  

National Technical Information Service (NTIS)

Remarkable progress has been achieved in our investigations of photo induced magnetism (PIM) in several families of molecule-based magnets during the past three years. The advancements include development of utilization of a new experimental method in stu...

A. J. Epstein

2003-01-01

322

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.

Workshop, Mission S.

2013-01-01

323

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.

324

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

325

Vertically ordered magnetic EuTe quantum dots stacks on SnTe matrices.  

PubMed

Stacked EuTe magnetic quantum dots (QDs) separated by SnTe spacers of increasing thickness were grown and studied using x-ray diffraction (XRD) and electron microscopy. Grazing incidence XRD indicated that the EuTe QDs are under compressive in-plane strain. Both XRD analysis and microscopy images demonstrated that the EuTe QDs are vertically aligned, as a result of the strain field produced by buried QDs. The width of the lateral error distribution in the QDs' vertical alignment from layer to layer decreases for thinner SnTe spacers, corresponding to more stressed SnTe matrices. The system can be, therefore, tuned to explore magnetic interactions between QDs. The results are discussed in the light of previous elastic strain models in anisotropic matrices from the literature. PMID:22156149

Díaz, B; Malachias, A; Montoro, L A; Rappl, P H O; Abramof, E

2012-01-13

326

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

327

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.

328

Superconducting magnets  

SciTech Connect

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

Not Available

1994-08-01

329

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

330

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

331

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

332

Magnetizing of permanent magnets using HTS bulk magnets  

NASA Astrophysics Data System (ADS)

A demagnetized Nd-Fe-B permanent magnet was scanned just above the magnetic pole which contains the HTS bulk magnet generating a magnetic field of 3.27 T. The magnet sample was subsequently found to be fully magnetized in the open space of the static magnetic fields. We examined the magnetic field distributions when the magnetic poles were scanned twice to activate the magnet plate inversely with various overlap distances between the tracks of the bulk magnet. The magnetic field of the "rewritten" magnet reached the values of the magnetically saturated region of the material, showing steep gradients at the border of each magnetic pole. As a replacement for conventional pulse field magnetizing methods, this technique is proposed to expand the degree of freedom in the design of electromagnetic devices, and is proposed as a novel practical method for magnetizing rare-earth magnets, which have excellent magnetic performance and require intense fields of more than 3 T to be activated.

Oka, Tetsuo; Muraya, Tomoki; Kawasaki, Nobutaka; Fukui, Satoshi; Ogawa, Jun; Sato, Takao; Terasawa, Toshihisa

2012-01-01

333

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

334

A comprehensive review of the XRD data of the primary and secondary phases present in the BSCCO superconductor system: Part 1, Ca-Sr-Cu oxides  

SciTech Connect

X-ray powder patterns for the phases in the CaO-SrO-CuO ternary system, along with the corresponding crystal structures, were obtained from the literature and from the Powder Diffraction File (PDF). Available X-ray diffraction (XRD) patterns were compared with each other and, when possible, with a simulated pattern for each phase, yielding a recommended reference pattern. The simulated powder patterns presented here deal with the phases found within the (Ca, Sr)O, (Ca,Sr){sub 2}CuO{sub 3}, (Ca,Sr){sub 14}Cu{sub 24}O{sub 41}, (Ca,Sr)CuO{sub 2}, (Ca,Sr)Cu{sub 2}O{sub 3}, and (Ca,Sr)Cu{sub 2}O{sub 2} solid solution series and are recommended for the PDF.

Reardon, B.J. [Alfred Univ., NY (United States); Hubbard, C.R. [Oak Ridge National Lab., TN (United States)

1992-01-01

335

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 3^{2-} 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

336

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

337

AFM and XRD investigation of the effect of dissolved oxygen in electrolytes on electrodeposition of CdTe on HgCdTe  

NASA Astrophysics Data System (ADS)

CdTe films have been deposited onto HgCdTe by potentiostatic electrodeposition at deposition potentials of -0.4 V and -0.5 V with respect to a saturated calomel reference electrode in ethylene glycol base electrolyte. Films deposited with and without nitrogen bubbling to reduce dissolved oxygen in electrolytes were investigated by atomic force microscopy (AFM) and x-ray diffraction (XRD). Significant reduction in roughness (>1 orders) was observed by bubbling the electrolyte with 6 N nitrogen gas and the resulting films were highly oriented. The reduction in roughness is believed to be the result of the suppression of the reduction reaction whereby the dissolved molecular oxygen is converted to hydrogen peroxide and water that disturbs the ordered CdTe electrodeposition onto HgCdTe wafers.

Choi, Jong-Hwa; Lee, Hee Chul

2002-03-01

338

Synthesis, structure and magnetic properties of the new oxygen-deficient perovskite Na 3MnV 2O 7.5  

NASA Astrophysics Data System (ADS)

The new ternary vanadate Na 3MnV 2O 7.5 has been synthesized by solid state reaction route. Its crystal structure was determined from both powder X-ray diffraction data and high-resolution transmission electron microscopy (HRTEM) analysis. Na 3MnV 2O 7.5 ( P2 /c, a = 7.4004(4) Å, b = 5.6065(3) Å, c = 17.0876(11) Å, ? = 90.0114(2) °, and Z = 4) crystallizes with a new type of oxygen-deficient perovskite ABO 3-? ( ? = 1/2) with the sodium atoms occupying the A site and the vanadium and manganese atoms perfectly ordered in the B site. In Na 3MnV 2O 7.5 the manganese and the vanadium atoms are octahedral and tetrahedral coordinated, respectively. The MnO 6 and VO 4 polyhedra share edges and form a perovskite 3D-framework with high disorder of the oxygen atoms. HRTEM confirmed this structural model. Na 3MnV 2O 7.5 was characterized by magnetic susceptibility and specific heat measurements. It is antiferromagnetic with no magnetic ordering down to 2 K.

Ben Yahia, Hamdi; Gaudin, Etienne; Boulahya, Khalid; Darriet, Jacques

2011-06-01

339

Ceria-based Catalysts for the Production of H2 Through the Water-gas-shift Reaction: Time-Resolved XRD and XAFS Studies  

SciTech Connect

Hydrogen is a potential alternate energy source for satisfying many of our energy needs. In this work, we studied H2 production from the water-gas-shift (WGS) reaction over Ce1-x Cu x O2 catalysts, prepared with a novel microemulsion method, using two synchrotron-based techniques: time-resolved X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS). The results are compared with those reported for conventional CuO x /CeO2 and AuO x /CeO2 catalysts obtained through impregnation of ceria. For the fresh Ce1-x Cu x O2 catalysts, the results of XAFS measurements at the Cu K-edge indicate that Cu is in an oxidation state higher than in CuO. Nevertheless, under WGS reaction conditions the Ce1-x Cu x O2 catalysts undergo reduction and the active phase contains very small particles of metallic Cu and CeO2-x . Time-resolved XRD and XAFS results also indicate that Cud+ and Aud+ species present in fresh CuO x /CeO2 and AuO x /CeO2 catalysts do not survive above 200 C under the WGS conditions. In all these systems, the ceria lattice displayed a significant increase after exposure to CO and a decrease in H2O, indicating that CO reduced ceria while H2O oxidized it. Our data suggest that H2O dissociation occurred on the Ovacancy sites or the Cu-Ovacancy and Au-Ovacancy interfaces. The rate of H2 generation by a Ce0.95Cu0.05O2 catalyst was comparable to that of a 5 wt% CuO x /CeO2 catalyst and much bigger than those of pure ceria or CuO.

Wang,X.; Rodriguez, J.; Hanson, J.; Gamarra, D.; Marinez-Arias, A.; Fernandez-Garcia, M.

2008-01-01

340

Free volume in ionic liquids: a connection of experimentally accessible observables from PALS and PVT experiments with the molecular structure from XRD data.  

PubMed

In the current work, free volume concepts, primarily applied to glass formers in the literature, were transferred to ionic liquids (ILs). A series of 1-butyl-3-methylimidazolium ([C4MIM](+)) based ILs was investigated by Positron Annihilation Lifetime Spectroscopy (PALS). The phase transition and dynamic properties of the ILs [C4MIM][X] with [X](-) = [Cl](-), [BF4](-), [PF6](-), [OTf](-), [NTf2](-) and [B(hfip)4](-) were reported recently (Yu et al., Phys. Chem. Chem. Phys., 2012, 14, 6856-6868). In this subsequent work, attention was paid to the connection of the free volume from PALS (here the mean hole volume, ) with the molecular structure, represented by volumes derived from X-ray diffraction (XRD) data. These were the scaled molecular volume Vm,scaled and the van der Waals volume V(vdw). Linear correlations of at the "knee" temperature ((T(k))) with V(m,scaled) and V(vdw) gave good results for the [C4MIM](+) series. Further relationships between volumes from XRD data with the occupied volume Vocc determined from PALS/PVT (Pressure Volume Temperature) measurements and from Sanchez-Lacombe Equation of State (SL-EOS) fits were elaborated (V(occ)(SL-EOS) ? 1.63 V(vdw), R(2) = 0.981 and V(occ)(SL-EOS) ? 1.12 V(m,scaled), R(2) = 0.980). Finally, the usability of V(m,scaled) was justified in terms of the Cohen-Turnbull (CT) free volume theory. Empirical CT type plots of viscosity and electrical conductivity showed a systematic increase in the critical free volume with molecular size. Such correlations allow descriptions of IL properties with the easily accessible quantity V(m,scaled) within the context of the free volume. PMID:23640471

Beichel, Witali; Yu, Yang; Dlubek, Günter; Krause-Rehberg, Reinhard; Pionteck, Jürgen; Pfefferkorn, Dirk; Bulut, Safak; Bejan, Dana; Friedrich, Christian; Krossing, Ingo

2013-06-14

341

HT-XRD study of synthetic ferrian magnesian spodumene: the effect of site dimension on the P21/c-->C2/c phase transition  

NASA Astrophysics Data System (ADS)

Ferrian magnesian spodumene was synthesized in the MLFSH system at P=0.4 GPa, T=700 °C, fO2=NNO+2.3. The space group at room T is P21/c [a=9.638(3) Å, b=8.709(2) Å, c=5.258(2) Å, ?=109.83(3)?, V=415.2 Å3]. The structure is topologically equivalent to that of ferrian spodumene, LiFeSi2O6, and has two symmetrically independent tetrahedral chains, A and B, and two independent octahedral sites, M1 and M2. The crystal-chemical composition was determined combining EMP, SIMS and single-crystal XRD analysis, yielding M2(Li0.85Mg0.09Fe2+0.06) M1(Fe3+0.85Mg0.15)Si2O6. Li is ordered at the M2 site and Fe3+ is ordered at the M1 site, whereas Mg (and Fe2+) distribute over both octahedral sites. Structure refinements done at different temperatures (25, 70, 95, 125, 150 and 200 °C) allowed characterization of a reversible displacive P21/c-->C2/c transition at 106 °C. Previous HT-XRD studies of Li-clinopyroxenes had shown that the transition temperature is inversely related to the size of the M1 cation. For the crystal of this work, the aggregate ionic radius at M1 is longer than that of ferrian spodumene, for which the transition temperature is -44 °C. The higher transition temperature observed can only be explained on the basis of the shorter aggregate radius at the M2 site (due to the presence of Mg substituting after Li), in keeping with the results obtained for ferromagnesian P21/c pyroxenes. The effects of all the chemical substitutions must be considered when modelling transition temperatures and thermodynamic behaviour in clinopyroxenes.

Cámara, F.; Iezzi, G.; Oberti, R.

342

Synthesis, characterization and magnetic behavior of Co/MCM-41 nano-composites  

NASA Astrophysics Data System (ADS)

Synthesis, structure and magnetic properties of Co/MCM-41 as magnetic nano-composites have been investigated. Mesoporous materials with different degrees of metal loading were prepared by wet impregnation and characterized by ICP, XRD, N2 adsorption, UV-vis DRS, TPR and EPMA-EDS. Cobalt oxide clusters and Co3O4 nano-particles could be confined inside the mesopores of MCM-41, being this fact favored by the Co loading increasing. In addition, larger crystals of Co3O4 detectable by XRD also grow on the surface when the Co loading is enhanced. The magnetic characterization was performed in a SQUID magnetometer using a maximum magnetic applied field µ0Ha=1 T. While the samples with the higher Co loadings showed a behavior typically paramagnetic, a superparamagnetic contribution is more notorious for lower loadings, suggesting high Co species dispersion.

Cuello, N.; Elías, V.; Crivello, M.; Oliva, M.; Eimer, G.

2013-09-01

343

Magnetic and charge derived properties of ball milled dilute magnetic semiconductor Si0.98Mn0.02  

NASA Astrophysics Data System (ADS)

The dilute magnetic semiconductor (DMS) material Si0.98Mn0.02 was prepared by a ball milling technique at two different milling periods. The samples have been analyzed for electron density distribution and local structure using powder X-ray diffraction (XRD) data sets. The results were compared with those of pure silicon. Structural changes and their implications on the bond-length distributions were analyzed and compared. Electron density distributions of the defect structure were plotted on 2D planes and along the bonding direction in the unit cell for each case using the maximum entropy method (MEM). The incorporation of transition metal ion (Mn) at substitutional sites of the host lattice (Si) is verified for Si0.98Mn0.02 from XRD and magnetic hysteresis measurements were taken using vibrating sample magnetometer (VSM). Room temperature ferromagnetism due to Mn substitution was observed in the prepared samples.

Sheeba, R. A. J. R.; Saravanan, R.; Sasikumar, S.

2013-10-01

344

Magnetic properties of iron/graphite core shell nanoparticles prepared by annealing of Fe C N-based nanocomposite  

NASA Astrophysics Data System (ADS)

We are reporting the phase composition and magnetic properties of the core-shell structured iron/graphite nanoparticles formed during annealing of a nanopowder prepared by laser pyrolysis of gas phase reactants. The originally synthesized Fe-C-N-based nanocomposite powder was characterized by TEM, XRD and magnetic measurements. The nanopowder was heated up to 800 °C in vacuum. The presence of iron nanoparticles with a mean diameter of 40 nm in the annealed state of the nanopowder was proved by XRD and TEM analysis. Mössbauer spectroscopy was used for the characterization of the synthesized/annealed nanopowder to prove the qualitative change in the phase composition.

David, B.; Pizúrová, N.; Schneeweiss, O.; Bezdi?ka, P.; Alexandrescu, R.; Morjan, I.; Crunteanu, A.; Voicu, I.

2005-04-01

345

Magnetic and transport properties of oxide thin films  

Microsoft Academic Search

My dissertation research focuses on the investigation of the transport and magnetic properties of transition metal and rare earth doped oxides, particularly SnO2 and HfO2 thin films. Cr- and Fe-doped SnO 2 films were deposited on Al2O3 substrates by pulsed-laser deposition. X-ray-diffraction patterns (XRD) show that the films have rutile structure and grow epitaxially along the (101) plane. The diffraction

Yuanjia Hong

2007-01-01

346

Magnetic imaging method based on magnetic relaxation of magnetic nanoparticles  

Microsoft Academic Search

We present a well-posed magnetic imaging method based on magnetic relaxation of magnetic nanoparticles for obtaining high-spatial resolution image of magnetic tracers. The method relies on the principle that Néel relaxation of the magnetic nanoparticles is faster in a finite magnetic field than in the absence of the field. The magnetic nanoparticles are used as signal generator and a superconducting

S. Sarangi; I. C. Tan; A. Brazdeikis

2009-01-01

347

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

348

Magnetism in Transition Element Doped In2O3 Dilute Magnetic Semiconductors  

NASA Astrophysics Data System (ADS)

There is currently a tremendous research effort in the area of dilute magnetic semiconductors (DMS). It is proposed that a DMS exhibiting ferromagnetic properties at room temperature could be used in a new class of devices termed spintronics. Whereas standard electronics work on the principle of manipulation of charge properties of an electron, spintronics work on controlling electron spin. Indium oxide is a wide band gap semiconductor with unique optical and electrical properties. Defect concentrations such as transition metal doping and oxygen vacancies in In2O3 can tune the electrical/magnetic behavior from ferromagnetic metal-like to ferromagnetic semiconducting to paramagnetic insulating. Bulk materials of magnetic element (Fe, Co and Cr) doped In2O3 have been made using a standard solid state reaction method. Structural and magnetic properties have been measured using standard techniques. XRD analysis confirmed single phase In2O3 with no impurity phases due to addition of magnetic elements. Magnetization as a function of applied magnetic field and temperature were collected on all the samples using a SQUID magnetometer. Detailed structural and magnetic properties will be presented in this talk.

Langhoff, M.; Nahlik, E.; Kolekar, Y.; Kahol, P.; Ghosh, K.

2012-02-01

349

Electroplating hard magnetic SmCo for magnetic microactuator applications  

NASA Astrophysics Data System (ADS)

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

Chen, Jue; Rissing, Lutz

2011-04-01

350

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

351

Effect of magnetic fields on melt-spun Nd2Fe14B-based ribbons  

NASA Astrophysics Data System (ADS)

The effect of a magnetic field on microstructure and magnetic properties of Nd2Fe14B-based melt-spun ribbons is investigated. The magnetic field was applied in perpendicular or parallel direction to the ribbon plane during quench with a field strength up to several kilo Oersteds. The XRD patterns and TEM graphs show a strong grain size reduction upon the magnetic field application. The magnetic field also enhances the (00l) texture of ribbons when the field is perpendicular to the ribbon plane. The refined microstructure with significantly reduced grain size leads to enhanced magnetic exchange interactions between the hard and soft phases in the Nd2Fe14B/Fe nanocomposite ribbons. This magnetic field-assisted melt-spinning technique is promising for producing nanocomposite magnets with enhanced energy density.

Van Nguyen, Vuong; Rong, Chuanbing; Ding, Yong; Liu, J. Ping

2012-04-01

352

A Highly Sensitive and Efficient Functionalized Magnetic Chemosensor for Cu2+ Removal  

NASA Astrophysics Data System (ADS)

Fe3O4 nanoparticles were covalently functionalized by N-(quinoline-8-yl)-2-(3-triethoxysilyl-propylamino)- acetamide (QTPA), and finally utilized to be magnetic chemosensor for sensitive and efficient Cu2+ removal in aqueous solution. Fourier FT-IR, TEM, XRD and XPS results showed that QTPA was bonded to the surface of Fe3O4 nanoparticles. At room temperature, the magnetic chemosensor exhibited high removal efficiency towards Cu2+.

Kong, Xiangfeng; Chen, Yuxiang; Yang, Zaixiang; Wang, Shixing; Zhou, Yang

353

Novelty, preparation, characterization and enhancement of magnetic properties of Mn nanoferrites using safety binder (egg white)  

NASA Astrophysics Data System (ADS)

Nanocrystalline MnFe 2O 4 ferrite was prepared by using autocombustion technique ( flash). The microstructure and magnetic properties are studied. The results of XRD and TEM clarified that, this ferrite is nanosized with particle size (39 nm). Magnetic measurements showed a ferromagnetic behavior with T C = 613 K, the saturation magnetization M s = 13.71 emu/g, remanent magnetization M r = 0.1694 emu/g and, coercivity H c = 25.6 Oe. Natural material, egg white used as an aqueous medium to extend prepare nanoparticles better than other chemical interesting materials.

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

2011-10-01

354

Preparation of magnetically responsive albumin nanospheres and in vitro drug release studies.  

PubMed

In this work, doxorubicin (DOX)-loaded magnetic albumin nanospheres were prepared using desolvation method in order to develop magnetically responsive nanocarrier system. Nanoparticles were characterized with zetasizer, SEM, AFM, XRD and magnetometer. In vitro DOX release was also investigated. It was found that nanoparticles had spherical shape with narrow size distributions and had magnetic responsiveness. In addition, slower drug release was observed with nanoparticulate system compared with free DOX. Moreover, the release rate should accelerate at target sites (cancer cells or tissue) where proteolytic enzymes are more abundant as known; therefore, magnetic albumin nanospheres can be effective potential DOX carrier with targeting ability. PMID:23419121

Ak, Güliz; Y?lmaz, Habibe; Sanl?er, Senay Hamarat

2014-02-01

355

Preparation and Characterization of Chitosan Poly(acrylic acid) Magnetic Microspheres  

PubMed Central

Spherical microparticles, capable of responding to magnetic fields, were prepared by encapsulating dextran-coated Fe3O4 nanoparticles into chitosan poly(acrylic acid) (PAA) microspheres template. The obtained magnetic microspheres were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and thermogravimetry (TG). The results showed that the microspheres were formed and demonstrated magnetic behavior in an applied magnetic field. In addition, magnetite particles were well encapsulated and the composite particles have high magnetite content, which was more than 40%.

Guo, Liang; Liu, Guang; Hong, Ruo-Yu; Li, Hong-Zhong

2010-01-01

356

Magnetic nanoparticles  

Microsoft Academic Search

Intrinsic properties of magnetic nanoparticles are reviewed, with special emphasis on the effects of finite size on zero-temperature spin ordering, magnetic excitations, and relaxation. Effects on zero-temperature spin ordering include moment enhancement due to band narrowing in 3d transition metal particles, surface spin disorder in ferrite particles, and multi-sublattice states in antiferromagnetic oxide particles. Magnetic excitations include discretized spin wave

R. H Kodama

1999-01-01

357

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

358

Magnetic Fluids  

NSDL National Science Digital Library

In this fun, engaging activity, students are introduced to a unique type of fluidâferrofluidsâwhose 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.

University Of Houston

359

Animal Magnetism  

NSDL National Science Digital Library

This radio broadcast looks at the mysterious way in which certain animals can travel vast distances around the planet, using the magnetic field of Earth to guide them. Migrating birds, fish, sea turtles, honey bees and even bacteria have all been found to navigate using the magnetic field of Earth, sometimes over quite enormous distances and reaching targets of only a few degrees in width. There is discussion about where magnetic receptors may be within animals and that particular cells in migratory creatures contain magnetite, a substance which humans used many hundreds of years ago to create the first compass. This radio broadcast discusses animal magnetism with researchers who have been working with sea turtles, to discover just how the turtles find their way back to the same beaches every year to lay their eggs. There is explanation of how the magnetic sense in animals has two components: acting as a compass to guide them and providing them with location; and how this seems to be possible since the magnetic field gets stronger in higher latitudes and inclination angle (the angle of the magnetic field to the surface of Earth) changes over different points on Earth. The broadcast also explains why creatures such as honey bees and even bacteria need to be in tune with the magnetic field of Earth, and how magnetic sense is prevalent in many animals with seemingly no need for it. The broadcast is 29 minutes in length.

360

Planetary Magnetism  

SciTech Connect

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.

1980-02-01

361

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

NASA Astrophysics Data System (ADS)

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

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

2004-05-01

362

Optical and magnetic properties of zinc oxide quantum dots doped with cobalt and lanthanum.  

PubMed

Cobalt and Lanthanum-doped ZnO QDs are synthesized by a modified sol-gel method under atmospheric conditions. The as-prepared quantum dots are characterized by X-ray powder diffraction (XRD), energy dispersive X-ray (EDX) analysis and high resolution transmission electron microscopy (HRTEM). The optical properties of the products are studied by fluorescent spectroscopy. With a proper Co and La doping, these nanoparticles possess exceptionally small size and enhanced fluorescence. Hysteresis loops of un-doped ZnO QDs and Co and La-doped ZnO QDs indicate that both the samples show ferromagnetic behavior at room temperature. Finally, these nanoparticles can label the BGC 803 cells successfully in short time and present no evidence of toxicity or adverse affect on cell growth even at the concentration up to 1 mM. We expect that the as-prepared Co and La-doped ZnO QDs can provide a better reliability of the collected data and find promising applications in biological, medical and other fields. PMID:23862449

Yu, Shiyong; Zhao, Jing; Su, Hai-Quan

2013-06-01

363

Uranium speciation as a function of depth in contaminated hanford sediments--a micro-XRF, micro-XRD, and micro- and bulk-XAFS study.  

PubMed

The distribution and speciation of U and Cu in contaminated vadose zone and aquifer sediments from the U.S. DOE Hanford site (300 Area) were determined using a combination of synchrotron-based micro-X-ray fluorescence (microXRF) imaging, micro-X-ray absorption near edge structure (microXANES) spectroscopy, and micro-X-ray diffraction (microXRD) techniques combined with bulk U LIII-edge X-ray absorption fine structure (XAFS) spectroscopy. Samples were collected from within the inactive North Process Pond (NPP2) at 8 ft (2.4 m, NPP2-8) depth and 12 ft (3.7 m, NPP2-12) depth in the vadose zone, and fines were isolated from turbid groundwater just below the water Table (12-14 ft, approximately 4 m, NPP2-GW). microXRF imaging, microXRD, and microXANES spectroscopy revealed two major U occurrences within the vadose and groundwater zones: (1) low to moderate concentrations of U(VI) associated with fine-textured grain coatings that were consistently found to contain clinochlore (referred to here as chlorite) observed in all three samples, and (2) U(VI)-Cu(II) hotspots consisting of micrometer-sized particles associated with surface coatings on grains of muscovite and chlorite observed in samples NPP2-8' and NPP2-GW. In the aquifer fines (NPP2-GW), these particles were identified as cuprosklodowskite (cps: Cu[(UO2)(SiO2OH)]2 x 6H2O) and metatorbernite (mtb: Cu(UO2)2(PO4)2 x 8H2O). In contrast, the U-Cu-containing particles in the vadose zone were X-ray amorphous. Analyses of U LIII-edge XAFS spectra by linear-combination fitting indicated that U speciation consisted of (1) approximately 75% uranyl sorbed to chlorite and approximately 25% mtb-like X-ray amorphous U-Cu-phosphates (8 ft depth), (2) nearly 100% sorbed uranyl (12 ft depth), and (3) approximately 70% uranyl sorbed to chlorite and approximately 30% cps/mtb (groundwater zone). These findings suggest that dissolution of U(VI)-Cu(II)-bearing solids as well as desorption of U(VI), mainly from phyllosilicates, are important persistent sources of U(VI) to the associated uranium groundwater plume in Hanford Area 300. PMID:19244994

Singer, David M; Zachara, John M; Brown, Gordon E

2009-02-01

364

Corrensite and mixed-layer chlorite/corrensite in metabasalt from northern Taiwan: TEM/AEM, EMPA, XRD, and optical studies  

NASA Astrophysics Data System (ADS)

Many chloritic minerals in low-grade metamorphic or hydrothermally altered mafic rocks exhibit abnormal optical properties, expand slightly upon glycolation (“expandable chlorite”) and/or have excess AlVI relative to AlIV, as well as significant Ca, K and Na contents. Chloritic minerals with these properties fill vesicles and interstitial void space in low-grade metabasalt from northern Taiwan and have been studied with a combination of TEM/AEM, EMPA, XRD, and optical microscopy. The chloritic minerals include corrensite, which is an ordered 1:1 mixed-layer chlorite/smectite, and “expandable chlorite”, which is shown to be a mixed-layer chlorite/corrensite. Corrensite and some mixed-layer chlorite/corrensite occur as rims of vesicles and other cavities, while later-formed mixed-layer chlorite/corrensite occupies the vesicle cores. The TEM observations show that the mixed-layer chlorite/corrensite has ca. 20%, and the corrensite has ca. 50% expandable smectite-like layers, consistent with XRD observations and with their abnormal optical properties. The AEM analyses show that high Si and Ca contents, high AlVI/AlIV and low FeVI/(Fe+Mg)VI ratios of “chlorites” are correlated with interstratification of corrensite (or smectite-like) layers in chlorite. The AEM analyses obtained from 200 500 Å thick packets of nearly pure corrensite or chlorite layers always show that corrensite has low AlIV/SiIV and low FeVI/(Fe+Mg)VI, while chlorite has high AlIV/SiIV and high FeVI/(Fe+Mg)VI. This implies that the trioctahedral smectite-like component of corrensite has significantly lower AlIV/SiIV and FeVI/(Fe+Mg)VI. The ratios of FeVI/(Fe+Mg)VI and AlIV/SiIV thus decrease in the order chlorite, corrensite, smectite. The proportions of corrensite (or smectite-like) layers relative to chlorite layers in low-grade rocks are inferred to be controlled principally by Fe/Mg ratio in the fluid or the bulk rock and by temperature. Compositional variations of “chlorites” in low-grade rocks, which appear to correlate with temperature or metamorphic grade, more likely reflect variable proportions of mixed-layered components. The assemblages of trioctahedral phyllosilicates tend to occur as intergrown discrete phases, such as chlorite-corrensite, corrensite-smectite, or chlorite-corrensite-smectite. A model for the corrensite crystal structure suggests that corrensite should be treated as a unique phase rather than as a 1:1 ordered mixed-layer chlorite/smectite.

Shau, Yen-Hong; Peacor, Donald R.; Essene, Eric J.

1990-03-01

365

Synthesis, characterization and magnetic properties of nanocrystalline nickel  

NASA Astrophysics Data System (ADS)

Nickel nanoparticles were synthesized by thermal decomposition route with using cappant as Triphenyl phosphine (TPP). The product was characterized in details by X-ray diffraction; transmission electron microscope and Fourier transform infrared techniques. From XRD the particles size was 1.22 nm. But from TEM results it was shown that about 10nm. This was due to the particles were covered by cappant. Magnetic measurement was carried out by vibrating sample magnetometer (VSM). Magnetic measurement attributed to the result of superparamagnetic behavior at 4K and also at 300K. So nickel nanoparticles of size 1.22 nm behave as superparamagnetic particles in the temperature range 4K-300K.

Das, Sourav; Lalla, N. P.; Okram, G. S.

2013-02-01

366

Magnetic Recording.  

ERIC Educational Resources Information Center

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

Lowman, Charles E.

367

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

368

Speleothem magnetism  

NASA Astrophysics Data System (ADS)

The magnetic recordings preserved in calcite speleothems and the nature of their constituent magnetic minerals hold enormous potential for paleomagnetic and paleoenvironmental reconstructions. Speleothems lock magnetization in instantly, are not affected by post-depositional effects, and can be dated with high precision. The natural remanence in speleothems is carried mainly by magnetite, and the main remanence acquisition mechanism is depositional, through physical alignment of detrital magnetic grains parallel to the Earth's magnetic field. Detrital particles are deposited on speleothem surfaces either from receding flood waters, or directly from drip water percolating through overlying rock and soil. Chemical remanence, acquired in situ by particles growing through a critical volume, is of secondary importance. Previous studies of speleothem magnetism have shown that geomagnetic features are successfully recorded by speleothems, and can be reproduced at a local and regional scale. Future studies that benefit from increasingly sensitive magnetometers, operating at high spatial resolution, should be able to resolve short-term geomagnetic variability, and characterize events such as geomagnetic excursions at an unprecedented scale. The environmental magnetism of speleothems is still an untapped reservoir, but holds the promise of bridging the gap between mineral-magnetic records from other sedimentary archives and established speleothem environmental proxies (e.g., oxygen and carbon isotopes).

Lascu, Ioan; Feinberg, Joshua M.

2011-11-01

369

Analysis of ferrate(VI) compounds and super-iron Fe(VI) battery cathodes: FTIR, ICP, titrimetric, XRD, UV/VIS, and electrochemical characterization  

NASA Astrophysics Data System (ADS)

Chemical and electrochemical techniques are presented for the analysis of Fe(VI) compounds used in super-iron electrochemical storage cells. Fe(VI) analytical methodologies summarized are FTIR, ICP, titrimetric, UV/VIS, XRD Fe(VI), potentiometric, galvanostatic, cyclic voltammetry, and constant load, current or power electrochemical discharges probes. The investigated FTIR methodology becomes quantitative with introduction of an internal standard such as added barium sulfate. Electrochemical techniques which utilize a solid cathode, and spectroscopic techniques which utilize a solid sample, are preferred over solution phase techniques. The titrimetric methodology (chromite analysis) has been detailed, and adjusted to determine the extent of Fe(VI?III) oxidation power in both unmodified or coated Fe(VI) compounds. Fe(VI) compounds have also been variously referred to as ferrates or super-iron compounds, and include K 2FeO 4 and BaFeO 4. Such compounds are highly oxidizing, and in the aqueous phase the full three electron cathodic charge capacity has been realized, as summarized by reactions such as: FeO 42-+5/2H 2O+3e -?1/2Fe 2O 3+5OH -.

Licht, Stuart; Naschitz, Vera; Halperin, Leonid; Halperin, Nadezhda; Lin, Lin; Chen, Jianjun; Ghosh, Susanta; Liu, Bing

370

Investigation of irradiation effects induced by self-ion in 6H-SiC combining RBS/C, Raman and XRD  

SciTech Connect

Single crystals of 6H-SiC were irradiated at room temperature and 670 K with 4 MeV C ions at two fluences: 1015 and 1016 cm2 (0.16 and 1.6 dpa at the damage peak). Damage accumulation was studied by a combination of X-ray diffraction (XRD), Raman spectroscopy and Rutherford backscattering spectrometry in channelling geometry (RBS/C) along the [0001] direction. The irradiated layer is found to be composed of a low damage region up to 1.5 lm followed by a region where the disorder level is higher, consistent with SRIM predictions. At room temperature and low fluence, typically 1015 cm2, the strain depth profile follows the dpa depth distribution (with a maximum value of 2%). The disorder is most likely due to small defect clusters. When increasing the fluence up to 1016 cm2, a buried amorphous layer forms, as indicated by e.g. Raman results where the Si C bands become broader or even disappear. At a higher irradiation temperature of 670 K, amorphization is not observed at the same fluence, revealing a dynamic annealing process. However, results tend to suggest that the irradiated layer is highly heterogeneous and composed of different types of defects.

Chaabane, Nihed [CEA, Saclay, France; Debelle, Aurelien [Universite Paris Sud, Orsay, France; Sattonnay, Gael [Universite Paris Sud, Orsay, France; Trocellier, Patrick [CEA, Saclay, France; Serruys, Yves [CEA, Saclay, France; Thome, Lionel [Universite Paris Sud, Orsay, France; Zhang, Yanwen [ORNL; Weber, William J [ORNL; Meis, Constantin [CEA, Saclay, France; Gosmain, Lionel [CEA, Saclay, France; Boulle, Alexandre [SPCTS, Limoges Cedex, France

2012-01-01

371

Investigation of irradiation effects induced by self-ion in 6H-SiC combining RBS/C, Raman and XRD  

NASA Astrophysics Data System (ADS)

Single crystals of 6H-SiC were irradiated at room temperature and 670 K with 4 MeV C ions at two fluences: 1015 and 1016 cm-2 (0.16 and 1.6 dpa at the damage peak). Damage accumulation was studied by a combination of X-ray diffraction (XRD), Raman spectroscopy and Rutherford backscattering spectrometry in channelling geometry (RBS/C) along the [0 0 0 1] direction. The irradiated layer is found to be composed of a low damage region up to ˜1.5 ?m followed by a region where the disorder level is higher, consistent with SRIM predictions. At room temperature and low fluence, typically 1015 cm-2, the strain depth profile follows the dpa depth distribution (with a maximum value of ˜2%). The disorder is most likely due to small defect clusters. When increasing the fluence up to 1016 cm-2, a buried amorphous layer forms, as indicated by e.g. Raman results where the Si-C bands become broader or even disappear. At a higher irradiation temperature of 670 K, amorphization is not observed at the same fluence, revealing a dynamic annealing process. However, results tend to suggest that the irradiated layer is highly heterogeneous and composed of different types of defects.

Chaâbane, N.; Debelle, A.; Sattonnay, G.; Trocellier, P.; Serruys, Y.; Thomé, L.; Zhang, Y.; Weber, W. J.; Meis, C.; Gosmain, L.; Boulle, A.

2012-09-01

372

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.

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

2013-01-01

373

The Mineralogy of Martian Dust: Design and Analysis Considerations for an X-Ray Diffraction/X-Ray Fluorescence (XRD/XRF) Instrument for Exobiological Studies  

NASA Technical Reports Server (NTRS)

A principal objective of Mars exploration is the search for evidence of past life which may have existed during an earlier clement period of Mars history. We would like to investigate the history of surface water activity (which is a requirement for all known forms of life) by identifying and documenting the distribution of minerals which require water for their formation or distribution. A knowledge of the mineralogy of the present Martian surface would help to identify areas which, due to the early activity of water, might have harbored ancient life. It would be desirable to establish the presence and characterize the distribution of hydrated minerals such as clays, and of minerals which are primarily of sedimentary origin such as carbonates, silica and evaporites. Mineralogy, which is more critical to exobiological exploration than is simple chemical analysis (absent the detection of organics), will remain unknown or will at best be imprecisely constrained unless a technique sensitive to mineral structure such as powder X-ray diffraction (XRD) is employed. Additional information is contained in the original extended abstract.

Blake, David; Vaniman, David; Bish, David; Morrison, David (Technical Monitor)

1994-01-01

374

Low-temperature synthesis of SrAl{sub 2}O{sub 4} by a modified sol-gel route: XRD and Raman characterization  

SciTech Connect

Among other alkaline-earth aluminates, the monoclinic (M) polymorph of SrAl{sub 2}O{sub 4} can be used as host material for Eu{sup 2+} luminescence based phosphors. With the aim of reducing the synthesis temperature of this polymorph, we have produced and characterized by XRD and Raman scattering solid solutions of the SrAl{sub 2-x}B{sub x}O{sub 4} system (x=<0.3) obtained by two different methods, a ceramic route and a modified sol-gel synthesis. Though the addition of boron lowers the temperature of obtention of the M polymorph in both type of samples, lower B contents are needed to stabilize the M form as single phase for samples prepared by the sol-gel method than through the ceramic route. In the sol-gel method, the M polymorph can be obtained at temperatures as low as 1200 deg. C, with a Boron content of just 1%. Rietveld profile analysis allows us to conclude that coexistence of the monoclinic and hexagonal polymorphs of SrAl{sub 2}O{sub 4} occurs for samples synthesized below an onset temperature of about 1000-1100 deg. C, that depends on the sample composition. Above those temperatures, only the monoclinic phase is formed.

Escribano, Purificacion [Departamento de Quimica Inorganica y Organica. Universitat Jaume I, 12071 Castellon (Spain); Marchal, Monica [Departamento de Quimica Inorganica y Organica. Universitat Jaume I, 12071 Castellon (Spain); Luisa Sanjuan, Maria [Instituto de Ciencia de Materiales de Aragon (Universidad de Zaragoza-CSIC), Facultad de Ciencias, 50009 Zaragoza (Spain); Alonso-Gutierrez, Pablo [Instituto de Ciencia de Materiales de Aragon (Universidad de Zaragoza-CSIC), Facultad de Ciencias, 50009 Zaragoza (Spain); Julian, Beatriz [Departamento de Quimica Inorganica y Organica. Universitat Jaume I, 12071 Castellon (Spain); Cordoncillo, Eloisa [Departamento de Quimica Inorganica y Organica. Universitat Jaume I, 12071 Castellon (Spain)]. E-mail: cordonci@qio.uji.es

2005-06-15

375

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

376

XAFS and XRD Study of the Atomic Displacements in Aurivillius Phase Ferroelectric Bi2.25Ca0.5Na0.25Nb2O9  

NASA Astrophysics Data System (ADS)

The novel layered perovskite-like oxide with Aurivillius phase structure Bi2.25Ca0.5Na0.25Nb2O9 has been synthesized by solid-state reaction method. This compound is a ferroelectric with the Curie temperature 972 K. The crystal structure of Bi2.25Ca0.5Na0.25Nb2O9 has been determined from powder diffraction data recorded at room temperature. The parameters of the orthorhombic cell (space group A21am) are: a=5.4845 Å, b=5.4549 Å, c=24.9195 Å. Using the profile of the X-ray diffraction pattern the atomic coordinates have been refined by Rietveld method and the Nb ion position in the oxygen octahedra has been found. It was shown that the Nb ion is displaced from the center of the oxygen octahedra by ~0.15 Å. Nb K-edge EXAFS spectra were measured over the temperature range 295 K - 960 K. The interatomic distances Nb-O and the mean-square relative displacements ?2 have been determined. The interatomic distances Nb-O at room temperature obtained from XAFS analysis are in a good agreement with those found from XRD data. It was revealed that the temperature increase results in the decreasing of Nb ion displacements from the center of the oxygen octahedra. However, in the vicinity of the ferroelectric phase transition the displacement of Nb ion was preserved.

Vlasenko, Valery G.; Shuvaev, Anatoliy T.; Pirog, Irina V.; Drannikov, Dmitriy; Zarubin, Ivan A.

2007-02-01

377

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

378

Magnetic properties of substituted strontium ferrite nanoparticles and thin films  

NASA Astrophysics Data System (ADS)

SrFe 12-x(Zr 0.5Mg 0.5) xO 19 nanoparticles and thin films with x=0-2.5 were synthesized by a sol-gel method on thermally oxidized silicon wafer (Si/SiO 2). Structural and magnetic characteristics of synthesized samples were studied employing x-rays diffraction (XRD), transmission electron microscopy (TEM), magnetic susceptometer, atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), and vibrating sample magnetometer (VSM). TEM micrographs display that the narrow size distribution of ferrite nanoparticles with average particle size of 50 nm were fabricated. Fitting obtained data of effective magnetic susceptibility by Vogel-Fulcher law confirms the existence of strong magnetic interaction among fine particles. XRD patterns and FE-SEM micrographs demonstrated that single phase c-axis hexagonal ferrite films with rather narrow grain size distribution were obtained. AFM micrographs exhibited that the surface roughness increases with an increase in Zr-Mg content. It was found from the VSM graphs that with an increase in substitution contents the coercivity decreases, while the saturation of magnetization increases. The Henkle plots confirms the existence of exchange coupling among nano-grain in ferrite thin films.

Ghasemi, Ali

2012-04-01

379

Comparison of two kinds of magnetic nanoparticles in vivo and in vitro.  

PubMed

This study compared a new type of polysaccharide-coated magnetic nanoparticles (in which the polysaccharide is derived from Angelica sinensis) with the dextran magnetic nanoparticles in terms of preparation, biocompatibility and tissue distribution in vivo and in vitro in order to examine the potential application of Angelica polysaccharide as a novel carrier in magnetic drug targeting (MDT). Magnetic nanoparticles were prepared by chemical co-precipitation. Their physical and chemical properties were determined by using the transmission electron microscope (TEM), laser particle size analyzer (DLS) and vibrating sample magnetometer (VSM), and their purity and structure by using X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR). The atomic absorption spectrometric method was performed for quantification of the iron content in different tissues. Histological sections were stained by Prussian blue staining to observe the disposition of magnetic nanoparticles in the liver and kidney. The results showed that both kinds of magnetic nanoparticles possessed small particle size, good dispersion and good magnetic properties. XRD showed the main component of the two magnetic nanoparticles was Fe(3)O(4) crystals, and FTIR proved Fe(3)O(4) was successfully coated by each polysaccharide, respectively. In vivo, Fe(3)O(4)-dextran accumulated in the liver, spleen and lung and Fe(3)O(4)-Angelica polysaccharide only in the spleen and lung. It was concluded that Angelica polysaccharide may be applied as a novel carrier in the preparation of magnetic nanoparticles. PMID:22684573

Wang, Liu; Zhang, Yu; Li, Shijun; Wang, Yujuan; Wang, Kaiping

2012-06-01

380

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 Fe 2+ and Fe 3+ 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 NaIO 4 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

381

Effects of uniformities of deposition of respirable particles on filters on determining their quartz contents by using the direct on-filter X-ray diffraction (DOF XRD) method.  

PubMed

In this study, field samplings were conducted in three workplaces of a foundry plant, including the molding, demolding, and bead blasting, respectively. Three respirable aerosol samplers (including a 25-mm aluminum cyclone, nylon cyclone, and IOSH cyclone) were used side-by-side to collect samples from each selected workplace. For each collected sample, the uniformity of the deposition of respirable dusts on the filter was measured and its free silica content was determined by both the DOF XRD method and NIOSH 7500 XRD method (i.e., the reference method). A same trend in measured uniformities can be found in all selected workplaces: 25-mm aluminum cyclone>nylon cyclone>IOSH cyclone. Even for samples collected by the sampler with the highest uniformity (i.e., 25-mm aluminum cyclone), the use of the DOF XRD method would lead to the measured free silica concentrations 1.15-2.89 times in magnitude higher than that of the reference method. A new filter holder should be developed with the minimum uniformity comparable to that of NIOSH 7500 XRD method (=0.78) in the future. The use of conversion factors for correcting quartz concentrations obtained from the DOF XRD method based on the measured uniformities could be suitable for the foundry industry at this stage. PMID:20006439

Chen, Ching-Hwa; Tsaia, Perng-Jy; Lai, Chane-Yu; Peng, Ya-Lian; Soo, Jhy-Charm; Chen, Cheng-Yao; Shih, Tung-Sheng

2010-04-15

382

Electrical and magnetic properties of chitosan-magnetite nanocomposites  

NASA Astrophysics Data System (ADS)

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

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

2010-04-01

383

Magnetic single-enzyme nanoparticles with high activity and stability  

SciTech Connect

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

Yang Zhengpeng [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Institute of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454000 (China); Si Shihui [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)], E-mail: sishihui@mail.csu.edu.cn; Zhang Chunjing [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Institute of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454000 (China)

2008-02-29

384

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

385

Structural transformation of vapor grown carbon nanofibers studied by HRTEM  

Microsoft Academic Search

Vapor grown carbon nanofibers have been extensively manufactured and investigated in recent years. In this study commercially\\u000a available vapor grown carbon nanofibers subjected to different processing and post processing conditions were studied employing\\u000a high resolution TEM images. The analysis showed that the fibers consist primarily of conical nanofibers, but can contain a\\u000a significant amount of bamboo nanofibers. Most conical nanofibers

Joseph G. Lawrence; Lesley M. Berhan; Arunan Nadarajah

2008-01-01

386

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

387

HRTEM imaging of atoms at sub-Angström resolution.  

PubMed

John Cowley and his group at Arizona State University pioneered the use of transmission electron microscopy for high-resolution imaging. Images were achieved three decades ago showing the crystal unit cell content at better than 4 A 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-Angström 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-Angström imaging, initially achieved by focal-series reconstruction of the specimen exit surface wave, will become commonplace for next-generation electron microscopes with C(S)-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 microscope 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. PMID:16123071

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

2005-06-01

388

Serpentinites from Central Cuba: petrology and HRTEM study  

Microsoft Academic Search

WehavesampledserpentinitesandthecloselyassociatedmetabasitesinthepaleosubductionzonecontextofCentralCuba in order to characterise the microstructures of serpentine minerals as a function of metamorphic grade. The samples were collected intheeclogiticunitoftheEscambrayMassifandintheZazaZone,whereeclogiticconditionswerelocallyattained.Serpentinitesare associated to the metabasites in lenses embedded in a metasediment matrix (Escambray) or form the matrix that embeds the metabasites(ZazaZone).Fieldandpetrologicalevidencesuggeststhatserpentinitesandassociatedmetabasitesunderwentthesame metamorphic history.Serpentinites from the Escambray Massif havepreserved high-grade structures. In theZaza Zone, most of the sampled serpentinites only underwent

Anne-Line Auzende; Bertrand Devouard; Stéphane Guillot; Isabelle Daniel; Alain Baronnet; Jean-Marc Lardeaux

2002-01-01

389

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

390

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

391

Sinus Excision, Release of Coccycutaneous Attachments and Dermal-Subcuticular Closure (XRD Procedure): A Novel Technique in Flattening the Natal Cleft in Pilonidal Sinus Treatment  

PubMed Central

INTRODUCTION The objective of this study was to analyse, prospectively, the outcome of a new technique – excision of pilonidal sinus and flattening the natal cleft by division of the coccycutaneous attachments at the lower end of the incision. PATIENTS AND METHODS Sixty-six consecutive patients with chronic pilonidal sinuses were treated between 1995 and 2001. The procedure consisted of an elliptical, wide, local excision, release of the coccycutaneous attachments and primary closure using dermal-subcuticular closure (XRD). Suction drains were used until drainage was minimal. The height of skin level at the lower angle of the wound from the coccyx was measured intra-operatively before and after division of the coccycutaneous attachments. Postoperatively, patients were assessed for hospital stay, return to normal activity, complications and recurrence. RESULTS Sixty-four patients (97%) were males, median age 27 years. The height of skin level rose from a mean of 1.8 cm (95% CI, 1.78–1.85) to a mean of 3.8 cm (95% CI, 3.77–3.88; P < 0.001). Morbidity affected 12 patients (18%), epidermal separation of the lower wound angles (6 patients), seromas (5 patients) and 1 wound dehiscence at 2 weeks. All other wounds healed primarily without dehiscence. There were no recurrences after a median follow-up of 22.5 months (range, 12–38 months). CONCLUSIONS Release of the coccycutaneous attachments is an easy technique to learn, which seems to be an effective way of flattening the natal cleft and may result in lower recurrence rate. This technique should be tried in uncomplicated pilonidal sinus disease before more complex procedures are attempted.

Marzouk, Deya M; Abou-Zeid, Ahmed A; Antoniou, Anthony; Haji, Amyn; Benziger, H

2008-01-01

392

Anion and cation distributions in Fe(II-III) hydroxysalt green rusts from XRD and Mössbauer analysis (carbonate, chloride, sulphate, …); the "fougerite" mineral  

NASA Astrophysics Data System (ADS)

Main crystallographic features of Fe(II-III) hydroxysalts usually named green rusts are known from XRD. However, Mössbauer spectroscopy often used to characterise them revealed that several Fe(II) sites exist that have not been elucidated yet. The structure is classified in green rust one, GR1, and green rust two, GR2, according to the sequence of stacking of Fe(OH) 2 brucite-like layers that depends on the shape and type of anions inserted within interlayers. A long-range order had been determined by Rietveld analysis for the hydroxysulphate GR2(SO 42-), that correspond to the distribution of cations and anions. Using similar interactions in the GR1 structure where long-range ordering is not observed, it is possible to devise models of correlated anion and cation distributions that link layers along the 3¯ axis. The predicted abundance of Fe(II) environments permits to attribute all hyperfine components. Anion distribution within interlayers for GR1(Cl -) and GR1(CO 32-) explains that the composition lies around [Fe II3Fe III(OH) 8] +•[Cl, ˜2H 2O] - for the first one whereas a domain around [Fe II4Fe III2(OH) 12] 2+•[CO 32-, ˜3H 2O] 2- exists for the second one. "Fougerite" mineral (IMA 2003-057) is [(Fe II, Mg II) (1- x) (Fe III, Al III) x(OH) 2] x+ •[( x/2) CO 32-, yH 2O] x- , where (˜1/4)? x?(1/3) and y?[1-(3/2) x]. Poles are pyroaurite [Mg II6Fe III2(OH) 16] 2+•[CO 32-• ˜ 4H 2O] 2- and hydrotalcite [Mg II4Al III2(OH) 12] 2+•[CO 32-• ˜ 3H 2O] 2-.

Génin, Jean-Marie R.; Ruby, Christian

2004-07-01

393

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

394

Crystallization of glasses in the system SiO 2 Li 2 O-TiO 2 Al 2 O 3 , investigated in situ at high temperature by XRD and DTA methods  

Microsoft Academic Search

The processes of crystallization of fibres (diameter 10–15?m) and coarse powders (grain size 500–1000?m) with four compositions in the system SiO2-Li2O-TiO2-Al2O3 were studied by conventional and in situ high-temperature XRD, DTA, SEM and optical microscopy. Activation energies of crystallization and morphological indices were deduced from the kinetic curves obtained by recording the high-temperature XRD peak intensity as a function of

A. Benedetti; G. Fagherazzi; S. Meriani; G. Sorarù

1984-01-01

395

Structural and magnetic properties of nanocrystalline nickel-rich Fe-Ni alloy powders prepared via hydrazine reduction  

NASA Astrophysics Data System (ADS)

Nickel-rich Fe-Ni alloy nanoparticles with different compositions were prepared by solution reduction using hydrazine as reductant. The phase composition, morphologies and magnetic properties of as-prepared and annealed samples were characterized by an X-ray diffractionmeter (XRD), a scanning electron microscope (SEM) and a vibrating sample magnetometer (VSM), respectively. XRD results show that all the samples exhibit a single phase with face-centered cubic structure before and after annealing. SEM images show that the as-prepared spherical particles are composed of smaller crystallites. VSM results indicate that the saturation magnetization decreases obviously with the increase of nickel content, while it increases with the annealing temperature. In addition, the samples transform from a half hard magnetic behavior to a typical soft magnetic behavior with the increase of annealing temperature.

Xu, Zhichao; Jin, Chuangui; Xia, Ailin; Zhang, Junyan; Zhu, Guohui

2013-06-01

396

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

397

Magnetic Reconnection  

NASA Video Gallery

This science visualization shows a magnetospheric substorm, during which, magnetic reconnection causes energy to be rapidly released along the field lines in the magnetotail, that part of the magne...

398

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

399

Magnetic coupling in Co1-xPtx (x>0.5) nanowires electrodeposited on an AAO template  

Microsoft Academic Search

Thirty nanometer diameter Co Pt nanowires of different composition were fabricated by electrodepositing the Co and Pt atoms to nanoporous anodized aluminium oxide (AAO) templates. The structure and magnetic properties are studied by transmission electron microscopy (TEM), induction-coupled plasma spectrometer (ICP), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The as deposited nanowires with Pt content about 50 at.% present

W. Chen; Z. Li; G. B. Ji; S. L. Tang; M. Lu; Y. W. Du

2005-01-01

400

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...

401

Magnetic silica nanotubes: synthesis, drug release, and feasibility for magnetic hyperthermia.  

PubMed

A new kind of silica nanotube with incorporated ?-Fe(2)O(3) nanoparticles has been successfully prepared through sol-gel processes. Hematite particles supported on carbon nanotubes served as templates for the fabrication of the magnetic silica nanotubes. The obtained nanostructures consisting of magnetic Fe(2)O(3) nanoparticles protected by a silica shell were fully characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), N(2) sorption and desorption, and magnetization studies. The hollow inner space and the magnetic functionalization render the material promising for applications in biology and medicine. This is underlined by studies in alternating magnetic fields which show a significant heating effect, i.e., the feasibility for applications in hyperthermia therapies. In addition, the material exhibits enhanced drug-loading capacity which is demonstrated by loading with rhodamine B molecules as drugs and corresponding release experiments. The results show that magnetic silica nanotubes can be straightforwardly synthesized and have a great potential as a multifunctional drug carrier system. PMID:22486255

Chen, Xuecheng; Klingeler, Rüdiger; Kath, Matthias; El Gendy, Ahmed A; Cendrowski, Krzysztof; Kalenczuk, Ryszard J; Borowiak-Palen, Ewa

2012-04-01

402

Magnetic imaging method based on magnetic relaxation of magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

We present a well-posed magnetic imaging method based on magnetic relaxation of magnetic nanoparticles for obtaining high-spatial resolution image of magnetic tracers. The method relies on the principle that Néel relaxation of the magnetic nanoparticles is faster in a finite magnetic field than in the absence of the field. The magnetic nanoparticles are used as signal generator and a superconducting quantum interference device is used as the signal detector. An image of superparamagnetic iron oxide nanoparticle tracer is obtained directly by mapping the magnetization decays. The experimental imaging capability is demonstrated using commercially available gamma-ferric oxide (?-Fe2O3) magnetic nanoparticles.

Sarangi, S.; Tan, I. C.; Brazdeikis, A.

2009-05-01

403

MAGNETIC IMAGING OF NANOCOMPOSITE MAGNETS  

SciTech Connect

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

VOLKOV,V.V.ZHU,Y.

2003-08-03

404

Study of the effect of prolonged magnetic stirring on the physico-chemical surface properties of nanometric transition alumina  

Microsoft Academic Search

This article reports the study of a transition nanometric alumina both as such and after prolonged magnetic stirring in bi-distilled\\u000a water. Stirring was effective in inducing a significant reduction of starting particles agglomeration and modification of\\u000a the surface properties of the material. The formation of an Al(OH)3 (gibbsite) phase after magnetic stirring in water was detected by means of XRD

B. Bonelli; P. Palmero; F. Lomello; M. Armandi; M. Lombardi

2010-01-01

405

Role of Ni(NO 3) 2 in the preparation of a magnetic coal-based activated carbon  

Microsoft Academic Search

The role of Ni(NO3)2 in the preparation of a magnetic activated carbon is reported in this paper. Magnetic coal-based activated carbons (MCAC) were prepared from Taixi anthracite with low ash content in the presence of Ni(NO3)2. The MCAC materials were characterized by a vibrating sample magnetometer (VSM), X-ray diffraction (XRD), a scanning electric microscope (SEM), and by N2 adsorption. The

Jun Zhang; Qiang Xie; Juan Liu; Mingshun Yang; Xing Yao

2011-01-01

406

Multifunction Gd2O3:Eu nanocrystals produced by solution combustion synthesis: Structural, luminescent, and magnetic characterization  

Microsoft Academic Search

The synthesis, structural, luminescent, and magnetic properties of multifunction 8 at. % Eu-doped Gd2O3 nanocrystals were investigated. The material was synthesized by the solution combustion technique and characterized by x-ray diffraction (XRD), transmission electron microscopy, and photoluminescence and magnetization measurements. The as-prepared material presents predominant base-centered monoclinic structure with average crystallite size of 35 nm. Isothermal annealing at 1000 °C

L. G. Jacobsohn; B. L. Bennett; R. E. Muenchausen; S. C. Tornga; J. D. Thompson; O. Ugurlu; D. W. Cooke; A. L. Lima Sharma

2008-01-01

407

Effect of Cr Substitution on Thermal Stability of Magnetization and Oxidation Resistance of SmFeN Compounds  

Microsoft Academic Search

We investigated the effects of Cr element substitution on thermal stability of magnetic flux and oxidation resistance of SmFeN compounds by X-ray diffraction (XRD), thermogravimetry analysis (TG), and flux aging loss measurement methods. We found that with increases in Cr substitution, the irreversible flux losses of bonded magnets made from these alloys decrease remarkably. When Cr substitution reaches 2 at%,

Jinwen Ye; Ying Liu; Xianfu Chen; Mingjing Tu

2008-01-01

408

Highly accessible catalytic sites on recyclable organosilane-functionalized magnetic nanoparticles: An alternative to functionalized porous silica catalysts  

Microsoft Academic Search

Diaminosilane-functionalized cobalt spinel ferrite (CoFe2O4) magnetic nanoparticles are synthesized and used as efficient heterogeneous base catalysts for the Knoevenagel condensation of aromatic and heteroaromatic aldehydes with malononitrile. The magnetic nanoparticle catalyst is characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), and nitrogen physisorption measurements. Quantitative conversion of the reactants is achieved

Nam T. S. Phan; Christopher W. Jones

2006-01-01

409

Magnetic comparison of abiogenic and biogenic alteration products of lepidocrocite  

NASA Astrophysics Data System (ADS)

Lepidocrocite is a potentially important Fe-bearing precursor phase for the production of nanoscale Fe-oxide particles in the environment. We present a detailed magnetic characterization of various alteration products of lepidocrocite resulting from thermal dehydroxylation reactions and bacterially induced bioreduction and remineralization, accompanied by characterization with x-ray diffraction (XRD) and transmission electron microscopy. Dehydroxylation during annealing at moderate temperatures produces a topotactic transformation from lepidocrocite to maghemite when heated in an oxidizing atmosphere, or to magnetite when heated in a reducing atmosphere. The abiotic Fe-oxide products form an oriented framework of strongly interacting superparamagnetic crystallites and are characterized by a distinctive porous nanostructure observed by electron microscopy. Lepidocrocite bioreduction by the iron-reducing bacterium Shewanella putrefaciens ATCC 8071 produces nanoscale particles of a strongly magnetic phase. This Fe(II)-bearing mineral produced by bioreduction is highly crystalline and euhedral in shape, with a broad grain size distribution and is indicated by magnetic and XRD measurements to be a cation-excess magnetite. We highlight the distinguishing microscopic characteristics of magnetite from both abiotic and bacterially induced mineralization that should allow them to be identified in natural settings. Moreover, both mechanisms of alteration represent potential pathways for the direct formation of strongly magnetic fine-grained Fe-oxide particles in sedimentary environments.

Till, J. L.; Guyodo, Y.; Lagroix, F.; Ona-Nguema, G.; Brest, J.

2014-06-01

410

Magnetic properties of Nd-Ga-Febal-Nb-B alloy  

NASA Astrophysics Data System (ADS)

Here, we have synthesized Nd-Ga-Febal-Nb-B alloy by strip casting method. The crystalline and magnetic properties of sample were investigated with x-ray diffractometer (XRD), vibrating sample magnetometer (VSM), and Mössbauer spectrometer. The XRD pattern was analyzed with the Rietveld refinement method, indicating a tetragonal structure and the space group of P42/mnm. The temperature dependence of zero-field cooled (ZFC) magnetization curve was measured under applied field at temperature ranging from 4.2 to 740 K. From the ZFC curve, Curie temperature and spin reorientation temperature are determined to be 615 K and 130 K, respectively. Also, Mössbauer spectra were measured at various temperatures ranging from 4.2 to 620 K. Each spectrum was fitted with 6-sextets for Fe site (8j1, 8j2, 16k1, 16k2, 4c, and 4e), and magnetic hyperfine field, Isomer shift, electric quadrupole shift, and area ratio values were obtained from the fit. We observed the change in slope of magnetic hyperfine field and electric quadrupole shift at 130 K while the Curie temperature was determined to be 615 K from the measurement of zero velocity counter, agreeing with the values obtained from VSM measurements.

Kim, Hyunkyu; Yong An, Sung; Ryong Choi, Kang; Choi, Moonhee; Sung Kim, Chul

2014-05-01

411

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

412

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.

413

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

414

Magnetic Bubbles  

NASA Astrophysics Data System (ADS)

Bubbles in liquids driven by a sound field are used in many disciplines: for example bubbles clean surfaces in ultrasonic water bathes, they catalyze unique chemical reactions in sonochemistry, and under special conditions even create light. However, conventional bubbles have a major limitation when placed in an acoustic field: it is extremely hard to control their position. Here we present a new type of bubble that has permanent magnetization originating from a shell of self-assembled nanoparticles, so that magnetic fields can be used to control the bubble's position independently. We will report on the recipe and the experiment to study bubble oscillations in weak magnetic fields. The magnetic susceptibility of the bubbles is proportional to their surface area,?=(9±3x10-6m)r^2, where r is the radius. Also they are compressible in moderate acoustic fields and induce a microstreaming flow with a toroidal vortex at the upper pole of the bubble. Similar microstreaming flows have been used to transport and rupture cells at small scales. Thus we envision applications in manipulation of biological materials and in microfluidic devices using acoustic and magnetic forces.

Zhao, Xue; Quinto-Su, Pedro; Ohl, Claus-Dieter

2008-11-01

415

Magnets Enter the Picture  

NSDL National Science Digital Library

This book began with the basics of electricity, and now it's time to introduce the basics of magnetism. What better way to do that than to play around with magnets? In this chapter, by playing with magnets, you'll learn about the types of magnets, magnetic materials, the properties of magnets, and how the Earth creates its own magnetic field.

Robertson, William C.

2005-01-01

416

Mapping Magnetic Influence  

NSDL National Science Digital Library

This educatorâs guide details activities that allow students to explore magnets and the region of influence around a magnet called a magnetic field. Students learn that magnets exert a force on a magnetically-sensitive object without coming into direct contact with it. Students then create a map of the magnetic influence around the magnet.

2005-02-01

417

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.

418

Synthesis of magnetic nanofibers using femtosecond laser material processing in air  

PubMed Central

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

2011-01-01

419

A silicon dioxide modified magnetic nanoparticles-labeled lateral flow strips for HBs antigen.  

PubMed

Herein we reported a new type of silicon dioxide wrapped magnetic nanoparticles-labeled lateral flow strip for detection of HBs antigen in sera. The SiO2 wrapped Fe3O4 nanocomposites were prepared and characterized by HR-TEM, FTIR and magnetometer. As-prepared nanocomposites were used to label anti-HBV surface monoclonal antibody, the lateral flow strips were constructed, and 100 specimens of sera were collected and tested. Results showed that the prepared SiO2 wrapped Fe3O4 nanocomposites were shell/core structure, well dispersed, with the size of 25 nm in diameter, the thickness of the shell was about 3 nm, their magnetic saturation intensity was 44.3 meu g(-1). Clinical sera specimens test results showed that the prepared lateral flow strips were with the detection limitation of 5 pg/mL by naked eye observation, and 0.1 pg/mL by CCD reader or MAR Analyzer, specificity was 100%. In conclusion, one kind of silicon dioxide wrapped magnetic nanoparticles-labeled lateral flow strip for ultrasensitive detection of HBs antigen was successfully developed, its ease of use, sensitiveness and low-cost make it well-suited for population-based on-the-site hepatitis B screening. PMID:22416576

Zhang, Xueqing; Jiang, Lin; Zhang, Chunlei; Li, Ding; Wang, Can; Gao, Feng; Cui, Daxiang

2011-12-01

420

Planetary Magnetism  

NSDL National Science Digital Library

Until the middle of the 20th century, the Earth's magnetism seemed to be a happy accident of nature. Too many factors had to fit just right, the fluid core of the Earth, its electrical conductivity and its motions, all had to satisfy the strict requirements of dynamo theory. That was before other planets in the solar system were visited and examined. Now we know that among those planets, only Venus lacks any magnetism. The planets differ greatly in size and properties, and their fields differ, too. Yet they all seem to have dynamo fields, or (in the case of Mars and the Moon) have had them in the past. This site reviews the discovery of the magnetism of other planets and discusses their eccentricities.

Stern, David

421

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.

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

2012-01-01

422

Magnetic shielding for magnetically levitated vehicles  

Microsoft Academic Search

The magnetic shielding required for magnetically levitated vehicles is discussed. Shielding is needed to protect passengers in a vehicle from stray dc magnetic fields coming from the superconducting dipoles carried by the vehicle. In addition, the superconducting dipoles must be shielded against various ac magnetic fields. Here we consider shielding of ac magnetic fields generated by the propulsion windings for

YUKIKAZU IWASA; Francis Bitter

1973-01-01

423

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

424

Magnetic Variations  

NSDL National Science Digital Library

In this activity students analyze tabulated data and convert it into a graph, search for patterns and trends, and make a prediction about future events. They discover that a graphical display of numbers may help to show patterns such as trends or varying rates of change and that such patterns sometimes can be used to make predictions about the phenomenon being graphed. This activity places the changes in Earth's magnetic field in an historical context that attemps to correct many misconceptions about Earth's magnetic field and debunk a 2003 movie that depicted dire consequences due to pole reversal.

Odenwald, Sten

425

Magnetic particles  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

426

Synthesis, characterization, magnetic and electrical properties of the novel conductive and magnetic Polyaniline\\/MgFe 2O 4 nanocomposite having the core–shell structure  

Microsoft Academic Search

Conductive and magnetic Polyaniline\\/MgFe2O4 nanocomposite was successfully synthesized in the form of core–shell via in situ chemical polymerization of aniline in the presence of MgFe2O4 nano-particles. X-ray powder diffraction of ferrites indicated that the structure of the core material is having the spinel structure, and demonstrated the formation of PAni\\/MgFe2O4 nanocomposite. XRD and TEM photographs showed that the particle's size

Rasha M. Khafagy

2011-01-01

427

Magnetic properties of hydrogen-included TiZrNiPd quasicrystals.  

PubMed

Quasicrystals prepared by rapid quenching of Pd-added TiZrNi ingots were hydrogenated, and effects of hydrogen for magnetic properties were compared with the unhydrogenated ones under magnetic fields from -10000 to 10000 Oe. The magnetization values obtained from vibrating sample magnetometer (VSM) were analyzed with the combination of powder X-ray diffraction (XRD) data. While its contribution is larger than that of Pd, hydrogen decreases the magnetic moments of both Pd-doped and undoped quasicrystals. As increasing the amount of absorbed hydrogen which is represented by H/M (hydrogen to host metal atom ratio) values from 0 to 1.19, the magnetization values of Ti53Zr27Ni20 quasicrystals measured at 10000 Oe significantly decreased from 0.301 to 0.212 emu/g. A careful analysis of XRD data demonstrated that the reduced interactions of magnetic dipole moments between Ni atoms, as the product of the expansion of the quasilattice constants after hydrogenation, are responsible for the decreased magnetization values in hydrogenated TiZrNiPd quasicrystal samples. PMID:22966713

Shin, Hongsik; Lee, Sang-Hwa; Jo, Youngsoo; Kim, Jae-Yong

2012-07-01

428

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