WorldWideScience

Sample records for mg na fe

  1. 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.

  2. 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.

  3. Complex transition metal hydrides incorporating ionic hydrogen: Synthesis and characterization of Na{sub 2}Mg{sub 2}FeH{sub 8} and Na{sub 2}Mg{sub 2}RuH{sub 8}

    Energy Technology Data Exchange (ETDEWEB)

    Humphries, Terry D., E-mail: terry_humphries81@hotmail.com [WPI-Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Takagi, Shigeyuki; Li, Guanqiao; Matsuo, Motoaki; Sato, Toyoto [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Sørby, Magnus H.; Deledda, Stefano; Hauback, Bjørn C. [Physics Department, Institute for Energy Technology, Kjeller NO-2027 (Norway); Orimo, Shin-ichi [WPI-Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

    2015-10-05

    Highlights: • Structures of Na{sub 2}Mg{sub 2}FeH{sub 8} and Na{sub 2}Mg{sub 2}RuH{sub 8} have been determined by XRD and PND. • Compounds incorporate independently coordinated ionic and covalent hydrogen. • [TH{sub 6}]{sup 4−} anion is surrounded by a cubic array of four Mg{sup 2+} and four Na{sup +} cations. • H{sup −} anions are octahedrally coordinated by four Na{sup +} and two Mg{sup 2+} cations. • Vibrational modes of the H{sup −} anions and complex hydride anion are observed. - Abstract: A new class of quaternary complex transition metal hydrides (Na{sub 2}Mg{sub 2}TH{sub 8} (T = Fe, Ru)) have been synthesized and their structures determined by combined synchrotron radiation X-ray and powder neutron diffraction. The compounds can be considered as a link between ionic and complex hydrides in terms of incorporating independently coordinated ionic and covalent hydrogen. These novel isostructural complex transition metal hydrides crystallize in the orthorhombic space group Pbam, where the octahedral complex hydride anion is surrounded by a cubic array of four Mg{sup 2+} and four Na{sup +} cations, forming distinct two-dimensional layers. An intriguing feature of these materials is the distorted octahedral coordination of the isolated H{sup −} anions by four Na{sup +} and two Mg{sup 2+} cations, which form layers between the transition metal containing layers. The vibrational modes of the H{sup −} anions and complex hydride anion are independently observed for the first time in a quaternary complex transition metal hydride system by Raman and IR spectroscopy.

  4. Metallic elements (Ca, Hg, Fe, K, Mg, Mn, Na, Zn) in the fruiting bodies of Boletus badius.

    Science.gov (United States)

    Kojta, Anna K; Falandysz, Jerzy

    2016-06-01

    The aim of this study was to investigate and compare the levels of eight metallic elements in the fruiting bodies of Bay Bolete (Boletus badius; current name Imleria badia) collected from ten sites in Poland to understand better the value of this popular mushroom as an organic food. Bay Bolete fruiting bodies were collected from the forest area near the towns and villages of Kętrzyn, Poniatowa, Bydgoszcz, Pelplin, Włocławek, Żuromin, Chełmno, Ełk and Wilków communities, as well as in the Augustów Primeval Forest. Elements such as Ca, Fe, K, Mg, Mn, Na and Zn were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-OES), and mercury by cold vapor atomic absorption spectrometry (CV-AAS). This made it possible to assess the nutritional value of the mushroom, as well as possible toxicological risks associated with its consumption. The results were subjected to statistical analysis (Kruskal-Wallis test, cluster analysis, principal component analysis). Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. 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)

  6. 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.

  7. Quantitative analysis of sodium di-uranate for Al, Ca, Fe, Mg, Mn, Na by flame-atomic absorption spectrometric method

    International Nuclear Information System (INIS)

    Jat, J.R.; Balaji Rao, Y.; Subba Rao, Y.

    2015-01-01

    Nuclear Fuel Complex (NFC) receives Sodium Di-Uranate (SDU) from Uranium Corporation of India Limited (UCIL) for producing sinterable UO 2 pellets for manufacturing fuel sub assemblies. Several impurities present in ore find their way into SDU during its conversion. Stringent specification have been laid down by the reactor designs for achieving the optimum performance of the fuel and several impurity element like Al, Ca, Fe, Mg, Mn, Na among others affects severely performance of UO 2 fuel. Most of the impurity including the above mentioned elements are generally analysed by ICP-OES method. However, determination of Al, Ca, Fe, Mg, Mn and Na by ICP-OES requires lot of dilution as they are present at high levels in SDU. Apart from introducing dilution error, dilution process is very tedious and time consuming work and not a preferred choice in an industrial lab like control lab where large analytical load exists and time bound analysis is a requirement. To avoid these difficulties a simple and reliable Flame Atomic absorption spectrometric technique has been developed for regular analysis. Present method involves dissolution of SDU sample in Conc. HNO 3 and after the complete dissolution the sample solution has been evaporated to near dryness on a hot plate. Subsequently sample solution has been brought into 4N HNO 3 medium

  8. Determination of Ca, Cr, Cu, Fe, K, Mg, Na and Zn in Brazilian medicinal plants by neutron activation and atomic absorption; Determinacao de Ca, Cr, Cu, Fe, K, Mg, Na e Zn em plantas medicinais brasileiras por ativacao neutronica e absorcao atomica

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Ricardo P. de; Sabino, Claudia de Vilhena S.; Franco, Milton B.; Amaral, Angela M.; Guedes, Joao B.; Assis, Adilson de C. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil); Leite, Simone C.A.L.; Silva, Isabel R. [Pontificia Univ. Catolica de Minas Gerais, Belo Horizonte, MG (Brazil)

    2002-07-01

    Medicinal plants are available in the markets in Belo Horizonte, Minas Gerais. The objective of this work is to investigate the Ca, Cr, Cu, Fe, K, Mg, Na e Zn concentrations in two lots of usually known diuretics plants (azeitona do mato, cabelo de milho, cavalinha, cervejinha do campo, chapeu de couro, congonha de bugre, marmelinho do campo and quebra pedra) bought with an interval of time - six months - between the purchases. The elemental concentrations were determined applying k{sub 0} instrumental neutron activation analysis and atomic absorption spectrophotometry analysis. (author)

  9. Study and application of neutron activation analysis and related methods for determination of content of Na, K, Cu, Co, Mn, Ca, Mg, Fe, P and Zn in a lot of speciality fruits of Vietnam (banana, orange, longan, dragon and mango)

    International Nuclear Information System (INIS)

    Nguyen Van Minh; Le Thi Ngoc Trinh; Le Thai Dung; Ta Thi Tuyet Nhung; Nguyen Dang Khoa; Nguyen Tien Dat; Nguyen Thi Hong Tham; Cao Dong Vu

    2007-01-01

    To study the content of trace elements Na, K, Cu, Co, Mn, Ca, Mg, Fe, P and Zn in the speciality fruits is necessary and very important. We collected the studying samples in four Cities such as: Dalat, NhaTrang, HoChiMinh and BinhDuong. The studying samples are: Banana, Orange, Longan, Dragon and Mango. These samples were dried in the Deepfreezer at -40 o C. We analyzed Na, K, Cu, Co, Mn, Ca, Mg, Fe and Zn by neutron activation analysis (INAA, RNAA) and after irradiation measured total β for P. The studying results were shown in the tables. (author)

  10. Study and application of neutron activation analysis and related methods for determination of content of Na, K, Cu, Co, Mn, Ca, Mg, Fe, P and Zn in a lot of speciality fruits of Vietnam (banana, orange, longan, dragon and mango)

    Energy Technology Data Exchange (ETDEWEB)

    Minh, Nguyen Van; Ngoc Trinh, Le Thi; Dung, Le Thai; Tuyet Nhung, Ta Thi; Khoa, Nguyen Dang; Dat, Nguyen Tien; Hong Tham, Nguyen Thi; Vu, Cao Dong [Center for Analytical Techniques, Nuclear Research Institute, Dalat (Viet Nam)

    2007-12-15

    To study the content of trace elements Na, K, Cu, Co, Mn, Ca, Mg, Fe, P and Zn in the speciality fruits is necessary and very important. We collected the studying samples in four Cities such as: Dalat, NhaTrang, HoChiMinh and BinhDuong. The studying samples are: Banana, Orange, Longan, Dragon and Mango. These samples were dried in the Deepfreezer at -40{sup o}C. We analyzed Na, K, Cu, Co, Mn, Ca, Mg, Fe and Zn by neutron activation analysis (INAA, RNAA) and after irradiation measured total {beta} for P. The studying results were shown in the tables. (author)

  11. Sintering and crystallization behavior of CaMgSi2O6-NaFeSi2O6 based glass-ceramics

    International Nuclear Information System (INIS)

    Goel, Ashutosh; Kansal, Ishu; Ferrari, Anna Maria; Pascual, Maria J.; Barbieri, Luisa; Bondioli, Federica; Lancellotti, Isabella; Ribeiro, Manuel J.; Ferreira, Jose M. F.

    2009-01-01

    We report on the synthesis, sintering, and crystallization behaviors of a glass with a composition corresponding to 90 mol % CaMgSi 2 O 6 -10 mol % NaFeSi 2 O 6 . The investigated glass composition crystallized superficially immediately after casting of the melt and needs a high cooling rate (rapid quenching) in order to produce an amorphous glass. Differential thermal analysis and hot-stage microscopy were employed to investigate the glass forming ability, sintering behavior, relative nucleation rate, and crystallization behavior of the glass composition. The crystalline phase assemblage in the glass-ceramics was studied under nonisothermal heating conditions in the temperature range of 850-950 deg. C in both air and N 2 atmosphere. X-ray diffraction studies adjoined with the Rietveld-reference intensity ratio method were employed to quantify the amount of crystalline phases, while electron microscopy was used to shed some light on the microstructure of the resultant glass-ceramics. Well sintered glass-ceramics with diopside as the primary crystalline phase were obtained where the amount of diopside varied with the heating conditions.

  12. Interstitial Fe in MgO

    CERN Document Server

    Mølholt, T E; Gunnlaugsson, H P; Svane, A; Masenda, H; Naidoo, D; Bharuth-Ram, K; Fanciulli, M; Gislason, H P; Johnston, K; Langouche, G; Ólafsson, S; Sielemann, R; Weyer, G

    2014-01-01

    Isolated Fe-57 atoms were studied in MgO single-crystals by emission Mossbauer spectroscopy following implantation of Mn-57 decaying to Fe-57. Four Mossbauer spectral components were found corresponding to different Fe lattice positions and/or charge states. Two components represent Fe atoms substituting Mg as Fe2+ and Fe3+, respectively; a third component is due to Fe in a strongly implantation-induced disturbed region. The fourth component, which is the focus of this paper, can be assigned to Fe at an interstitial site. Comparison of its measured isomer shift with ab initio calculations suggests that the interstitial Fe is located on, or close to, the face of the rock-salt MgO structure. To harmonize such an assignment with the measured near-zero quadrupole interaction a local motion process (cage motion) of the Fe has to be stipulated. The relation of such a local motion as a starting point for long range diffusion is discussed.

  13. 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

  14. Strain mediated magnetoelectric coupling induced in (x) Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-(1−x) MgFe{sub 2}O{sub 4} composites

    Energy Technology Data Exchange (ETDEWEB)

    Manjusha [Smart Materials Research Laboratory, Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Yadav, K.L., E-mail: klyadav35@yahoo.com [Smart Materials Research Laboratory, Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Adhlakha, Nidhi [Elettra-Sincrotrone Trieste S.C.p.A, Area Science Park, I-34012 Trieste (Italy); Shah, Jyoti; Kotnala, R.K. [CSIR-National Physical Laboratory, New Delhi 110012 (India)

    2017-06-01

    Particulate composites of ferroelectric and ferrite phases having general formula (x)Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-(1−x)MgFe{sub 2}O{sub 4} (x=0, 0.5, 0.6, 0.7, 0.8 and 1.0), equivalently denoted as (x)BNT-(1−x)MgFO were synthesized by solid state reaction method. From X-ray diffraction analysis, the structural transformation from tetragonal to rhombohedral corresponding to BNT phase was observed in composites with x=0.5 to x=0.8. Shifting of (012) BNT peak towards left (x=0.5, 0.8) and right side (x=0.6, 0.7) observed due to occupation of Bi{sup 3+} ions at interstitial and substitutional sites into host MgFO lattice respectively. BNT produced strain in MgFO lattice. Scanning electron micrographs show closely packed microstructure with grain size variations from 0.62 to 2.90 µm. The value of magnetoelectric (ME) coupling coefficient increases from 2.42 (x=0.5) to 4.79 (x=0.8) mV/cm. Oe due to strain produced in MgFO and BNT lattices.

  15. New structural family of ternary molybdates NaA3R(MoO4)5, where A is Mg, Mn, Co or Ni and R is Al, In, Cr or Fe

    International Nuclear Information System (INIS)

    Kozhevnikova, N.M.; Kotova, I.Yu

    1998-01-01

    Ternary NaA 3 R(MoO 4 ) 5 molybdates belonging to a new structural family are produced by crystallization from melted solution and by solid-phase synthesis method. NaMg 3 In(MoO 4 ) 5 , NaNi 3 Al(MoO 4 ) 5 and NaCo 3 Al(MoO 4 ) 5 single crystals are grown. Crystallographic and thermal characteristics of NaA 3 R(MoO 4 ) 5 are determined. Structural similarities in MgMoO 4 , NaIn(MoO 4 ) 2 , Na 2 Mg(MoO 4 ) 6 and NaA 3 R(MoO 4 ) 5 series are revealed [ru

  16. Effect of NaFeEDTA-fortified soy sauce on zinc absorption in children.

    Science.gov (United States)

    Li, Min; Wu, Jinghuan; Ren, Tongxiang; Wang, Rui; Li, Weidong; Piao, Jianhua; Wang, Jun; Yang, Xiaoguang

    2015-03-01

    NaFeEDTA has been applied in many foods as an iron fortificant and is used to prevent iron deficiency in Fe-depleted populations. In China, soy sauce is fortified with NaFeEDTA to control iron deficiency. However, it is unclear whether Fe-fortified soy sauce affects zinc absorption. To investigate whether NaFeEDTA-fortified soy sauce affects zinc absorption in children, sixty children were enrolled in this study and randomly assigned to three groups (10 male children and 10 female children in each group). All children received daily 3 mg of (67)Zn and 1.2 mg of dysprosium orally, while the children in the three groups were supplemented with NaFeEDTA-fortified soy sauce (6 mg Fe, NaFeEDTA group), FeSO₄-fortified soy sauce (6 mg Fe, FeSO₄ group), and no iron-fortified soy sauce (control group), respectively. Fecal samples were collected during the experimental period and analyzed for the Zn content, (67)Zn isotope ratio and dysprosium content. The Fe intake from NaFeEDTA-fortified and FeSO₄-fortified groups was significantly higher than that in the control group (P sauce does not affect Zn bioavailability in children.

  17. Behaviour of Fe4O5-Mg2Fe2O5 solid solutions and their relation to coexisting Mg-Fe silicates and oxide phases

    Science.gov (United States)

    Uenver-Thiele, Laura; Woodland, Alan B.; Miyajima, Nobuyoshi; Ballaran, Tiziana Boffa; Frost, Daniel J.

    2018-03-01

    Experiments at high pressures and temperatures were carried out (1) to investigate the crystal-chemical behaviour of Fe4O5-Mg2Fe2O5 solid solutions and (2) to explore the phase relations involving (Mg,Fe)2Fe2O5 (denoted as O5-phase) and Mg-Fe silicates. Multi-anvil experiments were performed at 11-20 GPa and 1100-1600 °C using different starting compositions including two that were Si-bearing. In Si-free experiments the O5-phase coexists with Fe2O3, hp-(Mg,Fe)Fe2O4, (Mg,Fe)3Fe4O9 or an unquenchable phase of different stoichiometry. Si-bearing experiments yielded phase assemblages consisting of the O5-phase together with olivine, wadsleyite or ringwoodite, majoritic garnet or Fe3+-bearing phase B. However, (Mg,Fe)2Fe2O5 does not incorporate Si. Electron microprobe analyses revealed that phase B incorporates significant amounts of Fe2+ and Fe3+ (at least 1.0 cations Fe per formula unit). Fe-L2,3-edge energy-loss near-edge structure spectra confirm the presence of ferric iron [Fe3+/Fetot = 0.41(4)] and indicate substitution according to the following charge-balanced exchange: [4]Si4+ + [6]Mg2+ = 2Fe3+. The ability to accommodate Fe2+ and Fe3+ makes this potential "water-storing" mineral interesting since such substitutions should enlarge its stability field. The thermodynamic properties of Mg2Fe2O5 have been refined, yielding H°1bar,298 = - 1981.5 kJ mol- 1. Solid solution is complete across the Fe4O5-Mg2Fe2O5 binary. Molar volume decreases essentially linearly with increasing Mg content, consistent with ideal mixing behaviour. The partitioning of Mg and Fe2+ with silicates indicates that (Mg,Fe)2Fe2O5 has a strong preference for Fe2+. Modelling of partitioning with olivine is consistent with the O5-phase exhibiting ideal mixing behaviour. Mg-Fe2+ partitioning between (Mg,Fe)2Fe2O5 and ringwoodite or wadsleyite is influenced by the presence of Fe3+ and OH incorporation in the silicate phases.

  18. Raman-spectroscopic (Fe/Fe+Mg, CO2) and Structural studies of Mg-Fe cordierites

    International Nuclear Information System (INIS)

    Haefeker, U.

    2013-01-01

    In the course of this dissertation synthetic hexagonal and orthorhombic Mg-Fe-cordierites have been investigated with Raman-spectroscopy and XRD methods. Cordierite´s Mg- and Fe-end-members as well as their Mg-Fe solid solutions with the chemical formula (Mg, Fe 2+ ) 2 Al 4 Si 5 O 18 *nH 2 O have been synthesized. Raman-data of synthetic hydrous Mg- and Fe-cordierites have been obtained in the wavenumber-region 100-1250 cm-1 and the experimental data were then compared with the results of quantum-mechanical calculations. 86 theoretical bands could be related to specific vibrational modes of the tetrahedral and octahedral sites of the cordierite structure. Maximum and mean deviation between experimentally-derived bands and calculated modes were ±7 cm -1 for Mg-cordierite and ±19 cm -1 for Fe-cordierite. Spectra comparison revealed a trend of peak downshifting as a consequence of Fe-incorporation. The calculations now allow more accurate interpretation of the Raman spectra with respect to structural changes of cordierite, resulting from Al-Si ordering and Mg-Fe exchange. Atomic motions in cordierite have been compared with those of the structurally similar mineral beryl. Investigations of 16 H 2 O-bearing synthetic well-ordered Mg-Fe-cordierites (XFe =0-1) with micro-Raman spectroscopy revealed a linear correlation between the Fe/Mg ratio and the position of certain Raman peaks. The peaks (wave-number Mg-/Fe-cordierite) at 122/111, 262/257, 430/418, 579/571, 974/967, and 1012/1007 cm -1 were selected for a detailed deconvolution analysis . The shifts of these peaks were then plotted vs. XFe and regression of the data lead to the formulation of a set of linear equations. In addition, the effect of different H 2 O contents and the degree of Al-Si ordering on the Fe/Mg determination were also investigated. Testing the calibration against data from six well-characterized natural cordierite samples yielded excellent agreement. Existing calibration diagrams for CO 2

  19. Sintering of (Ni,Mg)(Al,Fe)2O4 Materials and their Corrosion Process in Na3AlF6-AlF3-K3AlF6 Electrolyte

    Science.gov (United States)

    Xu, Yibiao; Li, Yawei; Yang, Jianhong; Sang, Shaobai; Wang, Qinghu

    2017-06-01

    The application of ledge-free sidewalls in the Hall-Héroult cells can potentially reduce the energy requirement of aluminum production by about 30 pct (Nightingale et al. in J Eur Ceram, 33:2761-2765, 2013). However, this approach poses great material challenges since such sidewalls are in direct contact with corrosive electrolyte. In the present paper, (Ni,Mg)(Al,Fe)2O4 materials were prepared using fused magnesia, reactive alumina, nickel oxide, and iron oxide powders as the starting materials. The sintering behaviors of specimens as well as their corrosion resistance to molten electrolyte have been investigated by means of X-ray diffraction and scanning electron microscope. The results show that after firing at temperature ranging from 1673 K (1400 °C) up to 1873 K (1600 °C), all the specimens prepared are composed of single-phase (Ni,Mg)(Al,Fe)2O4 composite spinel, the lattice parameter of which increases with increasing Fe3+ ion concentration. Increasing the iron oxide content enhances densification of the specimens, which is accompanied by the formation of homogeneously distributed smaller pores in the matrix. The corrosion tests show that corrosion layers consist of fluoride and Ni(Al,Fe)2O4 composite spinel grains are produced in specimens with Fe/Al mole ratio no more than 1, whereas dense Ni(Al,Fe)2O4 composite spinel layers are formed on the surface of the specimens with Fe/Al mole ratio more than 1. The dense Ni(Al,Fe)2O4 composite spinel layers formed improve the corrosion resistance of the specimens by inhibiting the infiltration of electrolyte and hindering the chemical reaction between the specimen and electrolyte.

  20. 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.

  1. 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

  2. Experimental investigation and thermodynamic calculation of the Fe-Mg-Mn and Fe-Mg-Ni systems

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Peisheng; Zhao, Jingrui; Xu, Honghui; Liu, Shuhong; Ouyang, Hongwu [Central South Univ., Hunan (China). State Key Lab. of Powder Metallurgy; Du, Yong [Central South Univ., Hunan (China). State Key Lab. of Powder Metallurgy; Harbin Institute of Technology (China). State Key Lab. of Advanced Welding Production Technology; Gang, Tie; Fen, Jicai [Harbin Institute of Technology (China). State Key Lab. of Advanced Welding Production Technology; Zhang, Lijun [Central South Univ., Hunan (China). State Key Lab. of Powder Metallurgy; Bochum Univ. (Germany). ICAMS Inst.; He, Cuiyun [Guangxi Univ. (China). College of Physical Science and Technology

    2011-01-15

    Based on the thermodynamic calculations extrapolated from the corresponding binary sub-systems, four decisive alloys in the Fe-Mg-Mn system and three in the Fe-Mg-Ni system were selected and prepared using a powder metallurgy method to measure the isothermal sections at 500 C in both systems. The prepared samples were annealed at 500 C, and then subjected to X-ray diffraction, optical microscopy, scanning electron microscopy with energy-dispersive X-ray spectrometry as well as electron probe microanalysis. Taking into account the presently obtained experimental data and the experimental data available in the literature, thermodynamic modeling was performed for the above systems. It was found that a direct extrapolation from the corresponding three binary systems can well reproduce all the experimental data in the Fe-Mg-Mn system, while two thermodynamic parameters are needed in the Fe-Mg-Ni system to fit all the experimental data. The liquidus projections and reaction schemes for the Fe-Mg-Mn and Fe-Mg-Ni systems are also presented. (orig.)

  3. 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.

  4. 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.

  5. The role of Mg interface layer in MgO magnetic tunnel junctions with CoFe and CoFeB electrodes

    Directory of Open Access Journals (Sweden)

    Hyunsoo Yang

    2012-03-01

    Full Text Available The tunneling spin polarization (TSP is directly measured from reactively sputter deposited crystalline MgO tunnel barriers with various CoFe(B compositions using superconducting tunneling spectroscopy. We find that the Mg interface layer thickness dependence of TSP values for CoFeB/Mg/MgO junctions is substantially different from those for CoFe/Mg/MgO especially in the pre-annealed samples due to the formation of boron oxide at the CoFeB/MgO interface. Annealing depletes boron at the interface thus requiring a finite Mg interface layer to prevent CoFeOx formation at the CoFeB/MgO interface so that the TSP values can be optimized by controlling Mg thickness.

  6. 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.

  7. The effect of the MgO buffer layer thickness on magnetic anisotropy in MgO/Fe/Cr/MgO buffer/MgO(001)

    Energy Technology Data Exchange (ETDEWEB)

    Kozioł-Rachwał, Anna, E-mail: a.koziolrachwal@aist.go.jp [National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); Nozaki, Takayuki; Zayets, Vadym; Kubota, Hitoshi; Fukushima, Akio; Yuasa, Shinji [National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); Suzuki, Yoshishige [National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)

    2016-08-28

    The relationship between the magnetic properties and MgO buffer layer thickness d was studied in epitaxial MgO/Fe(t)/Cr/MgO(d) layers grown on MgO(001) substrate in which the Fe thickness t ranged from 0.4 nm to 1.1 nm. For 0.4 nm ≤ t ≤ 0.7 nm, a non-monotonic coercivity dependence on the MgO buffer thickness was shown by perpendicular magneto-optic Kerr effect magnetometry. For thicker Fe films, an increase in the buffer layer thickness resulted in a spin reorientation transition from perpendicular to the in-plane magnetization direction. Possible origins of these unusual behaviors were discussed in terms of the suppression of carbon contamination at the Fe surface and changes in the magnetoelastic anisotropy in the system. These results illustrate a method to control magnetic anisotropy in MgO/Fe/Cr/MgO(d) via an appropriate choice of MgO buffer layer thickness d.

  8. 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.

  9. 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

  10. 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.

  11. 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

  12. Beta decay of 31,32Na and 31Mg

    International Nuclear Information System (INIS)

    Klotz, G.; Baumann, P.; Bounajma, M.; Huck, A.; Knipper, A.; Walter, G.; Poves, A.; Retamosa, J.

    1993-01-01

    31,32 Na and 31 Mg beta decays were studied at the CERN on-line mass separator ISOLDE by gamma, gamma-gamma and neutron-gamma measurements. In the 31 Na decay, the assignment of previously reported γ transitions and the observation of a new level at 3760 keV lead to a revised decay scheme. In the 31 Mg → 31 Al decay, a new decay scheme involves ten β branches and three states are reported for the first time. New spectroscopic results have been obtained in the 32 Na β - decay. A previously non-interpreted 1436 keV γ ray is now assigned in the 32 Mg scheme. (author) 33 refs., 16 figs., 12 tabs

  13. 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.

  14. 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).

  15. Adsorption of Na, Mg, and Al atoms on BN nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Beheshtian, Javad [Department of Chemistry, Shahid Rajaee Teacher Training University, P.O. Box: 16875-163, Tehran (Iran, Islamic Republic of); Peyghan, Ali Ahmadi, E-mail: ahmadi.iau@gmail.com [Young Researchers Club, Islamic Azad University, Islamshahr Branch, Tehran (Iran, Islamic Republic of); Bagheri, Zargham [Physics group, Science department, Islamic Azad University, Islamshahr Branch, P.O. Box: 33135-369, Islamshahr, Tehran (Iran, Islamic Republic of)

    2012-12-30

    Adsorption of three metals (Na, Mg, and Al) on the surface of BN nanotubes (BNNT) has been investigated by using density functional theory. Adsorption energies for Na and Al atoms have been calculated to be about - 0.22 to - 0.61 eV, respectively. Upon the metal adsorption, energy gap between highest occupied and lowest unoccupied orbitals of the tube is dramatically decreased, resulting in enhanced electrical conductivity. However, in the case of Mg atom, the low adsorption energy cannot change electronic property of the tube. The semi-conductive BNNT transform to n-type semiconductor after adsorption of Na atom. The metal adsorption modifies work function of the BNNT and consequently the field-emission current densities of metal-BNNT may be significantly enhanced. - Highlights: Black-Right-Pointing-Pointer Adsorption of Na, Mg, and Al atoms on the BN nanotubes (BNNT) was studied. Black-Right-Pointing-Pointer Adsorption energies for Na and Al atoms are about - 0.22 to - 0.61 eV, respectively. Black-Right-Pointing-Pointer Energy gap of the tube dramatically decreases upon the metals adsorption. Black-Right-Pointing-Pointer Semiconductor BNNT transform to n-type ones upon adsorption of Na and Al atoms. Black-Right-Pointing-Pointer The field-emission current densities of metal-BNNT may be significantly enhanced.

  16. Structural and magnetic properties of Ni{sub 0.15}Mg{sub 0.1}Cu{sub 0.3}Zn{sub 0.45}Fe{sub 2}O{sub 4} ferrite prepared by NaOH-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Wei-xiao; Wang, Zhi, E-mail: zhiwang@tju.edu.cn

    2015-09-15

    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{sub 0.15}Mg{sub 0.1}Cu{sub 0.3}Zn{sub 0.45}Fe{sub 2}O{sub 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{sub a}) from 500 to 800 °C. The saturation magnetization (M{sub 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{sub a} = 600 °C has the highest initial permeability (μ{sub i}), lowest coercivity (H{sub c}), largest saturation magnetization (M{sub s}) and satisfactory thermal stability of μ{sub i}. The microstructures of sintered samples were examined using field emission scanning electric microscope (FESEM). The T{sub a} has significant influence on the bulk density, initial permeability, saturation magnetization and coercivity of Ni{sub 0.15}Mg{sub 0.1}Cu{sub 0.3}Zn{sub 0.45}Fe{sub 2}O{sub 4} ferrite.

  17. Na7 [Fe2S6 ] , Na2 [FeS2 ] and Na2 [FeSe2 ] : New 'reduced' sodium chalcogenido ferrates

    Science.gov (United States)

    Stüble, Pirmin; Peschke, Simon; Johrendt, Dirk; Röhr, Caroline

    2018-02-01

    Three new 'reduced' FeII containing sodium chalcogenido ferrates were obtained applying a reductive synthetic route. The mixed-valent sulfido ferrate Na7 [Fe2S6 ] , which forms bar-shaped crystals with metallic greenish luster, was synthesized in pure phase from natural pyrite and elemental sodium at a maximum temperature of 800 °C. Its centrosymmetric triclinic structure (SG P 1 bar , a = 764.15(2), b = 1153.70(2), c = 1272.58(3) pm, α = 62.3325 (7) , β = 72.8345 (8) , γ = 84.6394 (8) ° , Z = 3, R1 = 0.0185) exhibits two crystallographically different [Fe2S6 ] 7 - dimers of edge-sharing [FeS4 ] tetrahedra, with somewhat larger Fe-S distances than in the fully oxidized FeIII dimers of e.g. Na6 [Fe2III S6 ] . In contrast to the localized AFM ordered pure di-ferrates(III), the Curie-Weiss behavior of the magnetic susceptibility proves the rarely observed valence-delocalized S = 9/2 state of the mixed-valent FeIII /FeII dimer. The nearly spin-only value of the magnetic moment combined with the chemical bonding not generally differing from that in pure ferrates(II) and (III), provides a striking argument, that the reduction of the local Fe spin moments observed in all condensed sulfido ferrate moieties is connected with the AFM spin ordering. The two isotypic ferrates(II) Na2 [FeS2 ] and Na2 [FeSe2 ] with chain-like structural units (SG Ibam, a = 643.54(8)/ 660.81(1), b = 1140.2(2)/1190.30(2) c = 562.90(6)/585.59(1) pm, Z = 4, R1 = 0.0372/0.0466) crystallize in the K2 [ZnO2 ] -type structure. Although representing merely further members of the common series of chalcogenido metallates(II) Na2 [MIIQ2 ] , these two new phases, together with Na6 [FeS4 ] and Li2 [FeS2 ] , are the only examples of pure FeII alkali chalcogenido ferrates. The new compounds allow for a general comparison of di- and chain ferrates(II) and (III) and mixed-valent analogs concerning the electronic and magnetic properties (including Heisenberg super-exchange and double-exchange interactions

  18. DISTRIBUTION OF MAJOR ELEMENTS (NA, K, CA, MG) IN THE ...

    African Journals Online (AJOL)

    Levels of sodium, potassium, calcium and magnesium were determined in plant organs (bud, flowers, fruit, seed, leaves, stems, roots, cobs, styles, shaft, grains and efflorescences) of three Fadama farms located in Ifaki-Ekiti, Ado-Ekiti and Ikere-Ekiti of Ekiti State, Nigeria. The highest levels of Mg, K, Na and Ca were ...

  19. 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

  20. 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.

  1. 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

  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.

  3. 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

  4. 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

  5. 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.

  6. 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)

  7. 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.

  8. 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.

  9. Structure-function relationships of Na+, K+, ATP, or Mg2+ binding and energy transduction in Na,K-ATPase

    DEFF Research Database (Denmark)

    Jorgensen, Peter L.; Pedersen, Per Amstrup

    2000-01-01

    Na,K-ATPase; Mutagenesis; Na+ binding; K+ binding; Tl+ binding; Mg2+ binding; ATP binding; Cation binding site; Energy transduction......Na,K-ATPase; Mutagenesis; Na+ binding; K+ binding; Tl+ binding; Mg2+ binding; ATP binding; Cation binding site; Energy transduction...

  10. 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.

  11. 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)

  12. 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).

  13. 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.

  14. 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.

  15. Resonant proton scattering of $^{22}$Mg and $^{21}$Na

    CERN Multimedia

    Di julio, D D; Jansson, K; Rudolph, D; Fynbo, H O U; Nilsson, T; Perea martinez, A

    In our letter-of-intent, INTC-I-051, we discussed the physics case for scattering and transfer reactions involving light nuclei in the break-out region of the rp-process. The Committee found the physics case compelling and supported the letter-of-intent under the premise that beams of proper quality were developed and that an adequate detector set-up was presented. As these two requirements have been met recently we now propose to study resonant proton scattering of $^{22}$Mg to identify the states at 1.733 MeV and 2.575 MeV in $^{23}$Al that have been reported from the $^{24}$Mg($^{7}$Li,$^{8}$He)$\\,^{23}\\!$Al reaction but that remained unobserved in the only resonant proton scattering experiment performed with $^{22}$Mg so far. In particular we should be able to investigate the character of the proton emission of the 2.575 MeV state which may also have a significant inelastic branch. We also propose to perform resonant proton scattering on $^{21}$Na above $\\alpha$-particle threshold with $^{18}$Ne to study ...

  16. 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.

  17. 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

  18. 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

  19. SIFAT PROOKSIDATIF FORTIFIKAN NaFeEDTA, DENGAN KECAP KEDELAI MANIS SEBAGAI MAKANAN PEMBAWA, DALAM SISTEM BIOLOGIS (TIKUS Oxidative Effect of NaFeEDTA Fortificant in Sweet Soy Sauce as Fortification Vehicle, on Biological System (Rats

    Directory of Open Access Journals (Sweden)

    Sri Naruki Naruki

    2012-05-01

    Full Text Available In vivo study about the effect of NaFeEDTA fortificant in sweet soy sauce on TBARS value of plasma and liver, as well as on histopathologic changes of liver, intestine, and stomach of Sprague Dawley rats was conducted. The oxida- tive properties were determined using hemoglobin depletion-repletion method. During 42 days of repletion periode, iron-depleted rats were fed iron-free diet. NaFeEDTA was ingested in varied dosage, i.e. from 0.175 to 1.4 mg Fe/day for each rat. Sweet soy sauce H O (0.2 mL/day was used as fortification vehicle and H O (0.2 mL/day as a control.2 2FeSO .7H O fortificant (0.35 mg Fe/day, with H O as vehicle was used as reference standard. At the end of the reple-4 2 2tion period, TBARS value of either plasma or liver was analized. The histopathologic changes of liver, intestine, and stomach were also evaluated. The data showed that NaFeEDTA fortificant in sweet soy sauce had no effect on TBARS value of plasma, but it resulted in increased TBARS value of liver. The histopathologic data showed that NaFeEDTA intake up to 0.35 mg Fe/day did not result in histopathologic changes of liver, intestine, and stomach, as well. ABSTRAK Penelitian tentang pengaruh dosis fortifikan NaFeEDTA dalam kecap kedelai manis terhadap angka TBARS plasma dan hati, serta perubahan histopatologik organ hati, usus, dan lambung telah dilakukan pada tikus Sprague Dawley. Evaluasi sifat prooksidatif zat besi dari NaFeEDTA dilakukan dengan metoda deplesi-replesi hemoglobin. Selama peri- ode replesi, tikus yang sebelumnya dibuat anemia, diberi diet basal bebas Fe dan minuman H O. NaFeEDTA diberikan sebagai sumber zat besi, dengan dosis bervariasi, yaitu dari 0,175 sampai dengan 1,40 mg Fe/ekor/hari. Kecap kedelai manis atau H O digunakan sebagai pembawa fortifikan. Fortifikan standar FeSO .7H O (0,35 mg Fe/ekor/hari dalam2 4 2H O digunakan sebagai pembanding. Periode replesi dilakukan selama 42 hari. Pada akhir periode replesi dilakukananalisa angka TBARS

  20. 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.

  1. 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.

  2. 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.

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

    Science.gov (United States)

    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.

  4. 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.

  5. 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.

  6. 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

  7. 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)

  8. 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.

  9. EVALUASI POTENSI KECAP MANIS SEBAGAI PEMBAWA FORTIFIKAN NaFeEDTA: TINJAUAN PENGARUH ASUPAN KECAP KEDELAI MANIS HASIL FORTIFIKASI TERHADAP PENINGKATAN BIOAVAILABILITAS ZAT BESI FORTIFIKAN Potency of Sweet Soy Sauce as Vehicle for NaFeEDTA Fortificant: Eff

    Directory of Open Access Journals (Sweden)

    Sri Naruki

    2012-05-01

    Full Text Available In order to investigate potency of sweet soy sauce as vehicle  for �aFeEDTA fortificant, the effect of sweet soy sauce intake on iron bioavailability of NaFeEDTA, was in vivo evaluated. The bioavailability was determined in Spague- Dawley rats using hemoglobin depletion-repletion method. Rats were iron depleted by feeding them iron-free diet. During the repletion period, iron-depleted rats were fed NaFeEDTA (0.35 mg Fe/day for their iron source of diet, withsweet soy sauce as fortification vehicle. Volume of soy sauce intake was varied from 0.0 to 0.7 mL/day. FeSO .7H O4 2(0.35 mg Fe/day, with H O as vehicle  was used as reference standard. The bioavailability of iron was expressed ashemoglobin regeneration efficiency (HRE. The volume of soy sauce intake which resulted in good bioavailabilitywas used for further study. The further study was done to evaluate the iron bioavailability of NaFeEDTA (dosage was varied from 0.175 to 1.4 mg Fe/day with fixed volume of the fortification vehicle intake (0.2 mL/day. Sweet soy sauce and H O were used as fortification vehicle, while FeSO .7H O (0.35 mg Fe/day, with H O as vehicle was used2 4 2 2as reference standard of fortificant.  The data showed that sweet soy sauce has a good potency  as fortification vehicle for NaFeEDTA. Intake of 0.2 mL of sweet soy sauce/day resulted in HRE of NaFeEDTA as high as HRE of standardFeSO .7H O. Furthermore, in compare with H O vehicle, the soy sauce resulted for higher HRE, higher iron absorp-4 2 2tion, and  higher iron retention, as well. It was found that increased intake of NaFeEDTA made HRE of NaFeEDTA,% A/I, and % R/I decreased. ABSTRAK Pengaruh kecap manis sebagai makanan pembawa terhadap peningkatan bioavailabilitas zat besi fortifikan �aFeEDTA, dievaluasi  secara in vivo, untuk mengetahui potensi kecap manis sebagai pembawa fortifikan tersebut. Bioavailabilitas ditentukan pada tikus Sprague-Dawley, menggunakan metoda deplesi-replesi hemoglobin. Selama

  10. 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.

  11. 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.

  12. 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.

  13. 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}.

  14. 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.

  15. Spin response in LiFeAs and NaFeAs iron-pnictides superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Lochner, Felix; Ahn, Felix; Eremin, Ilya [Ruhr-Universitaet Bochum, Bochum (Germany)

    2016-07-01

    We analyze the spin susceptibility in LiFeAs and NaFeAs by using the ten-orbital tight-binding model that we fitted to the electronic band structure measured by recent ARPES experiments. We identify an effective five-band model for a weak k{sub z}-dependence. Besides we present the bare and RPA-susceptibility and its q{sub z} dependencies to study the magnetic instabilities and estimate the strength of intra-orbital and inter-orbital nesting.

  16. Hydrolysis of Rice Straw Pretreated by Na2SO3 Over Fe-resin/NaCl

    Directory of Open Access Journals (Sweden)

    YANG Hui

    2017-05-01

    Full Text Available To increase the conversion of rice straw(RS and the yield of products, we employed three methods, which were ultrasonic wave, steam explosion and Na2SO3 pretreatment to pretreat RS(the treated RS noted as CS-RS, ZQ-RS and Na2SO3-RS, respectively and found that Na2SO3 treatment was the best pretreatment method based on XRD, SEM, elemental analysis and content of cellulose, hemicellulose and lignin. The conversion of Na2SO3-RS and the yield of total reducing sugar(TRS and levulinic acid(LA were 97.3%, 29.6% and 13.5%, respectively by 10% Fe-resin in 3.3% NaCl solution under 200 ℃.

  17. 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.

  18. 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.

  19. Thermodynamic study of NaFe complex oxides. High temperature properties of Na sub 5 FeO sub 4 and Na sub 3 FeO sub 3

    CERN Document Server

    Furukawa, T

    2002-01-01

    In order to contribute the investigation into corrosion mechanism of the structural materials by leakage sodium, thermodynamic study of Na-Fe complex oxides formed by the reactions was carried out. Na sub 5 FeO sub 4 and Na sub 3 FeO sub 3 were used as the sample. Its high temperature properties (i.e. melting, solidification and transformation) were observed by Differential Scanning Calorimetry, DSC. Moreover, the original test named 'melting point confirmation test' was performed for the observation of traces of melting and solidification after the tests. Following contents have been obtained by this study. (1) Na sub 5 FeO sub 4 was stably as the solid without phase transformation and melting until 800degC. However, the compound was showing a tendency to change into Na sub 4 FeO sub 3 with temperature increasing under the low oxygen potential. (2) The stability of Na sub 3 FeO sub 3 is the same as that of Na sub 5 FeO sub 4 until 700degC. Over the temperature, the compound was changed differential compound ...

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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

  16. 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.

  17. 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

  18. 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.

  19. 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

  20. 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.

  1. A Study of Phase Composition and Structure of Alloys of the Al - Mg - Si - Fe System

    Science.gov (United States)

    Mailybaeva, A. D.; Zolotorevskii, V. S.; Smagulov, D. U.; Islamkulov, K. M.

    2017-03-01

    The Thermo-Calc software is used to compute the phase transformations occurring during cooling of alloys. Polythermal and isothermal sections of the phase diagram of the Al - Mg - Si - Fe system are plotted. The phase composition and the structure of aluminum alloys in cast condition and after a heat treatment are studied experimentally.

  2. 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.

  3. 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

  4. Nematic fluctuations in iron arsenides NaFeAs and LiFeAs probed by 75As NMR

    Science.gov (United States)

    Toyoda, Masayuki; Kobayashi, Yoshiaki; Itoh, Masayuki

    2018-03-01

    75As NMR measurements have been made on single crystals to study the nematic state in the iron arsenides NaFeAs, which undergoes a structural transition from a high-temperature (high-T ) tetragonal phase to a low-T orthorhombic phase at Ts=57 K and an antiferromagnetic transition at TN=42 K, and LiFeAs having a superconducting transition at Tc=18 K. We observe the in-plane anisotropy of the electric field gradient η even in the tetragonal phase of NaFeAs and LiFeAs, showing the local breaking of tetragonal C4 symmetry. Then, η is found to obey the Curie-Weiss (CW) law as well as in Ba (Fe1-xCox) 2As2 . The good agreement between η and the nematic susceptibility obtained by electronic Raman spectroscopy indicates that η is governed by the nematic susceptibility. From comparing η in NaFeAs and LiFeAs with η in Ba (Fe1-xCox) 2As2 , we discuss the carrier-doping dependence of the nematic susceptibility. The spin contribution to nematic susceptibility is also discussed from comparing the CW terms in η with the nuclear spin-lattice relaxation rate divided by temperature 1 /T1T . Finally, we discuss the nematic transition in the paramagnetic orthorhombic phase of NaFeAs from the in-plane anisotropy of 1 /T1T .

  5. 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.)

  6. 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.

  7. Collision based spectroscopy of Na- and Mg-like argon

    International Nuclear Information System (INIS)

    Zou, Y.; Wang, M.; Heijkenskoeld, F.; Hutton, R.

    1997-01-01

    In this work, Ne-like Ar 8+ ions in metastable 2p 5 3s 3 P 0.2 levels from an ECR source were passed through a He gas target to populate core excited levels of Na-like Ar 7+ . The resulting spectra were measured and compared with those from Ar 9+ passing the same He target. The population mechanism for core excited 2p 5 3p 2 based on one electron capture by the metastable Ar 8+ levels is discussed. Our results indicate that the two electron-one photon transitions from 2p 5 3s4p is the main populating process. Also, by increasing the length of the gas target, enhancement of the intensity ratio between lines from long lived and short lived levels was observed. (orig.)

  8. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  11. 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

  12. Thermodynamic modeling of hydrogen storage capacity in Mg-Na alloys.

    Science.gov (United States)

    Abdessameud, S; Mezbahul-Islam, M; Medraj, M

    2014-01-01

    Thermodynamic modeling of the H-Mg-Na system is performed for the first time in this work in order to understand the phase relationships in this system. A new thermodynamic description of the stable NaMgH3 hydride is performed and the thermodynamic models for the H-Mg, Mg-Na, and H-Na systems are reassessed using the modified quasichemical model for the liquid phase. The thermodynamic properties of the ternary system are estimated from the models of the binary systems and the ternary compound using CALPHAD technique. The constructed database is successfully used to reproduce the pressure-composition isotherms for MgH2 + 10 wt.% NaH mixtures. Also, the pressure-temperature equilibrium diagram and reaction paths for the same composition are predicted at different temperatures and pressures. Even though it is proved that H-Mg-Na does not meet the DOE hydrogen storage requirements for onboard applications, the best working temperatures and pressures to benefit from its full catalytic role are given. Also, the present database can be used for thermodynamic assessments of higher order systems.

  13. Thermodynamic Modeling of Hydrogen Storage Capacity in Mg-Na Alloys

    Science.gov (United States)

    Abdessameud, S.; Mezbahul-Islam, M.; Medraj, M.

    2014-01-01

    Thermodynamic modeling of the H-Mg-Na system is performed for the first time in this work in order to understand the phase relationships in this system. A new thermodynamic description of the stable NaMgH3 hydride is performed and the thermodynamic models for the H-Mg, Mg-Na, and H-Na systems are reassessed using the modified quasichemical model for the liquid phase. The thermodynamic properties of the ternary system are estimated from the models of the binary systems and the ternary compound using CALPHAD technique. The constructed database is successfully used to reproduce the pressure-composition isotherms for MgH2 + 10 wt.% NaH mixtures. Also, the pressure-temperature equilibrium diagram and reaction paths for the same composition are predicted at different temperatures and pressures. Even though it is proved that H-Mg-Na does not meet the DOE hydrogen storage requirements for onboard applications, the best working temperatures and pressures to benefit from its full catalytic role are given. Also, the present database can be used for thermodynamic assessments of higher order systems. PMID:25383361

  14. 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.

  15. 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

  16. 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.

  17. Corrosion behaviour of Mg-Cu and Mg-Mo composites in 3.5% NaCl

    International Nuclear Information System (INIS)

    Budruk Abhijeet, S.; Balasubramaniam, R.; Gupta, M.

    2008-01-01

    The corrosion behaviour of pure magnesium, Mg-Cu (0.3, 0.6, and 1 vol.%) and Mg-Mo (0.1, 0.3, and 0.6 vol.%) composites has been studied in 3.5% NaCl solution by weight loss and polarisation methods. Corrosion rates determined by weight loss method were considerably higher than that determined by polarisation method. The corrosion rate increased with increasing volume fraction of reinforcement in Mg-Cu and Mg-Mo composites. At the same volume fraction of reinforcement, molybdenum reinforced composite corroded faster than copper reinforced composite. The galvanic current density between Mg-Cu and Mg-Mo couples has been experimentally measured using zero resistance ammeter technique. The experimentally observed galvanic current densities were in close agreement with those obtained using mixed potential theory analysis. SEM observation of corroded samples confirmed microgalvanic activity at the matrix/reinforcement interfaces. The poor corrosion resistance of composites has been attributed to microgalvanic effects between the matrix and reinforcements and inferior quality of surface films

  18. Structural and magnetic properties of Mg-Zn ferrites (Mg1−xZnxFe2O4) prepared by sol-gel method

    International Nuclear Information System (INIS)

    Reyes-Rodríguez, Pamela Yajaira; Cortés-Hernández, Dora Alicia; Escobedo-Bocardo, José Concepción; Almanza-Robles, José Manuel; Sánchez-Fuentes, Héctor Javier; Jasso-Terán, Argentina; De León-Prado, Laura Elena; Méndez-Nonell, Juan; Hurtado-López, Gilberto Francisco

    2017-01-01

    In this study, the Mg 1−x Zn x Fe 2 O 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 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 0.9 Zn 0.1 Fe 2 O 4 and Mg 0.7 Zn 0.3 Fe 2 O 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 1−x Zn x Fe 2 O 4 were synthesized by sol-gel method. • Nanoparticles showing a single spinel crystalline structure were obtained. • Aqueous suspensions of Mg 0.7 Zn 0.3 Fe 2 O 4 and Mg 0.9 Zn 0.1 Fe 2 O 4 show heating ability.

  19. Comparison of electrochemical performances of olivine NaFePO4 in sodium-ion batteries and olivine LiFePO4 in lithium-ion batteries.

    Science.gov (United States)

    Zhu, Yujie; Xu, Yunhua; Liu, Yihang; Luo, Chao; Wang, Chunsheng

    2013-01-21

    Carbon-coated olivine NaFePO(4) (C-NaFePO(4)) spherical particles with a uniform diameter of ∼80 nm are obtained by chemical delithiation and subsequent electrochemical sodiation of carbon-coated olivine LiFePO(4) (C-LiFePO(4)), which is synthesized by a solvothermal method. The C-NaFePO(4) electrodes are identical (particle size, particle size distribution, surface coating, and active material loading, etc.) to C-LiFePO(4) except that Li ions in C-LiFePO(4) are replaced by Na ions, making them ideal for comparison of thermodynamics and kinetics between C-NaFePO(4) cathode in sodium-ion (Na-ion) batteries and C-LiFePO(4) in lithium-ion (Li-ion) batteries. In this paper, the equilibrium potentials, reaction resistances, and diffusion coefficient of Na in C-NaFePO(4) are systematically investigated by using the galvanostatic intermittent titration technique (GITT), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), and compared to those of the well-known LiFePO(4) cathodes in Li-ion batteries. Due to the lower diffusion coefficient of Na-ion and higher contact and charge transfer resistances in NaFePO(4) cathodes, the rate performance of C-NaFePO(4) in Na-ion batteries is much worse than that of C-LiFePO(4) in Li-ion batteries. However, the cycling stability of C-NaFePO(4) is almost comparable to C-LiFePO(4) by retaining 90% of its capacity even after 100 charge-discharge cycles at a charge-discharge rate of 0.1 C.

  20. 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

  1. 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

  2. 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)

  3. MgO-templated carbon as a negative electrode material for Na-ion capacitors

    Science.gov (United States)

    Kado, Yuya; Soneda, Yasushi

    2016-12-01

    In this study, MgO-templated carbon with different pore structures was investigated as a negative electrode material for Na-ion capacitors. With increasing the Brunauer-Emmett-Teller surface area, the irreversible capacity increased, and the coulombic efficiency of the 1st cycle decreased because of the formation of solid electrolyte interface layers. MgO-templated carbon annealed at 1000 °C exhibited the highest capacity and best rate performance, suggesting that an appropriate balance between surface area and crystallinity is imperative for fast Na-ion storage, attributed to the storage mechanism: combination of non-faradaic electric double-layer capacitance and faradaic Na intercalation in the carbon layers. Finally, a Na-ion capacitor cell using MgO-templated carbon and activated carbon as the negative and positive electrodes, respectively, exhibited an energy density at high power density significantly greater than that exhibited by the cell using a commercial hard carbon negative electrode.

  4. Influence of Na, K, Ca and Mg on lead atomization by tungsten coil atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Oliveira Pedro V. de

    2000-01-01

    Full Text Available The atomization of lead in an electrothermal tungsten coil atomizer in the presence and absence of Na+, K+, Ca2+ and Mg2+ was investigated with the objective of understanding the interference processes. The lead atomization was less affected by Ca2+ and Mg2+ than by Na+ and K+. In the absence of concomitants, lead atomization efficiency was improved by the presence of H2 (10% v/v in the purge gas composition, during pyrolysis and atomization steps. The interference caused by Na+ and Ca2+ was negligible when the pyrolysis step was accomplished without H2 in the purge gas composition. The results showed that Na+, K+, Ca2+ and Mg2+ are directly involved in competition reactions for H2 in condensed phase.

  5. 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.

  6. 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)

  7. 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).

  8. 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...

  9. 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.

  10. 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.

  11. 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)

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. The phase diagrams of KCaF3 and NaMgF3 by ab initio simulations

    Science.gov (United States)

    Jakymiw, Clément; Vočadlo, Lidunka; Dobson, David P.; Bailey, Edward; Thomson, Andrew R.; Brodholt, John P.; Wood, Ian G.; Lindsay-Scott, Alex

    2018-04-01

    ABF3 compounds have been found to make valuable low-pressure analogues for high-pressure silicate phases that are present in the Earth's deep interior and that may also occur in the interiors of exoplanets. The phase diagrams of two of these materials, KCaF3 and NaMgF3, have been investigated in detail by static ab initio computer simulations based on density functional theory. Six ABF3 polymorphs were considered, as follows: the orthorhombic perovskite structure (GdFeO3-type; space group Pbnm); the orthorhombic CaIrO3 structure ( Cmcm; commonly referred to as the "post-perovskite" structure); the orthorhombic Sb2S3 and La2S3 structures (both Pmcn); the hexagonal structure previously suggested in computer simulations of NaMgF3 ( P63/ mmc); the monoclinic structure found to be intermediate between the perovskite and CaIrO3 structures in CaRhO3 ( P21/ m). Volumetric and axial equations of state of all phases considered are presented. For KCaF3, as expected, the perovskite phase is shown to be the most thermodynamically stable at atmospheric pressure. With increasing pressure, the relative stability of the KCaF3 phases then follows the sequence: perovskite → La2S3 structure → Sb2S3 structure → P63/ mmc structure; the CaIrO3 structure is never the most stable form. Above about 2.6 GPa, however, none of the KCaF3 polymorphs are stable with respect to dissociation into KF and CaF2. The possibility that high-pressure KCaF3 polymorphs might exist metastably at 300 K, or might be stabilised by chemical substitution so as to occur within the standard operating range of a multi-anvil press, is briefly discussed. For NaMgF3, the transitions to the high-pressure phases occur at pressures outside the normal range of a multi-anvil press. Two different sequences of transitions had previously been suggested from computer simulations. With increasing pressure, we find that the relative stability of the NaMgF3 phases follows the sequence: perovskite → CaIrO3 structure → Sb2

  17. 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.

  18. 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)

  19. 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)

  20. 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.

  1. Uptake of soil P, Al, Fe, Mn, Mg and Ca by Italian rye grass (Lolium multiflorum Lam. induced by synthetic chelating agent

    Directory of Open Access Journals (Sweden)

    Helinä Hartikainen

    1981-05-01

    Full Text Available The effect of a synthetic chelating compound on the dry matter yield and the uptake of soil P, Al, Fe, Mn, Mg and Ca by Italian rye grass was studied in a pot experiment with three mineral soil samples irrigated with water or 0.001 M Na2-EDTA(dinatrium salt of ethylenediaminetetraacetic acid solution. The Na2-EDTA treatment seemed not to affect the quantity of the dry matter yields, but it affected markedly their chemical composition. Increased contents of P, Al and Fe were found in all the harvests. In two soil samples the P supply was improved by 35—45 %. The accumulation of Al, Fe and Mn induced by Na2-EDTA tended to be the more effective the greater the stability constant for the corresponding metal-EDTA chelate was. Thus, the iron uptake increased most intensively, i.e. by 217—458 %, and that of aluminium by 33—120 %. On the basis of the first two harvests the manganese absorption by the rye grass seemed to decrease probably due to the enormous accumulation of iron. The results also suggested that the addition of Na2-EDTA to the soil was not able essentially to affect the magnesium and calcium supply to the plants.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. High-temperature electromass transfer in the perovskite La-Sr-Ga-Fe-Mg-O ceramics

    International Nuclear Information System (INIS)

    Aleksandrovskij, V.V.; Kaleva, G.M.; Mosunov, A.V.; Politova, E.D.; Stefanovich, S.Yu.; Avetistov, A.K.; Venskovskij, N.U.

    2001-01-01

    Physicochemical mechanism of oxygen-ion transfer in perovskite-like solid solutions within La-Sr-Ga-Fe-Mg-O system was studied using kinetic dependences of oxygen deficit at variation of gas medium composition. One discusses relation between the phenomenon of mass loss, linear deformation and conducting features of a ceramic material. Oxygen-ion transfer was determined to proceed by vacancy jumping mechanism. On the basis of data on dielectric relaxation in lanthanum gallate base solid solutions one obtained new evidences of vacancy correlation under high temperature [ru

  8. 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

  9. Thermodynamic study of sodium-iron oxides. Part 2. Ternary phase diagram of the Na-Fe-O system

    International Nuclear Information System (INIS)

    Huang, Jintao; Furukawa, Tomohiro; Aoto, Kazumi

    2003-01-01

    Studies on ternary phase diagrams of the Na-Fe-O system have been carried out from the thermodynamic point of view. Thermodynamic data of main ternary Na-Fe oxides Na 4 FeO 3 (s), Na 3 FeO 3 (s), Na 5 FeO 4 (s) and Na 8 Fe 2 O 7 (s) have been assessed. A user database has been created by reviewing literature data together with recent DSC and vapor pressure measurements by the present authors. New ternary phase diagrams of the Na-Fe-O system have been constructed from room temperature to 1000K. Stable conditions of the ternary oxides at 800K were presented in predominance diagram as functions of oxygen pressure and sodium pressure

  10. 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

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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...

  16. Spectroscopy of Na-18: Bridging the two-proton radioactivity of Mg-19

    Czech Academy of Sciences Publication Activity Database

    Assie, M.; de Oliveira Santos, F.; Achouri, L.; Angelique, J. C.; Borcea, C.; Borcea, R.; Caceres, L.; Chudoba, V.; Pang, D. Y.; Ducoin, D.; Fallot, M.; Kamalou, O.; Kiener, J.; Lam, Y.; Lefevre, A.; Lotay, G.; Mrázek, Jaromír; Perrot, L.; Sánchez, A.; Rotaru, F.

    2012-01-01

    Roč. 712, č. 3 (2012), s. 198-202 ISSN 0370-2693 Grant - others:European Commission(XE) RII3-CT-2004-506065 Institutional support: RVO:61389005 Keywords : two-proton radioactivity * resonant elastic scattering * (19)mg * Na-18 * Ne-17 Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 4.569, year: 2012

  17. Combustion of Na2B4O7 + Mg + C to synthesis B4C powders

    International Nuclear Information System (INIS)

    Jiang Guojian; Xu Jiayue; Zhuang Hanrui; Li Wenlan

    2009-01-01

    Boron carbide powder was fabricated by combustion synthesis (CS) method directly from mixed powders of borax (Na 2 B 4 O 7 ), magnesium (Mg) and carbon. The adiabatic temperature of the combustion reaction of Na 2 B 4 O 7 + 6 Mg + C was calculated. The control of the reactions was achieved by selecting reactant composition, relative density of powder compact and gas pressure in CS reactor. The effects of these different influential factors on the composition and morphologies of combustion products were investigated. The results show that, it is advantageous for more Mg/Na 2 B 4 O 7 than stoichiometric ratio in Na 2 B 4 O 7 + Mg + C system and high atmosphere pressure in the CS reactor to increase the conversion degree of reactants to end product. The final product with the minimal impurities' content could be fabricated at appropriate relative density of powder compact. At last, boron carbide without impurities could be obtained after the acid enrichment and distilled water washing.

  18. Density functional theory study of hydrogenation mechanism in Fe-doped Mg(0 0 0 1) surface

    International Nuclear Information System (INIS)

    Wu Guangxin; Zhang Jieyu; Wu Yongquan; Li Qian; Chou Kuochih; Bao Xinhua

    2009-01-01

    Using density functional theory (DFT) in combination with nudged elastic band (NEB) method, the dissociative chemisorptions and diffusion processes of hydrogen on both pure and Fe-doped Mg(0 0 0 1) surfaces are studied. Firstly, the dissociation pathway of H 2 and the relative barrier were investigated. The calculated dissociation barrier (1.08 eV) of hydrogen molecule on a pure Mg(0 0 0 1) surface is in good agreement with comparable experimental and theoretical studies. For the Fe-doped Mg(0 0 0 1) surface, the activated barrier decreases to 0.101 eV due to the strong interaction between the s orbital of H and the d orbital of Fe. Then, the diffusion processes of atomic hydrogen on pure and Fe-doped Mg(0 0 0 1) are presented. The obtained diffusion barrier to the first subsurface is 0.45 eV and 0.98 eV, respectively. Finally, Chou method was used to investigate the hydrogen sorption kinetic mechanism of pure MgH 2 and Mg mixed with 5 at.% Fe atoms composites. The obtained activation energies are 0.87 ± 0.02 and 0.31 ± 0.01 eV for H 2 dissociation on the pure surface and H atom diffusion in Fe-doped Mg surfaces, respectively. It suggests that the rate-controlling step is dissociation of H 2 on the pure Mg surface while it is diffusion of H atom in the Fe-doped Mg surface. And both of fitting data are matching well with our calculation results.

  19. The local structure of Ca-Na pyroxenes. 2-Xanes studies at the Mg and A1 K edges

    International Nuclear Information System (INIS)

    Mottana, A.; Cibin, G.; Paris, E.; Giuli, G.; Florence Univ., Florence

    1999-01-01

    X-ray absorption spectra at the Mg and A1 K edges have been recorded on synthetic endmember diopside (Di) and jadeite (Jd) and on a series of natural Fe-poor Ca-Na clinopyroxenes compositionally straddling the Jd-Di join. The spectra of C2/c members of the series (C-omphacites) are different from having P2/n symmetry (P-omphacites). Differences can be explained by theoretical spectra calculated via the multiple-scattering formalism on atomic clusters with at least 89 atoms, extending to a. 0.62 nm away from the Mg viz. A1 absorber: Xanes detects in these systems medium- rather than short-range order-disorder relationships. Near-edge features of C-omphacites reflect the single-type of octahedral arrangement of the back scattering nearest-neighbours (six O atoms) around the absorber (Mg resp. A1) at the centre of the cluster (site M1). Others arise again from medium-range order. P-omphacites show more complicated spectra than C-omphacites. Their additional features reflect the increased local disorder around the probed atom (Mg resp. A1) induced by the two alternative M1, M11 configurations of the six O atoms forming the first co-ordination spheres. Mg and A1 are confirmed to be preferentially partitioned in the M1 resp. M11 site of the P-omphacite crystal structure, however never exclusively, but in a ratio close to 85:15 (plus or minus 10%) that implies a certain degree of local disorder. Changes in the relative heights of some prominent features are more evident in the A1 than in the Mg K-edge spectra. They are diagnostic to qualitatively distinguish C-from P-omphacites

  20. The local structure of Ca-Na pyroxenes. 2-Xanes studies at the Mg and A1 K edges

    Energy Technology Data Exchange (ETDEWEB)

    Mottana, A. [Rome Univ. Roma Tre, Rome (Italy). Dipt. di Scienze Geologiche; Murata, T. [Kyoto University of Education, Kyoto (Japan). Dept. of Physics; Marcelli, A. [Istituto Nazionale di Fisica Nucleare, Frascati, RM (Italy). Laboratori Nazionali di Frascati; Wu, Z.Y. [Istituto Nazionale di Fisica Nucleare, Frascati, RM (Italy). Laboratori Nazionali di Frascati]|[Laboratoire Piere Suee, Gif-sur Yvette Cedex, (France); Cibin, G. [Istituto Nazionale di Fisica Nucleare, Frascati, RM (Italy). Laboratori Nazionali di Frascati; Paris, E. [Camerino Univ., Camerino, MC (Italy). Dipt. di Scienze della Terra; Giuli, G. [Camerino Univ., Camerino, MC (Italy). Dipt. di Scienze della Terra]|[Florence Univ., Florence (Italy). Dipt. di Scienze della Terra

    1999-07-01

    X-ray absorption spectra at the Mg and A1 K edges have been recorded on synthetic end member diopside (Di) and jadeite (Jd) and on a series of natural Fe-poor Ca-Na clinopyroxenes compositionally straddling the Jd-Di join. The spectra of C2/c members of the series (C-omphacites) are different from having P2/n symmetry (P-omphacites). Differences can be explained by theoretical spectra calculated via the multiple-scattering formalism on atomic clusters with at least 89 atoms, extending to a. 0.62 nm away from the Mg viz. A1 absorber: Xanes detects in these systems medium- rather than short-range order-disorder relationships. Near-edge features of C-omphacites reflect the single-type of octahedral arrangement of the back scattering nearest-neighbours (six O atoms) around the absorber (Mg resp. A1) at the centre of the cluster (site M1). Others arise again from medium-range order. P-omphacites show more complicated spectra than C-omphacites. Their additional features reflect the increased local disorder around the probed atom (Mg resp. A1) induced by the two alternative M1, M11 configurations of the six O atoms forming the first co-ordination spheres. Mg and A1 are confirmed to be preferentially partitioned in the M1 resp. M11 site of the P-omphacite crystal structure, however never exclusively, but in a ratio close to 85:15 (plus or minus 10%) that implies a certain degree of local disorder. Changes in the relative heights of some prominent features are more evident in the A1 than in the Mg K-edge spectra. They are diagnostic to qualitatively distinguish C-from P-omphacites.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. Crystal structure of (Na0.70(Na0.70,Mn0.30(Fe3+,Fe2+2Fe2+(VO43, a sodium-, iron- and manganese-based vanadate with the alluaudite-type structure

    Directory of Open Access Journals (Sweden)

    Elhassan Benhsina

    2016-02-01

    Full Text Available The title compound, sodium (sodium,manganese triiron(II,III tris[vanadate(V], (Na0.70(Na0.70,Mn0.30(Fe3+,Fe2+2Fe2+(VO43, was prepared by solid-state reactions. It crystallizes in an alluaudite-like structure, characterized by a partial cationic disorder. In the structure, four of the 12 sites in the asymmetric unit are located on special positions, three on a twofold rotation axis (Wyckoff position 4e and one on an inversion centre (4b. Two sites on the twofold rotation axis are entirely filled by Fe2+ and V5+, whereas the third site has a partial occupancy of 70% by Na+. The site on the inversion centre is occupied by Na+ and Mn2+ cations in a 0.7:0.3 ratio. The remaining Fe2+ and Fe3+ atoms are statistically distributed on a general position. The three-dimensional framework of this structure is made up of kinked chains of edge-sharing [FeO6] octahedra stacked parallel to [10-1]. These chains are held together by VO4 tetrahedral groups, forming polyhedral sheets perpendicular to [010]. Within this framework, two types of channels extending along [001] are present. One is occupied by (Na+/Mn2+ while the second is partially occupied by Na+. The mixed site containing (Na+/Mn2+ has an octahedral coordination sphere, while the Na+ cations in the second channel are coordinated by eight O atoms.

  10. Composition and thermochemistry of the equilibrium vapour of the systems NaI-FeI2 and NaI-PbI2

    International Nuclear Information System (INIS)

    Hilpert, K.; Gerads, H.; Koberts, D.; Miller, M.

    1987-01-01

    The vaporization of NaI/FeI 2 and NaI/PbI 2 samples of equimolar composition was investigated was investigated in the temperature ranges between 574 to 683 K and 562 to 669 K, respectively, by using the mass spectrometric Knudsen effusion method. The gaseous species I, I 2 , NaI, (NaI) 2 , FeI 2 , (FeI 2 ) 2 , FeI 3 , NaFeI 3 , and Na 2 FeI 4 (NaI-FeI 2 system) as well as NaI, (NaI) 2 , PbI 2 , (PbI 2 ) 2 , and NaPbI 3 (NaI-PbI 2 system) are present in the equilibrium vapours. The equilibrium partial pressures of these species were determined with the exception of I, I 2 , and FeI 3 . Enthalpies and entropies of dissociation resulted for the reactions NaFeI 3 (g) ↔ NaI(g)+FeI 2 (g) (1), Na 2 FeI 4 (g) ↔ 2NaI(g)+FeI 2 (g) and (2) NaPbI 3 (g) ↔ NaI(g)+PbI 2 (g) (3) as Δ d H 298 0 (Eq. (1)) = 184±5 kJ mol -1 , Δ d S 298 0 (Eq. (1)) = 143±8 J mol -1 K -1 ; Δ d H 298 0 (Eq. (2)) = 333±9 kJ mol -1 , Δ d S 298 0 (Eq. (2)) = 274±14 J mol -1 K -1 ; and Δ d H 298 0 (Eq. (3)) = 168±5 kJ mol -1 , Δ d S 298 0 (Eq. (3)) = 151±9 J mol -1 K -1 . Equilibrium constants for these reactions are additionally given. The pressures of NaFeI 3 (g) and NaPbI 3 (g) as all as their enthalpies of dissociation are discussed with respect to their significance of semi empirical rules. (orig.)

  11. 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.

  12. High pressure experimental studies on Na3Fe(PO4)(CO3) and Na3Mn(PO4)(CO3): Extensive pressure behaviors of carbonophosphates family

    Science.gov (United States)

    Gao, Jing; Huang, Weifeng; Wu, Xiang; Qin, Shan

    2018-04-01

    Carbon-bearing phases in the Earth's interior have profound implications for the long-term Earth carbon cycle. Here we investigate high-pressure behaviors of carbonophosphates bonshtedtite Na3Fe(PO4)(CO3) and sidorenkite Na3Mn(PO4)(CO3) in diamond anvil cells up to ∼12 GPa at room temperature. Modifications in in situ synchrotron X-ray diffraction patterns and Raman spectra confirm the structural stability of carbonophosphates within the pressure region. Fitting the third-order Birch-Murnaghan equation of state to the volume compression curve, the isothermal bulk modulus parameters are obtained to be K0 = 56(1) GPa, K0' = 3.3(1), V0 = 303.3(3) Å3 for Na3Fe(PO4)(CO3) and K0 = 54(1) GPa, K0' = 3.4(1), V0 = 313.4(2) Å3 for Na3Mn(PO4)(CO3). Crystallographic axes exhibit an elastic anisotropy with a more compressible c-axis relative to the ab-plane. An inverse linear correlation between the K0 value and the ionic radius of M2+ (M = Mg, Fe, Mn) is well determined for carbonophosphates. The pressure-dependence responsiveness of [PO4] and [CO3] in carbonophosphates show a negative relationship to the M2+ radius. We also discussed the effect of [PO4] group on the structural variations and high-pressure behaviors of carbonates. Furthermore, the geochemical properties of carbonophosphates hold implications to diamond genesis.

  13. 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.

  14. 26Mg(p,n)26Al and 23Na(α,n)26Al reactions

    International Nuclear Information System (INIS)

    Skelton, R.T.

    1985-01-01

    Cross sections for the 26 Mg(p,n) 26 Al reaction were measured from threshold at 4.988 MeV to 5.820 MeV. Cross sections for the 23 Na(α,n) 26 Al reaction were measured from threshold at 3.483 MeV to 4.597 MeV. In each case, separate measurements were to the ground state and to the first and second excited states of 26 Al. Cross sections for the inverse reactions were calculated and reaction rate factors relating to the destruction of 26 Al in a supernova environment were determined. Astrophysical implications relating to the observation of live and extinct 26 Al are discussed. Excitation functions for several additional exit channels for the 26 Mg + rho and 23 Na + α reactions are reported

  15. Foaming Index of CaO-SiO2-FeO-MgO Slag System

    Science.gov (United States)

    Park, Youngjoo; Min, Dong Joon

    A study on the effect of FeO and MgO content on foaming index in EAF slag system was carried out. The height of the slag foam was measured by electric probe maintaining steady state in gas formation and escape. Foaming index, which is the measurement of gas capturing potential of the slag, is calculated from the foam height and gas flow rate. Viscosity and surface tension, which are the key properties for the foaming index, are calculated by Urbain's model and additive method, respectively. Dimensional analysis also performed to determine the dominancy of properties and resulted that the important factor was a ratio between viscosity and surface tension. The effect of each component on the viscosity, surface tension and foaming index of the slag is evaluated to be in strong relationship.

  16. Crystalline maricite NaFePO4 as a positive electrode material for sodium secondary batteries operating at intermediate temperature

    Science.gov (United States)

    Hwang, Jinkwang; Matsumoto, Kazuhiko; Orikasa, Yuki; Katayama, Misaki; Inada, Yasuhiro; Nohira, Toshiyuki; Hagiwara, Rika

    2018-02-01

    Maricite NaFePO4 (m-NaFePO4) was investigated as a positive electrode material for intermediate-temperature operation of sodium secondary batteries using ionic liquid electrolytes. Powdered m-NaFePO4 was prepared by a conventional solid-state method at 873 K and subsequently fabricated in two different conditions; one is ball-milled in acetone and the other is re-calcined at 873 K after the ball-milling. Electrochemical properties of the electrodes prepared with the as-synthesized m-NaFePO4, the ball-milled m-NaFePO4, and the re-calcined m-NaFePO4 were investigated in Na[FSA]-[C2C1im][FSA] (C2C1im+ = 1-ethyl-3-methylimidazolium, FSA- = bis(fluorosulfonyl)amide) ionic liquid electrolytes at 298 K and 363 K to assess the effects of temperature and particle size on their electrochemical properties. A reversible charge-discharge capacity of 107 mAh g-1 was achieved with a coulombic efficiency >98% from the 2nd cycle using the ball-milled m-NaFePO4 electrode at a C-rate of 0.1 C and 363 K. Electrochemical impedance spectroscopy using m-NaFePO4/m-NaFePO4 symmetric cells indicated that inactive m-NaFePO4 becomes an active material through ball-milling treatment and elevation of operating temperature. X-ray diffraction analysis of crystalline m-NaFePO4 confirmed the lattice contraction and expansion upon charging and discharging, respectively. These results indicate that the desodiation-sodiation process in m-NaFePO4 is reversible in the intermediate-temperature range.

  17. 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

    The present work was carried out on a series of heat-treatable aluminum-based aeronautical alloys containing various amounts of magnesium (Mg), iron (Fe), strontium (Sr) and beryllium (Be). Tensile test bars (dendrite arm spacing ~ 24mum) were solutionized for either 5 or 12 hours at 540°C, followed by quenching in warm water (60°C). Subsequently, these quenched samples were aged at 160°C for times up to 12 hours. Microstructural assessment was performed. All heat-treated samples were pulled to fracture at room temperature using a servo-hydraulic tensile testing machine. The results show that Be causes partial modification of the eutectic silicon (Si) particles similar to that reported for Mg addition. Addition of 0.8 wt.% Mg reduced the eutectic temperature by ~10°C. During solidification of alloys containing high levels of Fe and Mg, without Sr, a peak corresponding to the formation of a Be-Fe phase (Al8Fe2BeSi) was detected at 611°C. The Be-Fe phase precipitates in a script-like morphology. A new quinary eutectic-like reaction was observed to take place near the end of solidification of high Mg, high Fe, Be-containing alloys. This new reaction is composed mainly of fine particles of Si, Mg2Si, pi-Al 8Mg3FeSi6 and (Be-Fe) phases. The volume fraction of this reaction decreased with the addition of Sr. The addition of Be has a noticeable effect on decreasing the beta-phase length, or volume fraction, this effect may be limited by adding Sr. Beryllium addition also results in the precipitation of the beta-phase in a nodular form, which reduces the harmful effects of these intermetallics on the alloy mechanical properties. Increasing both Mg and Fe levels led to an increase in the amount of the pi-phase; increasing the iron content led to an increase in the volume fraction of the partially soluble beta- and pi-phases, while Mg2Si particles were completely dissolved. The beta-phase platelets were observed to undergo changes in their morphology due to the

  18. Electronic conductivity of solid and liquid (Mg, Fe)O computed from first principles

    Science.gov (United States)

    Holmström, E.; Stixrude, L.; Scipioni, R.; Foster, A. S.

    2018-05-01

    Ferropericlase (Mg, Fe)O is an abundant mineral of Earth's lower mantle and the liquid phase of the material was an important component of the early magma ocean. Using quantum-mechanical, finite-temperature density-functional theory calculations, we compute the electronic component of the electrical and thermal conductivity of (Mg0.75, Fe0.25)O crystal and liquid over a wide range of planetary conditions: 0-200 GPa, 2000-4000 K for the crystal, and 0-300 GPa, 4000-10,000 K for the liquid. We find that the crystal and liquid are semi-metallic over the entire range studied: the crystal has an electrical conductivity exceeding 103 S/m, whereas that of the liquid exceeds 104 S/m. Our results on the crystal are in reasonable agreement with experimental measurements of the electrical conductivity of ferropericlase once we account for the dependence of conductivity on iron content. We find that a harzburgite-dominated mantle with ferropericlase in combination with Al-free bridgmanite agrees well with electromagnetic sounding observations, while a pyrolitic mantle with a ferric-iron rich bridgmanite composition yields a lower mantle that is too conductive. The electronic component of thermal conductivity of ferropericlase with XFe = 0.19 is negligible (accounts for the high conductance that has been proposed to explain anomalies in Earth's nutation. The electrical conductivity of liquid ferropericlase exceeds that of liquid silica by more than an order of magnitude at conditions of a putative basal magma ocean, thus strengthening arguments that the basal magma ocean could have produced an ancient dynamo.

  19. On the distribution and evaluation of Na, Mg and Cl in leaves of selected halophytes

    Energy Technology Data Exchange (ETDEWEB)

    Pongrac, Paula; Vogel-Mikuš, Katarina; Regvar, Marjana [Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, SI-1000 Ljubljana (Slovenia); Kaligarič, Mitja [Department of Biology, Faculty of Natural Sciences and Mathematics, Koroška c. 160, SI-2000 Maribor (Slovenia); Vavpetič, Primož; Kelemen, Mitja; Grlj, Nataša [Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Shelef, Oren; Golan-Goldhirsh, Avi; Rachmilevitch, Shimon [French Associates Institute for Agriculture and Biotechnology of Drylands, The Jacob Blaustein Institutes for Desert Research (BIDR), Ben-Gurion University of the Negev, 84990 Midreshet Ben-Gurion (Israel); Pelicon, Primož, E-mail: primoz.pelicon@ijs.si [Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia)

    2013-07-01

    Diverse physiological, biochemical and morphological adaptations enable plants to survive in extreme saline environments where osmotic and ionic stresses limit growth and development. Halophytes are salt-tolerant plants that can withstand extraordinarily high levels of Na and Cl in their leaves. The tissue and cellular distribution patterns of salt ions can be linked to the underlying mechanisms of salt tolerance. Application of fast, reliable, multi-elemental and quantitative techniques such as micro-proton-induced X-ray emission (micro-PIXE) will significantly contribute to and accelerate studies of plant salt tolerance, especially as micro-PIXE also provides spatially resolved quantitative data for light elements, such as Na and Mg. The spatial concentration distributions of Na, Mg, Cl, K, P and S in leaves of four halophytes (Bassia indica, Atriplex prostrata, Spartina maritima and Limonium angustifolium) were determined using micro-PIXE, to study the salt-tolerance strategies of the selected halophytes. Different distribution patterns of the studied elements were seen in the leaves; however, in all four of these plant species, Na was excluded from photosynthetically active chlorophyl tissues. With the exception of L. angustifolium, Cl, P and S contents (representing chloride, phosphate and sulphate ionic forms, respectively) did not ensure charge balance in the leaves, which suggests other anionic compounds, such as nitrate and organic anions, have crucial roles in maintaining electroneutrality in these halophytes. By increasing soil salinisation worldwide, the possibility to reliably complement spatial distributions of Na, Mg, Cl, K, P and S with plant structural morphology will contribute significantly to our understanding of plant tolerance mechanisms at the tissue and cell levels. In addition, these kinds of studies are of particular value for designing crop plants with high salt tolerance and for the development of phytoremediation technologies.

  20. 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.

  1. Topotactic redox chemistry of NaFeAs in water and air and superconducting behavior with stoichiometry change.

    Energy Technology Data Exchange (ETDEWEB)

    Todorov, I.; Chung, D. Y.; Claus, H.; Malliakas, C. D.; Douvalis, A. P.; Bakas, T.; He, J.; Dravid, V. P.; Kanatzidis, M. G.; Materials Science Division; Northwestern Univ.; Univ. of Ioannina

    2010-07-13

    We report experimental evidence that shows superconductivity in NaFeAs occurs when it is Na deficient. The oxidation of NaFeAs progresses differently in water and in air. In water the material oxidizes slowly and slightly retaining the original anti-PbFCl structure. In air NaFeAs oxidizes topotactically quickly and extensively transforming to the ThCr{sub 2}Si{sub 2} structure type. Water acts as a mild oxidizing agent on the FeAs layer by extracting electrons and Na{sup +} cations from the structure, while oxidation in air is more extensive and leads to change in structure type from NaFeAs to NaFe{sub 2}As{sub 2}. The superconducting transition temperature moves dramatically during the oxidation process. Exposed to water for an extended time period NaFeAs shows a substantial increase in T{sub c} up to 25 K with contraction of unit cell volume. NaFe{sub 2}As{sub 2}, the air oxidized product, shows T{sub c} of 12 K. We report detailed characterization of the redox chemistry and transformation of NaFeAs in water and air using single crystal and powder X-ray diffraction, magnetization studies, transmission electron microscopy, Moessbauer spectroscopy, pOH and elemental analysis.

  2. Spectroscopy of {sup 18}Na: Bridging the two-proton radioactivity of {sup 19}Mg

    Energy Technology Data Exchange (ETDEWEB)

    Assie, M. [GANIL, CEA/DSM-CNRS/IN2P3, Caen (France); Institut de Physique Nucleaire, Universite Paris-Sud-11-CNRS/IN2P3, 91406 Orsay (France); Oliveira Santos, F. de, E-mail: oliveira@ganil.fr [GANIL, CEA/DSM-CNRS/IN2P3, Caen (France); Davinson, T. [SUPA School of Physics and Astronomy, The University of Edinburgh, Edinburgh EH9 3JZ (United Kingdom); Grancey, F. de [GANIL, CEA/DSM-CNRS/IN2P3, Caen (France); Achouri, L. [LPC/ENSICAEN, Blvd du Marechal Juin, 14050 Caen Cedex (France); Alcantara-Nunez, J. [Departamento de Fisica de Particulas, Universidade de Santiago de Compostela, E15782 (Spain); Al Kalanee, T.; Angelique, J.-C. [LPC/ENSICAEN, Blvd du Marechal Juin, 14050 Caen Cedex (France); Borcea, C.; Borcea, R. [Horia Hulubei National Institute for Physics and Nuclear Engineering, P.O. Box MG-6, 76900 Bucharest (Romania); Caceres, L. [GANIL, CEA/DSM-CNRS/IN2P3, Caen (France); Celikovic, I. [VINCA Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia); Chudoba, V. [Flerov Laboratory of Nuclear Reactions, JINR RU-141980 Dubna (Russian Federation); Institute of Physics, Silesian University in Opava, Bezrucovo nam. 13, 746 01 Opava (Czech Republic); Pang, D.Y. [GANIL, CEA/DSM-CNRS/IN2P3, Caen (France); Ducoin, C. [INFN - Sezione di Catania, Via S. Sofia 64, Catania 95123 (Italy); Fallot, M. [Subatech 4 rue Alfred Kastler, BP 20722, F-44307 Nantes Cedex 3 (France); Kamalou, O. [GANIL, CEA/DSM-CNRS/IN2P3, Caen (France); Kiener, J. [CSNSM, Universite Paris-Sud-11, CNRS/IN2P3, 91405 Orsay-Campus (France); Lam, Y. [CENBG CNRS/IN2P3 - Universite Bordeaux 1, Le Haut Vigneau, 33175 Gradignan cedex (France); and others

    2012-06-06

    The unbound nucleus {sup 18}Na, the intermediate nucleus in the two-proton radioactivity of {sup 19}Mg, was studied by the measurement of the resonant elastic scattering reaction H({sup 17}Ne,p){sup 17}Ne performed at 4 A.MeV using a radioactive beam from the SPIRAL Facility. Spectroscopic properties of the low-lying states were obtained in an R-matrix analysis of the excitation function.

  3. Accurate branching ratio measurements in 23Na(p,γ)24Mg

    International Nuclear Information System (INIS)

    Boydell, S.G.; Sargood, D.G.

    1975-01-01

    The reaction 23 Na(p,γ) 24 Mg has been investigated in the proton energy range 0.3-1.75 MeV. Gamma ray spectra were measured for 22 resonances with Ge(Li) detectors which were carefully calibrated for relative peak efficiencies. Allowance was made for the effect of anisotropies in all the emitted γ-rays. The spectra have been analysed to give branching ratios for bound and unbound levels. (author)

  4. Nuclear astrophysics with DRAGON at ISAC: the 21Na(p, γ)22Mg reaction

    International Nuclear Information System (INIS)

    D'Auria, J.M.

    2003-01-01

    The DRAGON facility at the new intense radioactive beams facility, ISAC, is now operational. It was built to perform studies of radiative alpha and proton capture reactions involving radioactive reactants, and of interest to nuclear astrophysics. The rate of the 21 Na(p, γ) 22 Mg reaction has been measured using inverse kinematics. Resonance strengths have been measured for states of importance for novae explosions. This report will summarize aspects of this study and its impact. (orig.)

  5. Hydrogen storage properties of Na-Li-Mg-Al-H complex hydrides

    International Nuclear Information System (INIS)

    Tang Xia; Opalka, Susanne M.; Laube, Bruce L.; Wu Fengjung; Strickler, Jamie R.; Anton, Donald L.

    2007-01-01

    Lightweight complex hydrides have attracted attention for their high storage hydrogen capacity. NaAlH 4 has been widely studied as a hydrogen storage material for its favorable reversible operating temperature and pressure range for automotive fuel cell applications. The increased understanding of NaAlH 4 has led to an expanded search for high capacity materials in mixed alkali and akali/alkaline earth alanates. In this study, promising candidates in the Na-Li-Mg-Al-H system were evaluated using a combination of experimental chemistry, atomic modeling, and thermodynamic modeling. New materials were synthesized using solid state and solution based processing methods. Their hydrogen storage properties were measured experimentally, and the test results were compared with theoretical modeling assessments

  6. 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.

  7. 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.

  8. 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

  9. Cross Section Measurements of the Reaction 23Na(p, γ)24Mg

    Science.gov (United States)

    Boeltzig, Axel; Deboer, Richard James; Macon, Kevin; Wiescher, Michael; Best, Andreas; Imbriani, Gianluca; Gyürky, György; Strieder, Frank

    2017-09-01

    The reaction 23Na(p, γ)24Mg can provide a link from the NeNa to the MgAl cycle in stellar burning and is therefore of interest in nuclear astrophysics. To determine the reaction rates at stellar temperatures, new cross section measurements at low proton energies have been performed recently, and further experiments are underway. The current cross section data implies that the reaction rate up to temperatures of 1 GK is determined by a few narrow resonances and direct capture. Complementary to these experimental efforts at low proton energies, cross section measurements at higher energies can help to constrain the direct capture and broad resonance contributions to the cross section and reduce the uncertainty of the extrapolation towards stellar energies. In this paper we report an experiment to measure the 23Na(p, γ)24Mg cross section with a solid target setup at the St. ANA 5U accelerator at the University of Notre Dame. The experiment and the current status of data analysis will be described. This work benefited from support by the National Science Foundation under Grant No. PHY-1430152 (JINA-CEE), the Nuclear Science Laboratory (NSL), the Istituto Nazionale di Fisica Nucleare (INFN), and the Gran Sasso Science Institute (GSSI).

  10. 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

  11. 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

  12. Interaction in the NaIn(MoO4)2 - AMoO4 (A = Mg, Mn) systems

    International Nuclear Information System (INIS)

    Kotova, I.Yu.; Kozhevnikova, N.M.

    2001-01-01

    The results of investigation into NaIn(MoO 4 ) 2 - AMoO 4 (A = Mg, Mn) quasibinary cross-sections by means of X-ray diffraction and differential thermal analysis are presented. Conducted researches revealed that compounds NaMg 3 In(MoO 4 ) and NaMn 3 In(MoO 4 ) melting incongruently at 990 Deg C and 940 Deg C accordingly were formed in the NaIn(MoO 4 ) - AMoO 4 (A = Mg, Mn) systems. The data of initiation of X-ray diffraction pattern of NaMg 3 In(MoO 4 ) 5 are presented. The temperature dependences of conductivity, dielectric permeability and tangent of dielectric losses indicative on ionic-electronic nature conductivity are determined. Activation energy of conductivity in the Mg - Mn row changes moderately - from 9.91 till 5.71 eV [ru

  13. 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 )

  14. Novel solid-state synthesis of α-Fe and Fe3O4 nanoparticles embedded in a MgO matrix

    Science.gov (United States)

    Schneeweiss, O.; Zboril, R.; Pizurova, N.; Mashlan, M.; Petrovsky, E.; Tucek, J.

    2006-01-01

    Thermally induced reduction of amorphous Fe2O3 nanopowder (2-3 nm) with nanocrystalline Mg (~20 nm) under a hydrogen atmosphere is presented as a novel route to obtain α-Fe and Fe3O4 magnetic nanoparticles dispersed in a MgO matrix. The phase composition, structural and magnetic properties, size and morphology of the nanoparticles were monitored by x-ray diffraction, 57Fe Mössbauer spectroscopy at temperatures of 24-300 K, transmission electron microscopy and magnetic measurements. Spherical magnetite nanoparticles prepared at a reaction temperature of 300 °C revealed a well-defined structure, with a ratio of tetrahedral to octahedral Fe sites of 1/2 being common for the bulk material. A narrow particle size distribution (20-30 nm) and high saturation magnetization (95 ± 5 A m2 kg-1) predispose the magnetite nanoparticles to various applications, including magnetic separation processes. The Verwey transition of Fe3O4 nanocrystals was found to be decreased to about 80 K. The deeper reduction of amorphous ferric oxide at 600 °C allows α-Fe (40-50 nm) nanoparticles to be synthesized with a coercive force of about 30 mT. They have a saturation magnetization 2.2 times higher than that of synthesized magnetite nanoparticles, which corresponds well with the ratio usually found for the pure bulk phases. The magnetic properties of α-Fe nanocrystals combined with the high chemical and thermal stability of the MgO matrix makes the prepared nanocomposite useful for various magnetic applications.

  15. 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.

  16. Optical and Luminescence Properties of β-NaFeO2 Nanoparticles

    Science.gov (United States)

    Singh, Sarbjit; Tangra, Ankush Kumar; Lotey, Gurmeet Singh

    2018-05-01

    β-NaFeO2 nanoparticles have been synthesized by sol-gel method and their morphological, structural and optical properties investigated. Transmission electron microscope study reveals that the size of the synthesis nanoparticles is 37 nm and they are possessing spherical symmetry. X-ray diffraction pattern shows the orthorhombic crystal structure of nanoparticles with space group Pn21 a. UV-visible spectra of β-NaFeO2 divulges that these nanoparticles have direct band gap 2.35 eV. The observed Fourier transform infrared spectroscopy spectra confirms the presence of Fe-Na bonding at 1074 cm-1. The photoluminescence study of these nanoparticles shows that these nanoparticles possesses various transition in the visible spectrum.

  17. 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.

  18. 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.

  19. 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...

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Synthesis and electrochemical properties of Na-rich Prussian blue analogues containing Mn, Fe, Co, and Fe for Na-ion batteries

    Science.gov (United States)

    Bie, Xiaofei; Kubota, Kei; Hosaka, Tomooki; Chihara, Kuniko; Komaba, Shinichi

    2018-02-01

    Electrochemical performance of Prussian blue analogues (PBAs) as positive electrode materials for non-aqueous Na-ion batteries is known to be highly dependent on their synthesis conditions according to the previous researches. Na-rich PBAs, NaxM[Fe(CN)6]·nH2O where M = Mn, Fe, Co, and Ni, are prepared via precipitation method under the same condition. The structure, chemical composition, morphology, valence of the transition metals, and electrochemical property of these samples are comparatively researched. The PBA with Mn shows large reversible capacity of 126 mAh g-1 in 2.0-4.2 V at a current density of 30 mA g-1 and the highest working voltage owning to high redox potential of Mn2+/3+ in MnN6 and Fe2+/3+ in FeC6. While, the PBA with Ni exhibits the best cyclability and rate performance though only 66 mAh g-1 is delivered. The significant differences in electrochemical behaviors of the PBAs originate from the various properties depending on different transition metals.

  5. The kinetic and mechanistic aspects of the oxidative dehydrogenation of ethane over Li/Na/MgO catalysts

    NARCIS (Netherlands)

    Swaan, H.M.; Swaan, H.M.; Toebes, A.; Toebes, A.; van Ommen, J.G.; Seshan, Kulathuiyer; Ross, J.R.H.; Ross, J.R.H.

    1992-01-01

    Kinetic and mechanistic aspects of the oxidative dehydrogenation of ethane catalysed by Li/MgO and Li/Na/MgO have been investigated. Initial rate measurements at 600°C; revealed that the Li/MgO catalyst produced C2H4, CO2, CO and H2 by parallel reactions whereas the sodium-promoted catalyst produced

  6. Zero thermal expansion in NaZn13-type La(Fe,Si)13 compounds.

    Science.gov (United States)

    Wang, Wei; Huang, Rongjin; Li, Wen; Tan, Jie; Zhao, Yuqiang; Li, Shaopeng; Huang, Chuanjun; Li, Laifeng

    2015-01-28

    A zero thermal expansion material in a pure form of NaZn13-type La(Fe,Si)13 was fabricated. Through optimizing the chemical composition, an isotropic zero thermal expansion material is achieved. The obtained materials exhibit a low expansion of |α| linear thermal expansion) over a broad temperature range (15-150 K). The present study indicates that the thermal expansion behavior of the NaZn13-type La(Fe,Si)13 compounds depends mainly on the content of Si element. This new material is desirable in many fields of industry as a reliable and low-cost zero thermal expansion material.

  7. 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.

  8. 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

  9. 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.

  10. 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 FeMg 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.

  11. Determination of Na, Cl, Ca, Mg, Mn and K in milk samples by activation analysis

    International Nuclear Information System (INIS)

    Kira, Carmen S.; Maihara, Vera A.

    2000-01-01

    In the present work cow milk samples distributed for Sao Paulo government institutions, by means of the 'Viva leite' programme, have been monitored. The concentrations of Ca, Cl, K, Mg, Mn and Na were determined in five milk samples and in three different kinds of commercial powder milk, by instrumental neutron activation. For quality control, the reference materials NIST whole milk powder and non fat milk powder were analysed. The results obtained are in the range of the concentrations mentioned in the literature for these elements. (author)

  12. Asymmetric fission of 47V induced by the 23Na+24Mg reaction

    International Nuclear Information System (INIS)

    Beck, C.; Djerroud, B.; Haas, F.; Freeman, R.M.; Hachem, A.; Heusch, B.; Morsad, A.; Vuillet-A-Cilles, M.; Sanders, S.J.

    1993-01-01

    The properties of fully energy-damped processes (deep-inelastic orbiting, fusion-evaporation, and fusion-fission processes) have been investigated in the nearly mass-symmetric entrance-channel 23 Na + 24 Mg reaction leading to the 47 V compound nucleus. By comparison with previous data for the mass-asymmetric 35 Cl + 12 C reaction forming the same compound system at the same excitation energy, no entrance-channel effects are observed in either the evaporation residue or the fusion-fission yields. This is in contrast to the situation with the 28 Si + 12 C and 24 Mg + 16 O reactions where an orbiting process is evident. The asymmetrical elemental distributions of the fusion-fission fragments of the massA=47 system are well described by a transition-state model that accounts for the spin and mass-asymmetry dependence of the fission saddle point

  13. Differential conductance measurements of low-resistance CoFeB/MgO/CoFeB magnetic tunnel junctions

    International Nuclear Information System (INIS)

    Nishioka, S.; Hamada, Y.V.; Matsumoto, R.; Mizuguchi, M.; Shiraishi, M.; Fukushima, A.; Kubota, H.; Nagahama, T.; Yuasa, S.; Maehara, H.; Nagamine, Y.; Tsunekawa, K.; Djayaprawira, D.D.; Watanabe, N.; Suzuki, Y.

    2007-01-01

    We measured differential conductance spectra of magnetic tunnel junctions (MTJs) with thin MgO barrier and low-resistance area product. The spectra of MTJs with MgO barrier thicker than 1.05 nm were essentially the same except for slight decrease of contributions from low-energy excitations, such as magnons. The spectra of MTJ with 1.01 nm MgO barrier were thoroughly different from the MTJs with thicker barrier. The result reveals that an MTJ with very thin MgO barrier thickness has different conduction characteristics from those with thicker MgO barriers

  14. Transient shallow reservoirs beneath small eruptive centres: Constraints from Mg-Fe interdiffusion in olivine

    Science.gov (United States)

    Morgado, E.; Parada, M. A.; Morgan, D. J.; Gutiérrez, F.; Castruccio, A.; Contreras, C.

    2017-11-01

    Small eruptive centres commonly have more primitive lavas than those associated with stratovolcanoes, an observation that has been taken to indicate a short magma residence in the crust relative to those reservoirs below stratovolcanoes. The Caburgua cones of the Andean Southern Volcanic Zone from a basaltic small eruptive centre where this can be tested. Here, we use MELTS simulations, and the available thermobarometry data to determine the conditions of olivine crystal rim formation and the Mg-Fe diffusion modelling to determine the magma residence times of those rims in the crust. Results yield timescales varying from a few days to dozens of days, and if freezing is to be avoided, can only be explained by some form of storage or slow transport through at least one shallow magma body. The longest durations of magma residence seen in the olivine rim zones are up to 471 days. These timescales are shorter than those estimated (decadal) from the nearby, more-differentiated, and well-established stratovolcano, Villarrica, which has a dominantly basaltic andesite composition. For Caburgua cones, we propose the existence of a transient reservoir, in contrast to a long-lived reservoir such as that inferred beneath the adjacent Villarrica stratovolcano.

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

    KAUST Repository

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

    2013-01-01

    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

  16. 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)

  17. KF-loaded mesoporous Mg-Fe bi-metal oxides: high performance transesterification catalysts for biodiesel production.

    Science.gov (United States)

    Tao, Guiju; Hua, Zile; Gao, Zhe; Zhu, Yan; Zhu, Yan; Chen, Yu; Shu, Zhu; Zhang, Lingxia; Shi, Jianlin

    2013-09-21

    Using newly developed mesoporous Mg-Fe bi-metal oxides as supports, a novel kind of high performance transesterification catalysts for biodiesel production has been synthesized. More importantly, the impregnation solvent was for the first time found to substantially affect the structures and catalytic performances of the resultant transesterification catalysts.

  18. 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.

  19. 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

  20. 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.

  1. 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).

  2. 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.

  3. Sodium intercalation in the phosphosulfate cathode NaFe2(PO4)(SO4)2

    Science.gov (United States)

    Ben Yahia, Hamdi; Essehli, Rachid; Amin, Ruhul; Boulahya, Khalid; Okumura, Toyoki; Belharouak, Ilias

    2018-04-01

    The compound NaFe2(PO4)(SO4)2 is successfully synthesized via a solid state reaction route and its crystal structure is determined using powder X-ray diffraction data. NaFe2(PO4)(SO4)2 phase is also characterized by cyclic voltammetry, galvanostatic cycling and electrochemical impedance spectroscopy. NaFe2(PO4)(SO4)2 crystallizes with the well-known NASICON-type structure. SAED and HRTEM experiments confirm the structural model, and no ordering between the PO4-3 and SO4-2 polyanions is detected. The electrochemical tests indicate that NaFe2(PO4)(SO4)2 is a 3 V sodium intercalating cathode. The electrical conductivity is relatively low (2.2 × 10-6 Scm-1 at 200 °C) and the obtained activation energy is ∼0.60eV. The GITT experiments indicate that the diffusivity values are in the range of 10-11-10-12 cm2/s within the measured sodium concentrations.

  4. Anoxic and Oxic Oxidation of Rocks Containing Fe(II)Mg-Silicates and Fe(II)-Monosulfides as Source of Fe(III)-Minerals and Hydrogen. Geobiotropy.

    Science.gov (United States)

    Bassez, Marie-Paule

    2017-12-01

    In this article, anoxic and oxic hydrolyses of rocks containing Fe (II) Mg-silicates and Fe (II)-monosulfides are analyzed at 25 °C and 250-350 °C. A table of the products is drawn. It is shown that magnetite and hydrogen can be produced during low-temperature (25 °C) anoxic hydrolysis/oxidation of ferrous silicates and during high-temperature (250 °C) anoxic hydrolysis/oxidation of ferrous monosulfides. The high-T (350 °C) anoxic hydrolysis of ferrous silicates leads mainly to ferric oxides/hydroxides such as the hydroxide ferric trihydroxide, the oxide hydroxide goethite/lepidocrocite and the oxide hematite, and to Fe(III)-phyllosilicates. Magnetite is not a primary product. While the low-T (25 °C) anoxic hydrolysis of ferrous monosulfides leads to pyrite. Thermodynamic functions are calculated for elementary reactions of hydrolysis and carbonation of olivine and pyroxene and E-pH diagrams are analyzed. It is shown that the hydrolysis of the iron endmember is endothermic and can proceed within the exothermic hydrolysis of the magnesium endmember and also within the exothermic reactions of carbonations. The distinction between three products of the iron hydrolysis, magnetite, goethite and hematite is determined with E-pH diagrams. The hydrolysis/oxidation of the sulfides mackinawite/troilite/pyrrhotite is highly endothermic but can proceed within the heat produced by the exothermic hydrolyses and carbonations of ferromagnesian silicates and also by other sources such as magma, hydrothermal sources, impacts. These theoretical results are confirmed by the products observed in several related laboratory experiments. The case of radiolyzed water is studied. It is shown that magnetite and ferric oxides/hydroxides such as ferric trihydroxide, goethite/lepidocrocite and hematite are formed in oxic hydrolysis of ferromagnesian silicates at 25 °C and 350 °C. Oxic oxidation of ferrous monosulfides at 25 °C leads mainly to pyrite and ferric oxides/hydroxides such as

  5. 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

  6. Determination of the Cl, Mg, Mn and Na, in samples of Tradescantia pallida

    International Nuclear Information System (INIS)

    Rossi, Joao Guilherme G.A.; Saiki, Mitiko

    2009-01-01

    The growing number of industries and automotive vehicles are causing the increase of the air pollution. Less expensive methodologies are been studying for the evaluation of these pollution levels. This work evaluates the concentrations of Cl, Mg, Mn and Na, present in the leaves of Tradescantia pallida viewing validation of the specie for use in the bio monitoring of the air pollution. Those leaves were collected and analysed using the short irradiation of the neutron activation analysis technique. The certified reference material INCT-MPH-2 Mixed Polish Herbs were analysed for the quality control of the results and presented very good accuracy, with relative errors less than 4.2 %, and good precision less than 8.7 %. The element concentrations (in μg g -1 ) obtained in the T. pallida samples analysed showed variation from 2324 to 33897 for Cl, from 3602 to 14450 for Mg, from 132 to 314 for Mn, and 21 to 615 for Na. Values obtained in the analyses of Tradescantia present great variability in the element concentrations. The short irradiation showed to be appropriated for determination of the elements studied in the bio monitoring of air pollution

  7. 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.

  8. 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)

  9. 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)

  10. 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.

  11. 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

  12. Magnetic properties of Mg12O12 nanocage doped with transition metal atoms (Mn, Fe, Co and Ni): DFT study

    Science.gov (United States)

    Javan, Masoud Bezi

    2015-07-01

    Binding energy of the Mg12O12 nanocage doped with transition metals (TM=Mn, Fe, Co and Ni) in endohedrally, exohedrally and substitutionally forms were studied using density functional theory with the generalized gradient approximation exchange-correlation functional along 6 different paths inside and outside of the Mg12O12 nanocage. The most stable structures were determined with full geometry optimization near the minimum of the binding energy curves of all the examined paths inside and outside of the Mg12O12 nanocage. The results reveal that for all stable structures, the Ni atom has a larger binding energy than the other TM atoms. It is also found that for all complexes additional peaks contributed by TM-3d, 4s and 4p states appear in the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) gap of the host MgO cluster. The mid-gap states are mainly due to the hybridization between TM-3d, 4s and 4p orbitals and the cage π orbitals. The magnetic moment of the endohedrally doped TM atoms in the Mg12O12 are preserved to some extent due to the interaction between the TM and Mg12O12 nanocage, in contrast to the completely quenched magnetic moment of the Fe and Ni atoms in the Mg11(TM)O12 complexes. Furthermore, charge population analysis shows that charge transfer occurs from TM atom to the cage for endohedrally and substitutionally doping.

  13. Ionic Conductivity of the Perovskites, NaMgF3MgF3 and KZnF3 at High Temperatures

    DEFF Research Database (Denmark)

    Andersen, N. H.; Kjems, Jørgen; Hayes, W.

    1985-01-01

    We have carried out a study of the ionic conductivity of NaMgF3, KMgF3 and KZnF3 up to temperatures close to the melting point. Our results, in contrast to previous reports in the literature, show no abnormal ionic conductivity at high temperatures. Care in interpretation of results is required...... because of surface electronic conduction....

  14. 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.

  15. Effect of CeLa addition on the microstructures and mechanical properties of Al-Cu-Mn-Mg-Fe alloy

    International Nuclear Information System (INIS)

    Du, Jiandi; Ding, Dongyan; Xu, Zhou; Zhang, Junchao; Zhang, Wenlong; Gao, Yongjin; Chen, Guozhen; Chen, Weigao; You, Xiaohua; Chen, Renzong; Huang, Yuanwei; Tang, Jinsong

    2017-01-01

    Development of high strength lithium battery shell alloy is highly desired for new energy automobile industry. The microstructures and mechanical properties of Al-Cu-Mn-Mg-Fe alloy with different CeLa additions were investigated through optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Rietveld refinement and tensile testing. Experimental results indicate that Al 8 Cu 4 Ce and Al 6 Cu 6 La phases formed due to CeLa addition. Addition of 0.25 wt.% CeLa could promote the formation of denser precipitation of Al 20 Cu 2 Mn 3 and Al 6 (Mn, Fe) phases, which improved the mechanical properties of the alloy at room temperature. However, up to 0.50 wt.% CeLa addition could promote the formation of coarse Al 8 Cu 4 Ce phase, Al 6 Cu 6 La phase and Al 6 (Mn, Fe) phase, which resulted in weakened mechanical properties. - Highlights: •Al-Cu-Mn-Mg-Fe alloys with different CeLa addition were fabricated through casting and rolling. •Al 8 Cu 4 Ce and Al 6 Cu 6 La phases formed after CeLa addition. •Addition of 0.25 wt.% CeLa promoted formation of denser precipitates of Al 20 Cu 2 Mn 3 and Al 6 (Mn, Fe). •Mechanical properties of the alloy was improved after 0.25 wt.% CeLa addition.

  16. Effects of Fragmented Fe Intermetallic Compounds on Ductility in Al-Si-Mg Alloys.

    Science.gov (United States)

    Kim, JaeHwang; Kim, DaeHwan

    2018-03-01

    Fe is intentionally added in order to form the Fe intermetallic compounds (Fe-IMCs) during casting. Field emission scanning electron microscope with energy dispersive spectrometer (EDS) was conducted to understand microstructural changes and chemical composition analyses. The needlelike Fe-IMCs based on two dimensional observation with hundreds of micro size are modified to fragmented particles with the minimum size of 300 nm through clod rolling with 80% thickness reduction. The ratio of Fe:Si on the fragmented Fe-IMCs after 80% reduction is close to 1:1, representing the β-Al5FeSi. The yield and tensile strengths are increased with increasing reduction rate. On the other hand, the elongation is decreased with the 40% reduction, but slightly increased with the 60% reduction. The elongation is dramatically increased over two times for the specimen of 80% reduction compared with that of the as-cast. Fracture behavior is strongly affected by the morphology and size of Fe-IMCs. The fracture mode is changed from brittle to ductile with the microstructure modification of Fe-IMCs.

  17. Emplacement of Widespread Fe/Mg Phyllosilicate Layer in West Margaritifer Terra, Mars

    Science.gov (United States)

    Seelos, K. D.; Maxwell, R. E.; Seelos, F. P.; Buczkowski, D.; Viviano-Beck, C. E.

    2017-12-01

    West Margaritifer Terra is located at the eastern end of Valles Marineris at the complex intersection of chaos terrains, cratered highlands, and multiple generations of outflow channels. Adjacent regions host layered phyllosilicates thought to indicate early Mars pedogenic and/or ground water-based alteration (e.g., Le Deit et al., 2012), and indeed, hydrologic modeling supports prolonged aqueous activity in the Noachian and Hesperian eras (Andrews-Hanna and Lewis, 2011). The remnant high-standing plateaus in West Margaritifer (0-15°S, 325-345°E) host numerous phyllosilicate-bearing outcrops as well and are the focus of this study. Here, we performed a systematic mapping and characterization of mineralogy and morphology of these deposits in order to assess similarity to other layered phyllosilicates and evaluate potential formation mechanisms. Utilizing multiple remote sensing datasets, we identified three types of phyllosilicate exposures distributed throughout the region: 1) along upper chaos fracture walls, 2) in erosional windows on the plains, and 3) in crater walls and ejecta. Outcrops are spectrally indicative of Fe/Mg smectite (most similar to saponite) and only rare, isolated occurrences of Al-phyllosilicate were observed. Morphologically, the layer is a few to 10 m thick, light-toned, polygonally fractured at decameter scales, and vertical subparallel banding is evident in places. These characteristics were used along with spatial distribution, elevation, and geologic context to evaluate 4 potential formation mechanisms: fluvio-lacustrine, pedogenesis, diagenesis, and hydrothermal alteration. We find that the widespread distribution and spectral homogeneity of the layer favors formation via groundwater alteration and/or pedogenic weathering. This is consistent with interpretations of similar layered phyllosilicates in NW Noachis Terra and the Valles Marineris plains to the west, and significantly extends the area over which these aqueous processes

  18. Passivation kinetics of Mg-Nd-Gd-Zn-Zr (EV31A and Mg-Y-Nd-Gd-Zr (WE43C in NaOH solutions

    Directory of Open Access Journals (Sweden)

    Jakraphan Ninlachart

    2017-09-01

    Full Text Available Passivation kinetics of two Mg-RE alloys, such as Mg-Nd-Gd-Zn-Zr (EV31A, and Mg-Y-Nd-Gd-Zr (WE43C were investigated in two different heat treated conditions (solution treated and overaged in 0.01 - 1.0 M NaOH solutions under potentiostatic conditions. Negative reaction order was observed in dilute NaOH which transitioned to positive values as the passivation time increased and in the 1 M NaOH as well. The passive layers showed platelet morphology and the size of the platelets decreased with increase in the NaOH concentration. The hydrogen evolution reaction (HER kinetics was not improved on the passive layer covered surface of the Mg-RE alloys in contrast to the improvements reported on the hydroxide covered pure magnesium. The electrochemical impedance increased with increase in the NaOH concentration in the solution treated condition of both Mg-RE alloys, whereas the overaged EV31A alloy showed a reverse trend. The passive layer of EV31A showed almost 100% higher charge carrier density than the film formed on the WE43C in the overaged condition. A better passivation behavior was observed in the solution treated condition than that in the overaged condition which could be attributed to the uniform distribution of the RE elements in the solution treated specimens. The WE43C alloy revealed better corrosion resistance in the alkaline solution than the EV31A alloy.

  19. 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

  20. Detailed investigation of Na2.24FePO4CO3 as a cathode material for Na-ion batteries

    Science.gov (United States)

    Huang, Weifeng; Zhou, Jing; Li, Biao; Ma, Jin; Tao, Shi; Xia, Dingguo; Chu, Wangsheng; Wu, Ziyu

    2014-01-01

    Na-ion batteries are gaining an increased recognition as the next generation low cost energy storage devices. Here, we present a characterization of Na3FePO4CO3 nanoplates as a novel cathode material for sodium ion batteries. First-principles calculations reveal that there are two paths for Na ion migration along b and c axis. In-situ and ex-situ Fe K-edge X-ray absorption near edge structure (XANES) point out that in Na3FePO4CO3 both Fe2+/Fe3+ and Fe3+/Fe4+ redox couples are electrochemically active, suggesting also the existence of a two-electron intercalation reaction. Ex-situ X-ray powder diffraction data demonstrates that the crystalline structure of Na3FePO4CO3 remains stable during the charging/discharging process within the range 2.0–4.55 V. PMID:24595232

  1. 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.

  2. High pressure structural investigation on alluaudites Na{sub 2}Fe{sub 3}(PO{sub 4}){sub 3}-Na{sub 2}FeMn{sub 2}(PO{sub 4}){sub 3} system

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Jing [Key Laboratory of Orogenic Belts and Crustal Evolution, MOE, School of Earth and Space Sciences, Peking University, Beijing 100871 (China); Huang, Weifeng [College of Engineering, Peking University, Beijing 100871 (China); Qin, Shan [Key Laboratory of Orogenic Belts and Crustal Evolution, MOE, School of Earth and Space Sciences, Peking University, Beijing 100871 (China); Wu, Xiang, E-mail: wuxiang@cug.edu.cn [State key laboratory of geological processes and mineral resources, China University of Geosciences, Wuhan 430074 (China)

    2017-03-15

    Alluaudites are promising electrochemical materials benefited from the open structure. Structural variations of alluaudites Na{sub 2}M{sub 3}(PO{sub 4}){sub 3} (M{sub 3}=Fe{sub 3}, Fe{sub 2}Mn and FeMn{sub 2}) system have been studied by synchrotron radiation X-ray diffraction combined with diamond anvil cell technique up to ~10 GPa at room temperature. No phase transition is observed. The excellent structural stability is mainly due to the flexible framework plus strong covalent P-O bond. Mn{sup 2+} instead of Fe can be described as Na{sup +}+2Fe{sup 2+}→Mn{sup 2+}+Fe{sup 3+}+□ where □ represents a lattice vacancy. The replacement of Fe with larger Mn{sup 2+} is equivalent to applying negative chemical pressure to the material. And it causes a more compressible b-axis, lattice expansion, structural compressibility and intensifies the core/electron-electron interactions of Fe. External pressure effect produces anisotropic lattice shrinkage. Structural considerations related to these variations and promising application prospects are discussed. - Graphical abstract: Figure 1 The crystal structure of alluaudites Na{sub 2}M{sub 3}(PO{sub 4}){sub 3} (M{sub 3}=Fe{sub 3}, Fe{sub 2}Mn and FeMn{sub 2}) projected along the c-axis. Alluaudites adopt a flexible framework plus strong covalent P-O bond, which contribute to excellent structural stability up to ~10 GPa. Mn{sup 2+} instead of Fe can be described as Na{sup ++}2Fe{sup 2+}→Mn{sup 2+}+Fe{sup 3+}+□ where □ represents a lattice vacancy, and it is equivalent to applying negative chemical pressure to the host. The substitution causes a more compressible b-axis, lattice expansion, structural compressibility and intensifies the core/electron-electron interactions of Fe.

  3. Effect of Fe3O4 addition on removal of ammonium by zeolite NaA.

    Science.gov (United States)

    Liu, Haibo; Peng, Shuchuan; Shu, Lin; Chen, Tianhu; Bao, Teng; Frost, Ray L

    2013-01-15

    Magnetic zeolite NaA with different Fe(3)O(4) loadings was prepared by hydrothermal synthesis based on metakaolin and Fe(3)O(4). The effect of added Fe(3)O(4) on the removal of ammonium by zeolite NaA was investigated by varying the Fe(3)O(4) loading, pH, adsorption temperature, initial concentration, adsorption time. Langmuir, Freundlich, and pseudo-second-order modeling were used to describe the nature and mechanism of ammonium ion exchange using both zeolite and magnetic zeolite. Thermodynamic parameters such as change in Gibbs free energy, enthalpy and entropy were calculated. The results show that all the selected factors affect the ammonium ion exchange by zeolite and magnetic zeolite, however, the added Fe(3)O(4) apparently does not affect the ion exchange performance of zeolite to the ammonium ion. Freundlich model provides a better description of the adsorption process than Langmuir model. Moreover, kinetic analysis indicates the exchange of ammonium on the two materials follows a pseudo-second-order model. Thermodynamic analysis makes it clear that the adsorption process of ammonium is spontaneous and exothermic. Regardless of kinetic or thermodynamic analysis, all the results suggest that no considerable effect on the adsorption of the ammonium ion by zeolite is found after the addition of Fe(3)O(4). According to the results, magnetic zeolite NaA can be used for the removal of ammonium due to the good adsorption performance and easy separation method from aqueous solution. Copyright © 2012 Elsevier Inc. All rights reserved.

  4. ELLERMAN BOMBS AT HIGH RESOLUTION. IV. VISIBILITY IN Na I AND Mg I

    Energy Technology Data Exchange (ETDEWEB)

    Rutten, R. J.; Rouppe van der Voort, L. H. M.; Vissers, G. J. M., E-mail: R.J.Rutten@uu.nl [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, N-0315 Oslo (Norway)

    2015-08-01

    Ellerman bombs are transient brightenings of the wings of the solar Balmer lines that mark reconnection in the photosphere. Ellerman noted in 1917 that he did not observe such brightenings in the Na i D and Mg i b lines. This non-visibility should constrain EB interpretation, but has not been addressed in published bomb modeling. We therefore test Ellerman’s observation and confirm it using high-quality imaging spectrometry with the Swedish 1-m Solar Telescope. However, we find a diffuse brightness in these lines that seems to result from prior EBs. We tentatively suggest this is a post-bomb hot-cloud phenomenon also found in recent EB spectroscopy in the ultraviolet.

  5. Interactions of Na+, K+, Mg2+, and Ca 2+ with benzene self-assembled monolayers

    DEFF Research Database (Denmark)

    Pedersen, Morten Rimmen; Matthiesen, Jesper; Bovet, Nicolas Emile

    2014-01-01

    that are most common in the natural world, namely, Na+, K+, Mg 2+, and Ca2+. Specifically, we investigated how these ions affect the interactions between surfaces covered by self-Assembled monolayers (SAMs) terminated with benzene molecules. We used a flat oxidized silicon substrate and an atomic force...... from X-ray photoelectron spectroscopy (XPS) allowed us to conclude that K+ binds in the benzene layers, creating a positive surface charge on the benzene-covered surfaces, thus leading to lower adhesion in KCl solutions than in pure water. Evidence suggested that Ca2+ does not bind to the surfaces...... measurements. The results of our studies clearly show that even a nonpolar, hydrophobic molecule, such as benzene, has a role to play in the behavior of aqueous solutions and that it interacts differently depending on which ions are present. Even ions from the same column in the periodic table behave...

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

    Directory of Open Access Journals (Sweden)

    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.

  7. 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.

  8. Chemistry of Frozen NaCl and MgSO4 Brines - Implications for Surface Expression of Europa's Ocean Composition

    Science.gov (United States)

    Johnson, P. V.; Hodyss, R. P.; Choukroun, M.; Vu, T. H.

    2015-12-01

    The composition of Europa's subsurface ocean is a critical determinant of its habitability, but current analysis of the ocean composition is limited to its expression on the Europan surface. While there is observational evidence indicating that ocean materials make their way to the surface, our understanding of the chemical processes that can alter this material under Europan surface conditions is limited. We present experimental data on the chemistry of mixed solutions of NaCl and MgSO4 as they are frozen to 100 K, replicating the conditions that may occur when subsurface ocean fluids are emplaced onto Europa's surface. Confocal micro-Raman spectroscopy is used to study the formation of salts during the freezing process, and the interaction of ions in the frozen brines. Our data indicate that mixed aqueous solutions of NaCl and MgSO4 form Na2SO4 and MgCl2 preferentially when frozen, rather than making NaCl and MgSO4 precipitates. The detection of epsomite (MgSO4Ÿ•7H2O) on Europa's surface may therefore imply an ocean composition relatively low in sodium, unless radiolytic chemistry converts MgCl2 to MgSO4 as suggested by Hand and Brown 2013 (ApJ 145 110). These results have important implications for the interpretation of remote sensing data of Europa's surface.

  9. 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.

  10. 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.

  11. Strain relaxation studies of the Fe3O4/MgO (100) heteroepitaxial system grown by magnetron sputtering

    International Nuclear Information System (INIS)

    Balakrishnan, K; Arora, S K; Shvets, I V

    2004-01-01

    Detailed strain relaxation studies of epitaxial magnetite, Fe 3 O 4 , films on MgO(100) substrates grown by magnetron sputtering reveal the accommodation of strain up to 600 nm thickness, a thickness far above the critical thickness (t c ) predicted by theoretical models. The results are in agreement with the suggestion that the excess strain in Fe 3 O 4 /MgO (100) heteroepitaxy is accommodated by the presence of antiphase boundaries. The compressive strain generated by the antiphase boundaries compensates for the tensile strain within the growth islands, allowing the film to remain fully coherent with the substrate. Contrary to earlier findings, magnetization decreases with an increase in the film thickness. This vindicates the view that the structure of the antiphase boundaries depends on the growth conditions

  12. Ocorrência de insetos na pitaia no município de Lavras-MG

    Directory of Open Access Journals (Sweden)

    Virna Braga Marques

    2012-04-01

    Full Text Available Devido às suas características de sabor doce e suave, polpa firme e repleta de sementes com ação laxante, as pitaias têm despertado interesse nos produtores por sua grande aceitação nos mercados consumidores. Diante do exposto, este trabalho visou identificar os visitantes florais, polinizadores e os insetos que causam danos aos cladódios e aos frutos de pitaia (Hylocereus undatus, no município de Lavras, MG. O trabalho foi conduzido em um pomar experimental e na coleção de frutas exóticas. As coletas foram realizadas duas etapas (diurna e noturna. Foi observado que a polinização cruzada de pitaia é realizada por abelha (Apis mellifera durante o dia e os insetos que causam maiores danos são formigas (Atta e Solenopsis e irapuá (Trigona spinipes no município de Lavras, MG.  É necessário que o produtor tenha cautela antes de utilizar medidas de controle, pois alguns insetos são benéficos para a polinização cruzada das plantas de pitaia e outros podem causar sérios danos nos cladódios, flores e frutos.

  13. 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.

  14. Co2FeAl based magnetic tunnel junctions with BaO and MgO/BaO barriers

    Directory of Open Access Journals (Sweden)

    J. Rogge

    2015-07-01

    Full Text Available We succeed to integrate BaO as a tunneling barrier into Co2FeAl based magnetic tunnel junctions (MTJs. By means of Auger electron spectroscopy it could be proven that the applied annealing temperatures during BaO deposition and afterwards do not cause any diffusion of Ba neither into the lower Heusler compound lead nor into the upper Fe counter electrode. Nevertheless, a negative tunnel magnetoresistance (TMR ratio of -10% is found for Co2FeAl (24 nm / BaO (5 nm / Fe (7 nm MTJs, which can be attributed to the preparation procedure and can be explained by the formation of Co- and Fe-oxides at the interfaces between the Heusler and the crystalline BaO barrier by comparing with theory. Although an amorphous structure of the BaO barrier seems to be confirmed by high-resolution transmission electron microscopy (TEM, it cannot entirely be ruled out that this is an artifact of TEM sample preparation due to the sensitivity of BaO to moisture. By replacing the BaO tunneling barrier with an MgO/BaO double layer barrier, the electric stability could effectively be increased by a factor of five. The resulting TMR effect is found to be about +20% at room temperature, although a fully antiparallel state has not been realized.

  15. 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.

  16. 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.

  17. Melting Behavior and Thermolysis of NaBH4−Mg(BH42 and NaBH4−Ca(BH42 Composites

    Directory of Open Access Journals (Sweden)

    Morten B. Ley

    2015-04-01

    Full Text Available The physical properties and the hydrogen release of NaBH4–Mg(BH42 and NaBH4−Ca(BH42 composites are investigated using in situ synchrotron radiation powder X-ray diffraction, thermal analysis and temperature programmed photographic analysis. The composite, xNaBH4–(1 − xMg(BH42, x = 0.4 to 0.5, shows melting/frothing between 205 and 220 °C. However, the sample does not become a transparent molten phase. This behavior is similar to other alkali-alkaline earth metal borohydride composites. In the xNaBH4–(1 − xCa(BH42 system, eutectic melting is not observed. Interestingly, eutectic melting in metal borohydrides systems leads to partial thermolysis and hydrogen release at lower temperatures and the control of sample melting may open new routes for obtaining high-capacity hydrogen storage materials.

  18. Structural and electrical characterization of BiFeO3-NaTaO3 multiferroic

    International Nuclear Information System (INIS)

    Mohanty, Suchismita; Choudhary, R.N.P.; Parida, B.N.; Padhee, R.

    2014-01-01

    Using a standard high-temperature solid-state reaction technique, polycrystalline samples of (Bi 1-x , Na x ) (Fe 1-x , Ta x ) O 3 (x = 0.0, 0.5) were prepared. The formation of the desired materials was confirmed by X-ray diffraction. The surface texture of the prepared materials recorded by scanning electron microscope exhibits a uniform grain distribution with small voids suggesting the formation of high-density pellet samples. The impedance and dielectric properties of the materials were investigated as a function of temperature and frequency. The relative dielectric constant and loss tangent of BiFeO 3 decrease on addition of NaTaO 3 (x = 0.5). The effect of addition of NaTaO 3 on grain and grain boundary contributions in the resistive and capacitive components of BiFeO 3 was studied using complex impedance spectroscopy. The value of activation energy due to both grain and grain boundary of both the samples is nearly same. The nature of variation of dc conductivity confirms the Arrhenius behavior of the materials. Study of frequency dependence of ac conductivity suggests that the materials obey Jonscher's universal power law and the presence of ionic conductivity. (orig.)

  19. 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.

  20. 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.

  1. 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)

  2. Effect of CeLa addition on the microstructures and mechanical properties of Al-Cu-Mn-Mg-Fe alloy

    Energy Technology Data Exchange (ETDEWEB)

    Du, Jiandi [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Ding, Dongyan, E-mail: dyding@sjtu.edu.cn [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Xu, Zhou; Zhang, Junchao; Zhang, Wenlong [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Gao, Yongjin; Chen, Guozhen; Chen, Weigao; You, Xiaohua [Huafon NLM Al Co., Ltd, Shanghai 201506 (China); Chen, Renzong; Huang, Yuanwei; Tang, Jinsong [Shanghai Huafon Materials Technology Institute, Shanghai 201203 (China)

    2017-01-15

    Development of high strength lithium battery shell alloy is highly desired for new energy automobile industry. The microstructures and mechanical properties of Al-Cu-Mn-Mg-Fe alloy with different CeLa additions were investigated through optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Rietveld refinement and tensile testing. Experimental results indicate that Al{sub 8}Cu{sub 4}Ce and Al{sub 6}Cu{sub 6}La phases formed due to CeLa addition. Addition of 0.25 wt.% CeLa could promote the formation of denser precipitation of Al{sub 20}Cu{sub 2}Mn{sub 3} and Al{sub 6}(Mn, Fe) phases, which improved the mechanical properties of the alloy at room temperature. However, up to 0.50 wt.% CeLa addition could promote the formation of coarse Al{sub 8}Cu{sub 4}Ce phase, Al{sub 6}Cu{sub 6}La phase and Al{sub 6}(Mn, Fe) phase, which resulted in weakened mechanical properties. - Highlights: •Al-Cu-Mn-Mg-Fe alloys with different CeLa addition were fabricated through casting and rolling. •Al{sub 8}Cu{sub 4}Ce and Al{sub 6}Cu{sub 6}La phases formed after CeLa addition. •Addition of 0.25 wt.% CeLa promoted formation of denser precipitates of Al{sub 20}Cu{sub 2}Mn{sub 3} and Al{sub 6}(Mn, Fe). •Mechanical properties of the alloy was improved after 0.25 wt.% CeLa addition.

  3. Distribution of major elements (Na, K, Ca, Mg in the various anatomical parts of Fadama crops in Ekiti State, Nigeria

    Directory of Open Access Journals (Sweden)

    E.I. Adeyeye

    2005-12-01

    Full Text Available Levels of sodium, potassium, calcium and magnesium were determined in plant organs (bud, flowers, fruit, seed, leaves, stems, roots, cobs, styles, shaft, grains and efflorescences of three Fadama farms located in Ifaki-Ekiti, Ado-Ekiti and Ikere-Ekiti of Ekiti State, Nigeria. The highest levels of Mg, K, Na and Ca were obtained in the bud of Hibiscus esculentus with respective values (ppm dry weight, ppm DW of 4397, 2983, 3928 and 1622; this was closely followed by their levels in Lycopersicon esculentum root: Mg (2734, K (1079, Na (2111 and Ca (678. The levels of all the elements were highly varied in the anatomical parts of each plant and between the various plants. The index of bioaccumulation (ratio in plants/soil was recorded for all the elements with all values falling within 1-101 showing that the degree of accumulation was intensive. The overall levels of the elements were Mg > Na > K > Ca.

  4. 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

  5. Graphitic encapsulation of MgO and Fe3C nanoparticles in the reaction of iron pentacarbonyl with magnesium

    International Nuclear Information System (INIS)

    Dyjak, Sławomir; Cudziło, Stanisław; Polański, Marek; Budner, Bogusław; Bystrzycki, Jerzy

    2013-01-01

    A simple method to produce highly ordered carbon nanostructures by combustion synthesis is presented. Graphite-encapsulated magnesium oxide, iron carbide nanoparticles and carbon nanobelts were synthesized by the one-step reduction of iron pentacarbonyl with magnesium. High-resolution transmission electron microscopy analysis of the products revealed nanocrystalline MgO and Fe 3 C particles surrounded by a well-crystallized, tight graphite film. The possible formation mechanism is presented and discussed. - Highlights: • We present a simple method to produce highly ordered carbon nanostructures by combustion synthesis. • The cubic MgO particles are completely coated by tight graphitic shells. • The mechanism of formation a distant carbon film on MgO surface has been discussed. • The presented method can be applied to synthesis of other core-shell structures

  6. 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

  7. First-principles investigation of the very large perpendicular magnetic anisotropy at Fe | MgO and Co | MgO interfaces

    KAUST Repository

    Yang, H. X.; Chshiev, M.; Dieny, B.; Lee, J. H.; Manchon, Aurelien; Shin, K. H.

    2011-01-01

    The perpendicular magnetic anisotropy (PMA) arising at the interface between ferromagnetic transition metals and metallic oxides was investigated via first-principles calculations. In this work very large values of PMA, up to 3 erg/cm2, at Fe|MgO interfaces are reported, in agreement with recent experiments. The origin of PMA is attributed to overlap between O-pz and transition metal dz2 orbitals hybridized with dxz(yz) orbitals with stronger spin-orbit coupling-induced splitting around the Fermi level for perpendicular magnetization orientation. Furthermore, it is shown that the PMA value weakens in the case of over- or underoxidation due to the fact that oxygen pz and transition metal dz2 orbital overlap is strongly affected by disorder, in agreement with experimental observations in magnetic tunnel junctions.

  8. First-principles investigation of the very large perpendicular magnetic anisotropy at Fe | MgO and Co | MgO interfaces

    KAUST Repository

    Yang, H. X.

    2011-08-01

    The perpendicular magnetic anisotropy (PMA) arising at the interface between ferromagnetic transition metals and metallic oxides was investigated via first-principles calculations. In this work very large values of PMA, up to 3 erg/cm2, at Fe|MgO interfaces are reported, in agreement with recent experiments. The origin of PMA is attributed to overlap between O-pz and transition metal dz2 orbitals hybridized with dxz(yz) orbitals with stronger spin-orbit coupling-induced splitting around the Fermi level for perpendicular magnetization orientation. Furthermore, it is shown that the PMA value weakens in the case of over- or underoxidation due to the fact that oxygen pz and transition metal dz2 orbital overlap is strongly affected by disorder, in agreement with experimental observations in magnetic tunnel junctions.

  9. 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

  10. Reversible hydrogen storage by NaAlH4 confined within a titanium-functionalized MOF-74(Mg) nanoreactor.

    Science.gov (United States)

    Stavila, Vitalie; Bhakta, Raghunandan K; Alam, Todd M; Majzoub, Eric H; Allendorf, Mark D

    2012-11-27

    We demonstrate that NaAlH(4) confined within the nanopores of a titanium-functionalized metal-organic framework (MOF) template MOF-74(Mg) can reversibly store hydrogen with minimal loss of capacity. Hydride-infiltrated samples were synthesized by melt infiltration, achieving loadings up to 21 wt %. MOF-74(Mg) possesses one-dimensional, 12 Å channels lined with Mg atoms having open coordination sites, which can serve as sites for Ti catalyst stabilization. MOF-74(Mg) is stable under repeated hydrogen desorption and hydride regeneration cycles, allowing it to serve as a "nanoreactor". Confining NaAlH(4) within these pores alters the decomposition pathway by eliminating the stable intermediate Na(3)AlH(6) phase observed during bulk decomposition and proceeding directly to NaH, Al, and H(2), in agreement with theory. The onset of hydrogen desorption for both Ti-doped and undoped nano-NaAlH(4)@MOF-74(Mg) is ∼50 °C, nearly 100 °C lower than bulk NaAlH(4). However, the presence of titanium is not necessary for this increase in desorption kinetics but enables rehydriding to be almost fully reversible. Isothermal kinetic studies indicate that the activation energy for H(2) desorption is reduced from 79.5 kJ mol(-1) in bulk Ti-doped NaAlH(4) to 57.4 kJ mol(-1) for nanoconfined NaAlH(4). The structural properties of nano-NaAlH(4)@MOF-74(Mg) were probed using (23)Na and (27)Al solid-state MAS NMR, which indicates that the hydride is not decomposed during infiltration and that Al is present as tetrahedral AlH(4)(-) anions prior to desorption and as Al metal after desorption. Because of the highly ordered MOF structure and monodisperse pore dimensions, our results allow key template features to be identified to ensure reversible, low-temperature hydrogen storage.

  11. On the roles of the dopants in LiF: Mg,Cu,Na,Si thermoluminescent material

    International Nuclear Information System (INIS)

    Lee, J. I.; Kim, J. L.; Chang, S. Y.; Chung, K. S.; Choe, H. S.

    2005-01-01

    In this paper, some results of the study on the roles of the dopants in the LiF:Mg,Cu,Na,Si thermoluminescent (TL) material that was developed at the Korea Atomic Energy Research Inst. for radiation protection are presented. Although there have been many studies to investigate the roles of the dopants in LiF:Mg,Cu,P TL material in the TL process, there are some discrepancies in the understanding of the roles of Cu and P between various researchers. In case of LiF:Mg,Cu,Na,Si TL material, there are a few studies on the roles of the dopants. Three kinds of samples in each of which one dopant is excluded, and the optimised sample, were prepared for this study. The measurements and analysis of the three-dimensional TL spectra, based on the temperature, wavelength and intensity, and the glow curves for those samples are used in this study. The results show that Mg plays a role in the trapping of the charge carriers and Cu plays a role in the luminescence recombination process; however, the effect of Na and Si on the glow curve structure and the TL emission spectra is much less than that of Mg and Cu. It is considered that Na and Si each plays a role in the improvement of the luminescence efficiency. (authors)

  12. Dielectric behaviour of MgFe2O4 prepared from chemically ...

    Indian Academy of Sciences (India)

    Unknown

    dielectric loss factor. 1. Introduction ... such production of ferrites in year 2005 would be of about. 10,50,000 MTPY. ... factors such as method of preparation, chemical compo- sition, and ..... (VII) Low content of polarizable Fe2+ ions on the octa-.

  13. Mechanical alloying in Fe2O3-MO (M: Zn, Ni, Cu, Mg) systems

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Gerward, Leif; Mørup, Steen

    1999-01-01

    of MFe2O4 ferrites are critically discussed. No significant with respect to ferrite formation rates was observed in open and closed containers used here. In the Fe2O3/ZnO system, a single ferrite phase can be synthesized but in other systems no significant amounts of ferrites are formed by high...

  14. Q value of the superallowed decay of 22Mg and the calibration of the 21Na(p,γ) experiment

    International Nuclear Information System (INIS)

    Savard, G.; Clark, J.A.; Wang, J.C.; Buchinger, F.; Crawford, J.E.; Gulick, S.; Lee, J.K.P.; Hardy, J.C.; Iacob, V.E.; Hecht, A.A.; Levand, A.F.; Lundgren, B.F.; Scielzo, N.D.; Tanihata, I.; Trimble, W.; Zhou, Z.; Sharma, K.S.; Wang, Y.; Towner, I.S.

    2004-01-01

    The masses of the radioactive nuclei 22 Mg and 22 Na have been measured with the Canadian Penning trap on-line mass spectrometer to a precision of 3x10 -8 and 1x10 -8 , respectively. A Q EC value of 4124.39(73) keV for the superallowed β decay of 22 Mg is obtained from the difference of these two masses. With this precise Q value, the Ft value for this decay is determined with improved precision and is found to be consistent with the existing precision data set of superallowed Fermi emitters. This provides an important test of the isospin symmetry-breaking corrections. If the mass of 22 Mg determined here is used in the calibration of a recent 21 Na(p,γ) 22 Mg measurement, part of the discrepancy observed in that measurement is removed

  15. Glow-peak stability in 6LiF:Mg, Ti (TLD-600) exposed to a Fe-ion beam

    International Nuclear Information System (INIS)

    Yasuda, Hiroshi

    2001-01-01

    The stability of glow peaks in 6 LiF:Mg, Ti (TLD-600) exposed to a high-energy Fe-ion beam was examined in comparison to 137 Cs γ-ray irradiation under changing annealing conditions. The peak areas induced by the Fe ions were much smaller than those by γ-rays. The sizes and positions of peaks 3-5 in Fe-ion irradiated samples were hardly changed after post-annealing at 100 deg C x 30 min, regardless of the pre-annealing conditions (fast quenching or subsequent pre-annealing at 100 deg C x 2 h). Whereas, the peaks in γ-ray irradiated samples were notably affected by post-annealing; the peak positions and peak-area sizes changed in different ways depending on the pre-annealing conditions. The effects of post-annealing on peak 6 were identical for Fe ions and γ-rays. These facts suggest that peaks 3-5 in TLD-600 comprised both stable and unstable luminescent centers, and that the latter part would be easily depleted in highly dense ionization. (author)

  16. Non-specific binding of Na+ and Mg2+ to RNA determined by force spectroscopy methods

    Science.gov (United States)

    Bizarro, C. V.; Alemany, A.; Ritort, F.

    2012-01-01

    RNA duplex stability depends strongly on ionic conditions, and inside cells RNAs are exposed to both monovalent and multivalent ions. Despite recent advances, we do not have general methods to quantitatively account for the effects of monovalent and multivalent ions on RNA stability, and the thermodynamic parameters for secondary structure prediction have only been derived at 1M [Na+]. Here, by mechanically unfolding and folding a 20 bp RNA hairpin using optical tweezers, we study the RNA thermodynamics and kinetics at different monovalent and mixed monovalent/Mg2+ salt conditions. We measure the unfolding and folding rupture forces and apply Kramers theory to extract accurate information about the hairpin free energy landscape under tension at a wide range of ionic conditions. We obtain non-specific corrections for the free energy of formation of the RNA hairpin and measure how the distance of the transition state to the folded state changes with force and ionic strength. We experimentally validate the Tightly Bound Ion model and obtain values for the persistence length of ssRNA. Finally, we test the approximate rule by which the non-specific binding affinity of divalent cations at a given concentration is equivalent to that of monovalent cations taken at 100-fold concentration for small molecular constructs. PMID:22492710

  17. 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

  18. 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

  19. 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.

  20. Superconducting instabilities and quasipartical interference in the LiFeAs and Co-doped NaFeAs iron-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Altenfeld, Dustin; Ahn, Felix; Eremin, Ilya [Institut fuer Theoretische Physik III, Ruhr-Universitaet Bochum, D-44801 Bochum (Germany); Borisenko, Sergey [Leibniz-Institute for Solid State Research, IFW-Dresden, D-01171 Dresden (Germany)

    2015-07-01

    We analyze and compare the structure of the pairing interaction and superconducting gaps in LiFeAs and Co-doped NaFeAs by using the ten-orbital tight-binding model, derived from ab initio LDA calculations with hopping parameters extracted from the fit to ARPES experiments. We discuss the phase diagram and experimental probes to determine the structure of the superconducting gap in these systems with special emphasis on the quasiparticle interference, computed using the T-matrix approximation. In particular, we analyze how the superconducting state with opposite sign of the gaps on the two inner hole pockets in LiFeAs evolve upon changing the parameters towards NaFeAs compound.

  1. Maximum magnitude in bias-dependent spin accumulation signals of CoFe/MgO/Si on insulator devices

    International Nuclear Information System (INIS)

    Ishikawa, M.; Sugiyama, H.; Inokuchi, T.; Tanamoto, T.; Saito, Y.; Hamaya, K.; Tezuka, N.

    2013-01-01

    We study in detail how the bias voltage (V bias ) and interface resistance (RA) depend on the magnitude of spin accumulation signals (|ΔV| or |ΔV|/I, where I is current) as detected by three-terminal Hanle measurements in CoFe/MgO/Si on insulator (SOI) devices with various MgO layer thicknesses and SOI carrier densities. We find the apparent maximum magnitude of spin polarization as a function of V bias and the correlation between the magnitude of spin accumulation signals and the shape of differential conductance (dI/dV) curves within the framework of the standard spin diffusion model. All of the experimental results can be explained by taking into account the density of states (DOS) in CoFe under the influence of the applied V bias and the quality of MgO tunnel barrier. These results indicate that it is important to consider the DOS of the ferromagnetic materials under the influence of an applied V bias and the quality of tunnel barrier when observing large spin accumulation signals in Si

  2. MODELS FOR METAL-POOR STARS WITH ENHANCED ABUNDANCES OF C, N, O, Ne, Na, Mg, Si, S, Ca, AND Ti, IN TURN, AT CONSTANT HELIUM AND IRON ABUNDANCES

    Energy Technology Data Exchange (ETDEWEB)

    VandenBerg, Don A.; Dotter, Aaron [Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, Victoria, B.C. V8W 3P6 (Canada); Bergbusch, Peter A. [Department of Physics, University of Regina, Regina, Saskatchewan S4S 0A2 (Canada); Ferguson, Jason W. [Department of Physics, Wichita State University, Wichita, KS 67260-0032 (United States); Michaud, Georges; Richer, Jacques [Departement de Physique, Universite de Montreal, Montreal, Quebec H3C 3J7 (Canada); Proffitt, Charles R., E-mail: vandenbe@uvic.ca, E-mail: Aaron.Dotter@gmail.com, E-mail: pbergbusch@accesscomm.ca, E-mail: proffitt@stsci.edu, E-mail: Jason.Ferguson@wichita.edu, E-mail: michaudg@astro.umontreal.ca, E-mail: jacques.richer@umontreal.ca [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2012-08-10

    Recent work has shown that most globular clusters have at least two chemically distinct components, as well as cluster-to-cluster differences in the mean [O/Fe], [Mg/Fe], and [Si/Fe] ratios at similar [Fe/H] values. In order to investigate the implications of variations in the abundances of these and other metals for H-R diagrams and predicted ages, grids of evolutionary sequences have been computed for scaled solar and enhanced {alpha}-element metal abundances, and for mixtures in which the assumed [m/Fe] value for each of the metals C, N, O, Ne, Na, Mg, Si, S, Ca, and Ti has been increased, in turn, by 0.4 dex at constant [Fe/H]. These tracks, together with isochrones for ages from Almost-Equal-To 5 to 14 Gyr, have been computed for -3.0 {<=} [Fe/H] {<=}-0.6, with helium abundances Y = 0.25, 0.29, and 0.33 at each [Fe/H] value, using upgraded versions of the Victoria stellar structure program and the Regina interpolation code, respectively. Turnoff luminosity versus age relations from isochrones are found to depend almost entirely on the importance of the CNO cycle, and thereby mainly on the abundance of oxygen. Since C, N, and O, as well as Ne and S, do not contribute significantly to the opacities at low temperatures and densities, variations in their abundances do not impact the predicted T{sub eff} scale of red giants. The latter is a strong function of the abundances of only Mg and Si (and Fe, possibly to a lesser extent) because they are so abundant and because they are strong sources of opacity at low temperatures. For these reasons, Mg and Si also have important effects on the temperatures of main-sequence stars. Due to their low abundances, Na, Ca, and Ti are of little consequence for stellar models. The effects of varying the adopted solar metals mixture and the helium abundance at a fixed [Fe/H] are also briefly discussed.

  3. 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.

  4. Dynamic Spin-Lattice Coupling and Nematic Fluctuations in NaFeAs

    Directory of Open Access Journals (Sweden)

    Yu Li

    2018-06-01

    Full Text Available We use inelastic neutron scattering to study acoustic phonons and spin excitations in single crystals of NaFeAs, a parent compound of iron-pnictide superconductors. NaFeAs exhibits a tetragonal-to-orthorhombic structural transition at T_{s}≈58  K and a collinear antiferromagnetic order at T_{N}≈45  K. While longitudinal and out-of-plane transverse acoustic phonons behave as expected, the in-plane transverse acoustic phonons reveal considerable softening on cooling to T_{s} and then harden on approaching T_{N} before saturating below T_{N}. In addition, we find that spin-spin correlation lengths of low-energy magnetic excitations within the FeAs layer and along the c axis increase dramatically below T_{s} and show a weak anomaly across T_{N}. These results suggest that the electronic nematic phase present in the paramagnetic tetragonal phase is closely associated with dynamic spin-lattice coupling, possibly arising from the one-phonon–two-magnon mechanism.

  5. 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.

  6. Comparison of interface structure of BCC metallic (Fe, V and Nb) films on MgO (100) substrate

    Energy Technology Data Exchange (ETDEWEB)

    Du, J.L. [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Zhang, L.Y. [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an, 710049 (China); Fu, E.G., E-mail: efu@pku.edu.cn [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Ding, X., E-mail: dingxd@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an, 710049 (China); Yu, K.Y., E-mail: kyyu@cup.edu.cn [Department of Materials Science and Engineering, China University of Petroleum, Beijing 102249 (China); Wang, Y.G. [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Wang, Y.Q.; Baldwin, J.K. [Experimental Physical Sciences Directorate, Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Wang, X.J. [State Key Laboratory of Advanced Optical Communication Systems and Networks, Peking University, Beijing 100871 (China); Xu, P. [Department of Chemistry, Harbin Institute of Technology, Harbin, Heilongjiang, 150001 (China)

    2017-07-15

    Highlights: • The difference of BCC metal/MgO(100) interface configuration with various lattice mismatches is identified by experiments and simulations in terms of dislocations and work of separation. • The strength of bonds along interface is found to be the fundamental factor to determine the interface configurations between BCC metal and MgO substrate. • The combination of experiments and simulations shows that the O-atop model is the actual match type between BCC metal and MgO substrate. - Abstract: This study systematically investigates the interface structure of three body-centered-cubic (BCC) metallic (Fe, V and Nb) films grown on MgO(100) substrates through experiments and simulations. Orientation relationships of their interfaces with the different lattice mismatches exhibit cube-on-cube configurations. The misfit dislocations at these three interfaces exhibit different characteristics. High resolution TEM (HRTEM), combined with first principle calculations, demonstrates the O-atop match type between metal atoms and MgO substrates for the first time. The fundamental mechanism in determining the interface configuration is discussed in terms of the work of separation and delocalization of atomic charge density.

  7. Equilibrium between (Li,Na,K,Mg)-carbonate melt, gaseous CO

    NARCIS (Netherlands)

    Velden, P.F. van

    1967-01-01

    Considerable amounts of MgCO3 may appear in alkali metal carbonate melts in contact with MgO and carbon dioxide gas. The equilibrium between dissolved MgCO3, MgO and carbon dioxide gas has been studied. The results satisfactorily obey thermodynamic theory based upon a melt

  8. 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

  9. Crystal structures and magnetic properties of iron (III)-based phosphates: Na4NiFe(PO4)3 and Na2Ni2Fe(PO4)3

    International Nuclear Information System (INIS)

    Essehli, Rachid; Bali, Brahim El; Benmokhtar, Said; Bouziane, Khalid; Manoun, Bouchaib; Abdalslam, Mouner Ahmed; Ehrenberg, Helmut

    2011-01-01

    Graphical abstract: A perspective view of the Na 2 Ni 2 Fe(PO 4 ) 3 structure along the [0 0 1] direction. Both compounds seem to exibit antiferromagnetic interactions between magnetic entities at low temperature. Display Omitted Research highlights: → Nasicon and Alluaudite compounds, Iron(III)-based phosphates, Crystal structures of Na 4 NiFe(PO 4 ) 3 and Na 2 Ni 2 Fe(PO 4 ) 3 . → Magnetism behaviours of Na 4 NiFe(PO 4 ) 3 and Na 2 Ni 2 Fe(PO 4 ) 3 . → Antiferromagnetism interactions. → Mossbauer spectroscopy. - Abstract: Crystal structures from two new phosphates Na 4 NiFe(PO 4 ) 3 (I) and Na 2 Ni 2 Fe(PO 4 ) 3 (II) have been determined by single crystal X-ray diffraction analysis. Compound (I) crystallizes in a rhombohedral system (S. G: R-3c, Z = 6, a = 8.7350(9) A, c = 21.643(4) A, R 1 = 0.041, wR 2 =0.120). Compound (II) crystallizes in a monoclinic system (S. G: C2/c, Z = 4, a = 11.729(7) A, b = 12.433(5) A, c = 6.431(2) A, β = 113.66(4) o , R 1 = 0.043, wR 2 =0.111). The three-dimensional structure of (I) is closely related to the Nasicon structural type, consisting of corner sharing [(Ni/Fe)O 6 ] octahedra and [PO 4 ] tetrahedra forming [NiFe(PO 4 ) 3 ] 4+ units which align in chains along the c-axis. The Na + cations fill up trigonal antiprismatic sites within these chains. The crystal structure of (II) belongs to the alluaudite type. Its open framework results from [Ni 2 O 10 ] units of edge-sharing [NiO 6 ] octahedra, which alternate with [FeO 6 ] octahedra that form infinite chains. Coordination of these chains yields two distinct tunnels in which site Na + . The magnetization data of compound (I) reveal antiferromagnetic (AFM) interactions by the onset of deviations from a Curie-Weiss behaviour at low temperature as confirmed by Moessbauer measurements performed at 4.2 K. The corresponding temperature dependence of the reciprocal susceptibility χ -1 follows a typical Curie-Weiss behaviour for T > 105 K. A canted AFM state is proposed for

  10. Orthorhombic polar Nd-doped BiFeO{sub 3} thin film on MgO substrate

    Energy Technology Data Exchange (ETDEWEB)

    Leontyev, I N; Janolin, P-E; Dkhil, B [Laboratoire Structures, Proprietes et Modelisation des Solides, UMR CNRS-Ecole Centrale Paris, 92295 Chatenay-Malabry Cedex (France); Yuzyuk, Yu I [Faculty of Physics, Southern Federal University, Zorge 5, Rostov-on-Don 344090 (Russian Federation); El-Marssi, M [Laboratoire de Physique de la Matiere Condensee, Universite de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens (France); Chernyshov, D; Dmitriev, V [Swiss-Norwegian Beam Lines at ESRF, Boite Postale 220, F-38043 Grenoble (France); Golovko, Yu I; Mukhortov, V M, E-mail: i.leontiev@rambler.ru [Southern Scientific Center RAS, Rostov-on-Don, 344006 (Russian Federation)

    2011-08-24

    A Nd-doped BiFeO{sub 3} thin film deposited on MgO substrate was studied by synchrotron diffraction. The ferroelectric nature of the film is proven by in-plane remanent polarization measurement. The highest possible symmetry of the film is determined to be orthorhombic, within the Fm2m space group. Such a structure is rotated by 45{sup 0} with respect to the substrate and is consistent with tilts of oxygen octahedra doubling the unit cell. This polar structure presents a rather unusual strain-accommodation mechanism. (fast track communication)

  11. Orthorhombic polar Nd-doped BiFeO3 thin film on MgO substrate

    International Nuclear Information System (INIS)

    Leontyev, I N; Janolin, P-E; Dkhil, B; Yuzyuk, Yu I; El-Marssi, M; Chernyshov, D; Dmitriev, V; Golovko, Yu I; Mukhortov, V M

    2011-01-01

    A Nd-doped BiFeO 3 thin film deposited on MgO substrate was studied by synchrotron diffraction. The ferroelectric nature of the film is proven by in-plane remanent polarization measurement. The highest possible symmetry of the film is determined to be orthorhombic, within the Fm2m space group. Such a structure is rotated by 45 0 with respect to the substrate and is consistent with tilts of oxygen octahedra doubling the unit cell. This polar structure presents a rather unusual strain-accommodation mechanism. (fast track communication)

  12. The Improvement of Dehydriding the Kinetics of NaMgH3 Hydride via Doping with Carbon Nanomaterials

    Directory of Open Access Journals (Sweden)

    Zhong-Min Wang

    2016-12-01

    Full Text Available NaMgH3 perovskite hydride and NaMgH3–carbon nanomaterials (NH-CM composites were prepared via the reactive ball-milling method. To investigate the catalytic effect of CM on the dehydriding kinetic properties of NaMgH3 hydride, multiwall carbon nanotubes (MWCNTs and graphene oxide (GO were used as catalytic additives. It was found that dehydriding temperatures and activation energies (ΔE1 and ΔE2 for two dehydrogenation steps of NaMgH3 hydride can be greatly reduced with a 5 wt. % CM addition. The NH–2.5M–2.5G composite presents better dehydriding kinetics, a lower dehydriding temperature, and a higher hydrogen-desorbed amount (3.64 wt. %, 638 K. ΔE1 and ΔE2 can be reduced by about 67 kJ/mol and 30 kJ/mol, respectively. The results suggest that the combination of MWCNTs and GO is a better catalyst as compared to MWCNTs or GO alone.

  13. 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.

  14. 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

  15. 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)

  16. Experimental studies on mechanical properties of T6 treated Al25Mg2Si2Cu4Fe alloy

    Science.gov (United States)

    Sondur, D. G.; Mallapur, D. G.; Udupa, K. Rajendra

    2018-04-01

    Effect of T6 treatment on the mechanical properties of Al25Mg2Si2Cu4Fe alloy was evaluated by conducting mechanical tests on test pieces using universal testing machine. Increase in the mechanical properties such as ultimate tensile strength, hardness and % elongation was observed. Microstructure characterization revealed the modification in the size and shapes of the precipitates formed during the homogenization process. This modification increases the anisotropy of the microstructure and the stresses in the as cast structure. The increase in the hardness of T6 treated alloy is due to the partial recrystallization, fragmentation and redistribution of primary Mg2Si phase, precipitation of fine θ, Q phases. The high volume fractions of uniformly dispersed hard β-particles greatly increase the flow stress and provide an appreciable impediment to plastic deformation. Thus increasing the hardness of the alloy.

  17. Estudo etnobotânico de plantas medicinais na comunidade de Santa Rita, Ituiutaba – MG

    Directory of Open Access Journals (Sweden)

    Juliana Aparecida Povh

    2013-07-01

    Full Text Available http://dx.doi.org/10.5007/2175-7925.2013v26n3p231 O objetivo deste artigo foi inventariar as plantas utilizadas na medicina popular pelos membros da comunidade rural de Santa Rita, no município de Ituiutaba - MG. A avaliação foi realizada por meio de entrevistas, com um questionário semiestruturado, e posterior coleta das plantas indicadas pelos informantes. Foram realizadas 47 entrevistas e 127 espécies foram listadas, pertencentes a 55 famílias de Angiospermas. Para obtenção dos dados quantitativos foi calculada a porcentagem de Concordância de Usos Principais (CUP de cada espécie; para identificar as indicações terapêuticas de maior importância, utilizou-se o Fator de Consenso dos Informantes (FCI. A CUP demonstrou que 5,5% das plantas citadas são amplamente utilizadas pela comunidade. As famílias botânicas predominantes foram Lamiaceae e Asteraceae, com 14 e 13 registros, respectivamente. A indicação de uso predominante envolveu, principalmente, afecções relacionadas a distúrbio emocional, conforme indicado pelo FCI. Salienta-se que 60,7% das plantas citadas neste artigo são espécies exóticas; desse modo, se faz necessário mais estudos para catalogar o conhecimento sobre as plantas medicinais nativas dessa região.

  18. 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.

  19. 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.

  20. First Simultaneous and Common-Volume Lidar Observations of Na and Fe Metals, Temperatures, and Vertical Winds in Antarctica

    Science.gov (United States)

    Chu, X.

    2017-12-01

    A new STAR Na Doppler lidar will be installed to Arrival Heights near McMurdo Station, Antarctica in October 2017. This new lidar will be operated next to an existing Fe Boltzmann lidar to make simultaneous and common-volume measurements of metal Na and Fe layers, neutral temperatures, and vertical winds in the mesosphere and thermosphere, up to nearly 200 km. These measurements will be used to study a variety of science topics, e.g., the meteoric metal layers, wave dynamics, polar mesospheric clouds, constituent and heat fluxes, and cosmic dust. The discoveries of thermospheric neutral Fe layers and persistent gravity waves by the Fe Boltzmann lidar observations has opened a new door to explore the space-atmosphere interactions with ground-based instruments, especially in the least understood but crucially important altitude range of 100-200 km. These neutral metal layers provide excellent tracers for modern resonance lidars to measure the neutral wind and temperature directly. Even more exciting, the neutral metal layers in the thermosphere provide a natural laboratory to test our fundamental understandings of the atmosphere-ionosphere-magnetosphere coupling and processes. This paper will report the first summer results from the simultaneous Na and Fe lidar observations from Antarctica, and highlight important discoveries made by the Fe lidar during its first seven years of campaign at McMurdo. A thermosphere-ionosphere Fe/Fe+ (TIFe) model will be introduced to explain the TIFe layers in Antarctica.

  1. Room-temperature ferromagnetism in Fe-based perovskite solid solution in lead-free ferroelectric Bi0.5Na0.5TiO3 materials

    Science.gov (United States)

    Hung, Nguyen The; Bac, Luong Huu; Trung, Nguyen Ngoc; Hoang, Nguyen The; Van Vinh, Pham; Dung, Dang Duc

    2018-04-01

    The integration of ferromagnetism in lead-free ferroelectric materials is important to fabricate smart materials for electronic devices. In this work, (1 - x)Bi0.5Na0.5TiO3 + xMgFeO3-δ materials (x = 0-9 mol%) were prepared through sol-gel method. X-ray diffraction characterization indicated that MgFeO3-δ materials existed as a well solid solution in lead-free ferroelectric Bi0.5Na0.5TiO3 materials. The rhombohedral structure of Bi0.5Na0.5TiO3 materials was distorted due to the random distribution of Mg and Fe cations into the host lattice. The reduced optical band gap and the induced room-temperature ferromagnetism were due to the spin splitting of transition metal substitution at the B-site of perovskite Bi0.5Na0.5TiO3 and the modification by A-site co-substitution. This work elucidates the role of secondary phase as solid solution in Bi0.5Na0.5TiO3 material for development of lead-free multiferroelectric materials.

  2. 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.

  3. Phase formation in Na2MoO4 - MgMoO4 - Cr2(MoO4)3 system

    International Nuclear Information System (INIS)

    Kotova, I.Yu.; Kozhevnikova, N.M.

    1998-01-01

    Interaction within Na 2 MoO 4 - MgMoO 4 - Cr 2 (MoO 4 ) 3 ternary system is studied by X ray phase and DTA methods. State diagram of NaCr(MoO 4 ) 2 - MgMoO 4 section is plotted. Production of ternary molybdates of Na 1-x Mg 1-x Cr 1+x (MoO 4 ) 3 , where 0 ≤ x ≤ 0.3, and NaMg 3 Cr(MoO 4 ) 5 composition is ascertained [ru

  4. 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....

  5. Interplay of uniaxial and cubic anisotropy in epitaxial Fe thin films on MgO (001 substrate

    Directory of Open Access Journals (Sweden)

    Srijani Mallik

    2014-09-01

    Full Text Available Epitaxial Fe thin films were grown on annealed MgO(001 substrates at oblique incidence by DC magnetron sputtering. Due to the oblique growth configuration, uniaxial anisotropy was found to be superimposed on the expected four-fold cubic anisotropy. A detailed study of in-plane magnetic hysteresis for Fe on MgO thin films has been performed by Magneto Optic Kerr Effect (MOKE magnetometer. Both single step and double step loops have been observed depending on the angle between the applied field and easy axis i.e. along ⟨100⟩ direction. Domain images during magnetization reversal were captured by Kerr microscope. Domain images clearly evidence two successive and separate 90° domain wall (DW nucleation and motion along cubic easy cum uniaxial easy axis and cubic easy cum uniaxial hard axis, respectively. However, along cubic hard axis two 180° domain wall motion dominate the magnetization reversal process. In spite of having four-fold anisotropy it is essential to explain magnetization reversal mechanism in 0°< ϕ < 90° span as uniaxial anisotropy plays a major role in this system. Also it is shown that substrate rotation can suppress the effect of uniaxial anisotropy superimposed on four-fold anisotropy.

  6. 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.

  7. 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.

  8. Separation of reaction mechanisms at low energy. Study of the reactions: 27Al(d,p) 28Al, 24Mg(d,p) 25Mg, and 24Mg(d, α) 22Na

    International Nuclear Information System (INIS)

    Mermaz, M.

    1966-06-01

    The two sets of angular distributions of (d,p) reactions on Al and Mg, measured between 2 and 6 MeV, have given the possibility to test, in analysing the statistical fluctuations of cross-section, the validity of the separation of their mean values in two parts, one 'direct', another given by the statistical mechanism. With the same method of analysis we have studied excitation functions for several alpha groups of the reaction 24 Mg(d, α) 22 Na and given an evidence for an intermediate structure for the alpha channel leading to the 3. excited state of 22 Na. The angular distribution of the wide resonance at 15.9 MeV in 26 Al has been obtained. (author) [fr

  9. Thermodynamic of hydration of a Wyoming montmorillonite saturated with Ca, Mg, Na and K

    International Nuclear Information System (INIS)

    Vieillard, P.; Blanc, P.; Gailhanou, H.; Gaboreau, S.; Giffaut, E.

    2010-01-01

    enthalpy of immersion, and isotherms of adsorption - desorption has been done for Wyoming montmorillonite saturated by Mg 2+ , Ca 2+ , Na + and K + . Smectite water-vapor pressure isotherms represent the total concentration of H 2 O taken up the sample which is distributed among the interlayers, the outer surfaces of particles and the open pore space in the sample. In order to retrieve standard state thermodynamic properties for smectite hydration and dehydration from such data, the amount of H 2 O in excess of that in the interlayer must be assessed and subtracted from the total amount taken up by the clay sample. Berend et al. (1995), Cases et al. (1992, 1997) provide careful measurements of recovering waters in both processes (hydration and dehydration) on Wyoming saturated by monovalent and divalent cations. Despite the fact that neither the hydration, nor the dehydration isotherm necessarily represents the equilibrium state of the system, the two isotherms together can be considered to bracket the equilibrium values of Xhs and the activity of H 2 O. Paired hydration and dehydration isotherm in the one hand and enthalpy of immersion in the other hand, which constitute the limits of these brackets can be regressed to assess standard state thermodynamic parameters (enthalpy and entropy) for the hydration- dehydration process. Experimental enthalpies of hydration are used in the determination of ΔH deg. hyd. W H1 and W H2 by the minimization technique. For the adsorption-desorption isotherms, the determination of parameters ΔS deg. hyd. W S1 and W S2 are obtained by minimizing the difference between measured sets of data (relative humidity and number of adsorbed interlayer water) and calculated ones. For each Wyoming saturated with one cation, six parameters are requested and characterize the standard state thermodynamic properties of hydration between smectite and interlayer H 2 O. Relations between hydration parameters ΔH deg. hyd. and ΔS deg. hyd. in the one hand

  10. Synthesis, crystal structure and electrochemical properties of the manganese-doped LiNaFe[PO{sub 4}]F materials

    Energy Technology Data Exchange (ETDEWEB)

    Ben Yahia, Hamdi, E-mail: benyahia.hamdi@aist.go.jp; Shikano, Masahiro, E-mail: shikano.masahiro@aist.go.jp; Sakaebe, Hikari; Kobayashi, Hironori

    2013-08-15

    The new compounds LiNaFe{sub 1−x}Mn{sub x}[PO{sub 4}]F (x ≤ 1/4) were synthesized by a solid state reaction route. The crystal structure of LiNaFe{sub 3/4}Mn{sub 1/4}[PO{sub 4}]F was determined from single crystal X-ray diffraction data. LiNaFe{sub 3/4}Mn{sub 1/4}[PO{sub 4}]F crystallizes with the Li{sub 2}Ni[PO{sub 4}]F-type structure, space group Pnma, a = 10.9719(13), b = 6.3528(7), c = 11.4532(13) Å, V = 798.31(16) Å{sup 3}, and Z = 8. The structure consists of edge-sharing (Fe{sub 3/4}Mn{sub 1/4})O{sub 4}F{sub 2} octahedra forming (Fe{sub 3/4}Mn{sub 1/4})FO{sub 3} chains running along the b-axis. These chains are interlinked by PO{sub 4} tetrahedra forming a three-dimensional framework with the tunnels and the cavities filled by the well-ordered sodium and lithium atoms, respectively. The manganese-doped phases show poor electrochemical behavior comparing to the iron pure phase LiNaFe[PO{sub 4}]F. - Highlights: • We investigated the synthesis of LiNaFe{sub 1−x}Mn{sub x}[PO{sub 4}]F by solid state reaction. • We demonstrated that a solid solution exist only for x ≤ 1/4. • We solved the crystal structure of LiNaFe{sub 3/4}Mn{sub 1/4}[PO{sub 4}]F using single crystal data. • We studied the electrochemical performances of LiNaFe{sub 1−x}Mn{sub x}[PO{sub 4}]F. • The Mn-doped phases have poor electrochemical performances comparing to LiNaFe[PO{sub 4}]F.

  11. 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.

  12. Noise spectroscopy of CoFeB/MgO/CoFeB magnetic tunnel junctions in the presence of thermal gradients

    Energy Technology Data Exchange (ETDEWEB)

    Liebing, N. [Physikalisch-Technische Bundesanstalt, Bundesallee 100, d-38116 Braunschweig (Germany); Serrano-Guisan, S., E-mail: santiago.serrano-guisan@inl.int [International Iberian Nanotechnology Laboratory, Avenida Mestre Jose Veiga, 4715-330 Braga (Portugal); Rott, K.; Reiss, G. [University of Bielefeld, Department of Physics, Univesitätesstr. 25, d-33615 Bielefeld (Germany); Schumacher, H.W., E-mail: hans.w.schumacher@ptb.de [Physikalisch-Technische Bundesanstalt, Bundesallee 100, d-38116 Braunschweig (Germany)

    2016-02-15

    We present experimental data of the precessional dynamics of the free layer of CoFeB/MgO/CoFeB based magnetic tunnel junctions (MTJ) in the presence of thermal gradients across the MTJ. The free layer precession is investigated by noise spectroscopy. Thermal gradients of the order of tens of mK/nm across the MTJ are generated by electrical heating. Without applied thermal gradients we find spin transfer torque modified magnetization precession. With increasing thermal gradients we generally observe a decrease of the precession frequency which could be related to an increasing overall free layer temperature. However an asymmetry of the line width behavior for parallel and antiparallel orientation points towards additional effects beyond thermal activation. This could be a hint for the modification of the precessional dynamics in magnetic tunnel junctions by thermal spin torques. - Highlights: • Thermal gradients induced magnetization dynamics on MTJ structures are explored. • Magnetic noise spectroscopy is carried out to study the efficiency of such effects. • A decrease of resonance frequency is observed at both MTJ states for large ∇T. • An asymmetric linewidth behavior is observed for both MTJ states under ∇T. • Additional thermal effects beyond thermal activation must be considered.

  13. 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.

  14. 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).

  15. 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.

  16. The effect of disorder on electronic and magnetic properties of quaternary Heusler alloy CoFeMnSi with LiMgPbSb-type structure

    International Nuclear Information System (INIS)

    Feng, Yu; Chen, Hong; Yuan, Hongkuan; Zhou, Ying; Chen, Xiaorui

    2015-01-01

    Thin films based on Heusler alloy often lost their theoretical predicted ultra-high spin polarization owing to the appearance of disorder. Using the first-principles calculations within density functional theory (DFT), we investigate the effect of disorder including antisite and swap on electronic and magnetic properties of quaternary Heusler alloy CoFeMnSi with LiMgPbSb-type structure. Twelve kinds of antisites and six kinds of swap disorders are proposed and studied comprehensively. In our calculations, Co(Fe)-, Mn(Fe)-, Si(Mn)-antisite and Co–Fe swap disorders are most favorable due to their lowest formation energies. Moreover, the positive binding energies of Co–Fe, Co–Si, Fe–Si and Mn–Si swap disorders with respect to their corresponding antisite disorders indicate that these complex swap disorders are more stable compared with their corresponding isolated antisite disorders. The investigations on density of states (DOS) show that the spin down energy gap of disordered structures suffers contraction and their DOS entirely move towards lower zone. Besides, the 100% spin polarization is maintained in all structures with antisite and swap disorders except for those with Co(Mn)-, Co(Si)-antisite and Co–Mn, Co–Si swap disorders. Therefore, the half-metallicity of quaternary Heusler alloy CoFeMnSi is quite robust against interfering effects such as Si(Mn), Co(Fe) and Co–Fe disorders most possibly formed in the growth. - Highlights: • CoFeMnSi with LiMgPbSb-type structure is found to be a half-metallic ferromagnet. • Si(Mn), Co(Fe), Mn(Fe) antisites and Co–Fe swap disorders are most likely to form. • The half-metallicity of CoFeMnSi is robust against the most possible disorders. • The magnetic moments of the most possible disorders follow the Pauli-Slater rule

  17. Effects of Cu or Ag additions on the kinetics of MgB2 phase formation in Fe-sheated wires

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Abrahamsen, Asger Bech; Bednarcik, J.

    2008-01-01

    MgB2/Fe wires have been produced by the powder-in-tube technique following the in situ route. The influence of low amounts of Cu or Ag additions into the precursor powder mixture on the kinetics of MgB2 formation was studied in situ by means of synchrotron x-ray diffraction during heat-treatments...

  18. 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.

  19. Photoluminescence of the Mg2Al4Si5O18-Al2O3-MgAl2O4-SiO2 ceramic system containing Fe3+ and Cr3+ as impurity ions

    Science.gov (United States)

    Sosman, L. P.; López, A.; Pedro, S. S.; Papa, A. R. R.

    2018-02-01

    This work presents the results of photoluminescence, excitation and radiative decay time for a ceramic system containing Mg2Al4Si5O18-Al2O3-MgAl2O4-SiO2 with Fe3+ and Cr3+ as impurity ions. Emission data were obtained using several excitation wavelengths and the excitation data were acquired for the most intense emission bands. The optical results were analyzed according to the Tanabe-Sugano (TS) theory from which the crystalline field parameter Dq and Racah parameters B and C were obtained for the Fe3+ and Cr3+ sites. The results indicate that the Fe3+ and Cr3+ ions occupy tetrahedral and octahedral sites, respectively. The emission from Fe3+ and Cr3+ ions causes an intense and broad band ranging between 350 nm and 850 nm, showing that this material is a potential tunable radiation source at room temperature.

  20. Co2FeAl Heusler thin films grown on Si and MgO substrates: Annealing temperature effect

    International Nuclear Information System (INIS)

    Belmeguenai, M.; Tuzcuoglu, H.; Zighem, F.; Chérif, S. M.; Moch, P.; Gabor, M. S.; Petrisor, T.; Tiusan, C.

    2014-01-01

    10 nm and 50 nm Co 2 FeAl (CFA) thin films have been deposited on MgO(001) and Si(001) substrates by magnetron sputtering and annealed at different temperatures. X-rays diffraction revealed polycrystalline or epitaxial growth (according to CFA(001)[110]//MgO(001)[100] epitaxial relation) for CFA films grown on a Si and on a MgO substrate, respectively. For these later, the chemical order varies from the A2 phase to the B2 phase when increasing the annealing temperature (T a ), while only the A2 disorder type has been observed for CFA grown on Si. Microstrip ferromagnetic resonance (MS-FMR) measurements revealed that the in-plane anisotropy results from the superposition of a uniaxial and a fourfold symmetry term for CFA grown on MgO substrates. This fourfold anisotropy, which disappears completely for samples grown on Si, is in accord with the crystal structure of the samples. The fourfold anisotropy field decreases when increasing T a , while the uniaxial anisotropy field is nearly unaffected by T a within the investigated range. The MS-FMR data also allow for concluding that the gyromagnetic factor remains constant and that the exchange stiffness constant increases with T a . Finally, the FMR linewidth decreases when increasing T a , due to the enhancement of the chemical order. We derive a very low intrinsic damping parameter (1.1×10 −3 and 1.3×10 −3 for films of 50 nm thickness annealed at 615 °C grown on MgO and on Si, respectively)

  1. 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.

  2. 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.

  3. Separation of reaction mechanisms at low energy. Study of the reactions: {sup 27}Al(d,p) {sup 28}Al, {sup 24}Mg(d,p) {sup 25}Mg, and {sup 24}Mg(d, {alpha}) {sup 22}Na; Sur la separation des mecanismes de reaction a basse energie. Etude des reactions: {sup 27}Al(d,p) {sup 28}Al, {sup 24}Mg(d,p) {sup 25}Mg, et {sup 24}Mg(d, {alpha}) {sup 22}Na

    Energy Technology Data Exchange (ETDEWEB)

    Mermaz, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-06-01

    The two sets of angular distributions of (d,p) reactions on Al and Mg, measured between 2 and 6 MeV, have given the possibility to test, in analysing the statistical fluctuations of cross-section, the validity of the separation of their mean values in two parts, one 'direct', another given by the statistical mechanism. With the same method of analysis we have studied excitation functions for several alpha groups of the reaction {sup 24}Mg(d, {alpha}) {sup 22}Na and given an evidence for an intermediate structure for the alpha channel leading to the 3. excited state of {sup 22}Na. The angular distribution of the wide resonance at 15.9 MeV in {sup 26}Al has been obtained. (author) [French] Les deux ensembles de distributions angulaires des reactions (d,p) sur Al et Mg, mesures entre 2 et 6 MeV, nous ont permis, en analysant les fluctuations statistiques de sections efficaces, de verifier la possibilite de la separation de leurs valeurs moyennes en deux composantes: l'une 'directe', l'autre due au mecanisme statistique. Avec la meme methode d'analyse nous avons etudie les fonctions d'excitation des premiers groupes alpha de la reaction {sup 24}Mg(d,{alpha}) {sup 22}Na et mis en evidence une structure intermediaire pour la voie de reaction aboutissant au 3eme niveau de {sup 22}Na. Nous avons obtenu la distribution angulaire de la resonance large situee a une energie d'excitation de 15,9 MeV dans {sup 26}Al. (auteur)

  4. Separation of reaction mechanisms at low energy. Study of the reactions: {sup 27}Al(d,p) {sup 28}Al, {sup 24}Mg(d,p) {sup 25}Mg, and {sup 24}Mg(d, {alpha}) {sup 22}Na; Sur la separation des mecanismes de reaction a basse energie. Etude des reactions: {sup 27}Al(d,p) {sup 28}Al, {sup 24}Mg(d,p) {sup 25}Mg, et {sup 24}Mg(d, {alpha}) {sup 22}Na

    Energy Technology Data Exchange (ETDEWEB)

    Mermaz, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-06-01

    The two sets of angular distributions of (d,p) reactions on Al and Mg, measured between 2 and 6 MeV, have given the possibility to test, in analysing the statistical fluctuations of cross-section, the validity of the separation of their mean values in two parts, one 'direct', another given by the statistical mechanism. With the same method of analysis we have studied excitation functions for several alpha groups of the reaction {sup 24}Mg(d, {alpha}) {sup 22}Na and given an evidence for an intermediate structure for the alpha channel leading to the 3. excited state of {sup 22}Na. The angular distribution of the wide resonance at 15.9 MeV in {sup 26}Al has been obtained. (author) [French] Les deux ensembles de distributions angulaires des reactions (d,p) sur Al et Mg, mesures entre 2 et 6 MeV, nous ont permis, en analysant les fluctuations statistiques de sections efficaces, de verifier la possibilite de la separation de leurs valeurs moyennes en deux composantes: l'une 'directe', l'autre due au mecanisme statistique. Avec la meme methode d'analyse nous avons etudie les fonctions d'excitation des premiers groupes alpha de la reaction {sup 24}Mg(d,{alpha}) {sup 22}Na et mis en evidence une structure intermediaire pour la voie de reaction aboutissant au 3eme niveau de {sup 22}Na. Nous avons obtenu la distribution angulaire de la resonance large situee a une energie d'excitation de 15,9 MeV dans {sup 26}Al. (auteur)

  5. Los elementos traza (Mg, Sr, Ha, Fe, Mn) en carbonatos: ambiente genético del Karst del techo de la unidad intermedia de la Cuenca neógena de Madrid.

    OpenAIRE

    Cañaveras Jiménez, Juan Carlos; Ordóñez Delgado, Salvador; Hoyos Gómez, Manuel; Calvo Sorando, José Pedro

    1992-01-01

    Este trabajo trata de caracterizar geoquímicamente el karst del techo de la U. Intermedia del Mioceno en las partes centrales de la Cuenca de Madrid. Para ello se han estudiado una serie de elementos traza (Mg, Sr, Na, Fe y Mn) mediante fluorescencia de rayos X. En base a este estudio se han distinguido dos tipos de procesos: De reemplazamiento y/o recristalización, que implican la litificación y homogeneización química de un sedimento calcítico-dolomítico; y procesos de precipitación química...

  6. 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.

  7. 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.

  8. Sensitivity of the mayfly Adenophlebia auriculata (Ephemeroptera: Leptophlebiidae) to MgSO4 and Na2SO4

    Science.gov (United States)

    Vellemu, E. C.; Mensah, P. K.; Griffin, N. J.; Odume, O. N.

    2017-08-01

    Acid mine drainage (AMD) continues to deteriorate water quality in freshwater ecosystems. Sulphates, a major salt component in AMD, can exacerbate AMD effects in freshwater because salts are toxic to aquatic life in high concentrations. Sulphates are predominant in South African AMD impacted freshwater ecosystems. In this study, the sensitivity of nymphs of the mayfly Adenophlebia auriculata (Ephemeroptera: Leptophlebiidae) was investigated by exposing the organisms to magnesium sulphate (MgSO4) and sodium sulphate (Na2SO4) as models of mining salinisation in short-term (96 h) and long-term (240 h) in static system tests. Short-term and long-term lethal concentrations of each salt were estimated using regression analyses. The results indicated that A. auriculata was more sensitive to MgSO4 (LC50 = 3.81 g/L) than Na2SO4 (LC50 = 8.78 g/L) after short-term exposures. However, this species became sensitive to Na2SO4 (LC10 = 0.19 g/L) but tolerant to MgSO4 (LC10 = 0.35 g/L) after long-term exposures. These results suggest that the 0.25 g/L sulphate compliance limit for South Africa is inadequate to protect A. auriculata from Na2SO4 toxicity in the long-term, yet it overprotects this species from MgSO4 exposures in the short-term. The findings of this study are an important major step in understanding the ecological effects of AMD to aquatic life.

  9. 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.

  10. Raman microspectroscopic study of effects of Na(I) and Mg(II) ions on low pH induced DNA structural changes

    NARCIS (Netherlands)

    Muntean, C.M.; Segers-Nolten, Gezina M.J.

    2003-01-01

    In this work a confocal Raman microspectrometer is used to investigate the influence of Na+ and Mg2+ ions on the DNA structural changes induced by low pH. Measurements are carried out on calf thymus DNA at neutral pH (7) and pH 3 in the presence of low and high concentrations of Na+ and Mg2+ ions,

  11. The influence of ball-milling time on the dehydrogenation properties of the NaAlH4-MgH2 composite

    NARCIS (Netherlands)

    Bendyna, J.K.; Dyjak, S.M.; Notten, P.H.L.

    2015-01-01

    The recently developed NaAlH4eMgH2 composite shows improved hydrogen-storage properties compared to MgH2 and NaAlH4. However, the dehydrogenation reaction rates are still too limited, hampering practical applications. Mechanical ball milling is broadly used to improve the dehydrogenation reaction

  12. Electrical and magnetic properties of MgGa_(_2_-_x_)Fe_xO_4 ferrite

    International Nuclear Information System (INIS)

    Ribeiro, Vander Alkmin dos Santos

    2005-01-01

    The ceramics of the type ferrites are materials that present important characteristics of electrical conduction and magnetic properties, as much as material magnetic hard, how much of soft magnetic materials. The cubic ferrites of the spinel structure are oxides with chemical formula MFe_2O_4, where M is a divalent metallic ion. Due to characteristic of the spinel, diverse magnetic configurations are a gotten, depending on the occupation tax of the magnetic ion (in general iron) in each sublattice. The diluted ferrites possess general formula given for: MD_2_-_xFe_xO4, where M and D are diamagnetic ions, being D the ion of substitution doping and x is the concentration of ions of iron (0,002 ≤ x ≤ 0,350). The sample was prepared using ceramics techniques in reaction of solid state and later they were submitted to a magnetic characterization, electric and X-ray diffraction. The results of the magnetic characterization were gotten by a magnetometer of vibrant sample (VSM) EG&G-Princeton Applied Research, model 4500; the characterization for X-ray was used one X-ray diffractometer, model URD 65; of the Seifert & with. Electrical measurements DC were carried through with the use of a unit high-voltage measuring source - Keithley, model 237, where the voltage applied in the samples varied of 0-40 V, the high temperatures. Two types of contacts were used: the arrangement type 'sandwich', being the inferior electrode the proper door-sample, and the superior electrode with ring geometry and a silver was pasted on both sides of the samples to ensure good electrical contact. The magnetic measurements confirm its ferrite characteristics and in the electrical measurements, the electrical conductivity indicated behavior of a semiconductor the high temperatures and the process of electrical conduction thermally presented to be activated. (author)

  13. THE COMPARATIVE ANALYSIS OF THE ACTIVITY ASSAY METHODS FOR MG2+-DEPENDENT NA+/K+-ACTIVATED ATPASE IN ERYTHROCYTE MEMBRANES

    Directory of Open Access Journals (Sweden)

    Polina Anatolevna Petrova

    2017-12-01

    Full Text Available This review considers the methodological reasons for the wide range of results for the red blood cells Mg2+-dependent Na+/K+-ATPase activity described by different authors. We assert that the differences in the Na+/K+-ATPase activity obtained by the researchers are due to the methodological peculiarities associated with methods of obtaining and measurement of the enzyme activity, such as red blood cells separation and storage (centrifugation, concentration and composition of the lysing solution, time and temperature of hemolysis and freezing, as well as the peculiarities of methods for the quantitative determination of protein and inorganic phosphorus. On the basis of the literature data analysis we recommend that for the most accurate determination of the Na+/K+-ATPase activity it is better to use the chelator in the lysing buffer solution and Fiske-Subbarow and Lowry methods for the determination of inorganic phosphorus and quantitative protein content, respectively.

  14. Borophene as an anode material for Ca, Mg, Na or Li ion storage: A first-principle study

    Science.gov (United States)

    Mortazavi, Bohayra; Dianat, Arezoo; Rahaman, Obaidur; Cuniberti, Gianaurelio; Rabczuk, Timon

    2016-10-01

    Borophene, the boron atom analogue to graphene, being atomic thick have been just recently experimentally fabricated. In this work, we employ first-principles density functional theory calculations to investigate the interaction of Ca, Mg, Na or Li atoms with single-layer and free-standing borophene. We first identified the most stable binding sites and their corresponding binding energies as well and then we gradually increased the ions concentration. Our calculations predict strong binding energies of around 4.03 eV, 2.09 eV, 2.92 eV and 3.28 eV between the borophene substrate and Ca, Mg, Na or Li ions, respectively. We found that the binding energy generally decreases by increasing the ions content. Using the Bader charge analysis, we evaluate the charge transfer between the adatoms and the borophene sheet. Our investigation proposes the borophene as a 2D material with a remarkably high capacity of around 800 mA h/g, 1960 mA h/g, 1380 mA h/g and 1720 mA h/g for Ca, Mg, Na or Li ions storage, respectively. This study can be useful for the possible application of borophene for the rechargeable ion batteries.

  15. Synthesis and thermoluminescence characterization of Na6Mg(SO4)4:RE (RE = Ce, Tb) phosphors

    International Nuclear Information System (INIS)

    Kore, Bhushan P.; Dhoble, N.S.; Dhoble, S.J.

    2014-01-01

    Thermoluminescence (TL) properties of sulfate-based phosphors activated by different rare earths have received tremendous attention to the field of radiation dosimetry. Those TL materials based on CaSO 4 have been widely applied for medical and environmental dosimetry. Taking this fact into account we have synthesized Na 6 Mg(SO 4 ) 4 doped with Ce and Tb by wet chemical method. The prepared phosphor was characterized by XRD, FTIR, photoluminescence (PL) and thermoluminescence. For TL study, the phosphor is irradiated with γ-rays from 60 Co source. For studying luminescence properties, the prepared phosphor was annealed at different temperatures and effects of these annealing temperatures on Na 6 Mg(SO 4 ) 4 samples are investigated and quantified. The changes in the glow curve and PL emission spectrum are also investigated as a function of annealing temperature and the annealing temperature was optimized. For calculation of trapping parameters various methods such as peak shape (PS) method, initial rise (IR) method, various heating rate (VHR) method, and computerized glow curve deconvolution (CGCD) are employed. - Highlights: • Na 6 Mg(SO 4 ) 4 phosphor was successfully prepared by wet chemical method. • Effect of annealing temperatures on PL and TL properties has been studied. • Different trap analysis methods were used for calculating the trapping parameters. • Effect of these methods on activation energies were investigated in detail

  16. Mapeamento preliminar de solos com horizonte B textural e B nítico na região de Lavras, MG Preliminary mapping of alfisols and ultisols in the region of Lavras, MG

    Directory of Open Access Journals (Sweden)

    Marilusa Pinto Coelho Lacerda

    2009-06-01

    Full Text Available Estudos de caracterização de solos e estabelecimento de relações entre pedologia, geologia e geomorfologia permitem a elaboração de modelos preditivos da distribuição dos solos na paisagem. Objetivou-se, com o presente trabalho, estudar estas relações, com a finalidade de representar a distribuição de solos com horizonte B textural e B nítico na paisagem da região de Lavras, MG, por intermédio da geração de mapa preliminar de solos, utilizando técnicas de geoprocessamento. Os estudos foram realizados em solos com horizonte B textural e B nítico, uma vez que esses solos apresentam características relacionadas à variação da composição geoquímica das rochas ígneas de origem, refletindo-se em vários atributos dos solos, enfatizando a cor e o teor de Fe2O3. Foram realizadas campanhas de campo com avaliações morfológicas, físicas e químicas de perfis de solos representativos, desenvolvidos a partir de unidades geológicas de composições geoquímicas distintas, estabelecendo as relações pedogeológicas. Verificou-se, também, a distribuição dos solos na paisagem, com o estabelecimento das relações pedogeomorfológicas. Foi constatado que tais solos são desenvolvidos na região em relevo caracterizado por classes de declividade de 12 a 45%, originando diferentes classes de solos com horizonte B textural e B nítico, diretamente relacionados à variação do material de origem. Os critérios estabelecidos nas relações entre pedologia, geologia e geomorfologia permitiram avaliar a distribuição dos solos na paisagem estudada e a geração do mapa preliminar de solos, com individualização de solos com horizonte B textural e B nítico.Studies of characterization of soils and establishment of relationships among pedology, geology and geomorphology allow the elaboration of models of soil distribution in landscaping. This study aimed at studies of this nature, with the purpose of representing the distribution of

  17. Magnetic characteristics of M2FeV3O11 (M = Mg, Zn, Pb, Co, Ni) compounds

    Science.gov (United States)

    Groń, T.; Blonska-Tabero, A.; Filipek, E.; Stokłosa, Z.; Duda, H.; Sawicki, B.

    2018-02-01

    The unusual physical characteristics of the multicomponent oxide systems renewed the interest as the potential cathode materials in high-energy cells. Since the earlier magnetic characteristics were not entirely conclusive, we report the results of dc magnetic measurements including higher harmonics of ac magnetic susceptibility of the M2FeV3O11 (M = Mg, Zn, Pb, Co, Ni) compounds. Ferrimagnetic long-range and antiferromagnetic short-range interactions for all compounds under study at low temperatures as well as superparamagnetic-like behavior with the blocking temperature of 29 K and the freezing parameter of 0.013 were observed. These effects are discussed within the framework of superexchange and double exchange magnetic interactions as well as the mixed valence band of iron ions.

  18. Ta thickness-dependent perpendicular magnetic anisotropy features in Ta/CoFeB/MgO/W free layer stacks

    Energy Technology Data Exchange (ETDEWEB)

    Yang, SeungMo; Lee, JaBin; An, GwangGuk [Novel Functional Materials and Devices Lab, The Research Institute for Natural Science, Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, JaeHong [Division of Nano-Scale Semiconductor Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Chung, WooSeong [Nano Quantum Electronics Lab, Department of Electronics and Computer Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Hong, JinPyo, E-mail: jphong@hanyang.ac.kr [Novel Functional Materials and Devices Lab, The Research Institute for Natural Science, Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of); Division of Nano-Scale Semiconductor Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2015-07-31

    We describe Ta underlayer thickness influence on thermal stability of perpendicular magnetic anisotropy in Ta/CoFeB/MgO/W stacks. It is believed that thermal stability based on Ta underlay is associated with thermally-activated Ta atom diffusion during annealing. The difference in Ta thickness-dependent diffusion behaviors was confirmed with X-ray photoelectron spectroscopy analysis. Along with a feasible Ta thickness model, our observations suggest that an appropriate seed layer choice is needed for high temperature annealing stability, a critical issue in the memory industry. - Highlights: • We observed changes in the diffusion behavior with regard to Ta seed layer thickness. • It was observed that a thinner Ta seed layer induced more annealing-stable features. • However, ultra-thin (0.75 nm) Ta shows unstable characteristics about the annealing process. • It was possibly due to a rugged interface of the Ta layer by the island growth process.

  19. Gigantic terahertz magnetochromism via electromagnons in the hexaferrite magnet Ba2Mg2Fe12O22

    Science.gov (United States)

    Kida, N.; Kumakura, S.; Ishiwata, S.; Taguchi, Y.; Tokura, Y.

    2011-02-01

    Effects of temperature (6-225 K) and magnetic field (0-7 T) on the low-energy (1.2-5 meV) electrodynamics of the electromagnon, the magnetic resonance driven by the light electric field, have been investigated for a hexaferrite magnet Ba2Mg2Fe12O22 by using terahertz time-domain spectroscopy. We find the gigantic terahertz magnetochromism via electromagnons; the magnetochromic change, as defined by the difference of the absorption intensity with and without magnetic field, exceeds 500% even at 0.6 T. The results arise from the fact that the spectral intensity of the electromagnon critically depends on the magnetic structure. With changing the conical spin structures in terms of the conical angle θ from the proper screw (θ=0°) to the ferrimagnetic (θ=90°) through the conical spin-ordered phases (0°origin of this electromagnon is argued in terms of the exchange-striction mechanism.

  20. Magneto-transport and thermoelectric properties of epitaxial FeSb{sub 2} thin film on MgO substrate

    Energy Technology Data Exchange (ETDEWEB)

    Duong, Anh Tuan; Rhim, S. H., E-mail: sonny@ulsan.ac.kr; Shin, Yooleemi; Nguyen, Van Quang; Cho, Sunglae, E-mail: slcho@ulsan.ac.kr [Department of Physics and Energy Harvest-Storage Research Center, University of Ulsan, Ulsan 680-749 (Korea, Republic of)

    2015-01-19

    We report magneto-transport and thermoelectric properties of FeSb{sub 2} thin film epitaxially grown on the MgO substrate using molecular beam epitaxy. The film exhibits compressive strain of 1.74% owing to large lattice mismatch, whose physical consequences are nontrivial. Magnetic phase has been changed from diamagnetic in bulk, as evidenced by anomalous Hall effect (AHE) and negative magneto-resistance (MR). The FeSb{sub 2} film is semiconducting without any metallic transition unlike the bulk counterpart. In particular, hysteresis in MR with distinct feature of AHE is evident with coercive field of 500 and 110 Oe for T = 20 and 50 K, respectively. Furthermore, from the Seebeck coefficients and temperature dependence of the resistivity, it is evident that the film is semiconducting with small band gap: 3.76 meV for T < 40 K and 13.48 meV for T > 40 K, respectively, where maximum thermoelectric power factor of 12 μV/cm·K at T = 50 K.

  1. Dendrimeric tweezers for recognition of fluorogenic Co{sup 2+}, Mg{sup 2+} and chromogenic Fe{sup 2+}

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Chandana B.; Meshram, Jyotsna S., E-mail: drjsmeshram@gmail.com

    2016-03-15

    Dendrimers are the attractive candidature for the formation of metal complexes capable of performing varied application, owing to the presence of multiple terminal groups on the exterior of the molecule has received tremendous attention. Herein, we have synthesized novel dendritic macromolecule (N′E,N‴E,N″‴E,N‴‴′E)-3,3′,3″,3‴-(ethane-1,2-diylbis(azanetriyle)) tetrakis(N'-(2-hydroxybenzyllidene)propanehydrazide) chemosensor L and its metal complexes. In the present study the application in the optical sensing for chromogenic Fe{sup 2+} and fluorogenic Co{sup 2+} and Mg{sup 2+}cation is reported. The dendrimeric chemosensor L and its metal complexes are investigated with the help of FTIR spectroscopy, Nuclear magnetic resonance ({sup 1}H NMR and {sup 13}C NMR), FT Raman Microspectroscopy, fluorescence and UV–visible spectroscopy. Thermal properties are studied using thermal gravimetric analysis. - Highlights: • Dual effect – Chromogenic and fluorogenic. Chemosensor shows chromogenic effect towards Fe{sup 2+} as well as fluorogenic effect towards Co{sup 2+}and Mg{sup 2+} cation. • From Linear fitting calibration plot for computing LOD and LOQ, it was detected that – LOD=32.3 nM, LOQ=97.8 nM. • Jobs Plot – A graph plotted [HG]={(ΔF/Fo)[H]} Vs {[H]v/([H]v+[G]v)} has maxima at 0.33 which corresponds to 1:2 stoichiometry of chemosensor L:Co{sup 2+}.

  2. MAPEAMENTO DE UNIDADES DE RELEVO NA MÉDIA SERRA DO ESPINHAÇO MERIDIONAL - MG

    Directory of Open Access Journals (Sweden)

    Éric Andrade Rezende

    2011-04-01

    Full Text Available O presente trabalho propõe um mapeamento de unidades de relevo para a porção sul do terço médio da Serra do Espinhaço Meridional. As unidades de relevo foram delimitadas a partir da análise integrada de cartas temáticas e imagens de satélite que permitiram observar variações na morfologia, na altimetria, na declividade, na litoestrutura e na organização da rede de drenagem. A etapa de cartografia digital, processada no software ArcGis 9.2, se baseou na utilização de produtos SRTM (Shuttle Radar Topography Mission. Os procedimentos metodológicos também incluíram trabalhos de campo e pesquisa bibliográfica. Foi empregada a taxonomia do mapeamento geomorfológico proposta pelo IBGE (2009, através da qual foram individualizadas quatorze Unidades Geomorfológicas. As unidades estão distribuídas entre cinco diferentes compartimentos do seguinte modo: dois planaltos, duas escarpas, seis depressões, três conjuntos de cristas e um conjunto de patamares. Foi possível observar que a disposição geral das unidades reflete o forte controle litoestrutural imposto ao relevo regional. Destaca-se a resistência diferenciada das diversas litologias frente aos processos denudacionais e a influência da neotectônica na geomorfogênese.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. Evaluation of chemically modified Ti–5Mo–3Fe alloy surface: Electrochemical aspects and in vitro bioactivity on MG63 cells

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, A. Madhan [Center of Research Excellence in Corrosion, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Sudhagar, P. [Energy Materials Laboratory, WCU Program Department of Energy Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Ramakrishna, Suresh [Graduate School of Biomedical Science and Engineering/College of Medicine, Hanyang University, Sungdong-gu, Seoul (Korea, Republic of); Kang, Yong Soo [Energy Materials Laboratory, WCU Program Department of Energy Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, Hyongbum [Graduate School of Biomedical Science and Engineering/College of Medicine, Hanyang University, Sungdong-gu, Seoul (Korea, Republic of); Gasem, Zuhair M. [Center of Research Excellence in Corrosion, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Rajendran, N., E-mail: nrajendran@annauniv.edu [Department of Chemistry, Anna University, Chennai (India)

    2014-07-01

    Ti–5Mo–3Fe (TMF) alloy is a newly developed β-titanium alloy with low modulus, and it has been deemed as suitable material for dental or orthopaedic implant. The aim of the present study is to evaluate the effect of alkali and hydrogen peroxide treatment on the corrosion and biological performance of TMF surface. The phases, morphology with chemical composition and topography of the treated surface were examined by X-ray diffraction, scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDAX) analysis and atomic force microscopy (AFM), respectively. Micro hardness of treated substrates was measured using Vicker's micro hardness method. The electrochemical studies were carried out using potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) measurements. In order to describe the bio-activity, contact angle measurements, in vitro characterisation and cell culture studies were performed for treated TMF surfaces in simulated body fluid (SBF) and MG63 cells. All these observations showed that the NaOH treatment is the most appropriate method for TMF alloy which exhibited superior biocompatibility and enhanced corrosion protection performance due to their hydrophilic, smooth, compact porous surface morphology than that of other substrates.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. AC impedance spectroscopy of NASICON type Na3Fe2(PO4)3 ceramic

    Science.gov (United States)

    Mandal, Biswajit; Thakur, A. K.

    2018-05-01

    Super ionic conductors (e.g.; A3M2(XO4)3, A=Li, Na) have received attention in applied research due to their interesting electrochemical property and inherently high ionic conductivity [1]. However, structural and compatibility requirements for fast ion transport is stringent and it plays a crucial role. In A3M2(XO4)3, a suitable cage formation in the crystal framework due to corner sharing arrangement of XO4 tetrahedra and MO6 octahedra creates voids that acts as host/guest site for cation transport. In this work, we report Nasicon structure Na3Fe2(PO4)3 (NFP) prepared via sol-gel route mediated by citric acid. Structural analysis confirmed that NFP sample belongs to monoclinic crystal structure having Cc space group (S. G. No 9) with lattice parameters, a=15.106 Å, b=8.722 Å, c=8.775 Å and β=124.96°. Electrical properties of the prepared sample have been studied by AC impedance spectroscopy technique. The AC conductivity results indicated typical signature of ionically conducting system.

  14. Y3Fe5O12/Na,Bi,Sr-doped PZT particulate magnetoelectric composites

    Science.gov (United States)

    Lisnevskaya, I. V.; Bobrova, I. A.; Lupeiko, T. G.; Agamirzoeva, M. R.; Myagkaya, K. V.

    2016-05-01

    Magnetoelectric (ME) composites of Na, Bi, Sr substituted lead zirconate titanate (PZT) and yttrium iron garnet having representative formula (100-x) wt% Na,Bi,Sr-doped PZT (PZTNB-1)+x wt% Y3Fe5O12 (YIG) with x=10-90 were manufactured using powdered components obtained through sol-gel processes. It is shown that the decrease in sintering temperature provided by the use of finely dispersed PZTNB-1 and YIG powders allows to significantly reduce content of fluorite-like foreign phase based on zirconium oxide, which forms due to the interfacial interaction during heat treatment and becomes stabilized by yttrium oxide. Connectivity has considerable effect on the value of ME coefficient of composite ceramics. With the same x value, ΔE/ΔH characteristic decreases when changing from 0-3-type structured composites (PZT grains embedded in ferrite matrix) to 3-3-(interpenetrating network of two phases) and especially 3-0-type samples (YIG grains embedded in PZT matrix); in the last case this can be attributed to the substrate clamping effect when ferrite grains are clamped with piezoelectric matrix. ΔE/ΔH value of 0-3 composites with x=40-60 wt% was found to be ∼1.6 mV/(cm Oe).

  15. The Ca, Cl, Mg, Na, and P mass fractions in benign and malignant giant cell tumors of bone investigated by neutron activation analysis

    International Nuclear Information System (INIS)

    Vladimir Zaichick; German Davydov; Tatyana Epatova; Sofia Zaichick

    2015-01-01

    The Ca, Cl, Mg, Na, and P content and Ca/P, Ca/Mg, Ca/Na, Cl/Ca, and Cl/Na ratios in samples of intact bone, benign and malignant giant cell tumor (GCT) of bone were investigated by neutron activation analysis with high resolution spectrometry of short-lived radionuclides. It was found that in GCT tissue the mass fractions of Cl and Na are higher and the mass fraction of Ca and P are lower than in normal bone tissues. Moreover, it was shown that higher Cl/Na mass fraction ratios as well as lower Ca/Cl, Ca/Mg, and Ca/Na mass fraction ratios are typical of the GCT tissue compared to intact bone. Finally, we propose to use the estimation of such parameters as the Cl mass fraction and the Ca/Cl mass fraction ratio as an additional test for differential diagnosis between benign and malignant GCT. (author)

  16. Fast solution combustion synthesis of porous NaFeTi3O8 with superior sodium storage properties

    Science.gov (United States)

    Zhao, Jin-Bao; Li, Xue; Xiao, Qian

    2018-01-01

    In this work, NaFeTi3O8 with three-dimensional porous net-like sheet morphology is firstly prepared by a simple and effective solution combustion method. Encouragingly, when being assessed as an anode electrode for sodium ion batteries, the NaFeTi3O8 net-like sheet composite exhibits superior electrochemical properties. We also study the effect of the combustion fuel glycine. The results indicate that the NaFeTi3O8 composite tends to be porous with glycine as the combustion fuel, which displays more excellent long cyclic stability (discharge capacity of 91 mA h g-1 after 1000 cycles at the current density of 0.5 A g-1) and superior rate performance (84.4 mA h g-1 even at 1.6 A g-1) than that of NaFeTi3O8 without glycine as the combustion agent. The enhanced electrochemical properties could be ascribed to the unique porous morphology, which achieves better electrolyte infiltration and faster ion diffusion. [Figure not available: see fulltext.

  17. Crystal structures and magnetic properties of iron (III)-based phosphates: Na{sub 4}NiFe(PO{sub 4}){sub 3} and Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Essehli, Rachid, E-mail: rachid_essehli@yahoo.fr [Laboratory of Mineral Solid and Analytical Chemistry ' LCSMA' , Department of Chemistry, Faculty of Sciences, University Mohamed I, Po. Box 717, 60000 Oujda (Morocco); Bali, Brahim El [Laboratory of Mineral Solid and Analytical Chemistry ' LCSMA' , Department of Chemistry, Faculty of Sciences, University Mohamed I, Po. Box 717, 60000 Oujda (Morocco); Benmokhtar, Said [LCMS, Laboratoire de Chimie des Materiaux Solides, Departement de chimie, Faculte des Sciences Ben M' SIK, Casablanca (Morocco); Bouziane, Khalid [Physics Department, College of Science, Sultan Qaboos University, PO Box 36, Postal Code 123 Al Khod, Sultanate of Oman (Oman); Manoun, Bouchaib [Laboratoire de Physico-Chimie des Materiaux, Departement de Chimie, FST Errachidia, University Moulay Ismail, B.P. 509 Boutalamine, Errachidia (Morocco); Abdalslam, Mouner Ahmed [Materials Science, Technical University Darmstadt, Darmstadt (Germany); Ehrenberg, Helmut [IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany)

    2011-01-28

    Graphical abstract: A perspective view of the Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3} structure along the [0 0 1] direction. Both compounds seem to exibit antiferromagnetic interactions between magnetic entities at low temperature. Display Omitted Research highlights: > Nasicon and Alluaudite compounds, Iron(III)-based phosphates, Crystal structures of Na{sub 4}NiFe(PO{sub 4}){sub 3} and Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3}. > Magnetism behaviours of Na{sub 4}NiFe(PO{sub 4}){sub 3} and Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3}. > Antiferromagnetism interactions. > Mossbauer spectroscopy. - Abstract: Crystal structures from two new phosphates Na{sub 4}NiFe(PO{sub 4}){sub 3} (I) and Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3} (II) have been determined by single crystal X-ray diffraction analysis. Compound (I) crystallizes in a rhombohedral system (S. G: R-3c, Z = 6, a = 8.7350(9) A, c = 21.643(4) A, R{sub 1} = 0.041, wR{sub 2}=0.120). Compound (II) crystallizes in a monoclinic system (S. G: C2/c, Z = 4, a = 11.729(7) A, b = 12.433(5) A, c = 6.431(2) A, {beta} = 113.66(4){sup o}, R{sub 1} = 0.043, wR{sub 2}=0.111). The three-dimensional structure of (I) is closely related to the Nasicon structural type, consisting of corner sharing [(Ni/Fe)O{sub 6}] octahedra and [PO{sub 4}] tetrahedra forming [NiFe(PO{sub 4}){sub 3}]{sup 4+} units which align in chains along the c-axis. The Na{sup +} cations fill up trigonal antiprismatic sites within these chains. The crystal structure of (II) belongs to the alluaudite type. Its open framework results from [Ni{sub 2}O{sub 10}] units of edge-sharing [NiO{sub 6}] octahedra, which alternate with [FeO{sub 6}] octahedra that form infinite chains. Coordination of these chains yields two distinct tunnels in which site Na{sup +}. The magnetization data of compound (I) reveal antiferromagnetic (AFM) interactions by the onset of deviations from a Curie-Weiss behaviour at low temperature as confirmed by Moessbauer measurements performed at 4.2 K. The

  18. 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

  19. 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

  20. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  2. Experimental Thermodynamics of [Na-Mg-Cl-SO4] Aqueous Solutions at GPa Pressure With Application to Icy Worlds.

    Science.gov (United States)

    Brown, J. M.; Bollengier, O.; Vance, S.

    2017-12-01

    Water competes with silicates as the main constituent of solid bodies in the outer solar system. Ganymede and Titan, the Mercury-sized satellites of Jupiter and Saturn, are made up half of water present as massive hydrospheres where pressure can reach up to 1.5 GPa. Geophysical data and planetary models unequivocally support the existence of global aqueous oceans trapped in these hydrospheres. However, the extent of these oceans and their role in the processes governing the internal structure of these moons remain unresolved. At issue is the poor to non-existent characterization, at the relevant pressures, of the properties of the aqueous fluids of significance to the outer solar system (with notably the Na-Mg-Cl-SO4 salts found in primitive chondrites), forcing current models to rely on pure water only. Our team at the University of Washington has developed an experimental apparatus to acquire the speed of sound of aqueous solutions in the 0 - 0.7 GPa and 250 - 350 K pressure and temperature ranges covering most of the conditions of existence of these extra-terrestrial oceans. Speeds of sound measured over a grid of pressures and temperatures allow calculation of the thermodynamic quantities (G, ρ, μ...) required for planetary science. Early analysis of pure water samples indicates our experimental results are on par with (at lower pressures), or better than, the IAPWS water laboratory standard, with sound speeds determined to 0.02% over our entire pressure range. For the first time at the high pressures of interest for large icy moons, we achieved the exploration of H2O-NaCl, H2O-MgSO4, H2O-Na2SO4 and H2O-MgCl2 solutions, from dilute concentrations to saturation. We are now in the process of acquiring the first data for H2O-NaCl-MgSO4 mixtures. We will briefly present our experimental setup and the underlying sound speed theory, and will then compare our results for the four endmembers, with an emphasis on their different association behavior under pressure as

  3. 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

  4. 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)

  5. 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.

  6. Manipulation of perpendicular magnetic anisotropy of single Fe atom adsorbed graphene via MgO(1 1 1) substrate

    Science.gov (United States)

    Fu, Mingming; Tang, Weiqing; Wu, Yaping; Ke, Congming; Guo, Fei; Zhang, Chunmiao; Yang, Weihuang; Wu, Zhiming; Kang, Junyong

    2018-05-01

    Perpendicular magnetic anisotropy is significantly important for realizing a long-term retention of information for spintronics devices. Inspired by 2D graphene with its high charge carrier mobility and long spin diffusion length, we report a first-principles design framework on perpendicular magnetic anisotropy engineering of a Fe atom adsorbed graphene by employing a O-terminated MgO (1 1 1) substrate. Determined by the adsorption sites of the Fe atom, a tunable magnetic anisotropy is realized in Fe/graphene/MgO (1 1 1) structure, with the magnetic anisotropy energy of  ‑0.48 meV and 0.23 meV, respectively, corresponding to the in-plane and out of plane easy magnetizations. Total density of states suggest a half-metallicity with a 100% spin polarization in the system. Decomposed densities of Fe-3d states reveal the orbital contributions to the magnetic anisotropy for different Fe adsorption sites. Bonding interaction and charge redistribution regulated by MgO substrate are found responsible for the novel perpendicular magnetic anisotropy engineering in the system. The effective manipulation of perpendicular magnetic anisotropy in present work offers some references for the design and construction of 2D spintronics devices.

  7. Effect of carbons (G and CFs), TM (Ni, Fe and Al) and oxides (Nb_2O_5 and V_2O_5) on hydrogen generation from ball milled Mg-based hydrolysis reaction for fuel cell

    International Nuclear Information System (INIS)

    Awad, A.S.; El-Asmar, E.; Tayeh, T.; Mauvy, F.; Nakhl, M.; Zakhour, M.; Bobet, J.-L.

    2016-01-01

    This paper dedicated to investigation the effect of carbons (graphite and carbon fibers), transition metals (TM = Ni, Fe and Al) and oxides (Nb_2O_5 and V_2O_5) on Mg–H hydrolysis reaction in aqueous media (3.5 wt% NaCl). Mg – 10 wt% X (X = C, TM and oxides) mixtures were prepared by mechanical milling (1, 3 and 5 h). Mg – 10 wt% G mixtures show the best hydrolysis performance (95% of theoretical hydrogen generation yield in almost 3 min) in comparison to Mg – oxide and Mg – TM mixtures. In addition to the presence of micro-galvanic cells, particle size, MgH_2 content, density defects, fractures and cracking have an important influence on the hydrolysis reaction. Synergetic effect of carbons and transition metals has been studied for Mg – 5 wt% G – 5 wt% Ni mixture. Activation energies were calculated using Avrami–Erofeev model. An activation energy of 14.34 kJ/mol was found for Mg/G/Ni mixture which demonstrates the best hydrolysis behavior (95% of theoretical hydrogen generation yield within 2 min). Hydrogen generated from Mg–H hydrolysis reaction was fed directly to a single Proton Exchange Membrane Fuel Cell (PEMFC). At 0.15 A, the cell voltage exhibited a stable value of approximately 0.52 V for roughly 35 min. - Highlights: • The presence of carbon and transition metals enhance the hydrolysis reaction of magnesium. • The synergetic effect of graphite and Ni leads to the best hydrolysis kinetics. • Cl"− ions replace OH"− ions to destabilize the Mg(OH)_2 passivation layer. • Production of electricity is feasible from hydrogen generated from Mg.

  8. 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.

  9. Giant negative thermal expansion in NaZn13-type La(Fe, Si, Co)13 compounds.

    Science.gov (United States)

    Huang, Rongjin; Liu, Yanying; Fan, Wei; Tan, Jie; Xiao, Furen; Qian, Lihe; Li, Laifeng

    2013-08-07

    La(Fe, Si)13-based compounds are well-known magnetocaloric materials, which show a pronounced negative thermal expansion (NTE) around the Curie temperature but have not been considered as NTE materials for industrial applications. The NaZn13-type LaFe13-xSix and LaFe11.5-xCoxSi1.5 compounds were synthesized, and their linear NTE properties were investigated. By optimizing the chemical composition, the sharp volume change in La(Fe, Si)13-based compounds was successfully modified into continuous expansion. By increasing the amount of Co dopant in LaFe11.5-xCoxSi1.5, the NTE shifts toward a higher temperature region, and also the NTE operation-temperature window becomes broader. Typically, the linear NTE coefficient identified in the LaFe10.5Co1.0Si1.5 compound reaches as much as -26.1 × 10(-6) K(-1), with an operation-temperature window of 110 K from 240 to 350 K, which includes room temperature. Such control of the specific composition and the NTE properties of La(Fe, Si)13-based compounds suggests their potential application as NTE materials.

  10. Preparation of high-strength Al-Mg-Si-Cu-Fe alloy via heat treatment and rolling

    Science.gov (United States)

    Liu, Chong-yu; Yu, Peng-fei; Wang, Xiao-ying; Ma, Ming-zhen; Liu, Ri-ping

    2014-07-01

    An Al-Mg-Si-Cu-Fe alloy was solid-solution treated at 560°C for 3 h and then cooled by water quenching or furnace cooling. The alloy samples which underwent cooling by these two methods were rolled at different temperatures. The microstructure and mechanical properties of the rolled alloys were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, and tensile testing. For the water-quenched alloys, the peak tensile strength and elongation occurred at a rolling temperature of 180°C. For the furnace-cooled alloys, the tensile strength decreased initially, until the rolling temperature of 420°C, and then increased; the elongation increased consistently with increasing rolling temperature. The effects of grain boundary hardening and dislocation hardening on the mechanical properties of these rolled alloys decreased with increases in rolling temperature. The mechanical properties of the 180°C rolling water-quenched alloy were also improved by the presence of β″ phase. Above 420°C, the effect of solid-solution hardening on the mechanical properties of the rolled alloys increased with increases in rolling temperature.

  11. 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.

  12. 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.

  13. 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

  14. Seasonal variation of major elements (Ca, Mg) and trace metals (Fe, Cu, Zn, Mn) and cultured mussel Perna viridis L. and seawater in the Dona Paula Bay, Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Rivonker, C.U.; Parulekar, A.H.

    The major elements and trace metals were analysed from nussel tissue and the seawater taken from three depths (0, 5 and 9 meters) from the culture site. Range of variation in Ca, Mg, Fe, Cu, Zn and Mn were 226-399; 708-1329; 0.005-0.084; BDL-0...

  15. Effect of Drying Conditions on the Catalytic Performance, Structure, and Reaction Rates over the Fe-Co-Mn/MgO Catalyst for Production of Light Olefins

    Directory of Open Access Journals (Sweden)

    Majid Abdouss

    2018-01-01

    How to Cite: Abdouss, M., Arsalanfar, M., Mirzaei, N., Zamani, Y. (2018. Effect of Drying Conditions on the Catalytic Performance, Structure, and Reaction Rates over the Fe-Co-Mn/MgO Catalyst for Production of Light Olefins. Bulletin of Chemical Reaction Engineering & Catalysis, 13 (1: 97-112 (doi:10.9767/bcrec.13.1.1222.97-112

  16. O Que se Compra na Feira? Perfil e Fatores de Decisao do Consumidor em Lavras, MG.

    OpenAIRE

    Silvestre, Luiz Henrique; Neto, Exzolvildres Queiroz; Calixto, Juliana Sena; Ramos, Rosana Vieira; Antonialli, Luiz Marcelo

    2006-01-01

    O mercado local não é apenas um espaço de venda de produtos, mas também de garantia da segurança alimentar, de fortalecimento da pequena agricultura e de dinamização econômica por reter por mais tempo o recurso no município, fazendo-o circular entre a população local, possibilitando a satisfação das necessidades. Mas o que os consumidores compram na feira? A opção de ir a feira está ligada apenas a aquisição de alimentos ou há outras características que os consumidores também compram? Quais s...

  17. 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

  18. Vacuum ultraviolet synchrotron measurements of excitons in NaMgF{sub 3}:Yb{sup 2+}

    Energy Technology Data Exchange (ETDEWEB)

    Hughes-Currie, Rosa B. [Department of Physics and Astronomy, University of Canterbury, PB 4800, Christchurch 8140 (New Zealand); Ivanovskikh, Konstantin V. [ANK Service Ltd., PB 58, Novouralsk 624131, Sverdlovsk Region (Russian Federation); Ural Federal University, 19 Mira st., Ekaterinburg 620002 (Russian Federation); Reid, Michael F., E-mail: mike.reid@canterbury.ac.nz [Department of Physics and Astronomy, University of Canterbury, PB 4800, Christchurch 8140 (New Zealand); MacDiarmid Institute for Advanced Materials and Nanotechnology (New Zealand); Wells, Jon-Paul R. [Department of Physics and Astronomy, University of Canterbury, PB 4800, Christchurch 8140 (New Zealand); Dodd-Walls Centre for Quantum and Photonic Technologies (New Zealand); Reeves, Roger J. [Department of Physics and Astronomy, University of Canterbury, PB 4800, Christchurch 8140 (New Zealand); MacDiarmid Institute for Advanced Materials and Nanotechnology (New Zealand); Meijerink, Andries [Debye Institute, Utrecht University, P.O. Box 80 000, 3508 TA Utrecht (Netherlands)

    2016-01-15

    Results of a vacuum ultraviolet spectroscopic characterization of NaMgF{sub 3}:Yb{sup 2+} are presented. The material demonstrates emission features associated with self-trapped excitons and impurity-trapped excitons. The emission features noticeably overlap giving rise to a broad emission band from 17 000 to 35 000 cm{sup −1} at a sample temperature of 8 K. To identify the true profiles of the emission features we have used a deconvolution procedure. The deconvolution was possible due to the thermal quenching of self-trapped excitons at room temperature that allowed for direct observations of the impurity trapped exciton emission band. Energy transfer between host electronic excitations (excitons and e–h pairs) and Yb{sup 2+} ions leading to the formation of impurity-trapped excitons is evident from excitation spectra. - Highlights: • We present VUV emission and excitation spectra of NaMgF{sub 3}:Yb{sup 2+}. • Formation of free excitons leads to emission from intrinsic and extrinsic excitons. • We deconvolute the emission to separate the two overlapping exciton bands. • The excitation spectra show two mechanisms for forming impurity-trapped excitons.

  19. (e, 2e) triple differential cross sections of alkali and alkali earth atoms: Na, K and Mg, Ca

    International Nuclear Information System (INIS)

    Hitawala, U; Purohit, G; Sud, K K

    2008-01-01

    Recently low-energy measurements have been reported for alkali targets Na and K and alkali earth targets Mg and Ca in coplanar symmetric geometry. We report the results of our calculation of triple differential cross section (TDCS) for electron impact single ionization (i.e. (e, 2e) processes) of alkali atoms Na, K and alkali earth atoms Mg, Ca in coplanar symmetric geometry. We have performed the present calculations using the distorted-wave Born approximation (DWBA) formalism at intermediate incident electron energies used in the recently performed experiments. Ionization takes place from the valence shell for all the targets investigated and the outgoing electrons share the excess energy equally. We have also considered the effect of target polarization in our DWBA calculations which may be an important quantity at incident electron energies used in the present investigation. We find that the DWBA formalism is able to reproduce most of the trend of experimental data and may provide a future direction for further investigation of ionization process on alkali and alkali earth metals. It is also observed that the second-order effects are more important to understand the collision dynamics of (e, 2e) processes on alkali earth targets

  20. Rich magnetoelectric phase diagrams of multiferroic single-crystal α -NaFeO2

    Science.gov (United States)

    Terada, Noriki; Ikedo, Yuta; Sato, Hirohiko; Khalyavin, Dmitry D.; Manuel, Pascal; Miyake, Atsushi; Matsuo, Akira; Tokunaga, Masashi; Kindo, Koichi

    2017-07-01

    The magnetic and dielectric properties of the multiferroic triangular lattice magnet compound α -NaFeO2 were studied by magnetization, specific heat, dielectric permittivity, and pyroelectric current measurements and by neutron diffraction experiments using single crystals grown by a hydrothermal synthesis method. This work produced magnetic field (in the monoclinic a b -plane, Ba b, and along the c*-axis, Bc) versus temperature magnetic phase diagrams, including five and six magnetically ordered phases in Ba b and along Bc, respectively. In zero magnetic field, two spin-density-wave orderings with different k vectors—(0 ,q ,1/2 ) in phase I and (qa,qb,qc ) in phase II—appeared at T =9.5 and 8.25 K, respectively. Below T =5 K, a commensurate order with k =(0.5 ,0 ,0.5 ) was stabilized as the ground state in phase III. Both Ba b≥3 T and Bc≥5 T were found to induce ferroelectric phases at the lowest temperature (2 K), with an electric polarization that was not confined to any highly symmetric directions in phases IVa b (3.3 ≤Ba b≤8.5 T), Va b (8.5 ≤Ba b≤13.6 T), IVc (5.0 ≤Bc≤8.5 T), and Vc (8.5 ≤Bc≤13.5 T). In phase VIc, within a narrow temperature region in Bc, the polarization was confined to the a b plane. For each of the ferroelectric phases, the k vector was (qa,qb,qc ), and noncollinear structures were identified, including a general spiral in IVa b an a b cycloid in IVc and Vc, and a proper screw in VIc, along with a triclinic 11' magnetic point group allowing polarization in the general direction. Comparing the polarization direction to the magnetic structures in the ferroelectric phases, we conclude that the extended inverse Dzyaloshinskii-Moriya mechanism expressed by the orthogonal components p1∝ri j×(Si×Sj) and p2∝Si×Sj can explain the polarization directions. Based on calculations incorporating exchange interactions up to fourth-nearest-neighbor (NN) couplings, we infer that competition among antiferromagnetic second NN

  1. 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

  2. Effects of hyper- and hypothyroidism on acetylcholinesterase, (Na(+), K (+))- and Mg ( 2+ )-ATPase activities of adult rat hypothalamus and cerebellum.

    Science.gov (United States)

    Carageorgiou, Haris; Pantos, Constantinos; Zarros, Apostolos; Stolakis, Vasileios; Mourouzis, Iordanis; Cokkinos, Dennis; Tsakiris, Stylianos

    2007-03-01

    Thyroid hormones (THs) are recognized as key metabolic hormones, and the metabolic rate increases in hyperthyroidism, while it decreases in hypothyroidism. The aim of this work was to investigate how changes in metabolism induced by THs could affect the activities of acetylcholinesterase (AChE), (Na(+), K(+))- and Mg(2+)-ATPase in the hypothalamus and the cerebellum of adult rats. Hyperthyroidism was induced by subcutaneous administration of thyroxine (25 microg/100 g body weight) once daily for 14 days, while hypothyroidism was induced by oral administration of propylthiouracil (0.05%) for 21 days. All enzyme activities were evaluated spectrophotometrically in the homogenated brain regions of 10 three-animal pools. Neither hyper-, nor hypothyroidism had any effect on the examined hypothalamic enzyme activities. In the cerebellum, hyperthyroidism provoked a significant decrease in both the AChE (-23%, p activities (-26%, p activities: AChE (-17%, p activity was found unaltered in both the hyper- and the hypothyroid brain regions. neither hyper-, nor hypothyroidism had any effect on the examined hypothalamic enzyme activities. In the cerebellum, hyperthyroidism provoked a significant decrease in both the AChE and the Na(+), K(+)-ATPase activities. The decreased (by the THs) Na(+), K(+)-ATPase activities may increase the synaptic acetylcholine release, and thus, could result in a decrease in the cerebellar AChE activity. Moreover, the above TH-induced changes may affect the monoamine neurotransmitter systems.

  3. Effect of oxide films, inclusions and Fe on reproducibility of tensile properties in cast Al–Si–Mg alloys: Statistical and image analysis

    International Nuclear Information System (INIS)

    Eisaabadi B, G.; Davami, P.; Kim, S.K.; Varahram, N.; Yoon, Y.O.; Yeom, G.Y.

    2012-01-01

    Double oxide films (hereafter: oxides), inclusions and Fe-rich phases are known to be the most detrimental defects in cast Al–Si–Mg alloys. The effects of these defects on reproducibility of tensile properties in Al–7Si–0.35Mg alloy have been investigated in this study. Four different casting conditions (low oxide—low Fe, high oxide—low Fe, low oxide—high Fe and high oxide—high Fe) were studied. In each case, 30 tensile test samples were prepared by casting in a metallic mold and machining (total of 120 tensile test samples). Results of tensile test were analyzed by Weibull three-parameter and mixture analyses. The microstructure and fracture surface of samples were studied by optical and scanning electron microscopes. Total of 800 metallography images (200 images for each experiment) were taken and analyzed by image analysis software. Finally, the relationship between tensile properties and defects characteristics was discussed. According to the results, Fe (Fe-related phases) had larger negative impact on tensile properties of the alloy compared to oxides. On the other hand, Weibull analysis revealed that the scattering of tensile properties was mainly due to the presence of oxides in microstructure. Results of image analysis showed that the shape factor and number of pores were mainly controlled by oxides and Fe, respectively. Also, there was a clear relationship between Weibull modules of UTS and El% and shape factor of pores. Furthermore, tensile properties of the examined alloy showed strong dependence to the number of pores.

  4. Elastic wave velocities of iron-bearing Ringwoodite (Mg0.8Fe0.2)2SiO2 to 12GPa at room temperature

    Science.gov (United States)

    Higo, Y.; Li, B.; Inoue, T.; Irifune, T.; Libermann, R. C.

    2002-12-01

    At present, it is widely accepted that olivine is the most important mineral in the Earth's upper mantle. The elastic property changes associated with the phase transformations to its high-pressure polymorphs are very important parameters to constrain the composition of the mantle transition zone. In this study, we measured the elastic wave velocity of iron-bearing Ringwoodite (Mg0.8Fe0.2)2SiO4. The specimen was hot-pressed at 18GPa and 1273K in a 2000-ton Uniaxial Split Sphere Apparatus (ORANGE-2000: GRC at ehime university). The recovered polycrystalline specimen was characterized by x-ray diffraction, EPMA, ultrasonic techniques, and the density was determined by Archimedes' method, and found to be single-phase and fine-grained. Bench top measurements of the compressional and shear wave velocities yielded Vp=9.10 km/s and Vs=5.52 km/s. High-pressure ultrasonic measurement was carried out in a 1000-ton Uniaxial Split-Cylinder Apparatus (USCA-1000: SUNY) at pressures up to 12GPa at room temperature using ZnTe as internal pressure marker. The sample was surrounded by lead to minimize the deviatoric stress. Also in this experiment, the travel times of the Al2O3 buffer rod were used for pressure calculation. The travel times of the buffer rod under the same cell geometry have been calibrated as a function of sample pressure by the thermal equation of state of NaCl using in-situ X-ray diffraction techniques. The results of our high-pressure experiment, including the elastic moduli and their pressure dependence, effect of iron on the elastic moduli, as well as their implication for the mantle transition zone, will be presented.

  5. Role of iron in Na {sub 1.5}Fe {sub 0.5}Ti {sub 1.5}(PO {sub 4}) {sub 3}/C as electrode material for Na-ion batteries studied by operando Mössbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Difi, Siham [Université de Montpellier, Institut Charles Gerhardt, UMR 5253 CNRS (France); Saadoune, Ismael [Université Cadi Ayyad, Laboratoire de Chimie des Matériaux et de l’Environnement (Morocco); Sougrati, Moulay Tahar [Université de Montpellier, Institut Charles Gerhardt, UMR 5253 CNRS (France); Hakkou, Rachid [Université Cadi Ayyad, Laboratoire de Chimie des Matériaux et de l’Environnement (Morocco); Edstrom, Kristina [Uppsala University, Department of Chemistry - Ångström laboratory (Sweden); Lippens, Pierre-Emmanuel, E-mail: lippens@univ-montp2.fr [Université de Montpellier, Institut Charles Gerhardt, UMR 5253 CNRS (France)

    2016-12-15

    The role of iron in Na {sub 1.5}Fe {sub 0.5}Ti {sub 1.5}(PO {sub 4}){sub 3}/C electrode material for Na batteries has been studied by {sup 57}Fe Mössbauer spectroscopy in operando mode. The potential profile obtained in the galvanostatic regime shows three plateaus at different voltages due to different reaction mechanisms. Two of them, at 2.2 and 0.3 V vs Na {sup +}/Na {sup 0}, have been associated to redox processes involving iron and titanium in Na {sub 1.5}Fe {sub 0.5}Ti {sub 1.5}(PO {sub 4}){sub 3}. The role of titanium was previously elucidated for NaTi {sub 2}(PO {sub 4}){sub 3} and the effect of the substitution of Fe for Ti was investigated with {sup 57}Fe Mössbauer spectroscopy. We show that iron is an electrochemically active center at 2.2 V with the reversible Fe {sup 3+}/Fe {sup 2+} transformation and then remains at the oxidation state Fe {sup 2+} along the sodiation until the end of discharge at 0 V.

  6. 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.

  7. 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.

  8. Periodic DFT study of acidic trace atmospheric gas molecule adsorption on Ca- and Fe-doped MgO(001) surface basic sites.

    Science.gov (United States)

    Baltrusaitis, Jonas; Hatch, Courtney; Orlando, Roberto

    2012-08-02

    The electronic properties of undoped and Ca- or Fe-doped MgO(001) surfaces, as well as their propensity toward atmospheric acidic gas (CO2, SO2, and NO2) uptake was investigated with an emphasis on gas adsorption on the basic MgO oxygen surface sites, O(surf), using periodic density functional theory (DFT) calculations. Adsorption energy calculations show that MgO doping will provide stronger interactions of the adsorbate with the O(surf) sites than the undoped MgO for a given adsorbate molecule. Charge transfer from the iron atom in Fe-doped MgO(001) to NO2 was shown to increase the binding interaction between adsorbate by an order of magnitude, when compared to that of undoped and Ca-doped MgO(001) surfaces. Secondary binding interactions of adsorbate oxygen atoms were observed with surface magnesium sites at distances close to those of the Mg-O bond within the crystal. These interactions may serve as a preliminary step for adsorption and facilitate further adsorbate transformations into other binding configurations. Impacts on global atmospheric chemistry are discussed as these adsorption phenomena can affect atmospheric gas budgets via altered partitioning and retention on mineral aerosol surfaces.

  9. Enhancing anaerobic digestion of waste activated sludge by the combined use of NaOH and Mg(OH)2: Performance evaluation and mechanism study.

    Science.gov (United States)

    Huang, Cheng; Lai, Jia; Sun, Xiuyun; Li, Jiansheng; Shen, Jinyou; Han, Weiqing; Wang, Lianjun

    2016-11-01

    In this study, the combination treatment of NaOH and Mg(OH)2 was applied to anaerobic digestion of waste activated sludge (WAS) for simultaneously enhancement of volatile fatty acids (VFAs) production, nutrients removal and sludge dewaterability. The maximum VFAs production (461mg COD/g VSS) was obtained at the NaOH/Mg(OH)2 ratio of 75:25, which was much higher than that of the blank or sole NaOH. Moreover, nutrients removal and sludge dewaterability were improved by the combined using of NaOH and Mg(OH)2. Mechanism investigations revealed that the presence of Mg(OH)2 could maintain alkaline environment, which contributed to inhibit the activity of methanogens. Also, the bridging between Mg(2+) and extracellular polymeric substances (EPS) plays an important role in the solubilization and dewatering of sludge. High-throughput sequencing analysis demonstrated that the abundance of bacteria involved in sludge hydrolysis and VFAs accumulation was greatly enriched with the mixtures of NaOH and Mg(OH)2. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. A comparative corrosion behavior of Mg, AZ31 and AZ91 alloys in 3.5% NaCl solution

    Directory of Open Access Journals (Sweden)

    I.B. Singh

    2015-06-01

    Full Text Available The corrosion behavior of Mg, AZ31 and AZ91 has been evaluated in 3.5% NaCl solution using weight loss, electrochemical polarization and impedance measurements. Corrosion rate derived from the weight losses demonstrated the occurrence of steeply fast corrosion reaction on AZ91 alloy after three hours of immersion, indicating the start of galvanic corrosion. An increase of corrosion rate with immersion time was also observed for AZ31 but with lesser extent than AZ91 alloy. Whereas Mg metals showed a decrease of corrosion rate with immersion time, suggesting the formation of a protective layer on their surfaces. In contrast, the corrosion current density (Icorr derived from the Tafel plots, exhibited their corrosion resistances in order of Mg > AZ91 > AZ31. Electrochemical charge transfer resistance (Rct and double layer capacitance measured by electrochemical impedance spectroscopy (EIS, are well in accordance with the measured Icorr. EIS measurements with time and microstructural examination of the corroded and uncorroded samples are helpful in elucidation of results measured by electrochemical polarization.

  11. GRANDES EMPREENDIMENTOS HABITACIONAIS NA CIDADE DE UBERLÂNDIA – MG

    Directory of Open Access Journals (Sweden)

    Ivone Tavares Batista

    2017-10-01

    Article present search demonstrate and match some forms of occupation of urban land space, where real estate projects with government partnerships bring to the municipalities the housing, which will mainly contemplate the low-income population, may provide these quality a dignified life. This work aims to analyze the housing developments of social interest implanted over decades in the city of Uberlândia using as main methodology searches files of the City Hall of Uberlândia resulting in the number of families served by the popular housing programs, realizing how much is necessary expansion of public policies in relation to home ownership. It was highlighted as analyzed in the great enterprise implant in Sector South of the city, called Shopping Park III, IV, V, VI and VII, which contributed to the reduction of homelessness in the city of Uberlândia - MG. Keywords: Urban Space; Housing Estates; Illegal Occupation; Government. RESUMEN El presente artículo busca demostrar y equipar algunas formas de ocupación del espacio territorial urbano, donde los emprendimientos inmobiliarios en alianzas con el Gobierno, traen a los municipios los conjuntos habitacionales, que van a comportarse principalmente a la población de bajos ingresos. Este trabajo objetiva analizar los emprendimientos habitacionales de interés social implantados a lo largo de décadas en la ciudad de Uberlândia utilizando como metodología principal investigaciones archivos del Ayuntamiento Municipal de Uberlândia dando como resultado el número de familias atendidas por los programas de vivienda popular, percibiendo cuán necesaria es la expansión de las políticas públicas en relación a la casa propia. Se destacó como objeto de análisis el gran emprendimiento implantado en el Sector Sur de la ciudad, denominado de Shopping Park III, IV, V, VI y VII, que colaboró para la disminución de la falta de vivienda en el Municipio de Uberlândia - MG. Palabras clave: Espacio Urbano; Conjuntos

  12. Exigências nutricionais em macronutrientes minerais (Ca, P, Mg, Na e K para novilhos de diferentes grupos genéticos Macrominerals (Ca, P, Mg, Na, and K requirements for young bulls from different genetic groups

    Directory of Open Access Journals (Sweden)

    Fernando de Paula Leonel

    2006-04-01

    Full Text Available Determinaram-se as exigências em macronutrientes minerais (Ca, P, Mg, Na e K utilizando-se 44 novilhos não-castrados, pertencentes a quatro grupos genéticos (Nelore; F1 Nelore x Aberdeen-Angus; F1 Nelore x Pardo-Suíço e F1 Nelore x Simental, com média de 10 e 11 meses de idade e peso vivo inicial de 362 ± 35 kg. A ração experimental foi composta de feno de capim-braquiária (Brachiaria decumbens, Stapf., farelo de soja, milho (grão moído, melaço em pó e suplementos de macro e micronutrientes inorgânicos. As exigências líquidas para ganho de peso, em cada macronutriente, foram obtidas por meio da derivada primeira de suas respectivas equações, estimadas a partir de regressão não-linear do conteúdo do nutriente (Ca, P, Mg, Na e K, em função do peso de corpo vazio do animal. Para conversão do peso vivo em peso de corpo vazio, utilizou-se a equação obtida a partir da regressão do peso corporal vazio dos animais experimentais em função de seus pesos imediatamente antes do abate. As exigências de mantença foram estimadas de acordo com as recomendações do NRC e ARC e os coeficientes de absorção adotados para os cinco macronutrientes foram aqueles propostos pelo ARC. O teste de identidade de modelos indicou não haver diferenças entre as equações de regressão para os minerais entre os quatro grupos genéticos estudados. Não foram verificadas, pela análise de variância, diferenças entre as exigências de macrominerais entre os diferentes grupos genéticos.The objective of this trial was to determine the macrominerals requirements (Ca, P, Mg, Na, and K for young bulls from different genetic groups. Forty-four young bulls from the following genetic groups were used: Nellore, F1 Nellore x Aberdeen-Angus, F1 Nellore x Brown Swiss, and F1 Nellore x Simmental. Animals averaged 362 ± 35 kg of initial body weight and between 10 to 11 months of age. Diet contained signal grass hay (Brachiaria decumbens, Stapf., soybean

  13. Abnormal thermal expansion properties of cubic NaZn13-type La(Fe,Al)13 compounds.

    Science.gov (United States)

    Li, Wen; Huang, Rongjin; Wang, Wei; Zhao, Yuqiang; Li, Shaopeng; Huang, Chuanjun; Li, Laifeng

    2015-02-28

    The cubic NaZn13-type La(Fe,Al)13 compounds were synthesized, and their linear thermal expansion properties were investigated in the temperature range of 4.2-300 K. It was found that these compounds exhibit abnormal thermal expansion behavior, i.e., pronounced negative thermal expansion (NTE) or zero thermal expansion (ZTE) behavior, below the Curie temperature due to the magnetovolume effect (MVE). Moreover, in the La(Fe,Al)13 compounds, the modification of the coefficient of thermal expansion (CTE) as well as the abnormal thermal expansion (ATE) temperature-window is achieved through optimizing the proportion of Fe and Al. Typically, the average CTE of the LaFe13-xAlx compounds with x = 1.8 reaches as large as -10.47 × 10(-6) K(-1) between 100 and 225 K (ΔT = 125 K). Also, the ZTE temperature-window of the LaFe13-xAlx compounds with x = 2.5 and x = 2.7 could be broadened to 245 K (from 5 to 250 K). Besides, the magnetic properties of these compounds were measured and correlated with the abnormal thermal expansion behavior. The present results highlight the potential application of such La(Fe,Al)13 compounds with abnormal thermal expansion properties in cryogenic engineering.

  14. High-Energy-Density Aqueous Magnesium-Ion Battery Based on a Carbon-Coated FeVO4 Anode and a Mg-OMS-1 Cathode.

    Science.gov (United States)

    Zhang, Hongyu; Ye, Ke; Zhu, Kai; Cang, Ruibai; Yan, Jun; Cheng, Kui; Wang, Guiling; Cao, Dianxue

    2017-12-01

    Porous FeVO 4 is prepared by hydrothermal method and further modified by coating with carbon to obtain FeVO 4 /C with a hierarchical pore structure. FeVO 4 /C is used as an anodic electrode in aqueous rechargeable magnesium-ion batteries. The FeVO 4 /C material not only has improved electrical conductivity as a result of the carbon coating layer, but also has an increased specific surface area as a result of the hierarchical pore structure, which is beneficial for magnesium-ion insertion/deinsertion. Therefore, an aqueous rechargeable magnesium-ion full battery is successfully constructed with FeVO 4 /C as the anode, Mg-OMS-1 (OMS=octahedral molecular sieves) as the cathode, and 1.0 mol L -1 MgSO 4 as the electrolyte. The discharge capacity of the Mg-OMS-1//FeVO 4 /C aqueous battery is 58.9 mAh g -1 at a current density of 100 mA g -1 ; this value is obtained by calculating the total mass of two electrodes and the capacity retention rate of this device is 97.7 % after 100 cycles, with almost 100 % coulombic efficiency, which indicates that the system has a good electrochemical reversibility. Additionally, this system can achieve a high energy density of 70.4 Wh kg -1 , which provides powerful evidence that an aqueous magnesium-ion battery is possible. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Effects of aqueous extract of Hibiscus sabdariffa on renal Na(+)-K(+)-ATPase and Ca(2+)-Mg(2+)-ATPase activities in Wistar rats.

    Science.gov (United States)

    Olatunji, Lawrence A; Usman, Taofeek O; Adebayo, Joseph O; Olatunji, Victoria A

    2012-09-01

    To investigate the effects of oral administration of aqueous extract of Hibiscus sabdariffa on renal Na(+)-K(+)-ATPase and Ca(2+)-Mg(2+)-ATPase activities in rats. The 25 and 50 mg/(kg·d) of aqueous extracts of H. sabdariffa were respectively given to rats in the experimental groups for 28 d, and rats in the control group received an appropriate volume of distilled water as vehicle. Na(+)-K(+)-ATPase and Ca(2+)-Mg(2+)-ATPase activities in the kidney were assayed by spectrophotometric method. Administrations of 25 and 50 mg/(kg·d) of aqueous extract of H. sabdariffa significantly decreased the Ca(2+)-Mg(2+)-ATPase activity in the kidney of rats (Psabdariffa may preserve the renal function despite a decreased renal Ca(2+)-Mg(2+)-ATPase activity.

  16. Mesoporous carbon-coated LiFePO4 nanocrystals co-modified with graphene and Mg2+ doping as superior cathode materials for lithium ion batteries.

    Science.gov (United States)

    Wang, Bo; Xu, Binghui; Liu, Tiefeng; Liu, Peng; Guo, Chenfeng; Wang, Shuo; Wang, Qiuming; Xiong, Zhigang; Wang, Dianlong; Zhao, X S

    2014-01-21

    In this work, mesoporous carbon-coated LiFePO4 nanocrystals further co-modified with graphene and Mg(2+) doping (G/LFMP) were synthesized by a modified rheological phase method to improve the speed of lithium storage as well as cycling stability. The mesoporous structure of LiFePO4 nanocrystals was designed and realized by introducing the bead milling technique, which assisted in forming sucrose-pyrolytic carbon nanoparticles as the template for generating mesopores. For comparison purposes, samples modified only with graphene (G/LFP) or Mg(2+) doping (LFMP) as well as pure LiFePO4 (LFP) were also prepared and investigated. Microscopic observation and nitrogen sorption analysis have revealed the mesoporous morphologies of the as-prepared composites. X-ray diffraction (XRD) and Rietveld refinement data demonstrated that the Mg-doped LiFePO4 is a single olivine-type phase and well crystallized with shortened Fe-O and P-O bonds and a lengthened Li-O bond, resulting in an enhanced Li(+) diffusion velocity. Electrochemical properties have also been investigated after assembling coin cells with the as-prepared composites as the cathode active materials. Remarkably, the G/LFMP composite has exhibited the best electrochemical properties, including fast lithium storage performance and excellent cycle stability. That is because the modification of graphene provided active sites for nuclei, restricted the in situ crystallite growth, increased the electronic conductivity and reduced the interface reaction current density, while, Mg(2+) doping improved the intrinsically electronic and ionic transfer properties of LFP crystals. Moreover, in the G/LFMP composite, the graphene component plays the role of "cushion" as it could quickly realize capacity response, buffering the impact to LFMP under the conditions of high-rate charging or discharging, which results in a pre-eminent rate capability and cycling stability.

  17. [Effectiveness of social mobilization and social marketing in promoting NaFeEDTA-fortified soya sauce in adult women].

    Science.gov (United States)

    Wang, Bo; Chen, Junshi; Zhan, Siyan; Sun, Jing; Li, Liming

    2011-05-01

    To assess the effectiveness of social mobilization and social marketing in promoting NaFeEDTA-fortified soy sauce in an iron deficient population. This study was an uncontrolled, community-based, before-after study, which was implemented in three counties of Shijiazhuang Municipality. The intervention was a social mobilization and social marketing strategy. Adult women older than 20 years of age participated in the evaluation protocol. The main outcomes included KAP relevant to IDA. Cross-sectional samples were used to assess the outcomes at baseline and 1 year later. Knowledge and attitudes of adult women had changed positively, and the percentage of women who had adopted NaFeEDTA-fortified soy sauce increased from 8.9% to 36.6% (P marketing had a positive impact on the KAP of adult women in the iron deficient population.

  18. Perpendicular magnetic anisotropy at the interface between ultrathin Fe film and MgO studied by angular-dependent x-ray magnetic circular dichroism

    Energy Technology Data Exchange (ETDEWEB)

    Okabayashi, J. [Research Center for Spectrochemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Koo, J. W.; Mitani, S. [National Institute for Materials Science (NIMS), Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8577 (Japan); Sukegawa, H. [National Institute for Materials Science (NIMS), Tsukuba 305-0047 (Japan); Takagi, Y.; Yokoyama, T. [Institute of Molecular Science, Okazaki, Aichi 444-8585 (Japan)

    2014-09-22

    Interface perpendicular magnetic anisotropy (PMA) in ultrathin Fe/MgO (001) has been investigated using angular-dependent x-ray magnetic circular dichroism (XMCD). We found that anisotropic orbital magnetic moments deduced from the analysis of XMCD contribute to the large PMA energies, whose values depend on the annealing temperature. The large PMA energies determined from magnetization measurements are related to those estimated from the XMCD and the anisotropic orbital magnetic moments through the spin-orbit interaction. The enhancement of anisotropic orbital magnetic moments can be explained mainly by the hybridization between the Fe 3d{sub z}{sup 2} and O 2p{sub z} states.

  19. 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.

  20. Phase transformations, ionic conductivity and dipole ordering of NASICON-like double phosphates Na3M2(PO4)3 (M-Sc,Fe,Cr)

    International Nuclear Information System (INIS)

    Kalinin, V.B.

    1990-01-01

    Experimental data obtained using ceramic samples of Na 3 M 2 (PO 4 ) 3 and solid solutions on their basis have been analyzed and generalized. It is shown that isostoichiometry of Na 3 M 2 (PO 4 ) 3 compounds and different types of dipole ordering in their α-phases stimulate investigations of subsolidus regions in the systems Na 3 Sc 2 (PO 4 ) 3 -Na 3 Fe 2 (PO 4 ) 3 , Na 3 Sc 2 (PO 4 ) 3 -Na 3 Cr 2 (PO 4 ) 3 , Na 3 Fe 2 (PO 4 ) 3 -Na 3 Cr 2 (PO 4 ) 3 .It proved possible to detect changes of the properties in case of ferroelectric-antiferroelectric, antiferroelectric-antiferroelectric transitions

  1. 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.

  2. Synthesis and characterization of Cu0.3Zn0.5Mg0.2Fe2O4 nanoparticles as a magnetic drug delivery system

    Science.gov (United States)

    Ansari, Mohammad; Bigham, Ashkan; Hassanzadeh-Tabrizi, S. A.; Abbastabar Ahangar, H.

    2017-10-01

    Mixed spinel ferrite nanoparticles are being applied in biomedical applications due to their biocompatibility, antibacterial activity, particular magnetic and electronic properties with chemical and thermal stabilities. The Cu0.3Zn0.5Mg0.2Fe2O4 nanoparticles are synthesized through the thermal treatment method. Polyvinyl alcohol (PVA) is used as the capping agent to stabilize the particles and prevent their agglomeration. The synthesized nanoparticles are characterized through X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), N2 adsorption-desorption, field emission scanning electron microscopy (FESEM), and transmission electron microscope (TEM). The magnetic characterization is made on a vibrating sample magnetometer (VSM), which displayed super-paramagnetic behavior of the synthesized sample. Potential application of the Cu0.3Zn0.5Mg0.2Fe2O4 nanoparticles as a drug delivery agent is assessed in vitro by estimating their release properties. The obtained results indicate that the amount of ibuprofen (IBU) adsorbed into the nanocarrier of Cu0.3Zn0.5Mg0.2Fe2O4 is 104 mg/g and the drug release is sustained up to 72 h.

  3. Determination of Cl, K, Mg, Mn, Na and V in Brazilian red wine by neutron activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Daniele, Anna Paula; Maihara, Vera Akiko, E-mail: annapaula@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    Several studies have been carried out for determining essential elements in foodstuffs due to important nutritional role in human body functions. Such information is crucial to any intervention in the diet of a population, thus becoming representative in the public health field. Trace elements are good indicators of wine’s origin and their concentrations can be used as criteria to ensure authenticity, quality and show that the tolerance limits established by law were respected throughout the production process. Although Brazilian wine industry is among the 15 largest in the world, analytical studies on the content of organic and inorganic compounds in wine are still small compared to other major producers. This study aimed to evaluate the elemental concentration of Cl, K, Mg, Mn, Na and V in seven national red wine samples acquired in the markets of Sao Paulo city. The analytical method applied was INAA. Concentrations of the elements in wine samples showed high variation among samples. (author)

  4. Band gap opening in silicene on MgBr2(0001) induced by Li and Na

    KAUST Repository

    Zhu, Jiajie

    2014-11-12

    Silicene consists of a monolayer of Si atoms in a buckled honeycomb structure and is expected to be well compatible with the current Si-based technology. However, the band gap is strongly influenced by the substrate. In this context, the structural and electronic properties of silicene on MgBr2(0001) modified by Li and Na are investigated by first-principles calculations. Charge transfer from silicene (substrate) to substrate (silicene) is found for substitutional doping (intercalation). As compared to a band gap of 0.01 eV on the pristine substrate, strongly enhanced band gaps of 0.65 eV (substitutional doping) and 0.24 eV (intercalation) are achieved. The band gap increases with the dopant concentration.

  5. Aspectos epidemiológicos dateníase-cisticercose na área endêmica de Lagamar, MG

    OpenAIRE

    Silva-Vergara, Mario León; Prata, Aluízio; Vieira, Cláudio de Oliveira; Castro, João Henrique; Micheletti, Luciane Giroto; Otaño, Arturo Santana; Franquini Júnior, João

    1995-01-01

    Um inquérito epidemiológico sobre teníase-cisticercose foi realizado em Lagamar- MG em 1992. Cadastradas 1109 casas com 3344 habitantes. O inquérito abrangeu 875 (86%) famílias e foi respondido por um informante que, em 80% dos casos, foi o pai. Na cidade havia 100 chiqueiros em 100 (11,4%) casas que albergavam 406 suínos, em condições extremamente precárias. Em 300 (34,2%) casas havia o antecedente de teníase em algum membro da família. O antecedente de convulsão foi relatado por 125 (14,2%)...

  6. Determination of Cl, K, Mg, Mn, Na and V in Brazilian red wine by neutron activation analysis

    International Nuclear Information System (INIS)

    Daniele, Anna Paula; Maihara, Vera Akiko

    2015-01-01

    Several studies have been carried out for determining essential elements in foodstuffs due to important nutritional role in human body functions. Such information is crucial to any intervention in the diet of a population, thus becoming representative in the public health field. Trace elements are good indicators of wine’s origin and their concentrations can be used as criteria to ensure authenticity, quality and show that the tolerance limits established by law were respected throughout the production process. Although Brazilian wine industry is among the 15 largest in the world, analytical studies on the content of organic and inorganic compounds in wine are still small compared to other major producers. This study aimed to evaluate the elemental concentration of Cl, K, Mg, Mn, Na and V in seven national red wine samples acquired in the markets of Sao Paulo city. The analytical method applied was INAA. Concentrations of the elements in wine samples showed high variation among samples. (author)

  7. Composite Cu/Fe/MgB{sub 2} superconducting wires and MgB{sub 2}/YSZ/Hastelloy coated conductors for ac and dc applications

    Energy Technology Data Exchange (ETDEWEB)

    Glowacki, B A [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge (United Kingdom); Majoros, M [Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Madingley Road, Cambridge (United Kingdom); Vickers, M [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge (United Kingdom); Eisterer, M [Atomic Institute of the Austrian Universities, A-1020 Vienna (Austria); Toenies, S [Atomic Institute of the Austrian Universities, A-1020 Vienna (Austria); Weber, H W [Atomic Institute of the Austrian Universities, A-1020 Vienna (Austria); Fukutomi, M [National Institute for Materials Science, Superconducting Materials Center, 1-2-1, Sengen, Ibaraki (Japan); Komori, K [National Institute for Materials Science, Superconducting Materials Center, 1-2-1, Sengen, Ibaraki (Japan); Togano, K [National Institute for Materials Science, Superconducting Materials Center, 1-2-1, Sengen, Ibaraki (Japan)

    2003-02-01

    We discuss the results of a study of MgB{sub 2} multifilamentary conductors and coated conductors from the point of view of their future dc and ac applications. The correlation between the slope of the irreversibility line induced by neutron irradiation defects and in situ structural imperfections and the critical temperature and critical current density is discussed with respect to the conductor performance and applicability. We debate the possible origin of the observed anomalous decrease of ac susceptibility at 50 K in copper clad in situ powder-in-tube MgB{sub 2} wires. Different conductor preparation methods and conductor architectures, and attainable critical current densities are presented. Some numerical results on critical currents, thermal stability and ac losses of future MgB{sub 2} multifilamentary and coated conductors with magnetic cladding of their filaments are also discussed.

  8. Aspectos epidemiológicos dateníase-cisticercose na área endêmica de Lagamar, MG

    Directory of Open Access Journals (Sweden)

    Mario León Silva-Vergara

    1995-12-01

    Full Text Available Um inquérito epidemiológico sobre teníase-cisticercose foi realizado em Lagamar- MG em 1992. Cadastradas 1109 casas com 3344 habitantes. O inquérito abrangeu 875 (86% famílias e foi respondido por um informante que, em 80% dos casos, foi o pai. Na cidade havia 100 chiqueiros em 100 (11,4% casas que albergavam 406 suínos, em condições extremamente precárias. Em 300 (34,2% casas havia o antecedente de teníase em algum membro da família. O antecedente de convulsão foi relatado por 125 (14,2% famílias. O início das convulsões na idade adulta foi caracterizado em 39 (3 7,8% famílias e o antecedente de doenças mentais foi relatado em 53 (6% casas. Os exames parasitológicos de fezes mostraram ovos de Taenia spp em 24 (1,3% das 1850 amostras examinadas.

  9. Enhanced J c property in nano-SiC doped thin MgB2/Fe wires by a modified in situ PIT process

    International Nuclear Information System (INIS)

    Jiang, C.H.; Nakane, T.; Hatakeyama, H.; Kumakura, H.

    2005-01-01

    A modified in situ PIT process, which included a short time pre-annealing and intermediate drawing step in the conventional in situ PIT process, was employed to fabricate thin round MgB 2 /Fe wires from MgH 2 and B powders. The pores and cracks resulted from the MgH 2 decomposition during the pre-annealing were effectively eliminated by the intermediate drawing step, which subsequently increased the core density and J c property of final heat treated wires. A higher reduction rate after the pre-annealing led to a larger enhancement in J c within this study. The reproducibility of our new process on the J c improvement in MgB 2 wires was confirmed in two series of wires doped with 5 mol% or 10 mol% nano-SiC particles separately

  10. Effect of heavy-metal insertions at Fe/MgO interfaces on electric-field-induced modification of magnetocrystalline anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, K.; Nomura, T. [Department of Physics Engineering, Mie University, Tsu, Mie 514-8507 (Japan); Pradipto, A.-M. [Department of Physics Engineering, Mie University, Tsu, Mie 514-8507 (Japan); Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Nawa, K.; Akiyama, T.; Ito, T. [Department of Physics Engineering, Mie University, Tsu, Mie 514-8507 (Japan)

    2017-05-01

    Magnetocrystalline anisotropy (MCA) at Fe/MgO interfaces with insertions of 3d (Co, Ni), 4d (Ru, Rh, Pd), and 5d (Os, Ir, Pt) elements in external electric fields was investigated from first-principles calculations. The MCA energy and the electric-field-induced MCA modification dramatically depend on the inserted elements. Large MCA modification may be achieved by heavy-metal insertions, in which the strength of spin-orbit coupling of inserted elements and the position of the Fermi level relative to d band level play key roles. - Highlights: • MCA at Fe/MgO interface dramatically depends on insertions of 3d, 4d, and 5d elements. • Large electric-field-induced MCA modification is achieved by heavy-metal insertions. • Position of Fermi level relative to d band level plays key role in determining MCA.

  11. Enhancement in the interfacial perpendicular magnetic anisotropy and the voltage-controlled magnetic anisotropy by heavy metal doping at the Fe/MgO interface

    Directory of Open Access Journals (Sweden)

    Takayuki Nozaki

    2018-02-01

    Full Text Available We investigated the influence of heavy metal doping at the Fe/MgO interface on the interfacial perpendicular magnetic anisotropy (PMA and the voltage-controlled magnetic anisotropy (VCMA in magnetic tunnel junctions prepared by sputtering-based deposition. The interfacial PMA was increased by tungsten doping and a maximum intrinsic interfacial PMA energy, Ki,0 of 2.0 mJ/m2 was obtained. Ir doping led to a large increase in the VCMA coefficient by a factor of 4.7 compared with that for the standard Fe/MgO interface. The developed technique provides an effective approach to enhancing the interfacial PMA and VCMA properties in the development of voltage-controlled spintronic devices.

  12. X-ray fluorescence spectrometry of Al, Mg, Ca, Fe, S in solid phase of magnesite technology of combustion product desulfurization

    International Nuclear Information System (INIS)

    Vymola, R.; Hora, V.; Spitzer, Z.

    1989-01-01

    Solid phase samples of magnesite technology were moulded into pellets or melted into the shape of a glass disk. MgO, CaO, Fe 2 O 3 , S, Al 2 O 3 and SiO 2 were determined in the samples by X-ray fluorescence analysis. Fluorescence intensities were measured with an SRS 200 sequential X-ray spectrometer and the measured data were evaluated using a linked-up PDP 11/04 computer. The reproducibility of MgO, CaO, Fe 2 O 3 and S determinations was very good; higher measurement accuracy was achieved for moulded samples. The specificity of determinations was checked by a comparative chemical analysis. (E.J.). 8 tabs., 5 refs

  13. 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.

  14. Structure and magnetic properties of Mg0.35Cu0.2Zn0.45Fe2O4 ferrite synthesized by co-precipitation method

    Directory of Open Access Journals (Sweden)

    Bo Yang

    2017-05-01

    Full Text Available Mg0.35Cu0.2Zn0.45Fe2O4 nanosize particles have been synthesized by chemical co-precipitation method and characterized by X-ray diffraction (XRD and vibrating sample magnetometry (VSM. The XRD patterns confirmed the single phase spinel structure of the synthesized powder. The average crystallite size of the powder varied from 14 to 55 nm by changing annealing temperature. The activation energy for crystal growth was estimated as about 18.61KJ/mol. With the annealing temperature increasing, saturation magnetization (MS was successively increased while the coercivity (HC was first increased, passed through a maximum and then declined. The sintering temperature has significant influence on bulk density, initial permeability and Curie temperature of Mg0.35Cu0.2Zn0.45Fe2O4 ferrite.

  15. Melting Behavior and Thermolysis of NaBH4−Mg(BH4)2 and NaBH4−Ca(BH4)2 Composites

    OpenAIRE

    Ley, Morten; Roedern, Elsa; Thygesen, Peter; Jensen, Torben

    2015-01-01

    The physical properties and the hydrogen release of NaBH 4 –Mg(BH 4 ) 2 and NaBH 4 −Ca(BH 4 ) 2 composites are investigated using in situ synchrotron radiation powder X-ray diffraction, thermal analysis and temperature programmed photographic analysis. The composite, x NaBH 4 –(1 − x )Mg(BH 4 ) 2 , x = 0.4 to 0.5, shows melting/frothing between 205 and 220 °C. However, the sample does not become a transparent molten phase. This behavior is similar to other alkali-alkaline earth metal borohydr...

  16. Effect of T6 treatment on the coefficient of friction of Al25Mg2Si2Cu4Fe alloy

    Science.gov (United States)

    Sondur, D. G.; Mallapur, D. G.; Udupa, K. Rajendra

    2018-04-01

    Effect of T6 treatment on the coefficient of friction of Al25Mg2Si2Cu4Fe alloy was evaluated by conducting wear test on pin on disc wear testing machine. Wear test parameters such as the load and the speed were varied by keeping one constant and varying the other respectively. It was observed that the coefficient of friction is high for as cast condition due to the brittle microstructure. After T6 heat treatment the precipitates formed such as the Chinese scripts and the Mg2Si blocks got modified that lead to improvement in the hardness and the wear resistance. This reduces the coefficient of friction.

  17. 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

  18. 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.

  19. Constituent phase diagrams of the Al-Cu-Fe-Mg-Ni-Si system and their application to the analysis of aluminium piston alloys

    Energy Technology Data Exchange (ETDEWEB)

    Belov, N.A. [Moscow Institute of Steel and Alloys, Leninsky prosp. 4, Moscow 119049 (Russian Federation); Eskin, D.G. [Netherlands Institute for Metals Research, Rotterdamseweg 137, 2628AL Delft (Netherlands)]. E-mail: deskin@nimr.nl; Avxentieva, N.N. [Moscow Institute of Steel and Alloys, Leninsky prosp. 4, Moscow 119049 (Russian Federation)

    2005-10-15

    The evaluation of phase equilibria in quinary systems that constitute the commercially important Al-Cu-Fe-Mg-Ni-Si alloying system is performed in the compositional range of casting alloys by means of metallography, electron probe microanalysis, X-ray diffractometry, differential scanning calorimetry, and by the analysis of phase equilibria in the constituent systems of lesser dimensionality. Suggested phase equilibria are illustrated by bi-, mono- and invariant solidification reactions, polythermal diagrams of solidification, distributions of phase fields in the solid state, and isothermal and polythermal sections. Phase composition of as-cast alloys is analyzed in terms of non-equilibrium solidification. It is shown that the increase in copper concentration in piston Al-Si alloys results in the decrease in the equilibrium solidus from 540 to 505 deg C. Under non-equilibrium solidification conditions, piston alloys finish solidification at {approx}505 deg C. Iron is bound in the quaternary Al{sub 8}FeMg{sub 3}Si{sub 6} phase in low-iron alloys and in the ternary Al{sub 9}FeNi and Al{sub 5}FeSi phases in high-iron alloys.

  20. Effect of MgO on compositions of the system CaO-Al2O3-Fe2O3. Solubility

    Directory of Open Access Journals (Sweden)

    Palomo, Ángel

    1986-12-01

    Full Text Available Five different compositions belonging to the equilibrium system CaO-Al2O3-Fe2O3 were dopep with a fixed quantity of MgO (6,5% wt. The compositions, which lie in different primary fields of crystallization and in different triangles of compatibility, were submitted to several thermal treatments. Each composition, which had previously been melted, originates in its solidification the aluminates and ferrites which are usual in the interstitial phase of clinker Portland, although they are in different microstructural arrangements. The effect of MgO on the generated microstructures has been shown. Also, the solubility of MgO on the aluminic and ferritic phases has been measured.CCinco composiciones diferentes pertenecientes al sistema de equilibrio CaO-Al2O3-Fe2O3 fueron dopadas con una cantidad fija de MgO (6,5%. Las cinco composiciones, que están situadas sobre diferentes campos primarios de cristalización y/o sobre diferentes triángulos de compatibilidad, fueron sometidas a varios tratamientos térmicos. Cada composición (previamente fundida origina en su solidificación los aluminatos y ferritos habituales en la fase intersticial del clinker portland, aunque ordenados en microestructuras diferentes. Se ha comprobado el efecto del MgO sobre las microestructuras generadas, así como su solubilidad en las fases alumínicas y ferríticas.

  1. Perovskites with noble metals of type Ba/sub 3/BM/sub 2/O/sub 9/; B = Mg, Fe, Co, Ni, Zn, Cd; M = Ru, Ir

    Energy Technology Data Exchange (ETDEWEB)

    Treiber, U; Kemmler-Sack, S; Ehmann, A [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1982-04-01

    The perovskites Ba/sub 3/BM/sub 2/O/sub 9/ crystallize in a hexagonal BaTiO/sub 3/ structure and could be prepared for M = Ru; B = Mg, Fe, Co, Ni, Zn, Cd and M = Ir; B = Co, Ni. According to intensity calculations on powder data of Ba/sub 3/MgRu/sub 2/O/sub 9/ and Ba/sub 3/NiIr/sub 2/O/sub 9/ (refined intensity related R' value 6.7% (Ba/sub 3/MgRu/sub 2/O/sub 9/) and 6.9% (Ba/sub 3/NiIr/sub 2/O/sub 9/)) an 1:2 order is present and both lattices contain face connected M/sub 2/O/sub 9/ double octahedra linked by another via common corners through BO/sub 6/ single octahedra. The occurrence of this typ of cationic order results for B = Mg, Co, Ni, Zn, Cd from the analysis of the vibrational spectra. For B = Mg, Zn, Cd and presumable with B = Ni the charge distribution is B/sup 2 +// 2 M/sup 5 +/; for B = Co deviation can not be excluded. On the opposite in Ba/sub 3/FeRu/sub 2/O/sub 9/ an electron delocalisation is present.

  2. Study on the effect of the metal–support (Fe-MgO and Pt-MgO) interaction in alcohol-CVD synthesis of carbon nanotubes

    International Nuclear Information System (INIS)

    Steplewska, Anna; Borowiak-Palen, Ewa

    2011-01-01

    This study presents the effect of the metal–support interaction in two systems: (1) iron particle, and (2) platinum particles, being supported on magnesium oxide (MgO) nanopowder in alcohol-CVD process for carbon nanotubes (CNTs) growth. The employment of the different metals but the same substrate (with equal molar ratio) resulted in the synthesis of single-walled CNTs (SWCNTs) or double-walled CNTs (DWCNTs), using iron and platinum, respectively. Furthermore, along with the prolongation of the process time, the decrease of the mean nanotubes diameter in case of iron-catalyzed materials was detected. Interestingly, the extention of the growth time in the synthesis using Pt/MgO resulted in the synthesis of the thicker mean nanotubes diameter. However, for both applied catalytic systems the reduction of the diameter distribution of the tubes and the increase of relative purity of the samples upon the growth time increase were detected.

  3. Study on the effect of the metal-support (Fe-MgO and Pt-MgO) interaction in alcohol-CVD synthesis of carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Steplewska, Anna, E-mail: asteplewska@zut.edu.pl; Borowiak-Palen, Ewa [West Pomeranian University of Technology, Centre of Knowledge Based Nanomaterials and Technologies, Institute of Chemical and Environment Engineering (Poland)

    2011-05-15

    This study presents the effect of the metal-support interaction in two systems: (1) iron particle, and (2) platinum particles, being supported on magnesium oxide (MgO) nanopowder in alcohol-CVD process for carbon nanotubes (CNTs) growth. The employment of the different metals but the same substrate (with equal molar ratio) resulted in the synthesis of single-walled CNTs (SWCNTs) or double-walled CNTs (DWCNTs), using iron and platinum, respectively. Furthermore, along with the prolongation of the process time, the decrease of the mean nanotubes diameter in case of iron-catalyzed materials was detected. Interestingly, the extention of the growth time in the synthesis using Pt/MgO resulted in the synthesis of the thicker mean nanotubes diameter. However, for both applied catalytic systems the reduction of the diameter distribution of the tubes and the increase of relative purity of the samples upon the growth time increase were detected.

  4. 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...

  5. 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.

  6. Investigation of ultrasonic wave influence on magnetic alignment in layered structure 20x[Fe(20 Angstroem)/Cr(12 Angstroem)]/MgO

    International Nuclear Information System (INIS)

    Aksenov, V.L.; Nikitenko, Yu.V.; Proglyado, V.V.; Khajdukov, Yu.N.; Gavrilov, V.N.; Raitman, E.; Bottyan, L.; Nagy, D.L.

    2007-01-01

    The layered structure 20x[Fe(20 Angstroem)/Cr(12 Angstroem)]/MgO, excited by ultrasonic wave, was investigated using polarized neutron reflectometry. Magnetic domains vibrations and reduction of their effective size in magnetic field of small strength were observed. In the magnetic field close to saturation the magnetic lattice is formed in the layered structure. Interplane distance of the lattice changes with increase of the magnetic field strength as well as with ultrasonic excitation of the structure

  7. 3D CNT macrostructure synthesis catalyzed by MgFe2O4 nanoparticles-A study of surface area and spinel inversion influence

    Science.gov (United States)

    Zampiva, Rúbia Young Sun; Kaufmann Junior, Claudir Gabriel; Pinto, Juliano Schorne; Panta, Priscila Chaves; Alves, Annelise Kopp; Bergmann, Carlos Pérez

    2017-11-01

    The MgFe2O4 spinel exhibits remarkable magnetic properties that open up numerous applications in biomedicine, the environment and catalysis. MgFe2O4 nanoparticles are excellent catalyst for carbon nanotube (CNT) production. In this work, we proposed to use MgFe2O4 nanopowder as a catalyst in the production of 3D macroscopic structures based on CNTs. The creation of these nanoengineered 3D architectures remains one of the most important challenges in nanotechnology. These systems have high potential as supercapacitors, catalytic electrodes, artificial muscles and in environmental applications. 3D macrostructures are formed due to an elevated density of CNTs. The quantity and quality of the CNTs are directly related to the catalyst properties. A heat treatment study was performed to produce the most effective catalyst. Factors such as superficial area, spinel inversion, crystallite size, degree of agglomeration and its correlation with van der Waals forces were examined. As result, the ideal catalyst properties for CNT production were determined and high-density 3D CNT macrostructures were produced successfully.

  8. 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

  9. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-10-15

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

  11. Investigating the astrophysical 22Ne(p, γ23Na and 22Mg(p, γ23Al reactions with a multi-channel scattering formalism

    Directory of Open Access Journals (Sweden)

    Fraser P. R.

    2014-03-01

    Full Text Available The reaction 22Ne(p, γ23Na is key to the NeNa cycle of stellar nucleogenesis, and better understanding of the 22Mg(p, γ23Al reaction is needed to understand the 22Na puzzle in ONe white dwarf novae. We aim to study these reactions using a multi-channel algebraic scattering (MCAS formalism for low-energy nucleon-nucleus scattering, recently expanded to investigate radiative capture. As a first step towards this goal, we here calculate the energy levels of the mass-23 (Ne, Mg, Na, Al nuclei. This is not only because the resonant structure of these nuclei are related to the astrophysical -rates of interest, but also because the interaction parameters determined for describing the energy levels are an integral part of the future calculation of the astrophysical reactions when using the MCAS scheme.

  12. Biocompatibility and intradiscal application of a thermoreversible celecoxib-loaded poly-N-isopropylacrylamide MgFe-layered double hydroxide hydrogel in a canine model.

    Science.gov (United States)

    Willems, Nicole; Yang, Hsiao-Yin; Langelaan, Marloes L P; Tellegen, Anna R; Grinwis, Guy C M; Kranenburg, Hendrik-Jan C; Riemers, Frank M; Plomp, Saskia G M; Craenmehr, Eric G M; Dhert, Wouter J A; Papen-Botterhuis, Nicole E; Meij, Björn P; Creemers, Laura B; Tryfonidou, Marianna A

    2015-08-20

    Chronic low back pain due to intervertebral disc (IVD) degeneration is associated with increased levels of inflammatory mediators. Current medical treatment consists of oral anti-inflammatory drugs to alleviate pain. In this study, the efficacy and safety of a novel thermoreversible poly-N-isopropylacrylamide MgFe-layered double hydroxide (pNIPAAM MgFe-LDH) hydrogel was evaluated for intradiscal controlled delivery of the selective cyclooxygenase (COX) 2 inhibitor and anti-inflammatory drug celecoxib (CXB). Degradation, release behavior, and the ability of a CXB-loaded pNIPAAM MgFe-LDH hydrogel to suppress prostaglandin E2 (PGE2) levels in a controlled manner in the presence of a proinflammatory stimulus (TNF-α) were evaluated in vitro. Biocompatibility was evaluated histologically after subcutaneous injection in mice. Safety of intradiscal application of the loaded and unloaded hydrogels was studied in a canine model of spontaneous mild IVD degeneration by histological, biomolecular, and biochemical evaluation. After the hydrogel was shown to be biocompatible and safe, an in vivo dose-response study was performed in order to determine safety and efficacy of the pNIPAAM MgFe-LDH hydrogel for intradiscal controlled delivery of CXB. CXB release correlated to hydrogel degradation in vitro. Furthermore, controlled release from CXB-loaded hydrogels was demonstrated to suppress PGE2 levels in the presence of TNF-α. The hydrogel was shown to exhibit a good biocompatibility upon subcutaneous injection in mice. Upon intradiscal injection in a canine model, the hydrogel exhibited excellent biocompatibility based on histological evaluation of the treated IVDs. Gene expression and biochemical analyses supported the finding that no substantial negative effects of the hydrogel were observed. Safety of application was further confirmed by the absence of clinical symptoms, IVD herniation or progression of degeneration. Controlled release of CXB resulted in a nonsignificant

  13. 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.

  14. Oxygen isotope fractionation effects in soil water via interaction with cations (Mg, Ca, K, Na) adsorbed to phyllosilicate clay minerals

    Science.gov (United States)

    Oerter, Erik; Finstad, Kari; Schaefer, Justin; Goldsmith, Gregory R.; Dawson, Todd; Amundson, Ronald

    2014-07-01

    In isotope-enabled hydrology, soil and vadose zone sediments have been generally considered to be isotopically inert with respect to the water they host. This is inconsistent with knowledge that clay particles possessing an electronegative surface charge and resulting cation exchange capacity (CEC) interact with a wide range of solutes which, in the absence of clays, have been shown to exhibit δ18O isotope effects that vary in relation to the ionic strength of the solutions. To investigate the isotope effects caused by high CEC clays in mineral-water systems, we created a series of monominerallic-water mixtures at gravimetric water contents ranging from 5% to 32%, consisting of pure deionized water of known isotopic composition with homoionic (Mg, Ca, Na, K) montmorillonite. Similar mixtures were also created with quartz to determine the isotope effect of non-, or very minimally-, charged mineral surfaces. The δ18O value of the water in these monominerallic soil analogs was then measured by isotope ratio mass spectrometry (IRMS) after direct headspace CO2 equilibration. Mg- and Ca-exchanged homoionic montmorillonite depleted measured δ18O values up to 1.55‰ relative to pure water at 5% water content, declining to 0.49‰ depletion at 30% water content. K-montmorillonite enriched measured δ18O values up to 0.86‰ at 5% water content, declining to 0.11‰ enrichment at 30% water. Na-montmorillonite produces no measureable isotope effect. The isotope effects observed in these experiments may be present in natural, high-clay soils and sediments. These findings have relevance to the interpretation of results of direct CO2-water equilibration approaches to the measurement of the δ18O value of soil water. The adsorbed cation isotope effect may bear consideration in studies of pedogenic carbonate, plant-soil water use and soil-atmosphere interaction. Finally, the observed isotope effects may prove useful as molecular scale probes of the nature of mineral

  15. Increased frequency and severity of developmental deformities in rough-skinned newt (Taricha granulosa) embryos exposed to road deicing salts (NaCl and MgCl2)

    International Nuclear Information System (INIS)

    Hopkins, Gareth R.; French, Susannah S.; Brodie, Edmund D.

    2013-01-01

    Road-side aquatic ecosystems in North America are annually polluted with millions of tons of road deicing salts, which threaten the survival of amphibians which live and breed in these habitats. While much is known of the effects of NaCl, little is known of the second most-commonly used deicer, MgCl 2 , which is now used exclusively in parts of the continent. Here we report that environmentally relevant concentrations of both NaCl and MgCl 2 cause increased incidence of developmental deformities in rough-skinned newt hatchlings that developed embryonically in these salts. In addition, we provide some of the first quantification of severity of different deformities, and reveal that increased salt concentrations increase both deformity frequency and severity. Our work contributes to the growing body of literature that suggests salamanders and newts are particularly vulnerable to salt, and that the emerging pollutant, MgCl 2 is comparable in its effects to the more traditionally-used NaCl. - Highlights: ► Rough-skinned newt embryos were raised in NaCl and MgCl 2 road deicing salts. ► We quantified the frequency and severity of resulting developmental deformities. ► Both salts caused increased frequency and severity of developmental deformities. ► Effects of MgCl 2 , an emerging stressor, are comparable to traditionally-used NaCl. ► Newts and salamanders may be more susceptible to road salt than frogs and toads. - Two commonly used road deicing salts, NaCl and MgCl 2 , caused increased frequency and severity of developmental deformities in rough-skinned newt embryos.

  16. Resistência ao cisalhamento e grau de intemperismo de cinco solos na região de Lavras (MG

    Directory of Open Access Journals (Sweden)

    W. W. Rocha

    2002-06-01

    Full Text Available Atualmente os parâmetros da resistência ao cisalhamento dos solos podem ser uma ferramenta muito útil na estabilização de taludes e recuperação de voçorocas, bem como na adoção de práticas mecânicas de conservação para os solos agrícolas. Com o objetivo de avaliar a resistência ao cisalhamento de cinco solos da região de Lavras (MG e sua relação com o grau de intemperismo, realizou-se um experimento, utilizando uma prensa de cisalhamento direto, a qual permite ensaiar amostras indeformadas de solos. Essas amostras foram coletadas na profundidade de 0-0,03 m e submetidas ao ensaio de cisalhamento, para a definição das envoltórias de resistência e obtenção da coesão aparente (C e o ângulo de atrito interno (φ. Observou-se que C, de forma geral, foi maior para solos que apresentaram maior densidade, umidade a -0,01 MPa e maior teor de areia. Os valores de (φ foram maiores nos solos com maiores teores de argila. O Latossolo Vermelho-Amarelo distrófico (LVAd e o Argissolo Vermelho-Amarelo distrófico típico (PVAd, com densidades do solo, teores de areia e umidade a -0,01MPa maiores, apresentaram maiores resistências ao cisalhamento em relação ao Latossolo Vermelho distrófico (LVd, Cambissolo Háplico Tb distrófico (CXbd e Latossolo Vermelho distroférrico (LVdf, que apresentaram maiores teores de argila e matéria orgânica. Para a classe dos Latossolos, a resistência ao cisalhamento foi maior onde os índices Ki e Kr foram mais elevados, graças à estrutura em blocos apresentada pelo LVAd, que condicionou maior resistência ao cisalhamento. Do ponto de vista da resistência ao cisalhamento, os solos LVAd e PVAd mostraram-se mais resistentes a voçorocamento e ao preparo do solo.

  17. 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)

  18. Standardization of 201Tl and 55Fe radionuclides in a 4 (PC)-NaI(Tl) coincidence system

    International Nuclear Information System (INIS)

    Pires, Carlos Augusto

    2008-01-01

    In the present work the procedure for the standardization of radionuclides using the 4π(PC)-NaI(Tl) coincidence system was developed. The radionuclides selected were 201 Tl, used in nuclear medicine, and 55 Fe primary standard source, used for x-ray spectrometers calibration. The 4π(PC)-NaI(Tl) is composed of a 4 proportional counter operated at 0.1MPa coupled to two NaI(Tl) crystals. The 201 Tl decays by electron capture process followed by a prompt gamma-ray. The disintegration rate was determined by extrapolation technique using two methods: electronic discrimination and external absorbers. The radioactive sources were prepared in a 20 μg cm -2 thick Collodion film. The conventional electronic system was used. The observed events were registered by the TAC method. The 55 Fe decays by electron capture process to the ground state of 55 Mn, emitting x rays with around 6 keV. The standardization was obtained by the tracing method. This technique was applied using two radionuclides, which decay by electron capture process followed by a prompt gamma-ray, namely 51 Cr and 54 Mn, as tracers. Measurements with 1 and 2 aluminum foils, each 150 g cm-2 thick were carried out. The activity was obtained by extrapolation for zero thickness Al foil. The uncertainties were treated by means of matrix covariance methodology and takes into account all correlations involved. (author)

  19. Oxygen redox chemistry without excess alkali-metal ions in Na2/3[Mg0.28Mn0.72]O2.

    Science.gov (United States)

    Maitra, Urmimala; House, Robert A; Somerville, James W; Tapia-Ruiz, Nuria; Lozano, Juan G; Guerrini, Niccoló; Hao, Rong; Luo, Kun; Jin, Liyu; Pérez-Osorio, Miguel A; Massel, Felix; Pickup, David M; Ramos, Silvia; Lu, Xingye; McNally, Daniel E; Chadwick, Alan V; Giustino, Feliciano; Schmitt, Thorsten; Duda, Laurent C; Roberts, Matthew R; Bruce, Peter G

    2018-03-01

    The search for improved energy-storage materials has revealed Li- and Na-rich intercalation compounds as promising high-capacity cathodes. They exhibit capacities in excess of what would be expected from alkali-ion removal/reinsertion and charge compensation by transition-metal (TM) ions. The additional capacity is provided through charge compensation by oxygen redox chemistry and some oxygen loss. It has been reported previously that oxygen redox occurs in O 2p orbitals that interact with alkali ions in the TM and alkali-ion layers (that is, oxygen redox occurs in compounds containing Li + -O(2p)-Li + interactions). Na 2/3 [Mg 0.28 Mn 0.72 ]O 2 exhibits an excess capacity and here we show that this is caused by oxygen redox, even though Mg 2+ resides in the TM layers rather than alkali-metal (AM) ions, which demonstrates that excess AM ions are not required to activate oxygen redox. We also show that, unlike the alkali-rich compounds, Na 2/3 [Mg 0.28 Mn 0.72 ]O 2 does not lose oxygen. The extraction of alkali ions from the alkali and TM layers in the alkali-rich compounds results in severely underbonded oxygen, which promotes oxygen loss, whereas Mg 2+ remains in Na 2/3 [Mg 0.28 Mn 0.72 ]O 2 , which stabilizes oxygen.

  20. Polar and Magnetic Layered A Site and Rock Salt B Site-Ordered NaLnFeWO6 (Ln = La, Nd) Perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Tetuerto, Maria [State University of New Jersey, The; Li, Mang-Rong [State University of New Jersey, The; Ignatov, Alexander [State University of New Jersey, The; Croft, Mark [State University of New Jersey, The; Ramanujachary, Kandalam V. [Rowan University; Chi, Songxue [ORNL; Hodges, Jason P [ORNL; Dachraoui, W. [University of Antwerp; Hadermann, Joke [University of Antwerp; Thao Tran, T. [University of Houston, Houston; Shiv Halasyamani, P. [University of Houston, Houston; Grams, C. [Universitat zu Koln, Koln, Germany; Hemberger, J. [Universitat zu Koln, Koln, Germany; Greenblatt, M. [State University of New Jersey, The

    2013-01-01

    We have expanded the double perovskite family of materials with the unusual combination of layered order in the A sublattice and rock salt order over the B sublattice to compounds NaLaFeWO6 and NaNdFeWO6. The materials have been synthesized and studied by powder X-ray diffraction, neutron diffraction, electron diffraction, magnetic measurements, X-ray absorption spectroscopy, dielectric measurements, and second harmonic generation. At room temperature, the crystal structures of both compounds can be defined in the noncentrosymmetric monoclinic P21 space group resulting from the combination of ordering both in the A and B sublattices, the distortion of the cell due to tilting of the octahedra, and the displacement of certain cations. The magnetic studies show that both compounds are ordered antiferromagnetically below TN 25 K for NaLaFeWO6 and at 21 K for NaNdFeWO6. The magnetic structure of NaNdFeWO6 has been solved with a propagation vector k = (1/2 0 1/2) as an antiferromagnetic arrangement of Fe and Nd moments. Although the samples are potential multiferroics, the dielectric measurements do not show a ferroelectric response.

  1. A CORRELATIONAL STUDY BETWEEN CHANGES IN SERUM ELECTROLYTES (NA, K, CL, MG AND ACUTE MYOCARDIAL INFARCTION COMPLICATION

    Directory of Open Access Journals (Sweden)

    Ketan Bharatbhai Parmar

    2017-08-01

    Full Text Available BACKGROUND The term "arrhythmia" refers to any change from the normal sequence of electrical impulses. The electrical impulses may happen too fast, too slowly or erratically causing the heart to beat too fast, too slowly or erratically. When the heart doesn't beat properly, it can't pump blood effectively. When the heart doesn't pump blood effectively, the lungs, brain and all other organs can't work properly and may shutdown or be damaged. Normally, the heart's most rapidly firing cells are in the sinus (or sino-atrial or SA node making that area a natural pacemaker. Under some conditions, almost all heart tissue can start an impulse of the type that can generate a heartbeat. Cells in the heart's conduction system can fire automatically and start electrical activity. This activity can interrupt the normal order of the heart's pumping activity. Secondary pacemakers elsewhere in the heart provide a "backup" rhythm when the sinus node doesn't work properly or when impulses are blocked somewhere in the conduction system. An arrhythmia occurs when the heart's natural pacemaker develops an abnormal rate or rhythm. The normal conduction pathway is interrupted. Another part of the heart takes over as pacemaker. The aim of the study is to observe the prevalence of various electrolyte (Na, K, Cl and Mg imbalances in complications of arrhythmias. MATERIALS AND METHODS This is a prospective study in which the patient admitted with signs and symptoms of cardiac arrhythmias diagnosed clinically, 100 cases were selected over 1 year. RESULTS The serum magnesium, sodium and potassium levels were significantly lower in the AMI patients at baseline and gradually becomes near normal on 4th day. K and Mg are showing significant difference between pre and post values in males and Mg show significant difference between pre and post values day 1 and day 5 in females with arrhythmia. CONCLUSION Persistent hyponatraemia is indication of worsening cardiac failure and

  2. Crystal structure of the high-affinity Na+,K+-ATPase–ouabain complex with Mg2+ bound in the cation binding site

    DEFF Research Database (Denmark)

    Laursen, Mette; Yatime, Laure; Nissen, Poul

    2013-01-01

    of ouabain and the side chains of αM1, αM2, and αM6. Furthermore, the structure reveals that cation transport site II is occupied by Mg2+, and crystallographic studies indicate that Rb+ and Mn2+, but not Na+, bind to this site. Comparison with the low-affinity [K2]E2–MgFx–ouabain structure [Ogawa et al...

  3. Phase Behavior of Aqueous NA-K-MG-CA-CI-NO3 Mixtures: Isopiestic Measurements and Thermodynamic Modeling

    Energy Technology Data Exchange (ETDEWEB)

    M.S. Gruszkiewiez; D.A. Palmer; R.D. Springer; P. Wang; A. Anderko

    2006-09-14

    A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing the Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cl{sup -}, and NO{sub 3}{sup -} ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 C and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 C. The measurements have been performed using Oak Ridge National Laboratory's (ORNL) previously designed gravimetric isopiestic apparatus, which makes it possible to detect solid phase precipitation. Water activities are reported for mixtures with a fixed ratio of salts as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence of solid-liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data for binary, ternary and higher-order subsystems. Because of its high accuracy in calculating vapor-liquid and solid-liquid equilibria, the model is suitable for studying deliquescence behavior of multicomponent salt systems.

  4. Characterization of Anthraquinone-DerivedRedox Switchable Ionophores and Their Complexes with Li+, Na+, K+, Ca+, and Mg+ Metal Ions

    Directory of Open Access Journals (Sweden)

    Vaishali Vyas

    2011-01-01

    Full Text Available Anthraquinone derived redox switchable ionophores 1,5 bis (2-(2-(2-ethoxy ethoxy ethoxyanthracene-9,10-dione (V1 and 1,8-bis(2-(2-(2-ethoxyethoxyethoxy anthracene—9,10-dione (V2 have been used for isolation, extraction and liquid membrane transport studies of Li+, Na+, K+, Ca2+ and Mg2+ metal ions. These isolated complexes were characterized by melting point determination, CV and IR, 1H NMR spectral analysis. Ionophore V2 shows maximum shift in reduction potential (ΔE with Ca(Pic2. The observed sequence for the shifting in reduction potential (ΔE between V2 and their complexes is V2 calcium picrate (42 mV > V2 potassium picrate (33 mV > V2 lithium picrate (25 mV > V2 sodium picrate (18 mV > V2 magnesium picrate (15 mV. These findings are also supported by results of extraction, back extraction and transport studies. Ionophore V2 complexed with KPic and showed much higher extractability and selectivity towards K+ than V1. These synthetic ionophores show positive and negative cooperativity towards alkali and alkaline earth metal ions in reduced and oxidized state. Hence, this property can be used in selective separation and enrichment of metal ions using electrochemically driven ion transport.

  5. On chlorization of uranium and plutonium oxides in NaCl-KCl-MgCl2 molten eutectic

    International Nuclear Information System (INIS)

    Vorobej, M.P.; Desyatnik, V.N.; Pirogov, S.M.

    1978-01-01

    The chlorination process of U 3 O 8 , UO 2 , and PuO 2 in a melt of anhydrous NaCl-KCl-MgCl 2 with gaseous chlorine and carbon tetrachloride has been studied. The chlorination rate of uranium oxides has been studied within a temperature range 500-800 deg C at a chlorine feeding rate of 10 ml/min. Thermoqravimetric and X-ray analyses have shown that K 2 UO 2 Cl 4 compound is the final product of chlorination of uranium oxides. The mechanism of chlorination has been proposed. THe rate of PuO 2 chlorination has been studied within the same temperature range. It has been established that PuO 2 is readily chlorinated with CCl 4 vapours at a feeding rate of 10 ml/min. In contrast to uranium, chloride forms of plutonium in a highest oxidized state are unstable and are reduced in the melt to Pu(3) and Pu(4). The oxygen being released is retained by CCl 4 and by the products of CCl 4 pyrolysis

  6. 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.

  7. Particle size, spin wave and surface effects on magnetic properties of MgFe{sub 2}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Aslibeiki, B., E-mail: b.aslibeiki@tabrizu.ac.ir [Department of Physics, University of Tabriz, Tabriz 51666-16471 (Iran, Islamic Republic of); Varvaro, G.; Peddis, D. [Istituto di Struttura della Materia, National Research Council, Monterotondo Scalo, Roma 00015 (Italy); Kameli, P. [Department of Physics, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2017-01-15

    Magnesium ferrite, MgFe{sub 2}O{sub 4}, nanoparticles with a mean diameter varying from ∼6 to ∼17 nm were successfully synthesized using a simple thermal decomposition method at different annealing temperatures ranging in between 400 and 600 °C. Pure spinel ferrite nanoparticles were obtained at temperatures lower than 500 °C, while the presence of hematite (α-Fe{sub 2}O{sub 3}) impurities was observed at higher temperatures. Single-phase samples show a superparamagnetic behavior at 300 K, the saturation magnetization (M{sub s}) becoming larger with the increase of particles size. The temperature dependence of M{sub s} was explained in terms of surface spin-canting as well as spin wave excitations in the core. Using a modified Bloch law, [M{sub s}(T)=M{sub s}(0)(1−βT{sup α})], we observed a size dependent behavior of the Bloch constant β and the exponent α, whose values increase and decrease, respectively, as the particle size reduces. - Highlights: • MgFe{sub 2}O{sub 4} nanoparticles were synthesized using a thermal decomposition method. • Pure ferrite nanoparticles were obtained at temperatures lower than 500 °C. • Samples show a superparamagnetic behavior at room temperatures. • Spin wave excitations were studied using a modified Bloch law.

  8. 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

  9. Investigations of mechanical, electronic, and magnetic properties of non-magnetic MgTe and ferro-magnetic Mg0.75TM0.25Te (TM = Fe, Co, Ni): An ab-initio calculation

    International Nuclear Information System (INIS)

    Mahmood, Q; Alay-e-Abbas, S M; Mahmood, I; Noor, N A; Asif, Mahmood

    2016-01-01

    The mechanical, electronic and magnetic properties of non-magnetic MgTe and ferro-magnetic (FM) Mg 0.75 TM 0.25 Te (TM = Fe, Co, Ni) in the zinc-blende phase are studied by ab-initio calculations for the first time. We use the generalized gradient approximation functional for computing the structural stability, and mechanical properties, while the modified Becke and Johnson local (spin) density approximation (mBJLDA) is utilized for determining the electronic and magnetic properties. By comparing the energies of non-magnetic and FM calculations, we find that the compounds are stable in the FM phase, which is confirmed by their structural stabilities in terms of enthalpy of formation. Detailed descriptions of elastic properties of Mg 0.75 TM 0.25 Te alloys in the FM phase are also presented. For electronic properties, the spin-polarized electronic band structures and density of states are computed, showing that these compounds are direct bandgap materials with strong hybridizations of TM 3d states and Te p states. Further, the ferromagnetism is discussed in terms of the Zener free electron model, RKKY model and double exchange model. The charge density contours in the (110) plane are calculated to study bonding properties. The spin exchange splitting and crystal field splitting energies are also calculated. The distribution of electron spin density is employed in computing the magnetic moments appearing at the magnetic sites (Fe, Co, Ni), as well as at the non-magnetic sites (Mg, Te). It is found that the p–d hybridization causes not only magnetic moments on the magnetic sites but also induces negligibly small magnetic moments at the non-magnetic sites. (paper)

  10. Temperature Driven Topological Switch in 1T'-MoTe2 and Strain Induced Nematicity in NaFeAs

    Science.gov (United States)

    Berger, Ayelet Denise Notis

    Quasiparticle interference (QPI) is a powerful technique within Scanning Tunneling Microscopy (STM) that is used to probe the electronic bandstructure of materials. This thesis presents two examples using QPI to measure the bandstructure in materials with exotic electronic states that can be tuned via outside parameters (temperature and strain). In Part I of the thesis, we discuss the temperature dependence of Fermi Arcs in 1T'-MoTe 2, and then in Part II, the strain dependent nematic state in NaFeAs. The recent discovery of Weyl semimetals has introduced a new family of materials with topologically protected electronic properties and potential applications due to their anomalous transport effects. Even more useful is a Weyl semimetal that can be turned "on" and "off," switching between a topological and trivial state. One possible material is MoTe2, which undergoes a phase transition at 240K. This thesis consists of experiments using Scanning Tunneling Microscopy (STM) and Spectroscopy (STS) at different temperatures to visualize changes in the electronic bandstructure of MoTe2 across the topological phase transition. We show that a signature of topologically protected Fermi Arcs is present at low temperatures but disappears at room temperature, in the trivial phase. We include an in-depth discussion of how to account for thermal effects when comparing these two types of measurements. In Part II, we discuss strain induced nematicity in NaFeAs, an iron pnictide. Nematic fluctuations and spin correlations play an important role in the phase diagram of the iron pnictides, a family of unconventional superconductors. Illuminating the mechanism behind this symmetry breaking is key to understanding the superconducting state. Previous work has shown that nematicity in the iron pnictides responds strongly to applied strain [1, 2]. In this thesis, I present results from a new experimental technique, elasto-scanning tunneling microscopy (E-STM), which combines in situ strain

  11. Eldfellite, NaFe(SO4)2, a new fumarolic mineral from Eldfell volcano, Iceland

    DEFF Research Database (Denmark)

    Balic Zunic, Tonci; Garavelli, A.; Acquafredda, P.

    2009-01-01

    A new mineral, eldfellite, was found among fumarolic encrustations collected in 1990 on the Eldfell volcano, Heimaey Island, Iceland. Associated minerals are ralstonite, anhydrite, gypsum, bassanite, hematite, opal and tamarugite, as well as a presumably new mineral with the composition Na3Fe(SO4......)3. Along with opal and tamarugite, eldfellite forms soft and fragile aggregates built of thin, platy crystals of micrometre size. The mineral is yellowish-green to greenish-white, with a white streak. The calculated density is 3.062 g/cm3. Eldfellite is monoclinic, C2/m, a 8.043(4) Å, b 5.139(2) Å, c 7...

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

    Science.gov (United States)

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

    2016-02-07

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

  13. Magnetic properties of Mg{sub 12}O{sub 12} nanocage doped with transition metal atoms (Mn, Fe, Co and Ni): DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Javan, Masoud Bezi, E-mail: javan.masood@gmail.com

    2015-07-01

    Binding energy of the Mg{sub 12}O{sub 12} nanocage doped with transition metals (TM=Mn, Fe, Co and Ni) in endohedrally, exohedrally and substitutionally forms were studied using density functional theory with the generalized gradient approximation exchange-correlation functional along 6 different paths inside and outside of the Mg{sub 12}O{sub 12} nanocage. The most stable structures were determined with full geometry optimization near the minimum of the binding energy curves of all the examined paths inside and outside of the Mg{sub 12}O{sub 12} nanocage. The results reveal that for all stable structures, the Ni atom has a larger binding energy than the other TM atoms. It is also found that for all complexes additional peaks contributed by TM-3d, 4s and 4p states appear in the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) gap of the host MgO cluster. The mid-gap states are mainly due to the hybridization between TM-3d, 4s and 4p orbitals and the cage π orbitals. The magnetic moment of the endohedrally doped TM atoms in the Mg{sub 12}O{sub 12} are preserved to some extent due to the interaction between the TM and Mg{sub 12}O{sub 12} nanocage, in contrast to the completely quenched magnetic moment of the Fe and Ni atoms in the Mg{sub 11}(TM)O{sub 12} complexes. Furthermore, charge population analysis shows that charge transfer occurs from TM atom to the cage for endohedrally and substitutionally doping. - Highlights: • Binding energy of the Mg{sub 12}O{sub 12} nanocage doped with transition metals was studied. • The most stable structures were determined near the minimum of the binding energy. • The encapsulated Ni atom has a larger binding energy than the other TM atoms. • Magnetic moment of the endohedrally doped TM atoms in the Mg{sub 12}O{sub 12} are preserved.

  14. Microstructural and domain effects in epitaxial CoFe2O4 films on MgO with perpendicular magnetic anisotropy

    International Nuclear Information System (INIS)

    Comes, Ryan; Gu Man; Khokhlov, Mikhail; Lu Jiwei; Wolf, Stuart A.

    2012-01-01

    CoFe 2 O 4 (CFO) epitaxial thin films of various thicknesses were grown on MgO substrates using the pulsed electron-beam deposition technique. The films have excellent in-plane coherence with the substrate, exhibit layer-by-layer growth and have well-defined thickness fringes in x-ray diffraction measurements. Atomic force microscopy (AFM) measurements indicate that misfit dislocations form in thicker films and the critical thickness for the dislocation formation is estimated. Perpendicular magnetic anisotropy in CFO due to epitaxial in-plane tensile strain from the substrate was found. A stripe-like domain structure in the demagnetized state is demonstrated using magnetic force microscopy (MFM), in agreement with previous predictions. Coercivity increased in thicker films, which is explained by domain wall pinning due to misfit dislocations at the CFO/MgO interface. - Highlights: → X-ray diffraction and rocking curves indicate films are amongst highest quality in the literature. → Domain structure of CoFe 2 O 4 films on MgO was found to be stripe-like using MFM. → Critical thickness for misfit dislocations estimated and agrees with experiment. → Effect of misfit dislocations on surface morphology explained. → Role of dislocations and antiphase boundaries in domain wall formation and motion explained.

  15. 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

  16. Aspectos epidemiológicos dateníase-cisticercose na área endêmica de Lagamar, MG

    Directory of Open Access Journals (Sweden)

    Mario León Silva-Vergara

    1995-12-01

    Full Text Available Um inquérito epidemiológico sobre teníase-cisticercose foi realizado em Lagamar- MG em 1992. Cadastradas 1109 casas com 3344 habitantes. O inquérito abrangeu 875 (86% famílias e foi respondido por um informante que, em 80% dos casos, foi o pai. Na cidade havia 100 chiqueiros em 100 (11,4% casas que albergavam 406 suínos, em condições extremamente precárias. Em 300 (34,2% casas havia o antecedente de teníase em algum membro da família. O antecedente de convulsão foi relatado por 125 (14,2% famílias. O início das convulsões na idade adulta foi caracterizado em 39 (3 7,8% famílias e o antecedente de doenças mentais foi relatado em 53 (6% casas. Os exames parasitológicos de fezes mostraram ovos de Taenia spp em 24 (1,3% das 1850 amostras examinadas.An epidemiological inquiry of human- cysticercosis due to Taenia solium was carried out in Lagamar, Minas Gerais State, Brazil, in 1992. A survey of 1109 houses with 3344. inhabitants was made. The inquiry included 875 (86% families and the questionaire was answered by an informer, who was the father in 80% of the cases. One hmidred pigsties, sheltering 406 swines in extremely precarious conditions, were found in 100 (11.4% houses. A history on taeniasis in some member of the family was verified in 300 (34.2% houses. A histoiy of seizures was referred to by 125 (14.2% of families. The outset of convulsion in adult age was characterized in 39 (37.8% families. A history of mental disorder was reported in 53 (6.0% of houses. Stool examinations were positive for Taenia spp in 24 (1.3% of samples examined.

  17. Laponite Na+0.7[(Si8Mg5.5Li0.3)O20(OH)4]–0.7

    Indian Academy of Sciences (India)

    Si8Mg5.5Li0.3)O20(OH)4]–0.7. Negative charges are counterbalanced by Na+ ions present in the interlayer. Electrostatic screening length at pH 10 ≈30 nm. Effective maximum volume increases by a factor of 60. Thus, for less than 1 volume ...

  18. Investigation of structural, morphological and electromagnetic properties of Mg0.25Mn0.25Zn0.5-xSrxFe2O4 ferrites

    Science.gov (United States)

    Rahaman, Md. D.; Nusrat, Tania; Maleque, Rumana; Hossain, A. K. M. Akther

    2018-04-01

    Polycrystalline Mg0.25Mn0.25Zn0.5-xSrxFe2O4 (0 ≤ x ≤ 0.20) ferrites were synthesized using the solid state reaction sintering at 1373 K and 1473 K for 4 h. The XRD patterns revealed the formation of single phase cubic spinel with Sr2FeO4 and SrFe12O19 as impurity phases. The decrement in the lattice parameter for Sr2+ substituted samples is attributed to the difference in ionic radii of cations. The crystallite size decreases with increase in Sr2+ content. Low frequency dielectric dispersion is attributed due to the Maxwell-Wagner interfacial polarization. The appearance of the peak in dielectric loss spectrum for x = 0.15 and 0.20 at 1373 K and x = 0.20 at 1473 K suggests the presence of relaxing dipoles. The loss peak shifts towards lower frequency side with Sr2+ content at 1373 K which is due to the strengthening of dipole-dipole interactions. The complex impedance spectra clearly revealed that the both grain and grain boundary effects on the electrical properties. A complex electric modulus spectrum indicates that a non-Debye type of conductivity relaxation exists. The saturation magnetization and remanence gradually decreases with Sr2+ substitution which may be due to the existence of non-magnetic phase in the space between the magnetic particles and the substitution of Zn2+ cation in Mg0.25Mn0.25Zn0.5Fe2O4 ferrite lattice by Sr2+ content. The permeability decreases significantly while the cut-off frequency increases with the Sr2+ content at 1373 K and decreases at 1473 K, obeying the Snoek's law. The decrease in permeability with Sr2+ content is attributed due to the decrease in magnetization because non-magnetic ions weaken the inter-site exchange interaction.

  19. Neutron activation analysis of Ca, Cl, K, Mg, Mn, Na, P, and Sr contents in the crowns of human permanent teeth

    International Nuclear Information System (INIS)

    Zaichick, V.

    2009-01-01

    The effect of age and gender on chemical element contents in intact crowns of permanent teeth of 84 apparently healthy 15-55 year old women (n 38) and men (n = 46) was investigated. Mass fractions of Ca, Cl, K, Mg, Mn, Na, P, and Sr in crowns were determined by instrumental neutron activation analysis using short-lived radionuclides. Mean values (M ± SEL) for female and male combined were (on dry weight basis): 350 ± 5 g/kg, 2920± 150 mg/kg, 839 ± 80 mg/kg, 4880 ± 240 mg/kg, 3.20 ± 0.30 mg/kg, 6240 ± 140 mg/kg, 181 ± 4 g/kg, and 293 ± 24 mg/kg respectively. A statistically significant decrease of Sr (P ≤ 0.01) and increase of Na (P ≤ 0.01) content in the tooth crowns with age was found for women. Sex-related comparison did not show any differences. (author)

  20. Modified voltammetric, impedimetric and optical behavior of polymer- assisted sol-gel MgFe2O4 nanostructured thin films

    International Nuclear Information System (INIS)

    Bazhan, Z.; Ghodsi, F.E.; Mazloom, J.

    2017-01-01

    Highlights: •Electrochemical properties of spinel PEG/PVP MgFe 2 O 4 thin films prepared by spin coating technique have been investigated. •PSD analysis indicated that spectral roughness of films decreased by polymer incorporation. •Optical calculations exhibited a blue shift on optical band gap by polymer addition. •CV curves revealed that ion storage capacitance of PEG/MgFe 2 O 4 is two times higher than MgFe 2 O 4 thin films. •EIS analysis confirmed that incorporation of appropriate amount of PEG reduced the charge transfer resistance. -- Abstract: The effect of polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) on physical properties of sol-gel prepared magnesium ferrite (MF) thin films was investigated. The X-ray diffraction (XRD) results showed the formation of cubic spinel magnesium ferrite for all samples. The surface morphology of films changed and average surface roughness decreased by polymer addition. The height-height correlation function and fractal dimension were evaluated using cube counting and triangulation methods from atomic force microscopy (AFM) images. The refractive index and extinction coefficient of MF thin films decreased by adding polymer while the band gap value increased from 2.24 to 2.72 eV. The PEG addition enhanced the electrochemical performance while PVP addition didn’t have significant effect on cyclic voltammetry (CV) of magnesium ferrite thin films. The sample with highest value of PEG showed the maximum specific capacitance (68.5 mF cm −2 ) and the smallest charge transfer resistance (565 Ω) among all samples.

  1. Evolution of Microstructure in Rolled Mg-Based Alloy. Textural Aspect / Ewolucja Mikrostruktury W Walcowanym Stopie Na Bazie Mg. Aspekt Teksturowy

    Directory of Open Access Journals (Sweden)

    Drzymała P.

    2015-12-01

    Full Text Available Magnesium alloys are the lightest structural materials, which makes them particularly suitable for use in the aircraft and automotive industry. However, due to hexagonal close-packed crystal structure, resulting in insufficient number of independent slip systems, magnesium alloys exhibit poor formability at room temperature. Conventional methods of work hardening of magnesium alloys requires the temperature about 300°C, which favours simultaneously processes of thermal recovery and grain growth, but decreases beneficial microstructure strengthening effect. Thus, it is a crucial to undertake development of a technology for semi-finished magnesium alloys elements, which will ensure better mechanical properties of the final products by forming desirable microstructure. In the paper we present the development of crystallographic texture of the Mg-based alloy (Mg-AZ31 in the form of pipe extruded at 430°C and subjected to pilger rolling at relatively low temperature.

  2. PROPOSTA DE TRATAMENTO ALTERNATIVO PARA RESÍDUOS SÓLIDOS URBANOS NA CIDADE DE UBERLÂNDIA – MG

    Directory of Open Access Journals (Sweden)

    Caroline Ferreira de Morais

    2014-12-01

    Full Text Available O aterro sanitário é o principal meio de disposição final para os resíduos sólidos urbanos de Uberlândia. Alternativas, além das que estão em desenvolvimento no município, precisam ser pensadas já que o aterramento é uma opção com grandes impactos ao meio ambiente. Sendo assim, essa pesquisa tem como objetivo desenvolver uma proposta para a cidade de Uberlândia com uma nova alternativa de tratamento de resíduos sólidos urbanos que não priorize o seu aterramento e que traga maiores ganhos socioambientais. A metodologia consistiu em trabalhos de campo, levantamentos bibliográficos e referenciais, o qual baseou a elaboração da proposta com a adoção da tecnologia do Projeto Natureza Limpa, desenvolvido por uma empresa particular, localizada no município de Unaí – MG. A escolha da tecnologia teve como requisitos aquela que não priorizasse o aterramento de resíduos sólidos urbanos em seu processo. Portanto, os resultados são diminuição de emissões de gases de efeito estufa, aproveitamento do potencial energético da biomassa, retorno de matéria-prima ao mercado produtivo e ainda diminuição ou extinção de impactos ambientais decorrentes da má disposição dos resíduos. Consequentemente, os ganhos sociais se pautam na melhoria da saúde ambiental e o uso pela governança municipal de saldos creditícios positivos em benefício comum.

  3. Crystal structure of the high-affinity Na+K+-ATPase-ouabain complex with Mg2+ bound in the cation binding site.

    Science.gov (United States)

    Laursen, Mette; Yatime, Laure; Nissen, Poul; Fedosova, Natalya U

    2013-07-02

    The Na(+),K(+)-ATPase maintains electrochemical gradients for Na(+) and K(+) that are critical for animal cells. Cardiotonic steroids (CTSs), widely used in the clinic and recently assigned a role as endogenous regulators of intracellular processes, are highly specific inhibitors of the Na(+),K(+)-ATPase. Here we describe a crystal structure of the phosphorylated pig kidney Na(+),K(+)-ATPase in complex with the CTS representative ouabain, extending to 3.4 Å resolution. The structure provides key details on CTS binding, revealing an extensive hydrogen bonding network formed by the β-surface of the steroid core of ouabain and the side chains of αM1, αM2, and αM6. Furthermore, the structure reveals that cation transport site II is occupied by Mg(2+), and crystallographic studies indicate that Rb(+) and Mn(2+), but not Na(+), bind to this site. Comparison with the low-affinity [K2]E2-MgF(x)-ouabain structure [Ogawa et al. (2009) Proc Natl Acad Sci USA 106(33):13742-13747) shows that the CTS binding pocket of [Mg]E2P allows deep ouabain binding with possible long-range interactions between its polarized five-membered lactone ring and the Mg(2+). K(+) binding at the same site unwinds a turn of αM4, dragging residues Ile318-Val325 toward the cation site and thereby hindering deep ouabain binding. Thus, the structural data establish a basis for the interpretation of the biochemical evidence pointing at direct K(+)-Mg(2+) competition and explain the well-known antagonistic effect of K(+) on CTS binding.

  4. Use of multivariate statistical tool for data processing in the analysis of Cu, Cr, Fe, Pb, Mo and Mg in lubricating oil by LIBS

    International Nuclear Information System (INIS)

    Alves, Luana F.N.; Sarkis, Jorge E.S.; Bordon, Isabela C.A.C.

    2015-01-01

    Analysis of industrial lubricants is widely used for monitoring and predicting maintenance requirements in a broad range of mechanical systems. Laser induced breakdown spectroscopy has been used to evaluate the potentiality of the technique for the determination of metals in lubricating oils. Prior to quantitative analysis, the LIBS system was calibrated using standard samples containing the elements investigated (Cu, Cr, Fe, Pb, Mo and Mg). This study presents the usefulness of multivariate statistical techniques for evaluation and interpretation of large complex data sets in order to get more information about concentration of metals in oils lubricants is related to engine wear. (author)

  5. Specific features of the structure and weight loss of aliovalent-substituted oxides based on lanthanum gallate (La,Sr)(Ga,Fe,Mg)O3-y

    International Nuclear Information System (INIS)

    Ivanov, S. A.; Kaleva, G. M.; Aleksandrovskii, V. V.; Politova, E. D.; Eriksson, S.

    2006-01-01

    The structure of the (La 0.9 Sr 0.1 )(Ga 0.56 Fe 0.24 Mg 0.20 )O 2.85+y oxide is investigated using neutron powder diffraction at temperatures of 10, 295, and 1000 K. The results of the structure refinement are in good agreement with the dilatometric and thermogravimetric data and confirm the inference that the valence state of iron cations is higher than 3+ and that the lattice undergoes an additional expansion due to the oxygen loss at temperatures above 870 K