CO{sub 2} capture in Mg oxides doped with Fe and Ni; Captura de CO{sub 2} en oxidos de Mg dopados con Fe y Ni

Energy Technology Data Exchange (ETDEWEB)

Sanchez S, I. F.

2016-07-01

In this work the CO{sub 2} capture-desorption characteristics in Mg oxides doped with Fe and Ni obtained by the direct oxidation of Mg-Ni and Mg-Fe mixtures are presented. Mixtures of Mg-Ni and Mg-Fe in a different composition were obtained by mechanical milling in a Spex-type mill in a controlled atmosphere of ultra high purity argon at a weight / weight ratio of 4:1 powder using methanol as a lubricating agent, for 20 h. The powders obtained by mechanical milling showed as main phase, the Mg with nanocrystalline structure. Subsequently, the mixtures of Mg-Ni and Mg-Fe were oxidized within a muffle for 10 min at 600 degrees Celsius. By means of X-ray diffraction analysis, the Mg O with nano metric grain size was identified as the main phase, which was determined by the Scherrer equation. In the Mg O doped with Ni, was identified that as the Ni amount 1 to 5% by weight dispersed in the Mg O matrix was increased, the main peak intensity of the Ni phase increased, whereas in the Mg O doped with Fe was observed by XRD, that the Fe{sub 2}O{sub 3} phase was present and by increasing the amount of Fe (1 to 5% by weight) dispersed in the crystalline phase of Mg O, the intensity of this impurity also increased. Sem-EDS analysis showed that the Ni and Fe particles are dispersed homogeneously in the Mg O matrix, and the particles are porous, forming agglomerates. Through energy dispersive spectroscopy analysis, the elemental chemical composition obtained is very close to the theoretical composition. The capture of CO{sub 2} in the Mg O-1% Ni was carried out in a Parr reactor at different conditions of pressure, temperature and reaction time. Was determined that under the pressure of 0.2 MPa at 26 degrees Celsius for 1 h of reaction, the highest CO{sub 2} capture of 7.04% by weight was obtained, while in Mg O-1% Fe the CO{sub 2} capture was 6.32% by weight. The other magnesium oxides doped in 2.5 and 5% by weight Ni and Fe showed lower CO{sub 2} capture. The different stages

Epitaxial growth of bcc-Fe{sub x}Co{sub 100-x} thin films on MgO(1 1 0) single-crystal substrates

Energy Technology Data Exchange (ETDEWEB)

Ohtake, Mitsuru, E-mail: ohtake@futamoto.elect.chuo-u.ac.j [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Nishiyama, Tsutomu; Shikada, Kouhei [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Kirino, Fumiyoshi [Graduate School of Fine Arts, Tokyo National University of Fine Arts and Music, 12-8 Ueno-koen, Taito-ku, Tokyo 110-8714 (Japan); Futamoto, Masaaki [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan)

2010-07-15

Fe{sub x}Co{sub 100-x} (x=100, 65, 50 at%) epitaxial thin films were prepared on MgO(1 1 0) single-crystal substrates heated at 300 deg. C by ultra-high vacuum molecular beam epitaxy. The film structure and the growth mechanism are discussed. FeCo(2 1 1) films with bcc structure grow epitaxially on MgO(1 1 0) substrates with two types of variants whose orientations are rotated around the film normal by 180 deg. each other for all compositions. Fe{sub x}Co{sub 100-x} film growth follows the Volmer Weber mode. X-ray diffraction analysis indicates the out-of-plane and the in-plane lattice spacings are in agreement with the values of respective bulk Fe{sub x}Co{sub 100-x} crystals with very small errors less than +-0.4%, suggesting the strains in the films are very small. High-resolution cross-sectional transmission electron microscopy shows that periodical misfit dislocations are preferentially introduced in the film at the Fe{sub 50}Co{sub 50}/MgO interface along the MgO[1 1-bar 0] direction. The presence of such periodical dislocations decreases the large lattice mismatch of about -17% existing at the FeCo/MgO interface along the MgO[1 1-bar 0] direction.

Mg1-xZnxFe2O4 nanoparticles: Interplay between cation distribution and magnetic properties

Directory of Open Access Journals (Sweden)

S. Raghuvanshi

2018-04-01

Full Text Available Correlation between cationic distribution, magnetic properties of Mg1-xZnxFe2O4 (0.0 ≤ x ≤ 1.0 ferrite is demonstrated, hardly shown in literature. X-ray diffraction (XRD confirms the formation of cubic spinel nano ferrites with grain diameter between 40.8 to 55.4 nm. Energy dispersive spectroscopy (EDS confirms close agreement of Mg/Fe, Zn/Fe molar ratio, presence of all elements (Mg, Zn, Fe, O, formation of estimated ferrite composition. Zn addition (for Mg shows: i linear increase of lattice parameter aexp, accounted for replacement of an ion with higher ionic radius (Zn > Mg; ii presence of higher population of Fe3+ ions on B site, and unusual occurrence of Zn, Mg on A and B site leads to non-equilibrium cation distribution where we observe inverse to mixed structure, and is in contrast to reported literature where inverse to normal transition is reported; iii effect on A-A, A-B, B-B exchange interactions, affecting coercivity Hc, Ms. A new empirical relation is also obtained showing linear relation between saturation magnetization Ms – inversion parameter δ, oxygen parameter u4¯3m. Non-zero Y-K angle (αYK values implies Y-K type magnetic ordering in the studied samples.

Comparing the Electrochemical Performance of LiFePO4/C Modified by Mg Doping and MgO Coating

Directory of Open Access Journals (Sweden)

Jianjun Song

2013-01-01

Full Text Available Supervalent cation doping and metal oxide coating are the most efficacious and popular methods to optimize the property of LiFePO4 lithium battery material. Mg-doped and MgO-coated LiFePO4/C were synthesized to analyze their individual influence on the electrochemical performance of active material. The specific capacity and rate capability of LiFePO4/C are improved by both MgO coating and Mg doping, especially the Mg-doped sample—Li0.985Mg0.015FePO4/C, whose discharge capacity is up to 163 mAh g−1, 145.5 mAh g−1, 128.3 mAh g−1, and 103.7 mAh g−1 at 1 C, 2 C, 5 C, and 10 C, respectively. The cyclic life of electrode is obviously increased by MgO surface modification, and the discharge capacity retention rate of sample LiFePO4/C-MgO2.5 is up to 104.2% after 100 cycles. Comparing samples modified by these two methods, Mg doping is more prominent on prompting the capacity and rate capability of LiFePO4, while MgO coating is superior in terms of improving cyclic performance.

CO_2 capture in Mg oxides doped with Fe and Ni

International Nuclear Information System (INIS)

Sanchez S, I. F.

2016-01-01

In this work the CO_2 capture-desorption characteristics in Mg oxides doped with Fe and Ni obtained by the direct oxidation of Mg-Ni and Mg-Fe mixtures are presented. Mixtures of Mg-Ni and Mg-Fe in a different composition were obtained by mechanical milling in a Spex-type mill in a controlled atmosphere of ultra high purity argon at a weight / weight ratio of 4:1 powder using methanol as a lubricating agent, for 20 h. The powders obtained by mechanical milling showed as main phase, the Mg with nanocrystalline structure. Subsequently, the mixtures of Mg-Ni and Mg-Fe were oxidized within a muffle for 10 min at 600 degrees Celsius. By means of X-ray diffraction analysis, the Mg O with nano metric grain size was identified as the main phase, which was determined by the Scherrer equation. In the Mg O doped with Ni, was identified that as the Ni amount 1 to 5% by weight dispersed in the Mg O matrix was increased, the main peak intensity of the Ni phase increased, whereas in the Mg O doped with Fe was observed by XRD, that the Fe_2O_3 phase was present and by increasing the amount of Fe (1 to 5% by weight) dispersed in the crystalline phase of Mg O, the intensity of this impurity also increased. Sem-EDS analysis showed that the Ni and Fe particles are dispersed homogeneously in the Mg O matrix, and the particles are porous, forming agglomerates. Through energy dispersive spectroscopy analysis, the elemental chemical composition obtained is very close to the theoretical composition. The capture of CO_2 in the Mg O-1% Ni was carried out in a Parr reactor at different conditions of pressure, temperature and reaction time. Was determined that under the pressure of 0.2 MPa at 26 degrees Celsius for 1 h of reaction, the highest CO_2 capture of 7.04% by weight was obtained, while in Mg O-1% Fe the CO_2 capture was 6.32% by weight. The other magnesium oxides doped in 2.5 and 5% by weight Ni and Fe showed lower CO_2 capture. The different stages of mass loss and thermal

Ab-initio study of the interfacial properties in ultrathin MgO films on O-rich FeO/Fe(001) surfaces

Energy Technology Data Exchange (ETDEWEB)

Jeon, Junjin; Yu, Byungdeok [University of Seoul, Seoul (Korea, Republic of)

2014-09-15

Using ab-initio simulations based on density functional theory, we systematically studied the interfacial properties of MgO films on O-rich FeO/Fe(001) surfaces with increasing number of MgO layers from one to three monolayers (MLs). The structural and the adhesion properties of the MgO/FeO/Fe(001) system were assessed and compared with those of simple MgO/Fe(001) interfaces. Our calculated results showed that the adhesion energy for MgO/FeO/Fe(001) was smaller than that for simple MgO/Fe(001). An analysis of the electronic structures and the charge rearrangements of the MgO/FeO/Fe(001) interfaces was also performed. The work functions of the MgO/FeO/Fe(001) systems upon the deposition of MgO films exhibited smaller decreases (0.45 - 0.67 eV) than those (1.43 - 1.74 eV) of the MgO/Fe(001) systems. In addition, the obtained work functions (3.77 - 3.99 eV) for MgO/FeO/Fe(001) were much larger than those (2.12 - 2.43 eV) for MgO/Fe(001).

Interlayer exchange coupling, dipolar coupling and magnetoresistance in Fe/MgO/Fe trilayers with a subnanometer MgO barrier

Energy Technology Data Exchange (ETDEWEB)

Kozioł-Rachwał, A. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); Skowroński, W.; Frankowski, M. [AGH University of Science and Technology, Department of Electronics, al. Mickiewicza 30, 30-059 Kraków (Poland); Chęciński, J. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); AGH University of Science and Technology, Department of Electronics, al. Mickiewicza 30, 30-059 Kraków (Poland); Ziętek, S.; Rzeszut, P. [AGH University of Science and Technology, Department of Electronics, al. Mickiewicza 30, 30-059 Kraków (Poland); Ślęzak, M.; Matlak, K.; Ślęzak, T. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); Stobiecki, T. [AGH University of Science and Technology, Department of Electronics, al. Mickiewicza 30, 30-059 Kraków (Poland); Korecki, J. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Kraków (Poland)

2017-02-15

Fe/MgO/Fe trilayers with a subnanometer MgO tunnel barrier were grown by molecular beam epitaxy. Longitudinal magnetooptic Kerr effect measurements confirmed the existence of the antiferromagnetic interlayer exchange coupling (IEC) between the Fe layers for 2 ÅMgO}<6 Å. The coupling was enhanced for the trilayer grown on a homoepitaxial MgO buffer layer, and its IEC constant was estimated to be −3.3 erg/cm{sup 2} at a MgO thickness of 2.7 Å. After magnetic characterization, the sample was patterned into circular-shaped pillars with diameters ranging from 200 nm to 520 nm. We showed that the dipolar coupling that appeared after the nanofabrication process modified the effective coupling between layers, and we determined dependence of the dipolar coupling on the pillar diameter. Finally, magnetoresistance (MR) was measured as a function of MgO thickness (d{sub MgO}), and a non-zero MR was found for the MgO as thin as 3.4 Å. Extrapolation of the MR (d{sub MgO}) dependence to MR=0 allowed us to determine the length of the pinholes in our sample, which was estimated to be (3.2±0.5) Å. - Highlights: • Strong antiferromagnetic (AFM) interlayer exchange coupling (IEC) between Fe layers in Fe/MgO/Fe. • After nanofabrication the effective AFM IEC is enhanced due to the dipolar coupling. • The dipolar coupling that appeared after the nanofabrication process modified the effective coupling between layers. • Non-zero magnetoresistance values registered for the Fe/MgO/Fe trilayers with the MgO spacers as thin as 3.4 Å.

Enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers by inhibiting Ta diffusion

Energy Technology Data Exchange (ETDEWEB)

Li, Xu-Jing; Jiang, Shao-Long; Zhang, Jing-Yan; Liu, Qian-Qian; Liu, Yi-Wei; Zhao, Jian-Cheng [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Wu, Zheng-Long [Analytical and Testing Center, Beijing Normal University, Beijing 100875 (China); Feng, Chun, E-mail: fengchun@ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Li, Ming-Hua [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Yu, Guang-Hua, E-mail: ghyu@mater.ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China)

2016-03-01

Graphical abstract: To reveal the underlying mechanism of Mg influence on the enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers, the X-ray photoelectron spectroscopy analysis have been performed. It is found that a certain amount of Mg interlayer at the CoFeB/MgO interface could prevent the Ta oxidation to some extent due to the oxygen deficit MgO{sub x} (x < 1), and consequently lower the diffusion motivation of Ta from the bottom layer to the CoFeB/MgO interfaces to some extent during the annealing process. The prevention of Ta diffusion realizes the effective hybridization of Fe and O at the CoFeB/MgO interface and maintains interfacial magnetic anisotropy (K{sub CoFeB/MgO}). As a result, the perpendicular magnetic anisotropy at high annealing temperatures was maintained. - Highlights: • High annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers was realized. • X-ray photoelectron spectroscopy analysis has been performed to explore the reasons. • The prevention of Ta diffusion was realized by introducing Mg at the CoFeB/MgO interface. - Abstracts: To reveal the underlying mechanism of Mg influence on the enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers, the X-ray photoelectron spectroscopy analysis has been performed. It is found that a certain amount of Mg interlayer at the CoFeB/MgO interface could prevent the Ta oxidation, and consequently lower the diffusion motivation of Ta from the bottom layer to the CoFeB/MgO interfaces to some extent in the annealing process. The prevention of Ta diffusion realizes the effective hybridization of Fe and O at the CoFeB/MgO interface and maintains interfacial magnetic anisotropy (KCoFeB/MgO). As a result, the perpendicular magnetic anisotropy at high annealing temperatures is maintained.

Shape anisotropy and hybridization enhanced magnetization in nanowires of Fe/MgO/Fe encapsulated in carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Aryee, Dennis [Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground, MD 21005 (United States); Department of Physics and Engineering Physics, Morgan State University, Baltimore, MD 21251 (United States); Seifu, Dereje, E-mail: dereje.seifu@morgan.edu [Department of Physics and Engineering Physics, Morgan State University, Baltimore, MD 21251 (United States)

2017-05-01

Arrays of tunneling magnetoresistance (TMR) nanowires were synthesized for the first time by filling Fe/MgO/Fe inside vertically grown and substrate supported carbon nanotubes. The magnetic properties of nanowires and planar nanoscale thin films of Fe/MgO/Fe showed several similarities, such as two-fold magnetic symmetry and ratio of orbital moment to spin moment. Nanowires of Fe/MgO/Fe showed higher saturation magnetization by a factor of 2.7 compared to planar thin films of Fe/MgO/Fe at 1.5 kOe. The enhanced magnetic properties likely resulted from shape anisotropy of the nanowires and as well as the hybridization that occur between the π- electronic states of carbon and 3d-bands of the Fe-surface.

Enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers by inhibiting Ta diffusion

International Nuclear Information System (INIS)

Li, Xu-Jing; Jiang, Shao-Long; Zhang, Jing-Yan; Liu, Qian-Qian; Liu, Yi-Wei; Zhao, Jian-Cheng; Wu, Zheng-Long; Feng, Chun; Li, Ming-Hua; Yu, Guang-Hua

2016-01-01

Graphical abstract: To reveal the underlying mechanism of Mg influence on the enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers, the X-ray photoelectron spectroscopy analysis have been performed. It is found that a certain amount of Mg interlayer at the CoFeB/MgO interface could prevent the Ta oxidation to some extent due to the oxygen deficit MgO_x (x < 1), and consequently lower the diffusion motivation of Ta from the bottom layer to the CoFeB/MgO interfaces to some extent during the annealing process. The prevention of Ta diffusion realizes the effective hybridization of Fe and O at the CoFeB/MgO interface and maintains interfacial magnetic anisotropy (K_C_o_F_e_B_/_M_g_O). As a result, the perpendicular magnetic anisotropy at high annealing temperatures was maintained. - Highlights: • High annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers was realized. • X-ray photoelectron spectroscopy analysis has been performed to explore the reasons. • The prevention of Ta diffusion was realized by introducing Mg at the CoFeB/MgO interface. - Abstracts: To reveal the underlying mechanism of Mg influence on the enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers, the X-ray photoelectron spectroscopy analysis has been performed. It is found that a certain amount of Mg interlayer at the CoFeB/MgO interface could prevent the Ta oxidation, and consequently lower the diffusion motivation of Ta from the bottom layer to the CoFeB/MgO interfaces to some extent in the annealing process. The prevention of Ta diffusion realizes the effective hybridization of Fe and O at the CoFeB/MgO interface and maintains interfacial magnetic anisotropy (KCoFeB/MgO). As a result, the perpendicular magnetic anisotropy at high annealing temperatures is maintained

Perpendicular magnetic anisotropy in Ta|Co40Fe40B20|MgAl2O4 structures and perpendicular CoFeB|MgAl2O4|CoFeB magnetic tunnel junction

KAUST Repository

Tao, B. S.

2014-09-08

Magnetic properties of Co40Fe40B20(CoFeB) thin films sandwiched between Ta and MgAl2O4layers have been systematically studied. For as-grown state, Ta/CoFeB/MgAl2O4structures exhibit good perpendicular magnetic anisotropy (PMA) with interface anisotropy Ki=1.22erg/cm2, which further increases to 1.30erg/cm2after annealing, while MgAl2O4/CoFeB/Ta multilayer shows in-plane magnetic anisotropy and must be annealed in order to achieve PMA. For bottom CoFeB layer, the thickness window for PMA is from 0.6 to 1.0nm, while that for top CoFeB layer is between 0.8 and 1.4nm. Perpendicular magnetic tunnel junctions (p-MTJs) with a core structure of CoFeB/MgAl2O4/CoFeB have also been fabricated and tunneling magnetoresistance ratio of about 36% at room temperature and 63% at low temperature have been obtained. The intrinsic excitations in the p-MTJs have been identified by inelastic electron-tunneling spectroscopy.

Perpendicular magnetic anisotropy in Ta|Co40Fe40B20|MgAl2O4 structures and perpendicular CoFeB|MgAl2O4|CoFeB magnetic tunnel junction

KAUST Repository

Tao, B. S.; Li, D. L.; Yuan, Z. H.; Liu, H. F.; Ali, S. S.; Feng, J. F.; Wei, H. X.; Han, X. F.; Liu, Y.; Zhao, Y. G.; Zhang, Q.; Guo, Zaibing; Zhang, Xixiang

2014-01-01

Magnetic properties of Co40Fe40B20(CoFeB) thin films sandwiched between Ta and MgAl2O4layers have been systematically studied. For as-grown state, Ta/CoFeB/MgAl2O4structures exhibit good perpendicular magnetic anisotropy (PMA) with interface anisotropy Ki=1.22erg/cm2, which further increases to 1.30erg/cm2after annealing, while MgAl2O4/CoFeB/Ta multilayer shows in-plane magnetic anisotropy and must be annealed in order to achieve PMA. For bottom CoFeB layer, the thickness window for PMA is from 0.6 to 1.0nm, while that for top CoFeB layer is between 0.8 and 1.4nm. Perpendicular magnetic tunnel junctions (p-MTJs) with a core structure of CoFeB/MgAl2O4/CoFeB have also been fabricated and tunneling magnetoresistance ratio of about 36% at room temperature and 63% at low temperature have been obtained. The intrinsic excitations in the p-MTJs have been identified by inelastic electron-tunneling spectroscopy.

Structural and magnetic properties of Mg-Zn ferrites (Mg{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4}) prepared by sol-gel method

Energy Technology Data Exchange (ETDEWEB)

Reyes-Rodríguez, Pamela Yajaira, E-mail: pamela2244_4@hotmail.com [Cinvestav-Unidad Saltillo, Av. Industrial Metalúrgica #1062, Parque Industrial Saltillo-Ramos Arizpe, CP 25900, México (Mexico); Cortés-Hernández, Dora Alicia; Escobedo-Bocardo, José Concepción; Almanza-Robles, José Manuel; Sánchez-Fuentes, Héctor Javier; Jasso-Terán, Argentina; De León-Prado, Laura Elena [Cinvestav-Unidad Saltillo, Av. Industrial Metalúrgica #1062, Parque Industrial Saltillo-Ramos Arizpe, CP 25900, México (Mexico); Méndez-Nonell, Juan [Centro de Investigación en Materiales Avanzados, Ave. Miguel Cervantes #120, Complejo Industrial Chihuahua, CP 31109 Chihuahua, México (Mexico); Hurtado-López, Gilberto Francisco [Centro de Investigación en Química Aplicada, Blvd. Enrique Reyna Hermosillo #140, CP 25294 Saltillo, Coahuila, México (Mexico)

2017-04-01

In this study, the Mg{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} nanoparticles (x=0–0.9) were prepared by sol-gel method. These ferrites exhibit an inverse spinel structure and the lattice parameter increases as the substitution of Zn{sup 2+} ions is increased. At lower Zn content (0.1≤x≤0.5), saturation magnetization (Ms) increases, while it decreases at higher Zn content (x≥6). The remnant magnetization (0.17–2.0 emu/g) and coercive field (6.0–60 Oe) indicate a ferrimagnetic behavior. The average core diameter of selected ferrites is around 15 nm and the nanoparticles morphology is quasi spherical. The heating ability of some Mg{sub 0.9}Zn{sub 0.1}Fe{sub 2}O{sub 4} and Mg{sub 0.7}Zn{sub 0.3}Fe{sub 2}O{sub 4} aqueous suspensions indicates that the magnetic nanoparticles can increase the medium temperature up to 42 °C in a time less than 10 min - Highlights: • Magnetic nanoparticles of Mg{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} were synthesized by sol-gel method. • Nanoparticles showing a single spinel crystalline structure were obtained. • Aqueous suspensions of Mg{sub 0.7}Zn{sub 0.3}Fe{sub 2}O{sub 4} and Mg{sub 0.9}Zn{sub 0.1}Fe{sub 2}O{sub 4} show heating ability.

Pharmacokinetics of sugammadex 16 mg/kg in healthy Chinese volunteers.

Science.gov (United States)

de Kam, Pieter-Jan; Hou, Jie; Wang, Zaiqi; Lin, Wen Hong; van den Heuvel, Michiel

2015-06-01

Elimination of sugammadex occurs predominantly via the kidneys, with the majority of the drug excreted unchanged in the urine. To date, most studies with sugammadex have been performed in non-Asian populations. The objectives of this open-label study were to determine the pharmacokinetics (PK) and safety of single-dose sugammadex (16 mg/kg) in healthy Chinese adult volunteers. 12 Chinese subjects (6 male; 6 female) received intravenous sugammadex (16 mg/kg) as a 10-second bolus infusion. Blood samples were collected pre-sugammadex and at regular intervals up to 24 hours post-sugammadex for PK assessment. Safety was assessed via AEs, vital signs, electrocardiogram, and laboratory parameters. Following sugammadex 16 mg/kg infusion, peak sugammadex concentration was 197 μg/mL, clearance was 99.7 mL/min, and apparent volume of distribution at equilibrium was 10.5 L. Plasma sugammadex concentrations showed a polyexponential decline over time, with an overall geometric mean (CV%) terminal half-life of 145 minutes (17.9%) (139 minutes (17.7%) for males; 152 minutes (18.6%) for females). No influence of gender on the PK of sugammadex was observed. Three subjects experienced an adverse events (AE) (dysgeusia of mild intensity), which was considered possibly or probably related to sugammadex. There were no clinically significant changes in vital signs, electrocardiography or laboratory parameters. PK of sugammadex (16 mg/kg) was characterized in healthy Chinese subjects. Overall between-subject variability on clearance and apparent volume of distribution was ~ 10%. Sugammadex was generally well tolerated.

Morphology, magnetic and resonance properties of Fe/MgO multilayers

International Nuclear Information System (INIS)

Garcia-Garcia, A; Algarabel, P A; Ibarra, M R; Vovk, A; Strichovanec, P; Pardo, J A; Magen, C; Golub, V; Salyuk, O

2011-01-01

Magnetic, resonance and transport properties of Fe(t nm)/MgO(3.0 nm) multilayers prepared by pulsed laser deposition were investigated. Comparison of the data allows conclusions on Fe layers morphology. For t 1.25 nm a continuous coverage of MgO by Fe takes place. However, the morphology of Fe layers is rough. This causes the appearance of magnetostatic resonance modes analogous to those observed for continuous films deposited on embossed surfaces.

Magnesium Aminoclay-Fe3O4 (MgAC-Fe3O4 Hybrid Composites for Harvesting of Mixed Microalgae

Directory of Open Access Journals (Sweden)

Bohwa Kim

2018-05-01

Full Text Available In this paper, we describe the synthesis of magnesium aminoclay-iron oxide (MgAC-Fe3O4 hybrid composites for microalgae-harvesting application. MgAC-templated Fe3O4 nanoparticles (NPs were synthesized in different ratios of MgAC and Fe3O4 NPs. The uniform distribution of Fe3O4 NPs in the MgAC matrix was confirmed by transmission electron microscopy (TEM. According to obtained X-ray diffraction (XRD patterns, increased MgAC loading leads to decreased intensity of the composites’ (311 plane of Fe3O4 NPs. For harvesting of Chlorella sp. KR-1, Scenedesmus obliquus and mixed microalgae (Chlorella sp. KR-1/ Scenedesmus obliquus, the optimal pH was 4.0. At higher pHs, the microalgae-harvesting efficiencies fell. Sample #1, which had the highest MgAC concentration, showed the most stability: the harvesting efficiencies for Chlorella sp. KR-1, Scenedesmus obliquus, and mixed microalgae were reduced only to ~50% at pH = 10.0. The electrostatic interaction between MgAC and the Fe3O4 NPs in the hybrid samples by microalgae, as confirmed by zeta potential measurements, were attributed to the harvesting mechanisms. Moreover, the zeta potentials of the MgAC-Fe3O4 hybrid composites were reduced as pH was increased, thus diminishing the microalgae-harvesting efficiencies.

Strength of FePd/MgO and FePt/MgO interfaces from first principles

Science.gov (United States)

Černý, M.

2018-04-01

Cleavage characteristics such as the cleavage energy and the cleavage stress of FePd/MgO and FePt/MgO interfaces are computed from first principles. Considering several possible cleavage planes, the weakest link in these systems is found as the plane with the lowest cleavage stress. This weakest plane is identified in both systems with the interface plane, where the cohesion is reduced by 30% compared to the MgO bulk. Two distinct models of tensile test are employed to verify the results and convergence of computed values with respect to size of the simulation cell is discussed.

Efficacy, safety and pharmacokinetics of sugammadex 4 mg kg-1 for reversal of deep neuromuscular blockade in patients with severe renal impairment.

Science.gov (United States)

Panhuizen, I F; Gold, S J A; Buerkle, C; Snoeck, M M J; Harper, N J N; Kaspers, M J G H; van den Heuvel, M W; Hollmann, M W

2015-05-01

This study evaluated efficacy and safety of sugammadex 4 mg kg(-1) for deep neuromuscular blockade (NMB) reversal in patients with severe renal impairment (creatinine clearance [CLCR] Sugammadex 4 mg kg(-1) was administered at 1-2 post-tetanic counts for reversal of rocuronium NMB. Primary efficacy variable was time from sugammadex to recovery to train-of-four (T4/T1) ratio 0.9. Equivalence between groups was demonstrated if two-sided 95% CI for difference in recovery times was within -1 to +1 min interval. Pharmacokinetics of rocuronium and overall safety were assessed. The intent-to-treat group comprised 67 patients (renal n=35; control n=32). Median (95% CI) time from sugammadex to recovery to T4/T1 ratio 0.9 was 3.1 (2.4-4.6) and 1.9 (1.6-2.8) min for renal patients vs controls. Estimated median (95% CI) difference between groups was 1.3 (0.6-2.4) min; thus equivalence bounds were not met. One control patient experienced acceleromyography-determined NMB recurrence, possibly as a result of premature sugammadex (4 mg kg(-1)) administration, with no clinical evidence of NMB recurrence observed. Rocuronium, encapsulated by Sugammadex, was detectable in plasma at day 7 in 6 patients. Bioanalytical data for sugammadex were collected but could not be used for pharmacokinetics. Sugammadex 4 mg kg(-1) provided rapid reversal of deep rocuronium-induced NMB in renal and control patients. However, considering the prolonged sugammadex-rocuronium complex exposure in patients with severe renal impairment, current safety experience is insufficient to support recommended use of sugammadex in this population. NCT00702715. © The Author 2015. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Elemental moment variation of bcc Fe{sub x}Mn{sub 1−x} on MgO(001)

Energy Technology Data Exchange (ETDEWEB)

Bhatkar, H.; Snow, R.J. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Arenholz, E. [Advanced Light Source, Lawrence Berkeley National Laboratories, Berkeley, CA 94720 (United States); Idzerda, Y.U., E-mail: idzerda@montana.edu [Department of Physics, Montana State University, Bozeman, MT 59717 (United States)

2017-02-01

We report the growth, structural characterization, and electronic structure evolution of epitaxially grown bcc Fe{sub x}Mn{sub 1−x} on MgO(001). It is observed that the 20 nm thick Fe{sub x}Mn{sub 1−x} alloy films remained bcc from 0.65≤x≤1, much beyond the bulk stability range of 0.88≤x≤1. X-ray absorption spectroscopy and X-ray magnetic circular dichroism show that both the Fe and Mn L{sub 3} binding energies slightly increase with Mn incorporation and that the elemental moment of Fe in the 20 nm crystalline bcc alloy film remain nearly constant, then shows a dramatic collapse near x~0.84. The Mn MCD intensity is found to be small at all compositions that exhibit ferromagnetism - Highlights: • Bcc Fe{sub x}Mn{sub 1−x} films were stabilized beyond bulk range by epitaxial growth on MgO. • XMCD shows negligible moment in Mn regardless of composition. • Fe moment stays constant until 84% Mn concentration. • Magnetic moment suddenly collapses before any structural change seen in RHEED.

Decorating Mg/Fe oxide nanotubes with nitrogen-doped carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Cao Yong, E-mail: caoyangel@126.com [Institute of Environment and Municipal Engineering, North China Institute of Water Conservancy and Hydroelectric Power, Zhengzhou 450011 (China); Jiao Qingze, E-mail: jiaoqz@bit.edu.cn [School of Chemical Engineering and the Environment, Beijing Institute of Technology, Beijing 100081 (China); Zhao Yun [School of Chemical Engineering and the Environment, Beijing Institute of Technology, Beijing 100081 (China); Dong Yingchao [Materials and Surface Science Institute (MSSI), University of Limerick, Limerick (Ireland)

2011-09-22

Graphical abstract: Highlights: > Mg/Fe oxide nanotubes arrayed parallel to each other were prepared by an AAO template method. > The Mg/Fe oxide nanotubes decorated with CN{sub x} were realized by CVD of ethylenediamine on the outer surface of oxide nanotubes. > The magnetic properties of Mg/Fe oxide nanotubes were highly improved after being decorated. - Abstract: Mg/Fe oxide nanotubes decorated with nitrogen-doped carbon nanotubes (CN{sub x}) were fabricated by catalytic chemical vapor deposition of ethylenediamine on the outer surface of oxide nanotubes. Mg/Fe oxide nanotubes were prepared using a 3:1 molar precursor solution of Mg(NO{sub 3}){sub 2} and Fe(NO{sub 3}){sub 3} and anodic aluminum oxide as the substrate. The obtained samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM). The XRD pattern shows that the oxide nanotubes are made up of MgO and Fe{sub 2}O{sub 3}. TEM and SEM observations indicate the oxide nanotubes are arrayed roughly parallel to each other, and the outer surface of oxide nanotubes are decorated with CN{sub x}. XPS results show the nitrogen-doped level in CN{sub x} is about 7.3 at.%. Magnetic measurements with VSM demonstrate the saturated magnetization, remanence and coercivity of oxide nanotubes are obvious improved after being decorated with CN{sub x}.

Investigations on FCAM-III (Ca2.38Mg2.09Fe3+10.61Fe2+1.59Al9.33O36): A new homologue of the aenigmatite structure-type in the system CaO-MgO-Fe2O3-Al2O3

Science.gov (United States)

Zöll, Klaus; Kahlenberg, Volker; Krüger, Hannes; Tropper, Peter

2018-02-01

In the course of a systematic study of a part of the quaternary system Fe2O3-CaO-Al2O3-MgO (FCAM) the previously unknown compound Ca2.38Mg2.09Fe3+10.61Fe2+1.59Al9.33O36 (FCAM-III) has been synthesized. By analogy with the so-called SFCA series [1-5], our investigation in the system of FCAM shows the existence of a stoichiometric homologous series M14+6nO20+8n, where M = Fe, Ca, Al, Mg and n = 1 or 2. In air, we can prove the formation of coexisting FCAM-III and FCAM-I solid solutions at 1400 °C. By increasing the temperature up to 1425 °C FCAM-I disappears completely and FCAM-III co-exists with magnesiumferrite and a variety of calcium iron oxides. At 1450 °C FCAM-III breaks down to a mixture of FCAM-I again as well as magnesioferrite and melt. Small single-crystals of FCAM-III up to 35 μm in size could be retrieved from the 1425 °C experiment and were subsequently characterized using electron microprobe analysis and synchroton X-ray single-crystal diffraction. Finally the Fe2+/Fetot ratio was calculated from the total iron content based on the crystal-chemical formula obtained from EMPA measurements and charge balance considerations. FCAM-III or Ca2.38Mg2.09Fe3+10.61Fe2+1.59Al9.33O36 has a triclinic crystal structure (space group P 1 ̅). The basic crystallographic data are: a = 10.223(22) Å, b = 10.316(21) Å, c = 14.203(15) Å, α = 93.473(50)°, β = 107.418(67)°, γ = 109.646(60)°, V = 1323.85(2) ų, Z = 1. Using Schreinemaker's technique to analyze the phase relations in the system Fe2O3-CaO-Al2O3-MgO it was possible to obtain the semi-quantitative stability relations between the participating phases and construct a topologically correct phase sequence as a function of T and fO2. The analysis shows that Ca2Al0.5Fe1.5O5 (C2A0.25F0.75) and CaAl1.5Fe2.5O7 (CA0.75F1.25) with higher calculated Fe2+ contents are preferably formed at lower oxygen fugacity and react to CaAl0.5Fe1.5O4 (CA0.25F0.75) by increasing fO2. Spinel-type magnesium

Effect of Fe on the formation and H-sorption properties of Mg2FeH6

Energy Technology Data Exchange (ETDEWEB)

Asselli, A. A.C. [Universidade Federal de Sao Carlos (UFSCar), Sao Carlos, SP (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais; Ishikawa, T.T.; Neves, W.R.; Kiminami, C.S.; Botta, W.J. [Universidade Federal de Sao Carlos (UFSCar), Sao Carlos, SP (Brazil). Departamento de Engenharia de Materiais

2009-07-01

Full text: The compound Mg- - - -2- -FeH6- - - - was synthesized from a 2Mg+Fe mixture in a single process by reactive milling (RM) under hydrogen atmosphere at room temperature. The complex hydride was prepared from Mg powder and granulated (1-2 mm) or powdered Fe using a planetary mill. The phase evolution during different milling times (from 3 to 72h) was investigated by X-ray diffraction (XRD) technique. The dehydrogenation behavior of the so-formed metal hydride was investigated by differential scanning calorimetry (DSC). The use of powdered iron as starting material promoted conversion to complex hydride at shorter milling times than when granulated iron was used. On the other hand, the DSC analysis show a decrease in temperature of release of hydrogen for the as-milled 2Mg+Fe (Fe granulated) mixtures. Scanning (SEM) and transmission electron microscopy (TEM) have been carried out to correlate the structural characteristics of the as-milled materials to the decomposition behaviors. (author)

Gigantic perpendicular magnetic anisotropy of heavy transition metal cappings on Fe/MgO(0 0 1)

Science.gov (United States)

Taivansaikhan, P.; Odkhuu, D.; Rhim, S. H.; Hong, S. C.

2017-11-01

Effects of capping layer by 5d transition metals (TM = Hf, Ta, W, Re, Os, Ir, Pt, and Au) on Fe/MgO(0 0 1), a typical magnetic tunneling junction, are systematically investigated using first-principles calculation for magnetism and magnetocrystalline-anisotropy (MCA). The early TMs having less than half-filled d bands favor magnetization antiparallel to Fe, whereas the late TMs having more than half-filled d bands favor parallel, which is explained in the framework of kinetic exchange energy. The Os capping, isovalent to Fe, enhances MCA significantly to gigantic energy of +11.31 meV/cell, where positive contribution is mostly from the partially filled majority d bands of magnetic quantum number of |m| = 1 along with stronger spin-orbit coupling of Os than Fe. Different TM cappings give different MCA energies as the Fermi level shifts according to the valence of TM: Re and Ir, just one valence more or less than Os, have still large PMCA but smaller than the Os. In the W and Pt cappings, valence difference by two, PMCA are further reduced; MCAs are lowered compared to Fe/MgO(0 0 1) by the cappings of the very early TMs (Hf and Ta), while the very late TM (Au) switches sign to in-plane MCA.

Microstructure and magnetic properties of nanocomposite FePt/MgO and FePt/Ag films

International Nuclear Information System (INIS)

Chen, S.C.; Kuo, P.C.; Sun, A.C.; Chou, C.Y.; Fang, Y.H.; Wu, T.H.

2006-01-01

An in-plane magnetic anisotropy of FePt film is obtained in the MgO 5 nm/FePt t nm/MgO 5 nm films (where t=5, 10 and 20 nm). Both the in-plane coercivity (H c- parallel ) and the perpendicular magnetic anisotropy of FePt films are increased when introducing an Ag-capped layer instead of MgO-capped layer. An in-plane coercivity is 3154 Oe for the MgO 5 nm/FePt 10 nm/MgO 5 nm film, and it can be increased to 4846 Oe as a 5 nm Ag-capped layer instead of MgO-capped layer. The transmission electron microscopy (TEM)-energy disperse spectrum (EDS) analysis shows that the Ag mainly distributed at the grain boundary of FePt, that leads the increase of the grain boundary energy, which will enhance coercivity and perpendicular magnetic anisotropy of FePt film

Synthesis of Mg2FeH6 containing as additives transition metal and transition metal fluorides or carbon

International Nuclear Information System (INIS)

Zepon, G.; Leiva, D.R.; Botta, W.J.

2010-01-01

The Mg 2 FeH 6 is a promising way of storing hydrogen in solid form, composed by elements that have low cost and, at the same time, high volumetric storage density: 150 kg H 2 /m 3 . However, this complex hydride is not easily synthesized as a single phase material. The hydrogen sorption high temperature and slow kinetics are the major limitations for the practical application of the Mg 2 FeH 6 as a hydrogen storage material. Little is known about the effects of additives in Mg 2 FeH 6 based nanocomposites in this work were synthesized by MAE under hydrogen atmosphere nanocomposites based on Mg 2 FeH 6 containing additives as transition metals, transition metals fluorides of transition metals or carbon, in order to obtain information on the effects of the selected additives. To this end, we used characterization techniques such as XRD, SEM and TEM, thermal analysis by DSC and curves made in apparatus PCT.(author)

Perbandingan Granisetron 0,01 mg/KgBb dengan Ondansetron 0,08 Mg/Kg.Bb Untuk Mencegah Mual Muntah Pascaoperasi Dini Mastektomi Radikal Modifikasi

Directory of Open Access Journals (Sweden)

Budi Fitriyana

2013-04-01

Full Text Available Postoperative nausea and vomiting not only cause discomfort to the patient, but also lead to electrolyte imbalance, regurgitation and aspiration, bleeding and loss of surgical sutures. Patients who experience postoperative nausea and vomiting will require further attention and treatment which of course increases the cost of medical services. Women who underwent mastectomy with accompanying decision underarm lymph nodes have a high risk of postoperative nausea and vomiting. Many anti-vomiting are given including antihistamines, butyrophenon, and dopamine receptor antagonists have been reported to have undesirable side effects including excessive sedation, hypotension, dry mouth, dysphoria, hallucinations and extrapyramidal effects. 5 HT3 receptor antagonists provide a major advancement for treatment of postoperative nausea and vomiting due to fewer side effects when compared with anti-vomiting medications before. This study will compare the two drugs 5 HT3 receptor antagonist granisetron with ondansetron in preventing postoperative nausea and vomiting modified radical mastectomy early. Conducted research on 58 patients ASA I and II modified radical mastectomy is performed under general anesthesia. Sampling was carried out using double-blind randomized controlled trial. Samples were divided into two groups by block randomization. Group G is given granisetron 0.01 gr / kg.bb and group O is given ondansetron 0.08 mg / kg.bb. Drug treatment is administered intravenously 30 minutes before the surgery ended on a complete evaluation of blood pressure, heart rate, oxygen saturation and length of surgery. Postoperative nausea and vomiting shortly after surgery assessed every hour until 6 hours after surgery (early postoperative nausea and vomiting to 4 scale (0-3. Data were analyzed by t-test, Chi-square test, Mann-Whitney test and Fisher's Exact test on Windows SPSS ver.16 The results suggest there is a tendency complaints of postoperative nausea and

Preparation of Mg2FeH6 Nanoparticles for Hydrogen Storage Properties

Directory of Open Access Journals (Sweden)

N. A. Niaz

2013-01-01

Full Text Available Magnesium (Mg and iron (Fe nanoparticles are prepared by thermal decomposition of bipyridyl complexes of metals. These prepared Mg-Fe (2 : 1 nanoparticles are hydrogenated under 4 MPa hydrogen pressure and 673 K for 48 hours to achieve Mg2FeH6. Their structural analysis was assessed by applying manifold techniques. The hydrogen storage properties of prepared compound were measured by Sieverts type apparatus. The desorption kinetics were measured by high pressure thermal desorption spectrometer (HP-TDS. More than 5 wt% hydrogen released was obtained by the Mg2FeH6 within 5 min, and during rehydrogenation very effective hydrogen absorption rate was observed by the compound.

Pulsed laser deposition of SmFeAsO1-δ on MgO(100) substrates

Science.gov (United States)

Haindl, Silvia; Kinjo, Hiroyuki; Hanzawa, Kota; Hiramatsu, Hidenori; Hosono, Hideo

2018-04-01

Layered iron oxyarsenides are novel interesting semimetallic compounds that are itinerant antiferromagnets in their ground state with a transition to high-temperature superconductivity upon charge carrier doping. The rare earth containing mother compounds offer rich physics due to different antiferromagnetic orderings: the alignment of Fe magnetic moments within the FeAs sublattice, which is believed to play a role for the superconducting pairing mechanism, and the ordering of the rare-earth magnetic moments at low temperatures. Here, we present thin film preparation and a film growth study of SmFeAsO on MgO(100) substrates using pulsed laser deposition (PLD). In general, the PLD method is capable to produce iron oxyarsenide thin films, however, competition with impurity phase formation narrows the parameter window. We assume that the film growth in an ultra-high vacuum (UHV) environment results in an oxygen-deficient phase, SmFeAsO1-δ. Despite the large lattice misfit, we find epitaxial oxyarsenide thin film growth on MgO(100) with evolving film thickness. Bragg reflections are absent in very thin films although they locally show indications for pseudomorphic growth of the first unit cells. We propose the possibility for a Stranski-Krastanov growth mode as a result of the large in-plane lattice misfit between the iron oxypnictide and the MgO unit cells. A columnar 3-dimensional film growth mode dominates and the surface roughness is determined by growth mounds, a non-negligible parameter for device fabrication as well as in the application of surface sensitive probes. Furthermore, we found evidence for a stratified growth in steps of half a unit cell, i.e. alternating growth of (FeAs)- and (SmO1-δ)+ layers, the basic structural components of the unit cell. We propose a simple model for the growth kinetics of this compound.

Ethylbenzene dehydrogenation over FeOx/(Mg,Zn)(Al)O catalysts derived from hydrotalcites: Role of MgO as basic sites

KAUST Repository

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

2011-01-01

A series of Mg3-xZnxFe0.5Al0.5 mixed oxide catalysts derived from hydrotalcites were tested in the ethylbenzene dehydrogenation to styrene in He atmosphere at 550 °C. The catalysts were prepared by coprecipitation from the nitrates of metal components followed by calcination to mixed oxides at 550 °C. A part of Mg2+ in Mg 3Fe0.5Al0.5 mixed oxide was replaced with Zn2+ to test the effect of MgO as the support. The mixed oxides were composed of periclase and spinel-type compounds with a high surface area of 100-180m2gcat-1. Mössbauer and XPS measurements indicated the presence of Fe3+ on the catalysts and H2-TPR measurement suggested that the dehydrogenation reaction is catalyzed by the reduction-oxidation between Fe3+/Fe2+. The activity of Mg3-xZnxFe0.5Al0.5 mixed oxide decreased with increasing x, indicating an important role of MgO on the activity. Both CO2-TPD measurements as well as IR measurements of adsorbed CO2 clearly indicated the presence of basic sites of Mg 2+O2- on the catalysts. It seems that the combination of Mg2+O2- and Fe3+ was essential for the catalytic activity. It is concluded that the surface base sites generated on O2- bound Mg2+ near Fe3+ sites are responsible for H+-abstraction; the dehydrogenation of ethylbenzene was initiated by the H+ abstraction on Mg2+O2- basic sites, and accelerated by the reduction-oxidation of Fe3+/Fe2+ active species. © 2011 Elsevier B.V.

Ethylbenzene dehydrogenation over FeOx/(Mg,Zn)(Al)O catalysts derived from hydrotalcites: Role of MgO as basic sites

KAUST Repository

Balasamy, Rabindran J.

2011-05-01

A series of Mg3-xZnxFe0.5Al0.5 mixed oxide catalysts derived from hydrotalcites were tested in the ethylbenzene dehydrogenation to styrene in He atmosphere at 550 °C. The catalysts were prepared by coprecipitation from the nitrates of metal components followed by calcination to mixed oxides at 550 °C. A part of Mg2+ in Mg 3Fe0.5Al0.5 mixed oxide was replaced with Zn2+ to test the effect of MgO as the support. The mixed oxides were composed of periclase and spinel-type compounds with a high surface area of 100-180m2gcat-1. Mössbauer and XPS measurements indicated the presence of Fe3+ on the catalysts and H2-TPR measurement suggested that the dehydrogenation reaction is catalyzed by the reduction-oxidation between Fe3+/Fe2+. The activity of Mg3-xZnxFe0.5Al0.5 mixed oxide decreased with increasing x, indicating an important role of MgO on the activity. Both CO2-TPD measurements as well as IR measurements of adsorbed CO2 clearly indicated the presence of basic sites of Mg 2+O2- on the catalysts. It seems that the combination of Mg2+O2- and Fe3+ was essential for the catalytic activity. It is concluded that the surface base sites generated on O2- bound Mg2+ near Fe3+ sites are responsible for H+-abstraction; the dehydrogenation of ethylbenzene was initiated by the H+ abstraction on Mg2+O2- basic sites, and accelerated by the reduction-oxidation of Fe3+/Fe2+ active species. © 2011 Elsevier B.V.

Synthesis and magnetic properties of ferrites spinels Mg{sub x}Cu{sub 1-x}Fe{sub 2}O{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Mounkachi, O.; Hamedoun, M. [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); Belaiche, M. [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); Hassan II Academy of Science and Technology, Rabat (Morocco); Laboratoire de Magnetisme, Materiaux Magnetiques, Microonde et Ceramique, Ecole Normale Superieure, Universite Mohammed V-Agdal, B.P. 9235, Ocean, Rabat (Morocco); Benyoussef, A. [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); Hassan II Academy of Science and Technology, Rabat (Morocco); LMPHE, (URAC 12), Faculte des Sciences, Universite Mohammed V-Agdal, Rabat (Morocco); Masrour, R. [Laboratory of Materials, Process, Environment and Quality, Cady Ayad University, National School of Applied Sciences, Safi (Morocco); El Moussaoui, H. [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); LMPHE, (URAC 12), Faculte des Sciences, Universite Mohammed V-Agdal, Rabat (Morocco); Sajieddine, M., E-mail: hamedoun@hotmail.com [Faculte des Sciences et Techniques, Universite Moulay Slimane, Beni Mellal (Morocco)

2012-01-01

Polycrystalline Mg{sub 0.6}Cu{sub 0.4}Fe{sub 2}O{sub 4} ferrites have been prepared using solid-state reaction technique. Their structural and magnetic properties have been studied, using X-ray diffraction and magnetic measurements. Using mean field theory and high-temperature series expansions (HTSE), extrapolated with the pade approximants method, the magnetic properties of Mg{sub 1-x}Cu{sub x}Fe{sub 2}O{sub 4} have been studied. The nearest neighbor super-exchange interactions for intra-site and inter-site of the Mg{sub 1-x}Cu{sub x}Fe{sub 2}O{sub 4} ferrites spinels, in the range 0{<=}x{<=}1, have been computed using the probability approach, based on Moessbauer data. The Curie temperature T{sub c} is calculated as a function of Mg concentration. The obtained theoretical results are in good agreement with experimental ones obtained by magnetic measurements.

Behavior of methyl orange and orange 10 (orange G) in the presence of hydrotalcite type compounds of Mg/Al and Mg/Fe; Comportamiento de naranja de metilo y naranja 10 (orange G) en presencia de compuestos tipo hidrotalcita de mg/Al y Mg/Fe

Energy Technology Data Exchange (ETDEWEB)

Cruz N, G.

2015-07-01

This work is focused on studying the sorption capacity of methyl orange dye (Nm) and orange 10 (N-10) in the presence of hydrotalcite type compounds of Mg/Al and Mg/Fe uncalcined and calcined previously at 500 degrees Celsius. Sorption isotherms were determined and the study of the kinetics of sorption was performed. The materials were characterized before and after sorption processes of these dyes by X-ray diffraction, scanning electron microscopy, the specific surface area determination by the Brunauer-Emmett-Teller method, thermogravimetry coupled to mass and infrared spectrometry. The hydrotalcite type compounds reported in this paper were prepared in the laboratory and their acronyms are: HTMgAlG1, HTMgAlMO, HTMgFeG1 and HTMgFeG2. Note that in this work the best conditions for preparing compounds of Mg/Fe were found. From patterns of X-ray diffraction was identified the typical crystal structure of the hydrotalcite type compounds. By scanning electron microscopy the morphology could be determined in the form of flakes characteristics of these compounds. Likewise with elemental analysis of energy dispersive X-ray spectroscopy the presence of Mg, Al, Fe and C, elements of interest for this study was determined. The compounds presented a specific surface area relatively high from 80 to 120 m{sup 2}/g. Thermogravimetry results presented spectra of mass loss very characteristic associated to water losses, dehydroxylation and decarboxylation. The characteristic bands of water and carbonate were assigned by infrared spectroscopy and the bands corresponding to the dyes sulfonates were identified only for the calcined materials. The sorption capacities found of these compounds were as follows: for Nm in the compound HTMgAlG1 uncalcined was 17.82 mg/g for an initial concentration of 200 mg/L and for calcined (HTMgAlMOcal) of 99.8 mg/g with and initial concentration of 1000 mg/L. Moreover, the sorption capacity of the dye N-10 in this same material was 17.92 mg/g and 99

Hydrogen kinetics studies of MgH2-FeTi composites

Science.gov (United States)

Meena, Priyanka; Jangir, Mukesh; Singh, Ramvir; Sharma, V. K.; Jain, I. P.

2018-05-01

MgH2 + x wt% FeTi (x=10, 25, 50) nano composites were ball milled to get nano structured material and characterized for structural, morphological and thermal properties. XRD of the milled samples revealed the formation of MgH2, FeTi, Fe2Ti and H0.06FeTi phases. Morphological studies by SEM were undertaken to investigate the effect of hydrogenation of nanostructure alloy. EDX confirmed elemental composition of the as-prepared alloy. TGA studies showed higher desorption temperature for milled MgH2 compared to x wt% FeTi added MgH2. Activation energy for hydrogen desorption was found to be -177.90, -215.69, -162.46 and -87.93 kJ/mol for milled MgH2 and Mg2+x wt% FeTi (10, 25, 50), showing 89.97 kJ/ mol reduction in activation energy for 50 wt% alloy additives resulting in improved hydrogen storage capacity. DSC investigations were carried out to investigate the effect of alloy on hydrogen absorption behavior of MgH2.

Electromagnetic and microwave absorption properties of BaMg{sub x}Co{sub 1−x}TiFe{sub 10}O{sub 19}

Energy Technology Data Exchange (ETDEWEB)

Chen, Jing [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Meng, Pingyuan [Huzhou Innovation Center of Advanced Materials, Shanghai Institute of Ceramics Chinese Academy of Sciences, Huzhou 215100 (China); Wang, Meiling [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Zhou, Guanchen [School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Wang, Xinqing [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Xu, Guangliang, E-mail: xuguangliang@swust.edu.cn [School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China)

2016-09-15

To improve the impedance matching and then achieve a better microwave absorption performance in electromagnetic absorber, the Mg{sup 2+} was added to occupy the sites of Co{sup 2+} in hexagonal-type ferrite BaCoTiFe{sub 10}O{sub 19}. BaMg{sub x}Co{sub 1−x}TiFe{sub 10}O{sub 19} were synthesized by a simple sol-gel combustion technique and the phase of BaMg{sub x}Co{sub 1−x}TiFe{sub 10}O{sub 19} was confirmed by X-ray diffraction analysis (XRD). The grain size of BaMg{sub x}Co{sub 1−x}TiFe{sub 10}O{sub 19} was in the range of 100–400 nm and crystal particles were refined with the augment of doped Mg{sup 2+}. Based on the static magnetic measurement, the coercivity (H{sub c}) increased and the saturation magnetization (M{sub s}) decreased as the x increased. Moreover, it was found that BaMg{sub 0.4}Co{sub 0.6}TiFe{sub 10}O{sub 19} possessed a maximum reflection loss of −33.7 dB with a matching thickness of 2.0 mm measured by the vector net-analyzer in the frequency of 0.5–18 GHz, which also had a bandwidth below −20 dB ranging from 11.5 GHz to 17.2 GHz. Meanwhile, the permeability of the prepared ferrites could be adjusted and a proper match was provided between dielectric and magnetic properties by controlling the doped content of Mg{sup 2+}, which would be significant to the application of BaMg{sub x}Co{sub 1−x}TiFe{sub 10}O{sub 19} in the field of the microwave absorbing materials. - Highlights: • The Mg{sup 2+} ions were first employed to occupy the place of Co{sup 2+} ions in BaCoTiFe{sub 10}O{sub 19}. • The grains were refined as Co substitution by Mg in ferrite. • The peaks of complex permeability shift to high frequency with Mg{sup 2+} substituted. • The coercivity increased and saturation magnetization slightly decreased. • Substitution of Mg{sup 2+} enhanced microwave absorption and broadened bandwidth.

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

KAUST Repository

Atanda, Luqman A.

2011-04-01

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

Morphology, magnetic and resonance properties of Fe/MgO multilayers

Energy Technology Data Exchange (ETDEWEB)

Garcia-Garcia, A; Algarabel, P A; Ibarra, M R [Instituto de Ciencia de Materiales de Aragon, Universidad de Zaragoza-CSIC 50009 Zaragoza (Spain); Vovk, A [Centro de Fisica da Materia Condensada Unversidade de Lisboa, Campo Grande Ed. C8, 1749-016, Lisboa (Portugal); Strichovanec, P; Pardo, J A; Magen, C [Instituto de Nanociencia de Aragon, Universidad de Zaragoza 50018 Zaragoza (Spain); Golub, V; Salyuk, O, E-mail: ayvovk@fc.ul.pt [Institute of Magnetism NAS of Ukraine, 36-b Vernnadsky blvd., 03142, Kyiv (Ukraine)

2011-07-06

Magnetic, resonance and transport properties of Fe(t nm)/MgO(3.0 nm) multilayers prepared by pulsed laser deposition were investigated. Comparison of the data allows conclusions on Fe layers morphology. For t<0.61 nm typical features of granular cermet films in dielectric regime are observed, i.e. high electrical resistance, isotropic magnetoresistance and strong temperature dependence of magnetization. For higher t coalescence of Fe granules occurs and metallic percolation cluster is formed at t{approx}0.81 nm. This is manifested by rapid decrease of films resistance and formation of multipeak ferromagnetic resonance spectra. For t>1.25 nm a continuous coverage of MgO by Fe takes place. However, the morphology of Fe layers is rough. This causes the appearance of magnetostatic resonance modes analogous to those observed for continuous films deposited on embossed surfaces.

Nanometric MgFe2O4: Synthesis, characterization and its application towards supercapacitor and electrochemical uric acid sensor

Science.gov (United States)

Majumder, S.; Kumar, S.; Banerjee, S.

2017-05-01

In this paper, we have synthesized nanocrystalline MgFe2O4 (S1) by auto-combustion assisted sol-gel method. The structure and morphology and elemental study of S1 are examined by powder X-ray diffraction (PXRD), field emission scanning electron microscopic (FESEM) and energy dispersive X-ray spectroscopic (EDS) techniques. The FESEM images reveal that the morphology of the sample is rough and average particle size is 50 nm. The PXRD study indicates that the samples are well crystalline and single phase in nature. Moreover, we have performed supercapacitor study by electrochemical galvanostatic charge-discharge (GCD) measurement, which shows pseudo capacitive behavior. S1 contains a high specific capacitance of 428.9 Fg-1 at the current density 0.0625 Ag-1 and can deliver high energy and power density of 18.01 Wh kg-1 and 21468 Wkg-1 respectively. Moreover, uric acid (UA) sensing study has also been performed by cyclic voltmetry (CV) and electrochemical impedance spectroscopy measurement (EIS) of S1. We can use nanocrystalline MgFe2O4 as supercapacitor and UA sensor applications purpose.

Study on adsorption of O{sub 2} on LaFe{sub 1-x}Mg{sub x}O{sub 3} (0 1 0) surface by density function theory calculation

Energy Technology Data Exchange (ETDEWEB)

Liu, Xing, E-mail: liuxing0108@mail.sdu.edu.cn [Civil Engineer Department, Qingdao Technological University (Linyi), Easter Outer Ring Road 1, Linyi, 273400 (China); Cheng, Bin [Civil Engineer Department, Qingdao Technological University (Linyi), Easter Outer Ring Road 1, Linyi, 273400 (China); Hu, Jifan; Qin, Hongwei [State Key Laboratory of Crystal Material, Department of Physics, Shandong University, Hongjialou 5, Jinan, 250100 (China)

2012-09-01

Highlights: Black-Right-Pointing-Pointer Mg-doping can change the electronic properties of LaFeO{sub 3} (0 1 0) surface by decreasing the band gap. Black-Right-Pointing-Pointer The position and content of Mg-doping can both affect the ability to adsorb O{sub 2}. Black-Right-Pointing-Pointer The strong hybridization between O{sub 2} p and Fe d orbital is the origin of binding mechanism. - Abstract: The adsorption of O{sub 2} on the clean and Mg doped LaFeO{sub 3} (0 1 0) surface has been investigated using the density functional theory (DFT) method. Calculation results show that Mg-doping can change the electronic properties of LaFeO{sub 3} (0 1 0) surface by decreasing the band gap. When Mg ions were not on the first layer of the surface, with increasing Mg content the adsorption of O{sub 2} was enhanced. When Mg ions were on the first layer, the adsorption of O{sub 2} was weakened with the increase of Mg content. The analysis results of the DOS indicated that the Mg ion and adsorbed O{sub 2} had no strong hybridization, and the bonding mechanism was originated from the strong hybridization between the O p and Fe d orbital. Referring to all the calculation results, it was found that except for the increase of stability of oxygen adsorption, the Mg doping could not improve the sensitivity to O{sub 2}.

Asymmetric angular dependence of spin-transfer torques in CoFe/Mg-B-O/CoFe magnetic tunnel junctions

Energy Technology Data Exchange (ETDEWEB)

Tang, Ling, E-mail: lingtang@zjut.edu.cn; Xu, Zhi-Jun, E-mail: xzj@zjut.edu.cn; Zuo, Xian-Jun; Yang, Ze-Jin, E-mail: zejinyang@zjut.edu.cn [Department of Applied Physics, College of Science, Zhejiang University of Technology, Hangzhou 310023 (China); Gao, Qing-He [College of Science, Northeastern University, Shenyang 110004, China, Information Engineering College, Liaoning University of Traditional Chinese Medicine, Shenyang 110847 (China); Linghu, Rong-Feng, E-mail: linghu@gznu.edu.cn [School of Physics and Electronics Sciences, Guizhou Education University, Guiyang 550018 (China); Guo, Yun-Dong, E-mail: g308yd@126.com [College of Engineering and Technology, Neijiang Normal University, Neijiang 641112 (China)

2016-04-28

Using a first-principles noncollinear wave-function-matching method, we studied the spin-transfer torques (STTs) in CoFe/Mg-B-O/CoFe(001) magnetic tunnel junctions (MTJs), where three different types of B-doped MgO in the spacer are considered, including B atoms replacing Mg atoms (Mg{sub 3}BO{sub 4}), B atoms replacing O atoms (Mg{sub 4}BO{sub 3}), and B atoms occupying interstitial positions (Mg{sub 4}BO{sub 4}) in MgO. A strong asymmetric angular dependence of STT can be obtained both in ballistic CoFe/Mg{sub 3}BO{sub 4} and CoFe/Mg{sub 4}BO{sub 4} based MTJs, whereas a nearly symmetric STT curve is observed in the junctions based on CoFe/Mg{sub 4}BO{sub 3}. Furthermore, the asymmetry of the angular dependence of STT can be suppressed significantly by the disorder of B distribution. Such skewness of STTs in the CoFe/Mg-B-O/CoFe MTJs could be attributed to the interfacial resonance states induced by the B diffusion into MgO spacer.

Effects of Fe-Enrichment on the Equation of State and Stability of (Mg,Fe)SiO3 Perovskite and Post-Perovskite

Science.gov (United States)

Dorfman, S. M.; Holl, C. M.; Meng, Y.; Prakapenka, V.; Duffy, T. S.

2010-12-01

Fe-enrichment in the deep lower mantle has been proposed as an explanation for seismic anomalies such as large low shear velocity provinces (LLSVPs) and ultralow velocity zones (ULVZs). In order to resolve the effect of Fe on the stability and equation of state of the lower mantle’s dominant constituent, (Mg,Fe)SiO3 perovskite, we have studied Fe-rich natural orthopyroxenes, (Mg0.61Fe0.37Ca0.02)SiO3 and (Mg0.25Fe0.70Ca0.05)SiO3 (compositions determined by microprobe analysis), at lower mantle P-T conditions. Pyroxene starting materials were mixed with Au (pressure calibrant and laser absorber) and loaded with NaCl or Ne (pressure medium and thermal insulator) in a symmetric diamond anvil cell. X-ray diffraction experiments at pressures up to 122 GPa with in-situ laser heating were performed at the GSECARS (13-ID-D) and HPCAT (16-ID-B) sectors of the Advanced Photon Source. Heating samples to 2000 K produced single-phase orthorhombic GdFeO3-type perovskite at 63 GPa for the Mg# 61 composition and at 72 GPa for the Mg# 25 composition. At lower pressures (56 GPa for Mg# 61, 67 GPa for Mg# 25), heating both compositions resulted in a mixture of perovskite, SiO2 and (Mg,Fe)O. These measurements provide new constraints on the dependence of (Mg,Fe)SiO3 perovskite stability on pressure and composition. Upon further compression to 93 GPa and higher pressures with laser heating, Mg# 25 perovskite transformed to a two-phase mixture of perovskite and post-perovskite. This is consistent with previous findings that Fe substitution destabilizes (Mg,Fe)SiO3 perovskite relative to (Mg,Fe)SiO3 post-perovskite (Mao et al. 2004, Caracas and Cohen 2005). The bulk modulus at 80 GPa (K80) is ~550 GPa for both Fe-rich perovskites, comparable to values measured for MgSiO3 perovskite (Lundin et al. 2008). However, the volume of Fe-rich perovskites increases linearly with Fe-content. The (Mg0.25Fe0.70Ca0.05)SiO3 perovskite is 3% greater at 80 GPa than V80 for the Mg end

Microstructure and magnetic properties of FeCo epitaxial thin films grown on MgO single-crystal substrates

International Nuclear Information System (INIS)

Shikada, Kouhei; Ohtake, Mitsuru; Futamoto, Masaaki; Kirino, Fumiyoshi

2009-01-01

FeCo epitaxial films were prepared on MgO(100), MgO(110), and MgO(111) substrates by ultrahigh vacuum molecular beam epitaxy. FeCo thin films with (100), (211), and (110) planes parallel to the substrate surface grow on respective MgO substrates. FeCo/MgO interface structures are studied by high-resolution cross-sectional transmission electron microscopy and the epitaxial growth mechanism is discussed. Atomically sharp boundaries are recognized between the FeCo thin films and the MgO substrates where misfit dislocations are introduced in the FeCo thin films presumably to decrease the lattice misfits. Misfit dislocations are observed approximately every 9 and 1.4 nm in FeCo thin film at the FeCo/MgO(100) and the FeCo/MgO(110) interfaces, respectively. X-ray diffraction analysis indicates that the lattice spacing measured parallel to the single-crystal substrate surfaces are in agreement within 0.1% with those of the respective bulk values of Fe 50 Co 50 alloy crystal, showing that the FeCo film strain is very small. The magnetic anisotropies of these epitaxial films basically reflect the magnetocrystalline anisotropy of bulk FeCo alloy crystal

Synthesis of Mg{sub 2}FeH{sub 6} containing as additives transition metal and transition metal fluorides or carbon; Sintese de Mg{sub 2}FeH{sub 6} contando como aditivos metais de transicao e fluoretos de metais de transicao ou carbono

Energy Technology Data Exchange (ETDEWEB)

Zepon, G.; Leiva, D.R.; Botta, W.J., E-mail: guizepon@yahoo.com.b [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais

2010-07-01

The Mg{sub 2}FeH{sub 6} is a promising way of storing hydrogen in solid form, composed by elements that have low cost and, at the same time, high volumetric storage density: 150 kg H{sub 2}/m{sup 3}. However, this complex hydride is not easily synthesized as a single phase material. The hydrogen sorption high temperature and slow kinetics are the major limitations for the practical application of the Mg{sub 2}FeH{sub 6} as a hydrogen storage material. Little is known about the effects of additives in Mg{sub 2}FeH{sub 6} based nanocomposites in this work were synthesized by MAE under hydrogen atmosphere nanocomposites based on Mg{sub 2}FeH{sub 6} containing additives as transition metals, transition metals fluorides of transition metals or carbon, in order to obtain information on the effects of the selected additives. To this end, we used characterization techniques such as XRD, SEM and TEM, thermal analysis by DSC and curves made in apparatus PCT.(author)

Calcioferrite with composition (Ca3.94Sr0.06Mg1.01(Fe2.93Al1.07(PO46(OH4·12H2O

Directory of Open Access Journals (Sweden)

Barbara Lafuente

2014-03-01

Full Text Available Calcioferrite, ideally Ca4MgFe3+4(PO46(OH4·12H2O (tetracalcium magnesium tetrairon(III hexakis-phosphate tetrahydroxide dodecahydrate, is a member of the calcioferrite group of hydrated calcium phosphate minerals with the general formula Ca4AB4(PO46(OH4·12H2O, where A = Mg, Fe2+, Mn2+ and B = Al, Fe3+. Calcioferrite and the other three known members of the group, montgomeryite (A = Mg, B = Al, kingsmountite (A = Fe2+, B = Al, and zodacite (A = Mn2+, B = Fe3+, usually occur as very small crystals, making their structure refinements by conventional single-crystal X-ray diffraction challenging. This study presents the first structure determination of calcioferrite with composition (Ca3.94Sr0.06Mg1.01(Fe2.93Al1.07(PO46(OH4·12H2O based on single-crystal X-ray diffraction data collected from a natural sample from the Moculta quarry in Angaston, Australia. Calcioferrite is isostructural with montgomeryite, the only member of the group with a reported structure. The calcioferrite structure is characterized by (Fe/AlO6 octahedra (site symmetries 2 and -1 sharing corners (OH to form chains running parallel to [101]. These chains are linked together by PO4 tetrahedra (site symmetries 2 and 1, forming [(Fe/Al3(PO43(OH2] layers stacking along [010], which are connected by (Ca/Sr2+ cations (site symmetry 2 and Mg2+ cations (site symmetry 2; half-occupation. Hydrogen-bonding interactions involving the water molecules (one of which is equally disordered over two positions and OH function are also present between these layers. The relatively weaker bonds between the layers account for the cleavage of the mineral parallel to (010.

Microstructural evolution during hydrogen sorption cycling of Mg-FeTi nanolayered composites

Energy Technology Data Exchange (ETDEWEB)

Kalisvaart, W.P., E-mail: pkalisvaart@gmail.com [Chemical and Materials Engineering, University of Alberta and National Research Council Canada, National Institute for Nanotechnology, Edmonton, AB, T6G 2V4 (Canada); Kubis, Alan; Danaie, Mohsen; Amirkhiz, Babak Shalchi [Chemical and Materials Engineering, University of Alberta and National Research Council Canada, National Institute for Nanotechnology, Edmonton, AB, T6G 2V4 (Canada); Mitlin, David, E-mail: dmitlin@ualberta.ca [Chemical and Materials Engineering, University of Alberta and National Research Council Canada, National Institute for Nanotechnology, Edmonton, AB, T6G 2V4 (Canada)

2011-03-15

This paper describes the microstructural evolution of Mg-FeTi mutlilayered hydrogen storage materials during extended cycling. A 28 nm Mg-5 nm FeTi multilayer has comparable performance to a cosputtered material with an equivalent composition (Mg-10%Fe-10%Ti), which is included as a baseline case. At 200 deg. C, the FeTi layers act as a barrier, preventing agglomeration of Mg particles. At 300 deg. C, the initial structure of the multilayer is preserved up to 35 cycles, followed by fracturing of the Mg layers in the in-plane direction and progressive delamination of the FeTi layers as observed by electron microscopy. Concurrently, an increase in the Mg grain size was observed from 32 to 76 nm between cycles 35 and 300. As a result, the absorption kinetics deteriorate with cycling, although 90% of the total capacity is still absorbed within 2 min after as many as 300 cycles. The desorption kinetics, on the other hand, remain rapid and stable, and complete desorption of 4.6 wt.% H is achieved in 1.5 min at ambient desorption pressure. In addition to showing good hydrogen storage performance, multilayers are an excellent model system for studying the relation between microstructure and hydrogen absorption/desorption kinetics.

Microstructural evolution during hydrogen sorption cycling of Mg-FeTi nanolayered composites

International Nuclear Information System (INIS)

Kalisvaart, W.P.; Kubis, Alan; Danaie, Mohsen; Amirkhiz, Babak Shalchi; Mitlin, David

2011-01-01

This paper describes the microstructural evolution of Mg-FeTi mutlilayered hydrogen storage materials during extended cycling. A 28 nm Mg-5 nm FeTi multilayer has comparable performance to a cosputtered material with an equivalent composition (Mg-10%Fe-10%Ti), which is included as a baseline case. At 200 deg. C, the FeTi layers act as a barrier, preventing agglomeration of Mg particles. At 300 deg. C, the initial structure of the multilayer is preserved up to 35 cycles, followed by fracturing of the Mg layers in the in-plane direction and progressive delamination of the FeTi layers as observed by electron microscopy. Concurrently, an increase in the Mg grain size was observed from 32 to 76 nm between cycles 35 and 300. As a result, the absorption kinetics deteriorate with cycling, although 90% of the total capacity is still absorbed within 2 min after as many as 300 cycles. The desorption kinetics, on the other hand, remain rapid and stable, and complete desorption of 4.6 wt.% H is achieved in 1.5 min at ambient desorption pressure. In addition to showing good hydrogen storage performance, multilayers are an excellent model system for studying the relation between microstructure and hydrogen absorption/desorption kinetics.

Mg shallow doping effects on the ac magnetic self-heating characteristics of γ-Fe2O3 superparamagnetic nanoparticles for highly efficient hyperthermia

Science.gov (United States)

Jang, Jung-tak; Bae, Seongtae

2017-10-01

The effects of Mg doping on the magnetic and AC self-heating temperature rising characteristics of γ-Fe2O3 superparamagnetic nanoparticles (SPNPs) were investigated for hyperthermia applications in biomedicine. The doping concentration of nonmagnetic Mg2+ cation was systematically controlled from 0 to 0.15 at. % in Mgx-γFe2O3 SPNPs during chemically and thermally modified one-pot thermal decomposition synthesis under bubbling O2/Ar gas mixture. It was empirically observed that the saturation magnetization (Ms) and the out-of-phase magnetic susceptibility ( χm″)of Mgx-γFe2O3 SPNPs were increased by increasing the Mg2+ cation doping concentration from 0.05 to 0.13 at. %. Correspondingly, the AC magnetically induced self-heating temperature (Tac,max) in solid state and the intrinsic loss power in water were increased up to 184 °C and 14.2 nH m2 kg-1 (Mgx-γFe2O3, x = 0.13), respectively, at the biologically and physiologically safe range of AC magnetic field (Happl × fappl = 1.2 × 109 A m-1 s-1). All the chemically and physically analyzed results confirmed that the dramatically improved AC magnetic induction heating characteristics and the magnetic properties of Mgx-γFe2O3 SPNPs (x = 0.13) are primarily due to the significantly enhanced magnetic susceptibility (particularly, χm″) and the improved AC/DC magnetic softness (lower AC/DC magnetic anisotropy) resulting from the systematically controlled nonmagnetic Mg2+ cation concentrations and distributions (occupation ratio) in the Fe vacancy sites of γ-Fe2O3 (approximately 12% vacancy), instead of typically well-known Fe3O4 (no vacancy) SPNPs. The cell viability and biocompatibility with U87 MG cell lines demonstrated that Mgx-γFe2O3 SPNPs (x = 0.13) has promising bio-feasibility for hyperthermia agent applications.

A study on magneto-optic properties of CoxMg1-xFe2O4 nanoferrofluids

Science.gov (United States)

Karthick, R.; Ramachandran, K.; Srinivasan, R.

2018-04-01

Nanoparticles of CoxMg1-xFe2O4 (x = 0.1, 0.5, 0.9) were synthesized using chemical co-precipitation method. Characterization by X-ray diffraction technique confirmed the formation of cubic crystalline structure and the crystallite size of the samples obtained using Debye-Scherrer approximation were found to increase with increasing cobalt substitution. Surface morphology and the Chemical composition of the samples were visualized using scanning electron microscope (SEM) with energy dispersive analysis of X-rays (EDAX). Room temperature magnetic parameters of the nanoparticles by vibrating sample magnetometer (VSM) revealed the magnetic properties such as Saturation magnetization (Ms), Remanent magnetization (Mr) and Coercive field (Hc) found to increase with increasing cobalt substitution. Faraday rotation measurements on CoxMg1-xFe2O4 ferrofluids exhibited increase in rotation with cobalt substitution. Further, there is an increase in Faraday rotation with increasing magnetic field for all the samples.

THE LICK/SDSS LIBRARY. II. [Ca/Fe] AND [Mg/Fe] IN F, G, AND K STARS FROM SDSS-DR7

International Nuclear Information System (INIS)

Franchini, M.; Morossi, C.; Di Marcantonio, P.; Malagnini, M. L.; Chavez, M.

2011-01-01

We analyzed the spectra of 17,600 F, G, and K stars extracted from the seventh Sloan Digital Sky Survey Data Release (SDSS-DR7) database in order to derive ([α/Fe]), [Ca/Fe], and [Mg/Fe] ratios. Particular attention has been devoted to estimating homogeneous and self-consistent atmospheric parameter values, T eff , log g, and [Fe/H], by comparing synthetic and observational Lick/SDSS indices. We present results for the sub-sample of more than 4000 spectra whose overall quality allowed us to derive fairly accurate stellar atmospheric parameter values and, therefore, reliable abundance ratios. A Monte Carlo approach was adopted to evaluate both the errors in the observational Lick/SDSS indices and in the derived parameter estimates. The analysis of the trends of [Ca/Fe] and [Mg/Fe] versus [Fe/H] pointed out that (1) the [Ca/Fe] and [Mg/Fe] ratios increase with decreasing [Fe/H] with different slopes reaching maximum average levels of +0.25 and +0.40 dex at [Fe/H] ≅ -1.75, respectively; (2) our sample contains, at a given [Fe/H], stars characterized by significantly different amounts of α-enhancement, thus belonging to different Galactic populations; and (3) the analyzed sample shows a predominance of thick disk stars for [Fe/H] > - 0.5 and the presence of stars belonging to the h igh-αhalo population for -2.0 < [Fe/H] <-0.5.

Crystal structure of a Ce2Fe2Mg15 compound

International Nuclear Information System (INIS)

Opainich, I.M.; Pavlyuk, V.V.; Bodak, O.I.

1996-01-01

A structure of a new Ce2Fe2Mg15 ternary compound (P63/mmc sp.gr., a=1.0324(5) nm, c=1.02080(4) nm) was determined by powder methods on a DRON-4.07 automatic diffractometer. The structure of a Ce2Fe2Mg15 crystal is a new variant of the ordered Th2Ni17 type superstructure, in which cerium atoms occupy the thorium positions; magnesium atoms occupy the nickel position 6g, 12k, and 12j; and iron atoms occupy the 4f position

Behavior of methyl orange and orange 10 (orange G) in the presence of hydrotalcite type compounds of Mg/Al and Mg/Fe

International Nuclear Information System (INIS)

Cruz N, G.

2015-01-01

This work is focused on studying the sorption capacity of methyl orange dye (Nm) and orange 10 (N-10) in the presence of hydrotalcite type compounds of Mg/Al and Mg/Fe uncalcined and calcined previously at 500 degrees Celsius. Sorption isotherms were determined and the study of the kinetics of sorption was performed. The materials were characterized before and after sorption processes of these dyes by X-ray diffraction, scanning electron microscopy, the specific surface area determination by the Brunauer-Emmett-Teller method, thermogravimetry coupled to mass and infrared spectrometry. The hydrotalcite type compounds reported in this paper were prepared in the laboratory and their acronyms are: HTMgAlG1, HTMgAlMO, HTMgFeG1 and HTMgFeG2. Note that in this work the best conditions for preparing compounds of Mg/Fe were found. From patterns of X-ray diffraction was identified the typical crystal structure of the hydrotalcite type compounds. By scanning electron microscopy the morphology could be determined in the form of flakes characteristics of these compounds. Likewise with elemental analysis of energy dispersive X-ray spectroscopy the presence of Mg, Al, Fe and C, elements of interest for this study was determined. The compounds presented a specific surface area relatively high from 80 to 120 m 2 /g. Thermogravimetry results presented spectra of mass loss very characteristic associated to water losses, dehydroxylation and decarboxylation. The characteristic bands of water and carbonate were assigned by infrared spectroscopy and the bands corresponding to the dyes sulfonates were identified only for the calcined materials. The sorption capacities found of these compounds were as follows: for Nm in the compound HTMgAlG1 uncalcined was 17.82 mg/g for an initial concentration of 200 mg/L and for calcined (HTMgAlMOcal) of 99.8 mg/g with and initial concentration of 1000 mg/L. Moreover, the sorption capacity of the dye N-10 in this same material was 17.92 mg/g and 99.4 mg

Spin-polarized electron tunneling in bcc FeCo/MgO/FeCo(001) magnetic tunnel junctions.

Science.gov (United States)

Bonell, F; Hauet, T; Andrieu, S; Bertran, F; Le Fèvre, P; Calmels, L; Tejeda, A; Montaigne, F; Warot-Fonrose, B; Belhadji, B; Nicolaou, A; Taleb-Ibrahimi, A

2012-04-27

In combining spin- and symmetry-resolved photoemission, magnetotransport measurements and ab initio calculations we detangled the electronic states involved in the electronic transport in Fe(1-x)Co(x)(001)/MgO/Fe(1-x)Co(x)(001) magnetic tunnel junctions. Contrary to previous theoretical predictions, we observe a large reduction in TMR (from 530 to 200% at 20 K) for Co content above 25 atomic% as well as anomalies in the conductance curves. We demonstrate that these unexpected behaviors originate from a minority spin state with Δ(1) symmetry that exists below the Fermi level for high Co concentration. Using angle-resolved photoemission, this state is shown to be a two-dimensional state that occurs at both Fe(1-x)Co(x)(001) free surface, and more importantly at the interface with MgO. The combination of this interface state with the peculiar density of empty states due to chemical disorder allows us to describe in details the complex conduction behavior in this system.

Mg2FeH6 Synthesis Efficiency Map

Directory of Open Access Journals (Sweden)

Katarzyna Witek

2018-02-01

Full Text Available The influences of the processing parameters on the Mg2FeH6 synthesis yield were studied. Mixtures of magnesium hydride (MgH2 and iron (Fe were mechanically milled in a planetary ball mill under argon for 0.5-, 1-, 2- and 3-h periods and subsequently sintered at temperatures from 300–500 ∘ C under hydrogen. The reaction yield, phase content and hydrogen storage properties of the received materials were investigated. The morphologies of the powders after synthesis were studied by SEM. The synthesis effectiveness map was presented. The obtained results prove that synthesis parameters, such as the milling time and synthesis temperature, greatly influence the reaction yield and material properties and show that extended mechanical milling may not be beneficial to the reaction efficiency.

Postoperative impairment of motor function at train-of-four ratio ≥0.9 cannot be improved by sugammadex (1 mg kg-1).

Science.gov (United States)

Baumüller, E; Schaller, S J; Chiquito Lama, Y; Frick, C G; Bauhofer, T; Eikermann, M; Fink, H; Blobner, M

2015-05-01

A train-of-four ratio (TOFR) ≥0.9 measured by quantitative neuromuscular monitoring is accepted as an indication of sufficient neuromuscular recovery for extubation, even though many postsynaptic acetylcholine receptors may still be inhibited. We investigated whether antagonism with sugammadex after spontaneous recovery to TOFR≥0.9 further improves muscle function or subjective well-being. Following recovery to TOFR≥0.9 and emergence from anaesthesia, 300 patients randomly received either sugammadex 1.0 mg kg(-1) or placebo. Fine motor function (Purdue Pegboard Test) and maximal voluntary grip strength were measured before and after surgery (before and after test drug administration). At discharge from the postanaesthesia care unit, well-being was assessed with numerical analogue scales and the Quality-of-Recovery Score 40 (QoR-40). Patients' fine motor function [6 (sd 4) vs 15 (3) pegs (30 s)(-1), Psugammadex or placebo, motor function was significantly improved in both groups but did not reach the preoperative level. There was no difference between groups at any time. Global well-being was unaffected (QoR-40: placebo, 174 vs 185; sugammadex, 175 vs 186, P>0.05). Antagonizing rocuronium at TOF≥0.9 with sugammadex 1.0 mg kg(-) (1) did not improve patients' motor function or well-being when compared with placebo. Our data support the view that TOFR≥0.9 measured by electromyography signifies sufficient recovery of neuromuscular function. The trial is registered at ClinicalTrials.gov (NCT01101139). © The Author 2014. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Raman study of cations’ distribution in ZnxMg1−xFe2O4 nanoparticles

International Nuclear Information System (INIS)

Silva, S. W. da; Nakagomi, F.; Silva, M. S.; Franco, A.; Garg, V. K.; Oliveira, A. C.; Morais, P. C.

2012-01-01

In a complementary way, Raman and Mössbauer spectroscopy were successfully employed to assess the cations’ distribution among the tetrahedral (A-site) and octahedral (B-site) sites of nonosized Zn x Mg 1−x Fe 2 O 4 (0 ≤ x ≤ 1) cubic ferrite structure, synthesized by combustion reaction method. Nanoparticles with little change in size distributions, in the 40 nm (x = 0.0) up to 42 nm (x = 1.0) were obtained. Mössbauer data indicated that as the Zn-content (x) increases in the range 0 ≤ x ≤ 1, the Fe 3+ ion monotonically increases (decreases) the A-site (B-site) occupancy up to nearly equal values at the highest end x value. Analysis of the Raman data, however, confirms that the three highest energy modes around 650, 668 and 710 cm −1 are assigned to Zn–O (B-site), Fe–O (A-site) and Mg–O (A-site) vibrations, respectively. Additionally, in agreement with the Mössbauer data, the Raman data show that as the Zn-content (x) increases in the range 0 ≤ x ≤ 1, the occupancy of A-sites by Mg 2+ ions monotonically reduces with concomitant increase of A- and B-sites occupancy by Fe 3+ and Zn 2+ ions, respectively. Indeed, combination of the two sets of spectroscopic data (Raman and Mössbauer) provides an effective protocol for assessing the cations’ distribution within the crystal structure of nanosized quaternary cubic ferrite samples.

Ethylbenzene dehydrogenation over binary FeOx–MeOy/Mg(Al)O catalysts derived from hydrotalcites

KAUST Repository

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

2010-01-01

A series of FeOx-MeOy/Mg(Al)O catalysts were prepared from hydrotalcite-like compounds as precursors and were tested in the ethylbenzene dehydrogenation to styrene in He atmosphere at 550 °C. The hydrotalcite-like precursors of the metal compositions of Mg3Fe 0.25Me0.25Al0.5 (Me = Cu, Zn, Cr, Mn, Fe, Co and Ni) were coprecipitated from the nitrates of metal components and calcined to mixed oxides at 550 °C. After the calcination, the mixed oxides showed high surface area of 150-200 m2 gcat -1, and were mainly composed of (MgMe)(Fe3+Al)O periclase in the bulk, whereas the surface was enriched by (MgMe)(Fe3+Al)2O 4 pinel. Among the Me species tested, Co2+ was the most effective, followed by Ni2+. Co2+ addition increased the activity of original FeOx/Mg(Al)O catalyst, whereas Ni2+ increased the activity at the beginning of reaction, but deactivated the catalyst during the reaction. The other metals formed isolated MeOx species in the catalyst, resulting in a decrease in the activity compared to the original FeOx/Mg(Al)O catalyst. The active Fe species exists as metastable Fe3+ on the FeOx/Mg(Al)O catalyst. By the addition of Co2+, the reduction-oxidation between Fe3+ and Fe2+ was facilitated and, moreover, the active Fe3+ species was stabilized. It is likely that the dehydrogenation proceeds on the active Fe3+ species via its reduction-oxidation assisted by Co 2+. © 2010 Elsevier B.V.

Ethylbenzene dehydrogenation over binary FeOx–MeOy/Mg(Al)O catalysts derived from hydrotalcites

KAUST Repository

Balasamy, Rabindran J.

2010-12-20

A series of FeOx-MeOy/Mg(Al)O catalysts were prepared from hydrotalcite-like compounds as precursors and were tested in the ethylbenzene dehydrogenation to styrene in He atmosphere at 550 °C. The hydrotalcite-like precursors of the metal compositions of Mg3Fe 0.25Me0.25Al0.5 (Me = Cu, Zn, Cr, Mn, Fe, Co and Ni) were coprecipitated from the nitrates of metal components and calcined to mixed oxides at 550 °C. After the calcination, the mixed oxides showed high surface area of 150-200 m2 gcat -1, and were mainly composed of (MgMe)(Fe3+Al)O periclase in the bulk, whereas the surface was enriched by (MgMe)(Fe3+Al)2O 4 pinel. Among the Me species tested, Co2+ was the most effective, followed by Ni2+. Co2+ addition increased the activity of original FeOx/Mg(Al)O catalyst, whereas Ni2+ increased the activity at the beginning of reaction, but deactivated the catalyst during the reaction. The other metals formed isolated MeOx species in the catalyst, resulting in a decrease in the activity compared to the original FeOx/Mg(Al)O catalyst. The active Fe species exists as metastable Fe3+ on the FeOx/Mg(Al)O catalyst. By the addition of Co2+, the reduction-oxidation between Fe3+ and Fe2+ was facilitated and, moreover, the active Fe3+ species was stabilized. It is likely that the dehydrogenation proceeds on the active Fe3+ species via its reduction-oxidation assisted by Co 2+. © 2010 Elsevier B.V.

Effect of film roughness in Fe/MgO/Fe magnetic tunnel junctions: model calculations

Energy Technology Data Exchange (ETDEWEB)

Edalati Boostan, Saeideh; Heiliger, Christian [I. Physikalisches Institut, Justus Liebig University Giessen, D-35392 (Germany); Moradi, Hosein [Department of Physics,Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of)

2011-07-01

We calculate how interface roughness affects the tunneling magnetoresistance (TMR) in Fe/MgO/Fe (100) junctions. The used method is based on a single-band tight-binding (SBTB) approximation employing the Green's function formalism. We investigate the influence of disorder at the TMR ratio. Thereby, the disorder is modeled by considering different occupation probabilities of Fe and MgO at interface sites. We calculate the current densities for parallel and anti-parallel configurations for different disorders. The results show that the roughness decreases the TMR that match well with experimental observations.

Final report of AFRIMETS.M.M-S6: supplementary comparison of 100 mg, 100 g 500 g, 1 kg and 5 kg stainless steel mass standards

Science.gov (United States)

Mautjana, R. T.; Molefe, P. T.; Mayindu, N. F.; Armah, M. N.; Ramasawmy, V.; Albasini, G. L.; Matali, S.; Richmond, H.; Rusimbi, V.; Kiwanuka, J.; Mutale, D. M.; Mutsimba, F.

2018-01-01

This report summarizes the results of AFRIMETS.M.M-S6 mass standards comparison conducted between eleven participating laboratories/countries. Two sets of five weights with nominal values 100 mg, 100 g, 500 g, 1 kg and 5 kg were used as the traveling standards. These nominal values were decided from the needs of participating laboratories submitted to the pilot laboratory through a questionnaire and agreed upon by all participants. The traveling standards were hand carried between laboratories starting from February 2014 and were received from the last participants in October 2014. The programme was coordinated by National Metrology Institute of South Africa (NMISA), who provided the travelling standards and reference values for the comparison. The corrections to the BIPM as-maintained mass unit [5] have insignificant influence on the results of this comparison. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Concentrations in plasma, epithelial lining fluid, alveolar macrophages and bronchial mucosa after a single intravenous dose of 1.6 mg/kg of iclaprim (AR-100) in healthy men.

Science.gov (United States)

Andrews, J; Honeybourne, D; Ashby, J; Jevons, G; Fraise, A; Fry, P; Warrington, S; Hawser, S; Wise, R

2007-09-01

A validated microbiological assay was used to measure concentrations of iclaprim (AR-100) in plasma, bronchial mucosa (BM), alveolar macrophages (AM) and epithelial lining fluid (ELF) after a single 1.6 mg/kg intravenous 60 min iv infusion of iclaprim. Male volunteers were randomly allocated to three nominal sampling time intervals 1-2 h (Group A), 3-4 h (Group B) and 5.5-7.0 h (Group C) after the start of the drug infusion. Mean iclaprim concentrations in plasma, BM, AM and ELF, respectively, were for Group A 0.59 mg/L (SD 0.18), 0.51 mg/kg (SD 0.17), 24.51 mg/L (SD 21.22) and 12.61 mg/L (SD 7.33); Group B 0.24 mg/L (SD 0.05), 0.35 mg/kg (SD 0.17), 7.16 mg/L (SD 1.91) and 6.38 mg/L (SD 5.17); and Group C 0.14 mg/L (SD 0.05), no detectable level in BM, 5.28 mg/L (SD 2.30) and 2.66 mg/L (SD 2.08). Iclaprim concentrations in ELF and AM exceeded the MIC(90) for penicillin-susceptible Streptococcus pneumoniae (MIC90 0.06 mg/L), penicillin-intermediate S. pneumoniae (MIC90 2 mg/L), penicillin-resistant S. pneumoniae (MIC90 4 mg/L) for 7, 7 and 4 h, respectively, and Chlamydia pneumoniae (MIC90 0.5 mg/L) for 7 h. Mean iclaprim concentrations in ELF exceeded the MIC90 for Haemophilus influenzae (MIC90 4 mg/L) and Moraxella catarrhalis (MIC90 8 mg/L) for up to 4 and 2 h, respectively; in AM the MIC90 was exceeded for up to 7 h. Furthermore, the MIC90 for methicillin-resistant Staphylococcus aureus of 0.12 mg/L was exceeded at all sites for up to 7 h. These data suggest that iclaprim reaches lung concentrations that should be effective in the treatment of community-acquired pneumonia.

Uncertainty estimation of analysis of Fe, Ca, Zr, Ba, La, Ti and Ce in sediment sample using XRF method

International Nuclear Information System (INIS)

Sukirno; Agus Taftazani

2010-01-01

An uncertainty of analysis of Fe, Ca, Zr, Ba, La, Ti and Ce in river sediment of Panfuran Wariness sample by X RF method has been done. The result value of testing is meaningless if it isn't completed without uncertainty value. The calculation of Ba metal have been presented for example. The aim of the research is to get accreditation certificate of X-Ray Fluorescence method on laboratory of analytical PTAPB – BATAN as well as ISO guide 17025-2005. The result of calculation uncertainty of Fe, Zr, Ba, La, Ce, Ti and Ca analysis showed that the uncertainty components come from: preparation of sample and standard/comparator, purity of material, counting statistic (sample and standard ) and repeatability. The results showed that metals in river sediment of Pancuran Wonosari were Fe = 7.290%, Zr = 54.5 mg/kg, Ba = 1661.6 mg/kg, La = 22.9 mg/kg, Ce = 161.0 mg/kg, Ti = 3193.2 and Ca = 7.816%, and the result of uncertainty estimate of Fe, Zr, Ba, La, Ce, Ti and Ca were ± 0.60%, ± 4.5 mg/kg, ± 55 mg/kg, ± 1.4 mg/kg, 12.0 mg/kg, ± 208 mg/kg and ± 0.61%. (author)

Mössbauer and magnetic studies of Mg{sub 1+2x}Sb{sub x}Fe{sub 2−3x}O{sub 4} spinel ferrites

Energy Technology Data Exchange (ETDEWEB)

Widatallah, H.M., E-mail: hishammw@squ.edu.om [Department of Physics, College of Science, Sultan Qaboos University, 123 Muscat (Oman); Al-Mamari, F.A.S.; Al-Saqri, N.A.M.; Gismelseed, A.M.; Al-Omari, I.A.; Al-Shahumi, T.M.H. [Department of Physics, College of Science, Sultan Qaboos University, 123 Muscat (Oman); Alhaj, A.F. [Department of Physics, Qasim University, Al-Qasim (Saudi Arabia); Abo El Ata, A.M. [Department of Physics, Faculty of Science, Tanta University, Tanta (Egypt); Elzain, M.E. [Department of Physics, College of Science, Sultan Qaboos University, 123 Muscat (Oman)

2013-06-15

Spinel-related Mg{sub 1+2x}Sb{sub x}Fe{sub 2−3x}O{sub 4} samples (x = 0.0, 0.05, 0.10, 0.15, 0.20, and 0.30) prepared using the conventional double sintering technique were investigated using {sup 57}Fe Mössbauer spectroscopy and magnetic measurements. Mössbauer spectra favor a cationic distribution of the form (Mg{sub δ}Fe{sub 1−δ}){sup A}[Mg{sub 1+2x−δ}Sb{sub x}Fe{sub 1+δ−3x}]{sup B}O{sub 4} among the tetrahedral-A and octahedral-B sites of the spinel structure. The cation distribution parameter (δ) was found to vary with the Sb{sup 5+} concentration (x). The Mössbauer hyperfine magnetic fields at both sites and the Curie temperatures of the ferrites decrease as x increases. This was attributed to gradual weakening in the magnetic exchange interaction as more Fe{sup 3+} ions are substituted by diamagnetic Sb{sup 5+} and Mg{sup 2+} ones. The sample with x = 0.30 exhibits short range magnetic order due to cationic clustering and/or superparamagnetism. The magnetization of all samples was found to be temperature-dependent implying that δ depends on temperature in addition to x. At low temperatures the substituted ferrites (x ≠ 0.0) unexpectedly exhibit higher magnetization values relative to that of the pure ferrite MgFe{sub 2}O{sub 4}. This behavior, while at variance with the Néel's model for ferrimagnetism, is explicable in terms of the spin canting mechanism proposed in the Yafet–Kittel model. - Highlights: ► A Mössbauer and magnetic study of Sb{sup 5+} and Mg{sup 2+} co-substituted ferrites of the composition Mg{sub 1+2x}Sb{sub x}Fe{sub 2−3x}O{sub 4} is reported. ► The cation distribution in Mg{sub 1+2x}Sb{sub x}Fe{sub 2−3x}O{sub 4} is shown to depend on both the Sb{sup 5+} ionic concentration and the temperature. ► The A–B magnetic exchange interaction and Mössbauer hyperfine fields weaken with increasing Sb{sup 5+} and Mg{sup 2+} concentrations. ► The magnetization of the substituted samples with x ≠ 0.00 increases

Study of interlayer coupling between FePt and FeCoB thin films through MgO spacer layer

Science.gov (United States)

Singh, Sadhana; Kumar, Dileep; Gupta, Mukul; Reddy, V. Raghvendra

2017-05-01

Interlayer exchange coupling between hard-FePt and soft-FeCoB magnetic layers has been studied with increasing thickness of insulator MgO spacer layer in FePt/MgO/FeCoB sandwiched structure. A series of the samples were prepared in identical condition using ion beam sputtering method and characterized for their magnetic and structural properties using magneto-optical Kerr effect (MOKE) and X-ray reflectivity measurements. The nature of coupling between FePt and FeCoB was found to be ferromagnetic which decreases exponentially with increasing thickness of MgO layer. At very low thickness of MgO layer, both layers were found strongly coupled thus exhibiting coherent magnetization reversal. At higher thickness, both layers were found decoupled and magnetization reversal occurred at different switching fields. Strong coupling at very low thickness is attributed to pin holes in MgO layer which lead to direct coupling whereas on increasing thickness, coupling may arise due to magneto-static interactions.

Orientation and magnetic properties of FePt and CoPt films grown on MgO(1 1 0) single-crystal substrate by electron-beam coevaporation

Energy Technology Data Exchange (ETDEWEB)

Yu Minghui [Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742 (United States); Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148 (United States)], E-mail: myu1@uno.edu; Ohguchi, H.; Zambano, A.; Takeuchi, I. [Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742 (United States); Liu, J.P. [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Josell, D.; Bendersky, L.A. [Metallurgy Division, Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States)

2007-09-25

We have studied the orientation and magnetic properties of FePt and CoPt films deposited by electron-beam co-evaporation on MgO(1 1 0) single-crystal substrates at substrate temperatures from 500 to 700 deg. C. We observed that long-range chemical ordering of the L1{sub 0} structure occurred over the entire range of substrate temperatures in FePt films and at 600 deg. C and up in CoPt films. Growth of FePt and CoPt yielded epitaxial films with cube-on-cube orientation of the pseudo-cubic L1{sub 0} lattice with respect to the cubic MgO. X-ray diffraction patterns and magnetization loops of the FePt and CoPt films revealed the existence of L1{sub 0} domains with the tetragonal c axis inclined at 45 deg. to the film plane, orientations (0 h h) and (h 0 h), as well as L1{sub 0} domains with the tetragonal c axis in the plane of the film, orientation (h h 0). The FePt and CoPt films for which X-ray diffraction indicated tetragonal phase was present all exhibited hard magnetic properties with easy axis along the [0 0 1] substrate direction as well as large in-plane magnetocrystalline anisotropy.

Induction heating studies of combustion synthesized MgFe2O4 nanoparticles for hyperthermia applications

International Nuclear Information System (INIS)

Khot, V.M.; Salunkhe, A.B.; Thorat, N.D.; Phadatare, M.R.; Pawar, S.H.

2013-01-01

The structural, magnetic and ac magnetically induced heating characteristics of combustion synthesized MgFe 2 O 4 nanoparticles have been investigated for application in magnetic particle hyperthermia. As prepared nanoparticles showed ferrimagnetic behavior at room temperature with magnetization of about 33.83 emu/g at ±15 kOe. The solid state MgFe 2 O 4 nanoparticles exhibited specific absorption rate (SAR) of about 297 W/g at physiological safe range of frequency and amplitude. The increase in SAR and heating temperature in ac magnetic field was thought to be due to enhancement in magnetic hysteresis loss caused by dipole–dipole interactions in combustion synthesized MgFe 2 O 4 nanoparticles. - Highlights: ► Highly crystalline pure MgFe 2 O 4 nanoparticles were synthesized by low temperature combustion. ► Effect of ac magnetic field and nanoparticles concentration on heating characteristics of MgFe 2 O 4 nanoparticles was studied. ► Combustion synthesized MgFe 2 O 4 nanoparticles show highest specific absorption rate of 297 Wg −1 . ► The reported high value of specific absorption rate is advantageous for its use in magnetic particle hyperthermia

Controllable synthesis of carbon nanotubes by changing the Mo content in bimetallic Fe-Mo/MgO catalyst

International Nuclear Information System (INIS)

Xu Xiangju; Huang Shaoming; Yang Zhi; Zou Chao; Jiang Junfan; Shang Zhijie

2011-01-01

Research highlights: → Increasing the Mo content in the Fe-Mo/MgO catalysts resulted in an increase in wall number, diameter and growth yield of carbon nanotubes. → The Fe interacts with MgO to form complex (MgO) x (FeO) 1-x (0 4 and relative large metal Mo particles can be generated after reduction. → The avalanche-like reduction of MgMoO 4 makes the catalyst particles to be small thus enhances the utilize efficiency of Fe nanoparticles. - Abstract: A series of Fe-Mo/MgO catalysts with different Mo content were prepared by combustion method and used as catalysts for carbon nanotube (CNT) growth. Transmission electron microscopy studies of the nanotubes show that the number of the CNT walls and the CNT diameters increase with the increasing of Mo content in the bimetallic catalyst. The growth yield determined by thermogravimetric analysis also follows the trend: the higher the Mo content, the higher the yield of the CNTs. However, the increase of Mo content leads to the lower degree of graphitization of CNTs. A comparative study on the morphology and catalytic functions of Fe/MgO, Mo/MgO and Fe-Mo/MgO catalysts was carried out by scanning electron microscopy and X-ray diffraction. It is found that the Fe interacts with MgO to form complexes and is then dispersed into the MgO support uniformly, resulting in very small Fe nanoparticles after reduction. The Mo interacts with MgO to form stoichiometry compound MgMoO 4 and relative large metal Mo particles can be generated after reduction. High yield CNTs with small diameter can be generated from Fe-Mo/MgO because the avalanche-like reduction of MgMoO 4 makes the catalyst particles to be small thus enhances the utilize efficiency of Fe nanoparticles.

The Adsorption of Dextranase onto Mg/Fe-Layered Double Hydroxide: Insight into the Immobilization

Directory of Open Access Journals (Sweden)

Yi Ding

2018-03-01

Full Text Available We report the adsorption of dextranase on a Mg/Fe-layered double hydroxide (Mg/Fe-LDH. We focused the effects of different buffers, pH, and amino acids. The Mg/Fe-LDH was synthesized, and adsorption experiments were performed to investigate the effects. The maximum adsorption occurred in pH 7.0 4-(2-hydroxyethyl-1-piperazineethanesulfonic acid (HEPES buffer, and the maximum dextranase adsorption uptake was 1.38 mg/g (416.67 U/mg; histidine and phenylalanine could affect the adsorption. A histidine tag could be added to the protein to increase the adsorption significantly. The performance features and mechanism were investigated with X-ray diffraction patterns (XRD and Fourier transform infrared spectra (FTIR. The protein could affect the crystal structure of LDH, and the enzyme was adsorbed on the LDH surface. The main interactions between the protein and LDH were electrostatic and hydrophobic. Histidine and phenylalanine could significantly affect the adsorption. The hexagonal morphology of LDH was not affected after adsorption.

In-situ grazing incidence X-ray diffraction measurements of relaxation in Fe/MgO/Fe epitaxial magnetic tunnel junctions during annealing

Energy Technology Data Exchange (ETDEWEB)

Eastwood, D.S. [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Ali, M.; Hickey, B.J. [Department of Physics and Astronomy, University of Leeds, Leeds LS2 1JT (United Kingdom); Tanner, B.K., E-mail: b.k.tanner@dur.ac.uk [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom)

2013-12-15

The relaxation of Fe/MgO/Fe tunnel junctions grown epitaxially on (001) MgO substrates has been measured by in-situ grazing incidence in-plane X-ray diffraction during the thermal annealing cycle. We find that the Fe layers are fully relaxed and that there are no irreversible changes during annealing. The MgO tunnel barrier is initially strained towards the Fe but on annealing, relaxes and expands towards the bulk MgO value. The strain dispersion is reduced in the MgO by about 40% above 480 K post-annealing. There is no significant change in the “twist” mosaic. Our results indicate that the final annealing stage of device fabrication, crucial to attainment of high TMR, induces substantial strain relaxation at the MgO barrier/lower Fe electrode interface. - Highlights: • Lattice relaxation of Fe/MgO/Fe epitaxial magnetic tunnel junctions measured. • In-plane lattice parameter of Fe equal to bulk value; totally relaxed. • MgO barrier initially strained towards the Fe but relaxes on annealing. • Reduction in strain dispersion in the MgO barrier by 40% above about 470 K. • No change in the in-plane “twist” mosaic throughout the annealing cycle.

Pengaruh Lama Miling Terhadap Sifat Absorpsi Material Penyimpan Hidrogen MgH2 yang Dikatalisasi Dengan Fe (The Role of Milling Time on the Absorption Behaviour of MgH2 Catalyzed by Fe

Directory of Open Access Journals (Sweden)

Mustanir Mustanir

2009-12-01

Full Text Available Hidrida logam berbasis MgH2 dengan sisipan 1 wt% katalis Fe telah berhasil disintesis dengan teknik ball milling. Hasil proses miling selama 80 jam menunjukkan bahwa ukuran butir material telah membentuk struktur nanokristal. Hal ini ditunjukkan oleh profil difraksi sinar-X dimana terjadi pelebaran puncakpuncak difraksinya dengan meningkatnya waktu miling. Hasil uji absorpsi secara gravimetrik diketahui bahwa MgH2 berkatalis 1 wt% Fe mampu menyerap hydrogen sebesar 5,5 wt% dalam waktu ~20 menit pada temperatur 300 oC. Hasil ini sekaligus memperlihatkan bahwa sejumlah kecil katalis Fe bekerja secara baik dalam memperbaiki sifat absorpsi material penyimpan hydrogen berbasis Mg.(Metal hydrides are of great interest as hydrogen storage media especially for automotive application. Hydrides of magnesium and magnesium alloys are particularly attractive as they combine potentially high hydrogen storage capacities, 7.6 wt%. But, unfortunately, the sorption properties are poor. For example, conventional hydrogenation of magnesium requires prolonged treatment at temperatures of 300 oC and above. Here, we report the absorption properties of MgH2 catalyzed with a small amount of Fe element (1wt% under argon atmosphere prepared by ball milling in 80 hours. As the results, it showed the influence of milling time on the absortion kinetics of material which could absorp hydrogen in amount 5.5 within 20 minutes at 300 oC. It is obvious that longer milling time and small amount of catalyst could improve the sorption properties of Mg-based hydrides. © 2009 BCREC UNDIP. All rights reserved[Received: 13rd November 2009, Revised: 25th December 2009, Accepted: 31st December 2009][How to Cite: M. Mustanir, Z. Jalil. (2009. Pengaruh Lama Miling Terhadap Sifat Absorpsi Material Penyimpan Hidrogen MgH2 yang Dikatalisasi Dengan Fe (The Role of Milling Time on the Absorption Behaviour of MgH2 Catalyzed by Fe. Bulletin of Chemical Reaction Engineering and Catalysis, 4(2: 69

Impact of interface manipulation of oxide on electrical transport properties and low-frequency noise in MgO/NiFe/MgO heterojunctions

International Nuclear Information System (INIS)

Li, Jian-wei; Zhao, Chong-jun; Feng, Chun; Yu, Guang-hua; Zhou, Zhongfu

2015-01-01

Low-frequency noise and magnetoresistance in sputtered-deposited Ta(5 nm)/MgO (3 nm)/NiFe(10 nm)/MgO(3 nm)/Ta(3 nm) films have been measured as a function of different annealing times at 400°C. These measurements did not change synchronously with annealing time. A significant increase in magnetoresistance is observed for short annealing times (of the order of minutes) and is correlated with a relatively small reduction in 1/f noise. In contrast, a significant reduction in 1/f noise is observed for long annealing times (of the order of hours) accompanied by a small change in magnetoresistance. After annealing for 2 hours, the 1/f noise decreases by three orders of magnitude. Transmission electron microscopy and slow positron annihilation results implicate the cause being micro-structural changes in the MgO layers and interfaces following different annealing times. The internal vacancies in the MgO layers gather into vacancy clusters to reduce the defect density after short annealing times, whereas the MgO/NiFe and the NiFe/MgO interfaces improve significantly after long annealing times with the amorphous MgO layers gradually crystallizing following the release of interfacial stress

Impact of interface manipulation of oxide on electrical transport properties and low-frequency noise in MgO/NiFe/MgO heterojunctions

Science.gov (United States)

Li, Jian-wei; Zhao, Chong-jun; Feng, Chun; Zhou, Zhongfu; Yu, Guang-hua

2015-08-01

Low-frequency noise and magnetoresistance in sputtered-deposited Ta(5 nm)/MgO (3 nm)/NiFe(10 nm)/MgO(3 nm)/Ta(3 nm) films have been measured as a function of different annealing times at 400°C. These measurements did not change synchronously with annealing time. A significant increase in magnetoresistance is observed for short annealing times (of the order of minutes) and is correlated with a relatively small reduction in 1/f noise. In contrast, a significant reduction in 1/f noise is observed for long annealing times (of the order of hours) accompanied by a small change in magnetoresistance. After annealing for 2 hours, the 1/f noise decreases by three orders of magnitude. Transmission electron microscopy and slow positron annihilation results implicate the cause being micro-structural changes in the MgO layers and interfaces following different annealing times. The internal vacancies in the MgO layers gather into vacancy clusters to reduce the defect density after short annealing times, whereas the MgO/NiFe and the NiFe/MgO interfaces improve significantly after long annealing times with the amorphous MgO layers gradually crystallizing following the release of interfacial stress.

Impact of interface manipulation of oxide on electrical transport properties and low-frequency noise in MgO/NiFe/MgO heterojunctions

Energy Technology Data Exchange (ETDEWEB)

Li, Jian-wei [School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhao, Chong-jun; Feng, Chun; Yu, Guang-hua [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhou, Zhongfu [School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China)

2015-08-15

Low-frequency noise and magnetoresistance in sputtered-deposited Ta(5 nm)/MgO (3 nm)/NiFe(10 nm)/MgO(3 nm)/Ta(3 nm) films have been measured as a function of different annealing times at 400°C. These measurements did not change synchronously with annealing time. A significant increase in magnetoresistance is observed for short annealing times (of the order of minutes) and is correlated with a relatively small reduction in 1/f noise. In contrast, a significant reduction in 1/f noise is observed for long annealing times (of the order of hours) accompanied by a small change in magnetoresistance. After annealing for 2 hours, the 1/f noise decreases by three orders of magnitude. Transmission electron microscopy and slow positron annihilation results implicate the cause being micro-structural changes in the MgO layers and interfaces following different annealing times. The internal vacancies in the MgO layers gather into vacancy clusters to reduce the defect density after short annealing times, whereas the MgO/NiFe and the NiFe/MgO interfaces improve significantly after long annealing times with the amorphous MgO layers gradually crystallizing following the release of interfacial stress.

Viscosity Measurements of SiO2-"FeO"-MgO System in Equilibrium with Metallic Fe

Science.gov (United States)

Chen, Mao; Raghunath, Sreekanth; Zhao, Baojun

2014-01-01

The present study delivers the measurements of viscosities in the SiO2-"FeO"-MgO system in equilibrium with metallic Fe. The rotational spindle technique was used for the measurements at the temperature range of 1523 K to 1773 K (1250 °C to 1500 °C). Molybdenum crucibles and spindles were employed in all measurements. The viscosity measurements were carried out at 31 to 47 mol pct SiO2 and up to 18.8 mol pct MgO. Analysis of the quenched sample by Electron probe X-ray microanalysis after the viscosity measurement enables the composition and microstructure of the slag to be directly linked with the viscosity. The replacement of "FeO" by MgO was found to increase viscosity and activation energy of the SiO2-"FeO"-MgO slags. The modified Quasi-chemical Viscosity Model was further optimized in this system based on the current viscosity measurements.

Phase boundary between cubic B1 and rhombohedral structures in (Mg,Fe)O magnesiowüstite determined by in situ X-ray diffraction measurements

Science.gov (United States)

Dymshits, Anna M.; Litasov, Konstantin D.; Shatskiy, Anton; Chanyshev, Artem D.; Podborodnikov, Ivan V.; Higo, Yuji

2018-01-01

The phase relations and equation of state of (Mg0.08Fe0.92)O magnesiowüstite (Mw92) have been studied using the Kawai-type high-pressure apparatus coupled with synchrotron radiation. To determine the phase boundary between the NaCl-type cubic (B1) and rhombohedral ( rB1) structures in Mw92, in situ X-ray observations were carried out at pressures of 0-35 GPa and temperatures of 300-1473 K. Au and MgO were used as the internal pressure markers and metallic Fe as oxygen fugacity buffer. The phase boundary between B1 and rB1 structures was described by a linear equation P (GPa) = 1.6 + 0.033 × T (K). The Clapeyron slope (d P/d T) determined in this study is close to that obtained at pressures above 70 GPa but steeper than that obtained for FeO. An addition of MgO to FeO structure expands the stability field of the rB1 phase to lower pressures and higher temperatures. Thus, the rB1 phase may be stabilized with respect to the B1 phase at a lower pressures. The pressure-volume-temperature equation of state of B1-Mw92 was determined up to 30 GPa and 1473 K. Fitting the hydrostatic compression data up to 30 GPa with the Birch-Murnaghan equation of state (EoS) yielded: unit cell volume ( V 0, T0), 79.23 ± 4 Å3; bulk modulus ( K 0, T0), 183 ± 4 GPa; its pressure derivative ( K' T ), 4.1 ± 0.4; (∂ K 0, T /∂ T) = -0.029 ± 0.005 GPa K‒1; a = 3.70 ± 0.27 × 10-5 K-1 and b = 0.47 ± 0.49 × 10-8 K-2, where α0, T = a + bT is the volumetric thermal expansion coefficient. The obtained bulk modulus of Mw92 is very close to the value expected for stoichiometric iron-rich (Mg,Fe)O. This result confirms the idea that the bulk modulus of (Mg,Fe)O is greatly affected by the actual defect structure, caused by either Mg2+ or vacancies.

Influence of chemical composition of CoFeB on tunneling magnetoresistance and microstructure in polycrystalline CoFeB/MgO/CoFeB magnetic tunnel junctions

International Nuclear Information System (INIS)

Tsunekawa, Koji; Choi, Young-Suk; Nagamine, Yoshinori; Djayaprawira, David D.; Takeuchi, Takashi; Kitamoto, Yoshitaka

2006-01-01

We report, for the first time, the correlation between tunneling magnetoresistance (TMR) and the microstructure of polycrystalline CoFeB/MgO/CoFeB magnetic tunnel junctions with various Co/Fe ratios in the (CoFe) 81 B 19 reference and free layers. It is found that the Co/Fe ratio in the (CoFe) 81 B 19 reference layer strongly affects the (001) out-of-plane texture of the MgO tunnel barrier, resulting in the variation in TMR ratio. Further microstructure characterization of the magnetic tunnel junction with a higher TMR ratio and a stronger (001) out-of-plane texture in the MgO tunnel barrier reveals a grain-to-grain lattice match between the crystallized bcc CoFeB reference layer and MgO with a 45deg rotational epitaxial relationship, that is, CoFeB(001)[110]//MgO(001)[100]. (author)

X-ray studies of interface Fe-oxide in annealed MgO based magnetic tunneling junctions

Energy Technology Data Exchange (ETDEWEB)

Telesca, D., E-mail: donaldtelesca@gmail.com [Department of Physics, University of Connecticut, 2152 Hillside Road, Storrs, CT 06269 (United States); Space Vehicles Directorate, Air Force Research Lab (AFRL), Kirtland AFB, NM 87117 (United States); Sinkovic, B. [Space Vehicles Directorate, Air Force Research Lab (AFRL), Kirtland AFB, NM 87117 (United States); Yang, See-Hun; Parkin, S.S.P. [IBM Amaden Research Center, 650 Harry Road, San Jose, CA 95120 (United States)

2012-08-15

Highlights: Black-Right-Pointing-Pointer This work concludes the presence of oxide in MgO/transition-metal bi-layers. Black-Right-Pointing-Pointer Thermal annealing causes a possible structural transformation of the oxide. Black-Right-Pointing-Pointer This is first evidence for a possible structural change of the oxide. Black-Right-Pointing-Pointer First use of the O K-edge XAS signature of TM oxides to confirm presence of oxide. Black-Right-Pointing-Pointer We see a diffusion of oxygen and a decrease in interface roughness. -- Abstract: X-ray absorption spectroscopy and X-ray scattering have been used to determine the oxidation reactions at the buried MgO/Fe interface as a result of the deposition of MgO. We confirm that Fe-oxide is present at the MgO/Fe and MgO/CoFe interfaces and amounts to less than 1 mL in thickness. The Fe-oxide is a mixture of different iron oxide phases within the ultra-thin layer which can be reduced following annealing. We observe the transformation of the interfacial oxide from a more Fe{sub 2}O{sub 3}-like phase to a more FeO-like phase following annealing, and that this process is most noticeable between the 200 and 350 Degree-Sign C annealing steps. In addition, the formation of a more bulk like MgO electronic structure following annealing was observed.

Photocatalytic degradation of methylene blue on magnetically separable MgFe2O4 under visible light irradiation

International Nuclear Information System (INIS)

Shahid, Muhammad; Jingling, Liu; Ali, Zahid; Shakir, Imran; Warsi, Muhammad Farooq; Parveen, Riffat; Nadeem, Muhammad

2013-01-01

A magnetically separable single-phase MgFe 2 O 4 photocatalyst with a spinel crystal structure was synthesized by using the solid-state reaction method. The formation of spinel structure is confirmed by X-ray diffraction and Fourier transform infrared spectroscopy. The magnetic measurements showed that the photocatalyst material can be separated from water when an external magnetic field is added and redispersed into water solution after the external magnetic field is eliminated. It is one of the promising photocatalysts for waste water treatment. The photocatalytic activity of MgFe 2 O 4 was investigated by using the photo-decomposition of methylene blue dye under visible light. The photoelectrochemical property of the MgFe 2 O 4 was studied by measuring their photocurrent–potential behavior in 1 M NaOH electrolyte under AM 1.5100 mW cm −2 illumination. - Graphical abstract: Highly efficient magnetically separable MgFe 2 O 4 photocatalyst for organic based impurities decomposition as well as for the production of H 2 gas was synthesized and characterized successfully (a) MgFe 2 O 4 photocatalyst in polluted water, (b) The photocatalyst (MgFe 2 O 4 ) is being attracted toward magnetic field for separation, (c) Hysteresis loop of MgFe 2 O 4 showing magnetic behavior. Highlights: ► New photocatalyst working in the visible range have been synthesized by facile cheap route. ► MgFe 2 O 4 photocatalyst showed well defined magnetically separable behavior. ► Excellent water splitting characteristics to produce H 2 was observed under visible light irradiation

Electronic structure of ferromagnet-insulator interfaces: Fe/MgO and Co/MgO

Energy Technology Data Exchange (ETDEWEB)

Mueller, M.

2007-07-11

In this thesis the electronic structure of Fe/MgO{sub x} and Co/MgO{sub x} ferromagnet-insulator interfaces, representing material systems which are widely used in magnetic tunnel junctions, is studied by means of spin- and angle-resolved photoemission spectroscopy. The photoemission studies focus particularly on the response of the ferromagnetic electronic system in contact with MgO of varying stoichiometries, as this reflects the mechanisms of metal-oxide bonding at real ferromagnet-insulator interfaces. The correlation between chemical bonding and electronic structure formation is analyzed by combining information from core- and valence-band photoemission spectroscopy. The spectral features are compared to band structure calculations, which are performed using the SPR-KKR method. The Fe/MgO and Co/MgO systems are prepared by molecular beam epitaxy under ultrahigh vacuum conditions on well-defined (4 x 6) GaAs(001) substrates. A structural analysis by means of low-energy electron diffraction (LEED) reveals their body-centered cubic crystalline structure, whereas the chemical characterization by Auger electron spectroscopy is used to quantify the chemical environment at the sample surfaces. The magnetic analysis, using the magneto-optical Kerr effect, reveals the uniaxial anisotropy of the ferromagnetic layers. A crucial parameter is given by the MgO degree of oxidation, which is addressed by means of core-level spectroscopy and quantified by suitable fitting procedures of the Mg 2p core level. The results of the photoemission experiments show, that the electronic structure of the Fe/MgO and Co/MgO ferromagnet/insulator interfaces and, consequently, the interfacial spin polarization are sensitively controlled by the interface chemistry. In particular, three distinct scenarios are identified: the nearly stoichiometric, the oxygen-deficient and the over-oxidized ferromagnet/MgO interface. Each case is defined by innate characteristics of the electronic structure at

Humic Acid and Water Management to Decrease Ferro (Fe2+ Solution and Increase Productivity of Established New Rice Field

Directory of Open Access Journals (Sweden)

Amrizal Saidi

2012-01-01

Full Text Available The purpose of this research was to gain a technological breakthrough in controlling Fe toxicity (Fe2+ on Ultisol ina new established rice field by using humic acid from rice straw compost and water management, so that optimalproduction of rice plants could be achieved. The experiment was designed using a 2 × 4 factorials with 3 replicationsin a split plot design. The main plot was water management consists of 2 levels: continuous and intermittentirrigation (2 weeks flooded and 2 weeks field capacity. Small plot was humic acid which was extracted from ricestraw compost by NaOH 0.5 N which consists of 4 levels: 0, 200, 400, and 600 mg kg-1. The results showed thatapplications of humic acid from 0 to 600 mg kg-1 that was followed by 2 weeks of intermittent irrigation decreasedFe2+ concentration. It was approaching levels that were not toxic to plants, with soil Fe2+ between 180-250 mg kg-1.The best treatment was found at the application of 600 mg kg-1 humic acid extracted from rice straw compostcombined with 2 week flooded – 2 weeks field capacity of water management. Those treatment decreased Fe2+concentration from 1,614 to 180 mg kg-1 and increased the dry weight of grain from 5.15 to 16.73 g pot-1 compared tocontinuous flooding and without humic acid application.

Mechanism of magnetoresistance ratio enhancement in MgO/NiFe/MgO heterostructure by rapid thermal annealing

Science.gov (United States)

Zhao, Chong-Jun; Liu, Yang; Zhang, Jing-Yan; Sun, Li; Ding, Lei; Zhang, Peng; Wang, Bao-Yi; Cao, Xing-Zhong; Yu, Guang-Hua

2012-08-01

To reveal thermal effects on the film quality/microstructure evolution and the resulted magnetoresistance (MR) ratio in MgO/NiFe/MgO heterostructures, positron annihilation spectroscopy studies have been performed. It is found that the ionic interstitials in the MgO layers recombine with the nearby vacancies at lower annealing temperatures (200-300 °C) and lead to a slow increase in sample MR. Meanwhile, vacancy defects agglomeration/removal and ordering acceleration in MgO will occur at higher annealing temperatures (450-550 °C) and the improved MgO and MgO/NiFe interfaces microstructure are responsible for the observed significant MR enhancement.

Mössbauer spectroscopy of ZnxMg1-x Fe2O4 (0 ≤ x ≤ 0.74) nanostructures crystallized from borate glasses

Science.gov (United States)

El Shabrawy, S.; Miglierini, M.; Schaaf, P.; Tzankov, D.; Georgieva, M.; Harizanova, R.; Rüssel, C.

2018-03-01

Glasses in the system 51.7 B2O3/9.3 K2O/1 P2O5/10.4 Fe2O3/(27.6 - y) MgO/y ZnO (with y = 0, 1, 2.5, 5, 7.5, 10, 13.8, and 20) were prepared by the conventional melt quenching method. The glass samples were thermally treated at 560 °C for 3 h in ambient conditions. Using 57Fe Mössbauer spectroscopy, the effect of the substitution of MgO by ZnO in the glass network and the effect on the precipitated crystallized phase was studied. The results showed that the ratio of Zn2+:Mg2+ in the precipitated crystals increases with the ZnO concentration in the glass. The isomer shift values indicated that iron occurs as Fe3+, which is distributed at the tetrahedral (A) and the octahedral [B] sites. Introducing ZnO leads to a relative increase of the Fe3+ concentration at the B sites at the expense of that occupying the A sites. This indicates the precipitation of ZnxMg1-x Fe2O4 nanoparticles, where Zn2+ ions favorably occupy the A sites. The average hyperfine field of the samples showed a strong dependence on the Zn concentration. At the highest Zn concentration of 13.8 and 20 mol%, the samples are paramagnetic, while for the smaller ones, the samples are superparamagnetic.

Influence of the surface topography, morphology and structure on magnetic properties of ion beam sputtered iron layers, Fe/Cr/Fe- and Fe/MgO/Fe multilayers; Untersuchung der Morphologie und magnetische Eigenschaften von ionenstrahl-gesputterten Eisen-Einzelschichten, Fe/Cr/Fe- und Fe/MgO/Fe-Schichtsystemen

Energy Technology Data Exchange (ETDEWEB)

Steeb, Alexandra

2007-04-05

In this PhD Thesis, the influence of the surface topography, morphology and structure on magnetic properties of ion beam sputtered iron layers on GaAs is examined. To analyze the structure of the produced iron films, low energy electron diffraction and scanning tunneling microscopy is employed. The utilized methods to investigate the magnetic properties are Kerr- and SQUID-magnetometry and ferromagnetic resonance. It is demonstrated that on untreated as well as on presputtered and heated GaAs substrates the sputtered iron films grow epitaxially. The least surface roughness of 1 A exhibit iron films grown on untreated GaAs, while iron films on heated GaAs have the highest roughness of 30 A. The largest crystal anisotropy constant is found for the presputtered GaAs/Fe-System. For this preparation method, two monolayers of iron are determined to be magnetically dead layers. At a film thickness of 100 A, 83% of the value for saturation magnetization of bulk iron are achieved. The small observed FMR-linewidths confirm the good bulk properties of the ion beam sputtered iron. Furthermore, an antiferromagnetic interlayer exchange coupling in sputtered Fe/Cr/Fe-films was achieved. For a thickness of 12 to 17 A of the chrome interlayer, a coupling strength up to 0.2 mJ/m{sup 2} is found. To account for the small coupling strength, a strong intermixing at the interface is assumed. Finally, epitaxial Fe/MgO/Fe/FeMn multilayers are deposited on GaAs. After the structuring, it is possible to detect tunneling processes in the tunneling contacts with current-voltage measurements. The tunnel magneto resistance values of 2% are small, which can be explained by the absence of sharp, well-defined interfaces between the Fe/FeMn and the Fe/MgO interfaces. These results demonstrate, that analog to MBE the ion beam sputtering method realizes good magnetic bulk properties. However, interface sensitive phenomena are weakened because of a strong intermixing at the interfaces. (orig.)

Adsorption of As(V) from water using Mg-Fe-based hydrotalcite (FeHT)

Energy Technology Data Exchange (ETDEWEB)

Tuerk, T. [Mineral Processing Division, Department of Mining Engineering, Karadeniz Technical University, 61080 Trabzon (Turkey); Alp, I., E-mail: ialp@ktu.edu.tr [Mineral Processing Division, Department of Mining Engineering, Karadeniz Technical University, 61080 Trabzon (Turkey); Deveci, H. [Mineral Processing Division, Department of Mining Engineering, Karadeniz Technical University, 61080 Trabzon (Turkey)

2009-11-15

This paper describes a study of the sorptive removal of arsenate (As(V)) from aqueous solutions by synthetically prepared Mg-Fe-based hydrotalcites (FeHT) as layered double hydroxide (LDH) adsorbents. The synthesis of Fe{sup 3+}-substituted hydrotalcites (FeHT) with the chemical formula [Mg(II){sub 6}Fe(III){sub 2}(OH){sub 16}]{sup 2+}[CO{sub 3} x yH{sub 2}O]{sup 2-} was achieved by a co-precipitation method. The reaction products were characterized by powder X-ray diffraction analysis. The influences of solution pH, initial arsenate (As(V)) concentration, and sorbent concentration were investigated in multiple kinetic runs. The adsorption rates and isotherms were investigated in batch experiments. The pseudo-first-order and second-order kinetic models were tested and the latter was found to fit better to the experimental data. Langmuir and Freundlich isotherms were used to describe the adsorption data from equilibrium experiments. The results have shown that FeHT has a high arsenate removal efficiency, with the ability to reduce the concentration of arsenate in the aqueous solution from an initial value of 330 {mu}g/l to <10 {mu}g/l (i.e. below the limit value specified by WHO).

Moment mapping of body-centered-cubic Fe{sub x}Mn{sub 1−x} alloy films on MgO(001)

Energy Technology Data Exchange (ETDEWEB)

Idzerda, Y. U., E-mail: idzerda@physics.montana.edu; Bhatkar, H. [Department of Physics, Montana State University, Bozeman, Montana 59717 (United States); Arenholz, E. [Advanced Light Source, Lawrence Berkeley National Laboratories, Berkeley, California 59717 (United States)

2015-05-07

The alloy composition and elemental magnetic moments of bcc single crystal films of compositionally graded Fe{sub x}Mn{sub 1−x} films (20 nm thick films with 0.8 ≤ x ≤ 0.9) grown on MgO(001) are spatially mapped using X-ray absorption spectroscopy and magnetic circular dichroism. Electron diffraction measurements on single composition samples confirmed that the structure of Fe{sub x}Mn{sub 1−x} films remained epitaxial and in the bcc phase from 0.65 ≤ x ≤ 1, but rotated 45° with respect to the MgO(001) surface net. This is beyond the bulk bcc stability limit of x = 0.88. The Fe moment is found to gradually reduce with increasing Mn content with a very abrupt decline at x = 0.85, a slightly higher composition than observed in the bulk. Surprisingly, the Mn exhibits a very small net moment (<0.1 μ{sub B}) at all compositions, suggesting a complex Mn spin structure.

First-principles investigation of the effect of oxidation on the electronic structure and magnetic properties at the FeRh/MgO (0 0 1) interface

Energy Technology Data Exchange (ETDEWEB)

Sakhraoui, T., E-mail: tsakhrawi@yahoo.com [Laboratoire de la Matière Condensée et des Nanosciences, Département de Physique, Faculté des Sciences de Monastir, 5019 Monastir (Tunisia); Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg (France); Said, M. [Laboratoire de la Matière Condensée et des Nanosciences, Département de Physique, Faculté des Sciences de Monastir, 5019 Monastir (Tunisia); Alouani, M. [Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg (France)

2017-06-15

Highlights: • Density functional theory is used to study the interface between the FeRh alloy and MgO. • We focus on the effect of the oxidation on the electronic structure and magnetic properties of the FeRh/MgO (0 0 1) interface. • We show the change on the structure of the Fe-d states. • We examine the charge transfer and the local spin density modification after interface oxidation. - Abstract: The effect of interfacial oxidation on electronic structure and magnetic properties at the FeRh/MgO (0 0 1) interface is studied by ab initio methods. The results show the formation of an interfacial FeO-like layer between the FeRh and the MgO barrier, which has a direct impact on Fe e{sub g} states at the interface. It is shown that these e{sub g} states are more affected than that the t{sub 2g} states at the Fermi level due to the strong hybridization of these states with the p-states of oxygen. Thus, the oxidation modifies crucially the electronic structure and the magnetic properties as compared to those of an ideal interface. In particular, it was found that spin polarization of the ferromagnetic state is substantially enhanced. A simple two-current Julliere model shows that the TMR increases with oxidation.

Transport properties and exponential n-values of Fe/MgB2 tapes with various MgB2 particle sizes

International Nuclear Information System (INIS)

Lezza, P.; Abaecherli, V.; Clayton, N.; Senatore, C.; Uglietti, D.; Suo, H.L.; Fluekiger, R.

2004-01-01

Fe/MgB 2 tapes have been prepared starting with pre-reacted binary MgB 2 powders. As shown by resistive and inductive measurements, the reduction of particle size to a few microns by ball milling has little influence on B c2 , while the superconducting properties of the individual MgB 2 grains are essentially unchanged. Reducing the particle size causes an enhancement of B irr from 14 to 16 T, while J c has considerably increased at high fields, its slope J c (B) being reduced. At 4.2 K, values of 5.3 x 10 4 and 1.2 x 10 3 A/cm 2 were measured at 3.5 and 10 T, respectively, suggesting a dominant role of the conditions at the grain interfaces. A systematic variation of these conditions at the interfaces is undertaken in order to determine the limit of transport properties for Fe/MgB 2 tapes. The addition of 5% Mg to MgB 2 powder was found to affect neither J c nor B c2 . For the tapes with the highest J c values, very high exponential n factors were measured: n=148, 89 and 17 at 3.5, 5 and 10 T, respectively and measurements of critical current versus applied strain have been performed. The mechanism leading to high transport critical current densities of filamentary Fe/MgB 2 tapes based on MgB 2 particles is discussed

Determination of micro mineral Fe on cow meat and liver

International Nuclear Information System (INIS)

Natalia Adventini; Muhayatun; Syukria Kurniawati; Endang; Yuni Setyowat

2010-01-01

Fe deficiency is common in development countries. Fe deficiency could decreased the IQ level, immune function and work performance, impacts decreasing human resource quality. Beef and liver are Fe source which more easily absorbed compare to Fe found in plant products. Therefore, the Fe determination in beef and liver need to be carried out using INAA. Instrumental neutron activation analysis is a method for qualitative and quantitative determination of elements based on the measurement of characteristic radiation from radionuclide formed by neutron irradiation of the material. The Sixteen beef and liver from feed treatment cows were collected. Method validation using RM IAEAA-13 gave accuracy and precise were 99 % and 3,3 % respectively. Fe concentration in 16 beef and liver were obtained between 5.5-18.6 mg/kg wet weight with average value was 12.2±4.0 mg/kg and 22.9-4.7 mg/kg with average value was 35.2±8.7 mg/kg. Generally, this value gave the same result from other countries. Fe determination in beef and liver is not only expected to be a scientific based reference but also to update Indonesia food stuff composition data. (author)

Formation of Fe/mg Smectite Under Acidic Conditions from Synthetic Adirondack Basaltic Glass: an Analog to Fe/mg Smectite Formation on Mars

Science.gov (United States)

Sutter, B.; Peretyazhko, T.; Morris, R. V.; Ming, D. W.

2014-01-01

Smectite has been detected as layered material hundreds of meters thick, in intracrater depositional fans, in plains sediments, and deposits at depth on Mars. If early Mars hosted a dense CO2 atmosphere, then extensive carbonate should have formed in the neutral/alkaline conditions expected for smectite formation. However, large carbonate deposits on Mars have not been discovered. Instead of neutral to moderately alkaline conditions, early Mars may have experienced mildly acidic conditions that allowed for Fe/Mg smectite formation but prevented widespread carbonate formation. The objective of this work is to demonstrate that Fe(II)/Mg saponite and nontronite can form in mildly acidic solutions (e.g., pH 4). Synthetic basaltic glass (Smectite was confirmed as the phyllosilicate after treatments with glycerol and KCl and heating to 550 C. Trioctahedral saponite was confirmed by the presence of a 4.58 to 4.63 Angstroms (02l) and 1.54Angstroms (060) peaks. Saponite concentration was highest, as indicated by XRD peak intensity, in the 10 mM Mg treatment followed by the 0 mM and then 10 mM Fe(II) treatments. This order of sapontite concentration suggests that Fe(II) additions may have a role in slowing the kinetics of saponite formation relative to the other treatments. Nontronite synthesis was attempted by exposing Adirondack basaltic glass to pH 4 oxic solutions (without N2 purge) at 200 C for 14 days. X-ray diffraction analysis indicated that mixtures of trioctahedral (saponite) and dioctahedral (nontronite) may have formed in these experiments based on the 02l and 060 peaks. Moessbauer analysis coupled with future experiments are planned to verify if nontronite can be formed under mildly acidic and oxic conditions. Results of this work demonstrate that acidic conditions could have occurred on an early Mars, which allowed for smectite formation but inhibited carbonate formation.

The Influence of CuFe2O4 Nanoparticles on Superconductivity of MgB2

Science.gov (United States)

Novosel, Nikolina; Pajić, Damir; Skoko, Željko; Mustapić, Mislav; Babić, Emil; Zadro, Krešo; Horvat, Joseph

The influence of CuFe2O4 nanoparticle doping on superconducting properties of Fe-sheated MgB2 wires has been studied. The wires containing 0, 3 and 7.5 wt.% of monodisperse superparamagnetic nanoparticles (˜7 nm) were sintered at 650°C or 750°C for 1 hour in the pure argon atmosphere. X-ray diffraction patterns of doped samples showed very small maxima corresponding to iron boride and an increase in the fraction of MgO phase indicating some interaction of nanoparticles with Mg and B. Both magnetic and transport measurements (performed in the temperature range 2-42 K and magnetic field up to 16 T) showed strong deterioration of the superconducting properties upon doping with CuFe2O4. The transition temperatures, Tc, of doped samples decreased for about 1.4 K per wt.% of CuFe2O4. Also, the irreversibility fields Birr(T) decreased progressively with increasing doping. Accordingly, also the suppression of Jc with magnetic field became stronger. The observed strong deterioration of superconducting properties of MgB2 wires is at variance with reported enhancement of critical currents at higher temperatures (determined from magnetization) in bulk MgB2 samples doped with Fe3O4 nanoparticles. The probable reason for this discrepancy is briefly discussed

Tunneling magnetoresistance in Fe{sub 3}Si/MgO/Fe{sub 3}Si(001) magnetic tunnel junctions

Energy Technology Data Exchange (ETDEWEB)

Tao, L. L.; Liang, S. H.; Liu, D. P.; Wei, H. X.; Han, X. F., E-mail: xfhan@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Wang, Jian [Department of Physics and the Center of Theoretical and Computational Physics, The University of Hong Kong, Hong Kong (China)

2014-04-28

We present a theoretical study of the tunneling magnetoresistance (TMR) and spin-polarized transport in Fe{sub 3}Si/MgO/Fe{sub 3}Si(001) magnetic tunnel junction (MTJ). It is found that the spin-polarized conductance and bias-dependent TMR ratios are rather sensitive to the structure of Fe{sub 3}Si electrode. From the symmetry analysis of the band structures, we found that there is no spin-polarized Δ{sub 1} symmetry bands crossing the Fermi level for the cubic Fe{sub 3}Si. In contrast, the tetragonal Fe{sub 3}Si driven by in-plane strain reveals half-metal nature in terms of Δ{sub 1} state. The giant TMR ratios are predicted for both MTJs with cubic and tetragonal Fe{sub 3}Si electrodes under zero bias. However, the giant TMR ratio resulting from interface resonant transmission for the former decreases rapidly with the bias. For the latter, the giant TMR ratio can maintain up to larger bias due to coherent transmission through the majority-spin Δ{sub 1} channel.

Effect of TiON–MgO intermediate layer on microstructure and magnetic properties of L1{sub 0} FePt–C–SiO{sub 2} films

Energy Technology Data Exchange (ETDEWEB)

Deng, J.Y. [Department of Materials Science and Engineering, National University of Singapore, Singapore 117576 (Singapore); Dong, K.F. [School of Automation, China University of Geosciences, Wuhan 430074 (China); Peng, Y.G.; Ju, G.P. [Seagate Technology, Fremont, CA 94538 (United States); Hu, J.F. [Data Storage Institute (DSI), Singapore 117608 (Singapore); Chow, G.M.; Chen, J.S. [Department of Materials Science and Engineering, National University of Singapore, Singapore 117576 (Singapore)

2016-11-01

The microstructure and magnetic properties of L1{sub 0} FePt–C–SiO{sub 2} films grown on TiON–MgO intermediate layer were studied. TiON–MgO layer was deposited by co-sputtering TiN and MgO–TiO{sub 2} targets at 380 °C. With increasing MgO–TiO{sub 2} doping concentration, the contact angle between FePt grains with intermediate layer gradually increased, and it was close to 90° when the volume percentage of MgO–TiO{sub 2} reached 30%. At this condition, a high out-of-plane coercivity of 19.1 kOe was obtained, while the opening-up of in-plane M-H loop was very narrow. Moreover, it was found that the out-of-plane coercivity can be further improved to 21.6 kOe, by slightly increasing the percentage of MgO–TiO{sub 2} to 35 vol%. - Highlights: • The effect of TiON–MgO intermediate layer was studied. • With increasing the MgO composition, the surface energy of intermediate layer increased, and the FePt/TiON–MgO interfacial energy decreased. The contact angle of FePt grains with intermediate layer increased with the MgO composition, and 90° contact angle could be achieved by optimizing the MgO composition. • Good perpendicular magnetic anisotropy was retained with large out-of-plane coercivity and narrow in-plane opening-up.

Sequential magnetic switching in Fe/MgO(001) superlattices

Science.gov (United States)

Magnus, F.; Warnatz, T.; Palsson, G. K.; Devishvili, A.; Ukleev, V.; Palisaitis, J.; Persson, P. O. Å.; Hjörvarsson, B.

2018-05-01

Polarized neutron reflectometry is used to determine the sequence of magnetic switching in interlayer exchange coupled Fe/MgO(001) superlattices in an applied magnetic field. For 19.6 Å thick MgO layers we obtain a 90∘ periodic magnetic alignment between adjacent Fe layers at remanence. In an increasing applied field the top layer switches first followed by its second-nearest neighbor. For 16.4 Å MgO layers, a 180∘ periodic alignment is obtained at remanence and with increasing applied field the layer switching starts from the two outermost layers and proceeds inwards. This sequential tuneable switching opens up the possibility of designing three-dimensional magnetic structures with a predefined discrete switching sequence.

Double-layered perpendicular magnetic recording media of granular-type FePt-MgO films

International Nuclear Information System (INIS)

Zhang Zhengang; Singh, Amarendra K.; Yin Jinhua; Perumal, A.; Suzuki, Takao

2005-01-01

The recording performance of double-layered granular-type FePt-MgO perpendicular magnetic recording media fabricated onto glass discs by sputtering is investigated. The (0 0 1)-textured FePt granular films are obtained by annealing FePt/MgO multilayers. Three different multilayer structures are compared in their magnetic properties and recording SNR performances. To evaluate thermal stability property of these granular-type FePt disks, the time-dependent magnetic force microscope (MFM) signal from the written bits on one of these disks is recorded in the temperature range 25-200 degree sign C. The signal decay at high observation temperature is interpreted based on the temperature dependence of magnetic anisotropy (K u )

Investigation of iron spin crossover pressure in Fe-bearing MgO using hybrid functional

Science.gov (United States)

Cheng, Ya; Wang, Xianlong; Zhang, Jie; Yang, Kaishuai; Zhang, Chuanguo; Zeng, Zhi; Lin, Haiqin

2018-04-01

Pressure-induced spin crossover behaviors of Fe-bearing MgO were widely investigated by using an LDA  +  U functional for describing the strongly correlated Fe–O bonding. Moreover, the simulated spin crossover pressures depend on the applied U values, which are sensitive to environments and parameters. In this work, the spin crossover pressures of (Mg1‑x ,Fe x )O are investigated by using the hybrid functional with a uniform parameter. Our results indicate that the spin crossover pressures increase with increasing iron concentration. For example, the spin crossover pressure of (Mg0.03125,Fe0.96875)O and FeO was 56 GPa and 127 GPa, respectively. The calculated crossover pressures agreed well with the experimental observations. Therefore, the hybrid functional should be an effective method for describing the pressure-induced spin crossover behaviors in transition metal oxides.

Moessbauer study of Mg-Ni(Fe) alloys processed as materials for solid state hydrogen storage

Energy Technology Data Exchange (ETDEWEB)

Palade, P.; Principi, G., E-mail: giovanni.principi@unipd.it; Sartori, S.; Maddalena, A. [Universita di Padova, Settore Materiali, DIM (Italy); Lo Russo, S. [Universita di Padova, Dipartimento di Fisica (Italy); Schinteie, G.; Kuncser, V.; Filoti, G. [National Institute for Materials Physics, Solid State Magnetism Department (Romania)

2006-02-15

Mg-Ni-Fe magnesium-rich intermetallic compounds were prepared following two distinct routes. A Mg{sub 88}Ni{sub 11}Fe{sub 1} sample (A) was prepared by melt spinning Mg-Ni-Fe pellets and then by high-energy ball milling for 6 h the obtained ribbons. A (MgH{sub 2}){sub 88}Ni{sub 11}Fe{sub 1} sample (B) was obtained by high-energy ball milling for 20 h a mixture of Ni, Fe and MgH{sub 2} powders in the due proportions. A SPEX8000 shaker mill with a 10:1 ball to powder ratio was used for milling in argon atmosphere. The samples were submitted to repeated hydrogen absorption/desorption cycles in a Sievert type gas-solid reaction controller at temperatures in the range 520 - 590 K and a maximum pressure of 2.5 MPa during absorption. The samples were analysed before and after the hydrogen absorption/desorption cycles by X-ray diffraction and Moessbauer spectroscopy. The results concerning the hydrogen storage properties of the studied compounds are discussed in connection with the micro-structural characteristics found by means of the used analytical techniques. The improved kinetics of hydrogen desorption for sample A, in comparison to sample B, has been ascribed to the different behaviour of iron atoms in the two cases, as proved by Moessbauer spectroscopy. In fact, iron results homogeneously distributed in sample A, partly at the Mg{sub 2}Ni grain boundaries, with catalytic effect on the gas-solid reaction; in sample B, instead, iron is dispersed inside the hydride powder as metallic iron or superparamagnetic iron.

Synthesis and adsorption properties of hierarchical Fe{sub 3}O{sub 4}@MgAl-LDH magnetic microspheres

Energy Technology Data Exchange (ETDEWEB)

Wu, Xiaoge; Li, Bo; Wen, Xiaogang, E-mail: wenxg@scu.edu.cn [Sichuan University, School of Materials Science and Engineering (China)

2017-04-15

In this study, Fe{sub 3}O{sub 4} microspheres were prepared by a hydrothermal method, and then the synthesized Fe{sub 3}O{sub 4} microspheres were used as template to prepare Fe{sub 3}O{sub 4}@MgAl-LDH composite microspheres by a coprecipitation process. Morphology, composition, and crystal structure of synthesized nanomaterials were characterized by X-ray powder diffractometry, scanning electron microscopy, and Fourier transform infrared spectroscopy technologies. The composite hierarchical microspheres are composed of inner Fe{sub 3}O{sub 4} core and outer MgAl-LDH-nanoflake layer, and the average thickness of MgAl-LDH-nanoflake is about 70 nm. The adsorption property of the products toward congo red was also measured using UV–vis spectrometer. The result demonstrated that the Fe{sub 3}O{sub 4}@MgAl-LDH composite adsorbent could remove 99.8% congo red in 30 min, and the maximum adsorption capacity is about 404.6 mg/g, while congo red removal rate of pure MgAl-LDH and Fe{sub 3}O{sub 4} are only 86.3 and 53.1% in 40 min, respectively, and their adsorption capacity are 345.72 and 220.56 mg/g, respectively. It indicates the composite Fe{sub 3}O{sub 4}@ MgAl-LDH nanomaterials have better adsorption performance than pure Fe{sub 3}O{sub 4} and MgAl-LDH nanomaterials. In addition, the magnetic nanocomposites could be separated easily, and it demonstrated good cycle performance.

Modeling Fe II Emission and Revised Fe II (UV) Empirical Templates for the Seyfert 1 Galaxy I Zw 1

Science.gov (United States)

Bruhweiler, F.; Verner, E.

2008-03-01

We use the narrow-lined broad-line region (BLR) of the Seyfert 1 galaxy, I Zw 1, as a laboratory for modeling the ultraviolet (UV) Fe II 2100-3050 Å emission complex. We calculate a grid of Fe II emission spectra representative of BLR clouds and compare them with the observed I Zw 1 spectrum. Our predicted spectrum for log [nH/(cm -3) ] = 11.0, log [ΦH/(cm -2 s-1) ] = 20.5, and ξ/(1 km s-1) = 20, using Cloudy and an 830 level model atom for Fe II with energies up to 14.06 eV, gives a better fit to the UV Fe II emission than models with fewer levels. Our analysis indicates (1) the observed UV Fe II emission must be corrected for an underlying Fe II pseudocontinuum; (2) Fe II emission peaks can be misidentified as that of other ions in active galactic nuclei (AGNs) with narrow-lined BLRs possibly affecting deduced physical parameters; (3) the shape of 4200-4700 Å Fe II emission in I Zw 1 and other AGNs is a relative indicator of narrow-line region (NLR) and BLR Fe II emission; (4) predicted ratios of Lyα, C III], and Fe II emission relative to Mg II λ2800 agree with extinction corrected observed I Zw 1 fluxes, except for C IV λ1549 (5) the sensitivity of Fe II emission strength to microturbulence ξ casts doubt on existing relative Fe/Mg abundances derived from Fe II (UV)/Mg II flux ratios. Our calculated Fe II emission spectra, suitable for BLRs in AGNs, are available at http://iacs.cua.edu/people/verner/FeII. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 05-26555.

Temperature dependence of the interfacial magnetic anisotropy in W/CoFeB/MgO

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Kyoung-Min Lee

2017-06-01

Full Text Available The interfacial perpendicular magnetic anisotropy in W/CoFeB (1.2 ∼ 3 nm/MgO thin film structures is strongly dependent on temperature, and is significantly reduced at high temperature. The interfacial magnetic anisotropy is generally proportional to the third power of magnetization, but an additional factor due to thermal expansion is required to explain the temperature dependence of the magnetic anisotropy of ultrathin CoFeB films. The reduction of the magnetic anisotropy is more prominent for the thinner films; as the temperature increases from 300 K to 400 K, the anisotropy is reduced ∼50% for the 1.2-nm-thick CoFeB, whereas the anisotropy is reduced ∼30% for the 1.7-nm-thick CoFeB. Such a substantial reduction of magnetic anisotropy at high temperature is problematic for data retention when incorporating W/CoFeB/MgO thin film structures into magneto-resistive random access memory devices. Alternative magnetic materials and structures are required to maintain large magnetic anisotropy at elevated temperatures.

Growth, structure and magnetic properties of FePt nanostructures on NaCl(001) and MgO(001)

International Nuclear Information System (INIS)

Liscio, F; Maret, M; Doisneau-Cottignies, B; Makarov, D; Albrecht, M; Roussel, H

2010-01-01

A comparison of the structural and magnetic properties of FePt nanostructures grown at different temperatures on NaCl(001) and MgO(001) substrates is presented. A strong influence of the deposition temperature on the epitaxial growth as well as on the size distribution of FePt nanostructures grown on NaCl substrates is observed. In spite of a large lattice mismatch between FePt and NaCl, a 'cube-over-cube' growth of nanostructures with a narrow size distribution was achieved at 520 K. Moreover, the growth of FePt nanostructures on NaCl(001) is not preceded by the formation of a wetting layer as observed on MgO(001). The higher degree of L1 0 chemical ordering in FePt nanostructures grown on MgO(001) accompanied by the absence of L1 0 variants with an in-plane tetragonal c-axis indicates that the tensile epitaxial stress induced by the MgO substrate is a key factor in the formation of the L1 0 phase with an out-of-plane c-axis. Superparamagnetic behavior is revealed for the FePt nanostructures grown on NaCl(001) due to their small size and relatively poor chemical order.

The Formation of Fe/Mg Smectite Under Mildly Acidic Conditions on Early Mars

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Sutter, B.; Golden, D. C.; Ming, Douglas W.; Niles, P. B.

2011-01-01

The detection of Fe/Mg smectites and carbonate in Noachian and early Hesperian terrain of Mars suggests that neutral to mildly alkaline conditions prevailed during the early history of Mars. If early Mars surface geochemical conditions were neutral to moderately alkaline with a denser CO2 atmosphere than today, then large carbonates deposits should be more widely detected in Noachian terrain. Why have so few carbonate deposits been detected compared to Fe/Mg smectites? Fe/Mg smectites on early Mars formed under mildly acidic conditions, which would preclude the extensive formation of carbonate deposits. The goal of the proposed work is to evaluate the formation of Fe/Mg smectites under mildly acidic conditions.

Intravenous rocuronium 0.3 mg/kg improves the conditions for tracheal intubation in cats: a randomized, placebo-controlled trial.

Science.gov (United States)

Sakai, Daniel M; Zornow, Kailee Anne; Campoy, Luis; Cable, Christina; Appel, Leslie D; Putnam, Holly J; Martin-Flores, Manuel

2018-01-01

Objectives We evaluated the use of rocuronium 0.3 mg/kg intravenously (IV) to facilitate tracheal intubation in cats anesthetized for elective ovariohysterectomy. Methods Thirty female cats were randomly allocated to receive rocuronium 0.3 mg/kg IV or an equal volume of normal saline, following induction of anesthesia with ketamine and midazolam. Thirty seconds after induction, a single investigator, unaware of treatment allocation, attempted tracheal intubation. The number of attempts and the time to complete intubation were measured. Intubating conditions were assessed as acceptable or unacceptable based on a composite score consisting of five different components. Duration of apnea after induction was measured and cases of hemoglobin desaturation (SpO 2 rocuronium 12 s [range 8-75 s]; saline 60 s [range 9-120 s]) and with fewer attempts (rocuronium 1 [range 1-2]; saline 2 [range 1-3], both P = 0.006) in cats receiving rocuronium. Unacceptable intubating conditions on the first attempt occurred in 3/15 cats with rocuronium and in 10/15 with saline ( P = 0.01). Apnea lasted 4 ± 1.6 mins with rocuronium and 2.3 ± 0.5 mins with saline ( P = 0.0007). No cases of desaturation were observed. Conclusions and relevance Rocuronium 0.3 mg/kg IV improves intubating conditions compared with saline and reduces the time and number of attempts to intubate with only a short period of apnea in cats.

Dehydriding Process and Hydrogen–Deuterium Exchange of LiBH4–Mg2FeD6 Composites

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Guanqiao Li

2015-06-01

Full Text Available The dehydriding process and hydrogen–deuterium exchange (H–D exchange of xLiBH4 + (1 − xMg2FeD6 (x = 0.25, 0.75 composites has been studied in detail. For the composition with x = 0.25, only one overlapping mass peak of all hydrogen and deuterium related species was observed in mass spectrometry. This implied the simultaneous dehydriding of LiBH4 and Mg2FeD6, despite an almost 190 °C difference in the dehydriding temperatures of the respective discrete complex hydrides. In situ infrared spectroscopy measurements indicated that H–D exchange between [BH4]− and [FeD6]4− had occurred during ball-milling and was promoted upon heating. The extent of H–D exchange was estimated from the areas of the relevant mass signals: immediately prior to the dehydriding, more than two H atoms in [BH4]− was replaced by D atoms. For x = 0.75, H–D exchange also occurred and about one to two H atoms in [BH4]− was replaced by D atoms immediately before the dehydriding. In contrast to the situation for x = 0.25, firstly LiBH4 and Mg2FeD6 dehydrided simultaneously with a special molar ratio = 1:1 at x = 0.75, and then the remaining LiBH4 reacted with the Mg and Fe derived from the dehydriding of Mg2FeD6.

The Systematics of Activity-Composition Relations in Mg-Fe2+ Oxide and Silicate Solid Solutions

Science.gov (United States)

O'Neill, H. S.

2006-12-01

The need to quantify activity-composition relations of mineral solid solutions for petrologic modelling has prompted many experimental studies, but different studies on the same system often appear to show a startling lack of consistency. A good example is Mg-Fe2+ mixing in garnet (the pyrope-almandine join). This is understandable because the energies of mixing in solid solutions are often obtained experimentally as small difference between large numbers. In particular, the fallacy of using a sequential approach to data fitting to a thermodynamic model leads to the accumulated errors being artificially concentrated onto the last step of the fitting process, which is usually that part of the model dealing with the excess energies of mixing. This gives rise to erroneous activity-composition relations, often apparently showing complex deviations from ideality. Systemizing the results of many studies can reveal underlying patterns of behaviour while also identifying outliers and anomalies that may be worth reinvestigating. Davies and Navrotsky [1] showed that the energies of mixing of many different pairs of ions with the same charge correlated well with the difference in molar volumes of the end-members, within a particular crystal structure. This empirical work is now supported by theoretical calculations. It underlies the modern approach to melt/crystal trace-element partitioning. Provided an internally consistent dataset is used, an analogous correlation may be demonstrated across different crystal structures for the mixing of one pair of ions, such as Mg and Fe2+. Activity-composition relations in MgO-"FeO" magnesiowuestite solutions in equilibrium with iron metal were used to obtain the properties of Mg-Fe olivine solutions from magnesiowuestite/olivine partitioning [2]. New results at 1400 K, 1 bar and 1473 K, 25 kb (O'Neill and Pownceby, in prep.) confirm previous work that mixing in Mg-Fe olivine is regular (symmetrical) with W Mg-Fe = 2.5 kJ/mol, with an

Hydrogen storage of Mg1−xMxH2 (M = Ti, V, Fe) studied using first-principles calculations

International Nuclear Information System (INIS)

Bhihi, M.; Lakhal, M.; Benyoussef, A.; El Kenz, A.; Labrim, H.; Mounkachi, O.; Hlil, E.K.

2012-01-01

In this work, the hydrogen storage properties of the Mg-based hydrides, i.e., Mg 1−x M x H 2 (M = Ti, V, Fe, 0 ≤ x ≤ 0.1), are studied using the Korringa—Kohn—Rostoker (KKR) calculation with the coherent potential approximation (CPA). In particular, the nature and concentrations of the alloying elements and their effects are studied. Moreover, the material's stability and hydrogen storage thermodynamic properties are discussed. In particular, we find that the stability and the temperature of desorption decrease without significantly affecting the storage capacities

Mg doped Li2FeSiO4/C nanocomposites synthesized by the solvothermal method for lithium ion batteries.

Science.gov (United States)

Kumar, Ajay; Jayakumar, O D; Jagannath; Bashiri, Parisa; Nazri, G A; Naik, Vaman M; Naik, Ratna

2017-10-14

A series of porous Li 2 Fe 1-x Mg x SiO 4 /C (x = 0, 0.01, 0.02, 0.04) nanocomposites (LFS/C, 1Mg-LFS/C, 2Mg-LFS and 4Mg-LFS/C) have been synthesized via a solvo-thermal method using the Pluronic P123 polymer as an in situ carbon source. Rietveld refinement of the X-ray diffraction data of Li 2 Fe 1-x Mg x SiO 4 /C composites confirms the formation of the monoclinic P2 1 structure of Li 2 FeSiO 4 . The addition of Mg facilitates the growth of impurity-free Li 2 FeSiO 4 with increased crystallinity and particle size. Despite having the same percentage of carbon content (∼15 wt%) in all the samples, the 1Mg-LFS/C nanocomposite delivered the highest initial discharge capacity of 278 mA h g -1 (∼84% of the theoretical capacity) at the C/30 rate and also exhibited the best rate capability and cycle stability (94% retention after 100 charge-discharge cycles at 1C). This is attributed to its large surface area with a narrow pore size distribution and a lower charge transfer resistance with enhanced Li-ion diffusion coefficient compared to other nanocomposites.

Feasibility of diffuse reflectance infrared Fourier spectroscopy (DRIFTS) to quantify iron-cyanide (Fe-CN) complexes in soil

Science.gov (United States)

Sut-Lohmann, Magdalena; Raab, Thomas

2017-04-01

Contaminated sites create a significant risk to human health, by poisoning drinking water, soil, air and as a consequence food. Continuous release of persistent iron-cyanide (Fe-CN) complexes from various industrial sources poses a high hazard to the environment and indicates the necessity to analyze considerable amount of samples. At the present time quantitative determination of Fe-CN concentration in soil usually requires a time consuming two step process: digestion of the sample (e.g., micro distillation system) and its analytical detection performed, e.g., by automated spectrophotometrical flow injection analysis (FIA). In order to determine the feasibility of diffuse reflectance infrared Fourier spectroscopy (DRIFTS) to quantify the Fe-CN complexes in soil matrix, 42 soil samples were collected (8 to 12.520 mg kg-1CN) indicating single symmetrical CN band in the range 2092 - 2084 cm-1. Partial least squares (PLS) calibration-validation model revealed IR response to CNtot exceeding 1268 mg kg-1 (limit of detection, LOD). Subsequently, leave-one-out cross-validation (LOO-CV) was performed on soil samples containing low CNtot (900 mg kg-1 resulted in LOD equal to 3494 mg kg-1. Our results indicate that spectroscopic data in combination with PLS statistics can efficiently be used to predict Fe-CN concentrations in soil. We conclude that the protocol applied in this study can strongly reduce the time and costs essential for the spatial and vertical screening of the site affected by complexed Fe-CN.

Crystallization history of enriched shergottites from Fe and Mg isotope fractionation in olivine megacrysts

Science.gov (United States)

Collinet, Max; Charlier, Bernard; Namur, Olivier; Oeser, Martin; Médard, Etienne; Weyer, Stefan

2017-06-01

Martian meteorites are the only samples available from the surface of Mars. Among them, olivine-phyric shergottites are basalts containing large zoned olivine crystals with highly magnesian cores (Fo 70-85) and rims richer in Fe (Fo 45-60). The Northwest Africa 1068 meteorite is one of the most primitive "enriched" shergottites (high initial 87Sr/86Sr and low initial ε143Nd). It contains olivine crystals as magnesian as Fo 77 and is a major source of information to constrain the composition of the parental melt, the composition and depth of the mantle source, and the cooling and crystallization history of one of the younger magmatic events on Mars (∼180 Ma). In this study, Fe-Mg isotope profiles analyzed in situ by femtosecond-laser ablation MC-ICP-MS are combined with compositional profiles of major and trace elements in olivine megacrysts. The cores of olivine megacrysts are enriched in light Fe isotopes (δ56FeIRMM-14 = -0.6 to -0.9‰) and heavy Mg isotopes (δ26MgDSM-3 = 0-0.2‰) relative to megacryst rims and to the bulk martian isotopic composition (δ56Fe = 0 ± 0.05‰, δ26Mg = -0.27 ± 0.04‰). The flat forsterite profiles of megacryst cores associated with anti-correlated fractionation of Fe-Mg isotopes indicate that these elements have been rehomogenized by diffusion at high temperature. We present a 1-D model of simultaneous diffusion and crystal growth that reproduces the observed element and isotope profiles. The simulation results suggest that the cooling rate during megacryst core crystallization was slow (43 ± 21 °C/year), and consistent with pooling in a deep crustal magma chamber. The megacryst rims then crystallized 1-2 orders of magnitude faster during magma transport toward the shallower site of final emplacement. Megacryst cores had a forsterite content 3.2 ± 1.5 mol% higher than their current composition and some were in equilibrium with the whole-rock composition of NWA 1068 (Fo 80 ± 1.5). NWA 1068 composition is thus close to a

Density functional theory study of small X-doped Mg(n) (X = Fe, Co, Ni, n = 1-9) bimetallic clusters: equilibrium structures, stabilities, electronic and magnetic properties.

Science.gov (United States)

Kong, Fanjie; Hu, Yanfei

2014-03-01

The geometries, stabilities, and electronic and magnetic properties of Mg(n) X (X = Fe, Co, Ni, n = 1-9) clusters were investigated systematically within the framework of the gradient-corrected density functional theory. The results show that the Mg(n)Fe, Mg(n)Co, and Mg(n)Ni clusters have similar geometric structures and that the X atom in Mg(n)X clusters prefers to be endohedrally doped. The average atomic binding energies, fragmentation energies, second-order differences in energy, and HOMO-LUMO gaps show that Mg₄X (X = Fe, Co, Ni) clusters possess relatively high stability. Natural population analysis was performed and the results showed that the 3s and 4s electrons always transfer to the 3d and 4p orbitals in the bonding atoms, and that electrons also transfer from the Mg atoms to the doped atoms (Fe, Co, Ni). In addition, the spin magnetic moments were analyzed and compared. Several clusters, such as Mg₁,₂,₃,₄,₅,₆,₈,₉Fe, Mg₁,₂,₄,₅,₆,₈,₉Co, and Mg₁,₂,₅,₆,₇,₉Ni, present high magnetic moments (4 μ(B), 3 μ(B), and 2 μ(B), respectively).

Determination of Mn, Fe, and Cu in chemically-treated wood pulps by the XRF addition method

Energy Technology Data Exchange (ETDEWEB)

Raemoe, J.; Klasila, T.; Piepponen, S. [VTT Chemical Technology (Finland); Sillanpaeae, M. [Oulu Univ. (Finland)

2001-08-01

A rapid X-ray fluorescence addition method has been developed for quantification of the technically most important metals in wood pulp matrix (Mn, Fe, and Cu). Pretreatment consisted of just two steps: first, acid was added to the sample to achieve homogeneous distribution of the metals; the pulp was then pressed lightly on to Mylar film. Total analysis time was less than 10 min. The concentration range investigated was up to 15 mg kg{sup -1} for Mn and up to 5 mg kg{sup -1} for Fe and Cu. Metal concentrations in Scandinavian pulps are not expected to exceed these amounts. The quantification limit was 2 mg kg{sup -1} for all three metals. The reproducibilities and repeatabilities were concentration-dependent and varied between 3 and 19% and between 1 and 17%, respectively. The squares of the linear correlation coefficients between measured intensity and added metal concentration were 0.994, 0.950, and 0.932 for Mn, Fe, and Cu, respectively. (orig.)

Negative tunneling magnetoresistance of Fe/MgO/NiO/Fe magnetic tunnel junction: Role of spin mixing and interface state

Science.gov (United States)

Zhang, Y.; Yan, X. H.; Guo, Y. D.; Xiao, Y.

2017-08-01

Motivated by a recent tunneling magnetoresistance (TMR) measurement in which the negative TMR is observed in MgO/NiO-based magnetic tunnel junctions (MTJs), we have performed systematic calculations of transmission, current, and TMR of Fe/MgO/NiO/Fe MTJ with different thicknesses of NiO and MgO layers based on noncollinear density functional theory and non-equilibrium Green's function theory. The calculations show that, as the thickness of NiO and MgO layers is small, the negative TMR can be obtained which is attributed to the spin mixing effect and interface state. However, in the thick MTJ, the spin-flipping scattering becomes weaker, and thus, the MTJs recover positive TMR. Based on our theoretical results, we believe that the interface state at Fe/NiO interface and the spin mixing effect induced by noncollinear interfacial magnetization will play important role in determining transmission and current of Fe/MgO/NiO/Fe MTJ. The results reported here will be important in understanding the electron tunneling in MTJ with the barrier made by transition metal oxide.

Gradiente radial de [Mg/Fe] em duas galáxias elípticas

Science.gov (United States)

Milone, A.; Capelato, H.

2003-08-01

Basicamente, são propostos dois cenários de evolução quí mio-dinâmico para os sistemas esferoidais: (i) o hierárquico através da fusão e/ou acresção de sub-sistemas com ou sem surtos de formação estelar, e (ii) o colapso monolí tico dissipativo com formação estelar interrompida por um vento galáctico. Ambos, dentro de certos limites, conseguem explicar os gradientes internos de metalicidade estelar presentes nas galáxias elí pticas bem como a relação observada entre a metalicidade central e a massa (Mg20 vs. log sv0). No entanto, nenhum prevê uma variação interna para a razão de abundâncias Mg/Fe que indiretamente define a escala temporal da formação estelar. Empregamos a espectroscopia óptica de fenda longa com a finalidade de recuperar as histórias de formação estelar, de enriquecimento quí mico e da dinâmica dentro de determinadas regiões das galáxias. Os espectros de média resolução (FWHM = 7,1 Å) e escala angular de 1,092 arcsec/pixel foram coletados com o telescópio 1,60m do OPD/LNA. Comparamos nossas medidas de linhas de absorção com resultados espectrofotométricos de modelos de populações estelares simples - mais especificamente os í ndices do Sistema Lick como Mg2, Mg b, e Hb - a fim de se investigar as variações internas de [Fe/H], [Mg/Fe] e idade. Para duas galáxias elí pticas, NGC 1052 e NGC 7796, pertencentes a ambientes de baixa densidade, encontramos uma variação radial da razão Mg/Fe decrescente do centro para fora em regiões de 0,6 e 1 raio efetivo respectivamente. Discutimos alguns cenários de enriquecimento quí mico para estas duas galáxias.

Epitaxial growth of bcc-FexCo100-x thin films on MgO(1 1 0) single-crystal substrates

International Nuclear Information System (INIS)

Ohtake, Mitsuru; Nishiyama, Tsutomu; Shikada, Kouhei; Kirino, Fumiyoshi; Futamoto, Masaaki

2010-01-01

Fe x Co 100-x (x=100, 65, 50 at%) epitaxial thin films were prepared on MgO(1 1 0) single-crystal substrates heated at 300 deg. C by ultra-high vacuum molecular beam epitaxy. The film structure and the growth mechanism are discussed. FeCo(2 1 1) films with bcc structure grow epitaxially on MgO(1 1 0) substrates with two types of variants whose orientations are rotated around the film normal by 180 deg. each other for all compositions. Fe x Co 100-x film growth follows the Volmer Weber mode. X-ray diffraction analysis indicates the out-of-plane and the in-plane lattice spacings are in agreement with the values of respective bulk Fe x Co 100-x crystals with very small errors less than ±0.4%, suggesting the strains in the films are very small. High-resolution cross-sectional transmission electron microscopy shows that periodical misfit dislocations are preferentially introduced in the film at the Fe 50 Co 50 /MgO interface along the MgO[1 1-bar 0] direction. The presence of such periodical dislocations decreases the large lattice mismatch of about -17% existing at the FeCo/MgO interface along the MgO[1 1-bar 0] direction.

Spin-glass behavior in single crystals of hetero-metallic magnetic warwickites MgFeBO{sub 4,} Mg{sub 0.5}Co{sub 0.5}FeBO{sub 4,} and CoFeBO{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Arauzo, A., E-mail: aarauzo@unizar.es [Servicio de Medidas Físicas, Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza (Spain); Kazak, N.V. [L.V. Kirensky Institute of Physics, SB of RAS, 660036 Krasnoyarsk (Russian Federation); Ivanova, N.B. [Siberian Federal University, 660074 Krasnoyarsk (Russian Federation); Platunov, M.S. [L.V. Kirensky Institute of Physics, SB of RAS, 660036 Krasnoyarsk (Russian Federation); Knyazev, Yu.V. [Siberian Federal University, 660074 Krasnoyarsk (Russian Federation); Bayukov, O.A.; Bezmaternykh, L.N. [L.V. Kirensky Institute of Physics, SB of RAS, 660036 Krasnoyarsk (Russian Federation); Lyubutin, I.S.; Frolov, K.V. [Shubnikov Institute of Crystallography, RAS, 119333 Moscow (Russian Federation); Ovchinnikov, S.G. [L.V. Kirensky Institute of Physics, SB of RAS, 660036 Krasnoyarsk (Russian Federation); Siberian Federal University, 660074 Krasnoyarsk (Russian Federation); Siberian State Aerospace University, 660014 Krasnoyarsk (Russian Federation); Bartolomé, J. [Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza and Departamento de Física de la Materia Condensada, 50009 Zaragoza (Spain)

2015-10-15

Magnetic properties of heterometallic warwickites MgFeBO{sub 4,} Mg{sub 0.5}Co{sub 0.5}FeBO{sub 4,} and CoFeBO{sub 4} are presented, highlighting the effect of Co substitution on the magnetic properties of these compounds. The analysis of magnetization and heat capacity data has shown that these compounds exhibit a spin-glass transition below T{sub SG}=10, 20 and 22 K, respectively. Using zero field ac susceptibility as entanglement witness we find that the low dimensional magnetic behavior above T{sub SG} show quantum entanglement behavior χ(Τ)∝T{sup −α(Τ)} up to T{sub E}≈130 K. The α parameters have been deduced as a function of temperature and Co content, indicating the existence of random singlet phase in this temperature region. Above T{sub E} the paramagnetism is interpreted in terms of non-entangled spins giving rise to Curie–Weiss paramagnetism. The different intra- and inter-ribbon exchange interaction pathways have been calculated within a simple indirect coupling model. It is determined that the triangular motifs in the warwickite structure, together with the competing interactions, induce frustration. The spin-glass character is explained in terms of the substitutional disorder of the Mg, Fe and Co atoms at the two available crystallographic sites, and the frustration induced by the competing interactions. The Co substitution induces uniaxial anisotropy, increases the absolute magnetization and increases the spin-glass freezing temperature. The entanglement behavior is supported in the intermediate phase irrespective of the introduction of anisotropy by the Co substitution. - Highlights: • Spin-glass transition of MgFeBO{sub 4,} Mg{sub 0.5}Co{sub 0.5}FeBO{sub 4,} and CoFeBO{sub 4}. • Anisotropy and transition temperature T{sub SG} increases with Co substitution. • Dynamical scaling theory near T{sub SG} is fulfilled. • Quantum entanglement is observed in between T{sub SG} and T{sub E}=130 K. • Low dimensional random singlet phase

Examination of the magnetic hyperthermia and other magnetic properties of CoFe2O4@MgFe2O4 nanoparticles using external field Mössbauer spectroscopy

Science.gov (United States)

Park, Jeongho; Choi, Hyunkyung; Kim, Sam Jin; Kim, Chul Sung

2018-05-01

CoFe2O4@MgFe2O4 core/shell nanoparticles were synthesized by high temperature thermal decomposition with seed-mediated growth. The crystal structure and magnetic properties of the nanoparticles were investigated using X-ray diffractometry (XRD), vibrating sample magnetometry (VSM), and Mössbauer spectrometry. The magnetic hyperthermia properties were investigated using a MagneTherm device. Analysis of the XRD patterns showed that CoFe2O4@MgFe2O4 had a cubic spinel crystal structure with space group Fd-3m and a lattice constant (a0) of 8.3686 Å. The size and morphology of the CoFe2O4@MgFe2O4 nanoparticles were confirmed by HR-TEM. The VSM measurements showed that the saturation magnetization (MS) of CoFe2O4@MgFe2O4 was 77.9 emu/g. The self-heating temperature of CoFe2O4@MgFe2O4 was 37.8 °C at 112 kHz and 250 Oe. The CoFe2O4@MgFe2O4 core/shell nanoparticles showed the largest saturation magnetization value, while their magnetic hyperthermia properties were between those of the CoFe2O4 and MgFe2O4 nanoparticles. In order to investigate the hyperfine interactions of CoFe2O4, MgFe2O4, and CoFe2O4@MgFe2O4, we performed Mössbauer spectrometry at various temperatures. In addition, Mössbauer spectrometry of CoFe2O4@MgFe2O4 was performed at 4.2 K with applied fields of 0-4.5 T, and the results were analyzed with sextets for the tetrahedral A-site and sextets for the octahedral B-site.

Effect of annealing on microstructure evolution in CoFeB/MgO/CoFeB heterostructures by positron annihilation

Science.gov (United States)

Zhao, Chong-Jun; Lu, Xiang-An; Zhao, Zhi-Duo; Li, Ming-Hua; Zhang, Peng; Wang, Bao-Yi; Cao, Xing-Zhong; Zhang, Jing-Yan; Yu, Guang-Hua

2013-09-01

As one of the most powerful tools for investigation of defects of materials, positron annihilation spectroscopy was employed to explore the thermal effects on the film microstructure evolution in CoFeB/MgO/CoFeB heterostructures. It is found that high annealing temperature can drive vacancy defects agglomeration and ordering acceleration in the MgO barrier. Meanwhile, another important type of defects, vacancy clusters, which are formed via the agglomeration of vacancy defects in the MgO barrier after annealing, still exists inside the MgO barrier. All these behaviors in the MgO barrier could potentially impact the overall performance in MgO based magnetic tunnel junctions.

Conscious Sedation Efficacy of 0.3 and 0.5 mg/kg Oral Midazolam for Three to Six Year-Old Uncooperative Children Undergoing Dental Treatment: A Clinical Trial

Directory of Open Access Journals (Sweden)

Masoud Fallahinejad Ghajari

2016-10-01

Full Text Available Objectives: Midazolam with variable dosages has been used to induce sedation in pediatric dentistry. The aim of this study was to compare the efficacy of two dosages of oral midazolam for conscious sedation of children undergoing dental treatment.Materials and Methods: In this randomized crossover double blind clinical trial, 20 healthy children (ASA I aged three to six years with negative or definitely negative Frankl behavioral rating scale were evaluated. Half of the children received 0.5mg/kg oral midazolam plus 1mg/kg hydroxyzine (A orally in the first session and 0.3mg/kg oral midazolam plus 1mg/kg hydroxyzine (B in the next session. The other half received the drugs on a reverse order. Sedation degree by Houpt sedation rating scale, heart rate and level of SpO2 were assessed at the beginning and after 15 and 30 minutes. The data were analyzed using SPSS 19 and Wilcoxon Signed Rank and McNemar’s tests.Results: The results showed that although administration of 0.5mg/kg oral midazolam was slightly superior to 0.3mg/kg oral midazolam in terms of sedation efficacy, the differences were not significant (P>0.05. The difference in treatment success was not significant either (P>0.05. Heart rate, oxygen saturation (SpO2 and respiratory rate were within the normal range and did not show a significant change (P>0.05.Conclusions: The overall success rate of the two drug combinations namely 0.5mg/kg oral midazolam plus hydroxyzine and 0.3mg/kg oral midazolam plus hydroxyzine was not significantly different for management of pediatric patients.Keywords: Conscious Sedation; Pediatric Dentistry; Midazolam; Hydroxyzine

FeGa/MgO/Fe/GaAs(001) magnetic tunnel junction: Growth and magnetic properties

International Nuclear Information System (INIS)

Gobaut, B.; Ciprian, R.; Salles, B.R.; Krizmancic, D.; Rossi, G.; Panaccione, G.; Eddrief, M.; Marangolo, M.; Torelli, P.

2015-01-01

Research on spintronics and on multiferroics leads now to the possibility of combining the properties of these materials in order to develop new functional devices. Here we report the integration of a layer of magnetostrictive material into a magnetic tunnel junction. A FeGa/MgO/Fe heterostructure has been grown on a GaAs(001) substrate by molecular beam epitaxy (MBE) and studied by X-ray magnetic circular dichroism (XMCD). The comparison between magneto optical Kerr effect (MOKE) measurements and hysteresis performed in total electron yield allowed distinguishing the ferromagnetic hysteresis loop of the FeGa top layer from that of the Fe buried layer, evidencing a different switching field of the two layers. This observation indicates an absence of magnetic coupling between the two ferromagnetic layers despite the thickness of the MgO barrier of only 2.5 nm. The in-plane magnetic anisotropy has also been investigated. Overall results show the good quality of the heterostructure and the general feasibility of such a device using magnetostrictive materials in magnetic tunnel junction

The effect of Fe-rich intermetallics on the microstructure, hardness and tensile properties of Al–Mg2Si die-cast composite

International Nuclear Information System (INIS)

Emamy, M.; Emami, A.R.; Khorshidi, R.; Ghorbani, M.R.

2013-01-01

Highlights: ► Effect of Fe on the microstructure and mechanical properties of Al–Mg 2 Si composite. ► Fe changed the size of primary Mg 2 Si from 33 μm to 15 μm. ► Higher hardness, YS, UTS and Quality Index values obtained from Fe addition. ► Different morphologies of Fe-intermetallics were found with higher Fe contents. - Abstract: In present paper, an attempt was made to examine the effect of different concentrations of Fe (0.5, 1, 1.5, 2 and 3 wt.%) on the microstructure and tensile properties of an in situ Al–15wt.%Mg 2 Si metal matrix composite (MMC). The composite was made by casting process and characterized by optical microscope, scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy. The results depicted that the addition of 2 wt.% Fe to the MMC changes the morphology of primary Mg 2 Si from irregular to polyhedral shape and reduces its average particle size from 33 μm to 15 μm. The microstructural studies also showed that the addition of Fe leads to the formation of Fe-rich intermetallics with polyhedral, plate-like and star-like morphology. Hardness results demonstrated that Fe addition to Al–15%Mg 2 Si composite has a positive effect on the hardness improvement. Further investigations on tensile tests revealed optimum Fe (1 wt.%) level for improving tensile properties. In the point of fracture behavior of the composite, Fe-containing specimens showed a brittle mode of failure

Thick CoFeB with perpendicular magnetic anisotropy in CoFeB-MgO based magnetic tunnel junction

Directory of Open Access Journals (Sweden)

V. B. Naik

2012-12-01

Full Text Available We have investigated the effect of an ultra-thin Ta insertion in the CoFeB (CoFeB/Ta/CoFeB free layer (FL on magnetic and tunneling magnetoresistance (TMR properties of a CoFeB-MgO system with perpendicular magnetic anisotropy (PMA. It is found that the critical thickness (tc to sustain PMA is doubled (tc = 2.6 nm in Ta-inserted CoFeB FL as compared to single CoFeB layer (tc = 1.3 nm. While the effective magnetic anisotropy is found to increase with Ta insertion, the saturation magnetization showed a slight reduction. As the CoFeB thickness increasing, the thermal stability of Ta inserted structure is significantly increased by a factor of 2.5 for total CoFeB thickness less than 2 nm. We have observed a reasonable value of TMR for a much thicker CoFeB FL (thickness = 2-2.6 nm with Ta insertion, and without significant increment in resistance-area product. Our results reveal that an ultra-thin Ta insertion in CoFeB might pay the way towards developing the high-density memory devices with enhanced thermal stability.

High magnetic coercivity of FePt-Ag/MgO granular nanolayers

Science.gov (United States)

Roghani, R.; Sebt, S. A.; Khajehnezhad, A.

2018-06-01

L10-FePt ferromagnetic nanoparticles have a hight coercivity of Tesla order. Thus, these nanoparticles, with size of 10 to 15 nm and uniform surface distribution, are suitable in magnetic data storage technology with density of more than 1GB. In order to improve structural and magnetic properties of FePt nanoparticles, some elements and combinations have been added to compound. In this research, we show that due to the presence of the Ag, the phase transition temperature of FePt from fcc to L10-fct phase decreases. The presence of Ag as an additive in FePt-Ag nanocomposite, increases the magnetic coercivity. This nanocomposite, with 10% Ag, was deposited by magnetron sputtering on the MgO heat layer. VSM results of 10 nm nanoparticles show that coercivity has increased up to 1.4 T. XRD and FESEM results confirm that the size of the L10-FePt nanoparticles are 10 nm and their surface distribution are uniform. Ag gradually form nano scale clusters with separate lattice and FePt-Ag nanocomposite appears. The result of this process is emptiness of Ag position in FePt-fcc lattice. So, the mobility of Fe and Pt atoms in this lattice increases and it can be possible for them to move in lower temperature. This mechanism explain the effect of Ag on decreasing the transition temperature to fct-L10 phase, and hight coercivity of FePt nanoparticles.

Adsorption of arsenate on Cu/Mg/Fe/La layered double hydroxide from aqueous solutions

Energy Technology Data Exchange (ETDEWEB)

Guo, Yanwei [State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Zhu, Zhiliang, E-mail: zzl@tongji.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Qiu, Yanling [Key Laboratory of Yangtze River Water Environment, Ministry of Education, Tongji University, Shanghai 200092 (China); Zhao, Jianfu [State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China)

2012-11-15

Highlights: Black-Right-Pointing-Pointer A novel layered double hydroxide containing lanthanum (Cu/Mg/Fe/La-LDH) has been synthesized. Black-Right-Pointing-Pointer The average pore size of the materials with about 16 nm indicated that the mesoporous structures existed in the Cu/Mg/Fe/La-LDHs. Black-Right-Pointing-Pointer The adsorption capacity of As(V) increased with the increment of La{sup 3+} content in the LDH. Black-Right-Pointing-Pointer The maximum adsorption capacity of the synthesized Cu/Mg/Fe/La-LDH for arsenate was 43.5 mg/g. - Abstract: A novel layered double hydroxide containing lanthanum (Cu/Mg/Fe/La-LDH) has been synthesized and used for the removal of arsenate from aqueous solutions. The purpose of incorporation of La{sup 3+} into LDHs was tried to enhance the uptake efficiency of arsenate and broaden the application field of LDHs functional materials. Effects of various physico-chemical factors such as solution pH, adsorbent dosage, contact time and initial arsenate concentrations on the adsorption of arsenate onto Cu/Mg/Fe/La-LDH were investigated. Results showed that the removal efficiency of arsenate increased with the increment of the lanthanum content in Cu/Mg/Fe/La-LDH adsorbents, and the optimized lanthanum content was 20% of the total trivalent metals composition (Fe{sup 3+} and La{sup 3+}). The adsorption isotherms can be well described by Langmuir equation, and the adsorption kinetics of arsenate followed the pseudo-second-order kinetic model. Coexistent ions such as HPO{sub 4}{sup 2-}, CO{sub 3}{sup 2-}, SO{sub 4}{sup 2-}, Cl{sup -} and NO{sub 3}{sup -} exhibited obvious competition with arsenate for the adsorption on Cu/Mg/Fe/La-LDH. The solution pH significantly affected the removal efficiency, which was closely related to the change of arsenate species distribution under different pH conditions. The predominant adsorption mechanism can be mainly attributed to the processes including ion exchange and layer ligand exchange.

Adsorption of arsenate on Cu/Mg/Fe/La layered double hydroxide from aqueous solutions

International Nuclear Information System (INIS)

Guo, Yanwei; Zhu, Zhiliang; Qiu, Yanling; Zhao, Jianfu

2012-01-01

Highlights: ► A novel layered double hydroxide containing lanthanum (Cu/Mg/Fe/La-LDH) has been synthesized. ► The average pore size of the materials with about 16 nm indicated that the mesoporous structures existed in the Cu/Mg/Fe/La-LDHs. ► The adsorption capacity of As(V) increased with the increment of La 3+ content in the LDH. ► The maximum adsorption capacity of the synthesized Cu/Mg/Fe/La-LDH for arsenate was 43.5 mg/g. - Abstract: A novel layered double hydroxide containing lanthanum (Cu/Mg/Fe/La-LDH) has been synthesized and used for the removal of arsenate from aqueous solutions. The purpose of incorporation of La 3+ into LDHs was tried to enhance the uptake efficiency of arsenate and broaden the application field of LDHs functional materials. Effects of various physico-chemical factors such as solution pH, adsorbent dosage, contact time and initial arsenate concentrations on the adsorption of arsenate onto Cu/Mg/Fe/La-LDH were investigated. Results showed that the removal efficiency of arsenate increased with the increment of the lanthanum content in Cu/Mg/Fe/La-LDH adsorbents, and the optimized lanthanum content was 20% of the total trivalent metals composition (Fe 3+ and La 3+ ). The adsorption isotherms can be well described by Langmuir equation, and the adsorption kinetics of arsenate followed the pseudo-second-order kinetic model. Coexistent ions such as HPO 4 2− , CO 3 2− , SO 4 2− , Cl − and NO 3 − exhibited obvious competition with arsenate for the adsorption on Cu/Mg/Fe/La-LDH. The solution pH significantly affected the removal efficiency, which was closely related to the change of arsenate species distribution under different pH conditions. The predominant adsorption mechanism can be mainly attributed to the processes including ion exchange and layer ligand exchange.

First-principles investigation of Fe-doped MgSiO3-ilmenite

International Nuclear Information System (INIS)

Stashans, Arvids; Rivera, Krupskaya; Pinto, Henry P.

2012-01-01

First principles density functional theory and generalised gradient approximation (GGA) have been exploited to investigate Fe-doped ilmenite-type MgSiO 3 mineral. Strong electron correlation effects not included in a density-functional formalism are described by a Hubbard-type on-site Coulomb repulsion (the DFT+U approach). Microstructure of equilibrium geometries, electronic band structures as well as magnetic properties are computed and discussed in detail. Hartree-Fock methodology is used as an extra tool to study optical properties of the same system. For equilibrium state of the doped mineral we find zigzag-type atomic rearrangements around the Fe impurity. The inclusion of correlation effects leads to an improved description of the electronic properties. In particular, it is discovered that Fe incorporation produces local energy levels within the band-gap of the material. Using ΔSCF method optical absorption energies are found to be equal to 2.2 and 2.6 eV leading to light absorption at longer wavelengths compared to the undoped MgSiO 3 . Our results provide evidence on the occurrence of local magnetic moment in the region surrounding iron dopant. According to the outcomes, the Fe⇒Mg reaction can be described as substitutionally labile with Fe 2+ complex being found in the high-spin state at low pressure MgSiO 3 -ilmenite conditions.

First-principles investigation of Fe-doped MgSiO{sub 3}-ilmenite

Energy Technology Data Exchange (ETDEWEB)

Stashans, Arvids, E-mail: arvids@utpl.edu.ec [Grupo de Fisicoquimica de Materiales, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Rivera, Krupskaya [Grupo de Fisicoquimica de Materiales, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Escuela de Geologia y Minas, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Pinto, Henry P. [Interdisciplinary Center for Nanotoxicity, Department of Chemistry, Jackson State University, Jackson, Mississippi 39217-0510 (United States)

2012-06-15

First principles density functional theory and generalised gradient approximation (GGA) have been exploited to investigate Fe-doped ilmenite-type MgSiO{sub 3} mineral. Strong electron correlation effects not included in a density-functional formalism are described by a Hubbard-type on-site Coulomb repulsion (the DFT+U approach). Microstructure of equilibrium geometries, electronic band structures as well as magnetic properties are computed and discussed in detail. Hartree-Fock methodology is used as an extra tool to study optical properties of the same system. For equilibrium state of the doped mineral we find zigzag-type atomic rearrangements around the Fe impurity. The inclusion of correlation effects leads to an improved description of the electronic properties. In particular, it is discovered that Fe incorporation produces local energy levels within the band-gap of the material. Using {Delta}SCF method optical absorption energies are found to be equal to 2.2 and 2.6 eV leading to light absorption at longer wavelengths compared to the undoped MgSiO{sub 3}. Our results provide evidence on the occurrence of local magnetic moment in the region surrounding iron dopant. According to the outcomes, the Fe Rightwards-Double-Arrow Mg reaction can be described as substitutionally labile with Fe{sup 2+} complex being found in the high-spin state at low pressure MgSiO{sub 3}-ilmenite conditions.

Multivariate approach to assess in vitro Fe bioaccessibility in chicken meat

Directory of Open Access Journals (Sweden)

Náira da Silva CAMPOS

Full Text Available Abstract A 32 factorial design was employed to develop an in vitro digestion method for estimation of Fe bioaccessible fractions in cooked chicken meat. The effects of sample size and the in vitro bioaccessible fractions of this essential element were evaluated. A sample preparation method employing a microwave assisted digestion with dilute nitric acid was used prior to total Fe determination. For the bioacessibility studies, the optimized procedure employed 7.5 g of sample and 6% w/v of an acid pepsin solution. This procedure was applied to two kinds of chicken meat samples: breast and liver. Flame Atomic Absorption Spectrometry was used to determine total and bioaccessible (chyme or soluble portion levels of iron in the samples. With respect to total Fe content, the bioaccessible fractions of Fe found in these samples were around 23% and 56 %, for breast and chicken liver, respectively. The chicken liver sample showed the highest total (400 ± 10 mg kg-1 and bioaccessible Fe contents (223 ± 18 mg kg-1 and stands out as a good source of this micronutrient.

The effects of Fe2O3 nanoparticles on MgB2 superconducting thin films

International Nuclear Information System (INIS)

Koparan, E.T.; Sidorenko, A.; Yanmaz, E.

2013-01-01

Full text: Since the discovery of superconductivity in binary MgB 2 compounds, extensive studies have been carried out because of its excellent properties for technological applications, such as high transition temperature (T c = 39 K), high upper critical field (H c2 ), high critical current density (J c ). Thin films are important for fundamental research as well as technological applications of any functional materials. Technological applications primarily depend on critical current density. The strong field dependence of J c for MgB 2 necessitates an enhancement in flux pinning performance in order to improve values in high magnetic fields. An effective way to improve the flux pinning is to introduce flux pinning centers into MgB 2 through a dopant having size comparable to the coherence length of MgB 2 . In this study, MgB 2 film with a thickness of about 600 nm was deposited on the MgO (100) single crystal substrate using a 'two-step' synthesis technique. Firstly, deposition of boron thin film was carried out by rf magnetron sputtering on MgO substrates and followed by a post deposition annealing at 850 degrees Celsius in magnesium vapour. In order to investigate the effect of Fe 2 O 3 nanoparticles on the structural and magnetic properties of films, MgB 2 films were coated with different concentrations of Fe 2 O 3 nanoparticles by a spin coating process. The effects of different concentrations of ferromagnetic Fe 2 O 3 nanoparticles on superconducting properties of obtained films were carried out by using structural (XRD, SEM, AFM), electrical (R-T) and magnetization (M-H, M-T and AC Susceptibility) measurements. It was calculated that anisotropic coefficient was about γ = 1.2 and coherence length of 5 nm for the uncoated film. As a result of coherence length, the appropriate diameters of Fe 2 O 3 nanoparticles were found to be 10 nm, indicating that these nanoparticles served as the pinning centers. Based on the data obtained from this study, it can be

Structural characterization of Mg substituted on A/B sites in NiFe_2O_4 nanoparticles using autocombustion method

Science.gov (United States)

De, Manojit; Tewari, H. S.

2017-07-01

In the present paper, we are reporting the synthesis of pure nickel and magnesium ferrite [NiFe_2O_4, MgFe_2O_4] and magnesium-substituted nickel ferrite (Ni_{1-x}Mg_{x/y}Fe_{2-y}O_4; x=y=0.60) on A/B sites with particles size in nanometer range using autocombustion technique. In this study, it has been observed that with increase in sintering temperature, the estimated bulk density of the materials increases. The XRD patterns of the samples show the formation of single-phase materials and the lattice parameters are estimated from XRD patterns. From Raman spectra, the Raman shift of pure NiFe_2O_4 and MgFe_2O_4 are comparable with the experimental values reported in literature. The Raman spectra give five Raman active modes (A_{{1g}} + Eg + 3F_{2g}) which are expected in the spinel structure.

Spin-glass behavior of warwickite MgFeBO{sub 4} and CoFeBO{sub 4} crystals observed by Mössbauer spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Lyubutin, I.S.; Korotkov, N. Yu.; Frolov, K.V. [Shubnikov Institute of Crystallography, RAS, 119333 Moscow (Russian Federation); Kazak, N.V.; Platunov, M.S. [Kirensky Institute of Physics, SB of RAS, 660036 Krasnoyarsk (Russian Federation); Knyazev, Yu. V. [Siberian Federal University, 660074 Krasnoyarsk (Russian Federation); Bezmaternykh, L.N. [Kirensky Institute of Physics, SB of RAS, 660036 Krasnoyarsk (Russian Federation); Ovchinnikov, S.G. [Kirensky Institute of Physics, SB of RAS, 660036 Krasnoyarsk (Russian Federation); Siberian Federal University, 660074 Krasnoyarsk (Russian Federation); Siberian State Aerospace University, 660014 Krasnoyarsk (Russian Federation); Arauzo, A. [Servicio de Medidas Físicas, Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza (Spain); Bartolomé, J. [Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza and Departamento de Física de la Materia Condensada, 50009 Zaragoza (Spain)

2015-09-05

Highlights: • Spin-glass behavior of MgFeBO{sub 4} and CoFeBO{sub 4} observed by Mössbauer spectroscopy. • Transition temperature T{sub SG} increases strongly with Co substitution. • Dynamical scaling theory near T{sub SG} is fulfilled. • Spin-glass behavior is explained as due to short range correlations. • Inclusion of Co increases exchange interaction and magnetocrystalline anisotropy. - Abstract: Single crystals of MgFeBO{sub 4} and CoFeBO{sub 4} warwickites were obtained. The effects of charge ordering and magnetic properties were investigated by Mössbauer spectroscopy. Cation distribution over M1 and M2 nonequivalent sites and the average charge at the metal positions were established. Low temperature Mössbauer spectra reveal spin-glass behavior, with spin-freezing temperatures T{sub SG} of 15.2 and 33.2 K for Mg- and Co-warwickites, respectively, higher than that observed from the d.c. and a.c. magnetic susceptibility measurements. The difference is explained in terms of dynamical scaling theory. The specific shape of the Mössbauer spectra in the vicinity of the magnetic transition at T{sub SG} shows the difference between spin-glass and superparamagnetic behavior and demonstrates an overwhelming role of the exchange anisotropy in the properties of Mg-warwickite. In Co-warwickite the increase of magnetocrystalline anisotropy provokes an increase in magnetic viscosity.

First-Principles Study of Enhanced Magnetoelectric Effects at the Fe/MgO(001) Interface

Science.gov (United States)

Niranjan, M. K.; Jaswal, S. S.; Tsymbal, E. Y.; Duan, C.-G.

2010-03-01

The magnetoelectric effect allows affecting magnetic properties of materials by electric fields with potential for technological applications such as electrically controlled magnetic data storage. In this study we explore, using first-principles methods, the magnetoelectric effect at the Fe/MgO(001) interface^,1. By explicitly introducing an electric field in our density-functional calculations we demonstrate that the magnetic moment of Fe atoms at the interface changes linearly as a function of the applied electric field with the surface magnetoelectric coefficient being strongly enhanced as compared to that for the clean Fe(001) surface.^1 The effect originates from the increased screening charge associated with a large dielectric constant of MgO. The influence of electric field on relative occupancy of the Fe-3d orbitals leads to significant change in the surface magnetocrystalline anisotropy. These results are compared with the available experimental work.^2 Our results indicate that using high-k dielectrics at the interface with ferromagnetic metals may be very effective in controlling the magnetic properties by electric fields thereby leading to interesting device applications. ^1 C.-G. Duan et al., Phys. Rev. Lett. 101, 137201 (2008). ^2 T. Maruyama et al., Nat. Nanotech., 4, 158 (2009).

Study of solid state interactions in the systems ZnFe2O4 - CaO, ZnFe2O4 - MgO and zinc cake with CaO and MgO

Directory of Open Access Journals (Sweden)

Peltekov A.B.

2013-01-01

Full Text Available The solid state interactions of CaO and MgO with synthetic and industrial ZnFe2O4 (in zinc cake have been studied using chemical, XRD analysis and Mössbauer spectroscopy. The exchange reactions in the systems ZnFe2O4 - CaO and ZnFe2O4 - MgO have been investigated in the range of 850-1200ºC and duration up to 180 min. It has been established that Ca2+ and Mg2+ ions exchange Zn2+ in ferrite partially and the solubility of zinc in a 7% sulfuric acid solution increases. The possibilities for utilization of the obtained results in zinc hydrometallurgy have been discussed.

Photocatalytic degradation of methylene blue on magnetically separable MgFe2O4 under visible light irradiation

KAUST Repository

Shahid, Muhammad

2013-05-01

A magnetically separable single-phase MgFe2O4 photocatalyst with a spinel crystal structure was synthesized by using the solid-state reaction method. The formation of spinel structure is confirmed by X-ray diffraction and Fourier transform infrared spectroscopy. The magnetic measurements showed that the photocatalyst material can be separated from water when an external magnetic field is added and redispersed into water solution after the external magnetic field is eliminated. It is one of the promising photocatalysts for waste water treatment. The photocatalytic activity of MgFe2O4 was investigated by using the photo-decomposition of methylene blue dye under visible light. The photoelectrochemical property of the MgFe2O4 was studied by measuring their photocurrent-potential behavior in 1 M NaOH electrolyte under AM 1.5100 mW cm-2 illumination. © 2013 Elsevier B.V. All rights reserved.

Spin-dependent electrical transport in Fe-MgO-Fe heterostructures

Directory of Open Access Journals (Sweden)

A A Shokri

2016-09-01

Full Text Available In this paper, spin-dependent electrical transport properties are investigated in a single-crystal magnetic tunnel junction (MTJ which consists of two ferromagnetic Fe electrodes separated by an MgO insulating barrier. These properties contain electric current, spin polarization and tunnel magnetoresistance (TMR. For this purpose, spin-dependent Hamiltonian is described for Δ1 and Δ5 bands in the transport direction. The transmission is calculated by Green's function formalism based on a single-band tight-binding approximation. The transport properties are investigated as a function of the barrier thickness in the limit of coherent tunneling. We have demonstrated that dependence of the TMR on the applied voltage and barrier thickness. Our numerical results may be useful for designing of spintronic devices. The numerical results may be useful in designing of spintronic devices.

Gas response properties of citrate gel synthesized nanocrystalline MgFe2O4: Effect of sintering temperature

International Nuclear Information System (INIS)

Patil, J.Y.; Mulla, I.S.; Suryavanshi, S.S.

2013-01-01

Graphical abstract: Display Omitted Highlights: ► Synthesis of nanocrystalline MgFe 2 O 4 by economical citrate gel combustion method. ► Structural, morphological, and gas response properties of MgFe 2 O 4 . ► Enhancement in selectivity of MgFe 2 O 4 towards LPG with sintering temperature. ► Use of MgFe 2 O 4 to detect different gases at different operating temperatures. -- Abstract: Spinel type MgFe 2 O 4 material was synthesized by citrate gel combustion method. The effect of sintering temperature on structural, morphological, and gas response properties was studied. The powder X-ray diffraction pattern and transmission electron microscope study confirms nanocrystalline spinel structure of the synthesized powder. The material was tested for response properties to various reducing gases like liquid petroleum gas (LPG), acetone, ethanol, and ammonia. The results demonstrated n-type semiconducting behavior of MgFe 2 O 4 material. It was revealed that MgFe 2 O 4 sintered at 973 K was most sensitive to LPG at 648 K and to acetone at 498 K. However MgFe 2 O 4 sintered at 1173 K exhibited higher response and selectivity to LPG with marginal increase in the operating temperature. Furthermore, the sensor exhibited a fast response and a good recovery. It was observed that the particles size, porosity, and surface activity of the sensor material is affected by the sintering temperature.

Bio-inspired route for the synthesis of spherical shaped MgO:Fe(3+) nanoparticles: Structural, photoluminescence and photocatalytic investigation.

Science.gov (United States)

Anilkumar, M R; Nagaswarupa, H P; Nagabhushana, H; Sharma, S C; Vidya, Y S; Anantharaju, K S; Prashantha, S C; Shivakuamra, C; Gurushantha, K

2015-01-01

MgO:Fe(3+) (0.1-5 mol%) nanoparticles (NPs) were synthesized via eco-friendly, inexpensive and simple low temperature solution combustion route using Aloe vera gel as fuel. The final products were characterized by SEM, TEM and HRTEM. PXRD data and Rietveld analysis revealed the formation of cubic system. The influence of Fe(3+) ion concentration on the structure morphology, UV absorption, PL emission and photocatalytic activity of MgO:Fe(3+) NPs were investigated. The yellow emission with CIE chromaticity coordinates (0.44, 0.52) and average correlated color temperature value was found to be 3540 K which corresponds to warm light of NPs. The control of Fe(3+) on MgO matrix influences the photocatalytic decolorization of methylene blue (MB) under UV light. The enhanced photocatalytic activity of MgO:Fe(3+) (4 mol%) was attributed to dopant concentration, effective crystallite size, textural properties, decreased band gap and capability for reducing the electron-hole pair recombination. Further, the trends of inhibitory effect in the presence of different radical scavengers were explored. These findings open up new avenues for the exploration of Fe-doped MgO in eco-friendly water applications and in the process of display devices. Copyright © 2015 Elsevier B.V. All rights reserved.

Ion beam synthesis of Fe nanoparticles in MgO and yttria-stabilized zirconia

Science.gov (United States)

Potzger, K.; Reuther, H.; Zhou, Shengqiang; Mücklich, A.; Grötzschel, R.; Eichhorn, F.; Liedke, M. O.; Fassbender, J.; Lichte, H.; Lenk, A.

2006-04-01

To form embedded Fe nanoparticles, MgO(001) and YSZ(001) single crystals have been implanted at elevated temperatures with Fe ions at energies of 100 keV and 110 keV, respectively. The ion fluence was fixed at 6×1016 cm-2. As a result, γ- and α-phase Fe nanoparticles were synthesized inside MgO and YSZ, respectively. A synthesis efficiency of 100% has been achieved for implantation at 1273 K into YSZ. The ferromagnetic behavior of the α-Fe nanoparticles is reflected by a magnetic hyperfine field of 330 kOe and a hysteretic magnetization reversal. Electron holography showed a fringing magnetic field around some, but not all of the particles.

Ion beam synthesis of Fe nanoparticles in MgO and yttria-stabilized zirconia

International Nuclear Information System (INIS)

Potzger, K.; Reuther, H.; Zhou, Shengqiang; Muecklich, A.; Groetzschel, R.; Eichhorn, F.; Liedke, M. O.; Fassbender, J.; Lichte, H.; Lenk, A.

2006-01-01

To form embedded Fe nanoparticles, MgO(001) and YSZ(001) single crystals have been implanted at elevated temperatures with Fe ions at energies of 100 keV and 110 keV, respectively. The ion fluence was fixed at 6x10 16 cm -2 . As a result, γ- and α-phase Fe nanoparticles were synthesized inside MgO and YSZ, respectively. A synthesis efficiency of 100% has been achieved for implantation at 1273 K into YSZ. The ferromagnetic behavior of the α-Fe nanoparticles is reflected by a magnetic hyperfine field of 330 kOe and a hysteretic magnetization reversal. Electron holography showed a fringing magnetic field around some, but not all of the particles

High thermal stability in W/MgO/CoFeB/W/CoFeB/W stacks via ultrathin W insertion with perpendicular magnetic anisotropy

Energy Technology Data Exchange (ETDEWEB)

Liu, Yi; Yu, Tao [School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China); Zhu, Zhengyong; Zhong, Huicai [Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029 (China); Khamis, Khamis Masoud [School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China); Zhu, Kaigui, E-mail: kgzhu@buaa.edu.cn [School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Micro-Nano Measurement-Manipulation and Physics, Ministry of Education, Beihang University, Beijing 100191 (China)

2016-07-15

The perpendicular magnetic anisotropy (PMA) of a series of top MgO/CoFeB/W stacks were studied. In these stacks, the thickness of CoFeB is limited in a range of 1.1–2.2 nm. It was found that the stack can still maintain PMA in a 1.9 nm thick CoFeB free layer. Besides, we investigated the thermal stability factor ∆ of a spin transfer torque magnetic random access memory (STT-MRAM) by inserting an ultra-thin W film of 0.8 nm between two CoFeB films. The result shows a clear PMA behavior for the samples with CoFeB thickness up to 2.5 nm, and an in-plane magnetic anisotropy (IMA) when the CoFeB is thicker than 2.5 nm. Moreover, the thermal stability factor ∆ of the CoFeB stack with W insertion is about 132 for a 50 nm size STT-MRAM device, which is remarkably improved compared to 112 for a sample without W insertion. Our results represent an alternative way to realize the endurance at high annealing temperature, high-density and high ∆ in STT-MRAM device by ultra-thin W insertion. - Highlights: • The MgO/CoFeB/W multilayer can still maintain PMA in a CoFeB thickness of 1.9 nm. • The sample with 2.5 nm thickness of CoFeB by W insertion can still maintain PMA. • The sample with W insertion can still maintain PMA until the annealing temperature as high as 350 °C. • The thermal stability factor ∆ of sample with W insertion could be increase to about 132 for a 50 nm size STT-MRAM device.

Solubility and release of fenbufen intercalated in Mg, Al and Mg, Al, Fe layered double hydroxides (LDH): The effect of Eudragit S 100 covering

International Nuclear Information System (INIS)

Arco, M. del; Fernandez, A.; Martin, C.; Rives, V.

2010-01-01

Following different preparation routes, fenbufen has been intercalated in the interlayer space of layered double hydroxides with Mg 2+ and Al 3+ or Mg 2+ , Al 3+ and Fe 3+ in the layers. Well crystallized samples were obtained in most of the cases (intercalation was not observed by reconstruction of the MgAlFe matrix), with layer heights ranging between 16.1 and 18.8 A. The presence of the LDH increases the solubility of fenbufen, especially when used as a matrix. The dissolution rate of the drug decreases when the drug is intercalated, and is even lower in those systems containing iron; release takes place through ionic exchange with phosphate anions from the solution. Preparation of microspheres with Eudragit S 100 leads to solids with an homogeneous, smooth surface with efficient covering of the LDH surface, as drug release was not observed at pH lower than 7. - Graphical abstract: LDHs containing Mg, Al, Fe increase fenbufen solubility, release takes place through ionic exchange with phosphate anions from the medium. Spherical solids with homogeneous, smooth surface are formed when using Eudragit S 100, efficiently covering the LDH surface. Display Omitted

Nano-structure formation of Fe-Pt perpendicular magnetic recording media co-deposited with MgO, Al2O3 and SiO2 additives

International Nuclear Information System (INIS)

Safran, G.; Suzuki, T.; Ouchi, K.; Barna, P.B.; Radnoczi, G.

2006-01-01

Perpendicular magnetic recording media samples were prepared by sputter deposition on sapphire with a layer sequence of MgO seed-layer/Cr under-layer/FeSi soft magnetic under-layer/MgO intermediate layer/FePt-oxide recording layer. The effects of MgO, Al 2 O 3 and SiO 2 additives on the morphology and orientation of the FePt layer were investigated by transmission electron microscopy. The samples exhibited (001) orientation of the L1 FePt phase with the mutual orientations of sapphire substrate//MgO(100)[001]//Cr(100)[11-bar0]//FeSi(100)[11-bar0]//MgO(100) [001]//FePt(001)[100]. The morphology of the FePt films varied due to the co-deposited oxides: The FePt layers were continuous and segmented by stacking faults aligned at 54 o to the surface. Films with SiO 2 addition, beside the oriented columnar FePt grains, exhibited a fraction of misoriented crystallites due to random repeated nucleation. Al 2 O 3 addition resulted in a layered structure, i.e. an initial continuous epitaxial FePt layer covered by a secondary layer of FePt-Al 2 O 3 composite. Both components (FePt and MgO) of the MgO-added samples were grown epitaxially on the MgO intermediate layer, so that a nano-composite of intercalated (001) FePt and (001) MgO was formed. The revealed microstructures and formation mechanisms may facilitate the improvement of the structural and magnetic properties of the FePt-oxide composite perpendicular magnetic recording media

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

KAUST Repository

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

2011-01-01

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

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

Science.gov (United States)

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

2016-01-01

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

Rapid degradation of azo dye Direct Black BN by magnetic MgFe{sub 2}O{sub 4}-SiC under microwave radiation

Energy Technology Data Exchange (ETDEWEB)

Gao, Jia; Yang, Shaogui, E-mail: yangsg@nju.edu.cn; Li, Na; Meng, Lingjun; Wang, Fei; He, Huan; Sun, Cheng

2016-08-30

Highlights: • MgFe{sub 2}O{sub 4}-SiC was first successfully synthesized. • MgFe{sub 2}O{sub 4}-SiC attained the maximum absorbing value of 13.32 dB at 2.57 GHz, which reached extremely high RL value at low frequency range. • Fast decolorization and high TOC removal of azo dye Direct Black BN with complicated structure could occur with MgFe{sub 2}O{sub 4}-SiC under MW radiation. • MgFe{sub 2}O{sub 4}-SiC had better MW absorbing property and higher MW catalytic activity than MnFe{sub 2}O{sub 4}-SiC under the same condition. • MgFe{sub 2}O{sub 4}-SiC was of practical use in the wastewater treatment. - Abstract: A novel microwave (MW) catalyst, MgFe{sub 2}O{sub 4} loaded on SiC (MgFe{sub 2}O{sub 4}-SiC), was successfully synthesized by sol-gel method, and pure MgFe{sub 2}O{sub 4} was used as reference. The MgFe{sub 2}O{sub 4} and MgFe{sub 2}O{sub 4}-SiC catalysts were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), N{sub 2} adsorption analyzer (BET specific surface area), X-ray photoelectron spectroscopy (XPS). The electromagnetic parameters of the prepared catalysts were measured by vector network analyzer. The reflection loss (RL) based on the electromagnetic parameters calculated in Matlab showed MgFe{sub 2}O{sub 4}-SiC attained the maximum absorbing value of 13.32 dB at 2.57 GHz, which reached extremely high RL value at low frequency range, revealing the excellent MW absorption property of MgFe{sub 2}O{sub 4}-SiC. MW-induced degradation of Direct Black BN (DB BN) over as-synthesized MgFe{sub 2}O{sub 4}-SiC indicated that degradation efficiency of DB BN (20 mg L{sup −1}) in 5 min reached 96.5%, the corresponding TOC removal was 65%, and the toxicity of DB BN after degradation by MgFe{sub 2}O{sub 4}-SiC obviously decreased. The good stability and applicability of MgFe{sub 2}O{sub 4}-SiC on the degradation process were also discovered. Moreover, the ionic chromatogram during degradation

Mg-Fe Isotope Systems of Mantle Xenoliths: Constrains on the Evolution of Siberian Craton

Science.gov (United States)

An, Y.; Kiseeva, E. S.; Sobolev, N. V.; Zhang, Z.

2017-12-01

Mantle xenoliths bring to the surface a variety of lithologies (dunites, lherzolites, harzburgites, wehrlites, eclogites, pyroxenites, and websterites) and represent snapshots of the geochemical processes that occur deep within the Earth. Recent improvements in the precision of the MC-ICP-MS measurements have allowed us to expand the amount of data on Mg and Fe isotopes for mantle-derived samples. For instance, to constrain the isotopic composition of the Earth based on the study of spinel and garnet peridotites (An et al., 2017; Teng et al., 2010), to trace the origin and to investigate the isotopic fractionation mechanism during metamorphic process using cratonic or orogenic eclogites (Li et al., 2011; Wang et al., 2012) and to reveal the metasomatism-induced mantle heterogeneity by pyroxenites (Hu et al., 2016). Numerous multi-stage modification events and mantle layering are detected in the subcontinental lithospheric mantle under the Siberian craton (Ashchepkov et al., 2008a; Sobolev et al., 1975, etc). Combined analyses of Mg and Fe isotopic systems could provide new constraints on the formation and evolution of the ancient cratonic mantle. In order to better constrain the magnitude and mechanism of inter-mineral Mg and Fe isotopic fractionations at high temperatures, systematic studies of mantle xenoliths are needed. For example, theoretical calculations and natural samples measurements have shown that large equilibrium Mg isotope fractionations controlled by the difference in coordination number of Mg among minerals could exist (Huang et al., 2013; Li et al., 2011). Thus, the Mg isotope geothermometer could help us trace the evolution history of ancient cratons. In this study we present Mg and Fe isotopic data for whole rocks and separated minerals (clinopyroxene (cpx) and garnet (grt)) from different types of mantle xenoliths (garnet pyroxenites, eclogites, grospydites and garnet peridotites) from a number of kimberlite pipes in Siberian craton (Udachnaya

Synthesis, characterization and adsorptive performance of MgFe2O4 nanospheres for SO2 removal.

Science.gov (United States)

Zhao, Ling; Li, Xinyong; Zhao, Qidong; Qu, Zhenping; Yuan, Deling; Liu, Shaomin; Hu, Xijun; Chen, Guohua

2010-12-15

A type of uniform Mg ferrite nanospheres with excellent SO(2) adsorption capacity could be selectively synthesized via a facile solvothermal method. The size of the MgFe(2)O(4) nanospheres was controlled to be 300-400 nm in diameter. The structural, textural, and surface properties of the adsorbent have been fully characterized by a variety of techniques (Brunauer-Emmett-Teller, BET; X-ray diffraction analysis, XRD; scanning electron microscopy, SEM; and energy-dispersive X-ray spectroscopy, EDS). The valence states and the surface chemical compositions of MgFe(2)O(4) nanospheres were further identified by X-ray photoelectron spectroscopy (XPS). The behaviors of SO(2) oxidative adsorption on MgFe(2)O(4) nanospheres were studied using Fourier transform infrared spectroscopy (FTIR). Both the sulfite and sulfate species could be formed on the surface of MgFe(2)O(4). The adsorption equilibrium isotherm of SO(2) was analyzed using a volumetric method at 298 K and 473 K. The results indicate that MgFe(2)O(4) nanospheres possess a good potential as the solid-state SO(2) adsorbent for applications in hot fuel gas desulfurization. Copyright © 2010 Elsevier B.V. All rights reserved.

Single Low Dose Primaquine (0.25 mg/kg Does Not Cause Clinically Significant Haemolysis in G6PD Deficient Subjects.

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Germana Bancone

.7% were greater than in G6PD normal subjects (0.3%, -0.8 and -1.7% but were clinically insignificant. Fractional drops in haemoglobin concentration larger than 25% following single dose primaquine were observed in 1.8% of the population but were asymptomatic.The single low dose (0.25mg/kg of primaquine is clinically well tolerated and can be used safely without prior G6PD testing in populations with high prevalence of G6PD deficiency. The present evidence supports a broader use of low dose primaquine without G6PD testing for the treatment and elimination of falciparum malaria.ClinicalTrials.gov NCT01872702.

Effect of Mn and Fe on the Formation of Fe- and Mn-Rich Intermetallics in Al-5Mg-Mn Alloys Solidified Under Near-Rapid Cooling.

Science.gov (United States)

Liu, Yulin; Huang, Gaoren; Sun, Yimeng; Zhang, Li; Huang, Zhenwei; Wang, Jijie; Liu, Chunzhong

2016-01-29

Mn was an important alloying element used in Al-Mg-Mn alloys. However, it had to be limited to a low level (Al-5Mg-Mn alloy with low Fe content (Al₆(Fe,Mn) was small in size and amount. With increasing Mn content, intermetallic Al₆(Fe,Mn) increased, but in limited amount. In high-Fe-containing Al-5Mg-Mn alloys (0.5 wt % Fe), intermetallic Al₆(Fe,Mn) became the dominant phase, even in the alloy with low Mn content (0.39 wt %). Cooling rate played a critical role in the refinement of the intermetallics. Under near-rapid cooling, intermetallic Al₆(Fe,Mn) was extremely refined. Even in the high Mn and/or high-Fe-containing alloys, it still demonstrated fine Chinese script structures. However, once the alloy composition passed beyond the eutectic point, the primary intermetallic Al₆(Fe,Mn) phase displayed extremely coarse platelet-like morphology. Increasing the content of Fe caused intermetallic Al₆(Fe,Mn) to become the primary phase at a lower Mn content.

Mg-Fe-mixed oxides derived from layered double hydroxides: A study of the surface properties

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Marinković-Nedučin Radmila P.

2011-01-01

Full Text Available The influence of surface properties on the selectivity of the synthesized catalysts was studied, considering that their selectivity towards particular hydrocarbons is crucial for their overall activity in the chosen Fischer- -Tropsch reaction. Magnesium- and iron-containing layered double hydroxides (LDH, with the general formula: [Mg1-xFex(OH2](CO3x/2?mH2O, x = = n(Fe/(n(Mg+n(Fe, synthesized with different Mg/Fe ratio and their thermally derived mixed oxides were investigated. Magnesium was chosen because of its basic properties, whereas iron was selected due to its well-known high Fischer-Tropsch activity, redox properties and the ability to form specific active sites in the layered LDH structure required for catalytic application. The thermally less stable multiphase system (synthesized outside the optimal single LDH phase range with additional Fe-phase, having a lower content of surface acid and base active sites, a lower surface area and smaller fraction of smaller mesopores, showed higher selectivity in the Fischer-Tropsch reaction. The results of this study imply that the metastability of derived multiphase oxides structure has a greater influence on the formation of specific catalyst surface sites than other investigated surface properties.

Reduction of CaO and MgO Slag Components by Al in Liquid Fe

Science.gov (United States)

Mu, Haoyuan; Zhang, Tongsheng; Fruehan, Richard J.; Webler, Bryan A.

2018-05-01

This study documents laboratory-scale observations of reactions between Fe-Al alloys (0.1 to 2 wt pct Al) with slags and refractories. Al in steels is known to reduce oxide components in slag and refractory. With continued development of Al-containing Advanced High-Strength Steel (AHSS) grade, the effects of higher Al must be examined because reduction of components such as CaO and MgO could lead to uncontrolled modification of non-metallic inclusions. This may lead to castability or in-service performance problems. In this work, Fe-Al alloys and CaO-MgO-Al2O3 slags were melted in an MgO crucible and samples were taken at various times up to 60 minutes. Inclusions from these samples were characterized using an automated scanning electron microscope equipped with energy dispersive x-ray analysis (SEM/EDS). Initially Al2O3 inclusions were modified to MgAl2O4, then MgO, then MgO + CaO-Al2O3-MgO liquid inclusions. Modification of the inclusions was faster at higher Al levels. Very little Ca modification was observed except at 2 wt pct Al level. The thermodynamic feasibility of inclusion modification and some of the mass transfer considerations that may have led to the differences in the Mg and Ca modification behavior were discussed.

Very low sound velocities in iron-rich (Mg,Fe)O: Implications for the core-mantle boundary region

International Nuclear Information System (INIS)

Wicks, J.K.; Jackson, J.M.; Sturhahn, W.

2010-01-01

The sound velocities of (Mg .16 Fe .84 )O have been measured to 121 GPa at ambient temperature using nuclear resonant inelastic x-ray scattering. The effect of electronic environment of the iron sites on the sound velocities were tracked in situ using synchrotron Moessbauer spectroscopy. We found the sound velocities of (Mg .16 Fe .84 )O to be much lower than those in other presumed mantle phases at similar conditions, most notably at very high pressures. Conservative estimates of the effect of temperature and dilution on aggregate sound velocities show that only a small amount of iron-rich (Mg,Fe)O can greatly reduce the average sound velocity of an assemblage. We propose that iron-rich (Mg,Fe)O be a source of ultra-low velocity zones. Other properties of this phase, such as enhanced density and dynamic stability, strongly support the presence of iron-rich (Mg,Fe)O in localized patches above the core-mantle boundary.

The A1 to L10 transformation in FePt films with ternary alloying additions of Mg, V, Mn, and B

International Nuclear Information System (INIS)

Wang, B.; Barmak, K.; Klemmer, T. J.

2011-01-01

The impact of ternary additions of Mg, V, Mn, and B on the A1 [face centered cubic (fcc)] to L1 0 phase transformation has been studied. The films were cosputter deposited from elemental targets at room temperature and annealed after deposition. The films had Mg additions in the range ∼0-2.6 at.%, V additions in the range 0.7-12.2 at.%, Mn additions in the range 2.2-16.3 at.%, and B additions in the range 1.2-12.9 at.%. For all four ternary alloy systems, annealing resulted in the formation of no other phases than the L1 0 phase. Ternary additions of C than the binary FePt films with the same Pt content.

Effects of Be, Sr, Fe and Mg interactions on the microstructure and mechanical properties of aluminum based aeronautical alloys

Science.gov (United States)

Ibrahim, Mohamed Fawzy

dissolution, thinning, necking and fragmentation of these platelets upon increasing the solutionizing time. The pi-phase was observed to dissolve and/or transform into a cluster of very fine beta-phase platelets. In the as-cast conditions, increasing the Mg content leads to increased transformation of beta-phase platelets into Chinese-script pi-phase, regardless of the Fe content. This, in turn, decreases the harmful effect of the beta-phase. Increasing the solutionizing time leads to a decomposition of the pi-phase to the beta-phase, fragmentation of the beta-phase and spheroidization of both the eutectic Si and the pi-phase particles, thus improving alloy tensile properties. Two mechanisms of Mg2Si precipitate coarsening were observed to occur: (1) Ostwald ripening in the solution heat-treated samples and (2) clustering. Coarsening increases with increased solution heat treatment time, increased aging time, as well as with greater Mg contents. Increased Fe levels decrease the alloy quality index (Q) values, whereas adding Mg increases them. Introducing Be, in spite of it being a toxic material, Sr, or both, simultaneously improves the alloy quality index values, regardless of solutionizing time or Fe and Mg levels. Quality index values increase with solution heat treatment time from 5 to 12 hours. Higher Mg contents lead to an increase in alloy ductility, ultimate tensile strength (UTS) and yield strength (YS), while higher Fe levels can drastically decrease these properties. For the same levels of Fe and/or Mg, Be and Sr have significant effects in improving alloy mechanical properties; these effects can be readily observed in low levels of Fe and high Mg contents. Beryllium addition is beneficial in the case of high Fe contents as it lowers the harmful effects of Fe-phases in Al-Si alloys. In the case of high Fe contents, it seems that the addition of 500 ppm of Be is not sufficient for all interactions with other alloying elements. During the melting process the

The concentration of Fe and Zn in food-stuff of agriculture, husbandry and fishery determined by k0-INAA

International Nuclear Information System (INIS)

Th Rina Mulyaningsih

2009-01-01

Deficiency of iron (Fe) and zinc (Zn) micronutrient was suffered by population Therefore the determination of Fe and Zn in agriculture, husbandry, and fishery were carried out. The objective of this research is to estimate Fe and Zn intake through consumed food-stuff. Sampling was done in Pasar Serpong, while Fe and Zn was determined by k 0 - instrumental neutron activation analysis (k 0 -INAA). The result of analysis indicated that concentration of Fe and Zn in beef, goat and goat liver were >150 µg/g, in chicken flesh were around 30 µg/g. This food-stuff is good as source intake of Fe and Zn, due to level of consumption was low i.e. 0.001 - 0.018 kg/day, so its intake was lower enough i.e. 0.1 - 0.5 mg/day. The concentration of Fe and Zn in rice were < 50 µg/g, but because of consume level is high enough 0.3 kg/day, so Fe and Zn intake from rice is high enough. Zn and Fe content in spinach is 119 µg/g and 248 µg/g, Zn and Fe content in Kangkung is 54.84 µg/g, and 337 µg/g, and with consume level of ~0.015 kg/day it is good source of Zn arid Fe intake i.e 0.8 - 3.5 mg/day. The concentration of Zn in egg was 39.0184 µg/g and Fe was 74.45 µg/g because of level consume is higher than chicken flesh, so Zn and Fe intake from egg is higher than from chicken flesh, i.e. 0.85 - 1.64 mg/day. By knowing Fe and Zn concentration in foodstuff, supported with its consume level, Zn and Fe intake every day can be estimated. (author)

Impact of interface manipulation of oxide on electrical transport properties and low-frequency noise in MgO/NiFe/MgO heterojunctions

OpenAIRE

Jian-wei Li; Chong-jun Zhao; Chun Feng; Zhongfu Zhou; Guang-hua Yu

2015-01-01

Low-frequency noise and magnetoresistance in sputtered-deposited Ta(5 nm)/MgO (3 nm)/NiFe(10 nm)/MgO(3 nm)/Ta(3 nm) films have been measured as a function of different annealing times at 400°C. These measurements did not change synchronously with annealing time. A significant increase in magnetoresistance is observed for short annealing times (of the order of minutes) and is correlated with a relatively small reduction in 1/f noise. In contrast, a significant reduction in 1/f noise is observe...

Electrical and magnetic properties of FM/MgO/FM (FM  =  Co90Fe10, Fe20Ni80) heterostructures

International Nuclear Information System (INIS)

Avilés-Félix, L; González, J; Gómez, J E; Sirena, M

2016-01-01

In this paper we present the development and characterization of FM/MgO/FM (FM  =  Co 90 Fe 10 , Fe 20 Ni 80 ) heterostructures. The magnetic order of the structures, magnetic anisotropy and interlayer exchange coupling were characterized by magnetization measurements. The influence of the substrate temperature during growth on the magnetic properties and topographical features of the bottom electrode was also explored. Higher values of the coercive field were achieved increasing the substrate temperature during deposition of the bottom electrode. Patterned magnetic tunnel junctions were grown on Si(1 0 0) and MgO(1 0 0). The junctions consist of square pillars with different areas (1600, 625, 100 and 25 μ m 2 ) fabricated by optical lithography. I ( V ) curves obtained with conducting atomic force microscopy of the patterned junctions were performed at room temperature in order to explore the reproducibility of the transport properties of the insulating barrier. The results show a more insulating behavior of the junctions grown on Si(1 0 0), with very good control and a high reproducibility of the transport properties of the MgO insulating barrier. (paper)

Annealing effect on magnetic property and recording performance of [FePt/MgO]n perpendicular magnetic recording media

International Nuclear Information System (INIS)

Suzuki, Takao; Zhang, Zhengang; Singh, Amarendra K.; Yin, Jinhua; Perumal, A.; Osawa, Hiroshi

2005-01-01

Granular-type FePt perpendicular magnetic recording media with (001)-texture, obtained by annealing FePt/MgO multilayer films, are fabricated onto 2.5-in glass discs. For the sake of spin-stand testing, the coercivity of FePt films is carefully modulated by controlling the annealing conditions. With annealing, exchange coupling between FePt grains is decreased, indicated by the reductions in α value and activation volume. FePt ordering process is dependent on initial FePt/MgO multilayer structures, which governs the optimum annealing condition regarding coercivities and α(=4π(dM/dH)H=Hc). The SNR ratio exhibits a sensitive dependence on initial FePt/MgO multilayer structures as well as annealing conditions

Cr(VI) retention and transport through Fe(III)-coated natural zeolite

Energy Technology Data Exchange (ETDEWEB)

Du, Gaoxiang [School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Li, Zhaohui, E-mail: li@uwp.edu [School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Geosciences Department, University of Wisconsin-Parkside, Kenosha, WI 53144 (United States); Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Liao, Libing [School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Hanson, Renee; Leick, Samantha; Hoeppner, Nicole [Geosciences Department, University of Wisconsin-Parkside, Kenosha, WI 53144 (United States); Jiang, Wei-Teh [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China)

2012-06-30

Graphical abstract: Breakthrough curves of Cr(VI) from columns packed with raw zeolite (a) and Fe(III)-zeolite (b). The solid line in (b) is the HYDRUS-1D fit to the observed data with adsorption term only, while the dashed line in (b) includes a reduction term in the HYDRUS-1D fit. Highlights: Black-Right-Pointing-Pointer Zeolite modified with Fe(III) could be used for adsorption and retention of Cr(VI). Black-Right-Pointing-Pointer The Fe present on zeolite was in an amorphous Fe(OH){sub 3} form. Black-Right-Pointing-Pointer A Cr(VI) adsorption capacity of 82 mg/kg was found on Fe(III)-zeolite. Black-Right-Pointing-Pointer A Cr(VI) retardation factor of 3 or 5 was determined from column and batch studies. - Abstract: Cr(VI) is a group A chemical based on the weight of evidence of carcinogenicity. Its transport and retention in soils and groundwater have been studied extensively. Zeolite is a major component in deposits originated from volcanic ash and tuff after alteration. In this study, zeolite aggregates with the particle size of 1.4-2.4 mm were preloaded with Fe(III). The influence of present Fe(III) on Cr(VI) retention by and transport through zeolite was studied under batch and column experiments. The added Fe(III) resulted in an enhanced Cr(VI) retention by the zeolite with a capacity of 82 mg/kg. The Cr(VI) adsorption on Fe(III)-zeolite followed a pseudo-second order kinetically and the Freundlich adsorption isotherm thermodynamically. Fitting the column experimental data to HYDRUS-1D resulted in a retardation factor of 3 in comparison to 5 calculated from batch tests at an initial Cr(VI) concentration of 3 mg/L. The results from this study showed that enhanced adsorption and retention of Cr(VI) may happen in soils derived from volcanic ash and tuff that contains significant amounts of zeolite with extensive Fe(III) coating.

A simple route to improve rate performance of LiFePO4/reduced graphene oxide composite cathode by adding Mg2+ via mechanical mixing

Science.gov (United States)

Huang, Yuan; Liu, Hao; Gong, Li; Hou, Yanglong; Li, Quan

2017-04-01

Introducing Mg2+ to LiFePO4 and reduced graphene oxide composite via mechanical mixing and annealing leads to largely improved rate performance of the cathode (e.g. ∼78 mA h g-1 at 20 C for LiFePO4 and reduced graphene oxide composite with Mg2+ introduction vs. ∼37 mA h g-1 at 20 C for LiFePO4 and reduced graphene oxide composite). X-ray photoelectron spectroscopy unravels that the enhanced reduction of Fe2+ to Fe0 occurs in the simultaneous presence of Mg2+ and reduced graphene oxide, which is beneficial for the rate capability of cathode. The simple fabrication process provides a simple and effective means to improve the rate performance of the LiFePO4 and reduced graphene oxide composite cathode.

Diagnose nutricional de cafeeiros da região do Alto Jequitinhonha (MG: normas dris e faixas críticas de nutrientes Nutritional diagnosis of coffee plantations in the Upper Jequitinhonha Valley, Minas Gerais State, Brazil: dris norms and critical nutrient ranges

Directory of Open Access Journals (Sweden)

Múcio Mágno de Melo Farnezi

2009-08-01

Full Text Available As normas do Sistema Integrado de Diagnose e Recomendação (DRIS ainda não foram estabelecidas para a cultura do café do Alto Jequitinhonha, MG, o que impede que o DRIS seja aplicado nos cafeeiros da região. A diagnose foliar, mediante o uso do DRIS e de faixas críticas de referência, destaca-se entre as ferramentas potenciais que permitem usar eficientemente os fertilizantes. Desse modo, este trabalho objetiva estabelecer as normas DRIS, bem como estimar os valores das faixas críticas dos nutrientes de referência para a diagnose nutricional de cafeeiros da região do Alto Jequitinhonha, por meio do DRIS. Determinaram-se os teores foliares de N, P, K, Ca, Mg, S, B, Cu, Fe, Mn e Zn em 52 lavouras cafeeiras, em duas safras (2005 e 2006. Foram selecionadas, para estabelecer as normas DRIS, 23 lavouras em cada safra com produtividade maior e igual a 30 sacas de grãos de café por hectare. As faixas críticas obtidas do DRIS, determinando-se a frequência com que o teor de cada nutriente das lavouras nas duas safras foi deficiente, adequado ou excessivo em relação aos padrões mencionados e teores considerados adequados pela literatura. As normas DRIS foram estabelecidas para cafeeiros da região do Alto Jequitinhonha e utilizadas para propor faixas críticas adequadas. Para isso, foram estabelecidos os valores para N (2,25-2,79 dag kg-1, P (0,18-0,22 dag kg-1, K (1,72-2,10 dag kg-1, Ca (1,26-1,51 dag kg-1, Mg (0,29-0,35 dag kg-1, S (0,13-0,32 dag kg-1, B (83,8-96,3 mg kg-1, Cu (5,7-9,3 mg kg-1, Fe (67,5-116,2 mg kg-1, Mn (219-422 mg kg-1 e Zn (17,4-30,0 mg kg-1, e faixas críticas adequadas para diagnose nutricional de cafeeiros da região do Alto Jequitinhonha, no Estado de Minas Gerais. Os cafezais da região em desequilíbrio apresentaram deficiência em P, K, S, B, Cu, Mn e Zn e excesso de Ca, Mg e Fe.In the Diagnosis and Recommendation Integrated System (DRIS, norms for coffee in the Upper Jequitinhonha Valley, Minas Gerais, Brazil

Incorporation of Mg and Ca into nanostructured Fe2O3 improves Fe solubility in dilute acid and sensory characteristics in foods.

Science.gov (United States)

Hilty, Florentine M; Knijnenburg, Jesper T N; Teleki, Alexandra; Krumeich, Frank; Hurrell, Richard F; Pratsinis, Sotiris E; Zimmermann, Michael B

2011-01-01

Iron deficiency is one of the most common micronutrient deficiencies worldwide. Food fortification can be an effective and sustainable strategy to reduce Fe deficiency but selection of iron fortificants remains a challenge. Water-soluble compounds, for example, FeSO(4), usually demonstrate high bioavailability but they often cause unacceptable sensory changes in foods. On the other hand, poorly acid-soluble Fe compounds, for example FePO(4), may cause fewer adverse sensory changes in foods but are usually not well bioavailable since they need to be dissolved in the stomach prior to absorption. The solubility and the bioavailability of poorly acid-soluble Fe compounds can be improved by decreasing their primary particle size and thereby increasing their specific surface area. Here, Fe oxide-based nanostructured compounds with added Mg or Ca were produced by scalable flame aerosol technology. The compounds were characterized by nitrogen adsorption, X-ray diffraction, transmission electron microscopy, and Fe solubility in dilute acid. Sensory properties of the Fe-based compounds were tested in 2 highly reactive, polyphenol-rich food matrices: chocolate milk and fruit yoghurt. The Fe solubility of nanostructured Fe(2)O(3) doped with Mg or Ca was higher than that of pure Fe(2)O(3). Since good solubility in dilute acid was obtained despite the inhomogeneity of the powders, inexpensive precursors, for example Fe- and Ca-nitrates, can be used for their manufacture. Adding Mg or Ca lightened powder color, while sensory changes when added to foods were less pronounced than for FeSO(4). The combination of high Fe solubility and low reactivity in foods makes these flame-made nanostructured compounds promising for food fortification. Practical Application: The nanostructured iron-containing compounds presented here may prove useful for iron fortification of certain foods; they are highly soluble in dilute acid and likely to be well absorbed in the gut but cause less severe

Novel ZnO/MgO/Fe2O3 composite optomagnetic nanoparticles

International Nuclear Information System (INIS)

Kamińska, I; Sikora, B; Fronc, K; Dziawa, P; Sobczak, K; Minikayev, R; Paszkowicz, W; Elbaum, D

2013-01-01

A facile sol–gel synthesis of novel ZnO/MgO/Fe 2 O 3 nanoparticles (NPs) is reported and their performance is compared to that of ZnO/MgO. Powder x-ray diffraction (XRD) patterns reveal the crystal structure of the prepared samples. The average particle size of the sample was found to be 4.8 nm. The optical properties were determined by UV–vis absorption and fluorescence measurements. The NPs are stable in biologically relevant solutions (phosphate buffered saline (PBS), 20 mM, pH = 7.0) contrary to ZnO/MgO NPs which degrade in the presence of inorganic phosphate. Superparamagnetic properties were determined with a superconducting quantum interference device (SQUID). Biocompatible and stable in PBS ZnO/MgO/Fe 2 O 3 core/shell composite nanocrystals show luminescent and magnetic properties confined to a single NP at room temperature (19–24 ° C), which may render the material to be potentially useful for biomedical applications. (paper)

Co-intercalation of Mg(2+) and Na(+) in Na(0.69)Fe2(CN)6 as a High-Voltage Cathode for Magnesium Batteries.

Science.gov (United States)

Kim, Dong-Min; Kim, Youngjin; Arumugam, Durairaj; Woo, Sang Won; Jo, Yong Nam; Park, Min-Sik; Kim, Young-Jun; Choi, Nam-Soon; Lee, Kyu Tae

2016-04-06

Thanks to the advantages of low cost and good safety, magnesium metal batteries get the limelight as substituent for lithium ion batteries. However, the energy density of state-of-the-art magnesium batteries is not high enough because of their low operating potential; thus, it is necessary to improve the energy density by developing new high-voltage cathode materials. In this study, nanosized Berlin green Fe2(CN)6 and Prussian blue Na(0.69)Fe2(CN)6 are compared as high-voltage cathode materials for magnesium batteries. Interestingly, while Mg(2+) ions cannot be intercalated in Fe2(CN)6, Na(0.69)Fe2(CN)6 shows reversible intercalation and deintercalation of Mg(2+) ions, although they have the same crystal structure except for the presence of Na(+) ions. This phenomenon is attributed to the fact that Mg(2+) ions are more stable in Na(+)-containing Na(0.69)Fe2(CN)6 than in Na(+)-free Fe2(CN)6, indicating Na(+) ions in Na(0.69)Fe2(CN)6 plays a crucial role in stabilizing Mg(2+) ions. Na(0.69)Fe2(CN)6 delivers reversible capacity of approximately 70 mA h g(-1) at 3.0 V vs Mg/Mg(2+) and shows stable cycle performance over 35 cycles. Therefore, Prussian blue analogues are promising structures for high-voltage cathode materials in Mg batteries. Furthermore, this co-intercalation effect suggests new avenues for the development of cathode materials in hybrid magnesium batteries that use both Mg(2+) and Na(+) ions as charge carriers.

A comparative study of metabolism and concentration factors of Fe, Cu, Zn, Mn, Co and Mg in Carcinus maenas and Cancer irroratus ovaries during ovogenesis

International Nuclear Information System (INIS)

Martin, J.-L.M.

1975-01-01

Fe, Cu, Zn, Mn, Co, and Mg were analysed in the ovary of Carcinus maenas and Cancer irroratus during ovogenesis. In both ovaries, the relatives rates, expressed as parts per millions as a ratio of wet and dry weight, are the following: Mg>Zn>Fe>Cu>Mn>Co, while in the hemolymph of Cancer irroratus these relative rates are the following: Mg>Cu>Zn>Fe>Mn>Co. Compared to concentrations of these metals in sea water, Mg expected, all metals in the ovary of Cancer irroratus have a concentration factor upper than 1. Compared to the concentration of metals in the hemolymph is, for Fe, Mn, and Co, the concentration factor upper than 1, and for Cu, Zn and Mg, the concentration factor lower than 1. A study of correlations was done between the concentrations of metals considered in pairs, and between the concentrations of metals and the parameters: water content and gonad index [fr

Compositional and structural variabilities of Mg-rich iron oxide spinels from tuffite

Directory of Open Access Journals (Sweden)

W. N. Mussel

1999-12-01

Full Text Available Maghemite (γFe2O3 from tuffite is exceptionally rich in Mg, relatively to most of those reportedly found in other mafic lithosystems. To investigate in detail the compositional and structural variabilities of this natural magnetic iron oxide, sets of crystals were isolated from samples collected at different positions in a tuffite weathering mantle. These sets of crystal were individually powdered and studied by X-ray diffractometry, Mössbauer spectroscopy, magnetization measurements and chemical analysis. Lattice parameter of the cubic cell (a0 was found to vary from 0.834(1 to 0.8412(1 nm. Lower a0-values are characteristic of maghemite whereas higher ones are related to a magnetite precursor. FeO content ranges up to 17 mass % and spontaneous magnetization ranges from 8 to 32 J T-1 kg-1. Zero-field room temperature Mössbauer spectra are rather complex, indicating that the hyperfine field distributions due to Fe3+ and mixed valence Fe3+/2+ overlap. The structural variabilities of the (Mg, Ti-rich iron oxide spinels is essentially related to the range of chemical composition of its precursor (Mg, Ti-rich magnetite, and probably to the extent to which it has been oxidized during transformation in soil.

Gas response properties of citrate gel synthesized nanocrystalline MgFe{sub 2}O{sub 4}: Effect of sintering temperature

Energy Technology Data Exchange (ETDEWEB)

Patil, J.Y. [School of Physical Sciences, Solapur University Solapur-413255 (India); Mulla, I.S. [Emeritus Scientist (CSIR), Centre for Materials for Electronic Technology(C-MET) Pune-411 008 (India); Suryavanshi, S.S., E-mail: sssuryavanshi@rediffmail.com [School of Physical Sciences, Solapur University Solapur-413255 (India)

2013-02-15

Graphical abstract: Display Omitted Highlights: ► Synthesis of nanocrystalline MgFe{sub 2}O{sub 4} by economical citrate gel combustion method. ► Structural, morphological, and gas response properties of MgFe{sub 2}O{sub 4}. ► Enhancement in selectivity of MgFe{sub 2}O{sub 4} towards LPG with sintering temperature. ► Use of MgFe{sub 2}O{sub 4} to detect different gases at different operating temperatures. -- Abstract: Spinel type MgFe{sub 2}O{sub 4} material was synthesized by citrate gel combustion method. The effect of sintering temperature on structural, morphological, and gas response properties was studied. The powder X-ray diffraction pattern and transmission electron microscope study confirms nanocrystalline spinel structure of the synthesized powder. The material was tested for response properties to various reducing gases like liquid petroleum gas (LPG), acetone, ethanol, and ammonia. The results demonstrated n-type semiconducting behavior of MgFe{sub 2}O{sub 4} material. It was revealed that MgFe{sub 2}O{sub 4} sintered at 973 K was most sensitive to LPG at 648 K and to acetone at 498 K. However MgFe{sub 2}O{sub 4} sintered at 1173 K exhibited higher response and selectivity to LPG with marginal increase in the operating temperature. Furthermore, the sensor exhibited a fast response and a good recovery. It was observed that the particles size, porosity, and surface activity of the sensor material is affected by the sintering temperature.

Fe/Ni thin films temperature investigation with MgO and SiO2 interfaces by ferromagnetic resonance

International Nuclear Information System (INIS)

Zyubin, A; Orlova, A; Astashonok, A; Kupriyanova, G; Nevolin, V

2011-01-01

In this work the temperature study of magnetic – resonance properties of the structures such as Fe/MgO/Ni, Fe/SiO2/Ni differing thickness of spacer and of method of preparation was carried out by FMR. These systems are investigated to estimate their applicability in model creation experiments for a spintronics devices research [1–4]. The special attention was given to the temperature dependence research of three layer films linewidths. The out-of-plane temperature dependences of FMR signal position and line widths have been measured for Fe/Ni samples with MgO and Si/SiO2 interfaces in static position of 0 and 90 degrees rotation angle to the external static magnetic field. The extracted magnetic parameters such as linewidths and resonance field position were studied.

Sorption of chromium (VI) by Mg/Fe hydrotalcite type compunds

Energy Technology Data Exchange (ETDEWEB)

García-Sosa, I., E-mail: irma.garcia@inin.gob.mx; Cabral-Prieto, A., E-mail: agustin.cabral@inin.gob.mx [Instituto Nacional de Investigaciones Nucleares, Departamento de Química (Mexico); Nava, N., E-mail: tnava@imp.mx; Navarrete, J. [Instituto Mexicano del Petróleo (Mexico); Olguín, M. T., E-mail: teresa.olguin@inin.gob.mx [Instituto Nacional de Investigaciones Nucleares, Departamento de Química (Mexico); Escobar, Luis, E-mail: luis.escobar@inin.gob.mx [Instituto Nacional de Investigaciones Nucleares, Departamento de Física (Mexico); López-Castañares, R., E-mail: rlc@anuies.mx; Olea-Cardoso, O., E-mail: olc@anuies.mx [Universidad Autónoma del Edo. de México, Facultad de Química (Mexico)

2015-06-15

The synthesis by co-precipitation and characterization by X-ray diffraction, Raman and Mössbauer spectroscopies of Mg-Fe-hydrotalcite compounds, and their sorption capacities for Cr(VI) in aqueous media were carried out. The average sorption capacity of Cr(VI) for the non-thermal treated samples was of 6.2 mg/g. The ferrihydrite was omnipresent in all prepared hydrotalcite samples. A brief discussion is made on the role of both the hydrotalcite and ferrihydrite for removing such amount of Cr(VI)

The high-pressure electronic structure of magnesiowustite (Mg, Fe)O: applications to the physics and chemistry of the lower mantle

Science.gov (United States)

Sherman, David M.

1991-01-01

The electronic structure of magnesiowustite is investigated using self-consistent field X?? scattered wave (SCF-X??-SW) molecular orbital calculations on (FeO6)10- and (FeMg12O14)2- clusters. Calculated one-electron transition energies are used to interpret the optical spectrum of (Mg, Fe)O. The results are applied to the electrical and thermal conductivity of the lower mantle. This is especially true if Fe2+ adopts the low-spin configuration. The geophysically significant properties of (Fe, Mg)O probably result from defect Fe3+. -from Author

All-solid-state lithium batteries – The Mg2FeH6-electrode LiBH4-electrolyte system

DEFF Research Database (Denmark)

Huen, Priscilla; Ravnsbæk, Dorthe B.

2018-01-01

The complex hydride Mg2FeH6 is investigated as conversion type anode in a solid-state all-hydride Li-battery employing LiBH4 as solid-state electrolyte. In the solid-state battery, Mg2FeH6 exhibits improvements in the capacity retention and initial Coulombic efficiency of > 3 and > 2.5 times......, respectively, compared to the conventional liquid-electrolyte battery. Through investigations of the conversion reactions of Mg2FeH6, formation of MgH2 as intermediate in the conversion to Mg is discovered the first time. In addition, the effect of mixing procedure for the electrode-electrolyte composite...... on the battery performance is discussed....

Fabrication of Mg-X-O (X = Fe, Co, Ni, Cr, Mn, Ti, V, and Zn) barriers for magnetic tunnel junctions

Science.gov (United States)

Yakushiji, K.; Kitagawa, E.; Ochiai, T.; Kubota, H.; Shimomura, N.; Ito, J.; Yoda, H.; Yuasa, S.

2018-05-01

We fabricated magnetic tunnel junctions with a 3d-transition material(X)-doped MgO (Mg-X-O) barrier, and evaluated the effect of the doping on magnetoresistance (MR) and microstructure. Among the variations of X (X = Fe, Co, Ni, Cr, Mn, Ti, V, and Zn), X = Fe and Mn showed a high MR ratio of more than 100%, even at a low resistance-area product of 3 Ωμm2. The microstructure analysis revealed that (001) textured orientation formed for X = Fe and Mn despite substantial doping (about 10 at%). The elemental mappings indicated that Fe atoms in the Mg-Fe-O barrier were segregated at the interfaces, while Mn atoms were evenly involved in the Mg-Mn-O barrier. This suggests that MgO has high adaptability for Fe and Mn dopants in terms of high MR ratio.

Ultrafast demagnetization enhancement in CoFeB/MgO/CoFeB magnetic tunneling junction driven by spin tunneling current.

Science.gov (United States)

He, Wei; Zhu, Tao; Zhang, Xiang-Qun; Yang, Hai-Tao; Cheng, Zhao-Hua

2013-10-07

The laser-induced ultrafast demagnetization of CoFeB/MgO/CoFeB magnetic tunneling junction is exploited by time-resolved magneto-optical Kerr effect (TRMOKE) for both the parallel state (P state) and the antiparallel state (AP state) of the magnetizations between two magnetic layers. It was observed that the demagnetization time is shorter and the magnitude of demagnetization is larger in the AP state than those in the P state. These behaviors are attributed to the ultrafast spin transfer between two CoFeB layers via the tunneling of hot electrons through the MgO barrier. Our observation indicates that ultrafast demagnetization can be engineered by the hot electrons tunneling current. It opens the door to manipulate the ultrafast spin current in magnetic tunneling junctions.

Signatures in magnetites formed by (Ca,Mg,Fe)CO3 thermal decomposition: Terrestrial and extraterrestrial implications

Science.gov (United States)

Jimenez-Lopez, Concepcion; Rodriguez-Navarro, Carlos; Rodriguez-Navarro, Alejandro; Perez-Gonzalez, Teresa; Bazylinski, Dennis A.; Lauer, Howard V.; Romanek, Christopher S.

2012-06-01

It has never been demonstrated whether magnetite synthesized through the heat-dependent decomposition of carbonate precursors retains the chemical and structural features of the carbonates. In this study, synthetic (Ca,Mg,Fe)CO3 was thermally decomposed by heating from 25 to 700 °C under 1 atm CO2, and by in situ exposure under vacuum to the electron beam of a transmission electron microscope. In both cases, the decomposition of the carbonate was topotactic and resulted in porous pseudomorphs composed of oriented aggregates of magnetite nanocrystals. Both calcium and magnesium were incorporated into nanophase magnetite, forming (Ca,Mg)-magnetites and (Ca,Mg)-ferrites when these elements were present in the parent material, thus preserving the chemical signature of the precursor. These results show that magnetites synthesized in this way acquire a chemical and structural inheritance from their carbonate precursor that indicates how they were produced. These results are not only important in the determination of the origin of chemically-impure, oriented nanophase magnetite crystals in general, but they also provide important insights into the origin of the large, euhedral, chemically-pure, [111]-elongated magnetites found within Ca-, Mg- and Fe-rich carbonates of the Martian meteorite ALH84001. Based on our experimental results, the chemically-pure magnetites within ALH84001 cannot be genetically related to the Ca-, Mg- and Fe-rich carbonate matrix within which they are embedded, and an alternative explanation for their occurrence is warranted.

Inorganic synthesis of Fe-Ca-Mg carbonates at low temperature

NARCIS (Netherlands)

Romanek, Christopher S.; Jiménez-López, Concepción; Navarro, Alejandro Rodriguez; Sánchez-Román, Monica; Sahai, Nita; Coleman, Max

2009-01-01

A set of free-drift experiments was undertaken to synthesize carbonates of mixed cation content (Fe, Ca, Mg) from solution at 25 and 70 °C to better understand the relationship between the mineralogy and composition of these phases and the solutions from which they precipitate. Metastable solid

Reaction texture and Fe-Mg zoning in granulite garnet from ...

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

each spot using 15kV accelerating voltage, 15nA beam current, and ... We refer to this distribution coefficient as ... are almost flat except that there is a sudden drop ..... determinations in the system FeO-MgO-Al2O3-SiO2, and applications; J.

MgFe{sub 2}O{sub 4}/ZrO{sub 2} composite nanoparticles for hyperthermia applications

Energy Technology Data Exchange (ETDEWEB)

Rashid, Amin ur [Magnetism Laboratory, Department of Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan); Department of Applied Physical and Material Sciences, University of Swat, Khyber Pakhtunkhwa (Pakistan); Humayun, Asif [Magnetism Laboratory, Department of Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan); Manzoor, Sadia, E-mail: sadia_manzoor@comsats.edu.pk [Magnetism Laboratory, Department of Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan)

2017-04-15

MgFe{sub 2}O{sub 4}/ZrO{sub 2} composites containing ZrO{sub 2} in different weight percentages from 0% to 80% were prepared via the citrate gel technique as potential candidate materials for magnetic hyperthermia. The biocompatible ceramic ZrO{sub 2} was introduced to prevent MgFe{sub 2}O{sub 4} nanoparticles from aggregation and to reduce their dipolar interactions in order to enhance the specific absorption rate (SAR). Structural and magnetic properties of the samples were studied using powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and a vibrating sample magnetometer (VSM). Magnetically induced heating in radio frequency (RF) magnetic fields was observed in all samples. Most significantly, the sample with only 20 wt% MgFe{sub 2}O{sub 4} has been found to have a SAR that is larger than that of pure MgFe{sub 2}O{sub 4}. This is an important finding from the point of view of biomedical applications, because ZrO{sub 2} in known to have low toxicity and a higher biocompatibility as compared to ferrites. - Highlights: • MgFe{sub 2}O{sub 4} and ZrO{sub 2} composite nanoparticles with different weight percentages of ZrO{sub 2} were prepared via the citrate gel technique. • Significant variation in magnetic properties was observed with increasing the weight % of ZrO{sub 2}. • Magnetically induced heating was observed when the composites were subjected to RF magnetic field. • Most significantly, the sample 80 wt% ZrO{sub 2} has been found to have SAR that is larger than that of pure MgFe{sub 2}O{sub 4}. • The SAR was found to have a strong dependence on magnetic dipolar interactions.

The Pressure-Volume-Temperature Equation of State of Iron-Rich (Mg,Fe)O

Science.gov (United States)

Wicks, J. K.; Jackson, J. M.; Zhuravlev, K. K.; Prakapenka, V.

2012-12-01

Seismic observations near the base of the core-mantle boundary (CMB) have detected 5-20 km thick patches in which the seismic wave velocities are reduced by up to 30%. These ultra-low velocity zones (ULVZs) have been interpreted as aggregates of partially molten material (e.g. Williams and Garnero 1996, Hernlund and Jellinek, 2010) or as solid, iron-enriched residues (e.g. Knittle and Jeanloz, 1991; Mao et al., 2006; Wicks et al., 2010), typically based on proposed sources of velocity reduction. The stabilities of these structure types have been explored through dynamic models that have assembled a relationship between ULVZ stability and density (Hernlund and Tackley, 2007; Bower et al., 2010). Now, to constrain the chemistry of ULVZs, more information is needed on the relationship between density and sound velocity of candidate phases. Recently, we have shown that the characteristically low sound speeds of ULVZs can be produced by small amounts of iron-rich (Mg,Fe)O, which is likely to be found in iron-rich assemblages based on current partitioning studies (eg. Sakai et al., 2010; Tange et al., 2009). We determined the Debye velocity (VD) of (Mg.1657Fe.84)O using nuclear resonant inelastic x-ray scattering (NRIXS), and calculated the seismically relevant compressional (VP) and shear (VS) wave velocities up to 120 GPa using an equation of state of a similar composition (Wicks et al., 2010). These densities and sound velocities, in turn, are consistent with reasonable morphologies of modeled solid ULVZs (Bower et al., 2011). To increase the accuracy of density and sound velocity predictions, measurements must be made at elevated temperatures to correctly predict the properties of iron-rich (Mg,Fe)O at mantle conditions. In this study, we present the pressure-volume-temperature equation of state of (Mg.0657Fe.94)O measured up to pressures of 120 GPa and temperatures of 2000 K. Volume was measured with x-ray diffraction at beamline 13-ID-D of the Advanced Photon

Evaluation of Pb and Fe tenors present in the sediments nearby the activities of taking advantage of lead-acid batteries; Avaliacao dos teores de Pb e Fe presentes nos sedimentos proximos as atividades de reaproveitamento de baterias chumbo-acidas

Energy Technology Data Exchange (ETDEWEB)

Soares, Fernanda; Andrade, Crescencio; Monteiro, Carlos; Oliveira, Daniela; Valentim, Eliane, E-mail: candrade@cnen.gov.b, E-mail: valentim@cnen.gov.b [Centro Regional de Ciencias Nucleares (CRCN/NE-CNEN/PE), Recife, PE (Brazil)

2011-07-01

The region chosen for this study was the Municipality of Belo Jardim, Pernambuco State, Brazil, which is considered an important industrial complex of the production and repairing of lead-acid batteries. Sediment samples were collected near to the illegal smelting industries and analyzed by ionic exchange method using a alpha-beta proportional counter for determining the activity of Pb-210, radionuclide used as geochronological tool. The chemical elements Pb and Fe were determined by means of flame atomic absorption spectrometry. The obtained results indicated an expressive increasing of lead and iron concentrations in the last 20 years. The concentrations in the sampled profile varied from 318 to 15487 mg.kg-1 and from 19 to 1524 mg.kg-1 for Fe and Pb, respectively. (author)

Origin of interfacial perpendicular magnetic anisotropy in MgO/CoFe/metallic capping layer structures.

Science.gov (United States)

Peng, Shouzhong; Wang, Mengxing; Yang, Hongxin; Zeng, Lang; Nan, Jiang; Zhou, Jiaqi; Zhang, Youguang; Hallal, Ali; Chshiev, Mairbek; Wang, Kang L; Zhang, Qianfan; Zhao, Weisheng

2015-12-11

Spin-transfer-torque magnetic random access memory (STT-MRAM) attracts extensive attentions due to its non-volatility, high density and low power consumption. The core device in STT-MRAM is CoFeB/MgO-based magnetic tunnel junction (MTJ), which possesses a high tunnel magnetoresistance ratio as well as a large value of perpendicular magnetic anisotropy (PMA). It has been experimentally proven that a capping layer coating on CoFeB layer is essential to obtain a strong PMA. However, the physical mechanism of such effect remains unclear. In this paper, we investigate the origin of the PMA in MgO/CoFe/metallic capping layer structures by using a first-principles computation scheme. The trend of PMA variation with different capping materials agrees well with experimental results. We find that interfacial PMA in the three-layer structures comes from both the MgO/CoFe and CoFe/capping layer interfaces, which can be analyzed separately. Furthermore, the PMAs in the CoFe/capping layer interfaces are analyzed through resolving the magnetic anisotropy energy by layer and orbital. The variation of PMA with different capping materials is attributed to the different hybridizations of both d and p orbitals via spin-orbit coupling. This work can significantly benefit the research and development of nanoscale STT-MRAM.

Epitaxial growth and magnetic properties of Fe4-xMnxN thin films grown on MgO(0 0 1) substrates by molecular beam epitaxy

Science.gov (United States)

Anzai, Akihito; Takata, Fumiya; Gushi, Toshiki; Toko, Kaoru; Suemasu, Takashi

2018-05-01

Epitaxial Fe4-xMnxN (x = 0, 1, 2, 3, and 4) thin films were successfully grown on MgO(0 0 1) single-crystal substrates by molecular beam epitaxy, and their crystalline qualities and magnetic properties were investigated. It was found that the lattice constants of Fe4-xMnxN obtained from X-ray diffraction measurement increased with the Mn content. The ratio of the perpendicular lattice constant c to the in-plane lattice constant a of Fe4-xMnxN was found to be about 0.99 at x ⩾ 2. The magnetic properties evaluated using a vibrating sample magnetometer at room temperature revealed that all of the Fe4-xMnxN films exhibited ferromagnetic behavior regardless of the value of x. In addition, the saturation magnetization decreased non-linearly as the Mn content increased. Finally, FeMn3N and Mn4N exhibited perpendicular anisotropy and their uniaxial magnetic anisotropy energies were 2.2 × 105 and 7.5 × 105 erg/cm3, respectively.

Study of some Mg-based ferrites as humidity sensors

International Nuclear Information System (INIS)

Rezlescu, N; Rezlescu, E; Doroftei, C; Popa, P D

2005-01-01

The micostructure and humidity sensitivity of MgFe 2 O 4 + CaO, Mg 0.5 Cu 0.5 Fe 1.8 Ga 0.2 O 4 , Mg 0.5 Zn 0.5 Fe 2 O 4 + KCl and MgMn 0.2 Fe 1.8 O 4 ferrites were investigated. We have found that the humidity sensitivity largely depends on composition, crystallite size, surface area and porosity. The best results concerning humidity sensitivity were obtained for MgMn 0.2 Fe 1.8 O 4 ferrite

High-Pressure Study of Perovskites and Postperovskites in the (Mg,Fe)GeO ₃ System

Energy Technology Data Exchange (ETDEWEB)

Stan, Camelia V.; Dutta, Rajkrishna; Cava, Robert J.; Prakapenka, Vitali B.; Duffy, Thomas S. (Princeton); (UC)

2017-06-22

The effect of incorporation of Fe²⁺ on the perovskite (Pbnm) and postperovskite (Cmcm) structures was investigated in the (Mg,Fe)GeO₃ system at high pressures and temperatures using laser-heated diamond anvil cell and synchrotron X-ray diffraction. Samples with compositions of Mg# ≥ 48 were shown to transform to the perovskite (~30 GPa and ~1500 K) and postperovskite (>55 GPa, ~1600–1800 K) structures. Compositions with Mg# ≥ 78 formed single-phase perovskite and postperovskite, whereas those with Mg# < 78 showed evidence for partial decomposition. The incorporation of Fe into the perovskite structure causes a decrease in octahedral distortion as well as a modest decrease in bulk modulus (K₀) and a modest increase in zero-pressure volume (V₀). It also leads to a decrease in the perovskite-to-postperovskite phase transition pressure by ~9.5 GPa over compositions from Mg#78 to Mg#100.

Controls of Ca/Mg/Fe activity ratios in pore water chemistry models of the Callovian-Oxfordian clay formation

International Nuclear Information System (INIS)

Lerouge, C.; Grangeon, S.; Wille, G.; Flehoc, C.; Gailhanou, H.; Gaucher, E.C.; Tournassat, C.; Vinsot, A.; Made, B.; Altmann, S.

2013-01-01

In the pore water chemistry model of the Callovian-Oxfordian clay formation, the divalent cations Ca, Mg, and Fe are controlled by equilibrium reactions with pure carbonates: calcite for Ca, dolomite for Mg, and siderite for Fe. Results of a petrological study and computing of the Ca/Mg and Ca/Fe activity ratios based on natural pore water chemistry provide evidence that equilibrium with pure calcite and pure dolomite is a reasonable assumption for undisturbed pore waters; on the other hand, siderite cannot be considered at equilibrium with pore waters at the formation scale. (authors)

Controls of Ca/Mg/Fe activity ratios in pore water chemistry models of the Callovian-Oxfordian clay formation

Energy Technology Data Exchange (ETDEWEB)

Lerouge, C.; Grangeon, S.; Wille, G.; Flehoc, C.; Gailhanou, H.; Gaucher, E.C.; Tournassat, C. [BRGM av. Claude Guillemin BP6009 45060 Orleans cedex 2 (France); Vinsot, A. [ANDRA Meuse/Haute-Marne Underground research Laboratory (URL), RD 960, 55290 Bure (France); Made, B.; Altmann, S. [ANDRA - Parc de la Croix Blanche, 1-7 rue Jean Monnet, 92298 Chatenay-Malabry Cedex (France)

2013-07-01

In the pore water chemistry model of the Callovian-Oxfordian clay formation, the divalent cations Ca, Mg, and Fe are controlled by equilibrium reactions with pure carbonates: calcite for Ca, dolomite for Mg, and siderite for Fe. Results of a petrological study and computing of the Ca/Mg and Ca/Fe activity ratios based on natural pore water chemistry provide evidence that equilibrium with pure calcite and pure dolomite is a reasonable assumption for undisturbed pore waters; on the other hand, siderite cannot be considered at equilibrium with pore waters at the formation scale. (authors)

Potential Health Risk Assessment of Cr, Cu, Fe and Zn for Human Population via Consumption of Commercial Spices; a Case Study of Hamedan City, Iran

Directory of Open Access Journals (Sweden)

Sobhanardakani S.* PhD

2016-09-01

Full Text Available Abstract Aims: Spices are sources of many bioactive compounds that can improve the taste of food as well as affecting the digestion and metabolism. Along with that, they may also contain some substances as heavy metals, which have harmful effects on the body. The aim of present study was to assess the potential health risk of Cr, Cu, Fe and Zn contents of cardamom, curry powder and turmeric in Hamedan City, Iran. Instrument & Methods: 18 industrially packaged and weighted spice samples (cardamom, curry powder and turmeric belonging to 6 famous brands were bought from different supermarkets of Hamedan City, Iran, in 2015. The human health risks posed by chronic exposure to the heavy metals were assessed by computing the average daily intake of metal. The health risk index (HRI for the local population through the consumption of spice was assessed using DIM/RfD formula. Data were analyzed using ANOVA, DMS post-hoc, Tukey HSD and Pearson's correlation coefficient tests. Findings: Cr was detected in spice samples in 0.08-1.67mg/kg, Cu 0.05-1.28mg/kg, Fe 1.04-6.89mg/kg and Zn 0.40-2.25mg/kg. The mean concentration of Cu, Fe and Zn were lower than MPL. The DIM values for the examined spice samples were below the recommended values. Conclusion: The levels of Cr, Cu, Fe and Zn are less than the MPL in cardamom, curry powder and turmeric in Hamedan City, Iran.

Thermal equation of state of (Mg 0.9Fe 0.1) 2SiO 4 olivine

Science.gov (United States)

Liu, Wei; Li, Baosheng

2006-08-01

In situ synchrotron X-ray diffraction measurements have been carried out on San Carlos olivine (Mg 0.9Fe 0.1) 2SiO 4 up to 8 GPa and 1073 K. Data analysis using the high-temperature Birch-Murnaghan (HTBM) equation of state (EoS) yields the temperature derivative of the bulk modulus (∂ KT/∂ T) P = -0.019 ± 0.002 GPa K -1. The thermal pressure (TH) approach gives αKT = 4.08 ± 0.10 × 10 -3 GPa K -1, from which (∂ KT/∂ T) P = -0.019 ± 0.001 GPa K -1 is derived. Fitting the present data to the Mie-Grüneisen-Debye (MGD) formalism, the Grüneisen parameter at ambient conditions γ0 is constrained to be 1.14 ± 0.02 with fixed volume dependence q = 1. Combining the present data with previous results on iron-bearing olivine and fitting to MGD EoS, we obtain γ0 = 1.11 ± 0.01 and q = 0.54 ± 0.36. In this study the thermoelastic parameters obtained from various approaches are in good agreement with one another and previous results.

Synthesis, mechanical properties and corrosion behavior of powder metallurgy processed Fe/Mg2Si composites for biodegradable implant applications.

Science.gov (United States)

Sikora-Jasinska, M; Paternoster, C; Mostaed, E; Tolouei, R; Casati, R; Vedani, M; Mantovani, D

2017-12-01

Recently, Fe and Fe-based alloys have shown their potential as degradable materials for biomedical applications. Nevertheless, the slow corrosion rate limits their performance in certain situations. The shift to iron matrix composites represents a possible approach, not only to improve the mechanical properties, but also to accelerate and tune the corrosion rate in a physiological environment. In this work, Fe-based composites reinforced by Mg 2 Si particles were proposed. The initial powders were prepared by different combinations of mixing and milling processes, and finally consolidated by hot rolling. The influence of the microstructure on mechanical properties and corrosion behavior of Fe/Mg 2 Si was investigated. Scanning electron microscopy and X-ray diffraction were used for the assessment of the composite structure. Tensile and hardness tests were performed to characterize the mechanical properties. Potentiodynamic and static corrosion tests were carried out to investigate the corrosion behavior in a pseudo-physiological environment. Samples with smaller Mg 2 Si particles showed a more homogenous distribution of the reinforcement. Yield and ultimate tensile strength increased when compared to those of pure Fe (from 400MPa and 416MPa to 523MPa and 630MPa, respectively). Electrochemical measurements and immersion tests indicated that the addition of Mg 2 Si could increase the corrosion rate of Fe even twice (from 0.14 to 0.28mm·year -1 ). It was found that the preparation method of the initial composite powders played a major role in the corrosion process as well as in the corrosion mechanism of the final composite. Copyright © 2017 Elsevier B.V. All rights reserved.

Microstructure and Magnetic Properties of Fe and Fe-alloy Thin Films Epitaxially Grown on MgO(100) Substrates

Energy Technology Data Exchange (ETDEWEB)

Matsubara, Katsuki; Ohtake, Mitsuru; Futamoto, Masaaki [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Kirino, Fumiyoshi, E-mail: matsubara@futamoto.elect.chuo-u.ac.jp [Graduate School of Fine Arts, Tokyo National University of Fine Arts and Music, 12-8 Ueno-koen, Taito-ku, Tokyo 110-8714 (Japan)

2011-07-06

Fe, Fe{sub 50}Co{sub 50}, and Fe{sub 80}Ni{sub 20} (at. %) single-crystal films with the (100){sub bcc} plane parallel to the substrate surface were prepared on MgO(100) single-crystals heated at 300 {sup 0}C by ultra high vacuum molecular beam epitaxy. The film growth mechanism, the film structure, and the magnetic properties were investigated. In-situ reflection high energy electron diffraction and X-ray diffraction analyses indicate that the strains in the films are very small though there are fairly large mismatches of -3.7{approx}-4.3% at the film/substrate interface. Cross-sectional high-resolution transmission electron microscopy shows that misfit dislocations are introduced in the film at the interface. Dislocations are also observed in the film up to around 10{approx}20 nm distance from the interface. The presence of such dislocation relieves the strain caused by the lattice mismatch. The in-plane magnetization properties of these films reflect the magnetocrystalline anisotropies of respective bulk Fe, Fe{sub 50}Co{sub 50}, and Fe{sub 80}Ni{sub 20} crystals.

Microstructure and Magnetic Properties of Fe and Fe-alloy Thin Films Epitaxially Grown on MgO(100) Substrates

International Nuclear Information System (INIS)

Matsubara, Katsuki; Ohtake, Mitsuru; Futamoto, Masaaki; Kirino, Fumiyoshi

2011-01-01

Fe, Fe 50 Co 50 , and Fe 80 Ni 20 (at. %) single-crystal films with the (100) bcc plane parallel to the substrate surface were prepared on MgO(100) single-crystals heated at 300 0 C by ultra high vacuum molecular beam epitaxy. The film growth mechanism, the film structure, and the magnetic properties were investigated. In-situ reflection high energy electron diffraction and X-ray diffraction analyses indicate that the strains in the films are very small though there are fairly large mismatches of -3.7∼-4.3% at the film/substrate interface. Cross-sectional high-resolution transmission electron microscopy shows that misfit dislocations are introduced in the film at the interface. Dislocations are also observed in the film up to around 10∼20 nm distance from the interface. The presence of such dislocation relieves the strain caused by the lattice mismatch. The in-plane magnetization properties of these films reflect the magnetocrystalline anisotropies of respective bulk Fe, Fe 50 Co 50 , and Fe 80 Ni 20 crystals.

Pile oscillator measurements of thermal absorption cross sections of Al, Mg, Fe and Cu; Mesure des sections efficaces thermiques d'absorption de l'Al, du Mg, du Fe et du Cu par la methode d'oscillation

Energy Technology Data Exchange (ETDEWEB)

Carre, J C; Vidal, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

The phase oscillation technique used at ZOE has the property of reducing of a marked factor the effect of neutron scattering by the sample. The absorption cross sections of poorly absorbing and highly scattering materials have been measured; for neutrons of 2,200 m/s, the following values are obtained: 229 {+-} 3 mb for Al; 64.2 {+-} 1.5 mb for Mg, 2.53 {+-} 0.03 b for Fe and 3.74 {+-} 0.04 b for Cu. (authors) [French] La methode d'oscillation de phase utilisee a ZOE possede la propriete de diminuer d'un facteur important l'influence de la diffusion. Les sections efficaces de capture de materiaux peu capturants et tres diffusants, ont ete mesurees; pour des neutrons de 2200 m/s, on obtient pour l'Al: 229 {+-} 3mb, pour le Mg: 64,2 {+-} 1,5 mb, pour le Fe: 2,53 {+-} 0,03 b et pour le Cu: 3,74 {+-} 0,04 b. (auteurs)

The influence of Co substitution on the magnetocaloric effect of Gd(Al,Fe)2

International Nuclear Information System (INIS)

Deng, J Q; Yan, J L; Huang, J L; Zhu, J M; Chen, X; Zhuang, Y H

2007-01-01

The magnetocaloric effect (MCE) in samples GdAl 1.7 (Fe 1-x Co x ) 0.3 with x= 0, 0.1, 0.2, 0.3 and 0.4 were investigated by x-ray diffraction (XRD) and magnetization measurements. It was found that five samples crystallize well in the MgCu 2 -type structure. The lattice parameter and the values of Curie temperature decrease with increasing Co content, whereas the magnetic-entropy change and cooling capacity increase. In the magnetic-field change of 2.0 T the maximum of the magnetic-entropy change and refrigerant capacity in sample GdAl 1.7 Fe 0.7 Co 0.3 reach 4.8 J kg -1 K -1 and 88.3 J kg -1 , respectively. The maximum of the magnetic-entropy change is comparable to that of Gd metal (3.8 J kg -1 K -1 in Δ B=1.5 T)

Efeitos da suplementação de fitase sobre a disponibilidade aparente de Mg, Ca, Zn, Cu, Mn e Fe em alimentos vegetais para a tilápia-do-nilo Effects of phytase supplementation on apparent availability of Mg, Ca, Zn, Cu, Mn, and Fe of plant feedstuffs for nile tilapia

Directory of Open Access Journals (Sweden)

Giovani Sampaio Gonçalves

2005-12-01

Full Text Available Cem juvenis de tilápia-do-nilo (Oreochromis niloticus; PV = 100.0 ± 5.0 g foram distribuídos em 10 tanques-rede com o objetivo de avaliar o efeito da suplementação da enzima fitase (0, 1.000 e 2.000 UFA/kg sobre a disponibilidade de minerais em alguns alimentos energéticos (milho, milho extrusado, farelo de trigo, farelo de arroz e farelo de sorgo e protéicos (farelo de soja extrusado, farelo de soja, farelo de girassol, farelo de algodão e glúten de milho utilizados na alimentação de tilápia-do-nilo (Oreochromis niloticus. Para determinação dos coeficientes de disponibilidade aparente (CDA do cálcio (Ca, magnésio (Mg, zinco (Zn, cobre (Cu, ferro (Fe e manganês (Mn, foram confeccionadas 31 rações, marcadas com 0,10% de óxido de crômio III uma referência (ração purificada e 30 contendo os dez alimentos e os diferentes níveis de suplementação da enzima fitase. O CDA dos nutrientes foi calculado com base no teor de crômio da ração e das fezes. A fitase aumenta, nos vegetais, a disponibilidade do Mg, Cu, Zn e Mn, os quais apresentam tendência diferenciada, em razão do seu valor biológico e do nível de suplementação de enzima.One hundred Nile tilapia juveniles (Oreochromis niloticus; BW= 100.0 ± 5.0 g were assigned to 10 experimental cages to evaluate the effects of phytase supplementation (0, 1,000, and 2,000 FTU/kg on calcium (Ca, magnesium (Mg, zinc (Zn, copper (Cu, iron (Fe and manganese (Mn availability of ten feedstuffs: five energetic (corn, extruded corn, wheat meal, rice meal and low-tannin sorghum and five protein (extruded soybean, soybean meal, sunflower meal, cottonseed meal and corn gluten meal. As reference, an albumin and gelatin-based diet [with 0.10 % chromic oxide (III as external marker] was fed to the juveniles. Thirty-one diets (one reference and 30 based on all feedstuffs and increasing levels of phytase were formulated to determine the coefficients of apparent availability of minerals (Mg

Analysis of Fe, Ca, Ti, Ba, Ce, Zr and La element in the Sea sediment at Muria peninsula by X RF method

International Nuclear Information System (INIS)

Sukirno and Sri Murniasih

2009-01-01

he analysis of metals (Fe, Ca, Ti, Ba, Ce, Zr and La) in the sea sediment environmental samples at Muria peninsula has been carried out with X-Ray Fluorescence (XRF) method. The aim of this analysis is to know the distribution metals which accommodate the recent environmental data in supporting the license of site and Environmental Impact Assessment (EIA) for the Nuclear Power Plants (NPP). Samples taken preparation and analysis based on the procedures of environmental analysis. The result analysis that contents of mayor elements in 7 sea sediment location of sampling were Ca, Ti and Fe with concentration are (6.74 – 11.69 ) %; (0.74 – 6.89 ) % and (0.45 -1.94 ) % successively; while minor elements were Ba, Ce, Zr and La with concentration are 451.4 – 1331.6 ) mg/kg; (201.8 – 427.3) mg/kg; (192.3 – 338.5) mg/kg dan (171.7 – 298.4) mg/kg. The statistic test result shows that sampling location there is a significant difference all of element with the level significant of 95 %. (author)

Tunable magnetic properties by interfacial manipulation of L1(0)-FePt perpendicular ultrathin film with island-like structures.

Science.gov (United States)

Feng, C; Wang, S G; Yang, M Y; Zhang, E; Zhan, Q; Jiang, Y; Li, B H; Yu, G H

2012-02-01

Based on interfacial manipulation of the MgO single crystal substrate and non-magnetic AIN compound, a L1(0)-FePt perpendicular ultrathin film with the structure of MgO/FePt-AIN/Ta was designed, prepared, and investigated. The film is comprised of L1(0)-FePt "magnetic islands," which exhibits a perpendicular magnetic anisotropy (PMA), tunable coercivity (Hc), and interparticle exchange coupling (IEC). The MgO substrate promotes PMA of the film because of interfacial control of the FePt lattice orientation. The AIN compound is doped to increase the difference of surface energy between FePt layer and MgO substrate and to suppress the growth of FePt grains, which takes control of island growth mode of FePt atoms. The AIN compound also acts as isolator of L1(0)-FePt islands to pin the sites of FePt domains, resulting in the tunability of Hc and IEC of the films.

Fe, Cr, Ni, Cu, Mg, Al, Ti, and S contents in plants and soil of heaps of nickel smelting works

Energy Technology Data Exchange (ETDEWEB)

Banasova, V; Hajduk, J

1977-01-01

The writers established the Fe, Ce, Cr, Ni, Ca, Mg, Al, Ti and S contents in the neopedon of heaps piling up from processing of nickel ore as well as in the plants: Cardaria draba, Salsola cali, Agropyrum repens, Bromus erectus, Calamagrostis epigeios, Cynodon dactylon and Matricaria inodora, growing on such heaps. Ca, Mg and S contents were found to be higher in dicotyledons and Fe, Al, Ti, Ni and Cr contents higher in monocotyledons. The analyzed dicotyledons appeared to be concentrators of Ca and S. Highest Fe, Al, Ti, Ni and Cr contents were found in individuals of the species Agropyrum repens. The neopedon as well as the plants had extraordinarily high Cr concentrations. The species Salsola cali has been found to possess an unusually higher affinity to the dump substrate after processing of nickel ore and to be a concentrator of Mg. 16 references, 1 table.

Designing MgFe{sub 2}O{sub 4} decorated on green mediated reduced graphene oxide sheets showing photocatalytic performance and luminescence property

Energy Technology Data Exchange (ETDEWEB)

Shetty, Krushitha [Department of Nanotechnology, PG Center, Bangalore Region, VIAT, VTU, Muddenahalli, Chikkaballapur 562101 (India); Dr. D. Premachandrasagar Centre for Advanced Materials, DSCE, Bangalore 560078 (India); Lokesh, S.V. [Department of Nanotechnology, PG Center, Bangalore Region, VIAT, VTU, Muddenahalli, Chikkaballapur 562101 (India); Rangappa, Dinesh, E-mail: dineshrangappa@gmail.com [Department of Nanotechnology, PG Center, Bangalore Region, VIAT, VTU, Muddenahalli, Chikkaballapur 562101 (India); Nagaswarupa, H.P., E-mail: nagaswarupa77@gmail.com [Research Center, Department of Science, East West Institute of Technology, Bangalore 560091 (India); Nagabhushana, H., E-mail: bhushanvlc@gmail.com [Prof. CNR Rao Centre for Advanced Materials, Tumkur University, Tumkur 572103 (India); Anantharaju, K.S., E-mail: iamananthkurupalya@gmail.com [Department of Chemistry, Dayananda Sagar College of Engineering, Shavige Malleshwara Hills, Kumaraswamy Layout, Bangalore 560078 (India); Dr. D. Premachandrasagar Centre for Advanced Materials, DSCE, Bangalore 560078 (India); Prashantha, S.C. [Research Center, Department of Science, East West Institute of Technology, Bangalore 560091 (India); Vidya, Y.S. [Department of Physics, Lal Bahadur Shastri Government First Grade College, Bangalore, 560032 (India); Sharma, S.C. [Dr. D. Premachandrasagar Centre for Advanced Materials, DSCE, Bangalore 560078 (India); Department of Mechanical Engineering, DSCE, Bangalore-560078 (India)

2017-02-15

Here, a green route has been reported to convert Graphene Oxide (GO) to reduced graphene oxide (RGO) using clove extract. A modest and eco-accommodating sol-gel strategy has been employed to prepare MgFe{sub 2}O{sub 4} nanoparticles, MgFe{sub 2}O{sub 4}–RGO nanocomposite samples. The samples were analyzed by Powder X-ray diffraction (PXRD), Fourier Transform Infrared Spectroscopy (FTIR), UV–Visible Spectroscopy, Scanning Electron Microcopy (SEM), Transmission Electron Microscopy (TEM), Photoluminescence (PL) and Electrochemical Impedance Spectroscopy (EIS). PXRD result revealed that the prepared samples were cubic spinel in nature. SEM results uncovered flake like surface morphology of the prepared nanomaterial. Better PL emission signature was observed when excited at 329 nm. PL studies demonstrated that the present samples were potential for the fabrication of white component of white light emitting diodes (WLEDs). Further, MgFe{sub 2}O{sub 4}–RGO nanocomposite showed enhanced photocatalytic movement (PCM) and photostability under Sunlight in the decomposition of Malachite Green (MG) compared to MgFe{sub 2}O{sub 4}. This can be attributed to the interaction of MgFe{sub 2}O{sub 4} surface with RGO sheets which results in PL quenching, demonstrates that the recombination of photo-induced electrons and holes in MgFe{sub 2}O{sub 4}–RGO nanocomposite is more effectively inhibited. A possible mechanism for the enhanced properties of MgFe{sub 2}O{sub 4}–RGO nanocomposite was discussed. Moreover, MgFe{sub 2}O{sub 4}–RGO photocatalyst also showed easy magnetic separation with high reusability. These results unveil that the synthesized sample can be used in display applications and also as a potential photocatalyst. - Graphical abstract: Green mediated reduced graphene oxide with MgFe{sub 2}O{sub 4} for display applications and also as a potential photocatalyst. - Highlights: • Synthesized GO was reduced to RGO by green route using clove extract. • MgFe

The ecological behaviour of 55Fe in plants and in the flesh of cattle and game

International Nuclear Information System (INIS)

Barwinek, F.; Kreuzer, W.; Sansoni, B.; Kernforschungsanlage Juelich G.m.b.H.

1980-01-01

98 samples of shrub lichens taken between 1965 and 1970, including 69 from the Federal Republic of Germany and 15 from Finland, mainly of the genus Cladonia, particularly the species Cladonia rangiferina and Cladonia silvatica, 5 samples of moss, 2 of heather and 4 of hay, and also meat samples taken from 12 Bavarian cattle slaughtered in the spring of 1970, 7 stags killed in the Eastern Carpathians in the autumn of 1969 and one chamois shot in the Lower Tauern mountains in the autumn of 1970, were all analysed for their contents of 55 Fe and stable Fe. The lichens contained between 0.7 - in 1970 - and a maximum of 139.0 nCi 55 Fe/kg dry matter - in 1965, or between 0.09 and 6.9 nCi/g ash. Their stable Fe contents varied between 0.234 and 1.990 mg/g dry matter or between 16.3 and 59.7 mg/Fe/g ash. Specific 55 Fe activities of between 231 pCi 55 Fe/mg Fe (1964) and 1.6 pCi 55 Fe/mg Fe (1970) can be calculated from these values. There were no obvious differences between the 55 Fe contamination of lichens of different species. This was also true of their contents of stable Fe. Cladonia furcata had the highest contents of 55 Fe and stable Fe, both relatively and absolutely. From 1965 onwards the 55 Fe-activities in the lichens examined declined in line with the drop in 55 Fe in the fall-out. (orig./AJ.) [de

Synthesis, characterization and adsorptive performance of MgFe{sub 2}O{sub 4} nanospheres for SO{sub 2} removal

Energy Technology Data Exchange (ETDEWEB)

Zhao Ling [Key Laboratory of Industrial Ecology and Environmental Engineering and State Key Laboratory of Fine Chemical, School of Environmental Sciences and Technology, Dalian University of Technology, Dalian 116024 (China); Li Xinyong, E-mail: xyli@dlut.edu.cn [Key Laboratory of Industrial Ecology and Environmental Engineering and State Key Laboratory of Fine Chemical, School of Environmental Sciences and Technology, Dalian University of Technology, Dalian 116024 (China); Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong); Zhao Qidong; Qu Zhenping; Yuan Deling [Key Laboratory of Industrial Ecology and Environmental Engineering and State Key Laboratory of Fine Chemical, School of Environmental Sciences and Technology, Dalian University of Technology, Dalian 116024 (China); Liu Shaomin [Department of Chemical Engineering, Curtin University of Technology, Perth, WA 6845 (Australia); Hu Xijun; Chen Guohua [Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong)

2010-12-15

A type of uniform Mg ferrite nanospheres with excellent SO{sub 2} adsorption capacity could be selectively synthesized via a facile solvothermal method. The size of the MgFe{sub 2}O{sub 4} nanospheres was controlled to be 300-400 nm in diameter. The structural, textural, and surface properties of the adsorbent have been fully characterized by a variety of techniques (Brunauer-Emmett-Teller, BET; X-ray diffraction analysis, XRD; scanning electron microscopy, SEM; and energy-dispersive X-ray spectroscopy, EDS). The valence states and the surface chemical compositions of MgFe{sub 2}O{sub 4} nanospheres were further identified by X-ray photoelectron spectroscopy (XPS). The behaviors of SO{sub 2} oxidative adsorption on MgFe{sub 2}O{sub 4} nanospheres were studied using Fourier transform infrared spectroscopy (FTIR). Both the sulfite and sulfate species could be formed on the surface of MgFe{sub 2}O{sub 4}. The adsorption equilibrium isotherm of SO{sub 2} was analyzed using a volumetric method at 298 K and 473 K. The results indicate that MgFe{sub 2}O{sub 4} nanospheres possess a good potential as the solid-state SO{sub 2} adsorbent for applications in hot fuel gas desulfurization.

External electric field driven modification of the anomalous and spin Hall conductivities in Fe thin films on MgO(001)

Science.gov (United States)

Pradipto, Abdul-Muizz; Akiyama, Toru; Ito, Tomonori; Nakamura, Kohji

2018-01-01

The effects of applying external electric fields to the anomalous and spin Hall conductivities in Fe thin-film models with different layer thicknesses on MgO(001) are investigated by using first-principles calculations. We observe that, for the considered systems, the application of positive electric field associated with the accumulation of negative charges on the Fe side generally decreases (increases) the anomalous (spin) Hall conductivities. The mapping of the Hall conductivities within the two-dimensional Brillouin zone shows that the electric-field-induced modifications are related to the modification of the band structures of the atoms at the interface with the MgO substrate. In particular, the external electric field affects the Hall conductivities via the modifications of the dx z,dy z orbitals, in which the application of positive electric field pushes the minority-spin states of the dx z,dy z bands closer to the Fermi level. Better agreement with the anomalous Hall conductivity for bulk Fe and a more realistic scenario for the electric field modification of Hall conductivities are obtained by using the thicker layers of Fe on MgO (Fe3/MgO and Fe5/MgO).

Evaluation of Pb and Fe tenors present in the sediments nearby the activities of taking advantage of lead-acid batteries

International Nuclear Information System (INIS)

Soares, Fernanda; Andrade, Crescencio; Monteiro, Carlos; Oliveira, Daniela; Valentim, Eliane

2011-01-01

The region chosen for this study was the Municipality of Belo Jardim, Pernambuco State, Brazil, which is considered an important industrial complex of the production and repairing of lead-acid batteries. Sediment samples were collected near to the illegal smelting industries and analyzed by ionic exchange method using a alpha-beta proportional counter for determining the activity of Pb-210, radionuclide used as geochronological tool. The chemical elements Pb and Fe were determined by means of flame atomic absorption spectrometry. The obtained results indicated an expressive increasing of lead and iron concentrations in the last 20 years. The concentrations in the sampled profile varied from 318 to 15487 mg.kg-1 and from 19 to 1524 mg.kg-1 for Fe and Pb, respectively. (author)

Shear response of Fe-bearing MgSiO3 post-perovskite at lower mantle pressures

Science.gov (United States)

METSUE, Arnaud; TSUCHIYA, Taku

2013-01-01

We investigate the shear response of possible slip systems activated in pure and Fe-bearing MgSiO3 post-perovskite (PPv) through ab initio generalized stacking fault (GSF) energy calculations. Here we show that the [100](001) slip system has the easiest response to plastic shear among ten possible slip systems investigated. Incorporation of Fe2+ decreases the strength of all slip systems but does not change the plastic anisotropy style. Therefore, pure and Fe-bearing MgSiO3 PPv should demonstrate similar LPO patterns with a strong signature of the [100](001) slip system. An aggregate with this deformation texture is expected to produce a VSH > VSV type polarization anisotropy, being consistent with seismological observations. PMID:23318681

Ag-loaded MgSrFe-layered double hydroxide/chitosan composite scaffold with enhanced osteogenic and antibacterial property for bone engineering tissue.

Science.gov (United States)

Cao, Dandan; Xu, Zhengliang; Chen, Yixuan; Ke, Qinfei; Zhang, Changqing; Guo, Yaping

2018-02-01

Bone tissue engineering scaffolds for the reconstruction of large bone defects should simultaneously promote osteogenic differentiation and avoid postoperative infection. Herein, we develop, for the first time, Ag-loaded MgSrFe-layered double hydroxide/chitosan (Ag-MgSrFe/CS) composite scaffold. This scaffold exhibits three-dimensional interconnected macroporous structure with a pore size of 100-300 μm. The layered double hydroxide nanoplates in the Ag-MgSrFe/CS show lateral sizes of 200-400 nm and thicknesses of ∼50 nm, and the Ag nanoparticles with particle sizes of ∼20 nm are uniformly dispersed on the scaffold surfaces. Human bone marrow-derived mesenchymal stem cells (hBMSCs) present good adhesion, spreading, and proliferation on the Ag-MgSrFe/CS composite scaffold, suggesting that the Ag and Sr elements in the composite scaffold have no toxicity to hBMSCs. When compared with MgFe/CS composite scaffold, the Ag-MgSrFe/CS composite scaffold has better osteogenic property. The released Sr 2+ ions from the composite scaffold enhance the alkaline phosphatase activity of hBMSCs, promote the extracellular matrix mineralization, and increase the expression levels of osteogenic-related RUNX2 and BMP-2. Moreover, the Ag-MgSrFe/CS composite scaffold possesses good antibacterial property because the Ag nanoparticles in the composite scaffold effectively prevent biofilm formation against S. aureus. Hence, the Ag-MgSrFe/CS composite scaffold with excellent osteoinductivity and antibacterial property has a great potential for bone tissue engineering. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 863-873, 2018. © 2017 Wiley Periodicals, Inc.

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

Science.gov (United States)

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

2016-04-01

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

Alteration of Basaltic Glass to Mg/Fe-Smectite under Acidic Conditions: A Potential Smectite Formation Mechanism on Mars

Science.gov (United States)

Peretyazhko, Tanya; Sutter, Brad; Ming, Douglas W.

2014-01-01

Phyllosilicates of the smectite group including Mg- and Fe-saponite and Fe(III)-rich nontronite have been identified on Mars. Smectites are believed to be formed under neutral to alkaline conditions that prevailed on early Mars. This hypothesis is supported by the observation of smectite and carbonate deposits in Noachian terrain on Mars. However, smectite may have formed under mildly acidic conditions. Abundant smectite formations have been detected as layered deposits hundreds of meters thick in intracrater depositional fans and plains sediments, while no large deposits of carbonates are found. Development of mildly acidic conditions at early Mars might allow formation of smectite but inhibit widespread carbonate precipitation. Little is known regarding the mechanisms of smectite formation from basaltic glass under acidic conditions. The objective of this study was to test a hypothesis that Mars-analogue basaltic glass alters to smectite minerals under acidic conditions (pH 4). The effects of Mg and Fe concentrations and temperature on smectite formation from basaltic glass were evaluated. Phyllosilicate synthesis was performed in batch reactors (Parr acid digestion vessel) under reducing hydrothermal conditions at 200 C and 100 C. Synthetic basaltic glass with a composition similar to that of the Gusev crater rock Adirondack (Ground surface APXS measurement) was used in these experiments. Basaltic glass was prepared by melting and quenching procedures. X-ray diffraction (XRD) analysis indicated that the synthesized glass was composed of olivine, magnetite and X-ray amorphous phase. Samples were prepared by mixing 250 mg Adirondack with 0.1 M acetic acid (final pH 4). In order to study influence of Mg concentration on smectite formation, experiments were performed with addition of 0, 1 and 10 mM MgCl2. After 1, 7 and 14 day incubations the solution composition was analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and the altered glass and formed

241Am, 137Cs, Sr and Pb uptake by tobacco as influenced by application of Fe chelators to soil

International Nuclear Information System (INIS)

Fuhrmann, Mark; Lanzirotti, Antonio

2005-01-01

To determine the potential for phytoextraction of 241 Am and other contaminants from soil, accumulation of 241 Am, 137 Cs, Sr, Fe, Al, Pb, and Mg by tobacco was determined for soil applications of two concentrations of ethylenediaminetetraacetic acid (EDTA), citric acid, and ascorbic acid. In tobacco receiving EDTA at 3.1 mmol/kg of soil, 241 Am content of plants averaged 15 Bq/kg (ranging up to 26 Bq/kg) while Fe concentrations became constant at 4.5 mmol/kg. Soil treatment with 18.8 mmol/kg EDTA resulted in average 241 Am concentrations of 29 Bq/kg (19 times higher than controls). Uptake of Pb was similar to 241 Am. In these samples, Fe increased to a maximum of almost 18 mmol/kg and 241 Am content increased linearly with both Fe and Al. Plants receiving ascorbic and citric acids took up smaller quantities of 241 Am, Pb, and Fe, even though these reagents were able to elute about as much Fe from the soil as EDTA. Synchrotron microbeam X-ray fluorescence (SXRF) was used to determine radial distributions of elements in roots and stems with and without EDTA treatment. SXRF maps indicate differences in behavior between Fe and Pb that are consistent with the bulk plant observations and provide insight into changes in metal content of the roots in the presence of EDTA

Ferromagnetic alloy material CoFeC with high thermal tolerance in MgO/CoFeC/Pt structure and comparable intrinsic damping factor with CoFeB

Science.gov (United States)

Chen, Shaohai; Zhou, Jing; Lin, Weinan; Yu, Jihang; Guo, Rui; Poh, Francis; Shum, Danny; Chen, Jingsheng

2018-02-01

The thermal tolerance and perpendicular magnetic anisotropy (PMA) of ferromagnetic alloy Co40Fe40C20 in the structure MgO/CoFeC/Pt (or Ta) were investigated and compared with the commonly used CoFeB alloy. It is found that the PMA of CoFeC with {{K}i,CoFeC}=2.21 erg c{{m}-2} , which is 59% higher than that of CoFeB, can be obtained after proper post-annealing treatment. Furthermore, CoFeC alloy provides better thermal tolerance to temperature of 400 °C than CoFeB. The studies on ferromagnetic resonance show that the intrinsic damping constant α in of Co40Fe40C20 alloy is 0.0047, which is similar to the reported value of 0.004 for Co40Fe40B20 alloy. The comprehensive comparisons indicate that CoFeC alloy is a promising candidate for the application of the integration of spin torque transfer magnetic random access memory with complementary metal-oxide semiconductor processes.

Study on adsorption of O2 on LaFe1−xMgxO3 (0 1 0) surface by density function theory calculation

International Nuclear Information System (INIS)

Liu, Xing; Cheng, Bin; Hu, Jifan; Qin, Hongwei

2012-01-01

Highlights: ► Mg-doping can change the electronic properties of LaFeO 3 (0 1 0) surface by decreasing the band gap. ► The position and content of Mg-doping can both affect the ability to adsorb O 2 . ► The strong hybridization between O 2 p and Fe d orbital is the origin of binding mechanism. - Abstract: The adsorption of O 2 on the clean and Mg doped LaFeO 3 (0 1 0) surface has been investigated using the density functional theory (DFT) method. Calculation results show that Mg-doping can change the electronic properties of LaFeO 3 (0 1 0) surface by decreasing the band gap. When Mg ions were not on the first layer of the surface, with increasing Mg content the adsorption of O 2 was enhanced. When Mg ions were on the first layer, the adsorption of O 2 was weakened with the increase of Mg content. The analysis results of the DOS indicated that the Mg ion and adsorbed O 2 had no strong hybridization, and the bonding mechanism was originated from the strong hybridization between the O p and Fe d orbital. Referring to all the calculation results, it was found that except for the increase of stability of oxygen adsorption, the Mg doping could not improve the sensitivity to O 2 .

Formation of Fe- and Mg-Rich Smectite under Hyperalkaline Conditions at Narra in Palawan, the Philippines

OpenAIRE

Shimbashi, Misato; Sato, Tsutomu; Yamakawa, Minoru; Fujii, Naoki; Otake, Tsubasa

2018-01-01

The formation of Fe- and Mg-rich smectite and zeolite under alkaline conditions, as secondary minerals after the alkaline alteration of bentonite in repositories for radioactive waste, is of major concern. It is crucial for safety assessments to know whether smectite is formed as a secondary mineral after the alkaline alteration of bentonite. In the present paper, Fe- and Mg-rich smectite, which interacted with the hyperalkaline groundwater at Narra in Palawan, Philippines, was used. Mineralo...

effet de la toxicite du fer sur l'activite photosynthetique du riz

African Journals Online (AJOL)

AISA

est utilisée dans les réactions photochimiques de la photosynthèse, une deuxième dissipée .... 4,7 ; C organique, 1,87 % ; P total, 226 mg kg-1 ; K, 325 mg kg-1 ; Ca, 68 mg kg-1 ; Fe, 3 mg kg-1) et à Korhogo (pHH2O, 5,9 ; pHKCl, 4,1. ; C organique, 1,02 % ; P total, 192 mg kg-1 ;. K, 310 mg kg-1 ; Ca, 64 mg kg-1 ; Fe, 7 mg ...

Microstructural evolution of Fe-rich particles in an Al-Zn-Mg-Cu alloy during equal-channel angular pressing

International Nuclear Information System (INIS)

Sha, G.; Wang, Y.B.; Liao, X.Z.; Duan, Z.C.; Ringer, S.P.; Langdon, T.G.

2010-01-01

The microstructures of a severely deformed Al-Zn-Mg-Cu (AA7136) alloy have been characterized carefully using transmission electron microscopy and three-dimensional atom probe analysis. The Fe-rich intermetallic particles are predominantly Al 13 Fe 4 type in the as-extruded alloy. Significantly, equal-channel angular pressing (ECAP) at 200 deg. C refines Fe-rich particles from ∼1 to 2 μm to as small as ∼50 nm after 4 passes processing, and effectively narrow down their size distribution with the increase of number of ECAP passes. In addition, small Fe-rich particles evolve into spherical morphology and are in a more uniform distribution. The formations of Fe-rich phases in AA7136, the kinetic and thermodynamic effects in relation to the refinement of Fe-rich particles and their morphology evolution during ECAP processing are discussed.

Heat generation ability in AC magnetic field of nano MgFe2O4-based ferrite powder prepared by bead milling

International Nuclear Information System (INIS)

Hirazawa, Hideyuki; Aono, Hiromichi; Naohara, Takashi; Maehara, Tsunehiro; Sato, Mitsunori; Watanabe, Yuji

2011-01-01

Nanosized MgFe 2 O 4 -based ferrite powder having heat generation ability in an AC magnetic field was prepared by bead milling and studied for thermal coagulation therapy applications. The crystal size and the particle size significantly decreased by bead milling. The heat generation ability in an AC magnetic field improved with the milling time, i.e. a decrease in crystal size. However, the heat generation ability decreased for excessively milled samples with crystal sizes of less than 5.5 nm. The highest heat ability (ΔT=34 o C) in the AC magnetic field (370 kHz, 1.77 kA/m) was obtained for fine MgFe 2 O 4 powder having a ca. 6 nm crystal size (the samples were milled for 6-8 h using 0.1 mm φ beads). The heat generation of the samples was closely related to hysteresis loss, a B-H magnetic property. The reason for the high heat generation properties of the samples milled for 6-8 h using 0.1 mm φ beads was ascribed to the increase in hysteresis loss by the formation of a single domain. Moreover, the improvement in heating ability was obtained by calcination of the bead-milled sample at low temperature. In this case, the maximum heat generation (ΔT=41 o C) ability was obtained for a ca. 11 nm crystal size sample was prepared by crystal growth during the sample calcination. On the other hand, the ΔT value for Mg 0.5 Ca 0.5 Fe 2 O 4 was synthesized using a reverse precipitation method decreased by bead milling. - Research Highlights: →The crystal and particle size for MgFe 2 O 4 based ferrite were decreased by bead milling. →The highest heat ability was obtained for MgFe 2 O 4 having a ca. 6 nm crystal size. →This high heat generation ability was ascribed to the increase in hysteresis loss. →Hysteresis loss was increased by the formation of a single domain.

Cafeína (150 mg/kg y aprendizaje espacial (retención y adquisición en ratones

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María del Pilar Santacruz

2003-01-01

Full Text Available En este trabajo se evaluó el papel que juega la cafeína (150mg/kg en el aprendizaje espacial (adquisición y retención en ratones mediante las mediciones de la latencia de salida, velocidad, aciertos, regresos, errores y excretas en un laberinto de 3 x 3 metros. Los sujetos fueron moldeados para una ruta en el laberinto y luego se aleatorizaron 20 machos y 20 hembras para la administración de cafeína (s.c. y solución salina durante ocho días consecutivos; luego se observó la retención de este aprendizaje y se moldeó otra ruta para evaluar su retención 24 horas después: La cafeína incrementó la retención del aprendizaje 1, donde hubo los mayores aciertos, y en el segundo las hembras con cafeína exhibieron mayor velocidad y aciertos mientras que los machos, presentaron menores aciertos y velocidad que todos los grupos; como vemos, en el segundo caso, la cafeína fortaleció la retención del aprendizaje 2 en las hembras y la debilitó en los machos. Se concluye que la cafeína (150mg/kg influyó positivamente en la retención del aprendizaje espacial, mas no en la adquisición. Este artículo está asociado a la línea de investigación en Cafeína y Cognición de la Universidad de la Sabana.

First principles study of structural, electronic, magnetic and elastic properties of Mg{sub 0.75}TM{sub 0.25}S (TM=Mn, Fe, Co, Ni)

Energy Technology Data Exchange (ETDEWEB)

Gous, M.H., E-mail: gousph@hotmail.fr; Meddour, A., E-mail: a_meddour@yahoo.fr; Bourouis, Ch., E-mail: bourouisse_ch@yahoo.fr

2017-01-15

The objective of this work is to predict the structural, electronic, magnetic and elastic properties of Mg{sub 1−x}TM{sub x}S (TM=Mn, Fe, Co and Ni) compound in the zinc blende Ferromagnetic phase using first principal approach. The structural and elastic properties are performed using the generalized gradient approximation proposed by Wu and Cohen(WC-GGA). However, the electronic and magnetic properties have been performed using modified Becke-Johnson potential combined with the LDA correlation (mBJLDA). The results show that all compounds Mg{sub 1−x}Mn{sub x}S, Mg{sub 1−x}Fe{sub x}S and Mg{sub 1−x}Ni{sub x}S exhibit a half-metallic ferromagnetic character with 100% spin-polarization at the Fermi level, except Mg{sub 1−x}Co{sub x}S is a metal. For each compounds study here, the total magnetic momentum is an integer equal to magnetic moments of TM atom in their free space charge value. Due to the p–d hybridization, there is a small local magnetic moment on the Mg and S sites; whereas, the local magnetic moments of TM atom reduce from their free space charge value. In addition, we investigate the mechanical behavior of MgS and Mg{sub 1−x}TM{sub x}S; all compounds studied here are mechanically stable and exhibit a strong anisotropic behavior. - Highlights: • Our results could be a prediction for coming works. • According to our results of electronic properties: Mg{sub 0.75}Co{sub 0.25}S is metal. Mg{sub 0.75}Mn{sub 0.25}S, Mg{sub 0.75}Fe{sub 0.25}S and Mg{sub 0.75}Ni{sub 0.25}S exhibit half-metallic ferromagnetic behavior with 100% spin polarization at Fermi level. • We found that MgS and Mg{sub 0.75}TM{sub 0.25}S (TM=Mn, Fe, Co and Ni) compounds are mechanically stable, ductile materials and have an anisotropic Young's Modulus. • It is likely that these materials have a high Curie temperature.

Flux pinning and inhomogeneity in magnetic nanoparticle doped MgB2/Fe wires

Science.gov (United States)

Novosel, Nikolina; Pajić, Damir; Mustapić, Mislav; Babić, Emil; Shcherbakov, Andrey; Horvat, Joseph; Skoko, Željko; Zadro, Krešo

2010-06-01

The effects of magnetic nanoparticle doping on superconductivity of MgB2/Fe wires have been investigated. Fe2B and SiO2-coated Fe2B particles with average diameters 80 and 150 nm, respectively, were used as dopands. MgB2 wires with different nanoparticle contents (0, 3, 7.5, 12 wt.%) were sintered at temperature 750°C. The magnetoresistivity and critical current density Jc of wires were measured in the temperature range 2-40 K in magnetic field B doped wires decreases quite rapidly with doping level (~ 0.5 K per wt.%). This results in the reduction of the irreversibility fields Birr(T) and critical current densities Jc(B,T) in doped samples (both at low (5 K) and high temperatures (20 K)). Common scaling of Jc(B,T) curves for doped and undoped wires indicates that the main mechanism of flux pinning is the same in both types of samples. Rather curved Kramer's plots for Jc of doped wires imply considerable inhomogeneity.

Phase formation, morphology and magnetic properties of MgFe{sub 2}O{sub 4} nanoparticles synthesized by hydrothermal technique

Energy Technology Data Exchange (ETDEWEB)

Nonkumwong, Jeeranan [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Ananta, Supon [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Jantaratana, Pongsakorn [Department of Physics, Faculty of Science, Kasetsart University, Bangkok 11900 (Thailand); Phumying, Santi; Maensiri, Santi [Advanced Materials Physics Laboratory (Amp.), School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); Srisombat, Laongnuan, E-mail: slaongnuan@yahoo.com [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

2015-05-01

In the present work, the processing conditions for obtaining monodispersed magnesium ferrite (MgFe{sub 2}O{sub 4}) nanoparticles with the desired morphology and relatively high saturation magnetization via hydrothermal technique were developed. For the first time, the effects of base type and reaction conditions (i.e. temperature and time) on phase formation, morphology and magnetic properties of the obtained products were determined by using a combination of XRD, TEM/EDX and VSM techniques. It is seen that the saturation magnetization of the particles can be increased by employing lower reaction temperature and/or shorter reaction time, while narrow size distribution of the particles can be maintained. In addition, it was found that pure phase of superparamagnetic MgFe{sub 2}O{sub 4} nanoparticles with the smallest size of about 65 nm was obtained by using CH{sub 3}COONa as a base at 180 °C for 14 h. - Highlights: • Preparation of MgFe{sub 2}O{sub 4} nanoparticles by hydrothermal method. • Effects of base and reaction conditions on formation and morphology MgFe{sub 2}O{sub 4} particles. • Producing the 65 nm MgFe{sub 2}O{sub 4} nanoparticles with superparamagnetic property.

Surface and local electronic structure modification of MgO film using Zn and Fe ion implantation

Science.gov (United States)

Singh, Jitendra Pal; Lim, Weon Cheol; Lee, Jihye; Song, Jonghan; Lee, Ik-Jae; Chae, Keun Hwa

2018-02-01

Present work is motivated to investigate the surface and local electronic structure modifications of MgO films implanted with Zn and Fe ions. MgO film was deposited using radio frequency sputtering method. Atomic force microscopy measurements exhibit morphological changes associated with implantation. Implantation of Fe and Zn ions leads to the reduction of co-ordination geometry of Mg2+ ions in host lattice. The effect is dominant at bulk of film rather than surface as the large concentration of implanted ions resides inside bulk. Moreover, the evidences of interaction among implanted ions and oxygen are not being observed using near edge fine structure measurements.

Saturation of VCMA in out-of-plane magnetized CoFeB/MgO/CoFeB magnetic tunnel junctions

Science.gov (United States)

Williamson, M.; de Rozieres, M.; Almasi, H.; Chao, X.; Wang, W.; Wang, J.-P.; Tsoi, M.

2018-05-01

Voltage controlled magnetic anisotropy (VCMA) currently attracts considerable attention as a novel method to control and manipulate magnetic moments in high-speed and low-power spintronic applications based on magnetic tunnel junctions (MTJs). In our experiments, we use ferromagnetic resonance (FMR) to study and quantify VCMA in out-of-plane magnetized CoFeB/MgO/CoFeB MTJ pillars. FMR is excited by applying a microwave current and detected via a small rectified voltage which develops across MTJ at resonance. The VCMA effective field can be extracted from the measured resonance field and was found to vary as a function of electrical bias applied to MTJ. At low applied biases, we observe a linear shift of the VCMA field as a function of the applied voltage which is consistent with the VCMA picture based on the bias-induced electron migration across the MgO/CoFeB interface. At higher biases, both positive and negative, we observe a deviation from the linear behavior which may indicate a saturation of the VCMA effect. These results are important for the design of MTJ-based applications.

Structural and magnetic properties of Ni0.15Mg0.1Cu0.3Zn0.45Fe2O4 ferrite prepared by NaOH-precipitation method

International Nuclear Information System (INIS)

Hou, Wei-xiao; Wang, Zhi

2015-01-01

Highlights: • NiMgCuZn ferrites were successfully prepared by low-temperature sintering. • NiMgCuZn ferrites have the advantages of both NiCuZn and MgCuZn ferrites. • NiMgCuZn ferrites exhibit high Curie temperature & high stability of permeability. - Abstract: The Ni 0.15 Mg 0.1 Cu 0.3 Zn 0.45 Fe 2 O 4 ferrite powders have been prepared by NaOH co-precipitation method and characterized by X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The XRD patterns confirm the single phase spinel structure of synthesized nanoparticles. The average crystallite size of the particles increases from 12 to 36 nm with calcining temperature (T a ) from 500 to 800 °C. The saturation magnetization (M s ) of the superparamagnetic particles was deduced by Langevin theory. Subsequently, the densification characteristics and magnetic properties of the low-temperature 950 °C-sintered ferrite bulk samples were also investigated. The magnetic measurement showed that the sintered bulk sample of T a = 600 °C has the highest initial permeability (μ i ), lowest coercivity (H c ), largest saturation magnetization (M s ) and satisfactory thermal stability of μ i . The microstructures of sintered samples were examined using field emission scanning electric microscope (FESEM). The T a has significant influence on the bulk density, initial permeability, saturation magnetization and coercivity of Ni 0.15 Mg 0.1 Cu 0.3 Zn 0.45 Fe 2 O 4 ferrite

Anomalous spin-dependent tunneling statistics in Fe/MgO/Fe junctions induced by disorder at the interface

Science.gov (United States)

Yan, Jiawei; Wang, Shizhuo; Xia, Ke; Ke, Youqi

2018-01-01

We present first-principles analysis of interfacial disorder effects on spin-dependent tunneling statistics in thin Fe/MgO/Fe magnetic tunnel junctions. We find that interfacial disorder scattering can significantly modulate the tunneling statistics in the minority spin of the parallel configuration (PC) while all other spin channels remain dominated by the Poissonian process. For the minority-spin channel of PC, interfacial disorder scattering favors the formation of resonant tunneling channels by lifting the limitation of symmetry conservation at low concentration, presenting an important sub-Poissonian process in PC, but is destructive to the open channels at high concentration. We find that the important modulation of tunneling statistics is independent of the type of interfacial disorder. A bimodal distribution function of transmission with disorder dependence is introduced and fits very well our first-principles results. The increase of MgO thickness can quickly change the tunneling from a sub-Poissonian to Poissonian dominated process in the minority spin of PC with disorder. Our results provide a sensitive detection method of an ultralow concentration of interfacial defects.

Isopiestic Investigation of the Osmotic and Activity Coefficients of {yMgCl2 + (1 - y)MgSO4}(aq) and the Osmotic Coefficients of Na2SO4.MgSO4(aq) at 298.15 K

Energy Technology Data Exchange (ETDEWEB)

Miladinovic, J; Ninkovic, R; Todorovic, M; Rard, J A

2007-06-06

Isopiestic vapor pressure measurements were made for {l_brace}yMgCl{sub 2} + (1-y)MgSO{sub 4}{r_brace}(aq) solutions with MgCl{sub 2} ionic strength fractions of y = 0, 0.1997, 0.3989, 0.5992, 0.8008, and (1) at the temperature 298.15 K, using KCl(aq) as the reference standard. These measurements for the mixtures cover the ionic strength range I = 0.9794 to 9.4318 mol {center_dot} kg{sup -1}. In addition, isopiestic measurements were made with NaCl(aq) as reference standard for mixtures of {l_brace}xNa{sub 2}SO{sub 4} + (1-x)MgSO{sub 4}{r_brace}(aq) with the molality fraction x = 0.50000 that correspond to solutions of the evaporite mineral bloedite (astrakanite), Na{sub 2}Mg(SO{sub 4}){sub 2} {center_dot} 4H{sub 2}O(cr). The total molalities, m{sub T} = m(Na{sub 2}SO{sub 4}) + m(MgSO{sub 4}), range from m{sub T} = 1.4479 to 4.4312 mol {center_dot} kg{sup -1} (I = 5.0677 to 15.509 mol {center_dot} kg{sup -1}), where the uppermost concentration is the highest oversaturation molality that could be achieved by isothermal evaporation of the solvent at 298.15 K. The parameters of an extended ion-interaction (Pitzer) model for MgCl2(aq) at 298.15 K, which were required for an analysis of the {l_brace}yMgCl{sub 2} + (1-y)MgSO{sub 4}{r_brace}(aq) mixture results, were evaluated up to I = 12.025 mol {center_dot} kg{sup -1} from published isopiestic data together with the six new osmotic coefficients obtained in this study. Osmotic coefficients of {l_brace}yMgCl{sub 2} + (1-y)MgSO{sub 4}{r_brace}(aq) solutions from the present study, along with critically-assessed values from previous studies, were used to evaluate the mixing parameters of the extended ion-interaction model.

Synthesized of PEG-6000 coated MgFe2O4 nanoparticles based on natural iron sand by co-precipitation method

Science.gov (United States)

Setiadi, E. A.; Simbolon, S.; Saputra, A. S. P.; Marlianto, E.; Djuhana; Kurniawan, C.; Yunus, M.; Sebayang, P.

2018-02-01

The polymer coated Magnesium Ferrite nanoparticles (MgFe2O4) based on natural iron sand, Mg(CH3COO)2.4H2O, and PEG-6000 have been successfully prepared by co-precipitation method. The mass variation of PEG-6000 content was from 0 to 12 gram. It was prepared at synthesize temperature of 70°C. The PEG coating reduced the effect of agglomeration, so the coercivity value can be closed to soft magnets. The nanoparticle of synthesized has MgFe2O4 single phase and cubic spinel structure. The bonding of MgFe2O4 and PEG-6000 as a coating material was confirmed by FTIR curve. The MgFe2O4 density decreased with the increasing of PEG 6000 content. On the other hand, the coercivity value was slightly reduced as the addition of PEG-6000, with the lowest value was obtained on 8 gram PEG content. The optimum condition is obtained at addition of 8 gram PEG 6000 to MgFe2O4, with coercivity, saturation, and remanence are 198.41 Oe, 52.53 emu/g, and 8.51 emu/g, respectively. So that, the sample is widely used as absorbance material of heavy metal.

Magnetic and Moessbauer study of Mg{sub 0.9}Mn{sub 0.1}Cr{sub x}Fe{sub 2-x}O{sub 4} ferrites

Energy Technology Data Exchange (ETDEWEB)

Elzain, M., E-mail: elzain@squ.edu.om; Widatallah, H.; Gismelseed, A.; Bouziane, K.; Yousif, A.; Al Rawas, A.; Al-Omari, I.; Sellai, A. [Sultan Qaboos University, Department of Physics, College of Science (Oman)

2006-02-15

The ferrites Mg{sub 0.9}Mn{sub 0.1}Cr{sub x}Fe{sub 2-x}O{sub 4} (0x0.9) were prepared using the conventional double sintering method. The XRD showed that the samples maintain a single spinel cubic phase. The Moessbauer measurements were carried out at room and liquid nitrogen temperatures. From the area ratios of the A and B sites, it was found that the Fe cation population of the A and B sites decreases in proportion to Cr concentration. The contact hyperfine fields at the A and B sites were found to decrease with increasing Cr contents. This was found to be in approximate agreement with the results of magnetization measurement. The distributions of Mg and Mn cations versus Cr concentration were also determined using the Moessbauer and magnetization results. The Curie temperatures were determined and found to agree with the reported values. As the Cr contents increases the relative magnetization, was found to increase at low temperatures and decreases at higher temperatures.

Five-year field results and long-term effectiveness of 20 mg/kg liposomal amphotericin B (Ambisome for visceral leishmaniasis in Bihar, India.

Directory of Open Access Journals (Sweden)

Sakib Burza

Full Text Available BACKGROUND: Visceral Leishmaniasis (VL; also known as Kala-azar is an ultimately fatal disease endemic in Bihar. A 2007 observational cohort study in Bihar of 251 patients with VL treated with 20 mg/Kg intravenous liposomal amphotericin B (Ambisome demonstrated a 98% cure rate at 6-months. Between July 2007 and August 2012, Médecins Sans Frontières (MSF and the Rajendra Memorial Research Institute (RMRI implemented a VL treatment project in Bihar, India-an area highly endemic for Leishmania donovani-using this regimen as first-line treatment. METHODS AND PRINCIPAL FINDINGS: Intravenous Ambisome 20 mg/kg was administered in four doses of 5 mg/kg over 4-10 days, depending on the severity of disease. Initial clinical cure at discharge was defined as improved symptoms, cessation of fever, and recession of spleen enlargement. This observational retrospective cohort study describes 8749 patients with laboratory-confirmed primary VL treated over a 5-year period: 1396 at primary healthcare centers, 7189 at hospital, and 164 at treatment camps. Initial clinical cure was achieved in 99.3% of patients (8692/8749; 0.3% of patients (26/8749 defaulted from treatment and 0.4% (31/8749 died. Overall, 1.8% of patients (161/8749 were co-infected with HIV and 0.6% (51/8749 with tuberculosis. Treatment was discontinued because of severe allergic reactions in 0.1% of patients (7/8749. Overall, 27 patients (0.3% were readmitted with post Kala-azar dermal leishmaniasis (PKDL. Risk factors for late presentation included female sex, age >15 years and being from a scheduled caste. In 2012, a long-term efficacy survey in the same area of Bihar determined relapse rates of VL after 5 years' intervention with Ambisome. Of 984 immunocompetent patients discharged between September 2010 and December 2011, 827 (84.0% were traced in order to determine their long-term outcomes. Of these, 20 patients (2.4% had relapsed or received further treatment for VL. Of those completing 6

Surface structure of MgO underlayer with Ti diffusion for (002 oriented L10 FePt-based heat assisted magnetic recording media

Directory of Open Access Journals (Sweden)

Sintaro Hinata

2018-05-01

Full Text Available Surface morphology of the MgO layer and magnetic properties of FePt-C layer deposited on the MgO were investigated for the FePt-based heat assisted magnetic recording media. Stacking structure of the underlayer for the FePt-C layer was MgO (0-5 nm/Cr80Mn20 (0-30 nm/Cr50Ti50 (0-50 nm/glass sub.. Surface observation result for the MgO film by using an atomic force microscope revealed the existence of nodules with a height of about 2 nm and a network-like convex structure with a height difference of about sub nm (boundary wall, BW on the MgO crystal grain boundary. Density of the nodules largely depends on the surface roughness of the CrTi layer, RaCrTi and it is suppressed from 10 to 2/0.5 μm2 by reducing RaCrTi from 420 to 260 pm. Height of the BW depends on thickness of the MgO layer, tMgO and it can be suppressed by reducing tMgO to less than 4 nm. From the cross-sectional energy dispersive x-ray mapping, it is clarified that the BW is formed by atomic diffusion of Ti atoms from CrTi layer due to the substrate heating process, and a compound consists of Mg, Ti and O atoms. This BW can be used as a template to magnetically isolate the FePt column in the FePt-based granular film, such as FePt-SiO2, if the size of the BW is reduced to less than 10 nm. M-H loop of the FePt-C granular film deposited on the underlayer showed that the nodule and BW induce oxidation of the FePt grains, and reduction of intergranular exchange coupling.

Surface structure of MgO underlayer with Ti diffusion for (002) oriented L10 FePt-based heat assisted magnetic recording media

Science.gov (United States)

Hinata, Sintaro; Jo, Shin; Saito, Shin

2018-05-01

Surface morphology of the MgO layer and magnetic properties of FePt-C layer deposited on the MgO were investigated for the FePt-based heat assisted magnetic recording media. Stacking structure of the underlayer for the FePt-C layer was MgO (0-5 nm)/Cr80Mn20 (0-30 nm)/Cr50Ti50 (0-50 nm)/glass sub.. Surface observation result for the MgO film by using an atomic force microscope revealed the existence of nodules with a height of about 2 nm and a network-like convex structure with a height difference of about sub nm (boundary wall, BW) on the MgO crystal grain boundary. Density of the nodules largely depends on the surface roughness of the CrTi layer, RaCrTi and it is suppressed from 10 to 2/0.5 μm2 by reducing RaCrTi from 420 to 260 pm. Height of the BW depends on thickness of the MgO layer, tMgO and it can be suppressed by reducing tMgO to less than 4 nm. From the cross-sectional energy dispersive x-ray mapping, it is clarified that the BW is formed by atomic diffusion of Ti atoms from CrTi layer due to the substrate heating process, and a compound consists of Mg, Ti and O atoms. This BW can be used as a template to magnetically isolate the FePt column in the FePt-based granular film, such as FePt-SiO2, if the size of the BW is reduced to less than 10 nm. M-H loop of the FePt-C granular film deposited on the underlayer showed that the nodule and BW induce oxidation of the FePt grains, and reduction of intergranular exchange coupling.

Time scales of bias voltage effects in FE/MgO-based magnetic tunnel junctions with voltage-dependent perpendicular anisotropy

International Nuclear Information System (INIS)

Lytvynenko, Ia.M.; Hauet, T.; Montaigne, F.; Bibyk, V.V.; Andrieu, S.

2015-01-01

Interplay between voltage-induced magnetic anisotropy transition and voltage-induced atomic diffusion is studied in epitaxial V/Fe (0.7 nm)/ MgO/ Fe(5 nm)/Co/Au magnetic tunnel junction where thin Fe soft electrode has in-plane or out-of-plane anisotropy depending on the sign of the bias voltage. We investigate the origin of the slow resistance variation occurring when switching bias voltage in opposite polarity. We demonstrate that the time to reach resistance stability after voltage switching is reduced when increasing the voltage amplitude or the temperature. A single energy barrier of about 0.2 eV height is deduced from temperature dependence. Finally, we demonstrate that the resistance change is not correlated to a change in soft electrode anisotropy. This conclusion contrasts with observations recently reported on analogous systems. - Highlights: • Voltage-induced time dependence of resistance is studied in epitaxial Fe/MgO/Fe. • Resistance change is not related to the bottom Fe/MgO interface. • The effect is thermally activated with an energy barrier of the order of 0.2 eV height

Hydrogen storage in Mg-Ni-Fe compounds prepared by melt spinning and ball milling

Energy Technology Data Exchange (ETDEWEB)

Palade, P. [Settore Materiali, Dipartimento di Ingegneria Meccanica, Universita di Padova, via Marzolo 9, 35131 Padova (Italy); National Institute for Physics of Materials, Atomistilor 105 bis, P.O. Box MG-7, 077125 Bucharest-Magurele (Romania); Sartori, S. [Settore Materiali, Dipartimento di Ingegneria Meccanica, Universita di Padova, via Marzolo 9, 35131 Padova (Italy); Maddalena, A. [Settore Materiali, Dipartimento di Ingegneria Meccanica, Universita di Padova, via Marzolo 9, 35131 Padova (Italy); Principi, G. [Settore Materiali, Dipartimento di Ingegneria Meccanica, Universita di Padova, via Marzolo 9, 35131 Padova (Italy)]. E-mail: giovanni.principi@unipd.it; Lo Russo, S. [Dipartimento di Fisica, Universita di Padova, Via Marzolo 8, 35131 Padova (Italy); Lazarescu, M. [National Institute for Physics of Materials, Atomistilor 105 bis, P.O. Box MG-7, 077125 Bucharest-Magurele (Romania); Schinteie, G. [National Institute for Physics of Materials, Atomistilor 105 bis, P.O. Box MG-7, 077125 Bucharest-Magurele (Romania); Kuncser, V. [National Institute for Physics of Materials, Atomistilor 105 bis, P.O. Box MG-7, 077125 Bucharest-Magurele (Romania); Filoti, G. [National Institute for Physics of Materials, Atomistilor 105 bis, P.O. Box MG-7, 077125 Bucharest-Magurele (Romania)

2006-05-18

Magnesium-rich Mg-Ni-Fe intermetallic compounds have been prepared by two different routes: (a) short time ball milling of ribbons obtained by melt spinning; (b) long time ball milling of a mixture of MgH{sub 2}, Ni and Fe powders. The first type of samples displays an hydrogen desorption kinetics better than the second one. Pressure composition isotherm measurements exhibit for both type of samples two plateaux, the lower and wider corresponding to the MgH{sub 2} phase and the upper and shorter corresponding to the Mg{sub 2}NiH{sub 4} phase. The presence of the two types of hydrides is confirmed by X-ray diffraction analysis. Moessbauer spectroscopy shows that in melt spun and subsequently milled samples iron is mainly in a disordered structure and segregates after hydrogenation, while in directly milled powders remains mainly unalloyed. After multiple hydrogen absorption/desorption cycles the main part of iron is in metallic state in samples of both types, those of first type preserving better hydrogen desorption kinetics.

Magnetic properties of soft layer/FePt-MgO exchange coupled composite Perpendicular recording media

Institute of Scientific and Technical Information of China (English)

Yin Jin-Hua; Takao Suzuki; Pan Li-Qing

2008-01-01

The magnetic properties of exchange coupled composite(ECC)media that are composed of perpendicular magnetic recording media FePt-MgO and two kinds of soft layers have been studied by using an x-ray diffractometer,a polar Kerr magneto-optical system(PMOKE)and a vibrating sample magnetometer(VSM).The results show that ECC media can reduce the coercivities of perpendicular magnetic recording media FePt-MgO.The ECC media with granular-type soft layers have weaker exchange couplings between magnetic grains and the magnetization process,for ECC media of this kind mainly follow the Stoner-Wohlfarth model.

Radioactivity of β / γ and the Content of Ca, Fe, Mn, Mg, Na on the Spring of Ponorogo East Java Lime Area

International Nuclear Information System (INIS)

Sutjipto

2002-01-01

Radioactivity of β / γ and the content of Ca, Fe, Mn, Mg, Na on the source of Ponorogo East-Java lime area has been studied. This research was carried out to know radioactivity of β / γ and the content of Ca, Fe, Mn, Mg, Na on the spring of different three places were Ngebel-lake source, Ngembak source and Gonggang source. Samples taken, preparation and analysis based on the procedures of environmental radioactivity analysis and water sampling guidelines. The instrument used for the analysis radioactivity were low level β counter modified P3TM-BATAN Yogyakarta with detector GM and spectrometer γ with detector Ge(Li). Radioactivity of β (gross) from the source of different three places (β ≤ 1 Bq/L) are lower than the value of PPRI No. 20/1990. Radioactivity of γ comes from the natural radionuclides of Tl-208 and K-40 are lower than 1 Bq/L for the different of three places, respectively. The metals concentration of Ngebel-lake source were Ca ≤ 14.34 ppm; Fe ≤ 0.04 ppm; Mn ≤ 0.02 ppm; Mg ≤ 6.75 ppm; Na ≤ 14.63 ppm, Ngembak source were Ca ≤ 11.6 ppm; Fe ≤ 0.04 ppm; Mn ≤ 0.02 ppm; Mg ≤ 11.13 ppm; Na ≤ 16.75 ppm and Gonggang source were Ca ≤ 13.78 ppm; Fe ≤ 0.26 ppm; Mn ≤ 0.02 ppm; Mg ≤ 6.13 ppm; Na ≤ 15.00 ppm. The water of Ngebel-lake source, Ngembak source and Gonggang source can be classified as B category water based on radioactivity and the content of the metals concentration in its. (author)

Preparation and electrical properties of Mn{sub 1.05−y}Co{sub 1.95−x−z−w}Ni{sub x}Mg{sub y}Al{sub z}Fe{sub w}O{sub 4} NTC ceramic derived from microemulsion method

Energy Technology Data Exchange (ETDEWEB)

Xia, Junbo [Key Laboratory of Functional Materials and Devices under Special Environments, CAS, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics and Chemistry, CAS, Urumqi 830011 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhao, Qing, E-mail: zhaoq@ms.xjb.ac.cn [Key Laboratory of Functional Materials and Devices under Special Environments, CAS, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics and Chemistry, CAS, Urumqi 830011 (China); Gao, Bo [Key Laboratory of Functional Materials and Devices under Special Environments, CAS, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics and Chemistry, CAS, Urumqi 830011 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Chang, Aimin, E-mail: changam@ms.xjb.ac.cn [Key Laboratory of Functional Materials and Devices under Special Environments, CAS, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics and Chemistry, CAS, Urumqi 830011 (China); Zhang, Bo; Ma, Renjun [Key Laboratory of Functional Materials and Devices under Special Environments, CAS, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics and Chemistry, CAS, Urumqi 830011 (China); University of Chinese Academy of Sciences, Beijing 100049 (China)

2014-04-05

Highlights: • The NTC thermister nano-powders Mn{sub 1.05−y}Co{sub 1.95−x−z−w}Ni{sub x}Mg{sub y}Al{sub z}Fe{sub w}O{sub 4} were prepared by microemulsion method. • The metal ions were subsided after twice sediment reaction. • The specimens show good electrical properties by doping some nontransition metals. -- Abstract: The NTC thermistor nano-powders of Mn{sub 1.05−y}Co{sub 1.95−x−z−w}Ni{sub x}Mg{sub y}Al{sub z}Fe{sub w}O{sub 4} were prepared by microemulsion method. Scanning electron microscope (SEM) image showed that the particles were well distributed. The mean particle-size was 72 nm. The structure of the precursor was investigated with Fourier infrared spectrometer (FI). The compositions of the powder and the as-sintered ceramic were evaluated by Energy Disperse Spectroscopy (EDS). X-ray diffraction (XRD) result indicated that the sintered samples were in the spinel structure. The room temperature resistivity ρ{sub 25}, material constant B{sub 25/85} and activation energies of the NTC thermistor are in the range of 1173–19,059 Ω cm, 3169–3771 k, 0.2672–0.3136 eV. The room temperature resistivity and B{sub 25/85} constant were found to increase with Al{sub 2}O{sub 3} content. The Mn{sub 0.9}Co{sub 1.2}Ni{sub 0.21}Mg{sub 0.15}Al{sub 0.09}Fe{sub 0.45}(A2) and Mn{sub 0.9}Co{sub 1.2}Ni{sub 0.27}Mg{sub 0.15}Al{sub 0.03}Fe{sub 0.45}(A3) specimens both showed a 200 °C resistance drift (ΔR/R) within 10% after aging at 910 °C for 600 h.

Sign change in the tunnel magnetoresistance of Fe3O4/MgO/Co-Fe-B magnetic tunnel junctions depending on the annealing temperature and the interface treatment

Directory of Open Access Journals (Sweden)

L. Marnitz

2015-04-01

Full Text Available Magnetite (Fe3O4 is an eligible candidate for magnetic tunnel junctions (MTJs since it shows a high spin polarization at the Fermi level as well as a high Curie temperature of 585°C. In this study, Fe3O4/MgO/Co-Fe-B MTJs were manufactured. A sign change in the TMR is observed after annealing the MTJs at temperatures between 200°C and 280°C. Our findings suggest an Mg interdiffusion from the MgO barrier into the Fe3O4 as the reason for the change of the TMR. Additionally, different treatments of the magnetite interface (argon bombardment, annealing at 200°C in oxygen atmosphere during the preparation of the MTJs have been studied regarding their effect on the performance of the MTJs. A maximum TMR of up to -12% could be observed using both argon bombardment and annealing in oxygen atmosphere, despite exposing the magnetite surface to atmospheric conditions before the deposition of the MgO barrier.

Synchrotron in-situ deformation experiments of perovskite + (Mg,Fe)O aggregates under shallow lower mantle conditions (Invited)

Science.gov (United States)

Girard, J.; Amulele, G.; Farla, R. J.; Liu, Z.; Mohiuddin, A.; Karato, S.

2013-12-01

Experimental studies on rheological properties of mantle's minerals are crucial to understand the dynamics of Earth's interior, but direct experimental studies under the relevant lower mantle conditions are challenging. Most of the earlier studies were performed at lower mantle pressures but low temperatures using DAC (diamond anvil cell) (e.g., Merkel et al., 2003)), and in DAC experiments strain-rate and stress are unknown. Some previous studies were carried out under high pressures and high temperatures (e.g, Cordier et al., 2004) , but quantitative results on rheological behaviour of said minerals were not obtained. Here we present the results of the first in-situ deformation experiments of perovskite + (Mg,Fe)O (Pv + fp) aggregates using RDA (rotational Drickamer apparatus). The RDA has a better support for the anvils at high pressure than the more commonly used D-DIA apparatus and hence we can reach higher pressures and temperatures than the D-DIA. We have recently made new modifications to the cell assembly to reach the lower mantle conditions with less interference in X-ray diffraction patterns by the surrounding materials. The starting material was ringwoodite synthesized using a multi-anvil. In-situ deformation experiments were then carried at pressure up to 28 GPa (calculated from thermal EOS of Pt) and estimated temperatures up to 2200 K using RDA. Under these conditions, ringwoodite transformed to Pv + fp. We subsequently deformed the sample between strain rates of 10-4 to 10-5 s-1. Stress and strain were measured in-situ using X-ray synchrotron beam. The recovered sample analyses show evidence of perovskite+(Mg,Fe)O microstructure (Fig. 1). The radial X-ray diffraction data are being analysed to determine the stress levels of two minerals. Also microstructures of deformed specimens are studied to understand the deformation mechanisms and strain partitioning. The results will contribute towards our understanding of the rheological properties of the

Large enhancement of Blocking temperature by control of interfacial structures in Pt/NiFe/IrMn/MgO/Pt multilayers

Directory of Open Access Journals (Sweden)

Xi Chen

2015-09-01

Full Text Available The Blocking temperature (TB of Pt/NiFe/IrMn/MgO/Pt multilayers was greatly enhanced from far below room temperature (RT to above RT by inserting 1 nm thick Mg layer at IrMn/MgO interface. Furthermore, the exchange bias field (Heb was increased as well by the control of interfacial structures. The evidence for a significant fraction of Mn-O bonding at IrMn/MgO interface without Mg insertion layer was provided by X-ray photoelectron spectroscopy. The bonding between Mn and O can decrease the antiferromagnetism of IrMn film, leading to lower value of TB in Pt/NiFe/IrMn/MgO/Pt multilayers. Ultrathin Mg film inserted at IrMn/MgO interface acting as an oxygen sinking layer can suppress the oxidation reactions between Mn and O and reduce the formation of Mn-O bonding greatly. The oxidation suppression results in the recovery of the antiferromagnetism of IrMn film, which can enhance TB and Heb. Furthermore, the high resolution transmission electron microscopy demonstrates that the Mg insertion layer can efficiently promote a high-quality MgO (200 texture. This study will enhance the understanding of physics in antiferromagnet-based spintronic devices.

Enhancement of the critical current density in FeO-coated MgB2 thin films at high magnetic fields

Directory of Open Access Journals (Sweden)

Andrei E. Surdu

2011-12-01

Full Text Available The effect of depositing FeO nanoparticles with a diameter of 10 nm onto the surface of MgB2 thin films on the critical current density was studied in comparison with the case of uncoated MgB2 thin films. We calculated the superconducting critical current densities (Jc from the magnetization hysteresis (M–H curves for both sets of samples and found that the Jc value of FeO-coated films is higher at all fields and temperatures than the Jc value for uncoated films, and that it decreases to ~105 A/cm2 at B = 1 T and T = 20 K and remains approximately constant at higher fields up to 7 T.

Enhanced vibronic interaction caused by local lattice symmetry lowering in the (Fe, Mg)As2 ternary system

Science.gov (United States)

Pishtshev, A.; Rubin, P.

2018-04-01

By means of periodic density functional theory (DFT) electronic structure calculations, we investigate iron-site doping effects in a structural model of bulk FeAs2. Simulations performed within the projector augmented-wave method-Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) functional scheme reveal that the impacts of the two stoichiometric substitutions Fe → Mg and Fe → Ni are radically different with respect to the structural and electronic behavior of the dopants. In particular, unlike the Ni dopant, the Mg dopant incorporated in FeAs2 occupies a noncentral equilibrium position characterized by an off-center displacement from the reference higher-symmetry position. Analysis of the respective electron and vibrational factors allows us to explain this result in terms of the local pseudo Jahn-Teller effect (pJTE). On the basis of DFT calculations, we deduce which electron orbitals and lattice vibrational modes are appropriate for promoting the local instability at the origin of the pJTE. Quantitative evaluations of the pJTE parameters performed within the polyatomic formalism of an effective tight-binding model show that it is just the enhanced vibronic interaction in the Mg-[FeAs6] cluster that is responsible for the local lattice symmetry breaking.

Improved (0 0 1)-texture of FePt-C for heat-assisted magnetic recording media by insertion of Cr buffer layer

Energy Technology Data Exchange (ETDEWEB)

Shiroyama, T.; Wang, J.; Felicia, A.; Takahashi, Y.K.; Hono, K., E-mail: kazuhiro.hono@nims.go.jp

2017-06-15

Highlights: • Improvement of (0 0 1)-texture of prototype FePt-C granular films for heat heat assisted magnetic recording media. • Insertion of Cr buffer layer improves the crystallographic textures of the MgO underlayers, thereby reduces in-plane component in the FePt-C recording layer. • The growth in the grain size of the MgO underlayer as well as the (0 0 1)-texture of the MgO underlayer are the key factor in reducing the in-plane component in the FePt-C recording layer. - Abstract: FePt-C granular films deposited on MgO underlayers are the prototype media for heat-assisted magnetic recording. To reduce the in-plane magnetic component in the FePt-C media, we investigated the effect of Cr buffer layers on the crystallographic textures of the MgO underlayers and the resultant magnetic properties of the FePt-C layers. By growing a MgO underlayer on a Cr buffer layer, the (0 0 1) texture of the MgO underlayer is improved, on which the in-plane component of a FePt-C film is substantially reduced. We conclude that the growth in the grain size of the MgO underlayer is the key factor in reducing the in-plane component in the FePt-C recording layer.

Effect of Porous Structure on the Magnetic Properties of NixMgyZn1−x−yFe2O4 Magnetic Materials

International Nuclear Information System (INIS)

Qi Xin; Zhou Xin; Shu Di; Zhao Jing-Jing; Wang Wei; Chen Juan

2011-01-01

We deal with the preparation of NiMgZnFe III -SO 4 layered double hydroxides (LDHs) with the layered precursor method and introduce excessive ZnO into the NiMgZnFe III -SO 4 LDHs to produce Ni x Mg y Zn 1−x−y Fe 2 O 4 ferrites that contain massive ZnO. Then the Ni x Mg y Zn 1−x−y Fe 2 O 4 ferrites are treated with NaOH solution to remove ZnO to produce the porous Ni x Mg y Zn 1−x−y Fe 2 O 4 magnetic material: when y = 0, porous NiZnFe 2 O 4 ferrite magnetic materials are obtained; when y ≠ 0, porous NiMgZnFe 2 O 4 ferrite magnetic materials are obtained. From analyses of these two ferrites, their pore-forming mechanism and comparison of their properties before and after they undergo the alkali treatment, we find that after being treated by the NaOH solution, NiZnFe 2 O 4 /NiMgZnFe 2 O 4 have better uniform-structure pores, which will greatly expand their pore volume, widen their application scope and improve their magnetic properties. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Disorder- and correlation-induced charge carriers localization in oxyborate MgFeBO{sub 4}, Mg{sub 0.5}Co{sub 0.5}FeBO{sub 4}, CoFeBO{sub 4} single crystals

Energy Technology Data Exchange (ETDEWEB)

Knyazev, Yu.V. [Siberian Federal University, 660074 Krasnoyarsk (Russian Federation); Kazak, N.V., E-mail: nat@iph.krasn.ru [Kirensky Institute of Physics, 660036 Krasnoyarsk (Russian Federation); Platunov, M.S. [Kirensky Institute of Physics, 660036 Krasnoyarsk (Russian Federation); Ivanova, N.B. [Siberian Federal University, 660074 Krasnoyarsk (Russian Federation); Bezmaternykh, L.N. [Kirensky Institute of Physics, 660036 Krasnoyarsk (Russian Federation); Arauzo, A. [Servicio de Medidas Físicas, Universidad de Zaragoza, 50009 Zaragoza (Spain); Bartolomé, J. [Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza and Departamento de Física de la Materia Condensada, 50009 Zaragoza (Spain); Ovchinnikov, S.G. [Siberian Federal University, 660074 Krasnoyarsk (Russian Federation); Kirensky Institute of Physics, 660036 Krasnoyarsk (Russian Federation); Siberian State Aerospace University, 660014 Krasnoyarsk (Russian Federation)

2015-09-05

Highlights: • The electrical resistance of the single crystalline warwickites has been measured. • The temperature-induced changes in the charge transfer mechanisms have been found. • The microscopic parameters of the electronic structure have been determined. • The studied warwickites have been classified as disordered correlated systems. • The Co substitution was found to lead to the weakening of the localization. - Abstract: The temperature dependence of the resistivity of single crystalline Mg{sub 1−x}Co{sub x}FeBO{sub 4} samples with x = 0.0, 0.5, 1.0 is investigated for the temperature range (210–400 K). The conduction was found to be governed by Mott variable-range hopping (VRH) in the low-temperature range (T = 210–270 K) and by thermo-activation mechanism in the high-temperature range (T = 280–400 K). Microscopic electronic parameters, such as the density of the localized states near the Fermi level, localization length, the hopping length, and the activation energy have been obtained. The change of the activation energy observed at high-temperature range was attributed to local structure distortions around Fe and Co atoms. The complicated behavior of charge transfer mechanisms is discussed based on two approaches: atomic disorder and electron correlations.

Industrial contamination of soil related to some active and closed mine facilities in the Republic of Macedonia

Directory of Open Access Journals (Sweden)

Tasev Goran K.

2015-01-01

Full Text Available Several industrial pollution sources at the territory of the Republic of Macedonia, were studied, one Pb-Zn mine with mill, one copper mine with mill and copper leaching facility, as well as one former Pb-Zn smelting facility near the city of Veles and one Fe-Ni smelting facility near the city of Kavadarci. The concentrations of heavy metals at Veles hot-spot were in the range: 20÷1823 mg kg- 1Pb, 29÷2395 mg kg-1Zn, 28÷65 mgkg-1Cd, 27÷82 mg kg-1 Cu, 39÷164 mg kg-1Ni, 508÷938 mgkg-1Mn and 1.6÷3.8% Fe, all of them being above Dutch standard optimal values. The vicinity of the Feni plant displayed concentrations of heavy metals as follows: 16÷31 mg kg-1 Pb, 117÷286 mgkg-1 Zn, 13÷24 mg kg-1Co, 42÷119 mg kg-1 Cu, 158÷292 mg kg-1Ni, 119÷236 mg kg-1 Cr and 2.24÷3.79% Fe. Airborne dust measurements around the Zletovo mine displayed multiplexed above standard values, with an exception of nickel, there enrichment factors ranged from mediate ones such were those for copper of 20.8, cadmium of 28.7, arsenic of 32.5 up to high ones for zinc with 341.7 and lead 925. Soil samples around the Zletovo mine displayed: 19.3-76.9 g kg-1 Fe, 643-28000 mg kg-1 Mn, 42.3-529.66 mg kg-1 Pb and 138-3240 mg kg-1 Zn. Finally around the Bucim copper mine the results displayed the following findings: 13.1÷225 mg kg-1 As, 0.67÷17.9 mg kg-1 Cd, 30.1÷171 mg kg-1 Cr, 17.8÷1734 mg kg-1 Cu, 9.8÷69.4 mg kg-1 Ni, 46÷3456 mg kg-1 Pb, 88÷3438 mg kg-1 Zn, 169÷998 mg kg-1 Mn, 0.73÷5.02% Fe.

Trapped magnetic field in a (NdFeB)–(MgB2) pair-type bulk magnet

International Nuclear Information System (INIS)

Aldica, Gheorghe; Burdusel, Mihail; Badica, Petre

2014-01-01

Highlights: • Dense MgB 2 discs were obtained by ex-situ Spark Plasma Sintering. • A NdFeB–MgB 2 pair-type bulk magnet was tested for different working conditions. • The polarity of the NdFeB permanent magnet influences macro flux jumps of MgB 2 . • Trapped field of the pair was 2.45 T (20 K) and 3.3 T (12 K). - Abstract: Superconducting bulk discs, S, of 20 mm in diameter and 3.5 or 3.3 mm thickness of MgB 2 (pristine or added with cubic BN, respectively) with density above 97% were prepared by Spark Plasma Sintering. Discs were combined in a pair-type sandwich-like arrangement with a permanent NdFeB axially magnetised magnet, PM (∼0.5 T). Measurement of the trapped field, B tr , with temperature, time, and the reduction rate of the applied magnetic field was performed using a Hall sensor positioned at the centre between the superconductor and the permanent magnet. It is shown that the permanent magnet with certain polarity favors higher trapped field of the superconductor owing to suppression of flux jumps specific for high density MgB 2 samples. The B tr of the PM–S pair was 2.45 T (20 K) and 3.3 T (12 K)

Sol-gel route of synthesis of nanoparticles of MgFe2O4 and XRD, FTIR and VSM study

International Nuclear Information System (INIS)

Pradeep, A.; Priyadharsini, P.; Chandrasekaran, G.

2008-01-01

Nanoparticles of MgFe 2 O 4 are synthesized using sol-gel autocombustion method. Structural studies are carried out using X-ray diffraction (XRD). The XRD pattern of MgFe 2 O 4 provides information about single-phase formation of spinel structure with cubic symmetry. The grain size and lattice constant are obtained using XRD data. The cation distribution is also proposed theoretically. The change in site preference of cations in nano-MgFe 2 O 4 is compared with its bulk counterpart. The structural morphology of the nanoparticles is studied using Scanning Electron Microscopy (SEM). Formation of spinel structure is conformed using Fourier transform infrared spectroscopy (FTIR), which also lends support for the cation distribution proposed using XRD data. The effect of nanoregime on parameters such as bond length, vibration frequency and force constant are discussed with the help of FTIR data. The M-H loop of MgFe 2 O 4 has been traced using the Vibrating Sample Magnetometer (VSM) and magnetic parameters such as saturation magnetization (M S ), coercivity (H C ) and retentivity (M R ) are obtained from VSM data

Ni/Fe and Mg/Fe layered double hydroxides and their calcined derivatives: preparation, characterization and application on textile dyes removal

Directory of Open Access Journals (Sweden)

Rachid Elmoubarki

2017-07-01

Full Text Available In this study, Mg/Fe and Ni/Fe layered double hydroxides (LDHs with molar ratio (M2+/Fe3+ of 3 and intercalated with carbonate ions were synthesized by co-precipitation method. The as-synthesized materials and their calcined products (CLDHs were characterized by X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FT-IR, thermo-gravimetric and differential thermal analyses (TGA–DTA, transmission electron microscopy coupled with energy dispersive X-ray spectroscopy (TEM-EDX, inductively coupled plasma (ICP and elemental chemical analysis CHNSO. The materials were used as adsorbents for the removal availability of textile dyes from aqueous solution. Methylene blue (MB and malachite green (MG, representative of cationic dyes, and methyl orange (MO representative of anionic dyes were used as model molecules. Adsorption experiments were carried out under different parameters such as contact time, temperature, initial dyes concentration and solution pH. Experimental results indicate that CLDHs had much higher adsorption capacities compared to LDHs. Adsorption kinetic data fitted well the pseudo-second order kinetic model. The process was spontaneous, endothermic for cationic dyes and exothermic for the anionic dye. Equilibrium sorption data fitted the Langmuir model instead of Freundlich model.

Texture gradients in Fe-sheathed ex situ produced MgB2 tapes

International Nuclear Information System (INIS)

Lezza, P; Gladyshevskii, R; Abaecherli, V; Fluekiger, R

2006-01-01

Superconducting Fe-sheathed MgB 2 monofilamentary tapes have been fabricated by the powder-in-tube technique, varying the particle size of the starting MgB 2 powder and applying either cold or hot rolling during the last deformation process. Measurements of the critical current density J c with the magnetic field applied parallel or perpendicular to the tape surface revealed a pronounced anisotropy for the cold rolled tapes, which was found to increase with increasing particle size and magnetic field strength. The microstructural origin of the J c anisotropy was confirmed by means of x-ray diffraction performed on the filaments after mechanical removal of the sheath. The local texture was studied in a series of diffraction patterns collected at different distances from the filament centre, removing each time some 25 μm of the filament thickness. In the cold rolled tapes, the average orientation of the MgB 2 grains was found to approach a preferred orientation with the crystallographic c-axis perpendicular to the tape surface, near the interface with the sheath; however, the misalignment angle increased towards the centre of the tape. In the hot rolled tapes, for which no J c anisotropy was observed, the grains were found to be approximately randomly oriented. Roughness measurements performed on the side of the Fe sheath in contact with the MgB 2 filament are in agreement with the difference in texture observed for cold and hot rolled tapes

Photocatalytic degradation of RhB over MgFe2O4/TiO2 composite materials

International Nuclear Information System (INIS)

Zhang Lei; He, Yiming; Wu Ying; Wu Tinghua

2011-01-01

Highlights: → Novel composite MgFe 2 O 4 /TiO 2 as catalyst. → Higher activity for the photodegradation of RhB under visible light irradiation. → Calcination temperature of catalyst has effect on photocatalytic activity. → Different photocatalysis mechanism under UV and visible light irradiation. - Abstract: MgFe 2 O 4 /TiO 2 (MFO/TiO 2 ) composite photocatalysts were successfully synthesized using a mixing-annealing method. The synthesized composites exhibited significantly higher photocatalytic activity than a naked semiconductor in the photodegradation of Rhodamine B. Under UV and visible light irradiation, the optimal percentages of doped MgFe 2 O 4 (MFO) were 2 wt.% and 3 wt.%, respectively. The effects of calcination temperature on photocatalytic activity were also investigated. The origin of the high level of activity was discussed based on the results of X-ray diffraction, UV-vis diffuse reflection spectroscopy, scanning electron microscopy, transmission electron microscopy, and nitrogen physical adsorption. The enhanced activity of the catalysts was mainly attributed to the synergetic effect between the two semiconductors, the band potential of which matched suitably.

Simple synthesis of graphene nanocomposites MgO-rGO and Fe2O3-rGO for multifunctional applications

Science.gov (United States)

Abdel-Aal, Seham K.; Ionov, Andrey; Mozhchil, R. N.; Naqvi, Alim H.

2018-05-01

Hummer's method was used to prepare graphene oxide (GO) by chemical exfoliation of graphite. Simple precipitation method was used for the preparation of hybrid nanocomposites MgO-rGO and Fe2O3-rGO. A 0.3 Molar of corresponding metal nitrate solution and GO solution are used for the preparation process. XRD, FT-IR, and XPS were used to characterize the prepared nanocomposites. The reduction of GO into reduced rGO in the formed nanocomposites was confirmed. Morphological characterization showed the formation of needle-shaped nanocrystals of MgO successfully grown on graphene nanosheet with average crystallite size 8.4 nm. Hematite nanocomposite Fe2O3-rGO forms rod-shaped crystals with average crystallite size 27.5 nm. The saturation magnetization observed for Fe2O3-rGO is less than reported value for the pure Fe2O3 nanoparticles. Thermal properties of as-prepared hybrid nanocomposites MgO-rGO and Fe2O3-rGO showed thermal stability of the prepared nanocomposite over long range of temperature.

Perpendicular magnetic anisotropy in Mo/Co2FeAl0.5Si0.5/MgO/Mo multilayers with optimal Mo buffer layer thickness

Science.gov (United States)

Saravanan, L.; Raja, M. Manivel; Prabhu, D.; Pandiyarasan, V.; Ikeda, H.; Therese, H. A.

2018-05-01

Perpendicular Magnetic Anisotropy (PMA) was realized in as-deposited Mo(10)/Co2FeAl0.5Si0.5(CFAS)(3)/MgO(0.5)/Mo multilayer stacks with large perpendicular magnetic anisotropy energy (Keff). PMA of this multilayer is found to be strongly dependent on the thickness of the individual CFAS (tCFAS), Mo (tMo) and MgO (tMgO) layers and annealing temperatures. The interactions at the Mo/CFAS/MgO interfaces are critical to induce PMA and are tuned by the interfacial oxidation. The major contribution to PMA is due to iron oxide at the CFAS/MgO interface. X-ray diffraction (XRD) and infrared spectroscopic (FT-IR) studies further ascertain this. However, an adequate oxidation of MgO and the formation of (0 2 4) and (0 1 8) planes of α-Fe2O3 at the optimal Mo buffer layer thickness is mainly inducing PMA in Mo/CFAS/MgO/Mo stack. Microstructural changes in the films are observed by atomic force microscopy (AFM). X-ray photoelectron spectroscopy (XPS) demonstrates the oxidation of CFAS/MgO interface and the formation of Fe-O bonds confirming that the real origin of PMA in Mo/CFAS/MgO is due to hybridization of Fe (3dz2) and O (2pz) orbitals and the resulted spin-orbit interaction at their interface. The half-metallic nature CFAS with Mo layer exhibiting PMA can be a potential candidate as p-MTJs electrodes for the new generation spintronic devices.

Tunnel magnetoresistance in thermally robust Mo/CoFeB/MgO tunnel junction with perpendicular magnetic anisotropy

Directory of Open Access Journals (Sweden)

B. Fang

2015-06-01

Full Text Available We report on tunnel magnetoresistance and electric-field effect in the Mo buffered and capped CoFeB/MgO magnetic tunnel junctions (MTJs with perpendicular magnetic anisotropy. A large tunnel magnetoresistance of 120% is achieved. Furthermore, this structure shows greatly improved thermal stability and stronger electric-field-induced modulation effect in comparison with the Ta/CoFeB/MgO-based MTJs. These results suggest that the Mo-based MTJs are more desirable for next generation spintronic devices.

FeII/MgII Emission Line Ratio in High Redshift Quasars

DEFF Research Database (Denmark)

Dietrich, M.; Hamann, F.; Appenzeller, I.

2003-01-01

the evolution of the FeII/MgII ratio over a wider range in cosmic time, we measured this ratio for composite quasar spectra which cover a redshift range of 0 4 quasars must have started already at an epoch corresponding to z_f = 6 to 9, when the age of the universe was ~0.5 Gyr (H_o = 72 km/s/Mpc, Omega_M = 0...

Variation of heavy metal and micro and macro element concentrations of bread and durum wheats and their relationship in grain of Turkish wheat cultivars.

Science.gov (United States)

Harmankaya, Mustafa; Ozcan, Mehmet Musa; Gezgin, Sait

2012-09-01

The 64 varieties displayed a large variation for all mineral elements, investigated Fe, Mn and Zn, ranging from 24.2 to 43.1 mg/kg, 27.6 to 64.8 mg/kg and 10.4 to 38.2 mg/kg, respectively. The mean Ca, K, Mg, Na, P and S concentrations in wheat rain varieties amounted to 378, 4,266, 1,183, 317, 3,513 and 1,542 mg/kg, respectively. Ca, K, Mg, Na, P and S contents of wheat varieties changed at the levels between 266 and 531 mg/kg, 3,029 and 5,566 mg/kg, 972 and 1,525 mg/kg, 277 and 368 mg/kg, 2,422 and 4,610 mg/kg and 1,241 to 2,052 mg/kg, respectively. The concentrations of Al, Cu, Fe, Mn and Zn of durum wheat samples were found at high levels. The mean Al, Cr, Mo, Ni, Cu, Fe, Mn and Zn concentrations in durum wheat varieties amounted to 10.93, 0.47, 0.72, 0.72, 5.37, 34.9, 37.28 and 20.88 mg/kg, respectively.

Optical absorption and thermoluminescence in Mg O, Mg O:Ni and Mg O:Li irradiated at room temperature; Absorcion optica y termoluminiscencia en MgO, MgO:Ni y MgO:Li irradiados a temperatura ambiente

Energy Technology Data Exchange (ETDEWEB)

Delgado, L

1984-07-01

Optical absorption and thermoluminescence (TL) studies in Mg O, Mg O:Ni and Mg O:Li irradiated at room temperature are presented. In pure Mg O the thermal annihilation of Fe3+ by recombination with thermally released electrons at {approx} 90 and 175 degree centigree and the V center annealing by hole release up to 100 degree centigree cause the observed glow peaks at these temperatures. The TL excitation spectrum shows two maxima at 245 nm (electron center) and 288 nm (Fe3+). In Mg O:Ni X irradiation induces Fe{sup 2}+ {yields}- Fe{sup 3}+ and Ni{sup 2}+ {yields} Ni{sup 3}+ oxidations. Two TL emission bands centered at 110 degree centigree (red) and 80 o{sup C} (green) are assigned to electron release and their recombination at Fe{sup 3}+ and Ni{sup 3}+ respectively. In Mg O:Li two TL emission bands, one blue (430 nm) and the other red (730 nm) with excitation maxima at 245 nm (electron center) and 200 nm (hole center) respectively are observed. No V-center formation was detected in both Ni and Li doped samples. (Author) 42 refs.

Magnetic properties and magnetocaloric effects in Mn1.2Fe0.8P1-xGex compounds

International Nuclear Information System (INIS)

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

2006-01-01

We have studied the magnetic properties and magnetocaloric effects in the Mn 1.2 Fe 0.8 P 1-x Ge x compounds with x = 0.2, 0.22, 0.3, 0.4 and 0.5. X-ray diffraction patterns show that the Mn 1.2 Fe 0.8 P 1-x Ge x compounds crystallize in the hexagonal Fe 2 P-type crystal structure. The magnetic moments of the Mn 1.2 Fe 0.8 P 1-x Ge x compounds measured at 5 K and 5 T increase with increasing Ge content. The Curie temperature increases strongly and the magnetic entropy change has a maximum around 233 K for the compound with x = 0.22, which is about 19 and 31 J kg -1 K -1 for a field change of 2 and 5 T, respectively

Magnetoelectric effect in nanogranular FeCo-MgF films at GHz frequencies

Science.gov (United States)

Ikeda, Kenji; Kobayashi, Nobukiyo; Arai, Ken-Ichi; Yabukami, Shin

2018-01-01

The magnetoelectric effect is a key issue for material science and is particularly significant in the high frequency band, where it is indispensable in industrial applications. Here, we present for the first time, a study of the high frequency tunneling magneto-dielectric (TMD) effect in nanogranular FeCo-MgF films, consisting of nanometer-sized magnetic FeCo granules dispersed in an MgF insulator matrix. Dielectric relaxation and the TMD effect are confirmed at frequencies over 10 MHz. The frequency dependence of dielectric relaxation is described by the Debye-Fröhlich model, taking relaxation time dispersion into account, which reflects variations in the nature of the microstructure, such as granule size, and the inter-spacing between the granules that affect the dielectric response. The TMD effect reaches a maximum at a frequency that is equivalent to the inverse of the relaxation time. The frequency where the peak TMD effect is observed varies between 12 MHz and 220 MHz, depending on the concentration of magnetic metal in the nanogranular films. The inter-spacing of the films decreases with increasing magnetic metal concentration, in accordance with the relaxation time. These results indicate that dielectric relaxation is controlled by changing the nanostructure, using the deposition conditions. A prospective application of these nanogranular films is in tunable impedance devices for next-generation mobile communication systems, at frequencies over 1 GHz, where capacitance is controlled using the applied magnetic field.

Pile oscillator measurements of thermal absorption cross sections of Al, Mg, Fe and Cu

International Nuclear Information System (INIS)

Carre, J.C.; Vidal, R.

1964-01-01

The phase oscillation technique used at ZOE has the property of reducing of a marked factor the effect of neutron scattering by the sample. The absorption cross sections of poorly absorbing and highly scattering materials have been measured; for neutrons of 2,200 m/s, the following values are obtained: 229 ± 3 mb for Al; 64.2 ± 1.5 mb for Mg, 2.53 ± 0.03 b for Fe and 3.74 ± 0.04 b for Cu. (authors) [fr

Solvothermal synthesis of Mg-doped Li2FeSiO4/C nanocomposite cathode materials for lithium-ion batteries

Science.gov (United States)

Kumar, Ajay; Jayakumar, O. D.; Naik, V. M.; Nazri, G. A.; Naik, R.

Lithium transition metal orthosilicates, such as Li2FeSiO4 and Li2MnSiO4, as cathode material have attracted much attention lately due to their high theoretical capacity ( 330 mAh/g), low cost, and environmental friendliness. However, they suffer from poor electronic conductivity and slow lithium ion diffusion in the solid phase. Several cation-doped orthosilicates have been studied to improve their electrochemical performance. We have synthesized partially Mg-substituted Li2Mgx Fe1-x SiO4-C, (x = 0.0, 0.01, 0.02, and 0.04) nano-composites by solvothermal method followed by annealing at 600oC in argon flow. The structure and morphology of the composites were characterized by XRD, SEM and TEM. The surface area and pore size distribution were measured by using N2 adsorption/desorption curves. The electrochemical performance of the Li2MgxFe1-x SiO4-C composites was evaluated by Galvanostatic cycling against metallic lithium anode, electrochemical impedance spectroscopy, and cyclic voltammetry. Li2Mg0.01Fe0.99SiO4-C sample shows a capacity of 278 mAh/g (at C/30 rate in the 1.5-4.6 V voltage window) with an excellent rate capability and stability, compared to the other samples. We attribute this observation to its higher surface area, enhanced electronic conductivity and higher lithium ion diffusion coefficient.

Study on the water durability of zinc boro-phosphate glasses doped with MgO, Fe2O3, and TiO2

Science.gov (United States)

Hwang, Moon Kyung; Ryu, Bong Ki

2016-07-01

The water durability of zinc boro-phosphate (PZB) glasses with the composition 60P2O5-20ZnO-20B2O3- xMeO ( x = 0, 2, 4, 6 and MeO = MgO, Fe2O3, or TiO2) (mol%) was measured, and PZB glass was studied in terms of its thermal properties, density, and FTIR characteristics. The surface conditions and corrosion byproducts were analyzed using scanning electron microscopy. When MgO, Fe2O3, and TiO2 were doped into the PZB glass, Q2 was decreased and Q1 was increased in the phosphate structure, while the number of BO4 structures increased with increasing MeO content. The density of the PZB glass was increased by the addition of Fe2O3 and TiO2, while the glass transition temperature ( T g ) and dilatometric softening temperature ( T d ) were increased when additional MgO, Fe2O3, and TiO2 were added. From the weight loss analysis (95 ◦ C, 96 h), TiO2 doped glass showed the lowest weight loss (1.70 × 10 -3 g/cm2) while MgO doped glass showed the highest value (2.44 × 10 -3 g/cm2), compared with PZB glass (3.07 × 10 -3 g/cm2). These results were discussed in terms of the Me n+ ions in the glass structure, and their different coordination numbers and bonding strengths.

Comparative study on catalytic behavior of polynuclear Mg-Mo-complex and FeMo-co-factor of nitrogenase in reactions with C2H2, N2 and CO

International Nuclear Information System (INIS)

Bardina, N.V.; Bazhenova, T.A.; Petrova, G.N.; Shilova, A.K.; Shilov, A.E.

2006-01-01

Catalytic reduction kinetics of C 2 H 2 in the presence of the Mg-Mo-cluster {[Mg 2 Mo 8 O 22 (MeO) 6 (MeOH) 4 ] 2- [Mg(MeOH) 6 ] 2+ }·6MeOH 1 is studied. Several interdependent coordinating centers are active in reference to substrates and inhibitors in the polynuclear Mg-Mo-complex, as in the reduced by europium amalgam (μ 6 -N)MoFe 7 S 9 ·homocitrate (FeMoco, 2). Comparison of regularities in reduction mechanism of C 2 H 2 , N 2 and CO with the participation of synthetic polynuclear complex 1 and natural cluster 2 is conducted. Regularities of the studied reactions in the systems involving natural catalytic cluster FeMoco and the synthetic Mg-Mo-complex modelling of its effect are noted to be similar. The main variations the systems show as regards to the reaction with molecular nitrogen [ru

Sono-chemical Synthesis Fe3O4-Mg(OH2 Nanocomposite and Its Photo-catalyst Investigation in Methyl Orange Degradation

Directory of Open Access Journals (Sweden)

G. Nabiyouni

2014-10-01

Full Text Available In this work firstly Fe3O4 nanoparticles were synthesized via a sono-chemical method. At the second step magnesium hydroxide shell was synthesized on the magnetite-core under ultrasonic waves. For preparation Fe3O4-MgO the product was calcinated at 400 ºC for 2h. Properties of the product were examined by X-ray diffraction pattern (XRD, scanning electron microscope (SEM and Fourier transform infrared (FT-IR spectroscopy. Vibrating sample magnetometer (VSM shows nanoparticles exhibit super-paramagnetic behavior. The photo-catalytic behavior of Fe3O4-Mg(OH2  nanocomposite was evaluated using the degradation of a methyl orange (MeO aqueous solution under ultraviolet (UV light irradiation. The results show that Fe3O4-Mg(OH2 nanocomposites have applicable magnetic and photo-catalytic performance.

Lower-temperature crystallization of CoFeB in MgO magnetic tunnel junctions by using Ti capping layer

International Nuclear Information System (INIS)

Ibusuki, Takahiro; Miyajima, Toyoo; Umehara, Shinjiro; Eguchi, Shin; Sato, Masashige

2009-01-01

Effects of capping materials on magnetoresistance (MR) properties of MgO magnetic tunnel junctions (MTJs) with a CoFeB free layer were investigated. MR ratios of samples with various capping materials showed a difference in annealing temperature dependence. MTJ with a Ti capping layer annealed at 270 deg. C showed a MR ratio 1.4 times greater than that with a conventional Ta or Ru capping layer. Secondary ion mass spectroscopy and high-resolution transmission electron microscopy images revealed that crystallization of CoFeB was remarkably affected by adjacent materials and the Ti capping layer adjoining CoFeB acted as a boron-absorption layer. These results suggest that the crystallization process can be controlled by choosing proper capping materials. Ti is one of the effective materials that accelerate the crystallization of CoFeB layers at lower annealing temperature

Cation distribution and crystallographic characterization of the spinel oxides MgCr{sub x}Fe{sub 2−x}O{sub 4} by neutron diffraction

Energy Technology Data Exchange (ETDEWEB)

Zakaria, A.K.M., E-mail: zakaria6403@yahoo.com [Institute of Nuclear Science & Technology, Bangladesh Atomic Energy Commission, Dhaka (Bangladesh); Nesa, Faizun [Department of Natural Science, Daffodil International University, Dhaka (Bangladesh); Department of Physics, Jahangirnagar University, Savar, Dhaka (Bangladesh); Saeed Khan, M.A. [Department of Physics, Jahangirnagar University, Savar, Dhaka (Bangladesh); Datta, T.K.; Aktar, Sanjida; Liba, Samia Islam; Hossain, Shahzad; Das, A.K.; Kamal, I.; Yunus, S.M. [Institute of Nuclear Science & Technology, Bangladesh Atomic Energy Commission, Dhaka (Bangladesh); Eriksson, S.-G. [Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg (Sweden)

2015-06-05

Highlights: • MgCr{sub x}Fe{sub 2−x}O{sub 4} ferrites crystallize at 1300 °C and possess cubic symmetry. • Cation distribution and crystallographic parameters have been determined precisely. • Cell parameter decreases with increasing Cr content in the system. • Ferrimagnetic ordering was found at room temperature for all the samples. - Abstract: The spinel system MgCr{sub x}Fe{sub 2−x}O{sub 4} (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) has been prepared by solid state sintering method in air at 1573 K. X-ray and neutron powder diffraction experiments have been performed on the samples at room temperature for structural characterization. Rietveld refinement of the neutron diffraction data reveals that all the samples of the series possess cubic symmetry corresponding to the space group F d-3m. The distribution of the three cations Mg, Fe and Cr over the two sublattices and other crystallographic parameters has been determined precisely. The results reveal that Cr has been substituted for Fe selectively. Cr ions invariably occupy the octahedral (B) site for all values of x. Mg and Fe ions are distributed over both A and B sites for all x values. With increasing x the occupation of Mg increases in the A site and decreases in the B site for all the samples, while the Fe ions gradually decreases in both the sites for all values of x. The lattice constant decreases with increasing Cr content in the system. The magnetic structure at room temperature was ferrimagnetic for all the samples.

Effect of Fe substitution on magnetocaloric effect in La{sub 0.7}Sr{sub 0.3}Mn{sub 1-x}Fe{sub x}O{sub 3} (0.05{<=}x{<=}0.20)

Energy Technology Data Exchange (ETDEWEB)

Barik, S K; Krishnamoorthi, C [Department of Physics and NUS Nanoscience and Nanotechnology Initiative, 2 Science Drive 3, National University of Singapore, Singapore 117542, Singapore. (Singapore); Mahendiran, R [Department of Physics and NUS Nanoscience and Nanotechnology Initiative, 2 Science Drive 3, National University of Singapore, Singapore 117542, Singapore. (Singapore)

2011-04-15

We have studied the effect of Fe substitution on magnetic and magnetocaloric properties in La{sub 0.7}Sr{sub 0.3}Mn{sub 1-x}Fe{sub x}O{sub 3} (x=0.05, 0.07, 0.10, 0.15, and 0.20) over a wide temperature range (T=10-400 K). It is shown that substitution by Fe gradually decreases the ferromagnetic Curie temperature (T{sub C}) and saturation magnetization up to x=0.15 but a dramatic change occurs for x=0.2. The x=0.2 sample can be considered as a phase separated compound in which both short-range ordered ferromagnetic and antiferromagnetic phases coexist. The magnetic entropy change (-{Delta}S{sub m}) was estimated from isothermal magnetization curves and it decreases with increase of Fe content from 4.4 J kg{sup -1} K{sup -1} at 343 K (x=0.05) to 1.3 J kg{sup -1} K{sup -1} at 105 K (x=0.2), under {Delta}H=5 T. The La{sub 0.7}Sr{sub 0.3}Mn{sub 0.93}Fe{sub 0.07}O{sub 3} sample shows negligible hysteresis loss, operating temperature range over 60 K around room temperature with refrigerant capacity of 225 J kg{sup -1}, and magnetic entropy of 4 J kg{sup -1} K{sup -1} which will be an interesting compound for application in room temperature refrigeration. - Research highlights: > We report magnetocaloric effect in La{sub 0.7}Sr{sub 0.3}Mn{sub 1-x}Fe{sub x}O{sub 3} (x=0-0.2). > Magnetic entropy change ({Delta}S{sub m}) decreases with increasing x. > A large {Delta}S{sub m} and refrigeration capacity are found around 300 K in x=0.07.

Characteristics and corrosion studies of vanadate conversion coating formed on Mg-14 wt%Li-1 wt%Al-0.1 wt%Ce alloy

Energy Technology Data Exchange (ETDEWEB)

Ma Yibin [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Li Ning, E-mail: lininghit@263.net [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Li Deyu [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Zhang Milin; Huang Xiaomei [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, Harbin Engineering University, Harbin 150001 (China)

2012-11-15

Highlights: Black-Right-Pointing-Pointer Vanadate film forms on the surface of Mg-Li-Al-Ce alloy. Black-Right-Pointing-Pointer Vanadate coating improves the corrosion resistance. Black-Right-Pointing-Pointer Vanadate coating is composed of Mg(OH){sub 2}, Li{sub 2}O and V{sub 2}O{sub 5}. - Abstract: Mg-14Li-1Al-0.1Ce alloy is immersed in NH{sub 4}VO{sub 3} + K{sub 3}(Fe(CN){sub 6}) solutions with different NH{sub 4}VO{sub 3} and/or K{sub 3}(Fe(CN){sub 6}) concentrations, and different immersion time. The surface morphology and composition of the vanadate coating are then characterized by scanning electron microscopy with energy dispersion spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS), and the corrosion behavior of the conversion coating is studied by polarization technique and electrochemical impedance spectroscopy (EIS). The experimental results indicate that the vanadate film with better corrosion resistance forms on Mg-Li-Al-Ce surface after the sample is immersed in 30 g L{sup -1} NH{sub 4}VO{sub 3} + 3.75 g L{sup -1} K{sub 3}(Fe(CN){sub 6}) solution at 80 Degree-Sign C for 10 min. The coating consists of V{sub 2}O{sub 5}, Li{sub 2}O and Mg(OH){sub 2}.

Optical absorption and thermoluminescence in Mg O, Mg O:Ni and Mg O:Li irradiated at room temperature

International Nuclear Information System (INIS)

Delgado, L.

1984-01-01

Optical absorption and thermoluminescence (TL) studies in Mg O, Mg O:Ni and Mg O:Li irradiated at room temperature are presented. In pure Mg O the thermal annihilation of Fe3+ by recombination with thermally released electrons at ∼ 90 and 175 degree centigree and the V center annealing by hole release up to 100 degree centigree cause the observed glow peaks at these temperatures. The TL excitation spectrum shows two maxima at 245 nm (electron center) and 288 nm (Fe3+). In Mg O:Ni X irradiation induces Fe 2 + →- Fe 3 + and Ni 2 + → Ni 3 + oxidations. Two TL emission bands centered at 110 degree centigree (red) and 80 o C (green) are assigned to electron release and their recombination at Fe 3 + and Ni 3 + respectively. In Mg O:Li two TL emission bands, one blue (430 nm) and the other red (730 nm) with excitation maxima at 245 nm (electron center) and 200 nm (hole center) respectively are observed. No V-center formation was detected in both Ni and Li doped samples. (Author) 42 refs

Unexpected formation by pulsed laser deposition of nanostructured Fe/olivine thin films on MgO substrates

International Nuclear Information System (INIS)

Legrand, C.; Dupont, L.; Davoisne, C.; Le Marrec, F.; Perriere, J.; Baudrin, E.

2011-01-01

Olivine-type LiFePO 4 thin films were grown on MgO (1 0 0) substrates by pulsed laser deposition (PLD). The formation of an original nanostructure is evidenced by transmission electron microscopy measurements. Indeed, on focused ion beam prepared cross sections of the thin film, we observe, the amazing formation of metallic iron/olivine nanostructures. The appearance of such a structure is explained owing to a topotactic relation between the two phases as well as a strong Mg diffusion from the substrate to the film surface. Magnesium migration is thus concomitant with the creation of metallic iron domains that grow from the core of the film to the surface leading to large protuberances. To the best of our knowledge, this is the first report on iron extrusion from the olivine-type LiFePO 4 . -- Graphical Abstract: HRTEM image of olivine/Fe nanostructure obtained by PLD. Display Omitted Research highlights: → This manuscript describes the attempt to prepare textured LiFePO 4 by PLD. This is presently a challenge to better understand the physical properties of the material, used as cathode in lithium ion batteries. → We describe for the first time the iron extrusion from this material. Indeed, there were recent reports on the possible non-stoichiometry, i.e. lithium or oxygen. However, on the iron side, only some defect were observed for hydrothermally prepared material but the extrusion is new in this paper. → We prepared interesting nanostructures which could be used for different fundamental studies: electric and magnetic measurements.

Trapped magnetic field in a (NdFeB)–(MgB{sub 2}) pair-type bulk magnet

Energy Technology Data Exchange (ETDEWEB)

Aldica, Gheorghe [National Institute of Materials Physics, Atomistilor 105bis, 077125 Magurele, Ilfov (Romania); Burdusel, Mihail [National Institute of Materials Physics, Atomistilor 105bis, 077125 Magurele, Ilfov (Romania); Faculty of Materials Science and Engineering, ‘‘Politehnica’’ University of Bucharest, Splaiul Independentei 316, 060042 Bucharest (Romania); Badica, Petre, E-mail: badica2003@yahoo.com [National Institute of Materials Physics, Atomistilor 105bis, 077125 Magurele, Ilfov (Romania)

2014-10-15

Highlights: • Dense MgB{sub 2} discs were obtained by ex-situ Spark Plasma Sintering. • A NdFeB–MgB{sub 2} pair-type bulk magnet was tested for different working conditions. • The polarity of the NdFeB permanent magnet influences macro flux jumps of MgB{sub 2}. • Trapped field of the pair was 2.45 T (20 K) and 3.3 T (12 K). - Abstract: Superconducting bulk discs, S, of 20 mm in diameter and 3.5 or 3.3 mm thickness of MgB{sub 2} (pristine or added with cubic BN, respectively) with density above 97% were prepared by Spark Plasma Sintering. Discs were combined in a pair-type sandwich-like arrangement with a permanent NdFeB axially magnetised magnet, PM (∼0.5 T). Measurement of the trapped field, B{sub tr}, with temperature, time, and the reduction rate of the applied magnetic field was performed using a Hall sensor positioned at the centre between the superconductor and the permanent magnet. It is shown that the permanent magnet with certain polarity favors higher trapped field of the superconductor owing to suppression of flux jumps specific for high density MgB{sub 2} samples. The B{sub tr} of the PM–S pair was 2.45 T (20 K) and 3.3 T (12 K)

Tratamiento mecanoquímico de la ferrita MgFe2O4

Directory of Open Access Journals (Sweden)

Torralba, J. M.

2000-06-01

Full Text Available Powder of MgFe2O4, previously prepared by solid state reaction, was mechanochemically treated in a centrifugal ball mill in air atmosphere. Different milling conditions has been employed varying ball/powder mass ratio. After low milling time a strong reduction on crystallite size has been detected while the strain lattice increase slowly. The presence of α-Fe2O3 was also observed at different milling time, depending on milling conditions, by means of X-Ray diffraction experiments. Magnetic transition temperatures were evaluated using a thermogravimetric analyser, equipped with a small permanent magnet. An attempt of dependence of magnetic properties with crystallite size has been established.La ferrita MgFe2O4, en forma de polvo y previamente preparada por reacción en estado sólido, se ha sometido a un proceso de molienda mecánica en atmósfera de aire usando un molino centrífugo. Se emplearon diferentes condiciones de molienda variando la relación de peso bolas/ferrita. La variación del tamaño de dominio cristalino o de cristalita y lamicrodeformaciones de red a escala de celda unidad se evaluaron mediante difracción de rayos-X de polvo. Para bajos tiempos de molienda se observó una acusada disminución del tamaño de dominio cristalino, mientras que las microdeformaciones de la red experimentaron un ligero aumento. Así mismo, a partir de determinados tiempos de molienda, se detectó la presencia de α-Fe2O3. Las temperaturas de transición magnética fueron evaluadas a partir de un analizador termogravimétrico equipado con un pequeño imán permanente y se estableció un correlación entre la temperatura de Curie y el tamaño de dominio cristalino.

Fe concentration dependence of tunneling magnetoresistance in magnetic tunnel junctions using group-IV ferromagnetic semiconductor GeFe

Directory of Open Access Journals (Sweden)

Kosuke Takiguchi

2017-10-01

Full Text Available Group-IV-based ferromagnetic semiconductor Ge1−xFex (GeFe is one of the most promising materials for spin injection/detection in Si and Ge. In this paper, we demonstrate a systematic study of tunneling magnetoresistance (TMR in magnetic tunnel junctions (MTJs composed of Fe/MgO/Ge1−xFex with various Fe concentrations (x = 0.065, 0.105, 0.140, and 0.175. With increasing x, the TMR ratio increases up to 1.5% when x≤ 0.105, and it decreases when x> 0.105. This is the first observation of the TMR ratio over 1% in MTJs containing a group-IV ferromagnetic semiconductor. With increasing x, while the Curie temperature of GeFe increases, the MgO surface becomes rougher, which is thought to be the cause of the upper limit of the TMR ratio. The quality of the MgO layer on GeFe is an important factor for further improvement of TMR in Fe/MgO/GeFe MTJs.

Dependence of magnetic anisotropy on MgO sputtering pressure in Co20Fe60B20/MgO stacks

Science.gov (United States)

Kaidatzis, A.; Serletis, C.; Niarchos, D.

2017-10-01

We investigated the dependence of magnetic anisotropy of Ta/Co20Fe60B20/MgO stacks on the Ar partial pressure during MgO deposition, in the range between 0.5 and 15 mTorr. The stacks are studied before and after annealing at 300°C and it is shown that magnetic anisotropy significantly depends on Ar partial pressure. High pressure results in stacks with very low perpendicular magnetic anisotropy even after annealing, while low pressure results in stacks with perpendicular anisotropy even at the as-deposited state. A monotonic increase of magnetic anisotropy energy is observed as Ar partial pressure is decreased.

Effect of Fe2O3 on the sintering and stabilization of ZrO2-MgO system

International Nuclear Information System (INIS)

Longo, E.; Paskocimas, C.A.; Ambrosecchia, J.R.; Weffort, L.C.; Baldo, J.B.; Leite, L.R.; Varela, J.A.

1990-01-01

Through X-ray diffraction, it was studied the influence of the iron oxide (Fe 2 O 3 ) as a mineralizer in the development of partially stabilized zirconia phases (cubic/tetragonal) within the system ZrO 2 -MgO. In the preparation of the studied compositions it was utilized a Brazilian comercial zirconia powder and different precursors for the MgO and Fe 2 O 3 additives. It was observed that the main effect of iron oxide consisted on the speed up of the solid solution formation process of Mg + 2 in the Zr +4 sub-lattice, as well as being a very effective sintering agent. (author) [pt

Some of Physical Properties of Nanostructured (Mg1-xCoxFe2O4 Ferrites Prepared by Sol-Gel Method

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Muhammad Abdul Ammer Alsherefi

2018-01-01

Full Text Available Sol-gel auto combustion technique was used to prepare nanoparticles of magnesium-cobalt ferrites with the chemical formula Mg1-xCoxFe2O4 for  (x=0, 0.2, 0.4, 0.6, 0.8, 1, where x added as weight  percentages, and sintering  at temperature (1100 oC. The X-ray patterns of prepared powder has confirmed the structure of cubic spinel structure (fcc. The prepared samples were composed of nearly spherical nano particles .An average particle size of  magnesium-cobalt ferrite  were  calculated  using  Debye Scherer’s relation is equal 53.12 nm. The surface structure of the samples was investigated by Scanning Electron Microscope(SEM. The electromagnetic properties for prepared samples were investigated using Vector Network Analyzer (VNA in X-band microwave region.

Average [O II] nebular emission associated with Mg II absorbers: dependence on Fe II absorption

Science.gov (United States)

Joshi, Ravi; Srianand, Raghunathan; Petitjean, Patrick; Noterdaeme, Pasquier

2018-05-01

We investigate the effect of Fe II equivalent width (W2600) and fibre size on the average luminosity of [O II] λλ3727, 3729 nebular emission associated with Mg II absorbers (at 0.55 ≤ z ≤ 1.3) in the composite spectra of quasars obtained with 3 and 2 arcsec fibres in the Sloan Digital Sky Survey. We confirm the presence of strong correlations between [O II] luminosity (L_{[O II]}) and equivalent width (W2796) and redshift of Mg II absorbers. However, we show L_{[O II]} and average luminosity surface density suffer from fibre size effects. More importantly, for a given fibre size, the average L_{[O II]} strongly depends on the equivalent width of Fe II absorption lines and found to be higher for Mg II absorbers with R ≡W2600/W2796 ≥ 0.5. In fact, we show the observed strong correlations of L_{[O II]} with W2796 and z of Mg II absorbers are mainly driven by such systems. Direct [O II] detections also confirm the link between L_{[O II]} and R. Therefore, one has to pay attention to the fibre losses and dependence of redshift evolution of Mg II absorbers on W2600 before using them as a luminosity unbiased probe of global star formation rate density. We show that the [O II] nebular emission detected in the stacked spectrum is not dominated by few direct detections (i.e. detections ≥3σ significant level). On an average, the systems with R ≥ 0.5 and W2796 ≥ 2 Å are more reddened, showing colour excess E(B - V) ˜ 0.02, with respect to the systems with R < 0.5 and most likely trace the high H I column density systems.

The mechanical and electronic properties of Al/TiC interfaces alloyed by Mg, Zn, Cu, Fe and Ti: First-principles study

International Nuclear Information System (INIS)

Sun, Ting; Wu, Xiaozhi; Wang, Rui; Li, Weiguo

2015-01-01

The adhesion and ductility of (100) and (110) Al/TiC interfaces alloyed by Mg, Zn, Cu, Fe, and Ti have been investigated using first-principles methods. Fe and Ti can enhance the adhesion of (100) and (110) interfaces. Mg and Zn have the opposite effect. Interfacial electronic structures have been created to analyze the changes of the work of adhesion. It is found that more charge is accumulated at interfaces alloyed by Fe and Ti compared with pure Al/TiC. There is also an obvious downward shift in the Fermi energy of Fe, Ti at the interface. Furthermore, the unstable stacking fault energies of the interfaces are calculated; the results demonstrate that the preferred slip direction is the 〈110〉 direction for (100) and (110) Al/TiC. Based on the Rice criterion of ductility, the results predict that Mg, Fe, and Ti are promising candidates for improving the ductility of Al/TiC interfaces. (paper)

Crystal structure of superparamagnetic Mg0.2Ca0.8Fe2O4 nanoparticles synthesized by sol–gel method

International Nuclear Information System (INIS)

Escamilla-Pérez, A.M.; Cortés-Hernández, D.A.; Almanza-Robles, J.M.; Mantovani, D.; Chevallier, P.

2015-01-01

Powders of magnetic iron oxide nanoparticles (Mg 0.2 Ca 0.8 Fe 2 O 4 ) were prepared by a sol–gel method using ethylene glycol and nitrates of Fe, Ca and Mg as starting materials. Those powders were heat treated at different temperatures (573, 673, 773 and 873 K). In order to evaluate the effect of the heat treatment temperature on the nanoferrites properties, X-ray diffraction (XRD), vibrating sample magnetometry (VSM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) techniques were used. It was found that the reaction products exhibit nanometric sizes and superparamagnetic behavior. It is also demonstrated that, as the heat treatment temperature increases, the particle size and the saturation magnetization of the nanoferrites are increased. - Highlights: • Mg 0.2 Ca 0.8 Fe 2 O 4 superparamagnetic nanoparticles were successfully synthesized. • Particle average sizes of Ca–Mg ferrites were within the range of 8–25 nm. • The nanoferrite treated at 873 K showed a stoichiometry close to Mg 0.2 Ca 0.8 Fe 2 O 4 . • The heat treatment temperature has a strong effect on the crystal structure. • These nanoparticles are potential materials for magnetic hyperthermia

Processing routes evaluation of severely deformed Mg-Fe alloys for hydrogen storage applications

International Nuclear Information System (INIS)

Antiqueira, F.J.; Leiva, D.R.; Ishikawa, T.T.; Jorge Junior, A.M.; Botta, W.J.

2016-01-01

MgH 2 is considered an interesting material for safe hydrogen storage in the solid state, due to its high gravimetric nominal capacity of 7,6%, and the relative low cost of magnesium. In this study, we attempted to improve the performance of the MgH 2 in the hydrogen storage. Different processing routes for Mg and Mg-Fe by severe plastic deformation were evaluated. The prepared materials were characterized by X-ray diffraction (XRD), scanning (SEM) and transmission electron microscopy (TEM). The hydrogen storage properties were evaluated by differential scanning calorimetry and the Sievert's method. The results indicate superior properties to materials catalyzed with iron, as well as a high dependence of hydrogen absorption / desorption kinetic in accordance with the microstructures obtained through the various processing routes. (author)

Preparation of c-axis perpendicularly oriented ultra-thin L10-FePt films on MgO and VN underlayers

Science.gov (United States)

Futamoto, Masaaki; Shimizu, Tomoki; Ohtake, Mitsuru

2018-05-01

Ultra-thin L10-FePt films of 2 nm average thickness are prepared on (001) oriented MgO and VN underlayers epitaxially grown on base substrate of SrTiO3(001) single crystal. Detailed cross-sectional structures are observed by high-resolution transmission electron microscopy. Continuous L10-FePt(001) thin films with very flat surface are prepared on VN(001) underlayer whereas the films prepared on MgO(001) underlayer consist of isolated L10-FePt(001) crystal islands. Presence of misfit dislocation and lattice bending in L10-FePt material is reducing the effective lattice mismatch with respect to the underlayer to be less than 0.5 %. Formation of very flat and continuous FePt layer on VN underlayer is due to the large surface energy of VN material where de-wetting of FePt material at high temperature annealing process is suppressed under a force balance between the surface and interface energies of FePt and VN materials. An employment of underlayer or substrate material with the lattice constant and the surface energy larger than those of L10-FePt is important for the preparation of very thin FePt epitaxial thin continuous film with the c-axis controlled to be perpendicular to the substrate surface.

Simplified sample treatment for the determination of total concentrations and chemical fractionation forms of Ca, Fe, Mg and Mn in soluble coffees.

Science.gov (United States)

Pohl, Pawel; Stelmach, Ewelina; Szymczycha-Madeja, Anna

2014-11-15

A simpler, and faster than wet digestion, sample treatment was proposed prior to determination of total concentrations for selected macro- (Ca, Mg) and microelements (Fe, Mn) in soluble coffees by flame atomic absorption spectrometry. Samples were dissolved in water and acidified with HNO3. Precision was in the range 1-4% and accuracy was better than 2.5%. The method was used in analysis of 18 soluble coffees available on the Polish market. Chemical fractionation patterns for Ca, Fe, Mg and Mn in soluble coffees, as consumed, using a two-column solid-phase extraction method, determined Ca, Mg and Mn were present predominantly as cations (80-93% of total content). This suggests these elements are likely to be highly bioaccessible. Copyright © 2014 Elsevier Ltd. All rights reserved.

Fractionation and risk assessment of Fe and Mn in surface sediments from coastal sites of Sonora, Mexico (Gulf of California).

Science.gov (United States)

Jara-Marini, Martín E; García-Camarena, Raúl; Gómez-Álvarez, Agustín; García-Rico, Leticia

2015-07-01

The aim of this study was to evaluate Fe and Mn distribution in geochemical fractions of the surface sediment of four oyster culture sites in the Sonora coast, Mexico. A selective fractionation scheme to obtain five fractions was adapted for the microwave system. Surface sediments were analyzed for carbonates, organic matter contents, and Fe and Mn in geochemical fractions. The bulk concentrations of Fe ranged from 10,506 to 21,918 mg/kg (dry weight, dry wt), and the bulk concentrations of Mn ranged from 185.1 to 315.9 mg/kg (dry wt) in sediments, which was low and considered as non-polluted in all of the sites. The fractionation study indicated that the major geochemical phases for the metals were the residual, as well as the Fe and Mn oxide fractions. The concentrations of metals in the geochemical fractions had the following order: residual > Fe and Mn oxides > organic matter > carbonates > interchangeable. Most of the Fe and Mn were linked to the residual fraction. Among non-residual fractions, high percentages of Fe and Mn were linked to Fe and Mn oxides. The enrichment factors (EFs) for the two metals were similar in the four studied coasts, and the levels of Fe and Mn are interpreted as non-enrichment (EF < 1) because the metals concentrations were within the baseline concentrations. According to the environmental risk assessment codes, Fe and Mn posed no risk and low risk, respectively. Although the concentrations of Fe and Mn were linked to the residual fraction, the levels in non-residual fractions may significantly result in the transference of other metals, depending on several physico-chemical and biological factors.

Dynamic changes in radial oxygen loss and iron plaque formation and their effects on Cd and As accumulation in rice (Oryza sativa L.).

Science.gov (United States)

Wang, Xun; Yao, Haixin; Wong, Ming Hung; Ye, Zhihong

2013-12-01

Temporal variations and correlations between radial oxygen loss (ROL), iron (Fe) plaque formation, cadmium (Cd) and arsenic (As) accumulation were investigated in two rice cultivars at four different growth stages based upon soil pot and deoxygenated solution experiments. The results showed that there were significant differences in ROL (1.1-16 μmol O(2) plant(-1) h(-1)), Fe plaque formation (4,097-36,056 mg kg(-1)), Cd and As in root tissues (Cd 77-162 mg kg(-1); As 49-199 mg kg(-1)) and Fe plaque (Cd 0.4-24 mg kg(-1); As 185-1,396 mg kg(-1)) between these growth stages. ROL and Fe plaque increased dramatically from tillering to ear emergence stages and then were much reduced at the grain-filling stage. Furthermore, significantly positive correlations were detected between ROL and concentrations of Fe, Cd and As in Fe plaque. Our study indicates that increased Fe plaque forms on rice roots at the ear emergence stage due to the increased ROL. This stage could therefore be an important period to limit the transfer and distribution of Cd and As in rice plants when growing in soils contaminated with these toxic elements.

Efficacy and safety of intravenous alteplase at 0.6 mg/kg more than 3 h after acute middle cerebral artery occlusion in patients selected using perfusion-diffusion mismatch

International Nuclear Information System (INIS)

Nakashima, Kazuya; Ohnishi, Hideyuki; Taomoto, Katsushi; Kuga, Yoshihiro; Kodama, Yuuji; Kubota, Hisashi; Tominaga, Takashi; Hayashi, Masato; Miyata, Shiro

2011-01-01

Thrombolytic treatment with alteplase at 0.6 mg/kg is approved for use within 3 h of stroke onset in Japan. Thus, only a small percentage of patients can benefit. A meta-analysis and more recent studies suggest a benefit to patients beyond 3 h with alteplase at 0.9 mg/kg or desmoteplase. We assessed the efficacy and safety of intravenous alteplase at 0.6 mg/kg more than 3 h after stroke onset in patients with acute MCA occlusion who were selected using perfusion-diffusion mismatch. Patients with MCA occlusion eligible for intravenous alteplase within 3 h were selected using MRI (diffusion-weighted (DW), fluid-attenuated inversion recovery (FLAIR), T2*, T2)/MR angiography (MRA) and beyond 3 h using evidence of perfusion-diffusion mismatch. Recanalization was evaluated using MRA within 24 h after treatment. Baseline characteristics, recanalization rates, early and late good clinical outcomes (National Institute of Health Stroke Scale (NIHSS) scores of 0 to 1 or 8-points or greater improvement at 24 h and mRS scores of 0 or 1 on the 90th day), symptomatic intracranial hemorrhage (within 72 h) and mortality (at the 90th day) were evaluated for both groups. Also for both groups, the relationships between recanalization and early and late good clinical outcomes were evaluated. 63 patients with MCA occlusion were treated using intravenous alteplase within 3 h (n=53) and beyond 3 h (n=10). No statistically significant differences were found between the two groups for recanalization rates (52.8 vs. 70.0%), early and late good clinical outcomes (early: 41.5 vs. 60.0%, late: 37.7 vs. 50.0%), symptomatic intracranial hemorrhage (0 vs. 0%), or mortality (1.9 vs. 0%). Our data suggest that intravenous alteplase at 0.6 mg/kg beyond 3 h after MCA occlusion for patients selected using perfusion-diffusion mismatch has the same efficacy and safety as treatment within 3 h. However, a larger sample size is needed to evaluate the relationship between recanalization and clinical outcomes

Effect of Low-Frequency AC Magnetic Susceptibility and Magnetic Properties of CoFeB/MgO/CoFeB Magnetic Tunnel Junctions

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Yuan-Tsung Chen

2014-01-01

Full Text Available In this investigation, the low-frequency alternate-current (AC magnetic susceptibility (χac and hysteresis loop of various MgO thickness in CoFeB/MgO/CoFeB magnetic tunneling junction (MTJ determined coercivity (Hc and magnetization (Ms and correlated that with χac maxima. The multilayer films were sputtered onto glass substrates and the thickness of intermediate barrier MgO layer was varied from 6 to 15 Å. An experiment was also performed to examine the variation of the highest χac and maximum phase angle (θmax at the optimal resonance frequency (fres, at which the spin sensitivity is maximal. The results reveal that χac falls as the frequency increases due to the relationship between magnetization and thickness of the barrier layer. The maximum χac is at 10 Hz that is related to the maximal spin sensitivity and that this corresponds to a MgO layer of 11 Å. This result also suggests that the spin sensitivity is related to both highest χac and maximum phase angle. The corresponding maximum of χac is related to high exchange coupling. High coercivity and saturation magnetization contribute to high exchange-coupling χac strength.

Optimization of magnetocaloric properties of arc-melted and spark plasma-sintered LaFe{sub 11.6}Si{sub 1.4}

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Shamba, P.; Morley, N.A.; Reaney, I.M.; Rainforth, W.M. [University of Sheffield, Department of Materials Science and Engineering, Sheffield (United Kingdom); Cespedes, O. [University of Leeds, School of Physics and Astronomy, Leeds (United Kingdom)

2016-08-15

LaFe{sub 11.6}Si{sub 1.4} alloy has been synthesized in polycrystalline form using both arc melting and spark plasma sintering (SPS). The phase formation, hysteresis loss and magnetocaloric properties of the LaFe{sub 11.6}Si{sub 1.4} alloys synthesized using the two different techniques are compared. The annealing time required to obtain the 1:13 phase is significantly reduced from 14 days (using the arc melting technique) to 30 min (using the SPS technique). The magnetic entropy change (ΔS{sub M}) for the arc-melted LaFe{sub 11.6}Si{sub 1.4} compound, obtained for a field change of 5 - 0T (decreasing field), was estimated to be 19.6 J kg{sup -1} K{sup -1}. The effective RCP at 5T of the arc-melted LaFe{sub 11.6}Si{sub 1.4} compound was determined to be 360 J kg{sup -1} which corresponds to about 88 % of that observed in Gd. A significant reduction in the hysteretic losses in the SPS LaFe{sub 11.6}Si{sub 1.4} compound was observed. The ΔS{sub M}, obtained for a field change of 5 - 0T (decreasing field), for the SPS LaFe{sub 11.6}Si{sub 1.4} compound decreases to 7.4 J kg{sup -1} K{sup -1}. The T{sub C} also shifts from 186 (arc-melted) to 230 K (SPS) and shifts the order of phase transition from first to second order, respectively. The MCE of the SPS LaFe{sub 11.6}Si{sub 1.4} compound spreads over a larger temperature range with the RCP value at 5T reaching 288 J kg{sup -1} corresponding to about 70 % of that observed in Gd. At low fields, the effective RCP values of the arc-melted and spark plasma-sintered LaFe{sub 11.6}Si{sub 1.4} compounds are comparable, thereby clearly demonstrating the potential of SPS LaFe{sub 11.6}Si{sub 1.4} compounds in low-field magnetic refrigeration applications. (orig.)

The Partial Molar Volume and Compressibility of the FeO Component in Model Basalts (Mixed CaAl2Si2O8-CaMgSi2O6-CaFeSi2O6 Liquids) at 0 GPa: evidence of Fe2+ in 6-fold coordination

Science.gov (United States)

Guo, X.; Lange, R. A.; Ai, Y.

2010-12-01

FeO is an important component in magmatic liquids and yet its partial molar volume at one bar is not as well known as that for Fe2O3 because of the difficulty of performing double-bob density measurements under reducing conditions. Moreover, there is growing evidence from spectroscopic studies that Fe2+ occurs in 4, 5, and 6-fold coordination in silicate melts, and it is expected that the partial molar volume and compressibility of the FeO component will vary accordingly. We have conducted both density and relaxed sound speed measurements on four liquids in the An-Di-Hd (CaAl2Si2O8-CaMgSi2O6-CaFeSi2O6) system: (1) Di-Hd (50:50), (2) An-Hd (50:50), (3) An-Di-Hd (33:33:33) and (4) Hd (100). Densities were measured between 1573 and 1838 K at one bar with the double-bob Archimedean method using molybdenum bobs and crucibles in a reducing gas (1%CO-99%Ar) environment. The sound speeds were measured under similar conditions with a frequency-sweep acoustic interferometer, and used to calculate isothermal compressibility. All the density data for the three multi-component (model basalt) liquids were combined with density data on SiO2-Al2O3-CaO-MgO-K2O-Na2O liquids (Lange, 1997) in a fit to a linear volume equation; the results lead to a partial molar volume (±1σ) for FeO =11.7 ± 0.3(±1σ) cm3/mol at 1723 K. This value is similar to that for crystalline FeO at 298 K (halite structure; 12.06 cm3/mol), which suggests an average Fe2+ coordination of ~6 in these model basalt compositions. In contrast, the fitted partial molar volume of FeO in pure hedenbergite liquid is 14.6 ± 0.3 at 1723 K, which is consistent with an average Fe2+ coordination of 4.3 derived from EXAFS spectroscopy (Rossano, 2000). Similarly, all the compressibility data for the three multi-component liquids were combined with compressibility data on SiO2-Al2O3-CaO-MgO liquids (Ai and Lange, 2008) in a fit to an ideal mixing model for melt compressibility; the results lead to a partial molar

Twiny pro: 5.1 kg of propane dressed in apple green; Twiny pro: 5.1 kg de propane en habillage vert pomme

Energy Technology Data Exchange (ETDEWEB)

Anon.

1998-05-01

Designed for professional and outdoors uses, Twini Pro - the new Primagaz 5.1 kg propane cylinder - is a complement to the Twiny butane 6 kg cylinder was launched during the first week of March in some 2,500 outlets, before 5,000 and 7,000 points later

The Suitability of Zn–1.3%Fe Alloy as a Biodegradable Implant Material

Directory of Open Access Journals (Sweden)

Alon Kafri

2018-02-01

Full Text Available Efforts to develop metallic zinc for biodegradable implants have significantly advanced following an earlier focus on magnesium (Mg and iron (Fe. Mg and Fe base alloys experience an accelerated corrosion rate and harmful corrosion products, respectively. The corrosion rate of pure Zn, however, may need to be modified from its reported ~20 µm/year penetration rate, depending upon the intended application. The present study aimed at evaluating the possibility of using Fe as a relatively cathodic biocompatible alloying element in zinc that can tune the implant degradation rate via microgalvanic effects. The selected Zn–1.3wt %Fe alloy composition produced by gravity casting was examined in vitro and in vivo. The in vitro examination included immersion tests, potentiodynamic polarization and impedance spectroscopy, all in a simulated physiological environment (phosphate-buffered saline, PBS at 37 °C. For the in vivo study, two cylindrical disks (seven millimeters diameter and two millimeters height were implanted into the back midline of male Wister rats. The rats were examined post implantation in terms of weight gain and hematological characteristics, including red blood cell (RBC, hemoglobin (HGB and white blood cell (WBC levels. Following retrieval, specimens were examined for corrosion rate measurements and histological analysis of subcutaneous tissue in the implant vicinity. In vivo analysis demonstrated that the Zn–1.3%Fe implant avoided harmful systemic effects. The in vivo and in vitro results indicate that the Zn–1.3%Fe alloy corrosion rate is significantly increased compared to pure zinc. The relatively increased degradation of Zn–1.3%Fe was mainly related to microgalvanic effects produced by a secondary Zn11Fe phase.

Structural, optical and magnetic studies of CuFe2O4, MgFe2O4 and ZnFe2O4 nanoparticles prepared by hydrothermal/solvothermal method

Science.gov (United States)

Kurian, Jessyamma; Mathew, M. Jacob

2018-04-01

In this paper we report the structural, optical and magnetic studies of three spinel ferrites namely CuFe2O4, MgFe2O4 and ZnFe2O4 prepared in an autoclave under the same physical conditions but with two different liquid medium and different surfactant. We use water as the medium and trisodium citrate as the surfactant for one method (Hydrothermal method) and ethylene glycol as the medium and poly ethylene glycol as the surfactant for the second method (solvothermal method). The phase identification and structural characterization are done using XRD and morphological studies are carried out by TEM. Cubical and porous spherical morphologies are obtained for hydrothermal and solvothermal process respectively without any impurity phase. The optical studies are carried out using FTIR and UV-Vis reflectance spectra. In order to elucidate the nonlinear optical behaviour of the prepared nanomaterial, open aperture z-scan technique is used. From the fitted z-scan curves nonlinear absorption coefficient and the saturation intensity are determined. The magnetic characterization of the samples is performed at room temperature using vibrating sample magnetometer measurements. The M-H curves obtained are fitted using theoretical equation and the different components of magnetization are determined. Nanoparticles with high saturation magnetization are obtained for MgFe2O4 and ZnFe2O4 prepared under solvothermal reaction. The magnetic hyperfine parameters and the cation distribution of the prepared materials are determined using room temperature Mössbauer spectroscopy. The fitted spectra reveal the difference in the magnetic hyperfine parameters owing to the change in size and morphology.

Order-disorder in olivine minerals by synchrotron X-ray absorption near-edge structure (Xane) spectroscopy at the Mg, Fe and Ca K edges

Energy Technology Data Exchange (ETDEWEB)

Wu, Z.; Marcelli, A.; Cibin, G. [Istituto Nazionale di Fisica Nucleare, Frascati, RM (Italy). Laboratori Nazionali di Frascati; Mottana, A. [Istituto Nazionale di Fisica Nucleare, Frascati, RM (Italy). Laboratori Nazionali di Frascati; Rome Univ. Roma Tre, Rome (Italy). Dipt. di Scienze Geologiche; Paris, E.; Giuli, G [INFM, Camerino Univ., Camerino, MC (Italy). Dipt. di Scienze della Terra

1999-07-01

In this paper, are presented new, high-resolution experimental spectra at the Mg and Fe K edges for the two Fe-Mg end members F o and F a, and for three other olivines. Two are the Ca end members of the family, namely monticellite (Mtc: CaMgSiO4) and kirschsteinite (Krs: CaFeSiO4). The main purpose of this work is to investigate the effects of Mg, Fe, and Ca partition in the Pbnm (or {alpha}) olivine structure on the electronic properties, as well as the relationships that exist between chemical substitutions and features occurring in Xanes spectra. One wants to explore the relationships that intervene between LRO, as determined by XRD, and SRO, as determined by Xanes, on the endmembers and on a well-known intermediate member as well, and deduce from it a model for the behavior of the entire olivine solid-solution system.

Order-disorder in olivine minerals by synchrotron X-ray absorption near-edge structure (Xane) spectroscopy at the Mg, Fe and Ca K edges

International Nuclear Information System (INIS)

Wu, Z.; Marcelli, A.; Cibin, G.; Mottana, A.; Rome Univ. Roma Tre, Rome; Paris, E.; Giuli, G.

1999-01-01

In this paper, are presented new, high-resolution experimental spectra at the Mg and Fe K edges for the two Fe-Mg endmembers F o and F a, and for three other olivines. Two are the Ca endmembers of the family, namely monticellite (Mtc: CaMgSiO4) and kirschsteinite (Krs: CaFeSiO4). The main purpose of this work is to investigate the effects of Mg, Fe, and Ca partition in the Pbnm (or α) olivine structure on the electronic properties, as well as the relationships that exist between chemical substitutions and features occurring in Xanes spectra. One wants to explore the relationships that intervene between LRO, as determined by XRD, and SRO, as determined by Xanes, on the endmembers and on a well-known intermediate member as well, and deduce from it a model for the behavior of the entire olivine solid-solution system

The chemical phenol extraction of intermetallic particles from casting AlSi5Cu1Mg alloy.

Science.gov (United States)

Mrówka-Nowotnik, G; Sieniawski, J; Nowotnik, A

2010-03-01

This paper presents a chemical extraction technique for determination of intermetallic phases formed in the casting AlSi5Cu1Mg aluminium alloy. Commercial aluminium alloys contain a wide range of intermetallic particles that are formed during casting, homogenization and thermomechanical processing. During solidification, particles of intermetallics are dispersed in interdendritic spaces as fine primary phases. Coarse intermetallic compounds that are formed in this aluminium alloy are characterized by unique atomic arrangement (crystallographic structure), morphology, stability, physical and mechanical properties. The volume fraction, chemistry and morphology of the intermetallics significantly affect properties and material behaviour during thermomechanical processing. Therefore, accurate determination of intermetallics is essential to understand and control microstructural evolution in Al alloys. Thus, in this paper it is shown that chemical phenol extraction method can be applied for precise qualitative evaluation. The results of optical light microscopy LOM, scanning electron microscopy SEM and X-ray diffraction XRD analysis reveal that as-cast AlSi5Cu1Mg alloy contains a wide range of intermetallic phases such as Al(4)Fe, gamma- Al(3)FeSi, alpha-Al(8)Fe(2)Si, beta-Al(5)FeSi, Al(12)FeMnSi.

Buffer layer dependence of magnetoresistance effects in Co2Fe0.4Mn0.6Si/MgO/Co50Fe50 tunnel junctions

Science.gov (United States)

Sun, Mingling; Kubota, Takahide; Takahashi, Shigeki; Kawato, Yoshiaki; Sonobe, Yoshiaki; Takanashi, Koki

2018-05-01

Buffer layer dependence of tunnel magnetoresistance (TMR) effects was investigated in Co2Fe0.4Mn0.6Si (CFMS)/MgO/Co50Fe50 magnetic tunnel junctions (MTJs). Pd, Ru and Cr were selected for the buffer layer materials, and MTJs with three different CFMS thicknesses (30, 5, and 0.8 nm) were fabricated. A maximum TMR ratio of 136% was observed in the Ru buffer layer sample with a 30-nm-thick CFMS layer. TMR ratios drastically degraded for the CFMS thickness of 0.8 nm, and the values were 26% for Cr buffer layer and less than 1% for Pd and Ru buffer layers. From the annealing temperature dependence of the TMR ratios, amounts of interdiffusion and effects from the lattice mismatch were discussed.

Dose of rocuronium for rapid tracheal intubation following remifentanil 2 μg kg-1 and propofol 2 mg kg-1.

Science.gov (United States)

Oh, Ah-Young; Cho, Suk-Ju; Seo, Kwang-Suk; Ryu, Jung-Hee; Han, Sung-Hee; Hwang, Jung-Won

2013-09-01

Full relaxation is not mandatory for successful tracheal intubation. We tried to find the dose of rocuronium that gave acceptable intubation conditions in a rapid sequence intubation with remifentanil and propofol. A dose-finding study of rocuronium using a modified Dixon's up-and-down method. A single tertiary care teaching hospital. Patients undergoing elective surgery under general anaesthesia. After premedication with midazolam and glycopyrrolate, anaesthesia was induced using remifentanil 2 μg kg and propofol 2 mg kg, and a predetermined dose of rocuronium was administered. The dose of rocuronium was determined by a modified Dixon's up-and-down method starting from 0.8 mg kg with an interval of 0.1 or 0.05 mg kg. Intubation was performed 60 s after the start of the rocuronium injection. Intubation conditions were graded as excellent, good or poor. Excellent or good were regarded as clinically acceptable. A dose of rocuronium needed for acceptable intubation condition in 50% of patients (ED50) during rapid tracheal intubation after induction of anaesthesia with remifentanil and propofol. Twenty-eight patients were enrolled to obtain six crossovers. The ED50 of rocuronium was 0.20 mg kg (95% confidence interval, CI 0.17 to 0.23 mg kg) by a modified Dixon's up-and-down method. After induction of anaesthesia with remifentanil 2 μg kg and propofol 2 mg kg, the ED50 of rocuronium for acceptable intubation condition was 0.20 mg kg (95% CI, 0.17 to 0.23 mg kg) for rapid sequence intubation. Thus, we recommend that the intubation dose should be 0.8 mg kg. Clinical trial registration KCT0000094.

Crystal structure and Mössbauer spectroscopy of a new iron phosphate Mg{sub 2.88}Fe{sub 4.12}(PO{sub 4}){sub 6}

Energy Technology Data Exchange (ETDEWEB)

Saad, Y. [UR Matériaux Inorganiques, Faculté des Sciences, 5019 Monastir (Tunisia); Hidouri, M., E-mail: mourad_hidouri@yahoo.fr [UR Matériaux Inorganiques, Faculté des Sciences, 5019 Monastir (Tunisia); Álvarez-Serrano, I.; Veiga, M.L. [Departamento de Química Inorgánica I, Facultad de Ciencias Químicas, Universidad Complutense, 28040 Madrid (Spain); Wattiaux, A. [Institut de Chimie de la Matière Condensée de Bordeaux, CNRS, Université de Bordeaux I, 87 Avenue du Dr. A. Schweitzer, 33608 Pessac-Cedex (France); Amara, Mongi B. [UR Matériaux Inorganiques, Faculté des Sciences, 5019 Monastir (Tunisia)

2014-01-25

Highlights: • This study reports the synthesis and characterization of a new iron phosphate. • The cationic distribution is supported by a Mössbauer spectroscopy study. • The magnetic susceptibility results are discussed. -- Abstract: A new mixed valence iron phosphate Mg{sub 2.88}Fe{sub 4.12}(PO{sub 4}){sub 6} has been prepared as single crystals by the flux method and as a powder by solid state reaction and its crystal structure has been determined by X-ray diffraction. This compound crystallises in the triclinic system with space group P1{sup ¯} and a = 6.325(5) Å, b = 7.911(3) Å, c = 9.271(3) Å, α = 104.62(1)°, β = 108.41(1)° and γ = 101.24(1)° and Z = 1. Its structure is similar to that of the mineral howardevansite. It consists of Fe{sub 2}O{sub 10} bioctahedral units and MgO{sub 5} trigonal bipyramids sharing edges to form infinite zigzag chains. Such chains are linked to each other by MO{sub 6} (0.88 Mg{sup 2+} + 0.12 Fe{sup 2+}) octahedra and PO{sub 4} tetrahedra resulting in a 3D covalent framework. Magnetic measurements indicated two successive transitions at 46 K and 22 K. Mössbauer spectroscopy confirmed the mixed valence of iron and gave accurate information about its local environment.

Strain and Ferroelectric-Field Effects Co-mediated Magnetism in (011)-CoFe2O4/Pb(Mg1/3Nb2/3)0.7Ti0.3O3Multiferroic Heterostructures

KAUST Repository

Wang, Ping; Jin, Chao; Zheng, Dongxing; Li, Dong; Gong, Junlu; Li, Peng; Bai, Haili

2016-01-01

Electric-field mediated magnetism was investigated in CoFe2O4 (CFO, deposited by reactive cosputtering under different Oxygen flow rates) films fabricated on (011)-Pb(Mg1/3Nb2/3)(0.7)Ti0.3O3 (PMN-PT) substrates. Ascribed to the volatile strain

[Comparison of 1 mg/body and 3 mg/body of intravenous granisetron for the prevention of chemotherapy-induced nausea and vomiting and adverse events in hematological malignancy patients].

Science.gov (United States)

Motohashi, Shinya; Hori, Katsuhito; Ono, Takaaki; Ohnishi, Kazunori; Kawakami, Junichi

2012-01-01

Granisetron is a selective 5-hydroxy tryptamine3 receptor antagonist and widely used for chemotherapy-induced nausea and vomiting (CINV). Recommended dose of intravenous granisetron in the USA and Europe has been set at 0.01 mg/kg (1 mg/body) in the antiemetic treatment guidelines established by the American Society of Clinical Oncology and National Comprehension Cancer Network. In contrast, the approved dose in Japan is 0.04 mg/kg (3 mg/body). Randomized controlled trials (RCTs) which compared 1 mg/body with 3 mg/body of intravenous granisetron for CINV had been reported in Japan. In these RCTs, however, hematological malignancy patients were excluded. We performed observational retrospective study to compare 1 mg/body with 3 mg/body of intravenous granisetron for the prevention of CINV and adverse events in hematological malignancy patients. Number of the patients and chemotherapy courses were 15 and 30 in the 1 mg/body group, and 15 and 27 in the 3 mg/body group, respectively. No nausea rates in the 1 and 3 mg/body group were 83% and 89% of courses, respectively. No vomiting rates in the 1 and 3 mg/body group were 97% and 100% of courses, respectively. The incidences of constipation in the 1 and 3 mg/body group were 34% and 45% of courses, respectively. Anaphylaxis and headache did not occur in both groups. Our findings suggested that 1 mg/body of intravenous granisetron can prevent from CINV in hematological malignancy patients, as well as 3 mg/body.

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

International Nuclear Information System (INIS)

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

2013-01-01

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

Magnetocaloric effects in Mn1.35Fe0.65P1−xSix compounds

International Nuclear Information System (INIS)

Geng Yao-Xiang; Tegus O; Bi Li-Ge

2012-01-01

The structural and magnetocaloric properties of Mn 1.35 Fe 0.65 P 1−x Si x compounds are investigated. The Si-substituted compounds, Mn 1.35 Fe 0.65 P 1−x Si x with x = 0.52, 0.54, 0.55, 0.56, and 0.57, are prepared by high-energy ball milling and the solid-state reaction. The X-ray diffraction shows that the compounds crystallize into the Fe 2 P-type hexagonal structure with space group P6-bar2m. The magnetic measurements show that the Curie temperature of the compound increases from 253 K for x = 0.52 to 296 K for x = 0.56. The isothermal magnetic-entropy change of the Mn 1.35 Fe 0.65 P 1−x Si x compound decreases with the Si content increasing. The maximal value of the magnetic-entropy change is about 7.0 J/kg·K in the Mn 1.35 Fe 0.65 P 0.48 Si 0.52 compound with a field change of 1.5 T. The compound quenched in water possesses a larger magnetic entropy change and a smaller thermal hysteresis than the non-quenched samples. The thermal hysteresis of the compound is less than 3.5 K. The maximum adiabatic temperature change is about 1.4 K in the Mn 1.35 Fe 0.65 P 0.45 Si 0.55 compound with a field change of 1.48 T. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Synthesis of carbon nanotubes from acetylene on the FeCoMgO catalytic system obtained by ball milling

Energy Technology Data Exchange (ETDEWEB)

Biris, A R; Simon, S; Lupu, D; Misan, I [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania); Biris, A S; Dervishi, E; Li, Z; Watanabe, F [UALR Nanotechnology Center, University of Arkansas, 2801 S University Ave, Little Rock, AR 72204 (United States); Lucaci, M, E-mail: alexandru.biris@itim-cj.r [National Institute for Research and Development in Electrical Engineering ICPE-CA 313 Splaiul Unirii, 030138 Bucharest (Romania)

2009-08-01

Highly crystalline multi wall carbon nanotubes have been synthesized by RF-CVD from acetylene at 850{sup 0}C over a Fe:Co:MgO catalyst. The catalytic system was obtained by mixing for 100 h Fe, Co and MgO powders in a ball milling device under petroleum ether environment, followed by oxidation in air at 500{sup 0}C for 24 h. Most of the nanotubes had external diameters in order of dozens of nm and lengths of microns, resulting in an aspect ration of over 1000. Their external to internal diameter ratio varied between 2.5 and 3.

Large spin Hall magnetoresistance and its correlation to the spin-orbit torque in W/CoFeB/MgO structures

Science.gov (United States)

Cho, Soonha; Baek, Seung-heon Chris; Lee, Kyeong-Dong; Jo, Younghun; Park, Byong-Guk

2015-01-01

The phenomena based on spin-orbit interaction in heavy metal/ferromagnet/oxide structures have been investigated extensively due to their applicability to the manipulation of the magnetization direction via the in-plane current. This implies the existence of an inverse effect, in which the conductivity in such structures should depend on the magnetization orientation. In this work, we report a systematic study of the magnetoresistance (MR) of W/CoFeB/MgO structures and its correlation with the current-induced torque to the magnetization. We observe that the MR is independent of the angle between the magnetization and current direction but is determined by the relative magnetization orientation with respect to the spin direction accumulated by the spin Hall effect, for which the symmetry is identical to that of so-called the spin Hall magnetoresistance. The MR of ~1% in W/CoFeB/MgO samples is considerably larger than those in other structures of Ta/CoFeB/MgO or Pt/Co/AlOx, which indicates a larger spin Hall angle of W. Moreover, the similar W thickness dependence of the MR and the current-induced magnetization switching efficiency demonstrates that MR in a non-magnet/ferromagnet structure can be utilized to understand other closely correlated spin-orbit coupling effects such as the inverse spin Hall effect or the spin-orbit spin transfer torques. PMID:26423608

Speciation of Zn, Fe, Ca and Mg in wine with the Donnan Membrane Technique

NARCIS (Netherlands)

Lao, Mireia; Companys, Encarnació; Weng, Liping; Puy, Jaume; Galceran, Josep

2018-01-01

Free concentrations of Zn2+, Fe3+, Ca2+ and Mg2+ in a red wine (Raimat, Catalonia, Spain) have been determined, with the Donnan Membrane Technique (DMT) for the first time. The required equilibration time benefits from the acceptor solution including major cations. K+ and Na+, mainly unbound to any

Atomic data for dielectronic recombination into Mg-like Fe

International Nuclear Information System (INIS)

Murakami, I.; Kato, T.; Kato, D.; Safronova, U.I.; Cowan, T.E.; Ralchenko, Yu.

2006-03-01

Energy levels, radiative transition probabilities, and autoionization rates for 1s 2 2s 2 2p 6 3l'nl (n=3-12, l≤n-1) and 1s 2 2s 2 2p 6 4l'nl (n=4-7, l≤n-1) states in Mg-like iron (Fe 14+ ) are calculated by the Hartree-Fock-Relativistic method (Cowan code) and the relativistic many-body perturbation theory method (RMBPT code). Autoionizing levels above three thresholds 1s 2 2s 2 2p 6 3s, 1s 2 2s 2 2p 6 3p, and 1s 2 2s 2 2p 6 3d are considered. It is found that configuration mixing [3sns + 3pnp + 3dnd], [3snp + 3pns + 3pnd + 3dnp] play an important role for all atomic characteristics. Branching ratios relative to the first threshold and intensity factors for satellite lines are calculated, and dielectronic recombination (DR) rate coefficients are determined for the excited 444 odd-parity and 419 even-parity states. It is shown that the contribution of the highly-excited states is very important for calculation of DR rates. Contribution from the excited 1s 2 2s 2 2p 6 3l'nl states with n≥12 and 1s 2 2s 2 2p 6 4l'nl states with n≥7 to DR rate coefficients are estimated by extrapolation of all atomic characteristics. The total DR rate coefficient is derived as a function of electron temperature. (author)

Influence of elemental diffusion on low temperature formation of MgH2 in TiMn1.3T0.2-Mg (T = 3d-transition elements)

International Nuclear Information System (INIS)

Yamamoto, K.; Tanioka, S.; Tsushio, Y.; Shimizu, T.; Morishita, T.; Orimo, S.; Fujii, H.

1996-01-01

In order to examine the influence of the elemental diffusion from the host compound into the Mg region on low temperature formation of MgH 2 , we have investigated the hydriding properties and the microstructures of the composite materials TiMn 1.3 T 0.2 -Mg (T = V, Cr, Mn, Fe, Co, Ni and Cu). MgH 2 is formed at 353 K in all composite materials. Of all the substitutions, the amount of MgH 2 is the largest in the case of the Cu substitution, which originates from the existence of the Mg-Mg 2 Cu eutectic formed by Cu diffusion from the host compound TiMn 1.3 Cu 0.2 into the Mg region during the liquid phase sintering. In addition, the hydrogen capacity of TiMn 1.3 Cu 0.2 -Mg (that is TiMn 1.3 Cu 0.1 -(Mg+Mg 2 Cu) after the sintering) easily saturates in comparison with TiMn 1.5 -(Mg+Mg 2 Cu) without Cu diffusion. It is concluded that Cu diffusion promotes the mobility of hydrogen atoms at the complex interface between the host compound and the Mg region. (orig.)

Nutritive quality of romanian hemp varieties (Cannabis sativa L. with special focus on oil and metal contents of seeds

Directory of Open Access Journals (Sweden)

Mihoc Marcela

2012-10-01

Full Text Available Abstract Background The study aims to determine the nutritional value of hemp seed expressed by the oil content and by the concentration of metals (Ca, Mg, K, Fe, Mn, Zn and Cd, for five varieties of monoecious and dioecious hemp seeds approved in Romania, comparative with the concentration of these metals in the soil. Results The content of oil in hempseed registers a slight decrease in the production records of 2011, losses due to drought and low levels of precipitation during the growth period. The greatest loss is found in Diana monoecious variety (26.54-20.82% followed by Zenit varieties (27.37-22.97%, Armanca (29.27-25.32%, Silvana (28.89-25.04% and Denise (26.96-25.30%. Siccative hemp oil has a yellowish green color and an iodine index of 140–156 g I2/100 g oil. Hemp seed are rich in mineral based Ca (144–955 mg/100 g seed, Mg (237–694 mg/100 g seed, K (463–2821 mg/100 g seed, Fe (1133-2400 mg.kg-1, Mn (63–110 mg.kg-1 and Zn (42-94 mg.kg-1. For the soil the following macroelements concentrations were determined: Ca (2100–2520 mg.kg-1, Mg (320–376 mg.kg-1 and K (232–257 mg.kg-1. Mn (156–197 mg.kg-1 and Zn (54–67 mg.kg-1 remain within normal limits for Romania. The soils in the experience area contain large amounts of Fe (19000–20430 mg.kg-1. The presence of K in large quantities determines the accumulation of large quantities of Fe in the soil. Conclusion Hempseed belonging to the five Romanian varieties are rich source of nutrients (Ca, Mg, K and unsaturated oil easily digestible by the body, but the presence of Cd concentrations above the upper limit puts a question mark over the use of seeds in various food products. Hemp extracts easily certain metals from the soil. Significant amounts of Fe (1133–2400 mg.kg-1, Mn (63–110 mg.kg-1, Zn (42–94 mg.kg-1 and Cd (1.3-4.0 mg.kg-1 are found in hemp seeds. Hemp (Cannabis sativa L. is included among plants suitable for phytoremediation of soil contaminated with cadmium

Exigências de minerais para cabras durante a gestação: Na, K, Mg, S, Fe e Zn Minerals requirements of goats during the pregnancy: Na, K, Mg, S, F and Zn

Directory of Open Access Journals (Sweden)

Roberto Germano Costa

2003-04-01

Full Text Available O trabalho foi realizado com o objetivo de estimar a retenção e a exigência líquida dos minerais Na, K, Mg, S, Fe e Zn durante a gestação de cabras com um ou dois fetos. A estimativa de retenção foi baseada na diferença entre o total de cada mineral depositado no feto, útero, membranas, fluídos fetais e glândula mamária dos animais nas diferentes etapas da gestação e o total de cada mineral armazenado nas cabras vazias, utilizando-se o modelo de predição ln=A+Bx+Cx2, em que x=tempo de gestação. Os conteúdos de Na, K, Mg, S, Fe e Zn, durante as gestações de um e dois fetos foram de: 13,2 e 21,4 mg; 13,3 e 21,3 g; 2,1 e 3,7 mg; 5,5 e 9,3 mg; 575,5 e 981,0 mg; 112,6 e 164,7 mg nas gestações, resultando em exigências líquidas diárias de 0,13 e 0,11 g; 0,21 e 0,31 g; 0,06 e 0,11g; 0,17 e 0,21 g; 22,94 e 40,51 mg; 2,63 e 2,78 mg, respectivamente.This work was carried out with the purpose of evaluating the retention and the requirement of Ca e P minerals during the pregnancy of goats with one or two foetus. The estimate of retention was based in the difference between the total of each mineral stored in the foetus, uterus, membranes, fetals fluids and mammary gland of animals in the differents phases of pregnancy and the total of each mineral stored in the empty goats, using the model of prediction ln=A+Bx+Cx2, where x=time of pregnancy. The comparison of the estimative with the real values obtained show that the suggested model explained with coherence and precision the biological behavior of minerals retention during all pregnancy. The contend of Na, K, Mg, S, Fe e Zn was: 13.2 and 21.4 mg; 13.3 and 21.3 g; 2.1 and 3.7 mg; 5.5 and 9.3 mg; 575.5 and 981.0 mg; 112.6 and 164.7 mg in the pregnancy of one and two foetus, respectively, that resulted in a diary liquid requirement of 0.13 and 0.11 g; 0.21 and 0.31 g 0.06 and 0.11g; 0.17 and 0.21 g; 22.94 and 40.51 mg; 2.63 and 2.78 mg, respectively.

In vitro application of Fe/MgO nanoparticles as magnetically mediated hyperthermia agents for cancer treatment

Energy Technology Data Exchange (ETDEWEB)

Chalkidou, A. [Department of Physics, Aristotle University of Thessaloniki, 54 124 Thessaloniki (Greece); Molecular Oncology Laboratory, Theagenio Cancer Hospital, Alexandrou Simeonidi Street 2, 54 007 Thessaloniki (Greece); Simeonidis, K. [Department of Physics, Aristotle University of Thessaloniki, 54 124 Thessaloniki (Greece); Angelakeris, M., E-mail: agelaker@auth.g [Department of Physics, Aristotle University of Thessaloniki, 54 124 Thessaloniki (Greece); Samaras, T. [Department of Physics, Aristotle University of Thessaloniki, 54 124 Thessaloniki (Greece); Martinez-Boubeta, C. [Departament d' Electronica, Universitat de Barcelona, Marti i Franques 1, Barcelona 08028 (Spain); Balcells, Ll. [ICMAB-CSIC, Campus UAB, Bellaterra 08193 (Spain); Papazisis, K. [Molecular Oncology Laboratory, Theagenio Cancer Hospital, Alexandrou Simeonidi Street 2, 54 007 Thessaloniki (Greece); Dendrinou-Samara, C. [Department of Chemistry, Aristotle University of Thessaloniki, 54 124 Thessaloniki (Greece); Kalogirou, O. [Department of Physics, Aristotle University of Thessaloniki, 54 124 Thessaloniki (Greece)

2011-03-15

In this work we study the heating efficiency of Fe/MgO magnetic core/biocompatible shell nanoparticles and their in vitro application in magnetic hyperthermia on cancer cells. Different human breast cancer cell lines were used to assess the suitability of nanoparticles for in vivo application. The experiments revealed a very good cytotoxicity profile and significant uptake efficiency together with relatively high specific absorption rates and fast thermal response, features that are crucial for adequate thermal efficiency and minimum duration of treatment. - Research highlights: > Fe/MgO magnetic core/shell nanoparticles and their in vitro application for magnetic hyperthermia. > Very good cytotoxicity profile and significant uptake efficiency in three human breast cancer cell lines. > SAR values and fast thermal response guarantee adequate thermal efficiency and minimum treatment duration.

Enhanced relative cooling power of Fe-doped La{sub 0.67}Sr{sub 0.22}Ba{sub 0.11}Mn{sub 1-x}Fe{sub x}O{sub 3} perovskites: Structural, magnetic and magnetocaloric properties

Energy Technology Data Exchange (ETDEWEB)

Ben Hassine, R.; Cherif, W. [Sfax University, Faculty of Sciences, B. P. 1171, 3000 (Tunisia); Alonso, J.A., E-mail: ja.alonso@icmm.csic.es [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Cantoblanco, E-28049 Madrid (Spain); Mompean, F. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Cantoblanco, E-28049 Madrid (Spain); Fernández-Díaz, M.T. [Institut Laue-Langevin, B.P. 156, F-38042 Grenoble Cedex 9 (France); Elhalouani, F. [Sfax University, National School of Engineers, B. P. W 3038 (Tunisia)

2015-11-15

We present the structural and magnetic properties of a novel series of La{sub 0.67}Sr{sub 0.22}Ba{sub 0.11}Mn{sub 1-x}Fe{sub x}O{sub 3} (0 ≤ x ≤ 0.3) perovskites prepared by the sol–gel method. These oxides were characterized by x-ray (XRD), neutron powder diffraction (NDP) at room temperature and magnetization measurements versus temperature and various applied magnetic fields. The NPD data, very sensitive to the octahedral tilting, show a crystallographic phase transition from an orthorhombic structure (Pnma) for x = 0 to a rhombohedral structure (R-3c) for Fe-doped samples. Magnetic data show that x = 0 and x = 0.1 perovskites exhibit a paramagnetic–ferromagnetic transition at low temperature, while for 0.2 ≤ x ≤ 0.3 a strong divergence between ZFC and FC curves suggest the presence of antagonistic antiferromagnetic and ferromagnetic interactions. The magnetic entropy change (|ΔSmax|) takes values of 2.46 J kg{sup −1} K{sup −1}, 2.43 J kg{sup −1} K{sup −1} and 0.91 J kg{sup −1} for x = 0, x = 0.1 and 0.2, respectively at 5 T. The relative cooling power (RCP) amounts 169 J Kg{sup −1}, 241 J Kg{sup −1} and 70 J Kg{sup −1} at 5 T for x = 0, 0.1, 0.2 respectively. These values are compared favorably with those of some others reported manganites, making La{sub 0.67}Sr{sub 0.22}Ba{sub 0.11}Mn{sub 0.9}Fe{sub 0.1}O{sub 3} a promising candidate for magnetic refrigeration. - Graphical abstract: The title perovskites present a crystallographic phase transition from an orthorhombic structure (Pnma) for x = 0 to a rhombohedral structure (R-3c) for Fe-doped samples, as shown in a neutron study. Magnetic data show that x = 0 and x = 0.1 perovskites exhibit sharp paramagnetic–ferromagnetic transitions. The relative cooling power (RCP) is as high as 241 J Kg{sup −1} for x = 0.1, being a promising candidate for magnetic refrigeration. - Highlights: • Novel Fe-doped manganite oxides prepared by a sol–gel procedure. • Neutron diffraction shows

Synthesis and magnetic properties of LiFePO4 substitution magnesium

Science.gov (United States)

Choi, Hyunkyung; Kim, Min Ji; Hahn, Eun Joo; Kim, Sam Jin; Kim, Chul Sung

2017-06-01

LiFe0.9Mg0.1PO4 sample was prepared by using a solid-state reaction method, and the temperature-dependent magnetic properties of the sample were studied. The X-ray diffraction (XRD) pattern showed an olivine-type orthorhombic structure with space group Pnma based on Rietveld refinement method. The effect of Mg substitution in antiferromagnetic LiFe0.9Mg0.1PO4 was investigated using a vibrating sample magnetometer (VSM) and Mössbauer spectroscopy. The temperature-dependence of the magnetization curves of LiFe0.9Mg0.1PO4 shows abnormal antiferromagnetic behavior with ordering temperature. Sudden changes in both the magnetic hyperfine field (Hhf) and its slope below 15 K suggest that magnetic phase transition associated to the abrupt occurrence of spin-reorientation. The Néel temperature (TN) and spin-reorientation temperature (TS) of LiFe0.9Mg0.1PO4 are lower than those of pure LiFePO4 (TN = 51 K, TS = 23 K). This is due to the Fe-O-Fe superexchange interaction being larger than that of the Fe-O-Mg link. Also, we have confirmed a change in the electric quadrupole splitting (ΔEQ) by the spin-orbit coupling effect and the shape of Mössbauer spectrum has provided the evidence for TS and a strong crystalline field. We have found that Mg ions in LiFe0.9Mg0.1PO4 induce an asymmetric charge density due to the presence of Mg2+ ions at the FeO6 octahedral sites.

Fe_3O_4/carbon nanocomposite: Investigation of capacitive & magnetic properties for supercapacitor applications

International Nuclear Information System (INIS)

Sinan, Neriman; Unur, Ece

2016-01-01

Fe_3O_4 nanoparticles with ∼10 nm diameters were synthesized by an extremely low-cost, scalable and relatively biocompatible chemical co-precipitation method. Magnetic measurements revealed that Fe_3O_4 nanoparticles have bifunctional superparamagnetic and ferromagnetic character with saturation magnetization (M_s) values of 64 and 71 emu g"−"1 at 298 K and 10 K, respectively. Pseudocapacitive Fe_3O_4 nanoparticles were then integrated into hazelnut shells - an abundant agricultural biomass - by an energy efficient hydrothermal carbonization method. Presence of magnesium oxide (MgO) ceramic template or its precursor in the hydrothermal reactor allowed simultaneous introduction of pores into the composite structure. Hierarchically micro-mesoporous Fe_3O_4/C nanocomposite possesses a high specific surface area of 344 m"2 g"−"1. Electrochemical properties of Fe_3O_4/C nanocomposite were investigated by cyclic voltammetry and galvanostatic charge-discharge measurements in a conventional three-electrode cell. The Fe_3O_4/C nanocomposite is able to operate in a large negative potential window in 1 M Na_2SO_4 aqueous electrolyte (−1.2–0 V vs. Ag/AgCl). Synergistic effect of the Fe_3O_4 and carbon leads to enhanced specific capacitance, rate capability and cyclability making Fe_3O_4/C nanocomposite a very promising negative electrode material for asymmetric supercapacitors. - Highlights: • Fe_3O_4 (magnetite) particles with ∼10 nm dia. were prepared by a facile chemical co-precipitation. • Fe_3O_4 nanospheres are superparamagnetic at 298K with high saturation magnetization of 64 emu g"−"1. • Porous Fe_3O_4/C nanocomposite was also prepared by a green HTC method combined with MgO templating. • Electrochemical properties of Fe_3O_4/C were studied in 1 M Na_2SO_4 (between −1.2 and 0 V vs. Ag/AgCl). • Nanocomposite electrode showed high energy density of 27.2 Wh kg"−"1 at 1 A g"−"1.

Influence of Water Deficit on Iron and Zinc Uptake by Matricaria chamomilla L. Influencia del Deficit Hídrico en la Absorción de Hierro y Zinc por Matricaria chamomilla L.

Directory of Open Access Journals (Sweden)

Alireza Pirzad

2012-06-01

Full Text Available Iron and zinc deficiency are a yield-limiting factor with major implications for field crop production in many agricultural regions of the world; this production is essential source of Fe and Zn in human and animal diets. Two experiments were conducted under greenhouse conditions to evaluate Fe and Zn uptake by German chamomile (Matricaria chamomilla L. grown under several drought conditions. Treatments were arranged in four irrigation regimes (95%, 80%, 65%, and 50% field capacity and six irrigation disruptions (stem formation, flower onset, full bloom, first harvest, second harvest, and control without disruption based on a randomized complete block design with five and four replicates in experiments 1 and 2, respectively. In Experiment 1, the irrigation regimes had no significant effect on Fe and Zn uptake by German chamomile, which reached total means of Fe (39.68 mg kg4 and Zn (29.15 mg kg4. In Experiment 2, the highest amount of Fe (39.0 mg kg4 was obtained from irrigation disruption at first harvest; this is similar to the results of irrigation disruption at flower onset and full bloom. However, irrigation disruption in stem formation (21.3 mg kg4, second harvest (12.95 mg kg4, and the control (7.79 mg kg4 had a decreasing trend of Fe uptake. The maximum value of Zn (40.0 mg kg4 occurred at irrigation disruption at the full bloom stage, which was also similar to irrigation disruption at flower onset and stem formation. However, later irrigation disruptions at the first and second harvest stages caused lower amounts of Zn uptake by chamomile. Therefore, the lowest Zn values were obtained from irrigation disruption at second harvest (5.0 mg kg4 and the control (5.5 mg kg4. Regressions between both Fe or Zn uptake and irrigation showed a binomial function.La deficiencia de hierro y zinc es un factor limitante de la producción con grandes implicaciones para producción de cultivo en terreno en muchas regiones agrícolas del mundo como

Electric field induced lattice strain in pseudocubic Bi(Mg{sub 1/2}Ti{sub 1/2})O{sub 3}-modified BaTiO{sub 3}-BiFeO{sub 3} piezoelectric ceramics

Energy Technology Data Exchange (ETDEWEB)

Fujii, Ichiro, E-mail: ifujii@rins.ryukoku.ac.jp [Department of Materials Chemistry, Ryukoku University, Otsu, Shiga 520-2194 (Japan); Iizuka, Ryo; Ueno, Shintaro; Nakashima, Kouichi; Wada, Satoshi [Interdisciplinary Graduate School of Medical and Engineering, University of Yamanashi, Kofu, Yamanashi 400-8510 (Japan); Nakahira, Yuki; Sunada, Yuya; Magome, Eisuke; Moriyoshi, Chikako; Kuroiwa, Yoshihiro [Department of Physical Science, Hiroshima University, Higashihiroshima, Hiroshima 739-8526 (Japan)

2016-04-25

Contributions to the piezoelectric response in pseudocubic 0.3BaTiO{sub 3}-0.1Bi(Mg{sub 1/2}Ti{sub 1/2})O{sub 3}-0.6BiFeO{sub 3} ceramics were investigated by synchrotron X-ray diffraction under electric fields. All of the lattice strain determined from the 110, 111, and 200 pseudocubic diffraction peaks showed similar lattice strain hysteresis that was comparable to the bulk butterfly-like strain curve. It was suggested that the hysteresis of the lattice strain and the lack of anisotropy were related to the complex domain structure and the phase boundary composition.

CALPHAD simulation of the Mg–(Mn, Zr)–Fe system and experimental comparison with as-cast alloy microstructures as relevant to impurity driven corrosion of Mg-alloys

Energy Technology Data Exchange (ETDEWEB)

Gandel, D.S., E-mail: darren.gandel@monash.edu [CAST Cooperative Research Centre (Australia); Department of Materials Engineering, Monash University, Clayton, VIC 3800 (Australia); Easton, M.A. [CAST Cooperative Research Centre (Australia); Department of Materials Engineering, Monash University, Clayton, VIC 3800 (Australia); Gibson, M.A. [CAST Cooperative Research Centre (Australia); CSIRO Process Science and Engineering, Clayton, VIC 3168 (Australia); Birbilis, N. [CAST Cooperative Research Centre (Australia); Department of Materials Engineering, Monash University, Clayton, VIC 3800 (Australia)

2014-02-14

Four Mg alloys with variations in the ratio of Mn, Zr and Fe additions were cast and their microstructures analysed via electron microscopy. Thermodynamic calculations of the expected phases using PANDAT were evaluated with actual as-cast microstructures. Some of the as-cast alloys did appear to form phases similar to those anticipated from the PANDAT calculations. Furthermore, there was a new Mn–Fe particle interaction observed that was not predicted, but which is posited to be responsible for the increase in corrosion resistance among Mn containing Mg alloys with Fe impurities. The experimental work herein has been shown to be invaluable in the understanding of this practically important system with sparingly soluble Fe and its potential influence on the corrosion of Mg alloys. - Highlights: • Alloy microstructure of the Mg-(Mn,Zr, Fe) system was analysed and reported. • CALPHAD analysis was used in conjunction with traditional SEM analysis techniques in this study. • A proposed Mn–Fe interaction within Mg has been observed for the first time. • Experimental validation of calculated phases is required to understand the effect of Mn and Zr on Mg.

Constraining Thermal Histories by Monte Carlo Simulation of Mg-Fe Isotopic Profiles in Olivine

Science.gov (United States)

Sio, C. K. I.; Dauphas, N.

2016-12-01

In thermochronology, random time-temperature (t-T) paths are generated and used as inputs to model fission track data. This random search method is used to identify a range of acceptable thermal histories that can describe the data. We have extended this modeling approach to magmatic systems. This approach utilizes both the chemical and stable isotope profiles measured in crystals as model constraints. Specifically, the isotopic profiles are used to determine the relative contribution of crystal growth vs. diffusion in generating chemical profiles, and to detect changes in melt composition. With this information, tighter constraints can be placed on the thermal evolution of magmatic bodies. We use an olivine phenocryst from the Kilauea Iki lava lake, HI, to demonstrate proof of concept. We treat this sample as one with little geologic context, then compare our modeling results to the known thermal history experienced by that sample. To complete forward modeling, we use MELTS to estimate the boundary condition, initial and quench temperatures. We also assume a simple relationship between crystal growth and cooling rate. Another important parameter is the isotopic effect for diffusion (i.e., the relative diffusivity of the light vs. heavy isotope of an element). The isotopic effects for Mg and Fe diffusion in olivine have been estimated based on natural samples; experiments to better constrain these parameters are underway. We find that 40% of the random t-T paths can be used to fit the Mg-Fe chemical profiles. However, only a few can be used to simultaneously fit the Mg-Fe isotopic profiles. These few t-T paths are close to the independently determined t-T history of the sample. This modeling approach can be further extended other igneous and metamorphic systems where data exist for diffusion rates, crystal growth rates, and isotopic effects for diffusion.

Interface properties of Fe/MgO/Cu-phthalocyanine metal-insulator-organic semiconductor structures

International Nuclear Information System (INIS)

Lee, Nyunjong; Bae, Yujeong; Kim, Taehee; Ito, Eisuke; Hara, Masahiko

2014-01-01

Hybrid interface structures consisting of organic copper-phthalocyanine (CuPc) and ferromagnetic metal Fe(001) with and without a MgO(001) cover were investigated by using surface sensitive techniques of X-ray photoemission spectroscopy and ultraviolet photoemission spectroscopy. A systematic study of the energy level alignment at the interfaces was carried out. For the hybrid interfaces considered here, our results indicate that the insertion of an artificially-grown ultra-thin oxide layer MgO(001) can prevent Femi level pinning and induce a rather large interface dipole, thereby resulting in remarkable CuPc Fermi level shifts when the thickness of the CuPc film is less than 3 nm. This study provides a better understanding of spin filtering in MgO-based organic spin devices and a new way to alter the interface electronic structure of metal/organic semiconductor hybrid systems.

Influence of face-centered-cubic texturing of Co2Fe6B2 pinned layer on tunneling magnetoresistance ratio decrease in Co2Fe6B2/MgO-based p-MTJ spin valves stacked with a [Co/Pd](n)-SyAF layer.

Science.gov (United States)

Takemura, Yasutaka; Lee, Du-Yeong; Lee, Seung-Eun; Chae, Kyo-Suk; Shim, Tae-Hun; Lian, Guoda; Kim, Moon; Park, Jea-Gun

2015-05-15

The TMR ratio of Co2Fe6B2/MgO-based p-MTJ spin valves stacked with a [Co/Pd]n-SyAF layer decreased rapidly when the ex situ magnetic annealing temperature (Tex) was increased from 275 to 325 °C, and this decrease was associated with degradation of the Co2Fe6B2 pinned layer rather than the Co2Fe6B2 free layer. At a Tex above 325 °C the amorphous Co2Fe6B2 pinned layer was transformed into a face-centered-cubic (fcc) crystalline layer textured from [Co/Pd]n-SyAF, abruptly reducing the Δ1 coherence tunneling of perpendicular-spin-torque electrons between the (100) MgO tunneling barrier and the fcc Co2Fe6B2 pinned layer.

Adsorption of Nitrite and Nitrate Ions from an Aqueous Solution by Fe-Mg-Type Hydrotalcites at Different Molar Ratios.

Science.gov (United States)

Ogata, Fumihiko; Nagai, Noriaki; Kariya, Yukine; Nagahashi, Eri; Kobayashi, Yuhei; Nakamura, Takehiro; Kawasaki, Naohito

2018-01-01

In this study, we prepared Fe-Mg-type hydrotalcites (Fe-HT3.0 and Fe-HT5.0) with different molar ratios and evaluated their adsorption capability for nitrite and nitrate ions from aqueous solution. Fe-HT is a typical hydrotalcite-like layered double hydroxide. Adsorption isotherms, as well as the effects of contact time and pH were investigated, and it was found that Fe-HT can adsorb larger amounts of nitrite and nitrate ions than Al-HT (normal-type hydrotalcite). Adsorption isotherm data were fitted to both Freundlich (correlation coefficient: 0.970-1.000) and Langmuir (correlation coefficient: 0.974-0.999) equations. Elemental analysis and binding energy of Fe-HT surface before and after adsorption indicated that the adsorption mechanism was related to the interaction between the adsorbent surface and anions. In addition, the ion exchange process is related to the adsorption mechanism. The adsorption amount increased with increasing temperature (7-25°C). The experimental data fit the pseudo-second-order model better than the pseudo-first-order model. The effect of pH on adsorption was not significant, which suggested that Fe-HT could be used over a wide pH range (4-12). These results indicate that Fe-HT is a good adsorbent for the removal of nitrite and nitrate ions from aqueous solution.

Optimization of Fe2+ supplement in anaerobic digestion accounting for the Fe-bioavailability.

Science.gov (United States)

Cai, Yafan; Zhao, Xiaoling; Zhao, Yubin; Wang, Hongliang; Yuan, Xufeng; Zhu, Wanbin; Cui, Zongjun; Wang, Xiaofen

2018-02-01

Fe is widely used as an additive in anaerobic digestion, but its bioavailability and the mechanism by which it enhances digestion are unclear. In this study, sequential extraction was used to measure Fe bioavailability, while biochemical parameters, kinetics model and Q-PCR (fluorescence quantitative PCR) were used to explore its mechanism of stimulation. The results showed that sequential extraction is a suitable method to assess the anaerobic system bioavailability of Fe, which is low and fluctuates to a limited extent (1.7 to -3.1wt%), indicating that it would be easy for Fe levels to be insufficient. Methane yield increased when the added Fe 2+ was 10-500mg/L. Appropriate amounts of Fe 2+ accelerated the decomposition of rice straw and facilitated methanogen metabolism, thereby improving reactor performance. The modified Gompertz model better fitted the results than the first-order kinetic model. Feasibility analysis showed that addition of Fe 2+ at ≤50mg/L was suitable. Copyright © 2017. Published by Elsevier Ltd.

Electric field-induced ferromagnetic resonance in a CoFeB/MgO magnetic tunnel junction under dc bias voltages

Science.gov (United States)

Kanai, Shun; Gajek, Martin; Worledge, D. C.; Matsukura, Fumihiro; Ohno, Hideo

2014-12-01

We measure homodyne-detected ferromagnetic resonance (FMR) induced by the electric-field effect in a CoFeB/MgO/CoFeB magnetic tunnel junction (MTJ) with perpendicular magnetic easy axis under dc bias voltages up to 0.1 V. From the bias dependence of the resonant frequency, we find that the first order perpendicular magnetic anisotropy is modulated by the applied electric field, whereas the second order component is virtually independent of the electric field. The lineshapes of the FMR spectra are bias dependent, which are explained by the combination of electric-field effect and reflection of the bias voltage from the MTJ.

Characterization of MgMnxFe2-xO4 as a possible cathode material for electrochemical reduction of NOx

DEFF Research Database (Denmark)

Bræstrup, Frantz Radzik; Kammer Hansen, Kent

2009-01-01

Spinel-type oxides of MgMn x Fe2−x O4, x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0, were synthesized as a solid state reaction and characterized with dilatometry and resistivity measurements up to 1000 °C. Results showed a general decrease of the linear expansion and an increase in conductivity as a function...

Bio-transformation and stabilization of arsenic (As) in contaminated soil using arsenic oxidizing bacteria and FeCl3 amendment.

Science.gov (United States)

Karn, Santosh Kumar; Pan, Xiangliang; Jenkinson, Ian R

2017-05-01

A combination of biological and chemical methods was applied in the present study to evaluate the removal of arsenic (As) from contaminated soil. The treatment involved As-oxidizing microbes aimed of transforming the more toxic As (III) to less toxic As (V) in the soil. FeCl 3 was added at three different concentrations (1, 2, and 3%) to stabilize the As (V). Leaching of the treated soil was investigated by making a soil column and passing tap water through it to determine solubility. Experimental results indicated that the bacterial activity had a pronounced positive effect on the transformation of As, and decreased the soluble exchangeable fraction from 50 to 0.7 mg/kg as compared to control and from 50 to 44 mg/kg after 7 days of treatment. FeCl 3 also played an indispensable role in the adsorption/stabilization of As in the soil; 1 and 2% FeCl 3 strongly influenced the adsorption of As (V). The soil leachate contained negligible amount of As and trace metals, which indicates that combining an efficient microbe with a chemical treatment is very effective route for the removal and stabilization of As from contaminated soil in the environment.