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Sample records for al fe zn

  1. Effect of Al and Fe doping in ZnO on magnetic and magneto-transport properties

    NASA Astrophysics Data System (ADS)

    Kumar, Santosh; Deepika; Tripathi, Malvika; Vaibhav, Pratyush; Kumar, Aman; Kumar, Ritesh; Choudhary, R. J.; Phase, D. M.

    2016-12-01

    The structural, magnetic and magneto-transport of undoped ZnO, Zn0.97Al0.03O, Zn0.95Fe0.05O and Zn0.92Al0.03Fe0.05O thin films grown on Si(100) substrate using pulsed laser deposition were investigated. The single phase nature of the films is confirmed by X-ray diffraction and Raman spectroscopy measurements. The possibility of Fe metal cluster in Fe doped/co-doped films is ruled out by Fe 2p core level photoelectron spectra. From O 1s core level spectra it is observed that oxygen vacancy is present in all the films. The undoped ZnO film shows magnetic ordering below ∼175 K, whereas Fe doped/codoped samples show magnetic ordering even at 300 K. The Al doped sample reveals paramagnetic behavior. The magneto-transport measurements suggest that the mobile carriers undergo exchange interaction with local magnetic moments.

  2. Zirconium doped nano-dispersed oxides of Fe, Al and Zn for destruction of warfare agents

    SciTech Connect

    Stengl, Vaclav; Houskova, Vendula; Bakardjieva, Snejana; Murafa, Nataliya; Marikova, Monika; Oplustil, Frantisek; Nemec, Tomas

    2010-11-15

    Zirconium doped nano dispersive oxides of Fe, Al and Zn were prepared by a homogeneous hydrolysis of the respective sulfate salts with urea in aqueous solutions. Synthesized metal oxide hydroxides were characterized using Brunauer-Emmett-Teller (BET) surface area and Barrett-Joiner-Halenda porosity (BJH), X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDX). These oxides were taken for an experimental evaluation of their reactivity with sulfur mustard (HD or bis(2-chloroethyl)sulfide), soman (GD or (3,3'-Dimethylbutan-2-yl)-methylphosphonofluoridate) and VX agent (S-[2-(diisopropylamino)ethyl]-O-ethyl-methylphosphonothionate). The presence of Zr{sup 4+} dopant can increase both the surface area and the surface hydroxylation of the resulting doped oxides, decreases their crystallites' sizes thereby it may contribute in enabling the substrate adsorption at the oxide surface thus it can accelerate the rate of degradation of warfare agents. Addition of Zr{sup 4+} converts the product of the reaction of ferric sulphate with urea from ferrihydrite to goethite. We found out that doped oxo-hydroxides Zr-FeO(OH) - being prepared by a homogeneous hydrolysis of ferric and zirconium oxo-sulfates mixture in aqueous solutions - exhibit a comparatively higher degradation activity towards chemical warfare agents (CWAs). Degradation of soman or VX agent on Zr-doped FeO(OH) containing ca. 8.3 wt.% of zirconium proceeded to completion within 30 min.

  3. EFFECTS OF AQUEOUS AL, CD, CU, FE(II), NI, AND ZN ON PB IMMOBILIZATION BY HYDROXYAPATITE

    EPA Science Inventory

    The effects of aqueous Al, Cd, Cu, Fe(II), Ni, or Zn on Pb immobilization by hydroxyapatite (Ca10(PO4),(OH)2) were studied. ead was removed mainly via hydroxyapatite dissolution and hydroxypyromorphite (Pb10(PO4)6(OH)2) precipitation in the presence of these metals with a Pb remo...

  4. Growth of epitaxial AlN films on (Mn,Zn)Fe 2O 4 substrates by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Ohta, J.; Fujioka, H.; Takahashi, H.; Oshima, M.

    2002-09-01

    We have grown AlN on (Mn,Zn)Fe 2O 4 substrates by pulsed laser deposition (PLD) and investigated their structural properties using high resolution X-ray diffraction (HRXRD), reflection high energy electron diffraction (RHEED), and atomic force microscopy (AFM). We have observed the transition of the RHEED pattern from sharp streaks into clear spots at the early stage of the film growth, which indicates that the growth mode of AlN changed from the two-dimensional mode to the three-dimensional mode due to the stress buildup. RHEED and XRD observations have revealed that hexagonal AlN (0 0 0 1) grows on (Mn,Zn)Fe 2O 4 (1 1 1) with the in-plane epitaxial relationship of [1 1 -2 0]AlN//[0 1 -1](Mn,Zn)Fe 2O 4. The lattice mismatch for this alignment is calculated to be 6%. The FWHM value of the AlN (0 0 0 2) X-ray rocking curve is as low as 77 arcsec, which indicates that the density of the threading screw dislocations in the AlN film is quite low.

  5. Influence cobalt on microstructural and hardness property of Al-Zn-Mg-Cu-Fe-Cr-Ni P/ M alloys

    NASA Astrophysics Data System (ADS)

    Naeem, Haider T.; Mohammad, Kahtan S.; Hussin, Kamarudin; Rahmat, Azim; Bashirom, Nurhuda

    2015-05-01

    In this study, influence cobalt additives on the microstructural and hardness properties of an Al-Zn-Mg-Cu-Fe-Cr-Ni PM alloy undergone the retrogression and re-aging treatment were carried out. Green compacts pressed at 370 MPa were then sintered at temperature 650°C in argon atmosphere for two hours. The sintered compacts subjected to a homogenizing treated at 470°C for 1.5 hours then aged at 120°C for 24 hours and retrogressed at 180°C for 30 minutes, and then re-aged at 120°C for 24 hours. Microstructural results of the Al-Zn-Mg-Cu-Fe-Cr-Ni-Co alloys introduced an intermetallics compound in the matrix of alloy, identified as the Al5Co2, Al70Co20Ni10 and Al4Ni3 phases besides to the MgZn2 and Mg2Zn11 phases which produced of the precipitation hardening during heat treatment. These compounds with precipitates provided strengthening of dispersion that led to improved Vickers's hardness and dinsifications properties of the alloy. The highest Vickers hardness of aluminum alloy containing cobalt was gotten after applying the retrogression and re-aging treatment.

  6. High damping Al-Fe-Mo-Si/Zn-Al composites produced by rapidly solidified powder metallurgy process

    SciTech Connect

    Li, P.Y.; Dai, S.L.; Chai, S.C.; Li, Y.R.

    2000-05-10

    The metallic materials commonly used in aircraft and aerospace fields, such as aluminum and titanium alloys, steels, etc., show extremely low damping capacity (usually of the order of or less than 10{sup {minus}3}). Thus, some problems related to vibration may emerge and influence the reliability, safety and life of airplanes, satellites, etc. It has been reported that almost two thirds of errors for rockets and satellites are related to vibration and noise. One effective way to solve these vibration-related problems is to adopt high damping metallic materials. Conventional high damping alloys exhibit damping capacity above 10{sup {minus}2}, however, their densities are usually great than 5 x 10{sup 3} kg m{sup {minus}3}, or their strengths are less than 200 MPa (for alloys based on dislocation damping), making them impossible to be applied to aircraft and aerospace areas. Recently, some low-density high-damping metal/metal composites based on aluminum and high damping alloys have been developed in Beijing Institute of Aeronautical Materials (BIAM) by the rapidly solidified power metallurgy process. This paper aims to report the properties of the composites based on a high temperature Al-Fe-Mo-Si alloy and a high damping Zn-Al alloy, and compare them with that of 2618-T61 alloy produced by the ingot metallurgy process.

  7. Highly Efficient Synthesis of Clean Biofuels from Biomass Using FeCuZnAlK Catalyst

    NASA Astrophysics Data System (ADS)

    Qiu, Song-bai; Xu, Yong; Ye, Tong-qi; Gong, Fei-yan; Yang, Zhi; Yamamoto, Mitsuo; Liu, Yong; Li, Quan-xin

    2011-12-01

    Highly efficient synthesis of clean biofuels using the bio-syngas obtained from biomass gasification was performed over Fe1.5Cu1Zn1Al1K0.117 catalyst. The maximum biofuel yield from the bio-syngas reaches about 1.59 kg biofuels/(kgcatal·h) with a contribution of 0.57 kg alcohols/(kgcatal·h) and 1.02 kg liquid hydrocarbons/(kgcatal·h). The alcohol products in the resulting biofuels were dominated by the C2+ alcohols (mainly C2—C6 alcohols) with a content of 73.55%-89.98%. The selectivity of the liquid hydrocarbons (C5+) in the hydrocarbon products ranges from 60.37% to 70.94%. The synthesis biofuels also possess a higher heat value of 40.53-41.49 MJ/kg. The effects of the synthesis conditions, including temperature, pressure, and gas hourly space velocity, on the biofuel synthesis were investigated in detail. The catalyst features were characterized by inductively coupled plasma and atomic emission spectroscopy, X-ray diffraction, temperature programmed reduction, and the N2 adsorption-desorption isotherms measurements. The present biofuel synthesis with a higher biofuel yield and a higher selectivity of liquid hydrocarbons and C2+ alcohols may be a potentially useful route to produce clean biofuels and chemicals from biomass.

  8. Comment on "Molecular controls on Cu and Zn isotopic fractionation in Fe-Mn crusts" by Little et al.

    NASA Astrophysics Data System (ADS)

    Manceau, Alain; Nagy, Kathryn L.

    2015-02-01

    Isotopic fractionation of metals between seawater and ferromanganese deposits in marine sediments is determined at equilibrium at least in part by the strength of the chemical bonding of the metals in the two environments. A generally accepted rule is that heavy isotopes are concentrated in constituents that form the stiffest bonds with these elements, where greater stiffness empirically corresponds to shorter and stronger bonds, as is the case for lower coordination numbers (Schauble, 2004). Correlatively, light isotopes are depleted. Fe-Mn oxides are enriched in heavy Zn isotope (66Zn) compared to seawater (at ∼ 1.0 ‰ vs. ∼ 0.5 ‰) and also in light Cu isotope (63Cu, at ∼ 0.4 ‰ vs. 0.9‰) (Albarède, 2004; Little et al., 2014a; Maréchal et al., 2000), which suggests that the two elements may be coordinated differently in the Zn- and Cu-bearing oxide phases.

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

    PubMed

    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. PMID:25642468

  10. Mg-Al and Zn-Fe layered double hydroxides used for organic species storage and controlled release.

    PubMed

    Seftel, E M; Cool, P; Lutic, D

    2013-12-01

    Layered double hydroxides (LDH) containing (Mg and Al) or (Zn and Fe) were prepared by coprecipitation at constant pH, using NaOH and urea as precipitation agents. The most pure LDH phase in the Zn/Fe system was obtained with urea and in Mg/Al system when using NaOH. The incorporation of phenyl-alanine (Phe) anions in the interlayer of the LDH was performed by direct coprecipitation, ionic exchange and structure reconstruction of the mixed oxide obtained by the calcination of the coprecipitated product at 400°C. The reconstruction method and the direct coprecipitation in a medium containing Phe in the initial mixture were less successful in terms of high yields of organic-mineral composite than the ionic exchange method. A spectacular change in sample morphology and yield in exchanged solid was noticed for the Zn3Fe sample obtained by ionic exchange for 6h with Phe solution. A delivery test in PBS of pH=7.4 showed the release of the Phe in several steps up to 25 h indicating different host-guest interactions between the Phe and the LDH matrix. This behavior makes the preparation useful to obtain late delivery drugs, by the incorporation of the anion inside the LDH layer. PMID:24094226

  11. Selective recovery of dissolved Fe, Al, Cu, and Zn in acid mine drainage based on modeling to predict precipitation pH.

    PubMed

    Park, Sang-Min; Yoo, Jong-Chan; Ji, Sang-Woo; Yang, Jung-Seok; Baek, Kitae

    2015-02-01

    Mining activities have caused serious environmental problems including acid mine drainage (AMD), the dispersion of mine tailings and dust, and extensive mine waste. In particular, AMD contaminates soil and water downstream of mines and generally contains mainly valuable metals such as Cu, Zn, and Ni as well as Fe and Al. In this study, we investigated the selective recovery of Fe, Al, Cu, Zn, and Ni from AMD. First, the speciation of Fe, Al, Cu, Zn, and Ni as a function of the equilibrium solution pH was simulated by Visual MINTEQ. Based on the simulation results, the predicted pHs for the selective precipitation of Fe, Al, Cu, and Zn/Ni were determined. And recovery yield of metals using simulation is over 99 %. Experiments using artificial AMD based on the simulation results confirmed the selective recovery of Fe, Al, Cu, and Zn/Ni, and the recovery yields of Fe/Al/Cu/Zn and Fe/Al/Cu/Ni mixtures using Na2CO3 were 99.6/86.8/71.9/77.0 % and 99.2/85.7/73.3/86.1 %, respectively. After then, the simulation results were applied to an actual AMD for the selective recovery of metals, and the recovery yields of Fe, Al, Cu, and Zn using NaOH were 97.2, 74.9, 66.9, and 89.7 %, respectively. Based on the results, it was concluded that selective recovery of dissolved metals from AMD is possible by adjusting the solution pH using NaOH or Na2CO3 as neutralizing agents. PMID:25231736

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

  13. Effects of Fe2+ and Zn2+ substitution on the structure and high-pressure stability of MgAl2O4 spinel from DFT calculations

    NASA Astrophysics Data System (ADS)

    Dutta, Rajkrishna; Mandal, Nibir

    2012-09-01

    Using density functional theory we show the effects of transition (Fe2+) and non-transition (Zn2+) divalent cationic substitutions on the following structural parameters: lattice parameters, bond lengths and polyhedral volumes under varying hydrostatic pressures. Fe2+ and Zn2+ substitutions lead to contrasting modifications of tetrahedral Mg-O bond lengths. Fe2+ (50%)increase the tetrahedral Mg-O bond lengths by 0.21%, whereas Zn2+ (50%) reduce it by 0.06%.We present the equations of state of Mg spinel with 50% Fe and Zn substitutions as a function of pressure. This study presents the decomposition pressure (PT) of spinel to periclase (MgO) and corundum (α-Al2O3) as a function of Fe and Zn concentrations (x). For pure spinel, PT=12.1 GPa. Fe2+substitution lowers PT linearly with its concentration as PT=-12.56x+12.02. But, Zn2+ increases PT non-linearly along a quadratic relation: PT=42.057x2+14.171x+12.174. We calculated the C44 elastic constant to explain the contrasting effects of Fe and Zn on the decomposition pressure of spinel phase.

  14. Theoretical investigations of the spin-Hamiltonian parameters and local structural distortion of Fe(3+): ZnAl2O4 crystals.

    PubMed

    Yang, Zi-Yuan

    2014-10-15

    The relations between the spin-Hamiltonian (SH) parameters and the structural parameters of the Fe(3+) ions in Fe(3+): ZnAl2O4 crystals have been established by means of the microscopic spin Hamiltonian theory and the superposition model (SPM). On the basis of this, the local structure distortion, the second-order zero-field splitting (ZFS) parameter D, the fourth-order ZFS parameter (a-F), and the Zeeman g-factors g factors: g//, g⊥, and Δg(=g//-g⊥) for Fe(3+) ions in Fe(3+): ZnAl2O4 crystals, for the first time taking into account the electronic magnetic interactions, i.e. the spin-spin (SS), the spin-other-orbit (SOO), and the orbit-orbit (OO) interactions, besides the well-known spin-orbit (SO) interaction, are theoretically investigated using complete diagonalization method (CDM). This investigation reveals that the local structure distortion effect plays an important role in explaining the spectroscopic properties of Fe(3+) ions in Fe(3+): ZnAl2O4 crystals. The theoretical second-order ZFS parameter D, the fourth-order ZFS parameter (a-F), and the Zeeman g-factors: g//, g⊥, and Δg of the ground state for Fe(3+) ion in Fe(3+): ZnAl2O4 crystals yield a good agreement with experiment findings by taking into account the lattice distortions: ΔR=0.0191nm and Δθ=0.076°. In conclusion, our research shows that there is a slight local structure distortion for Fe(3+) ions in Fe(3+): ZnAl2O4 crystals, but the site of Fe(3+) still retains D3d symmetry. On the other hand, it is found for Fe(3+) ions in Fe(3+): ZnAl2O4 crystals that the SO mechanism is the most important one, whereas the contributions to the SH parameters from other four mechanisms, including the SS, SOO, OO, and SO∼SS∼SOO∼OO mechanisms are not appreciable, especially for the ZFS parameter D. PMID:24835727

  15. The electric transport properties of Al-doped ZnO/BiFeO3/ITO glass heterostructure

    NASA Astrophysics Data System (ADS)

    Fan, Fei; Chen, Changle; Luo, Bingcheng; Jin, Kexin

    2011-04-01

    BiFeO3 (BFO) and 4 wt. % Al-doped ZnO (ZAO) layers were grown on indium tin oxide (ITO) glass substrate using a pulsed laser deposition (PLD) method. I-V curves of the ZAO/BFO/ITO glass structure were investigated over the temperature range from 60 to 240 K. Analysis of the leakage current demonstrates that Poole-Frenkel emission is the dominant mechanism in our sample. The relations between resistance and temperature at positive and negative bias voltages are different, and the difference arises from the ferroelectric switching in BFO and the interfacial depletion layer between the semiconducting and the ferroelectric layers. Magnetoresistance (MR) effect is observed and the negative MR is related to the electron spin-dependent scattering and the interface resistance of the heterostructure.

  16. Tululite, Ca14(Fe3+,Al)(Al,Zn,Fe3+,Si,P,Mn,Mg)15O36: a new Ca zincate-aluminate from combustion metamorphic marbles, central Jordan

    NASA Astrophysics Data System (ADS)

    Khoury, Hani N.; Sokol, Ella V.; Kokh, Svetlana N.; Seryotkin, Yurii V.; Nigmatulina, Elena N.; Goryainov, Sergei V.; Belogub, Elena V.; Clark, Ian D.

    2016-02-01

    Tululite (Ca14(Fe3+,Al)(Al,Zn,Fe3+,Si,P,Mn,Mg)15O36 (the hypothetical end-member formula Ca14{Fe3+O6}[SiO4][Zn5Al9]O26) (IMA2014-065) is a new natural Ca zincate-aluminate, identified in medium-temperature (800-850 °C) combustion metamorphic (CM) spurrite-fluorellestadite marbles from central Jordan. The type locality (Tulul Al Hammam area) is situated in the northern part of the Siwaqa complex, the largest area of the "Mottled Zone" Formation in the Dead Sea region. The marbles originated from bitumen-rich chalky marine sediments of the Maastrichtian-Paleogene Muwaqqar Chalk Marl Formation, which have low clay content (and, consequently, low Al) and high Zn, Cd, and U enrichments. The bulk CM rocks derived from the low-Al protolith have unusually high (Zn + Cd)/Al ratios ( 0.2) and, as a result, a mineralogy with negligibly small percentages of Ca aluminates having low Ca:Al molar ratios (minerals of mayenite supergroup, Ca:Al = 6:7) common to most of calcareous CM rocks in the Mottled Zone. Instead, the mineral assemblage of the Zn-rich marbles contains tululite, with high Ca:Al = 2.55 molar ratios and Zn substituting for a large portion of Al (Zn:Al = 1.1). Tululite occurs in thin clusters as irregular grains with indented outlines (20-100 μm in size), having typical open-work textures associated with rock-forming calcite, fluorellestadite, spurrite, and accessory Zn-rich periclase, lime-monteponite solid solutions, calcium uranates, and zincite. Marbles also bear brownmillerite, dorrite, fluormayenite, high-fluorine Ca aluminate, and lakargiite. Secondary phases are brucite, gel-like calcium silicate hydrates and calcium silicate aluminate hydrates, including Zn- and U-bearing and Cd-rich compounds, Si-bearing hydrated compounds after calcium uranates, and basic Cd chlorides. The empirical formula of the holotype tululite (a mean of 32 analyses) is (Ca13.29Cd0.75)Σ14.04(Al5.46Zn5.20Fe3+ 2.23Si0.95Mn3+ 1.01Mg0.78P0.41)Σ16.04O36. Tululite is cubic, space

  17. Accumulation of Al, Mn, Fe, Cu, Zn, Cd and Pb by the bryophyte Scapania undulata in three upland waters of different pH.

    PubMed

    Vincent, C D; Lawlor, A J; Tipping, E

    2001-01-01

    Measurements were made of the contents of Al, Mn, Fe, Cu, Zn, Cd and Pb in Scapania undulata in three streams (D2, D5, D11) in the English Lake District. The stream waters had average pH values of 5.35 (D2), 5.81 (D5) and 7.26 (D11), the main differences in other major chemical components being in Mg, Al, Ca and alkalinity. There was generally more metal accumulation in the older parts of the plants, but this was not significant in all cases. Extents of accumulation varied with stream pH and dissolved metal concentration. For Al, accumulation was greatest in streams D2 and D5. Mn accumulated most in D5 and Fe was without preference. Cu, Zn and Cd accumulated mostly in the plants in stream D11 and Pb accumulated more in D5 and D11. In terms of enrichment factors (amount of metal in the plants divided by stream water concentration) the sequence was Zn < Cd < Cu < Mn < Pb < Al < Fe. Laboratory experiments supported the findings of the field data, providing evidence that uptake increases with pH at constant total metal concentration. The results are interpreted qualitatively in terms of the chemical speciation of the metals in the stream water and competition between metal ions and protons at the plant-water interface. It is suggested that Al, Cu, Zn, Cd and Pb behave according to chemical complexation, whereas redox processes and/or colloidal interactions may be significant for Mn and Fe. PMID:11444010

  18. Global mapping of Al, Cu, Fe, and Zn in-use stocks and in-ground resources

    PubMed Central

    Rauch, Jason N.

    2009-01-01

    Human activity has become a significant geomorphic force in modern times, resulting in unprecedented movements of material around Earth. An essential constituent of this material movement, the major industrial metals aluminium, copper, iron, and zinc in the human-built environment are mapped globally at 1-km nominal resolution for the year 2000 and compared with the locations of present-day in-ground resources. While the maps of in-ground resources generated essentially combine available databases, the mapping methodology of in-use stocks relies on the linear regression between gross domestic product and both in-use stock estimates and the Nighttime Lights of the World dataset. As the first global maps of in-use metal stocks, they reveal that a full 25% of the world's Fe, Al, Cu, and Zn in-use deposits are concentrated in three bands: (i) the Eastern seaboard from Washington, D.C. to Boston in the United States, (ii) England, Benelux into Germany and Northern Italy, and (iii) South Korea and Japan. This pattern is consistent across all metals investigated. In contrast, the global maps of primary metal resources reveal these deposits are more evenly distributed between the developed and developing worlds, with the distribution pattern differing depending on the metal. This analysis highlights the magnitude at which in-ground metal resources have been translocated to in-use stocks, largely from highly concentrated but globally dispersed in-ground deposits to more diffuse in-use stocks located primarily in developed urban regions. PMID:19858486

  19. A Study on Cavitation Erosion and Corrosion Behavior of Al-, Zn-, Cu-, and Fe-Based Coatings Prepared by Arc Spraying

    NASA Astrophysics Data System (ADS)

    Kim, Jin-Hong; Lee, Myeong-Hoon

    2010-12-01

    Investigation to find a suitable coating material for a rudder application has been carried out in this study. Ten different coatings were prepared by arc spraying with Al-, Zn-, Cu-, and Fe-based wire feedstock. Both the cavitation erosion and marine corrosion behavior of the arc-sprayed coatings were evaluated, and compared with the conventional anti-corrosion paint. In terms of marine corrosion resistance, aluminum coating was the best among the tested coating systems while stainless steel coating showed the highest resistance against cavitation erosion. In addition, the effects of both the Si composition in Al-based coatings and the Ni composition in Cu- and Fe- based coatings were discussed in this study.

  20. Formation of mixed Al-Fe colloidal sorbent and dissolved-colloidal partitioning of Cu and Zn in the Cement Creek - Animas River Confluence, Silverton, Colorado

    USGS Publications Warehouse

    Schemel, L.E.; Kimball, B.A.; Runkel, R.L.; Cox, M.H.

    2007-01-01

    Transport and chemical transformations of dissolved and colloidal Al, Fe, Cu and Zn were studied by detailed sampling in the mixing zone downstream from the confluence of Cement Creek (pH 4.1) with the Animas River (pH 7.6). Complete mixing resulted in circumneutral pH in the downstream reach of the 1300 m study area. All four metals were transported through this mixing zone without significant losses to the streambed, and they exhibited transformations from dissolved to colloidal forms to varying degrees during the mixing process. Nearly all of the Al formed colloidal hydrous Al oxides (HAO) as pH increased (4.8-6.5), whereas colloidal hydrous Fe oxides (HFO) were supplied by Cement Creek as well as formed in the mixing zone primarily at higher pH (>6.5). The short travel time through the mixing zone (approx. 40 min) and pH limited the formation of HFO from dissolved Fe2+ supplied by Cement Creek. Although the proportions of HAO and HFO varied as the streams mixed, the colloidal sorbent typically was enriched in HAO relative to HFO by a factor of 1.5-2.1 (by mole) in the pH range where dissolved-to-colloidal partitioning of Cu and Zn was observed. Model simulations of sorption by HFO (alone) greatly underestimated the dissolved-to-colloidal partitioning of Zn. Previous studies have shown that HAO-HFO mixtures can sorb greater amounts of Zn than HFO alone, but the high Zn-to-sorbent ratio in this mixing zone could also account for greater partitioning. In contrast to Zn, comparisons with model simulations did not show that Cu sorption was greater than that for HFO alone, and also indicated that sorption was possibly less than what would be expected for a non-interactive mixture of these two sorbents. These field results for Cu, however, might be influenced by (organic) complexation or other factors in this natural system. Laboratory mixing experiments using natural source waters (upstream of the confluence) showed that the presence of HFO in the mixed sorbent

  1. Phase Equilibria Study of the ZnO-"FeO"-SiO2-Al2O3 System at Po2 10-8 atm

    NASA Astrophysics Data System (ADS)

    Liu, Hongquan; Cui, Zhixiang; Chen, Mao; Zhao, Baojun

    2016-04-01

    Phase equilibria studies on ZnO-"FeO"-SiO2-Al2O3 system have been carried out in the temperature range between 1523 K and 1573 K (1250 °C and 1300 °C) at Po2 10-8 atm. Experimental techniques applied in the present study include high temperature equilibration, quenching, and electron probe X-ray microanalysis (EPMA). The compositions of the phases present in the quenched samples were measured by EPMA and used to construct phase diagrams of the pseudo-ternary sections at fixed Al2O3 content. The experimental results show that, spinel, SiO2, and willemite are the major primary phase fields in the composition range investigated. With 2 wt pct Al2O3 content in the liquid phase, the liquidus temperature can be increased by 35 K in the spinel primary phase in comparison with Al2O3-free system. The partitioning of ZnO and Al2O3 between the spinel and liquid phases is also discussed in the paper.

  2. Ti/ZnO-MxOy composites (M = Al, Cr, Fe, Ce): synthesis, characterization and application as highly efficient photocatalysts for hexachlorobenzene degradation.

    PubMed

    Xia, Shengjie; Shao, Mengmeng; Zhou, Xiaobo; Pan, Guoxiang; Ni, Zheming

    2015-10-28

    A series of novel organic-inorganic nanoscale layered materials were synthesized by intercalating the Ti-containing Schiff base complex into the interlayer of the ZnM layered double hydroxides (LDHs, M = Al, Cr, Fe, Ce). The hybrid material was further calcined to make metal oxide composites with highly dispersed Ti elements (Ti/ZnO-MxOy). The structural characterization and photocatalytic results showed that, after intercalation and calcination, the metal oxide composites with a unique flower-like crystal morphology not only had high specific surface area, uniform pore size distribution and narrow band gap, but also showed extremely high photocatalytic performance for hexachlorobenzene (HCB) degradation. The Ti/ZnO-Cr2O3 composite with the narrowest band gap (2.40 eV) and the highest surface area (227 m(2)) showed the highest photocatalytic performance for HCB (95.5% within 240 min) among the four metal oxide composites. Particularly, it was found that composites derived from layered materials with different supramolecular structure of the host and guest showed different photocatalytic properties. In addition, based on the results from ESR, GC-MS and HPLC-MS, the type and amount of hydroxyl radicals, the decomposition intermediates and the pathway of HCB degradation photocatalyzed by Ti/ZnO-MxOy composites are also discussed in detail. PMID:26395810

  3. Enhancement of photoinduced electrical properties of Al-doped ZnO/BiFeO3 layered thin films prepared by chemical solution deposition

    NASA Astrophysics Data System (ADS)

    Katayama, Takeshi; Sakamoto, Wataru; Yuitoo, Isamu; Takeuchi, Teruaki; Hayashi, Koichiro; Yogo, Toshinobu

    2015-10-01

    Polycrystalline BiFeO3 and Al-doped ZnO/BiFeO3 bilayered thin films were prepared on Pt/TiOx/SiO2/Si substrates by chemical solution deposition. Their photoinduced electrical properties under blue light irradiation were characterized. The rapid on/off response of the photocurrent to light in unpoled BiFeO3 (BFO) and Al-doped ZnO/BiFeO3 (AZO/BFO) thin films was demonstrated. The AZO/BFO layered film exhibited an approximately triple-digit larger photocurrent in comparison with a BFO single-layer film. This is attributable to the photoexcited carrier generation effect at the interface between AZO (n-type) and BFO (p-type) films. Furthermore, in the AZO/BFO layered structure, the direction of the internal bias electric field caused by the space charge distribution in the unpoled BFO film is the same as that of the built-in electric field by forming a p-n junction of AZO and BFO layers. Photovoltaic properties were also improved by fabricating such a layered film. On the other hand, when the placement of BFO to AZO was reversed, the photoelectric current decreased to approximately one-tenth of that of the BFO single-layer film. In the BFO/AZO film, the internal electric field at the p-n junction between BFO and AZO is considered to have an orientation opposite to the self-bias field formed in the BFO film.

  4. Effects of Al2O3 and CaO/SiO2 Ratio on Phase Equilbria in the ZnO-"FeO"-Al2O3-CaO-SiO2 System in Equilibrium with Metallic Iron

    NASA Astrophysics Data System (ADS)

    Zhao, Baojun; Hayes, Peter C.; Jak, Evgueni

    2011-02-01

    The phase equilibria and liquidus temperatures in the ZnO-"FeO"-Al2O3-CaO-SiO2 system in equilibrium with metallic iron have been determined experimentally in the temperature range 1383 K to 1573 K (1150 °C to 1300 °C). The experimental conditions were selected to characterize lead blast furnace and imperial smelting furnace slags. The results are presented in a form of pseudoternary sections ZnO-"FeO"-(Al2O3 + CaO + SiO2) with fixed CaO/SiO2 and (CaO + SiO2)/Al2O3 ratios. It was found that wustite and spinel are the major primary phases in the composition range investigated. Effects of Al2O3 concentration as well as the CaO/SiO2 ratio on the primary phase field, the liquidus temperature, and the partitioning of ZnO between liquid and solid phases have been discussed for zinc-containing slags.

  5. Structural and magnetic study of Al{sup 3+} doped Ni{sub 0.75}Zn{sub 0.25}Fe{sub 2−x}Al{sub x}O{sub 4} nanoferrites

    SciTech Connect

    Wang, L.; Rai, B.K.; Mishra, S.R.

    2015-05-15

    Graphical abstract: Hyperfine field of individual sites (inset) and weighted average hyperfine field as a function of Al{sup 3+} content for Ni{sub 0.75}Zn{sub 0.25}Fe{sub 2−x}Al{sub x}O{sub 4}. - Highlights: • Grain size reduction with Al{sup 3+} substitution. • Preferred occupancy of Al{sup 3+} at B site for higher Al{sup 3+} content. • Reduction in Ms, Tc, and hyperfine field with increasing Al{sup 3+} content. • Size dependent variation in coercivity. • Changes in isomer shift due to competing effect of volume and substitution. - Abstract: Nanostructured Al{sup 3+} doped Ni{sub 0.75}Zn{sub 0.25}Fe{sub 2−x}Al{sub x}O{sub 4} (x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) ferrites were synthesized via the wet chemical method. X-ray diffraction, transmission electron microscopy, and magnetization measurements have been used to investigate the structural and magnetic properties of spinel ferrites calcined at 950 °C. With the doping of Al{sup 3+}, the particle size of Ni{sub 0.75}Zn{sub 0.25}Fe{sub 2−x}Al{sub x}O{sub 4} first increased to 47 nm at x = 0.4 and then decreased down to 37 nm at x = 1. The main two absorption bands in IR spectra were observed around 600 cm{sup −1} and 400 cm{sup −1} corresponding to stretching vibration of tetrahedral and octahedral group Fe{sup 3+}–O{sup 2−}. Saturation magnetization and hyperfine field values decreased linearly with Al{sup 3+} due to magnetic dilution and the relative strengths of Fe–O–Me (Me = Fe, Ni, Zn, and Al) superexchanges. The coercive field showed an inverse dependence on ferrite particle size with minimum value of 82 Oe for x = 0.4. A continuous drop in Curie temperature was observed with the Al{sup 3+} substitution. From the Moessbauer spectral analysis and X-ray diffraction analysis, it is deduced that Al{sup 3+} for x < 0.4 has no obvious preference for either tetrahedral or octahedral site but has a greater preference for the B site for x > 0.4. In nutshell the study presents detailed

  6. Phase Equilibria Studies in the System ZnO-``FeO''-Al2O3-CaO-SiO2 Relevant to Imperial Smelting Furnace Slags: Part I

    NASA Astrophysics Data System (ADS)

    Zhao, Baojun; Hayes, Peter C.; Jak, Evgueni

    2010-04-01

    The phase equilibria and liquidus temperatures in the system ZnO-“FeO”-Al2O3-CaO-SiO2 in equilibrium with metallic iron have been determined experimentally in the temperature range of 1423 K to 1553 K. The experimental conditions were focused on the composition range relevant to Imperial Smelting Furnace slags. The results are presented in the form of a pseudo-ternary section ZnO-“FeO”-(CaO + SiO2 + Al2O3) in which CaO/SiO2 = 0.93 and (CaO + SiO2)/Al2O3 = 7.0. It was found that wustite and spinel are the major primary phases and that zincite and melilite are also present in the composition range investigated. Wustite (Fe2+,Zn)O and spinel (Fe2+,Zn)O (A1,Fe3+)2O3 solid solutions are formed in this system, and the ZnO concentration in the spinel phase is found to be much greater than in the liquid phase.

  7. Investigations of zero-field splitting (ZFS) and local distortion parameters of Fe3+ ions doped into three oxi-spinels (ZnAl2O4, MgAl2O4, and ZnGa2O4) by theoretical analysis.

    PubMed

    Açıkgöz, Muhammed

    2011-08-01

    The local environment around the paramagnetic centers formed by the Fe(3+) ions doped into three oxi-spinel crystals (ZnAl(2)O(4), MgAl(2)O(4), and ZnGa(2)O(4)) is investigated utilizing the fourth-order perturbation formula of the axial zero-field splitting parameter D on the basis of the dominant spin-orbit coupling mechanism. In order to fix a plausible cubic space group for B-sites located by Al(3+)/Ga(3+) cations, several modeling approaches are used and the results are discussed in detail. PMID:21524935

  8. Modeling of circular piezoelectric micro ultrasonic transducer using CuAl10Ni5Fe4 on ZnO film for sonar applications

    NASA Astrophysics Data System (ADS)

    Yaacob, M. I. H.; Arshad, M. R.; Manaf, A. Abd.

    2011-03-01

    Modeling and theoretical characterization of piezoelectric micro ultrasonic transducer ( pMUT) using ZnO film sandwiched between nickel aluminum bronze (CuAl10Ni5Fe4) electrodes was reported in this paper. The transducer is targeted to be utilized in sonar applications. Analyses on the model were carried out using finite element method. Model's dimensional parameters were optimized for desired performance. Simplified technique was proposed to determine transmit and receive sensitivities of the model. As the result, micro ultrasonic transducer model with resonance frequency of 40 kHz was proposed with estimated receive and transmit sensitivities of -93 dB re 1 V/μPa and 137 dB re 1 μPa/V, respectively. Further model validations require actual device fabrication and this will be included in our future works.

  9. Synthesis and magnetic properties of hard-soft SRFe10Al2O19/NiZnFe2O4 ferrite nanocomposites.

    PubMed

    Rai, B K; Wang, L; Mishra, S R; Nguyen, V V; Liu, J P

    2014-07-01

    Pure phase exchange-coupled nanocomposites of hard-soft magnetic oxides, (hard) SrFe10Al2O19(-) (soft) Ni0.75Zn0.25Fe2O4 were prepared via autocombution method. Magnetic properties of the nanocomposites were assessed as a function of soft-phase content in the nanocomposite. A 40% increase in M(s) value was observed for nanocomposite with 30 Wt.% of the soft phase. A linear increase in M(r)/M(s) with soft-phase content indicates the presence of enhanced exchange-coupling between hard and soft phases of the nanocomposite. The highest M(r)/M(s) ratio of 0.68 was obtained for nanocomposite containing 30 Wt.% of the soft-phase. The observed reduction in coercieve field values of the nanocomposite with increase in soft-phase content is explained on the basis of competition between exchange and dipolar interaction between hard-soft and soft-soft phases of the nanocomposite. PMID:24758015

  10. The Aqueous Ca2+ System, in Comparison with Zn2+, Fe3+, and Al3+: An Ab Initio Molecular Dynamics Study

    SciTech Connect

    Bogatko, Stuart A.; Cauet, Emilie L.; Bylaska, Eric J.; Schenter, Gregory K.; Fulton, John L.; Weare, John H.

    2013-02-21

    Results of Ab Initio Molecular Dynamics (AIMD) simulations of a Ca2+ ion in an aqueous environment (64 waters, 38ps=5ps equilibration + 33ps data collection, 300K) are reported. The 1st hydration shell contains 6-7 waters with d(OH) = 0.97Å (identical to our bulk water estimate) and average tilt angle, I = 32º. The 1st maximum in the radial distribution function occurs at GCaO(r) = 2.45Å. Our results compare well with published experimental structural data from X-Ray Absorption (XAFS) and Neutron Diffraction. We also generate simulated XAFS spectra using a 1st principles MD-XAFS procedure and show quantitative agreement with experimental XAFS data from a 0.2m Ca(ClO4)2 aqueous solution. The Ca2+ 1st shell water dipole moment of 3.1D is identical to our bulk water estimate (3.1D). The structured 2nd hydration shell, composed of ~16.5 waters, has a maximum at GCaO(r) =4.6Å. The average 2nd shell dipole moment = 2.9D, is suppressed relative to bulk water values. Detailed H-bond analysis demonstrates the waters in this shell predominately coordinate 1st shell waters with a trigonally structured H-bond network. Two exchanges between the 1st hydration shell and the bulk were observed. These were consistent with a dissociative and dissociative interchange Eigen-Wilkins ligand exchange mechanism. Many transfers between the 2nd shell and bulk are detected for Ca2+ allowing an estimation of the 2nd shell mean residence time (MRT) of 4.6ps. Comparison of the Ca2+ hydration shell structure and dynamics with those of the recently reported Zn2+, Fe3+ and Al3+ cation species show that the 1st and 2nd hydration shell parameters, d(M-OI) distance, CNII, H-bond d(OI-OII) distance and %Tetrahedral structure are correlated with cation charge density, the ratio of cation charge (Z) and size (Rion). However, important exceptions are d(M-OII) and the 2nd shell Mean Residence Time (MRT). These differences are explained in terms of the 1st shell structure parameters (d(M-OI) distance

  11. Thermoelectric properties of metallic antiperovskites AXD3 (A=Ge, Sn, Pb, Al, Zn, Ga; X=N, C; D=Ca, Fe, Co)

    NASA Astrophysics Data System (ADS)

    Bilal, Muhammad; Ahmad, Iftikhar; Asadabadi, Saeid Jalali; Ahmad, Rashid; Maqbool, Muhammad

    2015-05-01

    In this paper we communicate the thermoelectric properties of carbon and nitrogen based metallic antiperovskites ANCa3 (A=Ge, Sn, Pb), BCFe3 (B=Al, Zn, Ga) and SnCD3 (D=Co and Fe) using the ab-initio calculations to explore efficient metallic thermoelectric materials. The consistency of the calculated results of SnCCo3 and SnCFe3 with the experimental results confirms the reliability of our theoretical calculations for the other investigated metallic antiperovskites. The results indicate that the thermopower of these materials can be enhanced by changing the chemical potential. The dimensionless figure of merit for the three nitrides approaches 0.96 at room temperature, which proves the usefulness of these materials in thermoelectric generators. Furthermore, the thermal conductivity is minimum at room temperature for chemical potential values between -0.25 μ(eV) and 0.25 μ(eV), and provides the maximum values of dimensionless figure of merit in this range. The striking feature of these studies is identifying a metallic compound, SnNCa3, with the highest value of Seebeck coefficient at room temperature out of all metals. The results anticipate that these materials could be efficient in thermoelectric generators; however, this needs experimental verification.[Figure not available: see fulltext.

  12. Experimental design optimization for the ICP-AES determination of Li, Na, K, Al, Fe, Mn and Zn in human serum.

    PubMed

    Bianchi, F; Maffini, M; Mangia, A; Marengo, E; Mucchino, C

    2007-01-17

    A chemometric approach based on experimental design and desirability functions was used to develop and validated a method for the determination of some metals of biological concern by a fast sequential ICP-AES. The elements considered are Al, Fe, Mn, Zn, Li, Na and K. The experimental design was used to investigate the effects of three instrumental most crucial parameters, such as sheath gas flow rate, pump speed and auxiliary gas flow rate. In order to improve the multielemental analysis speed, although a sequential instrument allows the use of a separate parameter set for each wavelength, regression models and desirability functions were applied to find the experimental conditions providing the highest global sensitivity. Validation was performed in terms of limits of detection (LOD), limits of quantitation (LOQ), linearity, precision and recovery. By using the 167.02 nm wavelength, aluminium LOD was 0.5 microg L(-1) while the highest LOD was found for K (65 microg L(-1)). A linear range of at least three orders of magnitude was statistically demonstrated for each element. Precision was evaluated by testing two concentration levels, and good results in terms of intra-day repeatability were obtained, with R.S.D. values lower than 4.1% at the lowest concentration level. Lacking a suitable certified reference material, trueness was estimated using the recovery rate on fortified samples. The validated method was then used in the quantification of the elements considered in a serum sample. PMID:17079109

  13. Intrinsic magnetic, structural and resistivity properties of ferromagnetic Mn{sub 0.5}Zn{sub 0.5}Al{sub x}Fe{sub 2−x}O{sub 4} nanoparticles

    SciTech Connect

    Haralkar, S.J.; Kadam, R.H.; More, S.S.; Shirsath, Sagar E.; Mane, M.L.; Patil, Swati; Mane, D.R.

    2013-03-15

    Highlights: ► Al{sup 3+} ion substituted Mn–Zn ferrite nanoparticles. ► Single phase cubic spinel structure changes with Al{sup 3+} substitution. ► Magnetization and coercivity decreased with increasing Al{sup 3+}. ► Resistivity increased with Al{sup 3+} substitution. - Abstract: In this work the nano-structural, magnetic and resistivity properties of Al{sup 3+} substituted Mn–Zn ferrites powders were investigated. Mn{sub 0.5}Zn{sub 0.5}Al{sub x}Fe{sub 2−x}O{sub 4} powders, where x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5 were obtained by the sol–gel auto-combustion method. X-ray diffraction data indicate that, after substitution, all the samples consisted of the main spinel phase in combination with a small amount of a foreign Al{sub 2}O{sub 3} phase. The addition of Al{sup 3+} resulted in a reduction of particle size and density of the prepared samples. Cation distribution in the present study was estimated by using X-ray diffraction data. The tetrahedral site radii initially increased with Al{sup 3+} content while the octahedral site radii decreased with the Al{sup 3+} substitution. FTIR spectra show two strong absorption bands at 529–548 cm{sup −1} and 445–452 cm{sup −1} which are the typical bands for the cubic spinel crystal structure. The magnetic properties were measured by employing a vibrating sample magnetometer. It was observed that the saturation magnetization, coercivity and anisotropy field decreased with the increase of Al{sup 3+} substitution. Introduction of Al{sup 3+} ions into the Mn–Zn ferrite increased the values of the resistivity, especially in the lower temperature range.

  14. Al-doped ZnO nanocrystals

    NASA Astrophysics Data System (ADS)

    Kadam, Pratibha; Agashe, Chitra; Mahamuni, Shailaja

    2008-11-01

    Al3+-doped ZnO nanocrystals were differently obtained by wet chemical and an electrochemical route. An increase in forbidden gap due to change in crystal size and also due to Al3+ doping in ZnO is critically analyzed. The Moss-Burstein type shift in Al3+-doped ZnO nanocrystals provides an evidence of successful Al3+ doping in ZnO nanocrystals. The possibility of varying the carrier concentration in ZnO nanocrystals is the indirect implication of the present investigations.

  15. Phase Equilibria Studies in the System ZnO-``FeO''-Al2O3-CaO-SiO2 Relevant to Imperial Smelting Furnace Slags: Part II

    NASA Astrophysics Data System (ADS)

    Zhao, Baojun; Hayes, Peter C.; Jak, Evgueni

    2010-04-01

    The phase equilibria and the liquidus temperatures in the system ZnO-“FeO”-Al2O3-CaO-SiO2 have been determined experimentally in equilibrium with metallic iron. Specifically, the effects of Al2O3 concentrations in Imperial Smelting Furnace slags are identified, and the results are presented in the form of pseudo-ternary sections ZnO-“FeO”-(Al2O3 + CaO + SiO2) in which CaO/SiO2 = 0.93 and (CaO + SiO2)/Al2O3 = 5.0 and 3.5, respectively. It was found that, in the presence of Al2O3, the spinel phase is formed, the spinel primary phase field expands, and the wustite and melilite primary phase fields are reduced in size with an increasing Al2O3 concentration. The implications of the findings to industrial practice are discussed.

  16. Effect of cobalt doping on the structural, magnetic and abnormal thermal expansion properties of NaZn13-type La(Fe1-xCox)11.4Al1.6 compounds.

    PubMed

    Zhao, Yuqiang; Huang, Rongjin; Li, Shaopeng; Wang, Wei; Jiang, Xingxing; Lin, Zheshuai; Li, Jiangtao; Li, Laifeng

    2016-07-27

    Cubic NaZn13-type La(Fe1-xCox)11.4Al1.6 compounds were synthesized and extensively explored through crystal structure and magnetization analyses. By optimizing the chemical composition, the isotropic abnormal properties of excellent zero and giant negative thermal expansion in a pure form were both found at different temperature ranges through room temperature. Moreover, the temperature regions with the remarkable abnormal thermal expansion (ATE) properties have been broadened which are controlled by the dM/dT. The present study demonstrates that the ATE behavior mainly depends on special structural and magnetic properties. These diverse properties suggest the high potential of La(Fe1-xCox)11.4Al1.6 for the development of abnormal expansion materials. PMID:27411397

  17. Doping effect on the structural properties of Cu1-x(Ni, Zn, Al and Fe)xO samples (0

    NASA Astrophysics Data System (ADS)

    Amaral, J. B.; Araujo, R. M.; Pedra, P. P.; Meneses, C. T.; Duque, J. G. S.; dos S. Rezende, M. V.

    2016-09-01

    In this work, the effect of insertion of transition metal, TM (=Ni, Zn, Al and Fe), ions in Cu1-xTMxO samples (0Zn-doped samples show a small amount of spurious phases for concentrations above x=0.05. Based on these results, a defect disorder study for using atomistic computational simulations which is based on the lattice energy minimization technique is employed to predict the location of the dopant ions in the structure. In agreement with XRD data, our computational results indicate that the trivalent (Al and Fe ions) are more favorable to be incorporated into CuO matrix than the divalent (Ni and Zn ions).

  18. Rapidly solidified NiAl and FeAl

    NASA Technical Reports Server (NTRS)

    Gaydosh, D. J.; Crimp, M. A.

    1984-01-01

    Melt spinning was used to produce rapidly solidified ribbons of the B2 intermetallics NiAl and FeAl. Both Fe-40Al and Fe-45Al possessed some bend ductility in the as spun condition. The bend ductility of Fe-40Al, Fe-45Al, and equiatomic NiAl increased with subsequent heat treatment. Heat treatment at approximately 0.85 T (sub m) resulted in significant grain growth in equiatomic FeAl and in all the NiAl compositions. Low bend ductility in both FeAl and NiAl generally coincided with intergranular failure, while increased bend ductility was characterized by increasing amounts of transgranular cleavage fracture.

  19. Zn Diffusion and α-Fe(Zn) Layer Growth During Annealing of Zn-Coated B Steel

    NASA Astrophysics Data System (ADS)

    Janik, Vit; Lan, Yongjun; Beentjes, Peter; Norman, David; Hensen, Guido; Sridhar, Seetharaman

    2016-01-01

    Direct hot press forming of Zn-coated 22MnB5 steels is impeded by micro-cracks that occur in the substrate due to the presence of Zn during the forming process. A study was therefore undertaken to quantify concentration of Zn across the α-Fe(Zn) coating and on grain boundaries in the α-Fe(Zn) layer and the underlying γ-Fe(Zn) substrate after isothermal annealing of Zn-coated 22MnB5 at 1173 K (900 °C) and to link the Zn distribution to the amount and type of micro-cracks observed in deformed samples. Finite difference model was developed to describe Zn diffusion and the growth of the α-Fe(Zn) layer. The penetration of Zn into the γ-Fe(Zn) substrate after 600 seconds annealing at 1173 K (900 °C) through bulk diffusion is estimated to be 3 μm, and the diffusion depth of Zn on the γ-Fe(Zn) grain boundaries is estimated to be 6 μm, which is significantly shorter than the maximum length (15 to 50 μm) of the micro-cracks formed in the severely stressed conditions, indicating that the Zn diffusion into the γ-Fe(Zn) from the α-Fe(Zn) during annealing is not correlated to the depth of micro-cracks. On the other hand, the maximum amount of Zn present in α-Fe(Zn) layer decreases with annealing time as the layer grows and Zn oxidizes, and the amount of Zn-enriched areas inside the α-Fe(Zn) layer is reduced leading to reduced length of cracking. Solid-Metal-Induced Embrittlement mechanism is proposed to explain the benefit of extended annealing on reduced depth of micro-crack penetration into the γ-Fe(Zn) substrate.

  20. Zn Speciation in two Fe-Mn Banded Systems

    NASA Astrophysics Data System (ADS)

    Marcus, M.; Manceau, A.; Kersten, M.; Tazaki, K.

    2002-12-01

    We have used micro-EXAFS spectroscopy to study the speciation of Zn in two shallow-water Fe-Mn banded structures. One of the samples is from the Baltic Sea and contains anthropogenic Zn in a matrix which is believed to be banded due to annual oscillations in oxygen content, pH and other variables of water chemistry (Hlawatsch, et. al., 2002). The other sample, from Akayu Hot Springs off the coast of a volcanic island (Satsuma-Iwo Jima) at the southern tip of Japan, is a hardened biomat in which the compositional oscillations are at least partly due to bacterial action, and in which the Zn content is natural (Tazaki, 2000). By using a beam as small as 5μm in diameter, we can look at details of metal distribution and speciation on a spatial scale much finer than the banding, which has wavelengths of order 100μm. In both samples, the Zn is associated with the high-Mn layers, though the layer-to-layer contrast is lower in the Japan sample. However, the speciation of Zn is different in the two samples. The Baltic sample shows Zn only in one form - sorbed on a layered phyllomanganate resembling birnessite with Zn tetrahedrally coordinated and sorbed to vacant octahedral sites of the Mn layer. This species was also found in soil (Manceau et. al., 2000). The Japan sample also has tetrahedral Zn in birnessite-like phyllomanganate as well as Zn in at least two other forms. The phyllomanganate species is thus seen to be a ubiquitous sink for Zn in the environment. We will discuss some possible reasons for the differences and similarities of Zn speciation in these two systems. Hlawatsch, S., Garbe-Schönberg, C.D., Lechtenberg, F., Manceau, A., Tamura, N., Kulik, D.A., Kersten, M. (2002) Trace metal fluxes to ferromanganese nodules from the western Baltic Sea as a record for long-term environmental changes. Chemical Geology, 182 697-709. Manceau A., Lanson B., Schlegel M.L., Hargé J.C., Musso M., Eybert-Bérard L., Hazemann J.L., Chateigner D., Lamble G.M. (2000

  1. Dopant concentration dependent growth of Fe:ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Sahai, Anshuman; Goswami, Navendu

    2016-05-01

    Systematic investigations of structural properties of 1-10% Fe doped ZnO nanostructure (Fe:ZnO NS) prepared via chemical precipitation method have been reported. Structural properties were probed thoroughly employing scanning electron microscope (SEM) and transmission electron microscope (TEM), energy dispersive X-ray (EDAX) analysis and X-ray diffraction (XRD). Morphological transformation of nanostructures (NS) with Fe incorporation is evident in SEM/TEM images. Nanoparticles (NP) obtained with 1% Fe, evolve to nanorods (NR) for 3% Fe; NR transform to nanocones (NC) (for 5% and 7% Fe) and finally NC transform to nanoflakes (NF) at 10% Fe. Morover, primary phase of Zn1-xFexO along with secondary phases of ZnFe2O4 and Fe2O3 were also revealed through XRD measurements. Based on collective XRD, SEM, TEM, and EDAX interpretations, a model for morphological evolution of NS was proposed and the pivotal role of Fe dopant was deciphered.

  2. Microstructural Evolution of the 55 Wt Pct Al-Zn Coating During Press Hardening

    NASA Astrophysics Data System (ADS)

    Lee, Chang Wook; De Cooman, Bruno Charles

    2014-09-01

    Press hardening is increasingly being used to produce ultra-high strength steel parts for passenger cars. Al-Si, Zn, and Zn-alloy coatings have been used to provide corrosion protection to press hardening steel grades. The use of coatings has drawbacks such as coating delamination or liquid metal-induced embrittlement. In the present work, the microstructural evolution of Al-Zn coating during press hardening was studied. The 55 wt pct Al-Zn coating can in principle provide both Al barrier protection and Zn cathodic protection to press hardened steel. During the heat treatment associated with the press hardening, the 55 wt pct Al-Zn alloy coating is converted to an intermetallic surface layer of Fe2Al5 and a FeAl intermetallic diffusion layer. The Zn is separated from both intermetallic compounds and accumulates at grain boundaries and at the surface. This Zn separation process is beneficial in terms of providing cathodic protection to Al-Zn coated press hardening steel.

  3. Catalytic behaviour and copper leaching of Cu0.10Zn0.90Al1.90Fe0.10O4 spinel for catalytic wet air oxidation of phenol.

    PubMed

    Xu, Aihua; Sun, Chenglin

    2012-06-01

    A Cu0.10Zn0.90Al1.90Fe0.10O4 spinel catalyst prepared by the sol-gel method was tested for catalytic wet air oxidation (CWAO) of phenol. The catalyst showed high activity for phenol degradation. During successive test at 170 degrees C, 100% phenol conversion and 95% chemical oxygen demand (COD) removal were observed. Results from scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) indicated that the catalyst structure remained unchanged during reaction. From the analysis of temperature programmed reduction (TPR), diffuse reflectance UV-Vis spectra (DR UV-Vis) and activity assay at basic solution pH, it can be suggested that the highly dispersed copper ions on the catalyst surface were almost completely dissolved into the reaction solution, whereas the tetra-coordinated copper ions were not only stable against leaching but also active towards phenol degradation. PMID:22856307

  4. Orientation relationship of eutectoid FeAl and FeAl2

    PubMed Central

    Scherf, A.; Kauffmann, A.; Kauffmann-Weiss, S.; Scherer, T.; Li, X.; Stein, F.; Heilmaier, M.

    2016-01-01

    Fe–Al alloys in the aluminium range of 55–65 at.% exhibit a lamellar microstructure of B2-ordered FeAl and triclinic FeAl2, which is caused by a eutectoid decomposition of the high-temperature Fe5Al8 phase, the so-called ∊ phase. The orientation relationship of FeAl and FeAl2 has previously been studied by Bastin et al. [J. Cryst. Growth (1978 ▸), 43, 745] and Hirata et al. [Philos. Mag. Lett. (2008 ▸), 88, 491]. Since both results are based on different crystallographic data regarding FeAl2, the data are re-evaluated with respect to a recent re-determination of the FeAl2 phase provided by Chumak et al. [Acta Cryst. (2010 ▸), C66, i87]. It is found that both orientation relationships match subsequent to a rotation operation of 180° about a 〈112〉 crystallographic axis of FeAl or by applying the inversion symmetry of the FeAl2 crystal structure as suggested by the Chumak data set. Experimental evidence for the validity of the previously determined orientation relationships was found in as-cast fully lamellar material (random texture) as well as directionally solidified material (∼〈110〉FeAl || solidification direction) by means of orientation imaging microscopy and global texture measurements. In addition, a preferential interface between FeAl and FeAl2 was identified by means of trace analyses using cross sectioning with a focused ion beam. On the basis of these habit planes the orientation relationship between the two phases can be described by (01)FeAl || (114) and [111]FeAl || [10]. There is no evidence for twinning within FeAl lamellae or alternating orientations of FeAl lamellae. Based on the determined orientation and interface data, an atomistic model of the structure relationship of Fe5Al8, FeAl and FeAl2 in the vicinity of the eutectoid decomposition is derived. This model is analysed with respect to the strain which has to be accommodated at the interface of FeAl and FeAl2. PMID:27047304

  5. Enriching rice with Zn and Fe while minimizing Cd risk

    PubMed Central

    Slamet-Loedin, Inez H.; Johnson-Beebout, Sarah E.; Impa, Somayanda; Tsakirpaloglou, Nikolaos

    2015-01-01

    Enriching iron (Fe) and zinc (Zn) content in rice grains, while minimizing cadmium (Cd) levels, is important for human health and nutrition. Natural genetic variation in rice grain Zn enables Zn-biofortification through conventional breeding, but limited natural Fe variation has led to a need for genetic modification approaches, including over-expressing genes responsible for Fe storage, chelators, and transporters. Generally, Cd uptake and allocation is associated with divalent metal cations (including Fe and Zn) transporters, but the details of this process are still unknown in rice. In addition to genetic variation, metal uptake is sometimes limited by its bioavailability in the soil. The availability of Fe, Zn, and Cd for plant uptake varies widely depending on soil redox potential. The typical practice of flooding rice increases Fe while decreasing Zn and Cd availability. On the other hand, moderate soil drying improves Zn uptake but also increases Cd and decreases Fe uptake. Use of Zn- or Fe-containing fertilizers complements breeding efforts by providing sufficient metals for plant uptake. In addition, the timing of nitrogen fertilization has also been shown to affect metal accumulation in grains. The purpose of this mini-review is to identify knowledge gaps and prioritize strategies for improving the nutritional value and safety of rice. PMID:25814994

  6. Enriching rice with Zn and Fe while minimizing Cd risk.

    PubMed

    Slamet-Loedin, Inez H; Johnson-Beebout, Sarah E; Impa, Somayanda; Tsakirpaloglou, Nikolaos

    2015-01-01

    Enriching iron (Fe) and zinc (Zn) content in rice grains, while minimizing cadmium (Cd) levels, is important for human health and nutrition. Natural genetic variation in rice grain Zn enables Zn-biofortification through conventional breeding, but limited natural Fe variation has led to a need for genetic modification approaches, including over-expressing genes responsible for Fe storage, chelators, and transporters. Generally, Cd uptake and allocation is associated with divalent metal cations (including Fe and Zn) transporters, but the details of this process are still unknown in rice. In addition to genetic variation, metal uptake is sometimes limited by its bioavailability in the soil. The availability of Fe, Zn, and Cd for plant uptake varies widely depending on soil redox potential. The typical practice of flooding rice increases Fe while decreasing Zn and Cd availability. On the other hand, moderate soil drying improves Zn uptake but also increases Cd and decreases Fe uptake. Use of Zn- or Fe-containing fertilizers complements breeding efforts by providing sufficient metals for plant uptake. In addition, the timing of nitrogen fertilization has also been shown to affect metal accumulation in grains. The purpose of this mini-review is to identify knowledge gaps and prioritize strategies for improving the nutritional value and safety of rice. PMID:25814994

  7. Magnetic properties of spin frustrated spinel ZnFe2O4/ZnCr2O4 superlattices

    NASA Astrophysics Data System (ADS)

    Murata, T.; Kozuka, Y.; Uchida, M.; Kawasaki, M.

    2015-11-01

    Superlattice films composed of frustrated spin systems, [ZnFe2O4]m/[ZnCr2O4]m, are grown on MgAl2O4 (111) substrates by pulsed laser deposition, and their frustrated magnetism is studied. The superlattice films show spin-glass behavior and the spin-glass transition temperature (Tg) varies nonmonotonically as a function of the layer thickness m. Tg increases with decreasing m due to an increase in the inhomogeneous exchange interaction between Cr3+ and Fe3+ at the interface. However, below m = 4, a decrease in Tg is observed. Compared with the solid solution Zn(CrFe)O4 film and the other superlattices, the decrease in Tg is considered to be a unique property of the periodically modulated short period superlattices.

  8. Effects of Zn additions to highly magnetoelastic FeGa alloys

    SciTech Connect

    Lograsso, Thomas A.; Jones, Nicholas J.; Wun-Fogle, Marilyn; Restorff, James B.; Schlagel, Deborah L.; Petculescu, Gabriela; Clark, Arthur E.; Hathaway, Kristl B.

    2015-05-07

    Fe{sub 1−x}M{sub x} (M = Ga, Ge, Si, Al, Mo and x ∼ 0.18) alloys offer an extraordinary combination of magnetoelasticity and mechanical properties. They are rare-earth-free, can be processed using conventional deformation techniques, have high magnetic permeability, low hysteresis, and low magnetic saturation fields, making them attractive for device applications such as actuators and energy harvesters. Starting with Fe-Ga as a reference and using a rigid-band-filling argument, Zhang et al. predicted that lowering the Fermi level by reducing the total number of electrons could enhance magnetoelasticity. To provide a direct experimental validation for Zhang's hypothesis, elemental additions with lower-than-Ga valence are needed. Of the possible candidates, only Be and Zn have sufficient solubility. Single crystals of bcc Fe-Ga-Zn have been grown with up to 4.6 at. % Zn in a Bridgman furnace under elevated pressure (15 bars) in order to overcome the high vapor pressure of Zn and obtain homogeneous crystals. Single-crystal measurements of magnetostriction and elastic constants allow for the direct comparison of the magnetoelastic coupling constants of Fe-Ga-Zn with those of other magnetoelastic alloys in its class. The partial substitution of Ga with Zn yields values for the magnetoelastic coupling factor, −b{sub 1}, comparable to those of the binary Fe-Ga alloy.

  9. RbZnFe(PO4)2: synthesis and crystal structure

    PubMed Central

    Badri, Abdessalem; Ben Amara, Mongi

    2016-01-01

    A new iron phosphate, rubidium zinc iron(III) phosphate, RbZnFe(PO4)2, has been synthesized as single crystals by the flux method. This compound is isostructural to the previously reported KCoAl(PO4)2 [Chen et al. (1997 ▸). Acta Cryst. C53,1754–1756]. Its structure consists of a three-dimensional framework built up from corner-sharing PO4 and (Zn,Fe)O4 tetra­hedra. This mode of linkage forms channels parallel to the [100], [010] and [001] directions in which the Rb+ ions are located. PMID:27536385

  10. RbZnFe(PO4)2: synthesis and crystal structure.

    PubMed

    Badri, Abdessalem; Ben Amara, Mongi

    2016-08-01

    A new iron phosphate, rubidium zinc iron(III) phosphate, RbZnFe(PO4)2, has been synthesized as single crystals by the flux method. This compound is isostructural to the previously reported KCoAl(PO4)2 [Chen et al. (1997 ▸). Acta Cryst. C53,1754-1756]. Its structure consists of a three-dimensional framework built up from corner-sharing PO4 and (Zn,Fe)O4 tetra-hedra. This mode of linkage forms channels parallel to the [100], [010] and [001] directions in which the Rb(+) ions are located. PMID:27536385

  11. Schottky barrier effect on the electrical properties of Fe3O4/ZnO and Fe3O4/Nb : SrTiO3 heterostructures

    NASA Astrophysics Data System (ADS)

    Yang, Kiwon; Kim, D. H.; Dho, Joonghoe

    2011-09-01

    The current-voltage (I-V) characteristics of Fe3O4/Nb-doped SrTiO3(Nb : STO) and Fe3O4/ZnO junctions prepared by pulsed laser deposition were investigated as a function of temperature. The rectifying behaviour was more distinctive in Fe3O4/Nb : STO than in the Fe3O4/ZnO. Contrary to Fe3O4/Nb : STO, remarkably, the current flow in Fe3O4/ZnO was slightly larger for negative bias voltages than for positive bias voltages. The threshold voltage in Fe3O4/Nb : STO dramatically shifted to a higher voltage by decreasing the temperature, and hysteresis behaviour with a cyclic voltage sweep appeared below 120 K. Upon cooling, the rectifying behaviour in Fe3O4/ZnO gradually disappeared within the measurement range. The observed difference between Fe3O4/Nb : STO and Fe3O4/ZnO could be explained by the shape and height of the Schottky barrier which was determined by the relative magnitude of the work functions of the two contact materials. The formation of the Schottky barrier presumably resulted from an upward shift of the interface band in Fe3O4/Nb : STO, while a little downward shift of the interface band occurred in Fe3O4/ZnO. In addition, Al-doping into ZnO induced a complete disappearance of the Schottky barrier in the Fe3O4/Al-doped ZnO junction.

  12. The electrochemical behaviors of Zn-Al-La-hydrotalcite in Zn-Ni secondary cells

    NASA Astrophysics Data System (ADS)

    Fan, Xinming; Yang, Zhanhong; Xie, Xiaoe; Long, Wei; Wang, Ruijuan; Hou, Zhilin

    2013-11-01

    Zn-Al-La-CO3 layered double hydroxides (LDHs) are prepared by the constant pH co-precipitation method and proposed as a novel anodic material in Zinc-Nickel secondary cells. The X-ray diffraction (XRD) patterns and scanning electron microscopy (SEM) images reveal that the as-prepared samples are well-crystallized and hexagon layer structure. Electrochemical performances of Zn-Al-La-hydrotalcites with different Zn/Al/La molar ratios are investigated by galvanostatic charge-discharge measurements, cyclic voltammograms (CV) and Tafel polarization curves. In comparison with the Zn-Al-hydrotalcite, Zn-Al-La-hydrotalcites with different Zn/Al/La molar ratios have more stable cycling performance. After 400 cell cycles, Zn-Al-La-LDH with Zn/Al/La = 3:0.8:0.2 retains specific discharge capacity of 297 mAh g-1 with a retention rate of 79.0%, which is much superior to that of 205 mAh g-1 with a retention rate of 53.5% for the Zn-Al-La-LDH with Zn/Al/La = 3:0.9:0.1 and 241 mAh g-1 with a retention rate of 69.0% for the Zn-Al-La-LDH with Zn/Al/La = 3:0.6:0.4. The results demonstrate that the Zn-Al-La-LDH with Zn/Al/La = 3:0.8:0.2 has the best reversible cycling behavior. The CV exhibits well reversibility and the Tafel polarization curves reveal more positive corrosion potential for Zn-Al-La-hydrotalcite.

  13. Erratum to “Crystal structure and zinc location in the BaZnFe6O11 Y-type hexagonal ferrite” by Collomb et al. [J. Magn. Magn. Mater. 78(1) (1989) 77-84

    NASA Astrophysics Data System (ADS)

    Wise, Adam; Rocks, Jason; Laughlin, David; McHenry, Michael

    2012-03-01

    In the paper "Crystal structure and zinc location in the BaZnFe6O11 Y-type hexagonal ferrite" by Collomb et al. [1], the detailed list of atomic positions gives the fractional coordinate location of the Me5 atom at the 18h symmetry site as x: 0.50317, y: -0.50317, and z: 0.19073 in a hexagonal cell. We believe this to be a typographical error, and that the fractional coordinate for the z-position should be approximately z: 0.109. The Y-type hexagonal ferrite has the space group symmetry R-3m. When this symmetry is applied to the positions given in the paper, using CrystalMaker software, the center to center distance between the Me5 atoms and the O5 atoms is only 0.27 A, an unrealistic number. In the paper, the closest-approach distance between Me5 and O5 atoms is listed as 2.048 A. Since the R-3m symmetry of the system is well-documented, the issue must lie with either the oxygen or metal atom fractional coordinate.

  14. Chitosan film loaded with silver nanoparticles-sorbent for solid phase extraction of Al(III), Cd(II), Cu(II), Co(II), Fe(III), Ni(II), Pb(II) and Zn(II).

    PubMed

    Djerahov, Lubomir; Vasileva, Penka; Karadjova, Irina; Kurakalva, Rama Mohan; Aradhi, Keshav Krishna

    2016-08-20

    The present study describes the ecofriendly method for the preparation of chitosan film loaded with silver nanoparticles (CS-AgNPs) and application of this film as efficient sorbent for separation and enrichment of Al(III), Cd(II), Cu(II), Co(II), Fe(III), Ni(II), Pb(II) and Zn(II). The stable CS-AgNPs colloid was prepared by dispersing the AgNPs sol in chitosan solution at appropriate ratio and further used to obtain a cast film with very good stability under storage and good mechanical strength for easy handling in aqueous medium. The incorporation of AgNPs in the structure of CS film and interaction between the polymer matrix and nanoparticles were confirmed by UV-vis and FTIR spectroscopy. The homogeneously embedded AgNPs (average diameter 29nm, TEM analysis) were clearly observed throughout the film by SEM. The CS-AgNPs nanocomposite film shows high sorption activity toward trace metals under optimized chemical conditions. The results suggest that the CS-AgNPs nanocomposite film can be feasibly used as a novel sorbent material for solid-phase extraction of metal pollutants from surface waters. PMID:27178907

  15. Influence of hot isostatic pressing on the structure and properties of an innovative low-alloy high-strength aluminum cast alloy based on the Al-Zn-Mg-Cu-Ni-Fe system

    NASA Astrophysics Data System (ADS)

    Akopyan, T. K.; Padalko, A. G.; Belov, N. A.

    2015-11-01

    Hot isostatic pressing (HIP) is applied for treatment of castings of innovative low-ally high-strength aluminum alloy, nikalin ATs6N0.5Zh based on the Al-Zn-Mg-Cu-Ni-Fe system. The influence of HIP on the structure and properties of castings is studied by means of three regimes of barometric treatment with different temperatures of isometric holding: t 1 = 505 ± 2°C, p 1 = 100 MPa, τ1 = 3 h (HIP1); t 2 = 525 ± 2°C, p 2 = 100 MPa, τ2 = 3 h (HIP2); and t 3 = 545 ± 2°C, p 3 = 100 MPa, τ3 = 3 h (HIP3). It is established that high-temperature HIP leads to actually complete elimination of porosity and additional improvement of the morphology of second phases. Improved structure after HIP provides improvement properties, especially of plasticity. In particular, after heat treatment according of regime HIP2 + T4 (T4 is natural aging), the alloy plasticity is improved by about two times in comparison with the initial state (from ~6 to 12%). While applying regime HIP3 + T6 (T6 is artificial aging for reaching the maximum strength), the plasticity has improved by more than three times in comparison with the initial state, as after treatment according to regimes HIP1 + T6 and HIP2 + T6 (from ~1.2 to ~5.0%), which are characterized by a lower HIP temperature.

  16. Modulus measurements in ordered Co-Al, Fe-Al, and Ni-Al alloys

    NASA Technical Reports Server (NTRS)

    Harmouche, M. R.; Wolfenden, A.

    1985-01-01

    The composition and/or temperature dependence of the dynamic Young's modulus for the ordered B2 Co-Al, Fe-Al, and Ni-Al aluminides has been investigated using the piezoelectric ultrasonic composite oscillator technique (PUCOT). The modulus has been measured in the composition interval 48.49 to 52.58 at. pct Co, 50.87 to 60.2 at. pct Fe, and 49.22 to 55.95 at. pct Ni for Co-Al, Fe-Al, and Ni-Al, respectively. The measured values for Co-Al are in the temperature interval 300 to 1300 K, while those for the other systems are for ambient temperature only. The data points show that Co-Al is stiffer than Fe-Al, which is stiffer than Ni-Al. The data points for Fe-Al and Ni-Al are slightly higher than those reported in the literature.

  17. Uptake of Al, As, Cr, Cd, Cu, Fe, Mn, Ni, Pb, Sr, and Zn in native wheatgrasses, wildryes, and bluegrass on three metal-contaminated soils from Montana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    One of the biggest challenges to successfully phytoremediate contaminated mineland soils is the identification of native plants that possess a broad adaptation to ecological sites and either exclude or uptake heavy metals of interest. This study evaluated forage concentrations of aluminum (Al), ars...

  18. Fe:ZnSe and Fe:ZnMgSe lasers pumped by Er:YSGG radiation

    NASA Astrophysics Data System (ADS)

    Jelínková, H.; Doroshenko, M. E.; Jelínek, M.; Å ulc, J.; Němec, M.; Kubeček, V.; Zagoruiko, Y. A.; Kovalenko, N. O.; Gerasimenko, A. S.; Puzikov, V. M.; Komar, V. K.

    2015-02-01

    The aim of the presented work was to design and characterize bulk Fe:ZnSe and Fe:Zn(1-x)Mg(x)Se (Mg content x = 0.19) lasers coherently pumped by electro-optically Q-switched Er:YSGG laser. This laser generated pumping radiation at 2.79 μm with the maximum energy of 50 mJ in 80 ns long pulse with the repetition-rate of 1 Hz. The 25 mm long optical resonator of Fe:ZnSe or Fe:ZnMgSe lasers was formed by a plan dichroic pumping mirror and a concave output coupler (r = 200 mm) with reflectivity 88 % @ 4-5 μm. Both lasers were operated at room temperature. Measured maximum output energy/slope efficiency in respect to the absorbed energy was ~ 3.8 mJ/42 % for the Fe:ZnSe laser and ~ 0.48 mJ/10 % for the Fe:ZnMgSe laser. The generated output pulse duration was 150 - 200 ns in both cases and the output beam spatial profile was approximately gaussian. The Fe:ZnSe and Fe:ZnMgSe lasers output spectra line-width was ~ 200 nm (FWHM) and their maxima were centered at 4.45 μm and 4.8 μm, respectively. The results were compared to pumping the same crystals by a Q-switched Er:YAG laser in similar conditions.

  19. Photoinduced reduction of surface states in Fe:ZnO

    SciTech Connect

    Knut, R. Palmgren, P.; Karis, O.; Lagerqvist, U.; Pohl, A.; Pal, P.; Svedlindh, P.

    2015-05-28

    We report on the electronic structure of nano-crystalline Fe:ZnO, which has recently been found to be an efficient photocatalyst. Using resonant photoemission spectroscopy, we determine the binding energy of Fe 3d states corresponding to different valencies and coordination of the Fe atoms. The photo-activity of ZnO reduces Fe from 3+ to 2+ in the surface region of the nano-crystalline material due to the formation of oxygen vacancies. Electronic states corresponding to low-spin Fe{sup 2+} are observed and attributed to crystal field modification at the surface. These states are potentially important for the photocatalytic sensitivity to visible light due to their location deep in the ZnO bandgap. X-ray absorption and x-ray photoemission spectroscopy suggest that Fe is only homogeneously distributed for concentrations up to 3%. Increased concentrations does not result in a higher concentration of Fe ions in the surface region. This is limiting the photocatalytic functionality of ZnO, where the most efficient Fe doping concentration has been shown to be 1%-4%.

  20. Synthesis, structural and magnetic behavior studies of Zn-Al substituted cobalt ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Zare, Samad; Ati, Ali A.; Dabagh, Shadab; Rosnan, R. M.; Othaman, Zulkafli

    2015-06-01

    A series of nano-sized Zn-Al substituted cobalt ferrite Co(1-x)Zn(x)Fe2-xAlxO4 with 0.0 ⩽ x ⩽ 1.0 have been synthesized by chemical co-precipitation technique. The XRD spectra revealed the single phase spinel structure of Co(1-x)Zn(x)Fe2-xAlxO4 with average size of nanoparticles are estimated to be 17-30 nm. These are small enough to achieve the suitable signal to noise ratio, which is important in the high-density recording media. The FTIR spectra show the characteristic of two strong absorption bands at 560-600 cm-1 corresponds to the intrinsic stretching vibrations of the metal at the tetrahedral site and lowest band is observed at 370-410 cm-1 corresponds to octahedral site. The crystalline structures of nanoparticles composite were characterized by Field Emission Scanning Electron Microscopy (FE-SEM). The magnetic properties such as saturation magnetization, remanence magnetization, and coercivity were calculated from the hysteresis loops. Saturation magnetization were found to increase up to x = 0.4 while remanence magnetization and coercivity continuously decrease with increasing Zn-Al concentration. The stability in coercivity while increase in saturation magnetization confirms that the Co0.6Zn0.4Fe1.6Al0.4O4 ferrite sample is suitable for applications in high-density recording media.

  1. Study of structural and optical properties of Al doped ZnO nanoparticles

    NASA Astrophysics Data System (ADS)

    Mallika, A. N.; Ramachandra Reddy, A.

    2014-03-01

    This paper reports on the structural and optical properties of Al doped ZnO nanoparticles prepared through sol-gel method using poly vinyl alcohol as chelating agent. Al was effectively doped in ZnO with concentrations up to 6 atomic percent concentrations (at. %). X-ray diffraction (XRD) results revealed that all the samples do not have impurity phase indicating hexagonal wurtzite structure of ZnO formed, the average crystallite sizes were decreased with increasing Al concentrations. A compressive strain was induced with Al doping and was calculated with W-H plot analysis. The morphology of all the samples was studied from Field Emission Scanning Electron Microscope (FE-SEM). The energy band gap of the Al doped samples was estimated from UV-Vis spectrum showed an overall increase. The presence of functional groups and chemical bonding of ZnO with Al doping was confirmed by Fourier Transform Infrared Spectroscopy (FTIR) spectra, and in addition to this, the photoluminescence (PL) properties of Al doped ZnO nanoparticles were studied. This paper reports on the structural and optical properties of Al doped ZnO nanoparticles prepared through sol-gel method using poly vinyl alcohol as chelating agent. Al was effectively doped in ZnO with concentrations up to 6 atomic percent concentrations (at. %). X-ray diffraction (XRD) results revealed that all the samples do not have impurity phase indicating hexagonal wurtzite structure of ZnO formed, the average crystallite sizes were decreased with increasing Al concentrations. A compressive strain was induced with Al doping and was calculated with W-H plot analysis. The morphology of all the samples was studied from Field Emission Scanning Electron Microscope (FE-SEM). The energy band gap of the Al doped samples was estimated from UV-Vis spectrum showed an overall increase. The presence of functional groups and chemical bonding of ZnO with Al doping was confirmed by Fourier Transform Infrared Spectroscopy (FTIR) spectra, and in

  2. The mechanical properties of FeAl

    SciTech Connect

    Baker, I.; George, E.P.

    1996-12-31

    Only in the last few years has progress been made in obtaining reproducible mechanical properties data for FeAl. Two sets of observations are the foundation of this progress. The first is that the large vacancy concentrations that exist in FeAl at high temperature are easily retained at low temperature and that these strongly affect the low-temperature mechanical properties. The second is that RT ductility is adversely affected by water vapor. Purpose of this paper is not to present a comprehensive overview of the mechanical properties of FeAl but rather to highlight our understanding of key phenomena and to show how an understanding of the factors which control the yield strength and fracture behavior has followed the discovery of the above two effects. 87 refs, 9 figs.

  3. Optical and EPR spectroscopy of Zn:Cr:ZnSe and Zn:Fe:ZnSe crystals

    NASA Astrophysics Data System (ADS)

    Fedorov, V. V.; Konak, T.; Dashdorj, J.; Zvanut, M. E.; Mirov, S. B.

    2014-11-01

    Optical and EPR characterization of Cr and Fe doped ZnSe crystals annealed in Zn vapor revealed a strong bleaching of the divalent state of transition metal ions. Photo induced EPR kinetics were studied in 20-80 K temperature range. Analysis of time-dependent data reveals Cr1+ signal rise time decreases with increasing temperature. The non-exponential decay of Cr1+ concentration were analyzed using Auger-type recombination process. The photoluminescence quantum yield of Cr2+ ions at 5E(D) → 5T2(D) mid-IR transition excited via chromium ionization process was measured to be close to 100%.

  4. On the crack growth resistance and strength of the B2 iron aluminides Fe-40Al, Fe-45Al, and Fe-10Ni-40Al (at. %)

    SciTech Connect

    Schneibel, J.H.; Maziasz, P.J.

    1994-09-01

    The crack growth resistance and yield strength of the B2 iron aluminides Fe-40Al, Fe-45Al, are Fe-10Ni-40Al (at. %) have been investigated at room temperature laboratory air. After fast cooling from 1273 K, Fe-45Al and Fe-10Ni-40Al are much stronger than Fe-40Al, and exhibit considerably lower crack growth resistance. The crack growth resistance decreases with decreasing crack propagation velocity. Low crack propagation velocities favor intergranular fracture, whereas high velocities can lead to significant contributions from transgranular fracture. Boron additions to Fe-40Al and Fe-10Ni-40Al improve the crack growth resistance, reduce its dependence on the crack propagation velocity, and cause the path to be predominantly transgranular. In a plot of fracture toughness versus yield strength, the properties of the iron aluminides are similar to those of typical aluminum alloys.

  5. Zn interstitial defects induced magnetic nature in Fe ions doped ZnO based DMS

    SciTech Connect

    Pazhanivelu, V. Selvadurai, A. Paul Blessington; Murugaraj, R.

    2015-06-24

    This paper describes the synthesis of Fe doped ZnO samples Zn{sub 1-x}Fe{sub x}0, where x various from 0.01≤x≤0.05 (in steps of 0.01) by solution method. The effect of Fe ions doping on the structural, optical and magnetic properties was investigated using X-ray diffraction (XRD), Photoluminescence and vibrating sample magnetometer (VSM) measurements. The observed result indicates that the samples are single phase formation of the wurtzite structure without any significant secondary phase in it. The photoluminescence spectra reveals the presence of Zn vacancies. The magnetic property of prepared samples was studied using a vibrating sample magnetometer and the observed results revealed a super-paramagnetic behavior for the Fe doped ZnO samples.

  6. Melting, Processing, and Properties of Disordered Fe-Al and Fe-Al-C Based Alloys

    NASA Astrophysics Data System (ADS)

    Satya Prasad, V. V.; Khaple, Shivkumar; Baligidad, R. G.

    2014-09-01

    This article presents a part of the research work conducted in our laboratory to develop lightweight steels based on Fe-Al alloys containing 7 wt.% and 9 wt.% aluminum for construction of advanced lightweight ground transportation systems, such as automotive vehicles and heavy-haul truck, and for civil engineering construction, such as bridges, tunnels, and buildings. The melting and casting of sound, porosity-free ingots of Fe-Al-based alloys was accomplished by a newly developed cost-effective technique. The technique consists of using a special flux cover and proprietary charging schedule during air induction melting. These alloys were also produced using a vacuum induction melting (VIM) process for comparison purposes. The effect of aluminum (7 wt.% and 9 wt.%) on melting, processing, and properties of disordered solid solution Fe-Al alloys has been studied in detail. Fe-7 wt.% Al alloy could be produced using air induction melting with a flux cover with the properties comparable to the alloy produced through the VIM route. This material could be further processed through hot and cold working to produce sheets and thin foils. The cold-rolled and annealed sheet exhibited excellent room-temperature ductility. The role of carbon in Fe-7 wt.% Al alloys has also been examined. The results indicate that Fe-Al and Fe-Al-C alloys containing about 7 wt.% Al are potential lightweight steels.

  7. The electrochemical performances of Zn-Sn-Al-hydrotalcites in Zn-Ni secondary cells

    NASA Astrophysics Data System (ADS)

    Wang, Tingting; Yang, Zhanhong; Yang, Bin; Wang, Ruijuan; Huang, Jianhang

    2014-07-01

    Zn-Sn-Al-hydrotalcites (LDHs) have been successfully prepared by hydrothermal method and applied as a novel anodic active material in Zn-Ni secondary batteries. The scanning electron microscopy (SEM), X-ray diffractometer (XRD) and FT-IR tests are performed to investigate the morphology and microstructure of Zn-Sn-Al-hydrotalcites. Electrochemical performances of Zn-Sn-Al-hydrotalcites with different Zn/Sn/Al molar ratios are investigated through galvanostatic charge-discharge measurements, cyclic voltammograms (CV) and Tafel polarization curves. Compared with Zn-Al-LDH without Sn addition, Zn-Sn-Al-LDHs still present hexagon layer structure, and present more excellent electrochemical performance. And Zn-Sn-Al-LDH with the molar ratio of 2.8:0.2:1 shows a better cycle stability than the other samples. The results demonstrate that Sn addition can help to perfect the electrochemical performance of zinc electrode with Zn-Sn-Al-LDHs. At the same time, CV tests indicate well reversibility and Tafel curves reveal more positive corrosion potential for Zn-Sn-Al-LDHs.

  8. Effects of Bonding Conditions on Bondability Using Zn/Al/Zn Clad Solder

    NASA Astrophysics Data System (ADS)

    Yamaguchi, T.; Ikeda, O.; Oda, Y.; Hata, S.; Kuroki, K.; Kuroda, H.; Hirose, A.

    2015-12-01

    Three-layer Zn/Al/Zn clad solders have been developed for high-temperature die attachment. The clad structure is used to improve the wettability and bondability of Zn-Al eutectic solder by preventing Al oxidation. The effects of the bonding conditions on the bondability with Zn/Al/Zn clad solder were investigated. Bonding was achieved in the temperature range from 385°C to 420°C under N2 atmosphere with oxygen concentration below 100 ppm. However, the bonding strength of the joint formed under N2 + 4% H2 atmosphere was almost 0 MPa, and stripe defects and air gaps remained in the bond layer. To improve the bondability under N2 + 4% H2 and expand the application range, a five-layer Cu/Zn/Al/Zn/Cu clad solder was developed in an attempt to prevent the Zn layers from being oxidized by the outer Cu layers. Cross-sectional observation of the Cu/Zn/Al/Zn/Cu clad solder revealed that the surface was covered by a Cu layer, and that Cu5Zn8 layers grew between the Cu and Zn layers. This clad solder exhibited high shear strength of over 80 MPa when formed under N2 + 4% H2 atmosphere, and no stripe defects or air gaps were observed in the bond layer.

  9. Magnetic Order in TbCo2Zn20 and TbFe2Zn20

    SciTech Connect

    Tian, W.; Christianson, Andrew D; Zarestky, J. L.; Jia, S.; Bud'ko, S. L.; Canfield, P. C.; Piccoli, P. M. B.; Schultz, A. J.

    2010-01-01

    We report neutron di raction studies of TbCo2Zn20 and TbFe2Zn20, two isostructural compounds which exhibit dramatically di erent magnetic behavior. In the case of TbCo2Zn20, magnetic Bragg peaks corresponding to antiferromagnetic order are observed below TN 2.5 K with a propagation vector of (0.5 0.5 0.5). On the other hand, TbFe2Zn20 undergoes a ferromagnetic transition at temperatures as high as 66 K which shows a high sensitivity to sample-to-sample variations. Two samples of TbFe2Zn20 with the same nominal compositions but with substantially di erent mag- netic ordering temperatures (Tc 51 and 66 K) were measured by single crystal neutron di raction. Structural re nements of the neutron di raction data nd no direct signature of atomic site disorder between the two TbFe2Zn20 samples except for subtle di erences in the anisotropic thermal param- eters. The di erences in the anisotropic thermal parameters between the two samples is likely due to very small amounts of disorder. This provides further evidence for the extreme sensitivity of the magnetic properties of TbFe2Zn20 to small sample variations, even small amounts of disorder.

  10. Thermal mixing of Al-Fe multilayers

    NASA Astrophysics Data System (ADS)

    Meyer, M.; Mendoza Zélis, L.; Sánchez, F. H.; Traverse, A.

    1994-12-01

    Al-Fe multilayers have been mixed by thermal treatment and their evolution followed by conversion electron Mössbauer spectroscopy. The initial and final states have been characterized by Rutherford backscattering spectrometry. The results are compared with those previously obtained in the ion beam mixing of similar systems.

  11. Boron strengthening in FeAl

    SciTech Connect

    Baker, I.; Li, X.; Xiao, H.; Klein, O.; Nelson, C.; Carleton, R.L.; George, E.P.

    1998-11-01

    The effect of boron on the strength of B2-structured FeAl is considered as a function of composition, grain size and temperature. Boron does not affect the concentrations of antisite atoms or vacancies present, with the former increasing and the latter decreasing with increasing deviation from the stoichiometric composition. When vacancies are absent, the strength increase per at. % B per unit lattice strain, {Delta}{sigma}/({Delta}c x {epsilon}) increases with increasing aluminum concentration, but when vacancies are present (>45 at. % Al), {Delta}{sigma}/({Delta}c x {epsilon}) decreases again. Boron increases grain size strengthening in FeAl. B strengthening is roughly independent of temperature up to the yield strength peak but above the point, when diffusion-assisted deformation occurs, boron strengthening increases dramatically.

  12. Zn interstitial defects induced magnetic nature in Fe ions doped ZnO based DMS

    NASA Astrophysics Data System (ADS)

    Pazhanivelu, V.; Selvadurai, A. Paul Blessington; Murugaraj, R.

    2015-06-01

    This paper describes the synthesis of Fe doped ZnO samples Zn1-xFex0, where x various from 0.01≤x≤0.05 (in steps of 0.01) by solution method. The effect of Fe ions doping on the structural, optical and magnetic properties was investigated using X-ray diffraction (XRD), Photoluminescence and vibrating sample magnetometer (VSM) measurements. The observed result indicates that the samples are single phase formation of the wurtzite structure without any significant secondary phase in it. The photoluminescence spectra reveals the presence of Zn vacancies. The magnetic property of prepared samples was studied using a vibrating sample magnetometer and the observed results revealed a super-paramagnetic behavior for the Fe doped ZnO samples.

  13. Moessbauer effect and X-ray distribution function analysis in complex Na{sub 2}O-CaO-ZnO-Fe{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-SiO{sub 2} glasses and glass-ceramics

    SciTech Connect

    Romero, M.; Rincon, J.M.; Musik, S.; Kozhukharov, V.

    1999-05-01

    Moessbauer spectroscopy at room temperature was carried out to determine the state of iron ions in complex glasses and glass-ceramics in the SiO{sub 2}-CaO-ZnO-Na{sub 2}O-Fe{sub 2}O{sub 3}-Al{sub 2}O{sub 3} system. Isomer shift values of the glasses suggest that Fe{sup 3+} and Fe{sup 2+} are in tetrahedral and octahedral coordination, respectively. The spectrum of the glass-ceramic shows that about 60 wt% total iron is in the magnetite phase. The Fe{sup +3}/Fe{sup +2} ratio varies with the total iron oxide content of the glasses, indicating that the vitreous network is more distorted when the iron content is greater. X-ray diffraction measurements were carried out to obtain the radial distribution function (RDF). The interatomic distances for Si-Si and Si-O have been determined. The complex composition of these glasses does not allow the estimation of Al-O and Fe-O distances.

  14. Effect of scandium doping on the oxidation resistance of Zn5Al and Zn55Al alloys

    NASA Astrophysics Data System (ADS)

    Obidov, Z. R.; Amonova, A. V.; Ganiev, I. N.

    2013-04-01

    The influence of scandium on the oxidation kinetics of Zn5Al and Zn55Al alloys is studied. It is observed that small additions (0.005-0.05 wt %) of Sc substantially improve the oxidation resistance of zincaluminium alloys.

  15. AlN/Fe/AlN nanostructures for magnetooptic magnetometry

    SciTech Connect

    Lišková-Jakubisová, E. Višňovský, Š.; Široký, P.; Hrabovský, D.; Pištora, J.

    2014-05-07

    AlN/Fe/AlN/Cu nanostructures with ultrathin Fe grown by sputtering on Si substrates are evaluated as probes for magnetooptical (MO) mapping of weak currents. They are considered for a laser wavelength of λ = 410 nm (3.02 eV) and operate at oblique light incidence angles, φ{sup (0)}, to enable detection of both in-plane and out-of-plane magnetization. Their performance is evaluated in terms of MO reflected wave electric field amplitudes. The maximal MO amplitudes in AlN/Fe/AlN/Cu are achieved by a proper choice of layer thicknesses. The nanostructures were characterized by MO polar Kerr effect at φ{sup (0)} ≈ 5° and longitudinal Kerr effect spectra (φ{sup (0)} = 45°) at photon energies between 1 and 5 eV. The nominal profiles were refined using a model-based analysis of the spectra. Closed form analytical expressions are provided, which are useful in the search for maximal MO amplitudes.

  16. Zinc and iron metabolism in Euglena gracilis: metal redistribution during Zn and Fe deficiency

    SciTech Connect

    Taylor, P.; Gingrich, D.; Antholine, W.E.; Petering, D.H.

    1986-05-01

    The normal cytosolic distribution of Zn and Fe in Euglena gracilis and their changes during Zn and Fe deficiency and repletion in relationship to cell proliferation were examined. Using Sephadex G-75 chromatography, two metal pools were found-Zn and Fe bound to high molecular weight (HMW) proteins and a pool of low molecular weight (LMW) Zn and Fe of less than 2000 daltons (ZnL, FeL), containing 80-90% of the cytosolic Zn and Fe. ZnL and FeL can be separated on Sephadex G-15 and by HPLC techniques. According to ESR analysis both HMW and LMW iron is high spin Fe(III). Under conditions of Zn deficiency, cell proliferation is halted after 48 hrs. in concert with the depletion of the ZnL. Within error, HMW protein bound Zn is unaffected. ZnL appears to be a labile store of Zn to supply the cell with this essential metal. In contrast, during Fe deficiency cell proliferation is unaffected. Yet both HMW and LMW pools are depleted within 48 hrs. Both bands of Fe appear to be storage forms of the metal. Proliferative capacity of the alga is evidently more sensitive to Zn deficiency than to Fe depletion, possibly because Euglena can scavenge adventitious Fe from the medium by a siderophore-mediated mechanism.

  17. Room temperature luminescence and ferromagnetism of AlN:Fe

    NASA Astrophysics Data System (ADS)

    Li, H.; Cai, G. M.; Wang, W. J.

    2016-06-01

    AlN:Fe polycrystalline powders were synthesized by a modified solid state reaction (MSSR) method. Powder X-ray diffraction and transmission electron microscopy results reveal the single phase nature of the doped samples. In the doped AlN samples, Fe is in Fe2+ state. Room temperature ferromagnetic behavior is observed in AlN:Fe samples. Two photoluminescence peaks located at about 592 nm (2.09 eV) and 598 nm (2.07 eV) are observed in AlN:Fe samples. Our results suggest that AlN:Fe is a potential material for applications in spintronics and high power laser devices.

  18. Methotrexate intercalated ZnAl-layered double hydroxide

    SciTech Connect

    Chakraborty, Manjusha; Dasgupta, Sudip; Soundrapandian, Chidambaram; Chakraborty, Jui; Ghosh, Swapankumar; Mitra, Manoj K.; Basu, Debabrata

    2011-09-15

    The anticancerous drug methotrexate (MTX) has been intercalated into an ZnAl-layered double hydroxide (LDH) using an anion exchange technique to produce LDH-MTX hybrids having particle sizes in the range of 100-300 nm. X-ray diffraction studies revealed increases in the basal spacings of ZnAl-LDH-MTX hybrid on MTX intercalation. This was corroborated by the transmission electron micrographs, which showed an increase in average interlayer spacing from 8.9 A in pristine LDH to 21.3 A in LDH-MTX hybrid. Thermogravimetric analyses showed an increase in the decomposition temperature for the MTX molecule in the LDH-MTX hybrid indicating enhanced thermal stability of the drug molecule in the LDH nanovehicle. The cumulative release profile of MTX from ZnAl-LDH-MTX hybrids in phosphate buffer saline (PBS) at pH 7.4 was successfully sustained for 48 h following Rigter-Peppas model release kinetics via diffusion. - Graphical abstract: ZnAl-layered double hydroxide intercalated with methotrexate ({approx}34% loading) promises the possibility of use of ZnAl-LDH material as drug carrier and in controlled delivery. Highlights: > ZnAl-layered double hydroxide methotrexate nanohybrid has been synthesized. > XRD and TEM studies on nanohybrid revealed successful intercalation of methotrexate. > TG and CHN analyses showed {approx}34 wt% of methotrexate loading into the nanohybrid. > Possibility of use of ZnAl-LDH material as drug carrier and in delivery.

  19. Forging of FeAl intermetallic compounds

    SciTech Connect

    Flores, O.; Juarez, J.; Campillo, B.; Martinez, L.; Schneibel, J.H.

    1994-09-01

    Much activity has been concentrated on the development of intermetallic compounds with the aim of improving tensile ductility, fracture toughness and high notch sensitivity in order to develop an attractive combination of properties for high and low temperature applications. This paper reports experience in processing and forging of FeAl intermetallic of B2 type. During the experiments two different temperatures were employed, and the specimens were forged after annealing in air, 10{sup {minus}2} torr vacuum and argon. From the results it was learned that annealing FeAl in argon atmosphere prior to forging resulted in better deformation behavior than for the other two environments. For the higher forging temperature used in the experiments (700C), the as-cast microstructure becomes partially recrystallized.

  20. Stability and thermal transformation studies of Zn2+- and Fe2+- loaded zeolite Y prepared from Egyptian kaolin

    NASA Astrophysics Data System (ADS)

    EL-Mekkawi, Doaa M.; Ibrahim, Fatma A.; Selim, Mohamed M.

    2015-10-01

    The stability and thermal transformation of Zn2+ and Fe2+- zeolites based kaolin were studied with respect to their loading experimental conditions. Zeolite Y prepared from Egyptian kaolin was used in our investigations. Zeolite shows different degrees of framework stability according to the type of cation and the loading experimental conditions. The obtained data indicate the predominance of adsorption and ion exchange mechanisms during Fe2+ and Zn2+ loading, respectively. The loading experimental conditions also greatly affect the solid-solid interactions of transition metal-zeolites at elevated temperatures. ZnAl2O4 and silica phases were formed upon thermal treatment of Zn-Y zeolites. The ratio of ZnAl2O4 to silica phases increases as the amount of loaded Zn2+ increases in the corresponding unheated zeolites. However, nepheline phase was obtained upon heating Fe-Y zeolites loaded at low initial Fe2+ concentrations. Upon increasing of loaded Fe2+, iron oxide beside other amorphous phases from silica, alumina and/or aluminosilicates were obtained.

  1. Magnetic properties of ZnFe2O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Guskos, Niko; Glenis, Spiros; Typek, Janusz; Zolnierkiewicz, Grzegorz; Berczynski, Pawel; Wardal, Kamil; Guskos, Aleksander; Sibera, Daniel; Moszyński, Dariusz; Lojkowski, Witold; Narkiewicz, Urszula

    2012-04-01

    Fine particles of ZnFe2O4 were synthesized by a wet chemical method in the (80 wt.% Fe2O3 + 20 wt.% ZnO) system. The morphological and structural properties of the mixed system were investigated by scanning electron microscopy, X-ray diffraction, inductively coupled plasma atomic emission, and X-ray photoelectron spectroscopy. The major phase was determined to be the ZnFe2O4 spinel with particle size of 11 nm. The magnetic properties of the material were investigated by ferromagnetic resonance (FMR) in the temperature range from liquid helium to room temperature. A very intense, asymmetric FMR signal from ZnFe2O4 nanoparticles was recorded, which has been analyzed in terms of two Callen-lineshape lines. Temperature dependence of the FMR parameters was obtained from fitting the experimental lines with two component lines. Analysis of the FMR spectra in terms of two separate components indicates the presence of strongly anisotropic magnetic interactions.

  2. Properties of impurity-bearing ferrihydrite II: Insights into the surface structure and composition of pure, Al- and Si-bearing ferrihydrite from Zn(II) sorption experiments and Zn K-edge X-ray absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Cismasu, A. Cristina; Levard, Clément; Michel, F. Marc; Brown, Gordon E.

    2013-10-01

    Naturally occurring ferrihydrite often contains impurities such as Al and Si, which can impact its chemical reactivity with respect to metal(loid) adsorption and (in)organic or microbially induced reductive dissolution. However, the surface composition of impure ferrihydrites is not well constrained, and this hinders our understanding of the factors controlling the surface reactivity of these nanophases. In this study, we conducted Zn(II) adsorption experiments combined with Zn K-edge X-ray absorption spectroscopy measurements on pure ferrihydrite (Fh) and Al- or Si-bearing ferrihydrites containing 10 and 20 mol% Al or Si (referred to as 10AlFh, 20AlFh and 10SiFh, 20SiFh) to evaluate Zn(II) uptake in relation to Zn(II) speciation at their surfaces. Overall, Zn(II) uptake at the surface of AlFh is similar to that of pure Fh, and based on Zn K-edge EXAFS data, Zn(II) speciation at the surface of Fh and AlFh also appears similar. Binuclear bidentate IVZn-VIFe complexes (at ∼3.46 Å (2C[1]) and ∼3.25 Å (2C[2])) were identified at low Zn(II) surface coverages from Zn K-edge EXAFS fits. With increasing Zn(II) surface coverage, the number of second-neighbor Fe ions decreased, which was interpreted as indicating the formation of IVZn polymers at the ferrihydrite surface, and a deviation from Langmuir uptake behavior. Zn(II) uptake at the surface of SiFh samples was more significant than at Fh and AlFh surfaces, and was attributed to the formation of outer-sphere complexes (on average 24% of sorbed Zn). Although similar Zn-Fe/Zn distances were obtained for the Zn-sorbed SiFh samples, the number of Fe second neighbors was lower in comparison with Fh. The decrease in second-neighbor Fe is most pronounced for sample 20SiFh, suggesting that the amount of reactive surface Fe sites diminishes with increasing Si content. Although our EXAFS results shown here do not provide evidence for the existence of Zn-Al or Zn-Si complexes, their presence is not excluded for Zn-sorbed Al

  3. Non-linear Electrical Characteristics of ZnO Modified by Trioxides Sb2O3, Bi2O3, Fe2O3, Al2O3 and La2O3

    NASA Astrophysics Data System (ADS)

    Mekap, Anita; Das, Piyush R.; Choudhary, R. N. P.

    2016-08-01

    The non-linear behavior of polycrystalline-ZnO-based voltage-dependent resistors is considered in the present study. A high-temperature solid-state reaction route was used to synthesize polycrystalline samples of ZnO modified by small amounts of the trioxides Sb2O3, Bi2O3, Fe2O3, etc. in various proportions. X-ray diffraction and scanning electron microscopy techniques were used to study the structural and microstructural characteristics of modified ZnO. Detailed studies of non-linear phenomena of the I-V characteristics, dielectric permittivity ( ɛ r), impedance ( Z), etc. of the samples have provided many interesting results. All the samples exhibited dielectric anomaly. Non-linear variation in polarization with electric field for all the samples was observed. Moreover, significant non-linearity in the I-V characteristics was observed in the breakdown region of all the samples at room temperature. The non-linear coefficient ( α) in different cases, i.e. for I- V, ɛ r- f, ɛ r- T, and ɛ r- Z, was calculated and found to be appreciable. The frequency dependence of ac conductivity suggests that the material obeys Jonscher's universal power law.

  4. Catalytic Methane Decomposition over Fe-Al2 O3.

    PubMed

    Zhou, Lu; Enakonda, Linga Reddy; Saih, Youssef; Loptain, Sergei; Gary, Daniel; Del-Gallo, Pascal; Basset, Jean-Marie

    2016-06-01

    The presence of a Fe-FeAl2 O4 structure over an Fe-Al2 O3 catalysts is demonstrated to be vital for the catalytic methane decomposition (CMD) activity. After H2 reduction at 750 °C, Fe-Al2 O3 prepared by means of a fusion method, containing 86.5 wt % FeAl2 O4 and 13.5 wt % Fe(0) , showed a stable CMD activity at 750 °C for as long as 10 h. PMID:27159367

  5. Nanocluster formation in Co/Fe implanted ZnO

    NASA Astrophysics Data System (ADS)

    Bharuth-Ram, K.; Masenda, H.; Doyle, T. B.; Geburt, S.; Ronning, C.

    2015-04-01

    Conversion electron Mössbauer Spectroscopy (CEMS) measurements were made on a ZnO single crystal sample implanted at room temperature (RT) with of 145 and 345 keV 59Co ions with respective fluences of 1.15×1016 ions/cm 2 and 4.17×1016 ions/cm 2, followed by implantation of 60 keV 57Fe to a fluence of 0.50×1016/cm 2 to yield a `box-shaped' implantation profile with a Co + Fe concentration of about 3.2 at. %. CEM spectra were collected after annealing the sample up to 973 K. The spectra after annealing up to 973 K are similar to spectra observed in other CEMS studies on Fe implanted ZnO, but show a dramatic change after the 973 K annealing step; it is dominated by a doublet component with fit parameters typical of Fe 3+. Magnetization curves of the sample after the 973 K anneal show hysteresis, with a small residual magnetization at RT that increases at 4 K. The saturation magnetization at 4 K was approximately 0.33 μ B/CoFe ion, in good agreement with observations for 5-8 nm sized Co nanoclusters in ZnO.

  6. Preparation and photo-catalytic activities of FeOOH/ZnO/MMT composite

    NASA Astrophysics Data System (ADS)

    Zhou, Yao; Liu, Fusheng; Yu, Shitao

    2015-11-01

    Montmorillonite (MMT) was used as the carrier for synthesis of FeOOH and FeOOH/ZnO nano-material. FeOOH and FeOOH/ZnO were synthesized by the aqueous solutions of Fe(NO3)3-HNO3 and Zn(NO3)2-NaOH/Fe(NO3)3-HNO3 with the carrier of montmorillonite respectively. Transmission electron-microscopy (TEM) and X-ray diffraction (XRD) were used to study the morphology form and structure of the nano-materials. TEM was also used to demonstrate that FeOOH/ZnO can be formed with the appropriate interface. According to UV-vis absorption spectra, FeOOH/ZnO has a better response to visible light than FeOOH and ZnO, which indicates there is some coupling effect between FeOOH and ZnO. Pentachlorophenol (PCP) was used as a representative organic pollutant to evaluate the photo-catalytic efficiency of the FeOOH/ZnO and FeOOH catalysts in visible light (λ > 400 nm). The photo-catalytic efficiency of FeOOH/ZnO/MMT is better than FeOOH/MMT. According to FTIR, changes of pH and TOC, the degradation mechanism was also discussed. PCP was degraded to aromatic ketone and chloro-hydrocarbon compounds and then to H2O, CO2 and HCl.

  7. Microstructure and Solderability of Zn-6Al- xSn Solders

    NASA Astrophysics Data System (ADS)

    Yang, Xiaojun; Hu, Wei; Yan, Xin; Lei, Yongping

    2015-04-01

    The eutectic point of Zn-6Al alloy is 381°C, and the peritectic reaction of Zn-Al-Sn alloy occurs at 280°C. In order to find an alloy with an appropriate melting point between 280°C and 340°C, Zn-6Al-5Sn, Zn-6Al-10Sn, Zn-6Al-15Sn, and Zn-6Al-20Sn alloys were prepared. The microstructure, melting behavior, and wettability of the Zn-6Al- xSn solder alloys were investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and the sessile drop method. The results show that the alloys were composed of Zn-rich phase, Zn-Al structure, Sn-Zn-Al peritectic structure, and Sn-Zn eutectic structure. The progressive decrease of the liquidus temperature of the Zn-6Al- xSn solders was confirmed by the DSC results in the order: Zn-6Al-5Sn, Zn-6Al-10Sn, Zn-6Al-15Sn, Zn-6Al-20Sn. A decrease of the wetting angle, selected for evaluation of the solderability of the Zn-6Al- xSn solders, was observed in the same order. The cross-section of a solder joint on a Cu substrate was examined by SEM coupled with energy-dispersive x-ray (EDS) analysis.

  8. Ferromagnetic Fe2CrAl Nanowires

    NASA Astrophysics Data System (ADS)

    Dulal, Rajendra; Dahal, Bishnu; Pegg, Ian L.; Philip, John

    Heusler alloy Fe2CrAl (FCA) nanowires were grown on silicon substrates. Nanowires have diameters in the range 50 to 200 nm and lengths up to 100 µm. They exhibit cubic L21 and A2 type structure with a space group, Pm m. Magnetic characterization reveals that they display ferromagnetic behavior and has a Curie temperature above 400 K. Magnetic behavior of FCA nanowires is different from the reported bulk behavior. Bulk FCA with L21 structure has a Curie temperature around 274 K. National Science Foundation under ECCS-0845501 and NSF-MRI, DMR-0922997.

  9. Synthesis and properties of A{sub 6}B{sub 2}(OH){sub 16}Cl{sub 2}.4H{sub 2}O (A = Mg, Ni, Zn, Co, Mn and B = Al, Fe) materials for environmental applications

    SciTech Connect

    Dias, Anderson; Cunha, Lumena; Vieira, Andiara C.

    2011-09-15

    Highlights: {yields} A{sub 6}B{sub 2}(OH){sub 16}Cl{sub 2}.4H{sub 2}O (A = Mg, Ni, Zn, Co, Mn and B = Al, Fe) materials were synthesized. {yields} Chemical synthesis produced different levels of crystallinity and ordering degree. {yields} Structural investigation by Raman scattering revealed a complex band structure. {yields} A strong correlation between band structure and ionic radius was determined. -- Abstract: Double layered hydroxide materials of composition A{sub 6}B{sub 2}(OH){sub 16}Cl{sub 2}.4H{sub 2}O (A = Mg, Ni, Zn, Co, Mn and B = Al, Fe) were synthesized by chemical precipitation at 60 {sup o}C. Different levels of crystallinity and ordering degree were observed depending upon the chemical environment or the combination between divalent and trivalent cations. The results from high-resolution transmission electron microscopy revealed that nanostructured layered samples were obtained with interplanar spacing compatible with previous literature. Raman scattering was employed to investigate the complex band structure observed, particularly the lattice vibrations at lower frequencies, which is intimately correlated to the cationic radius of both divalent and trivalent ions. The results showed that strongly coordinated water and chloride ions besides highly structured hydroxide layers have a direct influence on the stability of the hydrotalcites. It was observed that transition and decomposition temperatures varied largely for different chemical compositions.

  10. Overview of the development of FeAl intermetallic alloys

    SciTech Connect

    Maziasz, P.J.; Liu, C.T.; Goodwin, G.M.

    1995-09-01

    B2-phase FeAl ordered intermetallic alloys based on an Fe-36 at.% Al composition are being developed to optimize a combination of properties that includes high-temperature strength, room-temperature ductility, and weldability. Microalloying with boron and proper processing are very important for FeAl properties optimization. These alloys also have the good to outstanding resistance to oxidation, sulfidation, and corrosion in molten salts or chlorides at elevated temperatures, characteristic of FeAl with 30--40 at.% Al. Ingot- and powder-metallurgy (IM and PM, respectively) processing both produce good properties, including strength above 400 MPa up to about 750 C. Technology development to produce FeAl components for industry testing is in progress. In parallel, weld-overlay cladding and powder coating technologies are also being developed to take immediate advantage of the high-temperature corrosion/oxidation and erosion/wear resistance of FeAl.

  11. Energetic ion bombarded Fe/Al multilayers

    SciTech Connect

    Al-Busaidy, M.S.; Crapper, M.D.

    2006-05-15

    The utility of ion-assisted deposition is investigated to explore the possibility of counteracting the deficiency of back-reflected current of Ar neutrals in the case of lighter elements such as Al. A range of energetically ion bombarded Fe/Al multilayers sputtered with applied surface bias of 0, -200, or -400 V were deposited onto Si(111) substrates in an argon atmosphere of 4 mTorr using a computer controlled dc magnetron sputtering system. Grazing incidence reflectivity and rocking curve scans by synchrotron x rays of wavelength of 1.38 A were used to investigate the structures of the interfaces produced. Substantial evidence has been gathered to suggest the gradual suppression of interfacial mixing and reduction in interfacial roughness with increases of applied bias. The densification of the Al microstructure was noticeable and may be a consequence of resputtering attributable to the induced ion bombardment. The average interfacial roughnesses were calculated for the 0, -200, and -400 V samples to be 7{+-}0.5, 6{+-}0.5, and 5{+-}0.5 A respectfully demonstrating a 30% improvement in interface quality. Data from rocking curve scans point to improved long-range correlated roughness in energetically deposited samples. The computational code based on the recursive algorithm developed by Parratt [Phys. Rev. 95, 359 (1954)] was successful in the simulation of the specular reflectivity curves.

  12. Zn-exchange and Mössbauer studies on the [Fe-Fe] derivatives of the purple acid Fe(III)-Zn(II)-phosphatase from kidney beans.

    PubMed

    Suerbaum, H; Körner, M; Witzel, H; Althaus, E; Mosel, B D; Müller-Warmuth, W

    1993-05-15

    In order to perform Mössbauer studies, Zn(II) in the Fe(III)-Zn(II) purple acid phosphatase of the red kidney bean has been exchanged by incubating the semiapoenzyme with 57Fe(II). The resulting Fe(III)-57Fe(II) enzyme has 125% activity, compared with that of the Zn(II) enzyme. It can be oxidized by H2O2 or peroxydisulfate to the Fe(III)-57Fe(III) species with a 30-times lower activity. Incubation of the metal-free apoenzyme with 57Fe(II) in the presence of O2 leads to the 57Fe(III)-57Fe(II) species which is stable in dilute solutions, but partially oxidized during the concentration procedure to the 57Fe(III)-57Fe(III) enzyme. Limited reduction of the oxidized enzyme with ascorbate delivers a mixture of the Fe(II)-Fe(II)/Fe(III)-Fe(III) species, but not the mixed valent Fe(III)-Fe(II) species, indicating that after the transfer of the first electron the second electron of the ascorbate radical is immediately transferred to the second Fe(III). The Mössbauer spectra of the oxidized species show at 4.2 K two quadrupole doublets with delta of 0.51 mm/s and 0.53 mm/s and delta E of 1.46 and 0.96 mm/s indicating high spin Fe(III) in two different binding sites, obviously with a higher asymmetry in the chromophoric Fe(III) site. The values are too low for a mu-oxo bridge. The mixed-valent Fe(III)-Fe(II) species shows two quadrupole doublets with delta values of 0.55 mm/s and 1.14 mm/s and delta E values of 1.43 mm/s and 3.01 mm/s at 70 K for high spin Fe(II) and Fe(III), but the signal of the Fe(II) component shows magnetic patterns at 4.2 K indicating a half-integer spin system with antiferromagnetic coupling. The Fe(II)-Fe(II) system exhibits two quadrupole doublets with delta values of 1.18 mm/s and 1.22 mm/s and with delta E values of 3.69 mm/s and 2.68 mm/s again indicating a higher asymmetry in the originally chromophoric Fe(III)-binding site. Addition of phosphate shows only minor differences in the oxidized enzyme and in the mixed valent Fe(III)-Fe(II) system

  13. Interplay between chemical state, electric properties, and ferromagnetism in Fe-doped ZnO films

    SciTech Connect

    Chen, G.; Peng, J. J.; Song, C.; Zeng, F.; Pan, F.

    2013-03-14

    Valence state of Fe ions plays an important role in the physical properties of Fe doped ZnO films. Here, a series of Zn{sub 1-x}Fe{sub x}O films with different Fe concentrations (x = 0, 2.3, 5.4, 7.1, and 9.3 at. %) were prepared to investigate their structural, piezoelectric, ferroelectric, bipolar resistive switching properties, and electrical-control of ferromagnetism at room temperature. The structure characterizations indicate that the chemical state of Fe ions substituting Zn{sup 2+} site changes from Fe{sup 3+} to Fe{sup 2+} with the increase of Fe dopant concentration. We found enhanced piezoelectric and ferroelectric properties in Zn{sub 0.977}Fe{sub 0.023}O films with more Fe{sup 3+} due to the smaller Fe{sup 3+} ionic size in comparison with Zn{sup 2+} while the increase of Fe{sup 2+} concentration by a larger amount of Fe dopant results in the worse ferroelectric and piezoelectric performance. All Pt/Zn{sub 1-x}Fe{sub x}O/Pt devices show bipolar resistive switching properties. Especially, devices with lower Fe dopant concentration exhibit better endurance properties due to their higher crystalline quality. The variation of oxygen vacancies during resistive switching provides an opportunity to tune ferromagnetism of Fe-doped ZnO films, giving rise to the integration of charge and spin into a simple Pt/Zn{sub 1-x}Fe{sub x}O/Pt devices. The multifunctional properties of Fe-doped ZnO films are promising for communication systems and information storage devices.

  14. The redox state of arc mantle using Zn/Fe systematics.

    PubMed

    Lee, Cin-Ty A; Luffi, Peter; Le Roux, Véronique; Dasgupta, Rajdeep; Albaréde, Francis; Leeman, William P

    2010-12-01

    Many arc lavas are more oxidized than mid-ocean-ridge basalts and subduction introduces oxidized components into the mantle. As a consequence, the sub-arc mantle wedge is widely believed to be oxidized. The Fe oxidation state of sub-arc mantle is, however, difficult to determine directly, and debate persists as to whether this oxidation is intrinsic to the mantle source. Here we show that Zn/Fe(T) (where Fe(T) = Fe(2+) + Fe(3+)) is redox-sensitive and retains a memory of the valence state of Fe in primary arc basalts and their mantle sources. During melting of mantle peridotite, Fe(2+) and Zn behave similarly, but because Fe(3+) is more incompatible than Fe(2+), melts generated in oxidized environments have low Zn/Fe(T). Primitive arc magmas have identical Zn/Fe(T) to mid-ocean-ridge basalts, suggesting that primary mantle melts in arcs and ridges have similar Fe oxidation states. The constancy of Zn/Fe(T) during early differentiation involving olivine requires that Fe(3+)/Fe(T) remains low in the magma. Only after progressive fractionation does Fe(3+)/Fe(T) increase and stabilize magnetite as a fractionating phase. These results suggest that subduction of oxidized crustal material may not significantly alter the redox state of the mantle wedge. Thus, the higher oxidation states of arc lavas must be in part a consequence of shallow-level differentiation processes, though such processes remain poorly understood. PMID:21124454

  15. Current Transport in Al-Diffused ZnO/Si Heterostructures

    NASA Astrophysics Data System (ADS)

    Chen, Yen-Jen; Tong, Chong; Yun, Juhyung; Anderson, Wayne A.

    2015-01-01

    The current-voltage-temperature (I-V-T) characteristics of transparent Al-doped ZnO (AZO) on n-Si heterojunction structures were analyzed with respect to two different Al diffusion temperatures, 200°C and 600°C. Thin films of Al were deposited on top of the ZnO/Si structures, followed by introducing the Al atoms into the ZnO to form AZO through a process of thermal diffusion. Measurements at temperatures of 150-400 K were carried out in order to understand the temperature dependence of the heterostructure diode characteristics for photovoltaic applications. The results indicated the difference in current mechanisms observed in the two diodes with different Al-diffusion temperatures and Al thicknesses. The charge transport mechanism in the 200°C diodes indicated thermionic field emission (TFE) as the dominating mechanism, whereas the 600°C diodes resulted in field emission (FE) as the dominating current transport. The differences in conduction mechanisms explain the better solar cell performance using the 200°C process.

  16. Damage annealing in low temperature Fe/Mn implanted ZnO

    NASA Astrophysics Data System (ADS)

    Gunnlaugsson, H. P.; Bharuth-Ram, K.; Johnston, K.; Langouche, G.; Mantovan, R.; Mølholt, T. E.; Naidoo, D.; Ólafsson, O.; Weyer, G.

    2015-04-01

    57Fe Emission Mössbauer spectra obtained after low fluence (<1012 cm -2) implantation of 57Mn ( T 1/2= 1.5 min.) into ZnO single crystal held at temperatures below room temperature (RT) are presented. The spectra can be analysed in terms of four components due to Fe 2+ and Fe 3+ on Zn sites, interstitial Fe and Fe in damage regions (Fe D ). The Fe D component is found to be indistinguishable from similar component observed in emission Mössbauer spectra of higher fluence (˜1015 cm -2)57Fe/ 57Co implanted ZnO and 57Fe implanted ZnO, demonstrating that the nature of the damage regions in the two types of experiments is similar. The defect component observed in the low temperature regime was found to anneal below RT.

  17. Study of Phase Relations of ZnO-Containing Fayalite Slag Under Fe Saturation

    NASA Astrophysics Data System (ADS)

    Shi, Huayue; Chen, Liugang; Malfliet, Annelies; Jones, Peter Tom; Blanpain, Bart; Guo, Muxing

    2016-06-01

    A ZnO-containing fayalite-based slag can be formed in copper smelting from secondary raw materials and its high viscosity is a common issue that hinders slag tapping. In this work, the crystallization behavior of the industrial slag was observed in situ by confocal laser scanning microscopy. Solid precipitation was found to be the major cause of the poor slag fluidity. The phase relations in the industrial slag system ZnO-"FeO"-SiO2-Al2O3-CaO (CaO/SiO2 = 0.05, Al2O3/SiO2 = 0.15) were investigated by quenching the samples after reaching equilibrium at 1423 K (1150 °C) under iron saturation. The equilibrium composition of the phases was determined with electron probe micro-analysis. The effect of individual components, such as FeO, ZnO, and CaO on the phase equilibrium of the slag system has been quantitatively studied. The relation between the solid-phase fraction and the chemical composition of the slag has been revealed. Suggestions to modify the slag composition toward low viscosity are provided.

  18. Long range order and vacancy properties in Al-rich Fe{sub 3}Al and Fe{sub 3}Al(Cr) alloys

    SciTech Connect

    Kim, S.M.; Morris, D.G.

    1998-05-01

    Neutron powder diffraction measurements have been carried out in situ from room temperature to about 100 C in Fe28Al (28 at.% Al), Fe32.5Al (32.5 at.% Al) and Fe28Al15Cr (28 at.% Al, 5 at.% Cr) alloys. X-ray diffraction and TEM studies provided supporting information. The data were analyzed to obtain information about the temperature dependence of the DO{sub 3} and B2 long range order parameters, the location of the Cr atoms and their effect on the ordering energies, and on the vacancy formation and migration properties in Fe28Al and Fe32.5Al alloys. The location of the ternary alloying addition in DO{sub 3} and B2 ordered Al-rich Fe{sub 3}Al is shown to be consistent with considerations of interatomic bond energies.

  19. Nanoparticles of pure and substituted maghemites (gamma-M(x)Fe(2_x)O3 where M = Al, Cr, Mn, Zn and 0 < or = x < or = 1.3): a comparative study.

    PubMed

    Prasad, N K; Gohri, V; Bahadur, D

    2011-03-01

    Magnetic nanoparticles of pure and substituted iron oxides are prepared by single step autocombustion or by wet chemical methods. The nanoparticles prepared by the first process had mixed phase of hematite and maghemite whereas the later essentially gives maghemite phase. XRD patterns and TEM micrographs of the pure and substituted maghemites samples suggest about their monophasic nature and inverse spinel structure. Further, the size of the particles for the above iron oxide samples was found to be in the range of 4 to 30 nm. Saturation magnetization value for the samples was observed to be varying with the type and the amount of substitution. For example, magnetization value initially increased and then decreased for Al- and Mn-substitutions but it continuously decreased for Cr- and Zn-substitutions. Contrary to the saturation magnetization value, the Curie temperature decreased continuously with increased substitutions irrespective of the type of substitutions. Due to higher magnetization value of Mn-substituted maghemite (for x = 0.2, 78 Am2/kg), it has higher heating ability and specific absorption rate compared to Al-substituted maghemite (for x = 0.07, 70 Am2/kg) and pure maghemite (62 Am2/kg). PMID:21449460

  20. Preparation, structural and optical characterization of ZnO, ZnO: Al nanopowder

    SciTech Connect

    Mohan, R. Raj; Rajendran, K.; Sambath, K.

    2014-01-28

    In this paper, ZnO and ZnO:Al nanopowders have been synthesized by low cost hydrothermal method. Zinc nitrate, hexamethylenetetramine (HMT) and aluminium nitrate are used as precursors for ZnO and AZO with different molar ratios. The structural and optical characterization of doped and un-doped ZnO powders have been investigated by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDAX), photoluminescence (PL) and ultra violet visible (UV-Vis) absorption studies. The SEM results show that the hydrothermal synthesis can be used to obtain nanoparticles with different morphology. It is observed that the grain size of the AZO nanoparticles increased with increasing of Al concentration. The PL measurement of AZO shows that broad range of green emission around 550nm with high intensity. The green emission resulted mainly because of intrinsic defects.

  1. Electron trapping on Fe(3+) sites in photodoped ZnO colloidal nanocrystals.

    PubMed

    Zhou, Dongming; Kittilstved, Kevin R

    2016-07-12

    The effects of photodoping on the electronic structure of Fe(3+)-doped ZnO colloidal nanocrystals are presented. We observe disappearance of the spectroscopic signatures attributed to both substitutional Fe(3+) and interstitial Fe(3+) in the ZnO host as a function of photodoping time, which precede the appearance of the well-known localized surface plasmon resonance from conduction band electrons in ZnO nanocrystals. These results suggest that the oxidation state of Fe(3+) defects can be reversibly switched in ZnO nanocrystals. PMID:26948027

  2. Microstructure of the Al-La-Ni-Fe system

    SciTech Connect

    Vasil’ev, A. L.; Ivanova, A. G.; Bakhteeva, N. D.; Kolobylina, N. N.; Orekhov, A. S.; Presnyakov, M. Yu.; Todorova, E. V.

    2015-01-15

    The microstructure of alloys based on the Al-La-Ni-Fe system, which are characterized by a unique ability to form metal glasses and nanoscale composites in a wide range of compositions, has been investigated. Al{sub 85}Ni{sub 7}Fe{sub 4}La{sub 4} and Al{sub 85}Ni{sub 9}Fe{sub 2}La{sub 4} alloys have been analyzed by electron microscopy (including high-resolution scanning transmission electron microscopy), energy-dispersive X-ray microanalysis, electron diffraction (ED), and X-ray diffraction (XRD). It is found that, along with fcc Al and Al{sub 4}La (Al{sub 11}La{sub 3}) particles, these alloys contain a ternary phase Al{sub 3}Ni{sub 1−x}Fe{sub x} (sp. gr. Pnma) isostructural to the Al{sub 3}Ni phase and a quaternary phase Al{sub 8}Fe{sub 2−x}Ni{sub x}La isostructural to the Al{sub 8}Fe{sub 2}Eu phase (sp. gr. Pbam). The unit-cell parameters of the Al{sub 3}Ni{sub 1−x}Fe{sub x} and Al{sub 8}Fe{sub 2−x}Ni{sub x}La compounds, determined by ED and refined by XRD, are a = 0.664(1) nm, b = 0.734(1) nm, and c = 0.490(1) nm for Al{sub 3}Ni{sub 1−x}Fe{sub x} and a = 1.258(3) nm, b = 1.448(3) nm, and c = 0.405(8) nm for Al{sub 8}Fe{sub 2−x}Ni{sub x}La. In both cases Ni and Fe atoms are statistically arranged, and no ordering is found. Al{sub 8}Fe{sub 2−x}Ni{sub x}La particles contain inclusions in the form of Al{sub 3}Fe δ layers.

  3. Growth and properties of electrodeposited transparent Al-doped ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Baka, O.; Mentar, L.; Khelladi, M. R.; Azizi, A.

    2015-12-01

    Al-doped zinc oxide (AZO) nanostructures were fabricated on fluorine-doped tin-oxide (FTO)- coated glass substrates by using electrodeposition. The effects of the doping concentration of Al on the morphological, microstructural, electrical and optical properties of the nanostructures were investigated. From the field emission scanning electron microscopy (FE-SEM) observation, when the amount of Al was increased in the solution, the grains size was observed to decreases. The observed changes in the morphology indicate that Al acts as nucleation centers in the vacancy sites of ZnO and destroys the crystalline structure at high doping level. Effectively, the X-ray diffraction (XRD) analysis indicated that the undoped and the doped ZnO nanostructures has a polycrystalline nature and a hexagonal wurtzite structure with a (002) preferential orientation. The photoluminescence (PL) room-temperature measurements showed that the incorporation of Al in the Zn lattice can improve the intensity of ultraviolet (UV) emission, thus suggesting its greater prospects for use in UV optoelectronic devices.

  4. Fe, Ni and Zn speciation, in airborne particulate matter

    NASA Astrophysics Data System (ADS)

    Thiodjio Sendja, Bridinette; Aquilanti, Giuliana; Vassura, Ivano; Giorgetti, Marco

    2016-05-01

    The study of elemental speciation in atmospheric particulate matter is important for the assessment of the source of the particle as well for the evaluation of its toxicity. XANES data at Fe, Ni, and Zn K-edges are recorded on a sample of urban dust (from the Rimini area of Emilia Romagna region, Italy) deposited on a filter and on the NIST standard reference material 1648. Using linear combination fitting we give an indication of the chemical species of the three metals present in the samples.

  5. High Frequency Properties of Ferrite/Fe-Si-Al Alloy Soft Magnetic Composites

    NASA Astrophysics Data System (ADS)

    Stergiou, Charalampos A.; Zaspalis, Vassilios

    The inclusion of Fe-Si-Al alloy particles in NiCuZn ferrite matrix was investigated with regard to the high frequency electromagnetic properties (complex permeability and permittivity). The resultant composites of relatively low density exhibit a shift of the permeability spectra to higher frequencies and an increase of dielectric polarization, which finally favour the electromagnetic wave attenuation at microwave frequencies. Thus, wider band return loss peaks are attained at frequencies above 6 GHz by thinner composite materials.

  6. Effects of metals Cu, Fe, Ni, V, and Zn on rat lung epithelial cells.

    PubMed

    Riley, Mark R; Boesewetter, Dianne E; Kim, Aana M; Sirvent, Francisco P

    2003-08-28

    Inhalation of combustion-derived particulate matter can have a variety of negative impacts on human health. Metals are known to play a substantial role in these effects, however, the interactions between cellular responses caused by multiple metals is not well understood. The impact of metals (Zn, Cu, Ni, V, and Fe) individually and in combination on a rat lung epithelial cell line (RLE-6TN) was evaluated. Quantifications involved measurement of inhibition of cell culture metabolism (mitochondrial succinate dehydrogenase activity), cell death, mechanisms of cell death, and cytokine secretion. The ranking of metal toxicity based on TC(50) values is V>Zn>Cu>Ni>Fe. Interactions were observed for exposures containing multiple metals: Zn+V, Zn+Cu, Zn+Fe, and Zn+Ni. Zn appears to diminish the negative impact of V and Cu; has an additive effect with Ni, and has no substantial effect on Fe toxicity. PMID:12927373

  7. Chemical ordering and large tunnel magnetoresistance in Co2FeAl/MgAl2O4/Co2FeAl(001) junctions

    NASA Astrophysics Data System (ADS)

    Scheike, Thomas; Sukegawa, Hiroaki; Inomata, Koichiro; Ohkubo, Tadakatsu; Hono, Kazuhiro; Mitani, Seiji

    2016-05-01

    Epitaxial magnetic tunnel junctions (MTJs) with a Co2FeAl/CoFe (0.5 nm)/MgAl2O4/Co2FeAl(001) structure were fabricated by magnetron sputtering. High-temperature in situ annealing led to a high degree of B2-order in the Co2FeAl layers and cation order of the MgAl2O4 barrier. Large tunnel magnetoresistance (TMR) of up to 342% was obtained at room temperature (616% at 4 K), in contrast to the TMR ratio ( ≲ 160%) suppressed by the band-folding effect in Fe/cation-ordered MgAl2O4/Fe MTJs. The present study reveals that the high degree of B2-order and the resulting high spin polarization in the Co2FeAl electrodes enable us to bypass the band-folding problem in spinel barriers.

  8. Effect of Zn Content on the Microstructure and Properties of Super-High Strength Al-Zn-Mg-Cu Alloys

    NASA Astrophysics Data System (ADS)

    Chen, Ziyong; Mo, Yuanke; Nie, Zuoren

    2013-08-01

    The microstructure and properties of three different Al-Zn-Mg-Cu alloys with high Zn content (9 wt pct, 10 wt pct, and 11 wt pct, marked as 9Zn, 10Zn, and 11Zn, respectively) were investigated. The strength of alloys increases as the Zn content increases from 9 wt pct to 10 wt pct, while it does not increase any more as the Zn content increases continuously from 10 wt pct to 11 wt pct. The stress-corrosion cracking (SCC) resistance decreases as the Zn content increases from 9 wt pct to 10 wt pct, while it changes unobviously as the Zn content increases continuously from 10 wt pct to 11 wt pct. The elongation and fracture toughness of alloys decrease as the Zn content increases in these Al-Zn-Mg-Cu alloys. The Zn content has little effect on the precipitation reaction of Al-Zn-Mg-Cu alloys that contain the mixture of GP zones, and η' are the main Matrix Precipitates (MPt) in the peak-aging state, and the mixture of η' and η are the main MPt in the over-aging state. The amount of MPt and coarse T (AlZnMgCu) phases are shown to increase with the increasing Zn content in Al-Zn-Mg-Cu alloys. The coarse T phases hardly dissolve into the matrix and are the source for the crack initiation, which may be the responsibility for the negative effect on the properties of high Zn content Al-Zn-Mg-Cu alloys.

  9. High-energy room-temperature Fe2+:ZnS laser

    NASA Astrophysics Data System (ADS)

    Firsov, K. N.; Gavrishchuk, E. M.; Ikonnikov, V. B.; Kazantsev, S. Yu; Kononov, I. G.; Rodin, S. A.; Savin, D. V.; Timofeeva, N. A.

    2016-01-01

    Characteristics of a room temperature laser on polycrystalline ZnS:Fe2+ subjected to diffuse doping from two sides were investigated. The sample was pumped by a non-chain electrodischarge HF laser with the FWHM duration of the radiation pulse of ~140 ns. The diameter of the pumping radiation spot on the surface of the crystal was 3.8 mm. Further increases in the size of the pumping spot were limited by parasitic generation arising due to a high concentration of Fe ions in the near-surface layer of the sample at a relatively small depth of doping (short length of active medium). The generation energy of 25.5 mJ was obtained at a slope efficiency of 12% with respect to the energy incident on the sample. Characteristics of lasers on polycrystalline ZnS:Fe2+ and ZnSe:Fe2+ have been compared in equal pumping conditions. The slope efficiencies of ZnSe:Fe2+ and ZnS:Fe2+ lasers with respect to the absorbed energy were 34% and 20%, respectively. At equal pumping energy absorbed in the samples, the duration of the ZnSe:Fe2+ laser radiation pulse was longer than that of the ZnS:Fe2+ laser. Possibilities of increasing the efficiency of ZnS:Fe2+ laser operation at room temperature by improving the technology of sample manufacturing and reducing the duration of the pumping pulse are discussed in this letter.

  10. Thermoelasticity of Al3+- and Fe3+-bearing bridgemanite

    NASA Astrophysics Data System (ADS)

    Valencia-Cardona, Juan; Shukla, Gaurav; Cococcioni, Matteo; Wentzcovitch, Renata

    2015-03-01

    We present quasi-harmonic LDA+U calculations of thermoelastic properties of Fe3+- and Al3+-bearing bridgemanite (MgSiO3), the main Earth forming phase, at relevant P,T conditions and compositions. Three charge-coupled substitutions, namely, Al3+-Al3+, Fe3+-Fe3+, and Fe3+-Al3+ have been investigated. Aggregate elastic moduli and sound velocities are successfully compared with limited experimental measurements available. The effect of the pressure induced high-spin to low-spin state change in Fe3+ in the B-site has been investigated in great detail since it has potentially dramatic effects on seismic velocities in the Earth's lower mantle. Research supported by NSF/EAR and NSF/CAREER.

  11. Synthesis and characterization of Al-Zn/Al2O3 nano-powder composites.

    PubMed

    Durai, T G; Das, Karabi; Das, Siddhartha

    2007-06-01

    Composites consisting of Al-Zn/Al2O3 have been synthesized using high energy mechanical milling. High energy ball milling increases the sintering rate of the composite powder due to increased diffusion rate. Owing to the finer microstructure, the hardness of the sintered composite produced by using the mechanically milled nanocomposite powder is significantly higher than that of the sintered composite produced by using the as-mixed powder. The mean crystallite size of the matrix has been determined to be 27 nm by Scherrer equation using X-ray diffraction data. The powders have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and differential thermal analysis (DTA). The effect of high-energy ball milling and subsequent annealing on a mixture of Al and ZnO has also been investigated. DTA result show that the reaction temperature of Al-ZnO decreases with the increase in the ball milling time. PMID:17654976

  12. Zn, Fe and S isotope fractionation in a large hydrothermal system

    NASA Astrophysics Data System (ADS)

    Gagnevin, D.; Boyce, A. J.; Barrie, C. D.; Menuge, J. F.; Blakeman, R. J.

    2012-07-01

    The genesis of hydrothermal ore deposits is of crucial economic importance. This study investigates the extent, causes and consequences of zinc and iron isotope fractionation in a large hydrothermal system at the world-class Navan Zn-Pb orebody, Ireland. Large variations in Zn, Fe and S isotope compositions have been measured in microdrilled sphalerite (ZnS) at the millimetre scale. δ66Zn and δ56Fe display a well-defined positive correlation and both also correlate with δ34S. These relationships represent the combined effects of kinetic Zn and Fe isotope fractionation during sphalerite precipitation, and S isotope variation through mixing of hot, metal-rich hydrothermal fluids and cool, bacteriogenic sulfide-bearing brines. Combined with S isotope data, δ56Fe and δ66Zn data on mine concentrates confirm that hydrothermal sulfide is a minor component of the overall deposit signature. Our data suggest that incoming pulses of metal-rich hydrothermal fluid triggered sulfide mineralisation, and that rapid precipitation of sphalerite from hydrothermal fluids will lead to strong kinetic fractionation of Zn and Fe isotopes at very short time and length scales, thereby limiting the use of Fe and Zn isotopes as exploration tools within deposits, but revealing the possibility of detecting new deposits from isotopically heavy Zn-Fe geochemical halos.

  13. Strength anomaly in B2 FeAl single crystals

    SciTech Connect

    Yoshimi, K.; Hanada, S.; Yoo, M.H.; Matsumoto, N.

    1994-12-31

    Strength and deformation microstructure of B2 Fe-39 and 48%Al single crystals (composition given in atomic percent), which were fully annealed to remove frozen-in vacancies, have been investigated at temperatures between room temperature and 1073K. The hardness of as-homogenized Fe-48Al is higher than that of as-homogenized Fe-39Al while after additional annealing at 698K the hardness of Fe-48Al becomes lower than that of Fe-39Al. Fe-39Al single crystals slowly cooled after homogenizing at a high temperature were deformed in compression as a function of temperature and crystal orientation. A peak of yield strength appears around 0.5T{sub m} (T{sub m} = melting temperature). The orientation dependence of the critical resolved shear stress does not obey Schmid`s law even at room temperature and is quite different from that of b.c.c. metals and B2 intermetallics at low temperatures. At the peak temperature slip transition from <111>-type to <001>-type is found to occur macroscopically and microscopically, while it is observed in TEM that some of the [111] dislocations decompose into [101] and [010] on the (1096I) plane below the peak temperature. The physical sources for the positive temperature dependence of yield stress of B2 FeAl are discussed based on the obtained results.

  14. Fabric cutting application of FeAl-based alloys

    SciTech Connect

    Sikka, V.K.; Blue, C.A.; Sklad, S.P.; Deevi, S.C.; Shih, H.R.

    1998-11-01

    Four intermetallic-based alloys were evaluated for cutting blade applications. These alloys included Fe{sub 3}Al-based (FAS-II and FA-129), FeAl-based (PM-60), and Ni{sub 3}Al-based (IC-50). These alloys were of interest because of their much higher work-hardening rates than the conventionally used carbon and stainless steels. The FeAl-based PM-60 alloy was of further interest because of its hardening possibility through retention of vacancies. The vacancy retention treatment is much simpler than the heat treatments used for hardening of steel blades. Blades of four intermetallic alloys and commercially used M2 tool steel blades were evaluated under identical conditions to cut two-ply heavy paper. Comparative results under identical conditions revealed that the FeAl-based alloy PM-60 outperformed the other intermetallic alloys and was equal to or somewhat better than the commercially used M2 tool steel.

  15. Oxidation behavior of FeAl+Hf,Zr,B

    NASA Technical Reports Server (NTRS)

    Smialek, James L.; Doychak, Joseph

    1988-01-01

    The oxidation behavior of Fe-40Al-1Hf, Fe-40Al-1Hf-0.4B, and Fe-40Al-0.1Zr-0.4B (at. percent) alloys was characterized after 900, 1000, and 100 C exposures. Isothermal tests revealed parabolic kinetics after a period of transitional theta-alumina scale growth. The parabolic growth rates for the subsequent alpha-alumina scales were about five times higher than those for NiAl+0.1Zr alloys. The isothermally grown scales showed a propensity toward massive scale spallation due to both extensive rumpling from growth stresses and to an inner layer of HfO2. Cyclic oxidation for 200 1-hr cycles produced little degradation at 900 or 1000 C, but caused significant spallation at 1100 C in the form of small segments of the outer scale. The major difference in the cyclic oxidation of the three FeAl alloys was increased initial spallation for FeAl+Zr,B. Although these FeAl alloys showed many similarities to NiAl alloys, they were generally less oxidation resistant. It is believed that this resulted from nonoptimal levels of dopants and larger thermal expansion mismatch stresses.

  16. Oxidation of Fe-Cr-Al and Fe-Cr-Al-Y Single Crystals

    NASA Astrophysics Data System (ADS)

    Grabke, H. J.; Siegers, M.; Tolpygo, V. K.

    1995-03-01

    Single crystal samples of the alloy Fe-20%Cr-5%Al with and without Y-doping were used to study the "reactive element" (RE) effect, which causes improved oxidation behaviour and formation of a protective Al2O3 layer on this alloy. The oxidation was followed by AES at 10-7 mbar O2 up to about 1000 °C. Most observations were peculiar for this low pO2 environment, but yttrium clearly favors the formation of Al-oxide and stabilizes it also under these conditions, probably by favoring its nucleation. The oxides formed are surface compounds of about monolayer thickness, not clearly related to bulk oxides. Furthermore, the morphologies of oxide scales were investigated by SEM, after oxidation at 1000°C for 100 h at 133 mbar O2. On Fe-Cr-Al the scale is strongly convoluted and tends to spalling, whereas the presence of Y leads to flat scales which are well adherent. This difference is explained by a change in growth mechanism. The tendency for separation of oxide and metal was highest for the samples with low energy metal surface, i.e. (100) and (110), the scale was better adherent on the (111) oriented surface and on the polycrystalline specimen, since in the latter cases the overall energy for scale/metal separation is higher. All observations, from the low and from the high pO2 experiments, are discussed in relation to the approximately ten mechanisms proposed in the literature for explanation of the RE effects.

  17. Zn-Site Determination in Protein Encapsulated ZnxFe3-xO4 Nanoparticles

    SciTech Connect

    Pool, V. L.; Klem, M. T.; Holroyd, J.; Harris, T.; Arenholz, E.; Young, M.; Douglas, T.; Idzerda, Y. U.

    2008-10-01

    The X-ray absorption spectra of the Fe and Zn L-edges for 6.7 nm Fe{sub 3}O{sub 4} nanoparticles grown inside 12 nm ferritin protein cages with 10%, 15%, 20% and 33% zinc doping, shows that the Zn is substitutional as Zn{sup 2+} within the iron oxide host structure. A Neel-Arrhenius plot of the blocking temperature in the frequency dependent ac-susceptibility measurements show that the particles are non-interacting and that the anisotropy energy barrier is reduced with Zn loading. X-ray magnetic circular dichroism (XMCD) of the Fe displays a linear decrease with Zn-doping in sharp contrast to the initial increase present in the bulk system. The most plausible explanation for the moment decrease is that Zn substitutes preferentially into the tetrahedral A-site as a Zn{sup 2+} cation, generating a mixed spinel.

  18. Third generation biosensing matrix based on Fe-implanted ZnO thin film

    NASA Astrophysics Data System (ADS)

    Saha, Shibu; Gupta, Vinay; Sreenivas, K.; Tan, H. H.; Jagadish, C.

    2010-09-01

    Third generation biosensor based on Fe-implanted ZnO (Fe-ZnO) thin film has been demonstrated. Implantation of Fe in rf-sputtered ZnO thin film introduces redox center along with shallow donor level and thereby enhance its electron transfer property. Glucose oxidase (GOx), chosen as model enzyme, has been immobilized on the surface of the matrix. Cyclic voltammetry and photometric assay show that the prepared bioelectrode, GOx/Fe-ZnO/ITO/Glass is sensitive to the glucose concentration with enhanced response of 0.326 μA mM-1 cm-2 and low Km of 2.76 mM. The results show promising application of Fe-implanted ZnO thin film as an attractive matrix for third generation biosensing.

  19. Nonisothermal kinetics study of phase evolution of Zn-Fe intermetallics

    SciTech Connect

    Uwakweh, O.N.C.; Liu, Z.T.; Boisson, M.

    1996-12-31

    Through mechanical alloying of pure elemental powders of Fe and Zn, true homogeneous alloys of {Gamma} (Fe{sub 3}Zn{sub 10}), {Gamma}{sub 1} (Fe{sub 5}Zn{sub 21}), {delta} (FeZn{sub 7}) and {zeta} (FeZn{sub 13}) intermetallic phases are formed. Based on nonisothermal kinetics analyses, the highest activation energies associated with the metastable to stable transformations of these phases are determined as follows: 170 {+-} 1 kJ/mol, 251 {+-} 2 kJ/mol, 176 {+-} 1 kJ/mol and 737 {+-} 4 kJ/mol for the {Gamma}, {Gamma}{sub 1}, {delta} and {zeta}-phases, respectively. These values reflect different diffusion/thermally induced processes associated with the transition of each of these phases.

  20. Third generation biosensing matrix based on Fe-implanted ZnO thin film

    SciTech Connect

    Saha, Shibu; Gupta, Vinay; Sreenivas, K.; Tan, H. H.; Jagadish, C.

    2010-09-27

    Third generation biosensor based on Fe-implanted ZnO (Fe-ZnO) thin film has been demonstrated. Implantation of Fe in rf-sputtered ZnO thin film introduces redox center along with shallow donor level and thereby enhance its electron transfer property. Glucose oxidase (GOx), chosen as model enzyme, has been immobilized on the surface of the matrix. Cyclic voltammetry and photometric assay show that the prepared bioelectrode, GOx/Fe-ZnO/ITO/Glass is sensitive to the glucose concentration with enhanced response of 0.326 {mu}A mM{sup -1} cm{sup -2} and low Km of 2.76 mM. The results show promising application of Fe-implanted ZnO thin film as an attractive matrix for third generation biosensing.

  1. Semiconducting properties of Al doped ZnO thin films.

    PubMed

    Al-Ghamdi, Ahmed A; Al-Hartomy, Omar A; El Okr, M; Nawar, A M; El-Gazzar, S; El-Tantawy, Farid; Yakuphanoglu, F

    2014-10-15

    Aluminum doped ZnO (AZO) thin films were successfully deposited via spin coating technique onto glass substrates. Structural properties of the films were analyzed by X-ray diffraction, atomic force microscopy (AFM) and energy dispersive X-ray spectroscopy. X-ray diffraction results reveal that all the films are polycrystalline with a hexagonal wurtzite structure with a preferential orientation according to the direction (002) plane. The crystallite size of ZnO and AZO films was determined from Scherrer's formula and Williamson-Hall analysis. The lattice parameters of the AZO films were found to decrease with increasing Al content. Energy dispersive spectroscopy (EDX) results indicate that Zn, Al and O elements are present in the AZO thin films. The electrical conductivity, mobility carriers and carrier concentration of the films are increased with increasing Al doping concentration. The optical band gap (Eg) of the films is increased with increasing Al concentration. The AZO thin films indicate a high transparency in the visible region with an average value of 86%. These transparent AZO films may be open a new avenue for optoelectronic and photonic devices applications in near future. PMID:24840493

  2. The Charpy impact behavior of Fe{sub 3}Al and Fe{sub 3}Al-20 at % Mn alloys

    SciTech Connect

    Liu, J.N.; Yan, W.; Ma, J.L.; Wu, K.H.

    1997-12-31

    A series of experiments were conducted to investigate the impact fracture behavior of Fe{sub 3}Al and Fe{sub 3}Al-20 Mn alloys. The results of this study indicated that: (i) The addition of Mn introduces an ordered L1{sub 2}-type phase in the Fe{sub 3}Al-based alloys. On the other hand, the addition of Mn decreases the order parameter of the DO{sub 3} {alpha} phase. (ii) The total-impact energy of an Fe{sub 3}Al alloy increases with the temperature at the low-temperature range (<600 C), then drops around 700 C, and finally increases again as the temperature further elevates. (iii) The trend of the variation of the impact energy of Fe{sub 3}Al-20 at % Mn alloy with temperature is the same as that of the Fe{sub 3}Al alloy. (iv) And the addition of Mn significantly improves the impact energy of the Fe{sub 3}Al-based alloy, and changes the variation of the crack-growth energy with the testing temperature when the temperature is above 700 C.

  3. Microstructure Evolution of Atomized Al-0.61 wt pct Fe and Al-1.90 wt pct Fe Alloys

    NASA Astrophysics Data System (ADS)

    Chen, Jian; Dahlborg, Ulf; Bao, Cui Min; Calvo-Dahlborg, Monique; Henein, Hani

    2011-06-01

    The microstructure evolution of impulse atomized powders of Al-0.61 wt pct and Al-1.90 wt pct Fe compositions have been investigated with a scanning electron microscope, transmission electron microscope, neutron diffraction, and backscattering electron diffraction (EBSD). Both hypoeutectic and hypereutectic compositions demonstrated similar macrostructure ( i.e., primary α-Al dendrites/cells with eutectic Al-Fe intermetallics decorated at the dendritic/cellular walls). Selected area electron diffraction (SAED) analysis and SAED pattern simulation identified the eutectic Al-Fe intermetallic as AlmFe ( m = 4.0-4.4). This is verified by neutron diffraction analysis. Cubic texture was observed by EBSD on the droplets with dendritic growth direction close to <111>. The possible reasons are discussed.

  4. Implications of Zn/Fe ratios for the sources of Colorado Plateau basalts

    NASA Astrophysics Data System (ADS)

    Rudzitis, S.; Reid, M. R.

    2011-12-01

    Early Miocene to recent mafic magmatism migrated across the Arizona Transition Zone towards the center of the stable Colorado Plateau at a rate of ~ 3-6 km/Myr (Roy et al., 2009). Present-day volcanic centers are close to a stepwise change in the thickness of the lithosphere between the Colorado Plateau and Basin and Range. Accordingly, volcanic migration might track progressive thinning of the lithosphere towards the center of the Colorado Plateau. This project aims to determine the conditions of melt generation across the transition zone in order to investigate the temporal/spatial correlation between volcanism and thinning of the Colorado Plateau lithosphere. Pressure and temperature estimates for Colorado Plateau basalts can be obtained from the Mg and Si contents of melts (Lee et al, 2009) but require melting of a peridotitic source. Eclogite and pyroxenite xenoliths reported in Colorado Plateau basalts show that melt sources could be olivine-poor. Zn/Fe ratios in melts can help to distinguish contributions from olivine-poor sources because they are sensitive to differences in bulk chemistry and to mineralogy (Le Roux et al., 2010). Specifically, Zn/Fe is not fractionated between melt, olivine, and orthopyroxene, but is highly fractionated when clinopyroxene and garnet are present. Our work to date has focused on laser ablation-IC-PMS analysis of individual olivine grains from high-Mg basalts (>8.0 wt. %) from the San Francisco and Mormon Mountain volcanic fields. Preliminary values of Zn/Fe ratios that represent the averages of multiple analyses of several grains in individual samples range from 7.9 to 9.3 (x10000). Variations of up to 1.7 (x10000) in the ratios exist between individual grains within samples and could be the result of co-crystallization of clinopyroxene with olivine. The lowest values in each sample should approach the Zn/Fe ratios of parental melts, and are, in turn, similar to MORB values and predicted peridotite melts. The results suggest

  5. Aqueous synthesis and enhanced photocatalytic activity of ZnO/Fe2O3 heterostructures

    NASA Astrophysics Data System (ADS)

    Achouri, Faouzi; Corbel, Serge; Aboulaich, Abdelhay; Balan, Lavinia; Ghrabi, Ahmed; Ben Said, Myriam; Schneider, Raphaël

    2014-10-01

    We report a facile synthesis of ZnO/Fe2O3 heterostructures based on the hydrolysis of FeCl3 in the presence of ZnO nanoparticles. The material structure, composition, and its optical properties have been examined by means of transmission electron microscopy, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and diffuse reflectance UV-visible spectroscopy. Results obtained show that 2.9 nm-sized Fe2O3 nanoparticles produced assemble with ZnO to form ZnO/Fe2O3 heterostructures. We have evaluated the photodegradation performances of ZnO/Fe2O3 materials using salicylic acid under UV-light. ZnO/Fe2O3 heterostructures exhibited enhanced photocatalytic capabilities than commercial ZnO due to the effective electron/hole separation at the interfaces of ZnO/Fe2O3 allowing the enhanced hydroxyl and superoxide radicals production from the heterostructure.

  6. Paramagnetism and antiferromagnetic interactions in single-phase Fe-implanted ZnO.

    PubMed

    Pereira, L M C; Wahl, U; Correia, J G; Van Bael, M J; Temst, K; Vantomme, A; Araújo, J P

    2013-10-16

    As the intrinsic origin of the high-temperature ferromagnetism often observed in wide-gap dilute magnetic semiconductors becomes increasingly debated, there is a growing need for comprehensive studies on the single-phase region of the phase diagram of these materials. Here we report on the magnetic and structural properties of Fe-doped ZnO prepared by ion implantation of ZnO single crystals. A detailed structural characterization shows that the Fe impurities substitute for Zn in ZnO in a wurtzite Zn(1-x)Fe(x)O phase which is coherent with the ZnO host. In addition, the density of beam-induced defects is progressively decreased by thermal annealing up to 900 ° C, from highly disordered after implantation to highly crystalline upon subsequent annealing. Based on a detailed analysis of the magnetometry data, we demonstrate that isolated Fe impurities occupying Zn-substitutional sites behave as localized paramagnetic moments down to 2 K, irrespective of the Fe concentration and the density of beam-induced defects. With increasing local concentration of Zn-substitutional Fe, strong nearest-cation-neighbor antiferromagnetic interactions favor the antiparallel alignment of the Fe moments. PMID:24025311

  7. Structural, optical, hyperfine and magnetization studies of ZnO encapsulated α-Fe nanoparticles

    SciTech Connect

    Rathore, A.K.; Pati, S.P.; Roychowdhury, A.; Das, D.

    2014-12-15

    We report the successful preparation and characterization of magnetic-fluorescent nanoparticles (NPs) by overcoming the difficulty of handling α-Fe nanoparticles that are less stable and have high affinity to get oxidized in air even at room temperature. Nanocrystalline α-Fe particles embedded by ZnO have been synthesized by a two step chemical route. Concentration of α-Fe has been varied as 15, 30 and 50 wt% of the sample. Detailed investigations on structural, hyperfine, optical and magnetic characteristics have been carried out. X-ray diffraction, transmission electron microscopy and fourier transform infrared spectroscopy studies have been used to confirm the coexistence of Fe and ZnO phases in the nanocomposites (NCs). The presence of α-Fe is also confirmed by Mössbauer spectroscopy. However, other forms of iron are also detected in the sample. UV–vis spectrum of nanocomposites shows a red shift with respect to the pristine ZnO which is attributed to the electron transfer between Fe and ZnO that provides support to the formation of the Fe- ZnO NC. The photoluminescence (PL) spectra of Fe-ZnO nanocomposites exhibit blue shift of the UV and weaker visible emission lines compared to the pristine ZnO. Nanocomposites are found to be magnetically soft having high saturation magnetization with very low remanence. Low temperature coercivity enhancement due to freezing of uncompensated surface spins is also found in all samples.

  8. Nanostructured Al-ZnO/CdSe/Cu2O ETA solar cells on Al-ZnO film/quartz glass templates

    PubMed Central

    2011-01-01

    The quartz/Al-ZnO film/nanostructured Al-ZnO/CdSe/Cu2O extremely thin absorber solar cell has been successfully realized. The Al-doped ZnO one-dimensional nanostructures on quartz templates covered by a sputtering Al-doped ZnO film was used as the n-type electrode. A 19- to 35-nm-thin layer of CdSe absorber was deposited by radio frequency magnetron sputtering, coating the ZnO nanostructures. The voids between the Al-ZnO/CdSe nanostructures were filled with p-type Cu2O, and therefore, the entire assembly formed a p-i-n junction. The cell shows the energy conversion efficiency as high as 3.16%, which is an interesting option for developing new solar cell devices. PACS: 88.40.jp; 73.40.Lq; 73.50.Pz. PMID:22136081

  9. Nanostructured Al-ZnO/CdSe/Cu2O ETA solar cells on Al-ZnO film/quartz glass templates.

    PubMed

    Wang, Xianghu; Li, Rongbin; Fan, Donghua

    2011-01-01

    The quartz/Al-ZnO film/nanostructured Al-ZnO/CdSe/Cu2O extremely thin absorber solar cell has been successfully realized. The Al-doped ZnO one-dimensional nanostructures on quartz templates covered by a sputtering Al-doped ZnO film was used as the n-type electrode. A 19- to 35-nm-thin layer of CdSe absorber was deposited by radio frequency magnetron sputtering, coating the ZnO nanostructures. The voids between the Al-ZnO/CdSe nanostructures were filled with p-type Cu2O, and therefore, the entire assembly formed a p-i-n junction. The cell shows the energy conversion efficiency as high as 3.16%, which is an interesting option for developing new solar cell devices.PACS: 88.40.jp; 73.40.Lq; 73.50.Pz. PMID:22136081

  10. Nanostructured Al-ZnO/CdSe/Cu2O ETA solar cells on Al-ZnO film/quartz glass templates

    NASA Astrophysics Data System (ADS)

    Wang, Xianghu; Li, Rongbin; Fan, Donghua

    2011-12-01

    The quartz/Al-ZnO film/nanostructured Al-ZnO/CdSe/Cu2O extremely thin absorber solar cell has been successfully realized. The Al-doped ZnO one-dimensional nanostructures on quartz templates covered by a sputtering Al-doped ZnO film was used as the n-type electrode. A 19- to 35-nm-thin layer of CdSe absorber was deposited by radio frequency magnetron sputtering, coating the ZnO nanostructures. The voids between the Al-ZnO/CdSe nanostructures were filled with p-type Cu2O, and therefore, the entire assembly formed a p-i-n junction. The cell shows the energy conversion efficiency as high as 3.16%, which is an interesting option for developing new solar cell devices. PACS: 88.40.jp; 73.40.Lq; 73.50.Pz.

  11. Methotrexate intercalated ZnAl-layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Chakraborty, Manjusha; Dasgupta, Sudip; Soundrapandian, Chidambaram; Chakraborty, Jui; Ghosh, Swapankumar; Mitra, Manoj K.; Basu, Debabrata

    2011-09-01

    The anticancerous drug methotrexate (MTX) has been intercalated into an ZnAl-layered double hydroxide (LDH) using an anion exchange technique to produce LDH-MTX hybrids having particle sizes in the range of 100-300 nm. X-ray diffraction studies revealed increases in the basal spacings of ZnAl-LDH-MTX hybrid on MTX intercalation. This was corroborated by the transmission electron micrographs, which showed an increase in average interlayer spacing from 8.9 Å in pristine LDH to 21.3 Å in LDH-MTX hybrid. Thermogravimetric analyses showed an increase in the decomposition temperature for the MTX molecule in the LDH-MTX hybrid indicating enhanced thermal stability of the drug molecule in the LDH nanovehicle. The cumulative release profile of MTX from ZnAl-LDH-MTX hybrids in phosphate buffer saline (PBS) at pH 7.4 was successfully sustained for 48 h following Rigter-Peppas model release kinetics via diffusion.

  12. Pharmocokinetical study of Al- and Zn-sulphonated phthalocyanines

    NASA Astrophysics Data System (ADS)

    Kazachkina, Natalia I.; Zharkova, Natalia N.; Fomina, Galina I.; Yakubovskaya, Raisa I.; Sokolov, Victor V.; Lukyanets, Eugeny A.

    1996-12-01

    The comparative pharmacokinetical study of Al- and Zn- sulphonated phthalocyanines (AlPcS and ZnPcS, respectively) is the aim of the present work. Mice bearing solid Ehrlich tumor were used in this study. AlPcS (sodium salt) and ZnPcS (ammonium and sodium salts were used as photosensitizers. The photosensitizers were injected i/v in various doses. The exogenous fluorescence of tissues (tumor, liver, spleen, kidneys, muscles, skin) was measured dynamically after sensitization. It was shown that all of the photosensitizers under study had similar distribution pattern in organisms of mice and were selectively accumulated in the Ehrlich tumor tissue. The exogenous fluorescence intensity of tissues and it tumor:normal muscle ratio (Cs) depended on the dosage of the preparation, on the time, which had passed after drug injection, and on the stage of tumor growth. It was also shown that the kinetics of the tissue uptake of the studied sensitizers varied to some extent. Thus, the obtained data may be interesting for deeper understanding of the interaction of the dye with malignant tissues.

  13. Observations of Al, Fe and Ca(+) in Mercury's Exosphere

    NASA Technical Reports Server (NTRS)

    Bida, Thomas A.; Killen, Rosemary M.

    2011-01-01

    We report 5-(sigma) tangent column detections of Al and Fe, and strict 3-(sigma) tangent column upper limits for Ca(+) in Mercury's exosphere obtained using the HIRES spectrometer on the Keck I telescope. These are the first direct detections of Al and Fe in Mercury's exosphere. Our Ca(-) observation is consistent with that reported by The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft.

  14. Electrical and optical properties of Al-doped ZnO and ZnAl2O4 films prepared by atomic layer deposition

    PubMed Central

    2013-01-01

    ZnO/Al2O3 multilayers were prepared by alternating atomic layer deposition (ALD) at 150°C using diethylzinc, trimethylaluminum, and water. The growth process, crystallinity, and electrical and optical properties of the multilayers were studied with a variety of the cycle ratios of ZnO and Al2O3 sublayers. Transparent conductive Al-doped ZnO films were prepared with the minimum resistivity of 2.4 × 10−3 Ω·cm at a low Al doping concentration of 2.26%. Photoluminescence spectroscopy in conjunction with X-ray diffraction analysis revealed that the thickness of ZnO sublayers plays an important role on the priority for selective crystallization of ZnAl2O4 and ZnO phases during high-temperature annealing ZnO/Al2O3 multilayers. It was found that pure ZnAl2O4 film was synthesized by annealing the specific composite film containing alternative monocycle of ZnO and Al2O3 sublayers, which could only be deposited precisely by utilizing ALD technology. PMID:23537274

  15. Alloy development and processing of FeAl: An overview

    SciTech Connect

    Maziasz, P.J.; Goodwin, G.M.; Alexander, D.J.; Viswanathan, S.

    1997-03-01

    In the last few years, considerable progress has been made in developing B2-phase FeAl alloys with improved weldability, room-temperature ductility, and high-temperature strength. Controlling the processing-induced microstructure is also important, particularly for minimizing trade-offs in various properties. FeAl alloys have outstanding resistance to high-temperature oxidation, sulfidation, and corrosion in various kinds of molten salts due to formation of protective Al{sub 2}O{sub 3} scales. Recent work shows that FeAl alloys are carburization-resistant as well. Alloys with 36 to 40 at. % Al have the best combination of corrosion resistance and mechanical properties. Minor alloying additions of Mo, Zr, and C, together with microalloying additions of B, produce the best combination of weldability and mechanical behavior. Cast FeAl alloys, with 200 to 400 {mu}m grain size and finely dispersed ZrC, have 2 to 5% tensile ductility in air at room-temperature, and a yield strength > 400 MPa up to about 700 to 750{degrees}C. Extruded ingot metallurgy (I/M) and powder metallurgy (P/M) materials with refined grain sizes ranging from 2 to 50 {mu}m, can have 10 to 15% ductility in air and be much stronger, and can even be quite tough, with Charpy impact energies ranging from 25 to 105 J at room-temperature. This paper highlights progress made in refining the alloy composition and exploring processing effects on FeAl for monolithic applications. It also includes recent progress on developing FeAl weld-overlay technology, and new results on welding of FeAl alloys. It summarizes some of the current industrial testing and interest for applications.

  16. Improved photoluminescence property of CTAB assisted polyaniline-AlZnO nanocomposite

    NASA Astrophysics Data System (ADS)

    Mitra, Mousumi; Kargupta, Kajari; Ganguly, Saibal; Banerjee, Dipali

    2015-06-01

    Polyaniline-Al doped ZnO ((PANI-AlZnO:: 70:30) nanocomposite was prepared via in situ chemical oxidative polymerization, while the hexagonal powder of AlZnO was synthesized via sol-gel technique, using Hexadecyltrimethylammonium bromide (CTAB) as a capping agent. The prepared nanocomposite was characterized by High resolution transmission electron microscopy (HRTEM), EDAX, X-ray diffraction (XRD) and Fourier transforms infrared (FTIR) spectra. The optical property of the nanomaterials is examined by photoluminescence (PL) spectra analysis. The XRD pattern confirms the formation of Al doped ZnO as well as PANI. The HRTEM images of the composite showed the formation of hexagonal AlZnO embedded in polyaniline matrix. EDAX spectrum shows the compositional analysis of the nanocomposite. FTIR spectra confirm the formation of nanocomposite of PANI and hexagonal AlZnO. The PL intensity of the nanocomposite is improved as compared to pure AlZnO.

  17. Improved photoluminescence property of CTAB assisted polyaniline-AlZnO nanocomposite

    SciTech Connect

    Mitra, Mousumi; Banerjee, Dipali; Kargupta, Kajari; Ganguly, Saibal

    2015-06-24

    Polyaniline-Al doped ZnO ((PANI-AlZnO:: 70:30) nanocomposite was prepared via in situ chemical oxidative polymerization, while the hexagonal powder of AlZnO was synthesized via sol-gel technique, using Hexadecyltrimethylammonium bromide (CTAB) as a capping agent. The prepared nanocomposite was characterized by High resolution transmission electron microscopy (HRTEM), EDAX, X-ray diffraction (XRD) and Fourier transforms infrared (FTIR) spectra. The optical property of the nanomaterials is examined by photoluminescence (PL) spectra analysis. The XRD pattern confirms the formation of Al doped ZnO as well as PANI. The HRTEM images of the composite showed the formation of hexagonal AlZnO embedded in polyaniline matrix. EDAX spectrum shows the compositional analysis of the nanocomposite. FTIR spectra confirm the formation of nanocomposite of PANI and hexagonal AlZnO. The PL intensity of the nanocomposite is improved as compared to pure AlZnO.

  18. Multiferroicity in ZnO nanodumbbell/BiFeO3 nanoparticle heterostructures

    NASA Astrophysics Data System (ADS)

    Mahesh, Dabbugalla; Mandal, Swapan K.

    2016-04-01

    We report here on the multiferroic properties of ZnO-BiFeO3 (BiFeO3 referred hereinafter as BFO) nanocomposite structures obtained by using a facile solution-based synthesis route. ZnO is found to grow in the form of well-crystallized and self-assembled dumbbell-like structures. BFO nanoparticles (NPs) are deposited onto ZnO nanodumbbells (NDs) to obtain ZnO-BFO heterostructures. The nanocomposites show prominent ferroelectric polarization hysteresis loop along with enhanced magnetization in comparison to pure BFO NPs. The ordered alignment of spins along with the suppression of Fe-O-Fe antiferromagnetic super-exchange interactions at the ZnO/BFO interface plausibly gives rise to observed multiferroic properties.

  19. Vibration DOS of 57Fe and Zn doped rutile Sn(Sb) oxides

    NASA Astrophysics Data System (ADS)

    Nomura, Kiyoshi; Rykov, Alexandre; Németh, Zoltán; Yoda, Yoshitaka

    2012-03-01

    Sn oxides co-doped with Zn, Sb and 57Fe were prepared by sol-gel method, and especially the doping effect of non-magnetic Zn ions was studied. The bulk saturation magnetization is in accordance with the intensity of the magnetic component in Mössbauer spectra. The nuclear inelastic scattering (NIS) spectra of these compounds were measured in SPring 8. The vibration density of states (VDOS) of 57Fe doped Sn(Sb) oxides showed that the softening peaks around 15-20 meV appeared by doping less than 10% Zn ions. The clusters of non-magnetic ZnFe2O4 may be most probably formed under the limit of XRD detections. The results suggest that the strengthening of ferromagnetism, which appears in the dilute Zn doping, may occur due to the spin arrangement of dilute Fe3 + through magnetic defects rather than the formation of magnetic iron oxides.

  20. Thermoelectric Transport Properties of Fe-Enriched ZnO with High-Temperature Nanostructure Refinement.

    PubMed

    Liang, Xin

    2015-04-22

    Thermoelectric properties of Fe-doped ZnO materials are investigated and correlated with the phase and microstructural evolution. Both a ZnO solid solution phase and a ZnFe2O4 spinel phase are observed. Analysis was made of temperature measurements of Seebeck coefficients as combined with the law of mixture to estimate the Fermi level in the constituent phases, which are further correlated with the Fe solute concentration in ZnO lattices and the overall electrical conductivity. In addition, the thermoelectric figure of merit is found to increase with the actual Fe content in ZnO lattices, due to the reduced thermal conductivity by point defect scattering of phonons and enhanced electrical transport via electron doping. The maximum achievable power factor of Fe-doped ZnO material is found to be similar to that of the ZnO-In2O3 system. Another important finding of the present work is the significant nanostructure refinement in 18 month old FeO1.5-doped ZnO after high-temperature thermal treatment, leading to further reduced thermal conductivity, which is beneficial and promising for high-temperature thermoelectric performance. PMID:25839985

  1. Paramagnetism and antiferromagnetic interactions in single-phase Fe-implanted ZnO

    NASA Astrophysics Data System (ADS)

    Pereira, L. M. C.; Wahl, U.; Correia, J. G.; Van Bael, M. J.; Temst, K.; Vantomme, A.; Araújo, J. P.

    2013-10-01

    As the intrinsic origin of the high-temperature ferromagnetism often observed in wide-gap dilute magnetic semiconductors becomes increasingly debated, there is a growing need for comprehensive studies on the single-phase region of the phase diagram of these materials. Here we report on the magnetic and structural properties of Fe-doped ZnO prepared by ion implantation of ZnO single crystals. A detailed structural characterization shows that the Fe impurities substitute for Zn in ZnO in a wurtzite Zn1-xFexO phase which is coherent with the ZnO host. In addition, the density of beam-induced defects is progressively decreased by thermal annealing up to 900 ° C, from highly disordered after implantation to highly crystalline upon subsequent annealing. Based on a detailed analysis of the magnetometry data, we demonstrate that isolated Fe impurities occupying Zn-substitutional sites behave as localized paramagnetic moments down to 2 K, irrespective of the Fe concentration and the density of beam-induced defects. With increasing local concentration of Zn-substitutional Fe, strong nearest-cation-neighbor antiferromagnetic interactions favor the antiparallel alignment of the Fe moments.

  2. In situ investigation of spinodal decomposition in hypermonotectic Al Bi and Al Bi Zn alloys

    NASA Astrophysics Data System (ADS)

    Schaffer, P. L.; Mathiesen, R. H.; Arnberg, L.; Di Sabatino, M.; Snigirev, A.

    2008-05-01

    Spinodal decomposition of hypermonotectic Al-6 wt.%Bi, Al-8 wt.%Bi and Al-6 wt.%Bi-8 wt.%Zn alloys has been investigated using synchrotron radiography. In the case of the 6 and 8 wt.%Bi binary alloys undercoolings of 70 and 110 K, respectively, were required to initiate the L→L1+L2 reaction, which appeared to occur very close to the monotectic reaction temperature. The nucleated L2 droplets were set in collective size-dependent motion by forces coupled to external fields (gravity and imposed temperature gradient) as well as forces arising due to internal fluctuations of the system. With experimental conditions similar to those realized during strip casting of the same materials, it was found that the size-dependant droplet velocity field combined with Stokes drag at the L1-L2 interfaces as well as attractive and repulsive diffusion-coupling between adjacent L2 droplets, yield complex meso- to microscale hydrodynamics. The hydrodynamics are the dominating mechanisms for L2 droplet coagulation, and are accordingly decisive for the final size distribution and geometrical dispersion of the soft Bi-rich component in the cast material. A different decomposition mode was observed in the Al-6 wt.%Bi-8 wt.%Zn ternary alloy, with the L2 droplets undergoing an immiscible-miscible-immiscible transition. In contrast to what was found for the binaries, L2 domains formed at relatively small undercoolings, and very little droplet motion was observed, as all L2 domains nucleated and remained on the crucible walls until they encroached on the monotectic front. At small distances from the monotectic front a Zn-rich solute boundary layer preceding the α-Al, caused the L2 domains to dissolve as Bi-Zn-Al regains complete miscibility upon reaching a critical Zn-concentration. In the shallow mush region behind the monotectic reaction, a high Zn solid solubility and a relatively fast diffusion of Zn in α-Al combine to cause a rapid diminishing Zn concentration in the mush liquid

  3. Oxidation Resistant Ti-Al-Fe Diffusion Barrier for FeCrAlY Coatings on Titanium Aluminides

    NASA Technical Reports Server (NTRS)

    Brady, Michael P. (Inventor); Smialke, James L. (Inventor); Brindley, William J. (Inventor)

    1996-01-01

    A diffusion barrier to help protect titanium aluminide alloys, including the coated alloys of the TiAl gamma + Ti3Al (alpha2) class, from oxidative attack and interstitial embrittlement at temperatures up to at least 1000 C is disclosed. The coating may comprise FeCrAlX alloys. The diffusion barrier comprises titanium, aluminum, and iron in the following approximate atomic percent: Ti-(50-55)Al-(9-20)Fe. This alloy is also suitable as an oxidative or structural coating for such substrates.

  4. Influence of FeCrAl Content on Microstructure and Bonding Strength of Plasma-Sprayed FeCrAl/Al2O3 Coatings

    NASA Astrophysics Data System (ADS)

    Zhou, Liang; Luo, Fa; Zhou, Wancheng; Zhu, Dongmei

    2016-02-01

    Low-power plasma-sprayed FeCrAl/Al2O3 composite coatings with 1.5 mm thickness have been fabricated for radar absorption applications. The effects of FeCrAl content on the coating properties were studied. The FeCrAl presents in the form of a few thin lamellae and numerous particles, demonstrating relatively even distribution in all the coatings. Results show that the micro-hardness and porosity decrease with the increase in FeCrAl content. With FeCrAl content increasing from 28 to 47 wt.%, the bonding strength of the coatings with 1.5 mm thickness increases from 10.5 to 27 MPa, and the failure modes are composed of cohesive and adhesive failure, which are ascribed to the coating microstructure and the residual stress, respectively.

  5. Room temperature ferromagnetism in undoped and Fe doped ZnO nanorods: Microwave-assisted synthesis

    SciTech Connect

    Limaye, Mukta V.; Singh, Shashi B.; Das, Raja; Poddar, Pankaj; Kulkarni, Sulabha K.

    2011-02-15

    One-dimensional (1D) undoped and Fe doped ZnO nanorods of average length {approx}1 {mu}m and diameter {approx}50 nm have been obtained using a microwave-assisted synthesis. The magnetization (M) and coercivity (H{sub c}) value obtained for undoped ZnO nanorods at room temperature is {approx}5x10{sup -3} emu/g and {approx}150 Oe, respectively. The Fe doped ZnO samples show significant changes in M -H loop with increasing doping concentration. Both undoped and Fe doped ZnO nanorods exhibit a Curie transition temperature (T{sub c}) above 390 K. Electron spin resonance and Moessbauer spectra indicate the presence of ferric ions. The origin of ferromagnetism in undoped ZnO nanorods is attributed to localized electron spin moments resulting from surface defects/vacancies, where as in Fe doped samples is explained by F center exchange mechanism. -- Graphical abstract: Room temperature ferromagnetism has been reported in undoped and Fe doped ZnO nanorods of average length {approx}1 {mu}m and diameter {approx}50 nm. Display Omitted Research Highlights: {yields} Microwave-assisted synthesis of undoped and Fe doped ZnO nanorods. {yields} Observation of room temperature ferromagnetism in undoped and Fe doped ZnO nanorods. {yields} Transition temperature (T{sub c}) obtained in undoped and doped samples is above 390 K. {yields} In undoped ZnO origin of ferromagnetism is explained in terms of defects/vacancies. {yields} Ferromagnetism in Fe doped ZnO is explained by F-center exchange mechanism.

  6. Oxygen vacancy induced by La and Fe into ZnO nanoparticles to modify ferromagnetic ordering

    NASA Astrophysics Data System (ADS)

    Verma, Kuldeep Chand; Kotnala, R. K.

    2016-05-01

    We reported long-range ferromagnetic interactions in La doped Zn0.95Fe0.05O nanoparticles that mediated through lattice defects or vacancies. Zn0.92Fe0.05La0.03O (ZFLaO53) nanoparticles were synthesized by a sol-gel process. X-ray fluorescence spectrum of ZFLaO53 detects the weight percentage of Zn, Fe, La and O. X-ray diffraction shows the hexagonal Wurtzite ZnO phase. The Rietveld refinement has been used to calculate the lattice parameters and the position of Zn, Fe, La and O atoms in the Wurtzite unit cell. The average size of ZFLaO53 nanoparticles is 99 nm. The agglomeration type product due to OH ions with La results into ZnO nanoparticles than nanorods that found in pure ZnO and Zn0.95Fe0.05O sample. The effect of doping concentration to induce Wurtzite ZnO structure and lattice defects has been analyzed by Raman active vibrational modes. Photoluminescence spectra show an abnormal emission in both UV and visible region, and a blue shift at near band edge is formed with doping. The room temperature magnetic measurement result into weak ferromagnetism but pure ZnO is diamagnetic. However, the temperature dependent magnetic measurement using zero-field and field cooling at dc magnetizing field 500 Oe induces long-range ferromagnetic ordering. It results into antiferromagnetic Neel temperature of ZFLaO53 at around 42 K. The magnetic hysteresis is also measured at 200, 100, 50 and 10 K measurement that indicate enhancement in ferromagnetism at low temperature. Overall, the La doping into Zn0.95Fe0.05O results into enhanced antiferromagnetic interaction as well as lattice defects/vacancies. The role of the oxygen vacancy as the dominant defects in doped ZnO must form Bound magnetic polarons has been described.

  7. An Assessment of the Al- Fe- N System

    NASA Astrophysics Data System (ADS)

    Hillert, Mats; Jonsson, Stefan

    1992-11-01

    The thermodynamic properties of the Al-Fe-N system are assessed, taking various types of information into account. For solid AIN, a description very similar to that given by JANAF is found to yield reasonable predictions for the solubility of A1N in face-centered cubic (fcc) Fe and in liquid Fe. An ionic two-sublattice model is applied to the liquid phase, containing two N species, N-3 and N0 The melting point of A1N is taken as 3068 K, and a required gas pressure of 9.75 bar is predicted. A sublimation point of 2690 K at 1 bar is also predicted. A plot of the liquidus surfaces in the Fe-rich end of the Al-Fe-N system is presented.

  8. Incorporation of Ba in Al and Fe pollucite

    NASA Astrophysics Data System (ADS)

    Vance, Eric R.; Gregg, Daniel J.; Griffiths, Grant J.; Gaugliardo, Paul R.; Grant, Charmaine

    2016-09-01

    Ba, the transmutation product of radioactive Cs, can be incorporated at levels of up to ∼0.07 formula units in Cs(1-2x)BaxAlSi2O6 aluminium pollucite formed by sol-gel methods and sintering at 1400 °C, with more Ba forming BaAl2Si2O8 phases. The effect of Ba substitution in pollucite-structured CsFeSi2O6 was also studied and no evidence of Ba substitution in the pollucite structure via cation vacancies or Fe2+ formation was obtained. The Ba entered a Fe-silicate glass structure. Charge compensation was also attempted with a Cs+ + Fe3+ ↔ Ba2+ + Ni2+ scheme but again the Ba formed a glass and NiO was evident. PCT leaching data showed CsFeSi2O6 to be very leach resistant.

  9. Mössbauer and SEM study of Fe Al film

    NASA Astrophysics Data System (ADS)

    Sebastian, Varkey; Sharma, Ram Kripal; Lakshmi, N.; Venugopalan, K.

    2006-04-01

    Fe Al alloy with Fe/Al ratio of 3:1 was first prepared by argon arc melting. It was subsequently coated on glass slide and cellophane tape using an electron beam gun system to have a thickness of 2,000 Å. X-ray diffraction spectrum of the coated sample indicates a definite texture for the film with a preferential growth along the Fe(110) plane. SEM micrographs of the film showed the presence of nano islands of nearly 3 × 1012/m2 surface density. Composition of different parts of the film was determined using EDAX. Room temperature Fe-57 Mössbauer spectrum of coated sample showed the presence a quadrupole doublet with a splitting of 0.46 mm/s, which is typical of Al-rich iron compounds. MOKE study shows an in-plane magnetic moment.

  10. Structural and Magnetic Properties of Transition-Metal-Doped Zn 1- x Fe x O

    NASA Astrophysics Data System (ADS)

    Abdel-Baset, T. A.; Fang, Yue-Wen; Anis, B.; Duan, Chun-Gang; Abdel-Hafiez, Mahmoud

    2016-02-01

    The ability to produce high-quality single-phase diluted magnetic semiconductors (DMS) is the driving factor to study DMS for spintronics applications. Fe-doped ZnO was synthesized by using a low-temperature co-precipitation technique producing Zn 1- x Fe x O nanoparticles ( x= 0, 0.02, 0.04, 0.06, 0.08, and 0.1). Structural, Raman, density functional calculations, and magnetic studies have been carried out in studying the electronic structure and magnetic properties of Fe-doped ZnO. The results show that Fe atoms are substituted by Zn ions successfully. Due to the small ionic radius of Fe ions compared to that of a Zn ions, the crystal size decreases with an increasing dopant concentration. First-principle calculations indicate that the charge state of iron is Fe 2+ and Fe 3+ with a zinc vacancy or an interstitial oxygen anion, respectively. The calculations predict that the exchange interaction between transition metal ions can switch from the antiferromagnetic coupling into its quasi-degenerate ferromagnetic coupling by external perturbations. This is further supported and explains the observed ferromagnetic bahaviour at magnetic measurements. Magnetic measurements reveal that decreasing particle size increases the ferromagnetism volume fraction. Furthermore, introducing Fe into ZnO induces a strong magnetic moment without any distortion in the geometrical symmetry; it also reveals the ferromagnetic coupling.

  11. Structural and Magnetic Properties of Transition-Metal-Doped Zn 1-x Fe x O.

    PubMed

    Abdel-Baset, T A; Fang, Yue-Wen; Anis, B; Duan, Chun-Gang; Abdel-Hafiez, Mahmoud

    2016-12-01

    The ability to produce high-quality single-phase diluted magnetic semiconductors (DMS) is the driving factor to study DMS for spintronics applications. Fe-doped ZnO was synthesized by using a low-temperature co-precipitation technique producing Zn 1-x Fe x O nanoparticles (x= 0, 0.02, 0.04, 0.06, 0.08, and 0.1). Structural, Raman, density functional calculations, and magnetic studies have been carried out in studying the electronic structure and magnetic properties of Fe-doped ZnO. The results show that Fe atoms are substituted by Zn ions successfully. Due to the small ionic radius of Fe ions compared to that of a Zn ions, the crystal size decreases with an increasing dopant concentration. First-principle calculations indicate that the charge state of iron is Fe (2+) and Fe (3+) with a zinc vacancy or an interstitial oxygen anion, respectively. The calculations predict that the exchange interaction between transition metal ions can switch from the antiferromagnetic coupling into its quasi-degenerate ferromagnetic coupling by external perturbations. This is further supported and explains the observed ferromagnetic bahaviour at magnetic measurements. Magnetic measurements reveal that decreasing particle size increases the ferromagnetism volume fraction. Furthermore, introducing Fe into ZnO induces a strong magnetic moment without any distortion in the geometrical symmetry; it also reveals the ferromagnetic coupling. PMID:26925863

  12. Interfacial Phenomena in Al/Al, Al/Cu, and Cu/Cu Joints Soldered Using an Al-Zn Alloy with Ag or Cu Additions

    NASA Astrophysics Data System (ADS)

    Pstruś, Janusz; Gancarz, Tomasz

    2014-05-01

    The studies of soldered joints were carried out in systems: Al/solder/Al, Al/solder/Cu, Cu/solder/Cu, where the solder was (Al-Zn)EUT, (Al-Zn)EUT with 0.5, 1.0, and 1.5 at.% of Ag and (Al-Zn)EUT with 0.5, 1.0, and 1.5 at.% of Cu addition. Brazing was performed at 500 °C for 3 min. The EDS analysis indicated that the composition of the layers starting from the Cu pad was CuZn, Cu5Zn8, and CuZn4, respectively. Wetting tests were performed at 500 °C for 3, 8, 15, and 30 min, respectively. Thickness of the layers and their kinetics of growth were measured based on the SEM micrographs. The formation of interlayers was not observed from the side of Al pads. On the contrary, dissolution of the Al substrate and migration of Al-rich particles into the bulk of the solder were observed.

  13. Magnetic properties and loss separation in FeSi/MnZnFe2O4 soft magnetic composites

    NASA Astrophysics Data System (ADS)

    Lauda, M.; Füzer, J.; Kollár, P.; Strečková, M.; Bureš, R.; Kováč, J.; Baťková, M.; Baťko, I.

    2016-08-01

    We investigated composites that have been prepared from FeSi powders covered with MnZnFe2O4 (MnZn ferrite), which was prepared by sol-gel synthesis accompanied with the auto-combustion process. The aim of this paper is to analyze the complex permeability and core losses of prepared samples with different amount of MnZn ferrite. The microstructure and the powder morphology were examined by scanning electron microscopy. Magnetic measurements on bulk samples were carried out using a vibrating sample magnetometer, an impedance analyzer and hysteresisgraphs. The results indicate that the composites with 2.6 wt% MnZn ferrite show better soft magnetic properties than the composites with about 6 wt% MnZn ferrite.

  14. Magnetic properties of spin frustrated spinel ZnFe{sub 2}O{sub 4}/ZnCr{sub 2}O{sub 4} superlattices

    SciTech Connect

    Murata, T.; Kozuka, Y. Uchida, M.; Kawasaki, M.

    2015-11-21

    Superlattice films composed of frustrated spin systems, [ZnFe{sub 2}O{sub 4}]{sub m}/[ZnCr{sub 2}O{sub 4}]{sub m}, are grown on MgAl{sub 2}O{sub 4} (111) substrates by pulsed laser deposition, and their frustrated magnetism is studied. The superlattice films show spin-glass behavior and the spin-glass transition temperature (T{sub g}) varies nonmonotonically as a function of the layer thickness m. T{sub g} increases with decreasing m due to an increase in the inhomogeneous exchange interaction between Cr{sup 3+} and Fe{sup 3+} at the interface. However, below m = 4, a decrease in T{sub g} is observed. Compared with the solid solution Zn(CrFe)O{sub 4} film and the other superlattices, the decrease in T{sub g} is considered to be a unique property of the periodically modulated short period superlattices.

  15. TEM study of Franklinite-hetaerolite (ZnFe{sub 2}O{sub 4}-ZnMn{sub 2}O{sub 4}) exsolution intergrowths

    SciTech Connect

    Gong, W.L.; Wang, L.M.; Ewing, R.C.

    1996-12-31

    The spinel structure-type is derived from ccp oxygen packing by cation occupation of one quarter of the tetrahedral and one half of the octahedral interstices with a general stoichiometry of AB{sub 2}O{sub 4}. Franklinite, ideally ZnFe{sub 2}O{sub 4}, was the dominant ore mineral of zinc at the great Franklin and Sterling Hill zinc deposits, New Jersey. Although the chemistry of franklinite conformed to the spinel formula, the composition showed a wide range in the porportions of iron, zinc, and manganese. The microscopic examination of polished sections of the Franklin spinel revealed oriented exsolution intergrowths of franklinite, magnetite (Fe{sup 2+}Fe{sup 3+}{sub 2}O{sub 4}), and gahnite (ideally ZnAl{sub 2}O{sub 4}). In this contribution, the exsolution intergrowths of franklinite and hetaerolite (ideally ZnMn{sub 2}O{sub 4}) are well characterized using JEM 2000FX and JEM 2010 electron microscopes operated at 200 keV.

  16. Behavior of Ni, Zn and Cr during low temperature aqueous Fe oxidation processes on Mars

    NASA Astrophysics Data System (ADS)

    Zhao, Yu-Yan S.; McLennan, Scott M.

    2013-05-01

    The behavior of Ni(II), Zn(II) and Cr(III) during the melanterite (FeSO4·7H2O) to hematite (α-Fe2O3) oxidative transformations involving evolution pathways via jarosite ((H3O,K)Fe3(OH)6(SO4)2), schwertmannite (Fe8O8(OH)6(SO4)) and goethite (α-FeOOH) were investigated in an acidic saturated MgSO4 matrix. Results provide important clues about how elevated levels of trace elements are incorporated into the secondary Fe mineralogy assemblages found on Mars and the mechanism for formation of hematitic concretions at Meridiani Planum on Mars. Our results demonstrate that starting at the same concentrations in the initial solution, final amounts of Ni, Zn and Cr in hematite via different pathways are very different. In Path 1 (melanterite → jarosite → hematite), partitioning of Ni, Zn and Cr into jarosite and hematite (formed through dissolution of jarosite) is most likely in the order: Cr > Zn > Ni. In Path 2 (melanterite → schwertmannite → goethite → hematite), schwertmannite and goethite exhibited strong affinities for divalent Ni and Zn. During such a pathway, Ni should accumulate more than Zn by at least a factor of two, and partitioning of Ni, Zn and Cr to the hematite is most likely in the order: Cr > Ni > Zn. Therefore, our results suggest that the high Ni and moderate Zn distribution pattern observed in Meridiani hematitic spherule-bearing samples can be explained best by the schwertmannite-goethite to hematite pathway (Path 2), without need for an additional high Ni source in this region. Although the lack of goethite at Meridiani renders it uncertain if goethite ever served as a precursor to facilitate hematite formation, dehydration of nano-crystalline goethite is thermodynamically favored and cannot be ruled out. On the other hand, if hematitic concretions were formed by dissolution of jarosite (Path 1), then much higher initial Ni/Zn ratios than 1 in initial diagenetic fluids may be necessary to explain the elevated levels of Ni in the spherules

  17. Charge Compensated (Al, N) Co-Doped Zinc Oxide (ZnO) Films for Photlelectrochemical Application

    SciTech Connect

    Shet, S.

    2012-01-01

    ZnO thin films with significantly reduced bandgaps were synthesized by doping N and co-doping Al and N at 100oC. All the films were synthesized by radio-frequency magnetron sputtering on F-doped tin-oxide-coated glass. We found that co-doped ZnO:(Al,N) thin films exhibited significantly enhanced crystallinity as compared to ZnO doped solely with N, ZnO:N, at the same growth conditions. Furthermore, annealed ZnO:(Al,N) thin films exhibited enhanced N incorporation over ZnO:N films. As a result, ZnO:(Al,N) films exhibited improved photocurrents than ZnO:N films grown with pure N doping, suggesting that charge-compensated donor-acceptor co-doping could be a potential method for bandgap reduction of wide-bandgap oxide materials to improve their photoelectrochemical performance.

  18. ZnO/Al:ZnO Transparent Resistive Switching Devices Grown by Atomic Layer Deposition for Memristor Applications.

    PubMed

    Mundle, Rajeh; Carvajal, Christian; Pradhan, Aswini K

    2016-05-17

    ZnO has intrinsic semiconductor conductivity because of an unintentional doping mechanism resulting from the growth process that is mainly attributable to oxygen vacancies (VO) positioned in the bandgap. ZnO has multiple electronic states that depend on the number of vacancies and the charge state of each vacancy. In addition to the individual electron states, the vacancies have different vibrational states. We developed a high-temperature precursor vapor mask technique using Al2O3 to pattern the atomic layer deposition of ZnO and Al:ZnO layers on ZnO-based substrates. This technique was used to create a memristor device based on Al:ZnO thin films having metallic and semiconducting and insulating transport properties ZnO. We demonstrated that adding combination of Al2O3 and TiO2 barrier layers improved the resistive switching behavior. The change in the resistance between the high- and low-resistivity states of the memristor with a combination of Al2O3 and TiO2 was approximately 157%. The devices were exposed to laser light from three different laser diodes. The 450 nm laser diode noticeably affected the combined Al2O3 and TiO2 barrier, creating a high-resistivity state with a 2.9% shift under illumination. The high-resistivity state shift under laser illumination indicates defect shifts and the thermodynamic transition of ZnO defects. PMID:27124366

  19. Lubrication performance and mechanisms of Mg/Al-, Zn/Al-, and Zn/Mg/Al-layered double hydroxide nanoparticles as lubricant additives

    NASA Astrophysics Data System (ADS)

    Li, Shuo; Bhushan, Bharat

    2016-08-01

    Solid lubricant particles are commonly used as oil additives for low friction and wear. Mg/Al-, Zn/Al-, and Zn/Mg/Al-layered double hydroxides (LDH) were synthesized by coprecipitation method. The benefits of LDH nanoparticles are that they can be synthesized using chemical methods where size and shape can be controlled, and can be modified organically to allow dispersal in fluids. The LDH nanoparticles were characterized by X-ray diffraction, scanning electron microscope, thermogravimetry, and differential scanning calorimetry. A pin-on-disk friction and wear tester was used for evaluating the friction and wear properties of LDH nanoparticles as lubricant additives. LDH nanoparticles have friction-reducing and anti-wear properties compared to oil without LDHs. Mg/Al-LDH has the best lubrication, possibly due to better thermal stability in severe conditions.

  20. Colorimetric detection of urine glucose based ZnFe2O4 magnetic nanoparticles.

    PubMed

    Su, Li; Feng, Jie; Zhou, Ximin; Ren, Cuiling; Li, Honghong; Chen, Xingguo

    2012-07-01

    In this paper, we discovered that ZnFe(2)O(4) magnetic nanoparticles (MNPs) possess intrinsic peroxidase-like activity. ZnFe(2)O(4) MNPs exhibit several advantages such as high catalytic efficiency, good stability, monodispersion, and rapid separation over other peroxidase nanomimetics and horseradish peroxidase (HRP). ZnFe(2)O(4) MNPs were used as a colorimetric biosensor for the detection of urine glucose. This method is simple, inexpensive, highly sensitive, and selective for glucose detection using glucose oxidase (GOx) and ZnFe(2)O(4) MNPs with a linear range from 1.25 × 10(-6) to 1.875 × 10(-5) mol L(-1) with a detection limit of 3.0 × 10(-7) mol L(-1). The color change observable by the naked eyes based on the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) is the principle for the sensing of urine glucose level. PMID:22702236

  1. Fe doped ZnO thin film for mediator-less biosensing application

    NASA Astrophysics Data System (ADS)

    Saha, Shibu; Tomar, Monika; Gupta, Vinay

    2012-05-01

    Fe doped ZnO (FZO) thin film is prepared by pulsed laser deposition for its application as mediator-less biosensing matrix. Fe doping introduces redox centre in ZnO along with shallow donor level and promotes the electron transfer capability due to substitution of Fe at Zn sites. Glucose oxidase (GOx), chosen as model enzyme, was immobilized on surface of the prepared matrix. Cyclic voltammetry and photometric assay show that the developed bio-electrode, GOx/FZO/indium tin oxide/Glass is sensitive to glucose concentration with enhanced response (0.2 µA mM-1 cm-2) and low Km (3.01 mM). The results show promising application of Fe doped ZnO thin film as an attractive matrix for mediator-less biosensing.

  2. Synthesis, characterization and conductivity studies of ZnFe{sub 2}O{sub 4} nanoparticles

    SciTech Connect

    Narsimulu, D.; Satyanarayana, N.; Venkateswarlu, M.

    2015-06-24

    Transition metal ferrites with general formula AB{sub 2}O{sub 4} (A=Co, Cu, Mn, Zn, B=Fe{sup +3}) could be used as an anode materials in lithium ion battery (LIB), because, lithium ion batteries fabricated using ferrite materials show the high capacity than commonly used graphite. The ZnFe{sub 2}O{sub 4} with cubic spinel structured material was prepared by acrylamide assisted citrate combustion process. Phase, structural coordination and thermal behavior of the prepared ZnFe{sub 2}O{sub 4} were confirmed by powder X-ray diffraction, FTIR spectra and TG/DTA thermogram respectively. Morphology and specific surface area of the ZnFe{sub 2}O{sub 4} were identified by SEM and BET surface analyzer respectively and its conductivity studies were made through impedance spectroscopy.

  3. Synthesis of Fe Doped ZnO Nanowire Arrays that Detect Formaldehyde Gas.

    PubMed

    Jeon, Yoo Sang; Seo, Hyo Won; Kim, Su Hyo; Kim, Young Keun

    2016-05-01

    Owing to their chemical and thermal stability and doping effects on providing electrons to the conduction band, doped ZnO nanowires have generated interest for use in electronic devices. Here we report hydrothermally grown Fe-doped ZnO nanowires and their gas-sensing properties. The synthesized nanowires have a high crystallinity and are 60 nm in diameter and 1.7 μm in length. Field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) are employed to understand the doping effects on the microstructures and gas sensing properties. When the Fe-doped ZnO nanowire arrays were evaluated for gas sensing, responses were recorded through changes in temperature and gas concentration. Gas sensors consisting of ZnO nanowires doped with 3-5 at.% Fe showed optimum formaldehyde (HCHO) sensing performance at each working temperature. PMID:27483827

  4. Synthesis, characterization and conductivity studies of ZnFe2O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Narsimulu, D.; Venkateswarlu, M.; Satyanarayana, N.

    2015-06-01

    Transition metal ferrites with general formula AB2O4 (A=Co, Cu, Mn, Zn, B=Fe+3) could be used as an anode materials in lithium ion battery (LIB), because, lithium ion batteries fabricated using ferrite materials show the high capacity than commonly used graphite. The ZnFe2O4 with cubic spinel structured material was prepared by acrylamide assisted citrate combustion process. Phase, structural coordination and thermal behavior of the prepared ZnFe2O4 were confirmed by powder X-ray diffraction, FTIR spectra and TG/DTA thermogram respectively. Morphology and specific surface area of the ZnFe2O4 were identified by SEM and BET surface analyzer respectively and its conductivity studies were made through impedance spectroscopy.

  5. Preparation of soft magnetic composites for Fe particles coated with (NiZn)Fe2O4 via microwave treatment

    NASA Astrophysics Data System (ADS)

    Peng, Yuandong; Nie, Junwu; Zhang, Wenjun; Bao, Chongxi; Ma, Jian; Cao, Yang

    2015-12-01

    Soft magnetic composites (SMCs) of Fe particles coated with fine particle Ni0.5Zn0.5Fe2O4 ferrite were prepared via microwave heat treatment, and the magnetic properties and microstructures of these composites were investigated. The results show that a well-distributed Ni0.5Zn0.5Fe2O4 coating layer was formed on the surface of the Fe particles upon microwave annealing. The SMCs sample treated by microwave heating at 800 °C for 30 min under N2 had a perfect insulation layer between the Fe particles and showed stable permeability and low core loss as well as good magnetic characteristics over a wide frequency range.

  6. Synthesis, structure and magnetic properties of L10 alloy (FePt)100- x Zn x nanoparticles

    NASA Astrophysics Data System (ADS)

    Zeynali, Hossein; Akbari, Hossein; Bakhshayeshi, Ali

    2016-04-01

    In the present work, alloy (FePt)100- x Zn x nanoparticles have been successfully synthesized by simple wet chemical method with the aid of Pt(acac)2, Fe(acac)3 and Zn(acac)2 as the starting reagents. Oleic acid and oleylamine was used as a surfactant agent. The addition of zinc promoted the face-centered cubic to tetragonal phase transition. Reduction in temperature required for this transition compared with FePt nanoparticles with no additives. This reduction in ordering temperature significantly reduces FePt particle coalescence and enhancing chemical ordering, so magnetic measurements show high coercivity up to 6 kOe of the (FePt)82Zn18 nanoparticles with average size <10 nm after annealing at 500 °C for 60 min. The coercivity increases with the content of zinc up to 18 %, and above this percent, the coercivity starts to decrease. In order to calculate magnetic properties for Zn in FePt: Zn structure, we used density functional theory and GGA approximation. The energy of FePt: Zn structure in which Zn atom replaces Fe ones is lower than other possible structures, so forming of this system is more probable. Calculations show than Zn atoms do not have a significant magnetic momentum when replacing Fe atoms. Curie temperature variation as a function of added Zn atoms is derived. Added Zn atoms replace Fe atoms and previous Fe site is occupied with Zn with approximately zero magnetic momentum. Since these sites are randomly occupied, we have random exchange interactions in the system which can be modeled like spin glass system. Zn atoms have a zero magnetic momentum when replacing Fe atoms, so total magnetic momentum and Curie temperature of FePt: Zn structure decrease with increasing Zn percentage.

  7. The evolution of authigenic Zn-Pb-Fe-bearing phases in the Grieves Siding peat, western Tasmania

    NASA Astrophysics Data System (ADS)

    Awid-Pascual, Richelle; Kamenetsky, Vadim S.; Goemann, Karsten; Allen, Neil; Noble, Taryn L.; Lottermoser, Bernd G.; Rodemann, Thomas

    2015-08-01

    A thick peat profile overlying mineralized metasediments possesses exceptionally high base metal contents (up to 28.6 wt% Zn and up to 3.8 wt% Pb) in the form of abundant detrital and authigenic minerals. This metal-rich peat was examined using X-ray diffraction, scanning electron microscopy and Raman spectroscopy to determine the characteristics, mineral associations, phase evolution and conditions of formation of Zn-Pb-Fe-bearing minerals within the peat. Mineral assemblages consisting of sulfides, silicates, sulfates, oxides, carbonates and phosphates could be classified as follows: (1) detrital minerals supplied by the surrounding rocks (i.e., Cambrian volcanics and sediments, Ordovician carbonates) and (2) authigenic phases that are precipitated in situ, including the predominant Zn-Pb-Fe-bearing phases. Detrital minerals are characterized by weathering-related morphologies (e.g., round, smooth surfaces and angular edges and dissolution pits), whereas authigenic phases are recognized by their delicate microparticle textures (e.g., bladed, framboidal and botryoidal textures). Zinc-bearing phases are represented by non-stoichiometric phases, also containing S, C, O and Al; sphalerite, baileychlore and Fe-Zn-Pb carbonate. Authigenic Pb- and Fe-bearing phases are also present in the peat such as galena, anglesite, plumbojarosite, magnetite and pyrite. A "line of descent" of authigenic sulfides has been established, suggesting that a non-stoichiometric, possibly amorphous Zn-rich phase is a precursor to the sphalerite. Stages of pyrite formation, where massive polycrystalline pyrite is produced via disseminated and framboidal pyrite, have also been hypothesized in this study. The assemblages of authigenic minerals in the peat reflect dynamic physical and chemical conditions, including biological processes, and are not necessarily in equilibrium with each other.

  8. Enhanced UV Photocatalytic Performance of Magnetic Fe3O4/CuO/ZnO/NGP Nanocomposites

    NASA Astrophysics Data System (ADS)

    Tju, Hendry; Taufik, Ardiansyah; Saleh, Rosari

    2016-04-01

    Fe3O4/CuO/ZnO/nanographene platelets (Fe3O4/CuO/ZnO/NGP) with varied ZnO loadings have been synthesized using a sol-gel method followed by hydrothermal method. X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) confirmed the formation of the Fe3O4/CuO/ZnO/NGP composites. All of the samples showed the presence of graphene nanoplatelets incorporating Fe3O4, CuO and ZnO structures and exhibited ferromagnetic behavior at room temperature. The composites showed photocatalytic activity under UV irradiation, which was used to affect the degradation of methylene blue. The Fe3O4/CuO/ZnO/NGP composites showed superior photocatalytic activity than the Fe3O4/CuO/ZnO materials.

  9. Structural And Magnetic Properties Of Mn And Zn Doped Fe3O4 Nanoparticles

    NASA Astrophysics Data System (ADS)

    Varshney, Dinesh; Verma, Kavita; Yogi, A.

    2011-07-01

    Mn and Zn doped Fe3O4 nanoparticles of size 7.36 and 12.52 nm were prepared by co precipitation method. X-ray diffraction (XRD) pattern infers that both the samples are in single phase with Fd3m space group, which was further confirmed by Rietveld refinement. Transmission Mössbauer spectra reveals ferrimagnetic nature for Mn doping concentration while into that for Zn doping concentration it shows diamagnetic behaviour. Zn doped nanoparticles shows the superparamagnetic property.

  10. Experimental study of thermal oxidation of nanoscale alloys of aluminium and zinc (nAlZn)

    NASA Astrophysics Data System (ADS)

    Noor, Fahad; Wen, Dongsheng

    2015-10-01

    Aluminium-based alloys have wide applications but little is known about the thermal-chemical kinetics of nanoalloys. This work investigated the thermal oxidation of Zn and Al nanoalloys (nAlZn) with a BET equivalent diameter of 141 nm through the simultaneous TGA/DSC method. The thermal analysis was combined with elemental, morphology and crystalline structure analysis to elucidate the reaction mechanisms. It was found that the complete oxidation of nAlZn in air can be characterised by a three-stage process, including two endothermic and three exothermic reactions. With the help of ex-situ XRD, different reaction pathways were proposed for different stages, forming the end products of ZnO and ZnAl2O4. The reactivity comparison between Al and nAlZn suggested that different criteria should be used for different applications.

  11. Host Atom Diffusion in Ternary Fe-Cr-Al Alloys

    NASA Astrophysics Data System (ADS)

    Rohrberg, Diana; Spitzer, Karl-Heinz; Dörrer, Lars; Kulińska, Anna J.; Borchardt, Günter; Fraczkiewicz, Anna; Markus, Torsten; Jacobs, Michael H. G.; Schmid-Fetzer, Rainer

    2014-01-01

    In the Fe-rich corner of the Fe-Cr-Al ternary phase diagram, both interdiffusion experiments [1048 K to 1573 K (775 °C to 1300 °C)] and 58Fe tracer diffusion experiments [873 K to 1123 K (600 °C to 850 °C)] were performed along the Fe50Cr50-Fe50Al50 section. For the evaluation of the interdiffusion data, a theoretical model was used which directly yields the individual self-diffusion coefficients of the three constituents and the shift of the original interface of the diffusion couple through inverse modeling. The driving chemical potential gradients were derived using a phenomenological Gibbs energy function which was based on thoroughly assessed thermodynamic data. From the comparison of the individual self-diffusivities of Fe as obtained from interdiffusion profiles and independent 58Fe tracer diffusivities, the influence of the B2-A2 order-disorder transition becomes obvious, resulting in a slightly higher activation enthalpy for the bcc-B2 phase and a significantly lower activation entropy for this phase.

  12. The corrosion behavior of Fe-Mn-Al weld metals

    NASA Astrophysics Data System (ADS)

    Aidun, Daryush K.

    2001-02-01

    The corrosion resistance of a newly developed iron-base, Fe-Mn-Al austenitic, and duplex weld metal has been examined in the NACE solution consisting of 5 wt.% NaCl, 0.5 wt.% acetic acid, and the balance distilled water. The electrochemical techniques such as potentiodynamic polarization, Tafel plots, linear polarization, cyclic polarization, and open-circuit potential versus time were employed. The Fe-Mn-Al weld metals did not passivate and exhibited high corrosion rates. Fe-Cr-Ni (310 and 316) weld and base metals were also examined in the NACE solution at room temperature. The 310 and 316 base metals were more resistant to corrosion than the as-welded 310 and 316 weld metals. Postweld heat treatment (PWHT) improved the corrosion performance of the Fe-Mn-Al weld metals. The corrosion resistance of Fe-Mn-Al weld metals after PWHT was still inferior to that of the 310 and 316 weld and base metals.

  13. ZnFe2O4 nanoparticles for potential application in radiosensitization

    NASA Astrophysics Data System (ADS)

    Hidayatullah, M.; Nurhasanah, I.; Budi, W. S.

    2016-03-01

    Radiosensitizer is a material that can increase the effects of radiation in radiotherapy application. Various materials with high effective atomic number have been developed as a radiosensitizer, such as metal, iron oxide and quantum dot. In this study, ZnFe2O4 nanoparticles are included in iron oxide class were synthesized by precipitation method from the solution of zinc nitrate and ferrite nitrate and followed by calcination at 700° C for 3 hours. The XRD pattern shows that most of the observed peaks can be indexed to the cubic phase of ZnFe2O4 with a lattice parameter of 8.424 Å. SEM image reveals that nanoparticles are the sphere-like shape with size in the range 84-107 nm. The ability of ZnFe2O4 nanoparticles as radiosensitizer was examined by loading those nanoparticles into Escherichia coli cell culture which irradiated with photon energy of 6 MV at a dose of 2 Gy. ZnFe2O4 nanoparticles showed ability to increase the absorbed dose by 0.5 to 1.0 cGy/g. In addition, the presence of 1 g/L ZnFe2O4 nanoparticles resulted in an increase radiation effect by 6.3% higher than if exposed to radiation only. These results indicated that ZnFe2O4 nanoparticles can be used as the radiosensitizer for increasing radiation effect in radiotherapy.

  14. Effect of Fe doping concentration on photocatalytic activity of ZnO nanosheets under natural sunlight

    SciTech Connect

    Khokhra, Richa; Kumar, Rajesh

    2015-05-15

    A facile room temperature, aqueous solution-based chemical method has been adopted for large-scale synthesis of Fe doped ZnO nanosheets. The XRD and SEM results reveal the as-synthesized products well crystalline and accumulated by large amount of interweave nanosheets, respectively. Energy dispersive spectroscopy data confirmed Fe doping of the ZnO nanosheets with a varying Fe concentration. The photoluminescence spectrum reveals a continuous suppression of defect related emissions intensity by increasing the concentration of the Fe ion. A photocatalytic activity using these samples under sunlight irradiation in the mineralization of methylene blue dye was investigated. The photocatalytic activity of Fe doped ZnO nanosheets depends upon the presence of surface oxygen vacancies.

  15. Growth and photorefractive properties of Zn, Fe double-doped LiTaO 3 crystal

    NASA Astrophysics Data System (ADS)

    Fang, Shuangquan; Wang, Biao; Zhang, Tao; Ling, Furi; Wang, Rui

    2006-02-01

    Zn, Fe double-doped LiTaO3 crystals have been grown by the Czochralski method. The photorefractive properties and optical damage resistance were measured by the two-beam coupling experiments and transmitted facula distortion method, respectively. The results showed that the photorefractive response speed of Zn:Fe:LiTaO3 was about four times faster than that of Fe:LiTaO3, whereas the optical damage resistance was two orders of magnitude higher than that of Fe:LiTaO3. In this paper, site occupation mechanism of impurities was also discussed to explain the high optical damage resistance and fast response speed of Zn:Fe:LiTaO3 crystal.

  16. Highly efficient and selective adsorption of In3+ on pristine Zn/Al layered double hydroxide (Zn/Al-LDH) from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Barnabas, Mary Jenisha; Parambadath, Surendran; Mathew, Aneesh; Park, Sung Soo; Vinu, Ajayan; Ha, Chang-Sik

    2016-01-01

    A pristine Zn/Al-layered double hydroxide (Zn/Al-LDH) showed excellent adsorption ability and selectivity towards In3+ ions from aqueous solutions. The adsorption behaviour as a function of the contact time, solution pH, ionic strength, and amount of adsorbent under ambient conditions revealed a strong dependency on the pH and ionic strength over In3+ intake. The structure and properties of Zn/Al-LDH and In3+ adsorbed Zn/Al-LDH (In-Zn/Al-LDH) were examined carefully by X-ray diffraction, Fourier transform infrared spectroscopy, N2-sorption/desorption, UV-vis spectroscopy, and X-ray photoelectron spectroscopy. The adsorbent had a sufficient number of active sites that were responsible for the In3+ adsorption and quite stable even after the adsorption process. The selective adsorption of In3+ on Zn/Al-LDH was also observed even from a mixture containing competing ions, such as Mn2+, Co2+, Ni2+, Cd2+, Pb2+, and Cu2+. The adsorption experiments showed that Zn/Al-LDH is a promising material for the pre-concentration and selective removal of In3+ from large volumes of aqueous solutions.

  17. Effect of cation substitution at the B site on the oxygen semi-permeation flux in La0.5Ba0.5Fe0.7B0.3O3-δ dense perovskite membranes with B = Al, Co, Cu, Mg, Mn, Ni, Sn, Ti and Zn (part II)

    NASA Astrophysics Data System (ADS)

    Reichmann, M.; Geffroy, P.-M.; Fouletier, J.; Richet, N.; Del Gallo, P.; Chartier, T.

    2015-03-01

    The aim of this paper is to provide insight into the effect of cation substitution at the B site on the oxygen semi-permeation performances. Particular attention is given here to identify the impact of cation substitution at the B site on oxygen diffusion and oxygen surface-exchange kinetics in the La0.5Ba0.5Fe0.7B0.3O3-δ perovskite membrane series with B = Al, Co, Cu, Mg, Mn, Ni, Sn, Ti and Zn. This study clearly shows that the prediction of the oxygen semi-permeation performances of membrane materials from the nature of cation at the A or B sites in perovskite structure is quite complex. The cation substitution at the B-site has a low impact on the nature of rate-determining step and a significant impact on oxygen semi-permeation performances, contrary to the cation substitution at A-site. Unfortunately, it is not possible to establish a relevant trend about the effect of the nature of cation in the A or B sites in perovskite structure on oxygen diffusion and the oxygen surface-exchange kinetics.

  18. Doping concentration driven morphological evolution of Fe doped ZnO nanostructures

    SciTech Connect

    Sahai, A.; Goswami, N.; Kumar, Y.; Agarwal, V.; Olive-Méndez, S. F.

    2014-10-28

    In this paper, systematic study of structural, vibrational, and optical properties of undoped and 1-10 at.% Fe doped ZnO nanostructures, synthesized adopting chemical precipitation route, has been reported. Prepared nanostructures were characterized employing an assortment of microscopic and spectroscopic techniques, namely Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray (EDX) Spectroscopy, X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), Micro-Raman Spectroscopy (μRS), and UV-visible and Photoluminescence (PL) spectroscopy. With Fe incorporation, a gradual morphological transformation of nanostructures is demonstrated vividly through SEM/TEM characterizations. Interestingly, the morphology of nanostructures evolves with 1–10 at. % Fe doping concentration in ZnO. Nanoparticles obtained with 1 at. % Fe evolve to nanorods for 3 at. % Fe; nanorods transform to nanocones (for 5 at. % and 7 at. % Fe) and finally nanocones transform to nanoflakes at 10 at. % Fe. However, at all these stages, concurrence of primary hexagonal phase of Zn{sub 1-x}Fe{sub x}O along with the secondary phases of cubic ZnFe{sub 2}O{sub 4} and rhombohedric Fe{sub 2}O{sub 3}, is revealed through XRD analysis. Based on collective XRD, SEM, TEM, and EDX interpretations, a model for morphological evolution of nanostructures was proposed and the pivotal role of Fe dopant was deciphered. Furthermore, vibrational properties analyzed through Raman and FTIR spectroscopies unravel the intricacies of formation and gradual enhancement of secondary phases with increased Fe concentration. UV-visible and PL spectroscopic analyses provided further insight of optical processes altering with Fe incorporation. The blue shift and gradual quenching of visible photoluminescence with Fe doping was found in accordance with structural and vibrational analyses and explicated accordingly.

  19. Understanding the role of iron in the magnetism of Fe doped ZnO nanoparticles.

    PubMed

    Beltrán, J J; Barrero, C A; Punnoose, A

    2015-06-21

    The actual role of transition metals like iron in the room temperature ferromagnetism (RTFM) of Fe doped ZnO nanoparticles is still an unsolved problem. While some studies concluded that the Fe ions participate in the magnetic interaction, others in contrast do not believe Fe to play a direct role in the magnetic exchange interaction. To contribute to the understanding of this issue, we have carefully investigated the structural, optical, vibrational and magnetic properties of sol-gel synthesized Zn1-xFexO (0 < x < 0.10) nanoparticles. No Fe(2+) was detected in any sample. We found that high spin Fe(3+) ions are substitutionally incorporated at the Zn(2+) in the tetrahedral-core sites and in pseudo-octahedral surface sites in ZnO. Superficial OH(-) was observed in all samples. For x ≤ 0.03, an increment in Fe doping concentration decreased a and c lattice parameters, average Zn-O bond length, average crystallite size and band gap; while it increased the degree of distortion and quadrupole splitting. Undoped ZnO nanoparticles exhibited very weak RTFM with a saturation magnetization (Ms) of ∼0.47 memu g(-1) and this value increased to ∼2.1 memu g(-1) for Zn0.99Fe0.01O. Very interestingly, the Ms for Zn0.99Fe0.01O and Zn0.97Fe0.03O increased by a factor of about ∼2.3 by increasing annealing for 1 h to 3 h. For x ≥ 0.05, ferrimagnetic disordered spinel ZnFe2O4 was formed and this phase was found to become more ordered with increasing annealing time. Fe does not contribute directly to the RTFM, but its presence promoted the formation of additional single charged oxygen vacancies, zinc vacancies, and more oxygen-ended polar terminations at the nanoparticle surface. These defects, which are mainly superficial, altered the electronic structure and are considered as the main sources of the observed ferromagnetism. PMID:25994044

  20. Comparison of Fe-AlPILC and Fe-ZSM-5 catalysts used for degradation of methomyl

    NASA Astrophysics Data System (ADS)

    Lázár, Károly; Tomašević, Andjelka; Bošković, Goran; Kiss, Ernő

    2009-07-01

    Catalytic performances of Fe-AlPILC (14 wt.% Fe) and Fe-ZSM-5 (5 wt.% Fe) catalysts are compared in the wet oxidative degradation of methomyl. Fe-ZSM-5 exhibits outstanding whereas Fe-AlPILC shows only mediocre activity. Positions of iron are analysed in the two catalysts by Mössbauer spectroscopy. Iron is in highly dispersed state in Fe-AlPILC whereas in the other case a hematite/ZSM-5 composite is formed. The catalytic activity is attributed to iron located and stabilized in ionic dispersion.

  1. Influence of sediment components on the immobilization of Zn during microbial Fe-(hydr)oxide reduction.

    PubMed

    Coby, Aaron J; Picardal, Flynn W

    2006-06-15

    The fate of Zn and other sorbed heavy metals during microbial reduction of iron oxides is different when comparing synthetic Fe-(hydr)oxides and natural sediments undergoing a similar degree of iron reduction. Batch experiments with the iron-reducing organism Shewanella putrefaciens were conducted to examine the effects of an aqueous complexant (nitrilotriacetic acid or NTA), two solid-phase complexants (kaolinite and montmorillonite), an electron carrier (anthraquinone disulfonic acid or AQDS), and a humic acid on the speciation of Zn during microbial reduction of synthetic goethite. Compared to systems containing only goethite and Zn, microbial Fe(III) reduction in the presence of clay resulted in up to a 50% reduction in Zn immobilization (insoluble in a 2 h 0.5 M HCl extraction) without affecting Fe(II) production. NTA (3 mM) increased Fe(II) production 2-fold and resulted in recovery of nearly 75% of Zn in the aqueous fraction. AQDS (50 microM) resulted in a 12.5% decrease in Fe(II) production and a 44% reduction in Zn immobilization. Humic acid additions resulted in up to a 25% decrease in Fe(II) production and 51% decrease in Zn immobilization. The results suggest that all the components examined here as either complexing agents or electron shuttles reduce the degree of Zn immobilization by limiting the availability of Zn for incorporation into newly formed biogenic minerals. These results have implications for the remediation of heavy metals in a variety of natural sediments. PMID:16830547

  2. Seasonal variations in the translocation of micronutrients (Fe, Zn and Cu) from soil to shoots using isotopic compositions

    NASA Astrophysics Data System (ADS)

    Pichat, S.; Fekiacova, Z.; Cadiou, J.

    2011-12-01

    We have investigated the uptake and translocation of three essential micronutrients (Fe, Zn and Cu) in four plant species using both concentrations and isotopic compositions. The goals were (1) to document the evolution of isotopic compositions in the soil and the shoots over a year, (2) to test the effect of senescence on the translocation of the micronutrients and (3) to test the effect of types of plant cover on the isotopic composition of both plants and soils. The plants were chosen to maximize the physiological (annual vs. perennial, woody vs. herbaceous) and taxonomical differences (monocotyledon vs. dicotyledon). The experiment was conducted in the field at the Oak Observatory at the Haute-Provence Observatory (O3HP), France. The area has been a fallow land for 70 years and is located far away from any anthropic pollution source. The area has been subdivided in four zones as a function of plant cover. On average, shoots are enriched in heavy Zn and Cu isotopes at fall compared to spring. The senescent leaves of oak (Quercus pubescens) and smoke bush (Cotinus coggygria) are enriched in heavy Zn isotopes and have lower Zn concentrations than the green ones. This behavior is in agreement with kinetic fractionation of Zn isotopes associated to the redistribution of Zn from senescent to green leaves by the phloem. Cu concentrations are similar in green and senescent leaves of the same species and there is no systematic behavior in terms of Cu isotopic composition. Hence, Cu does not appear to be redistributed at senescence. Previous studies have shown that strategy I plants shoots were enriched in light Fe isotopes1,2,3 compared to the soil, while there was a small enrichment in heavy isotopes (Δ56Feshoot-soil < 0.2%) for strategy II plants1 (Δ56Feshoot-soil = δ56Feshoot - δ56Fesoil; δ56Fe = [(56Fe/54Fe)sample/(56Fe/54Fe)std -1] × 103). To interpret these fractionations reduction of Fe(III) to Fe(II) before uptake was suggested to occur for strategy I

  3. Synthesis of Zn-Fe layered double hydroxides via an oxidation process and structural analysis of products

    NASA Astrophysics Data System (ADS)

    Morimoto, Kazuya; Tamura, Kenji; Anraku, Sohtaro; Sato, Tsutomu; Suzuki, Masaya; Yamada, Hirohisa

    2015-08-01

    The synthesis of Zn-Fe(III) layered double hydroxides was attempted, employing different pathways using either Fe(II) or Fe(III) species together with Zn as the initial reagents. The product derived from the synthesis employing Fe(II) was found to transition to a Zn-Fe(III) layered double hydroxides phase following oxidation process. In contrast, the product obtained with Fe(III) did not contain a layered double hydroxides phase, but rather consisted of simonkolleite and hydrous ferric oxide. It was determined that the valency of the Fe reagent used in the initial synthesis affected the generation of the layered double hydroxides phase. Fe(II) species have ionic radii and electronegativities similar to those of Zn, and therefore are more likely to form trioctahedral hydroxide layers with Zn species.

  4. Highly selective fluorescent chemosensor for detection of Fe3+ based on Fe3O4@ZnO

    PubMed Central

    Li, Jingshuai; Wang, Qi; Guo, Zhankui; Ma, Hongmin; Zhang, Yong; Wang, Bing; Bin, Du; Wei, Qin

    2016-01-01

    The combination of fluorescent nanoparticles and specific molecular probes appears to be a promising strategy for developing fluorescent nanoprobes. In this work, L-cysteine (L-Cys) capped Fe3O4@ZnO core-shell nanoparticles were synthesized for the highly selective detection of Fe3+. The proposed nanoprobe shows excellent fluorescent property and high selectivity for Fe3+ due to the binding affinity of L-Cys with Fe3+. The binding of Fe3+ to the nanoprobe induces an apparent decrease of the fluorescence. Thus a highly selective fluorescent chemosensor for Fe3+ was proposed based on Fe3O4@ZnO nanoprobe. The magnetism of the nanoprobe enables the facile separation of bound Fe3+ from the sample solution with an external magnetic field, which effectively reduces the interference of matrix. The detection limit was 3 nmol L−1 with a rapid response time of less than 1 min. The proposed method was applied to detect Fe3+ in both serum and wastewater samples with acceptable performance. All above features indicated that the proposed fluorescent probe as sensing platform held great potential in applications of biological and analytical field. PMID:27000972

  5. FeAl-TiC and FeAl-WC composites - melt infiltration processing, microstructure and mechanical properties

    SciTech Connect

    Subramanian, R.; Schneibel, J.H.

    1997-04-01

    TiC-based and WC-based cermets were processed with iron aluminide, an intermetallic, as a binder by pressureless melt infiltration to near full density (> 97 % theoretical density). Phase equilibria calculations in the quaternary Fe-Al-Ti-C and Fe-Al-W-C systems at 145{degrees}C were performed to determine the solubility of the carbide phases in liquid iron aluminide. This was done by using Thermocalc{trademark} and the results show that molten Fe-40 at.% Al in equilibrium with Ti{sub 0.512}C{sub 0.488} and graphite, dissolves 4.9 at% carbon and 64 atomic ppm titanium. In the Fe-Al-W-C system, liquid Fe-40 at.% Al in equilibrium with graphite dissolves about 5 at.% carbon and 1 at.% tungsten. Due to the low values for the solubility of the carbide phases in liquid iron aluminide, liquid phase sintering of mixed powders does not yield a dense, homogeneous microstructure for carbide volume fractions greater than 0.70. Melt infiltration of molten FeAl into TiC and WC preforms serves as a successful approach to process cermets with carbide contents ranging from 70 to 90 vol. %, to greater than 97% of theoretical density. Also, the microstructures of cermets prepared by melt infiltration were very homogeneous. Typical properties such as hardness, bend strength and fracture toughness are reported. SEM observations of fracture surfaces suggest the improved fracture toughness to result from the ductility of the intermetallic phase. Preliminary experiments for the evaluation of the oxidation resistance of iron aluminide bonded cermets indicate that they are more resistant than WC-Co cermets.

  6. Crystal Structure and Magnetic Properties of New Cubic Quaternary Compounds RT2Sn2Zn18 (R = La, Ce, Pr, and Nd, and T = Co and Fe)

    NASA Astrophysics Data System (ADS)

    Isikawa, Yosikazu; Mizushima, Toshio; Ejiri, Jun-ichi; Kitayama, Shiori; Kumagai, Keigou; Kuwai, Tomohiko; Bordet, Pierre; Lejay, Pascal

    2015-07-01

    The new cubic quaternary intermetallic compounds RT2Sn2Zn18 (R = La, Ce, Pr, and Nd, and T = Co and Fe) were synthesized by the mixture-metal flux method using Zn and Sn. The crystal structure was investigated by powder X-ray diffraction and with a four-circle X-ray diffractometer using single crystals. The space group of the compounds is Fdbar{3}m (No. 227). The rare-earth atom is at the cubic site which is the center of a cage composed of Zn and Sn atoms. The crystal structure is the same as the CeCr2Al20-type crystal structure except the atoms at the 16c site, i.e., the Zn atoms at the 16c site are completely replaced by Sn atoms, indicating that the compounds are crystallographically new ordered quaternary compounds. The lattice parameter a and the physical properties of the magnetic susceptibility χ, the magnetization M, and the specific heat C of these cubic caged compounds were investigated. LaCo2Sn2Zn18 and LaFe2Sn2Zn18 are enhanced Pauli paramagnets that originate from the Co and Fe itinerant 3d electrons. CeCo2Sn2Zn18 and CeFe2Sn2Zn18 are also enhanced Pauli paramagnets that originate from both the 3d electrons and Ce 4f electrons. PrCo2Sn2Zn18 and PrFe2Sn2Zn18 are nonmagnetic materials with huge values of C divided by temperature, which indicates that the ground state of Pr ions is a non-Kramers' doublet. NdCo2Sn2Zn18 and NdFe2Sn2Zn18 are magnetic materials with the Néel temperatures of 1.0 and 3.8 K, respectively. All eight compounds have large magnetic moments of Co/Fe in the paramagnetic temperature region, and thus their magnetic moments are inferred to be magnetically frustrating owing to the pyrochlore lattice in the low-temperature region.

  7. Formation of interfacial compounds and the effects on stripping behaviors of a cold-sprayed Zn-Al coating on interstitial-free steel

    NASA Astrophysics Data System (ADS)

    Liang, Y. L.; Wang, Z. B.; Zhang, J. B.; Lu, K.

    2015-06-01

    By means of cold spray, a Zn-Al coating was successfully deposited on an interstitial-free (IF) steel sheet. The formation of interfacial compounds between the coating and the IF steel was studied during diffusion annealing at 400 °C. And its correlations with the stripping behaviors of the coating were investigated by using a three-point bending method. The results showed that Fe-Zn and Fe-Al-Zn compounds begin to form at the coating/substrate interface after an annealing duration of 60 min, and the stripping resistance increases slightly before that duration and then decreases significantly by further increasing annealing duration. The enhanced stripping resistance at the earlier stage might be due to the modifications of microstructure and deformation compatibility of the sprayed coating, while the decreased stripping resistance at the later stage is related to the high stress concentration at the interface of the formed brittle Fe-Al-Zn phase and the Zn-Al coating.

  8. Reply to comment on "Molecular controls on Cu and Zn isotopic fractionation in Fe-Mn crusts"

    NASA Astrophysics Data System (ADS)

    Sherman, David M.; Little, Susan H.; Vance, Derek

    2015-02-01

    In our paper "Molecular controls on Cu and Zn isotopic fractionation in Fe-Mn crusts", we present an explanation for the observed isotopic fractionations of Cu and Zn in seawater. We hypothesise that the isotopic fractionation of Cu and Zn is driven by the scavenging of these metals by particulate Fe-Mn oxides as reflected in the isotopic composition of Zn and Cu in marine ferromanganese crusts. Zn sorbed to ferromanganese crusts is isotopically heavier than dissolved Zn in seawater by 0.5‰. EXAFS spectra show that Zn in ferromanganese crusts is sorbed to birnessite and in tetrahedral coordination. Dissolved inorganic Zn in seawater, however, is primarily octahedrally coordinated as Zn(H2O)+26. The difference in the Zn coordination environment gives a qualitative explanation for the sorption (scavenging) of isotopically heavy Zn by ferromanganese crusts (predominantly birnessite).

  9. Ferromagnetic behaviour of Fe-doped ZnO nanograined films

    PubMed Central

    Protasova, Svetlana G; Mazilkin, Andrei A; Tietze, Thomas; Goering, Eberhard; Schütz, Gisela; Straumal, Petr B; Baretzky, Brigitte

    2013-01-01

    Summary The influence of the grain boundary (GB) specific area s GB on the appearance of ferromagnetism in Fe-doped ZnO has been analysed. A review of numerous research contributions from the literature on the origin of the ferromagnetic behaviour of Fe-doped ZnO is given. An empirical correlation has been found that the value of the specific grain boundary area s GB is the main factor controlling such behaviour. The Fe-doped ZnO becomes ferromagnetic only if it contains enough GBs, i.e., if s GB is higher than a certain threshold value s th = 5 × 104 m2/m3. It corresponds to the effective grain size of about 40 μm assuming a full, dense material and equiaxial grains. Magnetic properties of ZnO dense nanograined thin films doped with iron (0 to 40 atom %) have been investigated. The films were deposited by using the wet chemistry “liquid ceramics” method. The samples demonstrate ferromagnetic behaviour with J s up to 0.10 emu/g (0.025 μB/f.u.ZnO) and coercivity H c ≈ 0.03 T. Saturation magnetisation depends nonmonotonically on the Fe concentration. The dependence on Fe content can be explained by the changes in the structure and contiguity of a ferromagnetic “grain boundary foam” responsible for the magnetic properties of pure and doped ZnO. PMID:23844341

  10. Corrosion resistance of Nd-Fe-B sintered magnets with intergranular addition of Cu 60Zn 40 powders

    NASA Astrophysics Data System (ADS)

    Wu, Yeren; Ni, Junjie; Ma, Tianyu; Yan, Mi

    2010-08-01

    Cu 60Zn 40 powders, as grain boundary modifiers, were added into Nd 28.2Dy 2.0Fe balAl 0.1Nb 0.2Ga 0.11B 0.96 sintered magnets to improve the corrosion resistance of magnets. The corrosion resistance of magnets was investigated by polarization curve measurements in 3.5 wt% NaCl and 3.0 wt% NaOH solutions. It was found that the Cu 60Zn 40-added magnets had more positive corrosion potential Ecorr and much lower corrosion current density icorr than the Cu 60Zn 40-free one in both solutions, indicating the improvement of the corrosion resistance by Cu 60Zn 40 intergranular addition. Promotion of the electrochemical potential of the intergranular phase, formation of the Nd (Fe, Cu) 2 phase, the uniform distribution of the Nd-rich phase and increase of the magnet density were found to be responsible for the improvement of the corrosion resistance.

  11. Hydrothermal synthesis of Fe2O3/ZnO heterojunction photoanode for photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Chen, Chao; Bai, Hongye; da, Zulin; Li, Meng; Yan, Xu; Jiang, Jinhui; Fan, Weiqiang; Shi, Weidong

    2015-05-01

    We report a photoanode based on Fe2O3/zinc oxide (ZnO) heterojunction synthesized by hydrothermal method for photoelectrochemical (PEC) water splitting. The forming heterojunction is systemically characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results from the I-V characteristic curve and conversation efficiency of Fe2O3/ZnO heterojunction reveal that the forming heterojunction would be a benefit for electron transferring from conduction band of ZnO to that of Fe2O3. However, the quantity of ZnO film has an effect on the photocurrent density, the suitable of which has shown enhanced PEC performance.

  12. Processing and properties of FeAl-bonded composites

    SciTech Connect

    Schneibel, J.H.; Subramanian, R.; Alexander, K.B.; Becher, P.F.

    1996-12-31

    Iron aluminides are thermodynamically compatible with a wide range of ceramics such as carbides, borides, oxides, and nitrides, which makes them suitable as the matrix in composites or cermets containing fine ceramic particulates. For ceramic contents varying from 30 to 60 vol.%, composites of Fe-40 at. % Al with WC, TiC, TiB{sub 2}, and ZrB{sub 2} were fabricated by conventional liquid phase sintering of powder mixtures. For ceramic contents from 70 to 85 vol.%, pressureless melt infiltration was found to be a more suitable processing technique. In FeAl-60 vol.% WC, flexure strengths of up to 1.8 GPa were obtained, even though processing defects consisting of small oxide clusters were present. Room temperature fracture toughnesses were determined by flexure testing of chevron-notched specimens. FeAl/WC and FeAl/TiC composites containing 60 vol.% carbide particles exhibited K{sub Q} values around 20 MPa m{sup 1/2}. Slow crack growth measurements carried out in water and in dry oxygen suggest a relatively small influence of water-vapor embrittlement. It appears therefore that the mechanical properties of iron aluminides in the form of fine ligaments are quite different from their bulk properties. Measurements of the oxidation resistance, dry wear resistance, and thermal expansion of iron aluminide composites suggest many potential applications for these new materials.

  13. Highly-oriented Fe2O3/ZnFe2O4 nanocolumnar heterojunction with improved charge separation for photoelectrochemical water oxidation.

    PubMed

    Luo, Zhibin; Li, Chengcheng; Zhang, Dong; Wang, Tuo; Gong, Jinlong

    2016-07-12

    This paper describes the design and synthesis of a heterojunction photoanode composed of highly-oriented Fe2O3/ZnFe2O4 nanocolumnar arrays with a well-defined morphology by reactive ballistic deposition and atomic layer deposition. This specific structure enhances the charge separation at the Fe2O3/ZnFe2O4 interface, leading to an improved photoelectrochemical performance for water oxidation. PMID:26696447

  14. Carbon Nanostructures Grown on Fe-Cr-Al Alloy

    NASA Astrophysics Data System (ADS)

    Čaplovičová, Mária; Čaplovič, Ľubomír; Búc, Dalibor; Vinduška, Peter; Janík, Ján

    2010-11-01

    The morphology and nanostructure of carbon nanotubes (CNTs), synthesized directly on Fe-Cr-Al-based alloy substrate using an alcohol catalytic chemical vapour deposition method (ACCVD), were examined by transmission electron microscopy (TEM). The grown CNTs were entangled with chain-like, bamboo-like, and necklace-like morphologies. The CNT morphology was affected by the elemental composition of catalysts and local instability of deposition process. Straight and bended CNTs with bamboo-like nanostructure grew mainly on γ-Fe and Fe3C particles. The synthesis of necklace-like nanostructures was influenced by silicon oxide, and growth of chain-like nanostructures was supported by a catalysts consisting of Fe, Si, oxygen and trace of Cr. Most of nanotubes grew according to base growth mechanism.

  15. Development of ODS-Fe{sub 3}Al alloys

    SciTech Connect

    Wright, I.G.; Pint, B.A.; Tortorelli, P.F.; McKamey, C.G.

    1997-12-01

    The overall goal of this program is to develop an oxide dispersion-strengthened (ODS) version of Fe{sub 3}Al that has sufficient creep strength and resistance to oxidation at temperatures in the range 1000 to 1200 C to be suitable for application as heat exchanger tubing in advanced power generation cycles. The main areas being addressed are: (a) alloy processing to achieve the desired alloy grain size and shape, and (b) optimization of the oxidation behavior to provide increased service life compared to semi-commercial ODS-FeCrAl alloys intended for the same applications. The recent studies have focused on mechanically-alloyed powder from a commercial alloy vendor. These starting alloy powders were very clean in terms of oxygen content compared to ORNL-produced powders, but contained similar levels of carbon picked up during the milling process. The specific environment used in milling the powder appears to exert a considerable influence on the post-consolidation recrystallization behavior of the alloy. A milling environment which produced powder particles having a high surface carbon content resulted in a consolidated alloy which readily recrystallized, whereas powder with a low surface carbon level after milling resulted in no recrystallization even at 1380 C. A feature of these alloys was the appearance of voids or porosity after the recrystallization anneal, as had been found with ORNL-produced alloys. Adjustment of the recrystallization parameters did not reveal any range of conditions where recrystallization could be accomplished without the formation of voids. Initial creep tests of specimens of the recrystallized alloys indicated a significant increase in creep strength compared to cast or wrought Fe{sub 3}Al, but the specimens failed prematurely by a mechanism that involved brittle fracture of one of the two grains in the test cross section, followed by ductile fracture of the remaining grain. The reasons for this behavior are not yet understood. The

  16. Composition and solidification microstructure selection in the interdendritic matrix between primary Al{sub 3}Fe dendrites in hypereutectic Al-Fe alloys

    SciTech Connect

    Liang, D.; Korgul, P.; Jones, H.

    1996-07-01

    The composition and constitution of matrix microstructure between plate-like Al{sub 3}Fe dendrites in Bridgman-grown hypereutectic Al-Fe alloys has been determined as a function of alloy concentration C{sub 0} and growth velocity V in the ranges 2.5 < C{sub 0} < 28.1 wt%Fe and 0.01 < V < 5.0 mm/s. The transition at V = 0.1 mm/s from a fully eutectic matrix at C{sub 0} = 3.5 wt%Fe to one containing {alpha}Al dendrites at C{sub 0} {ge} 4.7 wt%Fe is attributed to growth temperatures of {alpha}Al dendrites that are higher than those of eutectic in a matrix of lower iron-content, which results from these conditions. The matrix eutectic changes from irregular {alpha}-Al-Al{sub 3}Fe to regular {alpha}Al-Al{sub x}Fe with increasing V, the transition velocity increasing from 0.1 to 0.2 mm/s for C{sub 0} values of 9.5 and 14 wt%Fe up to 0.35--1.0 mm/s for C{sub 0} values of 18.7--28.1 wt%Fe. This increased transition velocity, compared with that for {alpha}-Al-Al{sub 3}Fe to {alpha}Al-Al{sub 6}Fe at lower concentration, is indicative of a lower formation temperature for the {alpha}Al-Al{sub x}Fe than the {alpha}Al-Al{sub 6}Fe eutectic.

  17. Study on the Electrochemical Reaction Mechanism of ZnFe2O4 by In Situ Transmission Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Su, Qingmei; Wang, Shixin; Yao, Libing; Li, Haojie; Du, Gaohui; Ye, Huiqun; Fang, Yunzhang

    2016-06-01

    A family of mixed transition–metal oxides (MTMOs) has great potential for applications as anodes for lithium ion batteries (LIBs). However, the reaction mechanism of MTMOs anodes during lithiation/delithiation is remain unclear. Here, the lithiation/delithiation processes of ZnFe2O4 nanoparticles are observed dynamically using in situ transmission electron microscopy (TEM). Our results suggest that during the first lithiation process the ZnFe2O4 nanoparticles undergo a conversion process and generate a composite structure of 1–3 nm Fe and Zn nanograins within Li2O matrix. During the delithiation process, volume contraction and the conversion of Zn and Fe take place with the disappearance of Li2O, followed by the complete conversion to Fe2O3 and ZnO not the original phase ZnFe2O4. The following cycles are dominated by the full reversible phase conversion between Zn, Fe and ZnO, Fe2O3. The Fe valence evolution during cycles evidenced by electron energy–loss spectroscopy (EELS) techniques also exhibit the reversible conversion between Fe and Fe2O3 after the first lithiation, agreeing well with the in situ TEM results. Such in situ TEM observations provide valuable phenomenological insights into electrochemical reaction of MTMOs, which may help to optimize the composition of anode materials for further improved electrochemical performance.

  18. Study on the Electrochemical Reaction Mechanism of ZnFe2O4 by In Situ Transmission Electron Microscopy.

    PubMed

    Su, Qingmei; Wang, Shixin; Yao, Libing; Li, Haojie; Du, Gaohui; Ye, Huiqun; Fang, Yunzhang

    2016-01-01

    A family of mixed transition-metal oxides (MTMOs) has great potential for applications as anodes for lithium ion batteries (LIBs). However, the reaction mechanism of MTMOs anodes during lithiation/delithiation is remain unclear. Here, the lithiation/delithiation processes of ZnFe2O4 nanoparticles are observed dynamically using in situ transmission electron microscopy (TEM). Our results suggest that during the first lithiation process the ZnFe2O4 nanoparticles undergo a conversion process and generate a composite structure of 1-3 nm Fe and Zn nanograins within Li2O matrix. During the delithiation process, volume contraction and the conversion of Zn and Fe take place with the disappearance of Li2O, followed by the complete conversion to Fe2O3 and ZnO not the original phase ZnFe2O4. The following cycles are dominated by the full reversible phase conversion between Zn, Fe and ZnO, Fe2O3. The Fe valence evolution during cycles evidenced by electron energy-loss spectroscopy (EELS) techniques also exhibit the reversible conversion between Fe and Fe2O3 after the first lithiation, agreeing well with the in situ TEM results. Such in situ TEM observations provide valuable phenomenological insights into electrochemical reaction of MTMOs, which may help to optimize the composition of anode materials for further improved electrochemical performance. PMID:27306189

  19. Study on the Electrochemical Reaction Mechanism of ZnFe2O4 by In Situ Transmission Electron Microscopy

    PubMed Central

    Su, Qingmei; Wang, Shixin; Yao, Libing; Li, Haojie; Du, Gaohui; Ye, Huiqun; Fang, Yunzhang

    2016-01-01

    A family of mixed transition–metal oxides (MTMOs) has great potential for applications as anodes for lithium ion batteries (LIBs). However, the reaction mechanism of MTMOs anodes during lithiation/delithiation is remain unclear. Here, the lithiation/delithiation processes of ZnFe2O4 nanoparticles are observed dynamically using in situ transmission electron microscopy (TEM). Our results suggest that during the first lithiation process the ZnFe2O4 nanoparticles undergo a conversion process and generate a composite structure of 1–3 nm Fe and Zn nanograins within Li2O matrix. During the delithiation process, volume contraction and the conversion of Zn and Fe take place with the disappearance of Li2O, followed by the complete conversion to Fe2O3 and ZnO not the original phase ZnFe2O4. The following cycles are dominated by the full reversible phase conversion between Zn, Fe and ZnO, Fe2O3. The Fe valence evolution during cycles evidenced by electron energy–loss spectroscopy (EELS) techniques also exhibit the reversible conversion between Fe and Fe2O3 after the first lithiation, agreeing well with the in situ TEM results. Such in situ TEM observations provide valuable phenomenological insights into electrochemical reaction of MTMOs, which may help to optimize the composition of anode materials for further improved electrochemical performance. PMID:27306189

  20. Low cycle fatigue of FeAl(42 at. % Al) at room temperature

    SciTech Connect

    Hanes, D.B.; Gibala, R.

    1997-12-31

    The monotonic mechanical behavior in tension and compression of FeAl has been well documented. However, very little work has been done on the cyclic deformation behavior of this material. In this work, the behavior of FeAl (42 at. % Al) under low cycle fatigue was studied, including the effects of test environments and surface coatings. It was found that the fatigue life of this alloy is limited by environmental embrittlement. This embrittlement process can be equally well prevented by deformation in an oxygen environment or by coating the alloy with a protective film. The type of film applied appears to have little effect. Similar results were seen in monotonic testing.

  1. Fabrication and Electrical Characterization of the Si/ZnO/ZnO:Al Structure Deposited by RF-Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Alaya, A.; Djessas, K.; El Mir, L.; Khirouni, K.

    2016-06-01

    The electrical transport properties of the structures of Si(p)/ZnO(i)/ZnO: Al(3%) and Si(p)/PS/ZnO(i)/ZnO: Al(3%) deposited by radio-frequency-magnetron sputtering were investigated and compared by using current-voltage and impedance spectroscopy measurements in a wide temperature range of 80-300 K. Aluminum-doped ZnO is considered to be one of the most important transparent conducting oxide materials due to its high conductivity, good transparency and low cost. From the current-voltage-temperature (I-V-T) characteristics, it was found that both structures had a good rectifying behavior. This behavior decreases according to the porous silicon layer. The variation of the conductance with frequency indicates the semiconducting behavior and superposition of different conduction mechanisms. The insertion of the porous silicon layer results in a decrease of conductivity, which is attributed to reduced conductivity of defect-rich porous silicon.

  2. Low substrate temperature deposition of transparent and conducting ZnO:Al thin films by RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Waykar, Ravindra; Amit, Pawbake; Kulkarni, Rupali; Jadhavar, Ashok; Funde, Adinath; Waman, Vaishali; Dewan, Rupesh; Pathan, Habib; Jadkar, Sandesh

    2016-04-01

    Transparent and conducting Al-doped ZnO (ZnO:Al) films were prepared on glass substrate using the RF sputtering method at different substrate temperatures from room temperature (RT) to 200 °C. The structural, morphological, electrical and optical properties of these films were investigated using a variety of characterization techniques such as low angle XRD, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), Hall measurement and UV–visible spectroscopy. The electrical properties showed that films deposited at RT have the lowest resistivity and it increases with an increase in the substrate temperature whereas carrier mobility and concentration decrease with an increase in substrate temperature. Low angle XRD and Raman spectroscopy analysis reavealed that films are highly crystalline with a hexagonal wurtzite structure and a preferred orientation along the c-axis. The FE-SEM analysis showed that the surface morphology of films is strongly dependent on the substrate temperature. The band gap decreases from 3.36 to 3.29 eV as the substrate temperature is increased from RT to 200 °C. The fundamental absorption edge in the UV region shifts towards a longer wavelength with an increase in substrate temperature and be attributed to the Burstein-Moss shift. The synthesized films showed an average transmission (> 85%) in the visible region, which signifies that synthesized ZnO:Al films can be suitable for display devices and solar cells as transparent electrodes.

  3. Photocatalytic activity of non-stoichiometric ZnFe2O4 under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Šutka, A.; Pärna, R.; Kleperis, J.; Käämbre, T.; Pavlovska, I.; Korsaks, V.; Malnieks, K.; Grinberga, L.; Kisand, V.

    2014-04-01

    Nanostructured zinc ferrites with different excess iron contents (ZnFe2+zO4, where z = 0.00, 0.05, 0.10 and 0.15) have been synthesized using the sol-gel auto-combustion method. The effect of excess iron on the structural, optical and visible light photocatalytic activity of zinc ferrite samples has been investigated. X-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), x-ray magnetic circular dichroism (XMCD), Brunauer-Emmett-Teller theory, scanning electron microscopy (SEM), diffuse reflectance spectroscopy (UV-Vis) and photoluminescence spectroscopy were used to characterize the synthesized non-stoichiometric ZnFe2O4 powders. The XRD patterns demonstrated that the samples consist of single phase spinel structure with crystallite sizes of ˜25 nm. SEM analysis indicated that the nanosized particles grow together in porous clusters with a size of several microns. The XPS and XMCD analyses revealed that the excess iron ion substitutes Zn2+ in tetrahedral sites and in octahedral sites Fe2+ can be found in addition to Fe3+, which could be created to restore the overall charge balance in the crystal lattice. Stoichiometric zinc ferrite (ZnFe2+zO4, z = 0.00) exhibited higher photocatalytic activity (40%) than the excess iron sample (ZnFe2+zO4, z = 0.15, i.e. 4%) under visible light irradiation for 3 h. This was explained by the formation of Fe2+ in the octahedral sites of excess iron ZnFe2O4; these species act as recombination centres.

  4. Comparison of metals extractability from Al/Fe-based drinking water treatment residuals.

    PubMed

    Wang, Changhui; Bai, Leilei; Pei, Yuansheng; Wendling, Laura A

    2014-12-01

    Recycling of drinking water treatment residuals (WTRs) as environment amendments has attracted substantial interest due to their productive reuse concomitant with waste minimization. In the present study, the extractability of metals within six Al/Fe-hydroxide-comprised WTRs collected throughout China was investigated using fractionation, in vitro digestion and the toxicity characteristic leaching procedure (TCLP). The results suggested that the major components and structure of the WTRs investigated were similar. The WTRs were enriched in Al, Fe, Ca, and Mg, also contained varying quantities of As, Ba, Be, Cd, Co, Cr, Cu, K, Mn, Mo, Na, Ni, Pb, Sr, V, and Zn, but Ag, Hg, Sb, and Se were not detected. Most of the metals within the WTRs were largely non-extractable using the European Community Bureau of Reference (BCR) procedure, but many metals exhibited high bioaccessibility based on in vitro digestion. However, the WTRs could be classified as non-hazardous according to the TCLP assessment method used by the US Environmental Protection Agency (USEPA). Further analysis showed the communication factor, which is calculated as the ratio of total extractable metal by BCR procedure to the total metal, for most metals in the six WTRs, was similar, whereas the factor for Ba, Mn, Sr, and Zn varied substantially. Moreover, metals in the WTRs investigated had different risk assessment code. In summary, recycling of WTRs is subject to regulation based on assessment of risk due to metals prior to practical application. PMID:25023656

  5. High noise suppression using magnetically isotropic (CoFe-AlN)/(AlN) multilayer films

    NASA Astrophysics Data System (ADS)

    Kijima, Hanae; Ohnuma, Shigehiro; Masumoto, Hiroshi; Shimada, Yutaka; Endo, Yasushi; Yamaguchi, Masahiro

    2015-05-01

    Magnetically isotropic (CoFe-AlN)n/(AlN)n+1 multilayer films, in which the number of CoFe-AlN magnetic layers n ranged from 1 to 27, were prepared by radio frequency sputtering to achieve noise suppression at gigahertz frequencies. The soft CoFe-AlN magnetic layers consisted of nanometer-sized CoFe ferromagnetic grains embedded in an insulating AlN amorphous matrix, while the insulating AlN layers comprised AlN columnar crystals. All films showed a similar frequency dependence of permeability and ferromagnetic resonance of 1.7 GHz. Noise suppression was evaluated using a microstrip line as a noise source by determining the in-line conductive loss and the near-field intensity picked up by magnetic field detective probes. High noise suppression effects were observed in every direction in the film plane. Maximum noise suppression values amounted to 60% for the in-line conductive loss and -20 dB for the magnetic near-field intensity at around 1.7 GHz in the 27-layer film. These high-frequency noise suppression levels may be attributed to eddy current losses and ferromagnetic resonance.

  6. Corrosion performance of Fe-Cr-Al and Fe aluminide alloys in complex gas environments

    SciTech Connect

    Natesan, K.; Johnson, R.N.

    1995-05-01

    Alumina-forming structural alloys can offer superior resistance to corrosion in the presence of sulfur-containing environments, which are prevalent in coal-fired fossil energy systems. Further, Fe aluminides are being developed for use as structural materials and/or cladding alloys in these systems. Extensive development has been in progress on Fe{sub 3}Al-based alloys to improve their engineering ductility. In addition, surface coatings of Fe aluminide are being developed to impart corrosion resistance to structural alloys. This paper describes results from an ongoing program that is evaluating the corrosion performance of alumina-forming structural alloys, Fe-Al and Fe aluminide bulk alloys, and Fe aluminide coatings in environments typical of coal-gasification and combustion atmospheres. Experiments were conducted at 650-1000{degrees}C in simulated oxygen/sulfur gas mixtures. Other aspects of the program are corrosion evaluation of the aluminides in the presence of HCl-containing gases. Results are used to establish threshold Al levels in the alloys for development of protective alumina scales and to determine the modes of corrosion degradation that occur in the materials when they are exposed to S/Cl-containing gaseous environments.

  7. Positron lifetime studies of decomposition in 2024 (Al-Cu-Mg) and 7010 (Al-Zn-Cu-Mg) alloys

    SciTech Connect

    Dlubek, G. |; Lademann, P.; Krause, H.; Krause, S.; Unger, R.

    1998-09-04

    In the current paper, the decomposition behavior of the engineering alloys 2024 (Al-Cu-Mg) and 7010 (Al-Zn-Cu-Mg) is studied using positron lifetime measurements. Positrons probe open volume defects such as vacancies and dislocations. However, they may also be used to investigate coherent zones and incoherent precipitates. In order to understand the rather complicated precipitation sequences and the response of positrons to different type of precipitates occurring in 2024 and 7010 alloys, binary and ternary laboratory alloys were also investigated under the same experimental conditions as the engineering alloys. The interpretations of the results are based on experiences of the group from extensive positron studies of laboratory alloys such as Al-Zn, Al-Zn-Mg, Al-Cu, and further Al alloys (see also the review (4)). Their collected results are shown as lifetimes and curve-shape parameters S of the electron-positron momentum distribution curves characteristic for different precipitates in Al alloys.

  8. Morphological properties of Al-doped ZnO nano/microstructures

    NASA Astrophysics Data System (ADS)

    Kim, Kyung Ho; Umakoshi, Tomoyuki; Abe, Yoshio; Kawamura, Midori; Kiba, Takayuki

    2016-03-01

    We discussed the morphological properties of Al-doped zinc oxide (Al-ZnO) microrods grown on a ZnO seed layer and precipitation particles and compared them with undoped ZnO samples. The ZnO nanorods grown on a ZnO seed layer were dense and perpendicular to the surface of the substrate, i.e., fluorine-doped tin oxide (FTO). In contrast the Al-ZnO grew as larger microrods, and the rods were sparsely and obliquely arranged. Precipitation particles synthesized in the ZnO solution through homogeneous nucleation had flower-like structures assembled from the rods and individual rods with lengths of several micrometers. Al-ZnO precipitation particles consisted of rods with length of several micrometers and hexagonal nanoplates. Fourier transform infrared (FTIR) analysis results showed that the rods and precipitation particles had the good chemical properties of ZnO. Both size and morphology of the rods could be effectively controlled by adding aluminum nitrate (Al(NO3)3) as dopant in the ZnO rod solution.

  9. Screened moments and absence of ferromagnetism in FeAl

    NASA Astrophysics Data System (ADS)

    Galler, A.; Taranto, C.; Wallerberger, M.; Kaltak, M.; Kresse, G.; Sangiovanni, G.; Toschi, A.; Held, K.

    2015-11-01

    While the stoichiometric intermetallic compound FeAl is found to be paramagnetic in experiment, standard band-theory approaches predict the material to be ferromagnetic. We show that this discrepancy can be overcome by a better treatment of electronic correlations with density-functional plus dynamical mean-field theory. Our results show no ferromagnetism down to 100 K and since the susceptibility is decreasing at the lowest temperatures studied we also do not expect ferromagnetism at even lower temperatures. This behavior is found to originate from temporal quantum fluctuations that screen short-lived local magnetic moments of 1.6 μB on Fe.

  10. Electron transport in Al-doped ZnO nanolayers obtained by atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Blagoev, B. S.; Dimitrov, D. Z.; Mehandzhiev, V. B.; Kovacheva, D.; Terziyska, P.; Pavlic, J.; Lovchinov, K.; Mateev, E.; Leclercq, J.; Sveshtarov, P.

    2016-03-01

    Al-doped ZnO thin films with different Al content were prepared by atomic layer deposition (ALD). To carry out thermal ALD, diethyl zinc (DEZ) and tri-methyl aluminium (TMA) were used as Zn and Al precursors, respectively, and water vapor as oxidant. Various numbers n of DEZ and m TMA cycles was used to obtain different [ZnO] n [Al2O3] m films, where n = 100 – 95, m = 1 – 5. The X-ray diffraction analysis showed a predominantly (100) oriented polycrystalline phase for the ZnO:Al films with a low Al content (m = 1 – 3) and an amorphous structure for pure Al2O3. In ZnO:Al with a higher Al content (m = 4 – 6) the (100) reflection disappeared and the (002) peak increased. The resistivity of the films decreased with the increase in the Al content, reaching a minimum of 3.3×10-3 Ω cm at about 1.1 % Al2O3 for the [ZnO]99[Al2O3]2 sample; for higher dopant concentrations, the resistivity increased because of the increased crystal inhomogeneity due to axis reorientation.

  11. Synthesis and Characterization of Photocatalytic TiO 2 -ZnFe 2 O 4 Nanoparticles

    DOE PAGESBeta

    Srinivasan, Sesha S.; Wade, Jeremy; Stefanakos, Elias K.

    2006-01-01

    A new coprecipimore » tation/hydrolysis synthesis route is used to create a TiO 2 -ZnFe 2 O 4 nanocomposite that is directed towards extending the photoresponse of TiO 2 from UV to visible wavelengths ( > 400   nm ). The effect of TiO 2 's accelerated anatase-rutile phase transformation due to the presence of the coupled ZnFe 2 O 4 narrow-bandgap semiconductor is evaluated. The transformation's dependence on pH, calcinations temperature, particle size, and ZnFe 2 O 4 concentration has been analyzed using XRD, SEM, and UV-visible spectrometry. The requirements for retaining the highly photoactive anatase phase present in a ZnFe 2 O 4 nanocomposite are outlined. The visible-light-activated photocatalytic activity of the TiO 2 -ZnFe 2 O 4 nanocomposites has been compared to an Aldrich TiO 2 reference catalyst, using a solar-simulated photoreactor for the degradation of phenol.« less

  12. Rapid and efficient removal/recovery of molybdenum onto ZnFe2O4 nanoparticles.

    PubMed

    Tu, Yao-Jen; Chan, Ting-Shan; Tu, Hao-Wei; Wang, Shan-Li; You, Chen-Feng; Chang, Chien-Kuei

    2016-04-01

    An efficient method for removing and recovering molybdenum (Mo) from water was developed by using ZnFe2O4 nanoparticles. The Mo adsorption displayed a nonlinear isotherm that fitted well with the Langmuir isotherm, showing limited adsorption sites on the surface of ZnFe2O4. The adsorption of Mo(VI) was dependent on solution pH. With increasing pH, the build-up of negative charges of both adsorbent and adsorbate led to enhanced electric repulsion between them. The K-edge XANES spectra for the adsorbents collected after Mo adsorption revealed that Mo(VI) was the predominant oxidation state sorbed on ZnFe2O4, indicating that the reduction of Mo(VI) did not occur on ZnFe2O4. The different peak positions of k-space and R-space shown in K-edge EXAFS spectra demonstrated that the adsorbed Mo could be bound on the surface or be slipped in the vacancy position of the ZnFe2O4 crystal. Importantly, Mo could be efficiently adsorbed from photoelectric industrial wastewater and these adsorbed Mo anions were rapidly replaced by OH(-) ions, implying the potential for Mo removing and recovering in industrial wastewater. PMID:26835649

  13. Synthesis and characterization of magnetic diphase ZnFe2O4 /γ-Fe2O3 electrospun fibers

    PubMed Central

    Arias, M.; Pantojas, V.M.; Perales, O.; Otaño, W.

    2011-01-01

    Magnetic nanofibers of ZnFe2O4 / γ-Fe2O3 composite were synthesized by electrospinning from a sol-gel solution containing a molar ratio Fe/Zn of 3. The effects of the calcination temperature on the phase composition, particle size and magnetic properties have been investigated. Zinc ferrite fibers were obtained by calcinating the electrospun fibers in air from 300 °C to 800 °C and characterized by thermogravimetric analyses, Fourier transformed infrared spectroscopy, x-ray photoemission spectroscopy, x-ray diffraction, vibration sample magnetometry and magnetic force microscopy. The resulting fibers, with diameters ranging from 90 to 150 nm, were ferrimagnetic with high saturation magnetization as compared to bulk. Increasing the calcination temperature resulted in an increase in particle size and saturation magnetization. The observed increase in saturation magnetization was most likely due to the formation and growth of ZnFe2O4 /γ-Fe2O3 diphase crystals. The highest saturation magnetization (45 emu/g) was obtained for fibers calcined at 800 °C. PMID:21779141

  14. Section 2: Phase transformation studies in mechanically alloyed Fe-Nz and Fe-Zn-Si intermetallics

    SciTech Connect

    Jordan, A.; Uwakweh, O.N.C.; Maziasz, P.J.

    1997-04-01

    The initial stage of this study, which was completed in FY 1995, entailed an extensive analysis characterizing the structural evolution of the Fe-Zn intermetallic system. The primary interest in these Fe-Zn phases stems from the fact that they form an excellent coating for the corrosion protection of steel (i.e., automobile body panels). The Fe-Zn coating generally forms up to four intermetallic phases depending on the particular industrial application used, (i.e., galvanization, galvannealing, etc.). Since the different coating applications are non-equilibrium in nature, it becomes necessary to employ a non-equilibrium method for producing homogeneous alloys in the solid-state to reflect the structural changes occurring in a true coating. This was accomplished through the use of a high energy/non-equilibrium technique known as ball-milling which allowed the authors to monitor the evolution process of the alloys as they transformed from a metastable to stable equilibrium state. In FY 1996, this study was expanded to evaluate the presence of Si in the Fe-Zn system and its influence in the overall coating. The addition of silicon in steel gives rise to an increased coating. However, the mechanisms leading to the coating anomaly are still not fully understood. For this reason, mechanical alloying through ball-milling of pure elemental powders was used to study the structural changes occurring in the sandelin region (i.e., 0.12 wt % Si). Through the identification of invariant reactions (i.e., eutectic, etc.) the authors were able to explore the sandelin phenomenon and also determine the various fields or boundaries associated with the Fe-Zn-Si ternary system.

  15. Enhancement in dielectric behavior of (Ni, Zn)Fe2O4 ferrite

    NASA Astrophysics Data System (ADS)

    Sheikh, Javed R.; Gaikwad, Vishwajit M.; Moon, Vaibhav C.; Acharya, Smita A.

    2016-05-01

    In present work, NiFe2O4(NFO), ZnFe2O4 (ZFO) and Ni0.5Zn0.5Fe2O4 (NZFO) are synthesized by microwave assisted co-precipitation route. Their structural properties are confirmed by X-ray diffraction and data is fitted through Reitveld refinement using Full-Prof software suite. After refinement, the systematic crystal structures of NFO, ZFO and NZFO compounds are generated using output .cif file by VESTA (Visualization for Electronic and Structural Analysis) program. Structural parameters obtained after refinement and unit cell construction, are systematically tabulated. Room temperature frequency dependence dielectric properties are studied. We found enhanced values of dielectric constant for NZFO than individual NFO and ZFO phases. For NZFO sample, greater electron exchange between Fe2+ and Fe3+ which enhances polarization and dielectric constant.

  16. Removal of hexavalent chromium from aqueous solution by calcined Zn/Al-LDHs.

    PubMed

    Yang, Hui-Duo; Zhao, Yun-Peng; Li, Shi-Feng; Fan, Xing; Wei, Xian-Yong; Zong, Zhi-Min

    2016-01-01

    In this study, Zn/Al-layered double hydroxides (Zn/Al-LDHs) were synthesized by a co-precipitation method and characterized with X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. Then the hexavalent chromium Cr(VI) adsorption experiments on calcined Zn/Al-LDHs were carried out to analyze the effects of pH, temperature, adsorption time, initial Cr(VI) concentration and adsorbent dosage on the removal of Cr(VI) from aqueous solutions. The maximum adsorption capacity for Cr(VI) on calcined Zn/Al-LDHs under optimal conditions was found to be over 120 mg/g. The kinetic and isotherm of Cr(VI) adsorption on calcined Zn/Al-LDHs can be described with the pseudo-second-order kinetic model and Langmuir isotherm, respectively. PMID:27387001

  17. Organo/Zn-Al LDH Nanocomposites for Cationic Dye Removal from Aqueous Media

    NASA Astrophysics Data System (ADS)

    Starukh, G.; Rozovik, O.; Oranska, O.

    2016-04-01

    Cationic dye sorption by Zn-Al-layered double hydroxides (LDHs) modified with anionic surfactants was examined using methylene blue (MB) dye as a compound model in aqueous solutions. The modification of Zn-Al LDHs was performed by reconstruction method using dodecyl sulfate anion (DS) solutions. DS contained Zn-Al LDHs were characterized by XRD, FTIR, thermogravimetric, and SEM analysis. The reconstructed organo/Zn-Al LDHs comprise the crystalline phases (DS-intercalated LDHs, hydrotalcite), and the amorphous phase. The intercalation of DS ions into the interlayer galleries and DS adsorption on the surface of the LDHs occurred causing the MB adsorption on the external and its sorption in the internal surfaces of modified LDHs. The presence of DS greatly increased the affinity of organo/Zn-Al LDHs for MB due to hydrophobic interactions between the surfactants and the dye molecules. The optical properties of sorbed MB were studied.

  18. Organo/Zn-Al LDH Nanocomposites for Cationic Dye Removal from Aqueous Media.

    PubMed

    Starukh, G; Rozovik, O; Oranska, O

    2016-12-01

    Cationic dye sorption by Zn-Al-layered double hydroxides (LDHs) modified with anionic surfactants was examined using methylene blue (MB) dye as a compound model in aqueous solutions. The modification of Zn-Al LDHs was performed by reconstruction method using dodecyl sulfate anion (DS) solutions. DS contained Zn-Al LDHs were characterized by XRD, FTIR, thermogravimetric, and SEM analysis. The reconstructed organo/Zn-Al LDHs comprise the crystalline phases (DS-intercalated LDHs, hydrotalcite), and the amorphous phase. The intercalation of DS ions into the interlayer galleries and DS adsorption on the surface of the LDHs occurred causing the MB adsorption on the external and its sorption in the internal surfaces of modified LDHs. The presence of DS greatly increased the affinity of organo/Zn-Al LDHs for MB due to hydrophobic interactions between the surfactants and the dye molecules. The optical properties of sorbed MB were studied. PMID:27119156

  19. Fe solubility, growth mechanism, and luminescence of Fe doped ZnO nanowires and nanorods grown by evaporation-deposition

    NASA Astrophysics Data System (ADS)

    Alemán, Belén; Ortega, Yanicet; García, José Ángel; Fernández, Paloma; Piqueras, Javier

    2011-07-01

    Fe doped ZnO nanowires, nanorods, and urchin-like nanostructures have been grown using an evaporation-deposition method with compacted mixtures of ZnS and Fe2O3 powders, with different Fe contents as precursors. Treatments at 950 °C under argon flow lead to the growth of iron doped nanowires, nanorods, and other nanostructures on the surface of the compacted sample. The incorporation of iron into the nanostructures has been investigated via energy dispersive spectroscopy as well as by cathodoluminescence in a scanning electron microscope and photoluminescence in an optical microscope. The iron content in the structures is limited to the range of 0.5-0.7 at.% and does not depend on the content in the precursor. Bright and dark field imaging and twist contour analysis via transmission electron microscopy support the possibility of a dislocation driven growth of the nanowires.

  20. One-dimensional SrFe12O19/Ni(0.5)Zn(0.5)Fe2O4 composite ferrite nanofibers and enhancement magnetic property.

    PubMed

    Song, Fuzhan; Shen, Xiangqian; Liu, Mingquan; Xiang, Jun

    2011-08-01

    SrFe12O19/Ni(0.5)Zn(0.5)Fe2O4 composite ferrite nanofibers of diameters about 100 nm with mass ratio 1:1 have been prepared by the electrospinning and calcination process. The SrFe12O19/Ni(0.5)Zn(0.5)Fe2O4 composite ferrites are formed after calcined at 700 degrees C for 2 hours. The composite ferrite nanofibers are fabricated from nanosized Ni(0.5)Zn(0.5)Fe2O4 and SrFe12O19 ferrite grains with a uniform phase distribution. The ferrite grain size increases from about 11 to 36 nm for Ni(0.5)Zn(0.5)Fe12O4 and 24 to 56 nm for SrFe12O19 with the calcination temperature increasing from 700 to 1100 degrees C. With the ferrite grain size increasing, the coercivity (Hc) and remanence (Mr) for the SrFe12O19/Ni(0.5)Zn(0.5)Fe2O4 composite ferrite nanofibers initially increase, reaching a maximum value of 118.4 kA/m and 31.5 Am2/kg at the grain size about 40 nm (SrFe12O19) and 24 nm (Ni(0.5)Zn(0.5)Fe2O4) respectively, and then show a reduction tendency with a further increase of the ferrite grain size. The specific saturation magnetization (Msh) of 63.2 Am2/kg for the SrFe12O19/Ni(0.5)Zn(0.5)Fe2O4 composite ferrite nanofibers obtained at 900 degrees C for 2 hours locates between that for the single SrFe12O19 ferrite (48.5 Am2/kg) and the single Ni(0.5)Zn(0.5)Fe2O4 ferrite (69.3 Am2/kg). In particular, the Mr value 31.5 Am2/kg for the SrFe12O19/Ni(0.5)Zn(0.5)Fe2O4 composite ferrite nanofibers is much higher than that for the individual SrFe12O19 (25.9 Am2/kg) and Ni(0.5)Zn(0.5)Fe2O4 ferrite (11.2 Am2/kg). These enhanced magnetic properties for the composite ferrite nanofibers can be attributed to the exchange-coupling interaction in the composite. PMID:22103109

  1. Elastocaloric effect in CuAlZn and CuAlMn shape memory alloys under compression.

    PubMed

    Qian, Suxin; Geng, Yunlong; Wang, Yi; Pillsbury, Thomas E; Hada, Yoshiharu; Yamaguchi, Yuki; Fujimoto, Kenjiro; Hwang, Yunho; Radermacher, Reinhard; Cui, Jun; Yuki, Yoji; Toyotake, Koutaro; Takeuchi, Ichiro

    2016-08-13

    This paper reports the elastocaloric effect of two Cu-based shape memory alloys: Cu68Al16Zn16 (CuAlZn) and Cu73Al15Mn12 (CuAlMn), under compression at ambient temperature. The compression tests were conducted at two different rates to approach isothermal and adiabatic conditions. Upon unloading at a strain rate of 0.1 s(-1) (adiabatic condition) from 4% strain, the highest adiabatic temperature changes (ΔTad) of 4.0 K for CuAlZn and 3.9 K for CuAlMn were obtained. The maximum stress and hysteresis at each strain were compared. The stress at the maximum recoverable strain of 4.0% for CuAlMn was 120 MPa, which is 70% smaller than that of CuAlZn. A smaller hysteresis for the CuAlMn alloy was also obtained, about 70% less compared with the CuAlZn alloy. The latent heat, determined by differential scanning calorimetry, was 4.3 J g(-1) for the CuAlZn alloy and 5.0 J g(-1) for the CuAlMn alloy. Potential coefficients of performance (COPmat) for these two alloys were calculated based on their physical properties of measured latent heat and hysteresis, and a COPmat of approximately 13.3 for CuAlMn was obtained.This article is part of the themed issue 'Taking the temperature of phase transitions in cool materials'. PMID:27402936

  2. High coercivity of melt-spun Sm2Fe15Al2C1.5 compound

    NASA Astrophysics Data System (ADS)

    Zhang, Jun-Xian; Cheng, Zhao-Hua; Shen, Bao-Gen

    1996-04-01

    The magnetic hardening of melt-spun Sm2Fe17Cx was studied and the coercivity of 4.6 kOe for Sm2Fe17C1.5 alloys was reported a few years ago. Recently, we have succeeded in preparing single-phase compounds of Sm2(Fe, M)17Cx (M=Ga, Al, or Si) with high carbon concentration by arc melting. It was found that the substitution of Ga or Al not only facilitated the formation of high carbon concentration rare-earth iron compounds with a 2:17-type structure, but also was very effective in raising the value of the anisotropy field. For example, the sample of Sm2Fe15Al2C1.5 has a saturation magnetization of 110.2 emu/g, a Curie temperature of 576 K, and an anisotropy field of 111 kOe. It is known that melt spinning is an effective means to obtain high coercivity of magnetically hard materials. In this work, the hard magnetic properties of melt-spun Sm2Fe15Al2C1.5 alloys were investigated. It was found that the value of coercivity depends strongly on the quenching rates and an optimum coercivity of 9.4 kOe was obtained at the quenching rate of 20 m/s. X-ray diffraction patterns indicate that the as-quenched ribbons have a phase of the Th2Zn17-type structure. The high coercivity of these as-quenched ribbons originates from the excellent intrinsic magnetic properties of Sm2Fe15Al2C1.5. It can be concluded that the substitution of Al is very effective in raising the coercivity of melt-spun Sm2Fe15Al2C1.5 ribbons.

  3. The effect of Zn on precipitation in Al-Mg-Si alloys

    NASA Astrophysics Data System (ADS)

    Saito, Takeshi; Wenner, Sigurd; Osmundsen, Elisa; Marioara, Calin D.; Andersen, Sigmund J.; Røyset, Jostein; Lefebvre, Williams; Holmestad, Randi

    2014-07-01

    Effects of addition of Zn (up to 1 wt%) on microstructure, precipitate structure and intergranular corrosion (IGC) in an Al-Mg-Si alloys were investigated. During ageing at 185 °C, the alloys showed modest increases in hardness as function of Zn content, corresponding to increased number densities of needle-shaped precipitates in the Al-Mg-Si alloy system. No precipitates of the Al-Zn-Mg alloy system were found. Using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), the Zn atoms were incorporated in the precipitate structures at different atomic sites with various atomic column occupancies. Zn atoms segregated along grain boundaries, forming continuous film. It correlates to high IGC susceptibility when Zn concentration is ~1wt% and the materials in peak-aged condition.

  4. Microstructure selection maps for Al-Fe alloys

    SciTech Connect

    Gilgien, P.; Zryd, A.; Kurz, W.

    1995-09-01

    The solidification microstructures for Al-0.5-4 at.% Fe alloys under constrained growth conditions have been calculated using analytical models of the growth kinetics of dendritic, eutectic and plane front interface morphologies of stable and metastable phases. Laser remelting experiments are carried out on an Al-4 at.% Fe alloy with low beam velocity (10 mm/s) in order to complete previous experimental results on the solidification microstructures obtained at intermediate growth rates by Bridgman experiments and at a high growth rates by rapid laser resolidification. Comparison of predicted with experimentally determined solidification microstructure maps shows satisfactory agreement in view of the limited knowledge of the thermophysical properties of this system. These maps are useful for the interpretation of microstructures and phases forming under medium to high solidification rates and for the understanding and development of rapid solidification processing. Further the modeling is useful for improving available phase diagram information.

  5. In Vitro Evaluation of Cu, Fe, and Zn Bioaccessibility in the Presence of Babassu Mesocarp.

    PubMed

    Fioroto, Alexandre Minami; Nascimento, Angerson Nogueria; Oliveira, Pedro Vitoriano

    2015-07-22

    In vitro gastrointestinal digestion of babassu mesocarp in the absence and presence of milk and lignin was performed to evaluate the bioaccessibility of Cu, Fe, and Zn. Extractions using NaOH solutions (pH 7 and 12) were carried out to evaluate the interactions of Cu(II), Fe(III), and Zn(II) with the extracted compounds and with the washed mesocarp. Studies using reference solutions showed a decrease in the free concentration of the elements in the presence of mesocarp. Phytate, a component present in the mesocarp, can be the main compound responsible for the elements' interactions with mesocarp. Lignin increases the elements' soluble fractions; however, the elements' concentrations in the dialyzed fractions, representing the bioaccessible portion, were very low. On the other hand, Cu, Fe, and Zn bioaccessibility in milk was not influenced by the mesocarp. PMID:26134249

  6. The effect of coarse second phase particles on fatigue crack propagation of an Al-Zn-Mg-Cu alloy

    SciTech Connect

    Guerbuez, R.; Alpay, S.P. . Dept. of Metallurgical Engineering)

    1994-06-01

    The objective of this study is to determine the role of the most commonly observed coarse second phase particles; Al[sub 7]Cu[sub 2]Fe, Mg[sub 2]Si and CuAl[sub 2]Mg on the Stage 2 fatigue crack propagation of a 7050 aluminum alloy. The differences in the composition of this alloy when compared to the conventional 7075 alloy are: (1) increased Cu content for additional strengthening during aging and for increasing the temperature range of GP zone stability; (2) replacement of Cr by Zr to reduce quench sensitivity; (3) reduced Fe and Si contents to improve fracture toughness which, however, decreases fatigue crack growth threshold, [Delta]K[sub th], slightly; and (4) increased Zn content for strengthening.

  7. Low-frequency alternative-current magnetic susceptibility, photoelectric properties, and adhesive properties of Ni80Fe20 (XÅ)/ZnO(500Å) and ZnO(500Å)/Ni80Fe20(YÅ) on glass substrate

    NASA Astrophysics Data System (ADS)

    Chen, Yuan-Tsung

    2015-08-01

    The following conditions are deposited: (a) glass/Ni80Fe20(XÅ)/ZnO(500Å) and (b) glass/ZnO(500Å)/Ni80Fe20(YÅ), where each of X and Y is 1000Å, 1500Å, 2000Å or 2500Å. The substrate temperature was maintained at room temperature (RT), and post-annealing was performed with heating at (TA) = 150 °C for 1 h or (TA) = 250 °C for 1 h. The sputtering sequence and the thickness of the NiFe film were varied to study the effects of these factors on the low-frequency alternative-current magnetic susceptibility (χac), maximum χac with corresponding optimal resonance frequency (fres), transmission, electrical resistivity (ρ), and surface energy of the multilayered glass/Ni80Fe20(XÅ)/ZnO(500Å) and glass/ZnO(500Å)/Ni80Fe20(YÅ). Experimental results demonstrate that ZnO(500Å)/Ni80Fe20(YÅ) is superior to Ni80Fe20/ZnO(500Å) because diffraction from the ZnO (0 0 2) crystals at the bottom of ZnO(500Å)/Ni80Fe20(YÅ) improves the magneto crystalline anisotropy of Ni80Fe20, improving its magnetic and photoelectrical properties. X-ray diffraction patterns (XRD) reveal that the ZnO (0 0 2), ZnO (2 2 0), and NiFe (1 1 1) peaks of ZnO(500Å)/Ni80Fe20(YÅ) are more intense than those of Ni80Fe20/ZnO(500Å) under three substrate conditions, indicating the ZnO (0 0 2) peak reflects magneto crystalline anisotropy in the crystalline NiFe layer of ZnO(500Å)/Ni80Fe20(YÅ), yielding the highest χac of approximately 3.16 with an fres of 250 Hz upon post-annealing TA = 250 °C for 1 h. The (1 1 1) diffracted intensity and grain size of the thicker and post-annealed Ni80Fe20 thin films exceeded those of the thinner and as-deposited Ni80Fe20 thin films. A spectral analyzer was used to measure transmittance through NiFe of various thicknesses. The transmittance declined slightly as the thickness and grain size increased, because increasing thickness reduced penetration. Post-annealing promoted grain growth, increased the average size of the grains and reduced transmittance. Both as

  8. Tensile properties of Fe-16 at. % Al alloys

    SciTech Connect

    Sikka, V.K.

    1995-02-01

    A newly developed melting method for Fe-16 at. % Al alloy (FAPY) is described. Tensile data on the air-induction-melted (AIM) and vacuum-induction-melted (VIM) heats of FAPY after identical processing are presented. Optical, scanning electron micrographs (SEM), and microprobe analysis were carried out to explain the lower room-temperature ductility and more scatter in the data for the AIM material as opposed to the VIM material.

  9. Synthesis and characterization of Co2FeAl nanowires

    NASA Astrophysics Data System (ADS)

    Sapkota, Keshab R.; Gyawali, Parshu; Forbes, Andrew; Pegg, Ian L.; Philip, John

    2012-06-01

    We report the growth and characterization of Co2FeAl nanowires. Nanowires are grown using electrospinning method and the diameters range from 50 to 500 nm. These nanowires exhibit cubic crystal structure with a lattice constant of a =5.639 Å. The nanowires exhibit ferromagnetic behavior with a very high Curie temperature. The temperature dependent magnetization behavior displays an anomaly in the temperature range 600-850 K, which disappears at higher external magnetic fields.

  10. Zn-Al-rich chlorite in interleaved phyllosilicate grains from the low-temperature metamorphic Ordovician terrane of Iglesiente, south-west Sardinia, Italy

    NASA Astrophysics Data System (ADS)

    Cruciani, Gabriele; Franceschelli, Marcello; Battaglia, Stefano; Pasci, Sandro; Puxeddu, Mariano

    2015-12-01

    Zn-Al chlorite with a ZnO content of 2-3 wt% has been found in the Monte Argentu Formation that belongs to the external zone of the Variscan Sardinian Belt in SW Sardinia. This chlorite occurs in metasiltite rocks characterized by the alternation of dark-coloured layers rich in Fe- and Ti-oxides and light-coloured layers rich in quartz and phyllosilicates. The Zn-Al chlorite is associated with K-white mica, pyrophyllite, and quartz. The most common interleavings consist of K-white mica + Zn-Al chlorite, K-white mica + pyrophyllite, K-white mica + Zn-Al chlorite + pyrophyllite, and Zn-Al chlorite + pyrophyllite. The X-ray patterns of the <2 μm fraction of the investigated samples are characterized by peaks for illite, pyrophyllite, chlorite and quartz. Metamorphic temperatures of 300°-400°C have been estimated on the basis of the pyrophyllite occurrence. Pressure estimated on the basis of K-white mica composition is in the 0.3-0.6 GPa range.

  11. Structure, molecular simulation, and release of aspirin from intercalated Zn-Al-layered double hydroxides.

    PubMed

    Meng, Zilin; Li, Xiaowei; Lv, Fengzhu; Zhang, Qian; Chu, Paul K; Zhang, Yihe

    2015-11-01

    Aspirin or acetylsalicylic acid (AA), a non-steroidal anti-inflammatory drug, is intercalated into Zn-Al-layered double hydroxides (ZnAl-LDHs) by co-precipitation and reconstruction methods. The composition, structure, and morphology of the intercalated products as well as their release behavior are determined experimentally and theoretically by Material Studio 5.5. Experimental results disclose the strong interaction between the LDHs sheets and AA in the intercalated ZnAl-LDHs produced by co-precipitation and slow release of AA from the intercalated ZnAl-LDHs in both phosphate buffered saline (PBS) and borate buffered saline (BBS) solutions. The percentage of AA released from the ZnAl-LDHs prepared by both methods in PBS (96.87% and 98.12%) are much more than those in BBS (68.59% and 81.22%) implying that both H4BO4(-) and H2PO4(-) can exchange with AA in the ZnAl-LDHs. After AA is released to PBS, ZnAl-LDHs break into small pieces. The experimental results are explained theoretically based on the calculation of the bonding energy between the anions and LDHs sheets as well as the AlO bond length change in the LDHs sheets. PMID:26263219

  12. Atomic layer deposition of Al-doped ZnO thin films

    SciTech Connect

    Tynell, Tommi; Yamauchi, Hisao; Karppinen, Maarit; Okazaki, Ryuji; Terasaki, Ichiro

    2013-01-15

    Atomic layer deposition has been used to fabricate thin films of aluminum-doped ZnO by depositing interspersed layers of ZnO and Al{sub 2}O{sub 3} on borosilicate glass substrates. The growth characteristics of the films have been investigated through x-ray diffraction, x-ray reflection, and x-ray fluorescence measurements, and the efficacy of the Al doping has been evaluated through optical reflectivity and Seebeck coefficient measurements. The Al doping is found to affect the carrier density of ZnO up to a nominal Al dopant content of 5 at. %. At nominal Al doping levels of 10 at. % and higher, the structure of the films is found to be strongly affected by the Al{sub 2}O{sub 3} phase and no further carrier doping of ZnO is observed.

  13. Different magnetic origins of (Mn, Fe)-codoped ZnO powders and thin films

    SciTech Connect

    Fan, Jiuping; Jiang, Fengxian; Quan, Zhiyong; Qing, Xiufang; Xu, Xiaohong

    2012-11-15

    Graphical abstract: The effects of the sample forms, fabricated methods, and process conditions on the structural and magnetic properties of (Mn, Fe)-codoped ZnO powders and films were systematically studied. The origins of ferromagnetism in the vacuum-annealed powder and PLD-deposited film are different. The former originates from the impurities of magnetic clusters, whereas the latter comes from the almost homogenous phase. Highlights: ► The magnetic natures of Zn{sub 0.98}Mn{sub 0.01}Fe{sub 0.01}O powders and thin films come from different origins. ► The ferromagnetism of the powder is mainly from the contribution of magnetic clusters. ► Whereas the ferromagnetic behavior of the film comes from the almost homogenous phase. -- Abstract: The structural and magnetic properties of (Mn, Fe)-codoped ZnO powders as well as thin films were investigated. The X-ray diffraction and magnetic measurements indicated that the higher sintering temperature facilitates more Mn and Fe incorporation into ZnO. Magnetic measurements indicated that the powder sintered in air at 800 °C showed paramagnetic, but it exhibited obvious room temperature ferromagnetism after vacuum annealing at 600 °C. The results revealed that magnetic clusters were the major contributors to the observed ferromagnetism in vacuum-annealed Zn{sub 0.98}Mn{sub 0.01}Fe{sub 0.01}O powder. Interestingly, the room temperature ferromagnetism was also observed in the Zn{sub 0.98}Mn{sub 0.01}Fe{sub 0.01}O film deposited via pulsed laser deposition from the air-sintered paramagnetic target, but the secondary phases in the film were not detected from X-ray diffraction, transmission electron microscopy, and zero-field cooling and field cooling. Apparently, the magnetic natures of powders and films come from different origins.

  14. Melting and casting of FeAl-based cast alloy

    SciTech Connect

    Sikka, V.K.; Wilkening, D.; Liebetrau, J.; Mackey, B.

    1998-11-01

    The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{trademark} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast.

  15. Yield stress anomaly in B2 FeAl

    SciTech Connect

    Yoshimi, K.; Hanada, S.; Yoo, M.H.

    1996-12-31

    The studies on yield stress anomaly of B2 FeAl single crystals are reviewed in this paper. A positive temperature dependence of yield stress, so-called yield stress anomaly, is observed in B2 FeAl in which excess vacancies are fully annealed out. Associated with the anomaly, characteristic asymmetry is found between tension and compression. While the strain-rate sensitivity is almost zero in the temperature range of the yield stress anomaly, the stress relaxation becomes significant with increasing temperature, indicating that a recovery process is thermally activated. It is ascertained by the two-surface trace analysis that slip transition from <111> direction at intermediate temperature to <100> at high temperature occurs around the peak temperature. Even at the peak temperature, in addition, operative slip vector for yielding is confirmed to be predominantly <111> by TEM. Also, it is observed that <111>-type superdislocations are frequently climb-dissociated in the temperature range of the anomaly. APB formation on {l_brace}111{r_brace} plane is energetically favorable, which is in agreement with the Flinn`s calculation for the B2 superlattice that APB energy on {l_brace}111{r_brace} plane is lower than that on {l_brace}110{r_brace} plane. Such an anisotropy of APB energy would offer specific driving force for the climb dissociation on <111> superdislocations. On the basis of the observed results, the anomalous strengthening behavior of B2 FeAl single crystals is discussed.

  16. Structural and optical properties of ZnO and ZnO:Fe nanoparticles under dense electronic excitations

    SciTech Connect

    Kumar, Shiv; Singh, Ranjan Kr.; Ghosh, Anup K.; Asokan, K.; Kanjilal, D.; Chatterjee, S.

    2013-10-28

    We report on the changes in structural, morphological, and optical properties of sol-gel derived ZnO and ZnO:Fe nanoparticles due to dense electronic excitations produced by heavy ion irradiations using 200 MeV Ag{sup +15} ion beams. X-ray diffraction studies with Rietveld refinement show that the samples are single phase and tensile strain has been developed in the ion-irradiated samples. The Raman spectroscopy measurements show that ion-irradiation results in microscopic structural disorders and breaking of translational symmetry giving rise to local distortions in the lattice. Atomic force microscopy studies show that roughness of the pellets increases strongly for pure ZnO as compared with Fe-doped ZnO due to ion-irradiation. Fourier transform infrared analysis confirms tetrahedral coordination of O ions surrounding the Zn-ions and surface modification of the nanoparticles. The UV-Vis spectroscopy measurements show that the band gap increases on Fe doping which may be due to 4s–3d and 2p–3d interactions and the Burstein-Moss band filling effect. The band gap decreases after irradiation which can be interpreted on the basis of creation of some new localized energy states above the valence band. Photoluminescence (PL) intensity is enhanced and two new emission bands viz. a blue band at ∼480 nm (related to surface defects) and a green band at ∼525 nm (related to O vacancies) are observed in ion-irradiated nanoparticles. The enhancement of PL-intensity in irradiated samples is attributed to the increase of different defect states and Zn−O bonds on the surfaces of the irradiated nanoparticles arising from surface modification.

  17. Molecular controls on Cu and Zn isotopic fractionation in Fe-Mn crusts

    NASA Astrophysics Data System (ADS)

    Little, S. H.; Sherman, D. M.; Vance, D.; Hein, J. R.

    2014-06-01

    The isotopic systems of the transition metals are increasingly being developed as oceanic tracers, due to their tendency to be fractionated by biological and/or redox-related processes. However, for many of these promising isotope systems the molecular level controls on their isotopic fractionations are only just beginning to be explored. Here we investigate the relative roles of abiotic and biotic fractionation processes in controlling modern seawater Cu and Zn isotopic compositions. Scavenging to Fe-Mn oxides represents the principal output for Cu and Zn to sediments deposited under normal marine (oxic) conditions. Using Fe-Mn crusts as an analogue for these dispersed phases, we investigate the phase association and crystal chemistry of Cu and Zn in such sediments. We present the results of an EXAFS study that demonstrate unequivocally that Cu and Zn are predominantly associated with the birnessite (δ-MnO2) phase in Fe-Mn crusts, as previously predicted from sequential leaching experiments (e.g., Koschinsky and Hein, 2003). The crystal chemistry of Cu and Zn in the crusts implies a reduction in coordination number in the sorbed phase relative to the free metal ion in seawater. Thus, theory would predict equilibrium fractionations that enrich the heavy isotope in the sorbed phase (e.g., Schauble, 2004). In natural samples, Fe-Mn crusts and nodules are indeed isotopically heavy in Zn isotopes (at ∼1‰) compared to deep seawater (at ∼0.5‰), consistent with the predicted direction of equilibrium isotopic fractionation based on our observations of the coordination environment of sorbed Zn. Further, ∼50% of inorganic Zn‧ is chloro-complexed (the other ∼50% is present as the free Zn2+ ion), and complexation by Cl- is also predicted to favour equilibrium partitioning of light Zn isotopes into the dissolved phase. The heavy Zn isotopic composition of Fe-Mn crusts and nodules relative to seawater can therefore be explained by an inorganic fractionation during

  18. ZnFe2O4-TiO2 Nanoparticles within Mesoporous MCM-41

    PubMed Central

    Tang, Aidong; Deng, Yuehua; Jin, Jiao; Yang, Huaming

    2012-01-01

    A novel nanocomposite ZnFe2O4-TiO2/MCM-41 (ZTM) was synthesized by a sol-gel method and characterized through X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), N2 adsorption-desorption, Raman spectroscopy, and ultraviolet visible (UV-vis) spectrophotometry. The results confirmed the incorporation of ZnFe2O4-TiO2 nanoparticles inside the pores of the mesoporous MCM-41 host without destroying its integrity. ZnFe2O4 nanoparticles can inhibit the transformation of anatase into rutile phase of TiO2. Incorporation of ZnFe2O4-TiO2 within MCM-41 avoided the agglomeration of nanoparticles and reduced the band gap energy of TiO2 to enhance its visible light photocatalytic activity. UV-vis absorption edges of ZTM nanocomposites redshifted with the increase of Zn/Ti molar ratio. The nanocomposite approach could be a potential choice for enhancing the photoactivity of TiO2, indicating an interesting application in the photodegradation and photoelectric fields. PMID:22919325

  19. Optical characterization of Sol-Gel ZnO:Al thin films

    NASA Astrophysics Data System (ADS)

    Ivanova, T.; Harizanova, A.; Koutzarova, T.; Vertruyen, B.

    2016-03-01

    This paper presents a sol-gel technological process for preparing thin films of ZnO and ZnO:Al. The effect of annealing treatments (500, 600, 700 and 800 °C) on their properties was studied. The structural evolution with the temperature was investigated by using X-Ray diffraction (XRD). Fourier Transform Infrared (FTIR) and UV-VIS spectrophotometry were applied to characterizing the films' vibrational and optical properties. The ZnO and ZnO:Al films possessed a polycrystalline structure. The films studied are highly transparent in the visible spectral range. The optical band gap values and the haze parameter were also determined.

  20. Study of difference in interfacial reaction at Fe{sub 3}O{sub 4}/ZnO and ZnO/Fe{sub 3}O{sub 4} heterostructure using synchrotron radiation

    SciTech Connect

    Wadikar, A. D. Master, Ridhi Choudhary, R. J. Phase, D. M.

    2014-04-24

    We have prepared Fe{sub 3}O{sub 4}/ZnO and ZnO/Fe{sub 3}O{sub 4} bilayer structure on p-Si substrate using pulsed laser deposition technique (PLD). X-ray diffraction study revealed (0001) oriented growth of ZnO and (111) oriented growth of Fe{sub 3}O{sub 4} in both the bilayer structure. We observed a change in the density of states near the Fermi level in valence band spectra in case of Fe{sub 3}O{sub 4}/ZnO bilayer when compared to that of ZnO/Fe{sub 3}O{sub 4}. Nonlinear current–voltage (I-V) characteristics were observed in both the samples confirmed that these bilayer structures can be used for spintronic application.

  1. Evolution of Fe Bearing Intermetallics During DC Casting and Homogenization of an Al-Mg-Si Al Alloy

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Grant, P. S.; O'Reilly, K. A. Q.

    2016-04-01

    The evolution of iron (Fe) bearing intermetallics (Fe-IMCs) during direct chill casting and homogenization of a grain-refined 6063 aluminum-magnesium-silicon (Al-Mg-Si) alloy has been studied. The as-cast and homogenized microstructure contained Fe-IMCs at the grain boundaries and within Al grains. The primary α-Al grain size, α-Al dendritic arm spacing, IMC particle size, and IMC three-dimensional (3D) inter-connectivity increased from the edge to the center of the as-cast billet; both α c-AlFeSi and β-AlFeSi Fe-IMCs were identified, and overall α c-AlFeSi was predominant. For the first time in industrial billets, the different Fe-rich IMCs have been characterized into types based on their 3D chemistry and morphology. Additionally, the role of β-AlFeSi in nucleating Mg2Si particles has been identified. After homogenization, α c-AlFeSi predominated across the entire billet cross section, with marked changes in the 3D morphology and strong reductions in inter-connectivity, both supporting a recovery in alloy ductility.

  2. Evolution of Fe Bearing Intermetallics During DC Casting and Homogenization of an Al-Mg-Si Al Alloy

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Grant, P. S.; O'Reilly, K. A. Q.

    2016-06-01

    The evolution of iron (Fe) bearing intermetallics (Fe-IMCs) during direct chill casting and homogenization of a grain-refined 6063 aluminum-magnesium-silicon (Al-Mg-Si) alloy has been studied. The as-cast and homogenized microstructure contained Fe-IMCs at the grain boundaries and within Al grains. The primary α-Al grain size, α-Al dendritic arm spacing, IMC particle size, and IMC three-dimensional (3D) inter-connectivity increased from the edge to the center of the as-cast billet; both α c-AlFeSi and β-AlFeSi Fe-IMCs were identified, and overall α c-AlFeSi was predominant. For the first time in industrial billets, the different Fe-rich IMCs have been characterized into types based on their 3D chemistry and morphology. Additionally, the role of β-AlFeSi in nucleating Mg2Si particles has been identified. After homogenization, α c-AlFeSi predominated across the entire billet cross section, with marked changes in the 3D morphology and strong reductions in inter-connectivity, both supporting a recovery in alloy ductility.

  3. Ni, Fe Co-doped ZnO nanoparticles synthesized by solution combustion method

    SciTech Connect

    Dhiman, Pooja Chand, Jagdish Verma, S. Sarveena, Singh, M.

    2014-04-24

    This paper outlines the synthesis and characterization of Ni-Fe co-doped ZnO nanoparticles by facile solution combustion method. The structural characterization by XRD confirmed the phase purity of the samples. Surface morphology studied by scanning electron microscope revealed cubic type shape of grains. EDS analysis conformed the elemental composition. Higher value of DC electrical conductivity and less band gap for co-doped ZnO from UV-Vis studies confirmed the change in defect chemistry of ZnO Matrix.

  4. Microwave absorption behavior of ZnO whisker modified by nanosized Fe3O4 particles.

    PubMed

    Hu, Shuchun; Wu, Guofeng; Huang, Zhenhao; Chen, Xiaolang

    2010-11-01

    Tetra-needle-like ZnO whisker was magnetic modified through in situ synthesis of nanosized Fe3O4 particles on the surface of the whisker, and the microwave absorption behavior of the as-prepared product was investigated in detail. The result of the comparative microwave absorbing experiment showed that the magnetic modified ZnO whisker appeared more superior property of microwave absorption than that of the original ZnO whisker in 2-18 GHz. Further investigation indicated that the microwave absorption behavior of the product was influenced by ferrite content and Fe3O4 particles' distribution in the product. When the ferrite content of the product changed from 2 wt% to 9 wt%, the microwave absorbing ability of the product was increased; then, the microwave absorbing ability of the product decreased with the further increasing of ferrite content from 9 wt% to 16 wt%. The product with uniform distribution of Fe3O4 particles showed better microwave absorption property than that with irregular distribution of Fe3O4 particles, and this result inferred that the biphase interface between ZnO and Fe3O4 contributed to microwave absorption through interface polarization. PMID:21137989

  5. Bioavailability of Fe and Zn in selected legumes, cereals, meat and milk products consumed in Fiji.

    PubMed

    Singh, Poonam; Prasad, Surendra; Aalbersberg, William

    2016-09-15

    The present study reports contents and the bioavailability of Fe and Zn from 25 selected raw and cooked food samples. The results showed highest variation of Fe content in raw food samples ranging from 2.19 ± 0.04 to 0.93 ± 0.03 mg/100g in legumes. The raw black eye bean, cheese and fish showed high Zn content up to 8.85 ± 0.01, 12.93 ± 0.26 and 172.03 ± 5.09 mg/100g, respectively. Pulses and cereals showed high level of ionizable Fe. Zn bioavailability was quite low in cereals as compared to pulses; 4.02% in yellow split to 17.40% in Bengal gram. Zn bioavailability of 17.40% is in cheese. Fe bioavailability is high in cooked rice 160.60%, white bread 428.30% and milk powder 241.67% showing that Fe bioavailability increased after cooking whereas the lowest in fish 0.84%. The multivariate and cluster analysis categorized studied foods into two main groups. PMID:27080888

  6. Influence of Fe-Doping on the Structural, Morphological, Optical, Magnetic and Antibacterial Effect of ZnO Nanostructures.

    PubMed

    Basith, N Mohamed; Vijaya, J Judith; Kennedy, L John; Bououdina, M; Shenbhagaraman, R; Jayavel, R

    2016-02-01

    Pure and Fe-doped ZnO nanostructures with different weight ratios (0.5, 1.0, 1.5, and 2.0 at wt% of Fe) were successfully synthesized by a facile microwave combustion method using urea as a fuel. The detailed structural characterization was performed by means of X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy and vibrating sample magnetometry (VSM). XRD patterns refined by the Rietveld method indicated that Fe-doped ZnO have a single pure phase with wurtzite structure, suggesting that Fe ions are successfully incorporated into ZnO crystal lattice by occupying Zn ionic sites. Interestingly, the morphology was found to change substantially from grains to nanoflakes and then into nanorods with the variation of Fe-content. The optical band gap estimated using DRS was found to be red-shifted from 3.220 eV for the pure ZnO nanostructures, then decreases up to 3.200 eV with increasing Fe-content. Magnetic studies showed that Fe-doped ZnO nanostructures exhibit room temperature ferromagnetism (RTFM) and the saturation magnetization attained a maximum value of 8.154 x 10(-3) emu/g for the highest Fe-content. The antibacterial activity of pure and Fe-doped ZnO nanostructures against a Gram-positive bacteria and Gram-negative bacteria was investigated. Pure ZnO and Fe-doped ZnO exhibited antibacterial activity, but it was considerably more effective in the 1.5 wt% Fe-doped ZnO nanostructures. PMID:27433623

  7. FeAl and NbAl3 Intermetallic-HVOF Coatings: Structure and Properties

    NASA Astrophysics Data System (ADS)

    Guilemany, J. M.; Cinca, N.; Dosta, S.; Cano, I. G.

    2009-12-01

    Transition metal aluminides in their coating form are currently being explored in terms of resistance to oxidation and mechanical behavior. This interest in transition metal aluminides is mainly due to the fact that their high Al content makes them attractive for high-temperature applications. This is also a reason to study their resistance to wear; they may be suitable for use in applications that produce a lot of wear in aggressive environments, thus replacing established coating materials. In this study, the microstructure, microhardness, and wear and oxidation performance of FeAl and NbAl3 coatings produced by high-velocity oxy-fuel spraying are evaluated with two main aims: (i) to compare these two coating systems—a commonly studied aluminide (FeAl) and, NbAl3, an aluminide whose deposition by thermal spraying has not been attempted to date—and (ii) to analyze the relationship between their microstructure, composition and properties, and so clarify their wear and oxidation mechanisms. In the present study, the higher hardness of niobium aluminide coatings did not correlate with a higher wear resistance and, finally, although pesting phenomena (disintegration in oxidizing environments) were already known of in bulk niobium aluminides, here their behavior in the coating form is examined. It was shown that such accelerated oxidation was inevitable with respect to the better resistance of FeAl, but further improvements are foreseen by addition of alloying elements in that alloy.

  8. Optical characterization of sol-gel ZnO:Al thin films

    NASA Astrophysics Data System (ADS)

    Ivanova, T.; Harizanova, A.; Koutzarova, T.; Vertruyen, B.

    2015-09-01

    This work presents a sol-gel approach for ZnO:Al films deposition. The effect of Al component and annealing treatments (from 500 to 800 °C) on the film structural and optical properties has been studied. Sol-gel ZnO and Al2O3 films are used for comparative analyses. Structural evolution as a function of annealing temperatures is investigated by using X-ray diffraction (XRD). XRD analysis of ZnO:Al films revealed that the predominant crystal phase is a wurtzite ZnO. It can be seen that the addition of Al leads to decaying of the film crystallinity. Fourier Transform Infrared (FTIR) and UV-VIS spectrophotometry are applied for characterization of the vibrational and optical properties. The Al component influences the shapes of the absorption bands. The optical properties of the sol-gel ZnO, ZnO:Al and Al2O3 films reveal very interesting features. Increasing Al component results in significantly higher film transparency.

  9. Mechanical Properties and Electrochemical Corrosion Behavior of Al/Sn-9Zn- xAg/Cu Joints

    NASA Astrophysics Data System (ADS)

    Huang, M. L.; Huang, Y. Z.; Ma, H. T.; Zhao, J.

    2011-03-01

    The effect of Ag content on the wetting behavior of Sn-9Zn- xAg on aluminum and copper substrates during soldering, as well as the mechanical properties and electrochemical corrosion behavior of Al/Sn-9Zn- xAg/Cu solder joints, were investigated in the present work. Tiny Zn and coarsened dendritic AgZn3 regions were distributed in the Sn matrix in the bulk Sn-9Zn- xAg solders, and the amount of Zn decreased while that of AgZn3 increased with increasing Ag content. The wettability of Sn-9Zn-1.5Ag solder on Cu substrate was better than those of the other Sn-9Zn- xAg solders but worse than that of Sn-9Zn solder. The wettability of Sn-9Zn-1.5Ag on the Al substrate was also better than those of the other Sn-9Zn- xAg solders, and even better than that of Sn-9Zn solder. The Al/Sn-9Zn/Cu joint had the highest shear strength, and the shear strength of the Al/Sn-9Zn- xAg/Cu ( x = 0 wt.% to 3 wt.%) joints gradually decreased with increasing Ag content. The corrosion resistance of the Sn-9Zn- xAg solders in Al/Sn-9Zn- xAg/Cu joints in 5% NaCl solution was improved compared with that of Sn-9Zn. The corrosion potential of Sn-9Zn- xAg solders continuously increased with increasing Ag content from 0 wt.% to 2 wt.% but then decreased for Sn-9Zn-3Ag. The addition of Ag resulted in the formation of the AgZn3 phase and in a reduction of the amount of the eutectic Zn phase in the solder matrix; therefore, the corrosion resistance of the Al/Sn-9Zn- xAg/Cu joints was improved.

  10. Al:ZnO thin film: An efficient matrix for cholesterol detection

    NASA Astrophysics Data System (ADS)

    Batra, Neha; Tomar, Monika; Gupta, Vinay

    2012-12-01

    Al doped ZnO thin film (Al:ZnO) has been realized as a potential matrix for the development of efficient cholesterol biosensor. The correlation between the structural and electrical properties of ZnO thin film with varying Al doping concentration (1% to 5%) and their cyclic voltammetric (CV) response has been studied. 2% Al doped ZnO films were found to give the best CV response and were further utilized for immobilization of cholesterol oxidase (ChOx) to detect cholesterol. Amperometric and photometric studies reveal that the prepared bioelectrode based on 2% Al doped ZnO matrix (ChOx/Al:ZnO/Pt/glass) is highly sensitive (sensitivity = 173 μAmM-1 cm-2) to the detection of cholesterol in the wide range from 0.6-12.9 mM (25-500 mg/dl). A relatively low value of enzyme's kinetic parameter (Michaelis menten constant, 2.53 mM) indicates enhanced affinity of the immobilized ChOx toward cholesterol. The prepared bioelectrode is found to be exhibiting high shelf life (10 weeks) having negligible interference with the presence of other biomolecules in human serum indicating promising application of Al doped ZnO thin films for cholesterol biosensing.

  11. Designing optical metamaterial with hyperbolic dispersion based on Al:ZnO/ZnO nano-layered structure using Atomic Layer Deposition technique

    DOE PAGESBeta

    Kelly, Priscilla; Liu, Mingzhao; Kuznetsova, Lyuba

    2016-04-07

    In this study, nano-layered Al:ZnO/ZnO hyperbolic dispersion metamaterial with a large number of layers was fabricated using the atomic layer deposition (ALD) technique. Experimental dielectric functions for Al:ZnO/ZnO structures are obtained by an ellipsometry technique in the visible and near-infrared spectral ranges. The theoretical modeling of the Al:ZnO/ZnO dielectric permittivity is done using effective medium approximation. A method for analysis of spectroscopic ellipsometry data is demonstrated to extract the optical permittivity for this highly anisotropic nano-layered metamaterial. The results of the ellipsometry analysis show that Al:ZnO/ZnO structures with a 1:9 ALD cycle ratio exhibit hyperbolic dispersion transition change near 1.8more » μm wavelength.« less

  12. Designing optical metamaterial with hyperbolic dispersion based on an Al:ZnO/ZnO nano-layered structure using the atomic layer deposition technique.

    PubMed

    Kelly, Priscilla; Liu, Mingzhao; Kuznetsova, Lyuba

    2016-04-10

    Nano-layered Al:ZnO/ZnO hyperbolic dispersion metamaterial with a large number of layers was fabricated using the atomic layer deposition (ALD) technique. Experimental dielectric functions for Al:ZnO/ZnO structures are obtained by an ellipsometry technique in the visible and near-infrared spectral ranges. The theoretical modeling of the Al:ZnO/ZnO dielectric permittivity is done using effective medium approximation. A method for analysis of spectroscopic ellipsometry data is demonstrated to extract the optical permittivity for this highly anisotropic nano-layered metamaterial. The results of the ellipsometry analysis show that Al:ZnO/ZnO structures with a 1:9 ALD cycle ratio exhibit hyperbolic dispersion transition change near 1.8 μm wavelength. PMID:27139865

  13. Tunable electric properties of half-metallic Zn x Fe3-x O4 and the characteristics of Zn x Fe3-x O4 /n-type Si interfaces

    NASA Astrophysics Data System (ADS)

    He, Jie; Wang, Changhong; Cheng, Yahui; Liu, Mengyin; Wang, Weichao; Wang, Weihua; Lu, Feng; Gao, Kuanghong; Li, Zhiqing; Liu, Hui

    2016-03-01

    The physical properties of Zn-doped Fe3O4 (i.e. Zn x Fe3-x O4 with 0≤slant x≤slant 1 ) synthesised by the sol-gel method have been investigated systematically. X-ray diffraction and x-ray photoelectron spectroscopy (XPS) measurements prove that Zn ions have been doped into the Fe3O4 crystal lattice. The valence band XPS spectra show that the carrier concentration decreases with increasing the Zn content. The electric measurements reveal that the resistivity increases when increasing the Zn concentration. The absolute value of the magnetoresistance of Zn x Fe3-x O4 is above 3.11% at room temperature, indicating that the samples maintain high spin polarisation after Zn2+ doping. The fitting of the current-voltage curves of Zn x Fe3-x O4/n-type Si heterostructures demonstrates that the height of the Schottky barrier reduces continuously from 0.82 eV to 0.76 eV with increasing x. The results may recommend Zn x Fe3-x O4 as a potential material for spintronic applications.

  14. Elevated Temperature Deformation of Fe-39.8Al and Fe-15.6Mn-39.4Al

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. Daniel

    2004-01-01

    The elevated temperature compressive properties of binary Fe-39.8 at % Al and Fe-15.6Mn-39.4Al have been measured between 1000 and 1300 K at strain rates between 10(exp 7) and 10(exp 3)/ s. Although the Mn addition to iron aluminide did not change the basic deformation characteristics, the Mn-modified alloy was slightly weaker. In the regime where deformation of FeAl occurs by a high stress exponent mechanism (n = 6), strength increases as the grain size decreases at least for diameters between approx. 200 and approx. 10 microns. Due to the limitation in the grain size-flow stress-temperature-strain rate database, the influence of further reductions of the grain size on strength is uncertain. Based on the appearance of subgrains in deformed iron aluminide, the comparison of grain diameters to expected subgrain sizes, and the grain size exponent and stress exponent calculated from deformation experiments, it is believed that grain size strengthening is the result of an artificial limitation on subgrain size as proposed by Sherby, Klundt and Miller.

  15. Mixing and non-stoichiometry in Fe-Ni-Cr-Zn-O spinel compounds: density functional theory calculations.

    PubMed

    Andersson, David A; Stanek, Christopher R

    2013-10-01

    Density functional theory (DFT) calculations have been performed on A(2+)B2(3+)O4(2-) (where A(2+) = Fe, Ni or Zn, and B(3+) = Fe or Cr) spinel oxides in order to determine some of their thermodynamic properties. Mixing energies were calculated for Fe3O4-NiFe2O4, Fe3O4-ZnFe2O4, Fe3O4-FeCr2O4, NiFe2O4-ZnFe2O4, NiFe2O4-NiCr2O4, FeCr2O4-NiCr2O4, FeCr2O4-ZnCr2O4 and ZnCr2O4-ZnFe2O4 pseudo-binaries based on special quasi random (SQS) structures to account for cationic disorder. The results generally agree with available experimental data and the rule that two normal or two inverse spinel compounds easily form solid solutions, while inverse-normal spinel mixtures exhibit positive deviation from solid solution behavior (i.e. immiscibility). Even though the NiFe2O4-NiCr2O4 and Fe3O4-FeCr2O4 systems obey this rule, they exhibit additional features with implications for the corresponding phase diagrams. In addition to mixing enthalpies, non-stoichiometry was also considered by calculating the energies of the relevant defect reactions resulting in A, B and O excess (or deficiency). The DFT calculations predict close to zero or slightly exothermic reactions for both A and B excess in a number of spinel compounds. PMID:23942481

  16. A novel approach to facilely synthesize mesoporous ZnFe2O4 nanorods for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Zhong, Xiao-Bin; Yang, Zhi-Zheng; Wang, Hui-Yuan; Lu, Lun; Jin, Bo; Zha, Min; Jiang, Qi-Chuan

    2016-02-01

    Despite the fact that ZnFe2O4 has various advantages as promising anode materials for lithium ion batteries (LIBs), ZnFe2O4 chronically suffers from limited cycle life, originating from poor electronic conductivity and huge volume changes. In this study, we address these traditional issues of ZnFe2O4 by fabricating a mesoporous nanorod structure through a novel, facile and scalable co-precipitation approach followed by thermal decomposition. The unique nanostructure not only effectively shortens the pathway for Li+ diffusion, but also provides a high porosity to effectively tolerate volume variation during charge/discharge processes. The reversible capacity of ZnFe2O4 can still reach 983 mAh g-1 at a specific current of 100 mA g-1 after 50 cycles. Mesoporous ZnFe2O4 nanorod could be demonstrated as a promising anode material for lithium-ion batteries.

  17. First principles investigation of Fe and Al bearing phase H

    NASA Astrophysics Data System (ADS)

    Tsuchiya, J.; Tsuchiya, T.

    2015-12-01

    The global circulation of water in the earth is important to investigate the evolution history and dynamics of the earth, since the physical properties (e.g. atomic diffusivity, melting temperature, electrical conductivity and seismic velocities) of the constituent minerals are considerably changed by the presence of water. It has been believed that water is carried into the deep Earth's interior by hydrous minerals such as the dense hydrous magnesium silicates (DHMSs) which are also known as alphabet phases (phase A, superhydrous phase B, and phase D etc.) in the descending cold plate. It has been thought that the relay of these hydrous phases was terminated at ~1200 km depth by the dehydration of phase D which was the highest pressure phase of DHMSs. Recently, we have theoretically predicted the high pressure phase of phase D and experimentally confirmed the existence of this new DHMS in lower mantle pressure conditions above ~45 GPa. This phase has MgSiO4H2chemical composition and named as phase H. At the lower mantle pressure conditions, Al and H-bearing SiO2, δ-AlOOH, ɛ-FeOOH and phase H may be the relevant hydrous phases in the subducting slabs. Interestingly, the crystal structure of these hydrous phases are almost same and have CaCl2type structure. This suggests that these hydrous phases may potentially be able to make the wide range of solid solution. Some experimental studies already reported that Al preferentially partitioned into phase H and the stability of phase H drastically increased by incorporation of Al (Nishi et al. 2014, Ohira et al. 2014). The density of subducted MORB is reported to be denser than that of pyrolite in the lower mantle (e.g. Kawai et al. 2009). Therefore, there is a possibility that phase H containing Al and Fe in subducted MORB survive down to the bottom of lower mantle and the melting of phase H at the core mantle boundary may contribute to the cause of ultra-low velocity zones. In this study, we further extends our

  18. Al-Ca and Al-Fe metal-metal composite strength, conductivity, and microstructure relationships

    SciTech Connect

    Kim, Hyong June

    2011-01-01

    Deformation processed metal-metal composites (DMMC’s) are composites formed by mechanical working (i.e., rolling, swaging, or wire drawing) of two-phase, ductile metal mixtures. Since both the matrix and reinforcing phase are ductile metals, the composites can be heavily deformed to reduce the thickness and spacing of the two phases. Recent studies have shown that heavily drawn DMMCs can achieve anomalously high strength and outstanding combinations of strength and conductivity. In this study, Al-Fe wire composite with 0.07, 0.1, and 0.2 volume fractions of Fe filaments and Al-Ca wire composite with 0.03, 0.06, and 0.09 volume fractions of Ca filaments were produced in situ, and their mechanical properties were measured as a function of deformation true strain. The Al-Fe composites displayed limited deformation of the Fe phase even at high true strains, resulting in little strengthening effect in those composites. Al-9vol%Ca wire was deformed to a deformation true strain of 13.76. The resulting Ca second-phase filaments were deformed to thicknesses on the order of one micrometer. The ultimate tensile strength increased exponentially with increasing deformation true strain, reaching a value of 197 MPa at a true strain of 13.76. This value is 2.5 times higher than the value predicted by the rule of mixtures. A quantitative relationship between UTS and deformation true strain was determined. X-ray diffraction data on transformation of Al + Ca microstructures to Al + various Al-Ca intermetallic compounds were obtained at the Advanced Photon Source at Argonne National Laboratory. Electrical conductivity was measured over a range of true strains and post-deformation heat treatment schedules.

  19. Identification of an incommensurate FeAl{sub 2} overlayer on FeAl(110) using x-ray diffraction and reflectivity

    SciTech Connect

    Baddorf, A.P.; Chandavarkar, S.S.

    1995-06-30

    FeAl, like NiAl, crystallizes in the CsCl structure. Consequently the (110) planes contain equal amounts of Fe and Al distributed as interlocking rectangles. Unlike the NiAI(110) surface, which retains the (1{times}l) in-plane symmetry of the bulk, FeAl(l10) reconstructs to form an ordered, incommensurate overlayer. The reconstructed layer introduces x-ray diffraction rods at half-order positions along the [1{bar 1}0] direction, and displaced {plus_minus}0.2905 from integer positions along the [001] direction. Peak widths reveal excellent long range order. Specular reflectivity measurements above and below the Fe K{alpha} edge can be reproduced using a model containing a single reconstructed overlayer with an Fe:Al ratio of 1:2, consistent with FeA{sub I}2.

  20. Thermally Diffused Al:ZnO Thin Films for Broadband Transparent Conductor.

    PubMed

    Tong, Chong; Yun, Juhyung; Chen, Yen-Jen; Ji, Dengxin; Gan, Qiaoqiang; Anderson, Wayne A

    2016-02-17

    Here, we report an approach to realize highly transparent low resistance Al-doped ZnO (AZO) films for broadband transparent conductors. Thin Al films are deposited on ZnO surfaces, followed by thermal diffusion processes, introducing the Al doping into ZnO thin films. By utilizing the interdiffusion of Al, Zn, and O, the chemical state of Al on the surfaces can be converted to a fully oxidized state, resulting in a low sheet resistance of 6.2 Ω/sq and an excellent transparency (i.e., 96.5% at 550 nm and higher than 85% up to 2500 nm), which is superior compared with some previously reported values for indium tin oxide, solution processed AZO, and many transparent conducting materials using novel nanostructures. Such AZO films are also applied as transparent conducting layers for AZO/Si heterojunction solar cells, demonstrating their applications in optoelectronic devices. PMID:26807664

  1. Fabrication and microstructural characterization of Al/Zn-enriched layers on pure magnesium

    SciTech Connect

    Mola, Renata

    2013-04-15

    Al/Zn-enriched surface layers were fabricated by heating Mg specimens in contact with Al–Zn powder mixtures in a vacuum furnace at 445 °C. The layer formation process took place through partial melting at the Mg-substrate/powder-mixture interface. Heating times ranged from 20 to 80 min. The layer microstructure and composition were analyzed by optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The layers were 100–900 μm in thickness, depending on the treatment time. The examination results revealed that the layers consisted of Mg{sub 17}(Al,Zn){sub 12} and Mg{sub 5}Al{sub 2}Zn{sub 2} intermetallic phases and a solid solution of Al and Zn in Mg. Between the Al/Zn-enriched layer and the Mg substrate, there was a transition zone of a solid solution of Al and Zn in Mg with a thickness of 20–30 μm. The layers had much higher microhardness than the Mg substrate. - Highlights: ► The layers were produced by heating Mg in contact with an Al–Zn powder mixture. ► The layer formation process at 445 °C proceeded with the liquid phase contribution. ► The Al/Zn-enriched layers were thick, dense, uniform and continuous. ► The layers contained Mg–Al–Zn intermetallic phases. ► The hardness of the layers was much higher than that of the Mg substrate.

  2. Lattice Changes in Shape Memory CuZnAl Alloys on Aging at Room Temperature

    NASA Astrophysics Data System (ADS)

    Çakmak, Seyfettýn; Artunç, Ekrem; Kayali, Nejdet; Adigüzel, Osman

    2001-09-01

    The aging behavior of CuZnAl martensites (Cu-21.62 wt.% Zn-5.68 wt.% Al and Cu-24.98 wt.% Zn-4.43 wt.% Al) at about 297 K was studied by analyzing diffraction line profiles obtained by X-ray diffractometry. For the alloys, the change of the lattice parameters and the tetragonality associated with the aging time at room temperature were investigated. The habit planes versus the aging time at room temperature were calculated using the De Vos-Aernoundt-Delaey model, based on the crystallographic theory of Wechsler-Lieberman-Read(WLR), and from the DO3→ 18R martensite transformation theory.

  3. Al and Zn Impurity Diffusion in Binary and Ternary Magnesium Solid-Solutions

    SciTech Connect

    Kammerer, Catherine; Kulkarni, Nagraj S; Warmack, Robert J Bruce; Sohn, Yong Ho

    2014-01-01

    Magnesium alloys are considered for implementation into structural components where energy-efficiency and light-weighting are important. Two of the most common alloying elements in magnesium alloys are Aluminum and Zinc. The present work examines impurity diffusion coefficients of Al and Zn in Mg(Zn) and Mg(Al) binary solid solutions, respectively. Experimental investigation is carried out with ternary diffusion couples with polycrystalline alloys. Concentration profiles were measured by electron microprobe micro-analysis and the impurity diffusion coefficients were determined by the Hall Method. Results of Al and Zn impurity diffusion in Mg solid solutions are reported, and examined as a function of composition of Mg solid solution.

  4. Effects of additions of small amounts of fourth elements on structure, crystal structure and shape recovery of Cu-Zn-Al shape memory alloys

    SciTech Connect

    Zhang, M.R. |; Yang, D.Z.; Tadaki, T.; Hirotsu, Y.

    1997-01-15

    Cu-based shape memory alloys (SMAs) are particularly interesting, compared to Ni-Ti SMAs because of their low cost and relatively ease process. However, there are important problems to be solved, such as intergranular fracture due to large grain size, stabilization of martensite, etc. In the present work, the influences of additions only less than 1 mass% of several fourth elements, such as Mn, Fe, Co, Ni, and Y, to two kinds of Cu-Zn-Al SMAs, i.e., Cu-30Zn-4Al and Cu-25Zn-7Al on their structure, crystal structure and shape recovery have been examined in order to know what elements are the most effective for the thermal stability of the parent and martensite phases and the shape memory capacity.

  5. Preparation and electromagnetic properties of Polyaniline(polypyrrole)-BaFe12O19/Ni0.8Zn0.2Fe2O4 ferrite nanocomposites

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Huang, Ying; Wang, Qiufen; He, Qian; Chen, Lin

    2012-10-01

    The nanocomposite of hard (BaFe12O19)/soft ferrite (Ni0.8Zn0.2 Fe2O4) was prepared by the sol-gel process, and then the polyaniline(PANI)/polypyrrole(PPY)-BaFe12O19/Ni0.8Zn0.2Fe2O4 was produced by in situ polymerization method. The structures, morphology and electromagnetic properties of the samples were characterized by various instruments. XRD, TEM, and FTIR analysis indicated that BaFe12O19/Ni0.8Zn0.2Fe2O4 ferrite were homogenously enwrapped by PANI(PPY) coating. The VSM and SDY-4 measurement show that the magnetic properties of the composites decreased with the increase in PANI(PPY) amount, However, the electrical conductivity is on the contrary. The electromagnetic properties of the composites were much better than BaFe12O19/Ni0.8Zn0.2Fe2O4 in the frequency range of 2-15 GHz, which mainly depends on the dielectric loss of PANI(PPY). A minimum reflection loss of the PANI(PPY)-BaFe12O19/Ni0.8Zn0.2Fe2O4 ferrite nanocomposite is -19.7 dB(-21.5 dB) at the frequency of 7.3 GHz (10.7 GHz).

  6. Modeling of the solubilities of NiO/NiAl2O4 and FeO/FeAl2O4 in cryolite melts at 1300 K

    NASA Astrophysics Data System (ADS)

    Zhang, Yunshu; Wu, Xiaoxia; Rapp, Robert A.

    2004-02-01

    Experiments to measure the solubilities of NiO/NiAl2O4 and FeO/FeAl2O4 were performed, and the results confirmed existing literature values. The solubilities of NiAl2O4 and FeAl2O4 in Al2O3-saturated cryolite melts at 1300 K were modeled thermodynamically in terms of the Ni-containing complexes Na2NiF4 and Na4NiF6, and the Fe-containing solutes FeF2, Na2FeF4, and Na4FeF6. The experimental solubility data were fitted to multiple simultaneous equilibria. Equilibrium constants and ΔG f 0 values for the formation reactions of the these solutes were thereby estimated. The solubilities of NiO/NiAl2O4 and FeO/FeAl2O4 and solute distributions in Al2O3-undersaturated cryolite melts were calculated for a number of melt compositions from the present model. The existence of several competitive solute species is inherent to highly buffered ionic cryolite solutions where the traditional log-log methodology had previously failed to identify dominant single solutes. In such solutions, individual solutes of oxides are not likely to dominate over a wide composition range so that a more global modeling is required. The principal solute species identified in the present study exhibit reasonable three-dimensional (3-D) anion geometries.

  7. Fabrication of Al-Doped ZnO Film with High Conductivity Induced by Photocatalytic Activity

    NASA Astrophysics Data System (ADS)

    Hong, Jeongsoo; Katsumata, Ken-ichi; Matsushita, Nobuhiro

    2016-06-01

    We have fabricated Al-doped ZnO films by a spin-spray method, achieving high conductivity by Al-ion doping and photocatalytic activity of the ZnO. The surface morphology of the as-deposited films was varied by changing the Al concentration and addition of citrate ions. As-deposited Al-doped ZnO film without citrate ions showed rod array structure with increasing rod width as the Al concentration was increased. Meanwhile, Al-doped ZnO film deposited with addition of citrate ions changed to exhibit dense and continuous surface morphology with high transmittance of 85%. The lowest resistivity recorded for undoped and Al-doped ZnO film was 2.1 × 10-2 Ω cm and 5.9 × 10-3 Ω cm, after ultraviolet (UV) irradiation. The reason for the decreased resistivity is thought to be that Al-ion doping and the photocatalytic activity of ZnO contributed to improve the conductivity.

  8. Erosion behavior of Fe-Al intermetallic alloys

    SciTech Connect

    Kim, Y.S.; Song, J.H.; Chang, Y.W.

    1997-04-01

    The Fe-rich Fe-Al intermetallics have generated some interest, especially during the last decade, due to their excellent resistance for oxidation and sulfidation, high specific strength, and low material cost. The aluminide is therefore considered as one of the promising candidates for high-temperature structural materials in a corrosive atmosphere. Research effort has been focused mainly on process, development, and enhancement of room-temperature ductility together with the characterization of physical properties such as mechanical properties, oxidation, corrosion, and abrasive wear behavior. However, there have been only a few works reported to date in regard to the erosion characteristics of the alloy, one of the most important material property of this ordered intermetallic alloy for the use in a fossil-fuel plant. In this study, the solid-particle erosion behavior of the Fe-Al intermetallic alloys containing the various aluminum contents ranging from 25 to 30 at.% has been investigated to clarify the effect of aluminum content and different ordered structures, viz. DO{sub 3} and B2, on the erosion behavior. An attempt has been made to correlate the erosion behavior of these intermetallics to their mechanical properties by carrying out tensile tests together with SEM observation of the eroded surfaces.

  9. Hydrogen permeation characteristics of some Fe-Cr-Al alloys

    NASA Astrophysics Data System (ADS)

    Van Deventer, E. H.; Maroni, V. A.

    1983-01-01

    Hydrogen permeation data are reported for two Fe-Cr-Al alloys, Type-405 SS (Cr 14-A1 0.2) and a member of the Fecralloy family of alloys (Cr 16-A1 5). The hydrogen permeability of each alloy (in a partially oxidized condition) was measured over a period of several weeks at randomly selected temperatures (between 150 and 850°C) and upstream H 2 pressures (between 2 and 1.5 × 10 4 Pa). The permeabilities showed considerable scatter with both time and temperature and were 10 2 to 10 3 times lower than those of pure iron, even in strongly reducing environments. The exponent, n, for the relationship between upstream H 2 pressure, P, and permeability, φ, ( φ ~ Pn) was closer to 0.7 than to the expected 0.5, indicating a process limited by surface effects (e.g., surface oxide films) as opposed to bulk material effects. Comparison of these results with prior permeation measurements on other Fe-Cr-Al alloys, on Fe-Cr alloys, and on pure iron shows that the presence of a few weight percent aluminum offers the best prospects for achieving low tritium permeabilities with martensitic and ferritic steels used in fusion-reactor first wall and blanket applications.

  10. Equilibrium point defects in intermetallics with the [ital B]2 structure: NiAl and FeAl

    SciTech Connect

    Fu, C.L.; Ye, Y.; Yoo, M.H. ); Ho, K.M. )

    1993-09-01

    Equilibrium point defects and their relation to the contrasting mechanical behavior of NiAl and FeAl are investigated. For NiAl, the defect structure is dominated by two types of defects---monovacancies on the Ni sites and substitutional antisite defects on the Al sites. The defect structure of FeAl differs from that of NiAl in the occurrence of antisite defects at the transition-metal sites for Al-rich alloys and the tendency for vacancy clustering. The strong ordering (and brittleness) of NiAl is attributed mainly to the difference in atomic size between constituent atoms.

  11. Zinclipscombite, ZnFe{2/3+}(PO4)2(OH)2, a new mineral species

    NASA Astrophysics Data System (ADS)

    Chukanov, N. V.; Pekov, I. V.; Möckel, S.; Zadov, A. E.; Dubinchuk, V. T.

    2007-12-01

    Zinclipscombite, a new mineral species, has been found together with apophyllite, quartz, barite, jarosite, plumbojarosite, turquoise, and calcite at the Silver Coin mine, Edna Mountains, Valmy, Humboldt County, Nevada, United States. The new mineral forms spheroidal, fibrous segregations; the thickness of the fibers, which extend along the c axis, reaches 20 μm, and the diameter of spherulites is up to 2.5 mm. The color is dark green to brown with a light green to beige streak and a vitreous luster. The mineral is translucent. The Mohs hardness is 5. Zinclipscombite is brittle; cleavage is not observed; fracture is uneven. The density is 3.65(4) g/cm3 measured by hydrostatic weighing and 3.727 g/cm3 calculated from X-ray powder data. The frequencies of absorption bands in the infrared spectrum of zinclipscombite are (cm-1; the frequencies of the strongest bands are underlined; sh, shoulder; w, weak band) 3535, 3330sh, 3260, 1625w, 1530w, 1068, 1047, 1022, 970sh, 768w, 684w, 609, 502, and 460. The Mössbauer spectrum of zinclipscombite contains only a doublet corresponding to Fe3+ with sixfold coordination and a quadrupole splitting of 0.562 mm/s; Fe2+ is absent. The mineral is optically uniaxial and positive, ω = 1.755(5), ɛ = 1.795(5). Zinclipscombite is pleochroic, from bright green to blue-green on X and light greenish brown on Z ( X > Z). Chemical composition (electron microprobe, average of five point analyses, wt %): CaO 0.30, ZnO 15.90, Al2O3 4.77, Fe2O3 35.14, P2O5 33.86, As2O5 4.05, H2O (determined by the Penfield method) 4.94, total 98.96. The empirical formula calculated on the basis of (PO4,AsO4)2 is (Zn0.76Ca0.02)Σ0.78(Fe{1.72/3+} Al0.36)Σ2.08[(PO4)1.86(AsO4)0.14]Σ2.00(OH)1. 80 · 0.17H2O. The simplified formula is ZnFe{2/3+} (PO4)2(OH)2. Zinclipscombite is tetragonal, space group P43212 or P41212; a = 7.242(2) Å, c = 13.125(5) Å, V = 688.4(5) Å3, Z = 4. The strongest reflections in the X-ray powder diffraction pattern ( d, ( I, %) (( hkl

  12. ZnO:Al thin films deposited by RF-magnetron sputtering with tunable and uniform properties.

    PubMed

    Miorin, E; Montagner, F; Battiston, S; Fiameni, S; Fabrizio, M

    2011-03-01

    Nanostructured, high quality and large area Al-doped ZnO (ZnO:Al) thin films were obtained by radiofrequency (RF) magnetron sputtering. The sample rotation during deposition has resulted in excellent spatial distribution of thickness and electro-optical properties compared to that obtained under static conditions. ZnO:Al thin films are employed in a large number of devices, including thin film solar cells, where the uniformity of the properties is a key factor for a possible up-scaling of the research results to industrially relevant substrate sizes. A chemical post etching treatment was employed achieving tunable surface nanotextures to generate light scattering at the desired wavelength for improved cell efficiency. Since the film resistivity is only slightly increased by the etching, this post-deposition step allows separating the optimization of electro-optical properties from light scattering behavior. The thin films were characterized by FE-SEM, XRD, UV-VIS spectroscopy, four probe and van der Paw techniques. PMID:21449368

  13. Cryogenic and elevated temperature strengths of an Al-Zn-Mg-Cu alloy modified with Sc and Zr

    NASA Astrophysics Data System (ADS)

    Senkova, S. V.; Senkov, O. N.; Miracle, D. B.

    2006-12-01

    The effect of minor additions of Sc and Zr on tensile properties of two developmental Al-Zn-Mg-Cu alloys was studied in the temperature range -196°C to 300°C. Due to the presence of Sc and Zr in a fine dispersoid form, both low-temperature and elevated temperature strengths of these alloys are much higher than those of similar 7000 series alloys that do not contain these elements. After short holding times (up to 10 hours) at 205°C, the strength of these alloys is higher than those of high-temperature Al alloys 2219-T6 and 2618-T6; however, the latter alloys show better strength after longer holding times. It is suggested that additional alloying of the Sc-containing Al-Zn-Mg-Cu alloys with other dispersoid-forming elements, such as Ni, Fe, Mn, and Si, with a respective decrease in the amounts of Zn and Mg may further improve the elevated temperature strength and decrease the loss of strength with extended elevated temperature exposure.

  14. Effect of Cr and Al substitution cations on the structural and magnetic properties of Ni0.6Zn0.4Fe2-xCrx/2Alx/2O4 nanoparticles synthesized using the sol-gel auto-combustion method

    NASA Astrophysics Data System (ADS)

    Ghasemi, Ali; Ekhlasi, Sima; Mousavinia, Mohammad

    2014-03-01

    The Ni0.6Zn0.4Fe2-xCrx/2Alx/2O4 (x=0-0.5) nanoparticles were prepared by employing the sol-gel auto-combustion method. The effect of aluminum and chromium on the structural and superparamagnetic properties of prepared samples was investigated using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy, vibrating sample magnetometry (VSM), ac magnetic susceptibility and magnetization temperature curve recording in ZFC mode analysis. The XRD analysis of all synthesized samples confirmed the formation of single-phase cubic spinel structure. The results of FTIR analysis indicated that the functional groups of Ni-Zn spinel ferrite were formed during the auto-combustion sol-gel process. Moreover, FE-SEM and TEM micrographs demonstrated that nanoparticles with narrow size distribution were obtained. According to VSM results by increasing substitution contents, saturation magnetization decreased. Magnetic dynamics of the samples was studied by measuring ac magnetic susceptibility versus temperature at different frequencies. The phenomenological Néel-Brown and Vogel-Fulcher models were employed to distinguish between the interacting or noninteracting system. Results exhibited that there is a strong interaction between nanoparticles. A frequency-dependence peak was observed in ac magnetic susceptibility versus temperature for nanoparticles which is well fitted by the Vogel-Fulcher model. It is confirmed that there is strong magnetic interaction among prepared nanoparticles.

  15. Visible light photo-degradation of methylene blue over Fe or Cu promoted ZnO nanoparticles

    NASA Astrophysics Data System (ADS)

    Mardani, Hamid Reza; Forouzani, Mehdi; Ziari, Mitra; Biparva, Pourya

    2015-04-01

    CuxZn(1-x)O, FexZn(1-x)O (x = 0.01) and ZnO nanoparticles were and were characterized by X-ray diffraction, ultraviolet and visible spectroscopy, FTIR spectroscopy and SEM. The photodegradation of an aqueous solution of methylene blue (as an organic pollutant) by nanoparticles with H2O2 (30%) under visible light and the progress of the reaction were monitored by UV-Vis spectroscopy absorption. The photocatalytic oxidation efficiency of all nanoparticles was 100% at the appropriate time. The degradation time was 90 min for FeZnO, 120 min for CuZnO and 210 min for ZnO. This indicates that the photocatalytic activity of the doped nanoparticles was better than that of ZnO alone. ZnO doped with a small amount of Fe or Cu decreased the size of the nanoparticles and the band gap and increased photocatalytic efficiency.

  16. Enhanced photovoltaic performance of quantum dot-sensitized solar cell fabricated using Al-doped ZnO nanorod electrode

    NASA Astrophysics Data System (ADS)

    Raja, M.; Muthukumarasamy, N.; Velauthapillai, Dhayalan; Balasundrapraphu, R.; Senthil, T. S.; Agilan, S.

    2015-04-01

    ZnO and Al doped ZnO nanorods have been successfully synthesized on ITO substrate via solgel dip coating method without using any catalyst. The X-ray diffraction studies showed that the Al doped ZnO samples are of hexagonal wurtzite structure. The Al ions were successfully incorporated into the ZnO lattice. Scanning electron microscopy images reveal that the average diameter of ZnO nanorods and Al doped ZnO nanorods are ∼300 nm and ∼200 nm respectively. The energy dispersive X-ray (EDS) analysis confirmed the presence Al in the ZnO thin films. The CdS quantum dot sensitized Al doped ZnO solar cell exhibited a power conversion efficiency of 1.5%.

  17. Chemical mixing at “Al on Fe” and “Fe on Al” interfaces

    SciTech Connect

    Süle, P.; Horváth, Z. E.; Kaptás, D.; Bujdosó, L.; Balogh, J.; Nakanishi, A.

    2015-10-07

    The chemical mixing at the “Al on Fe” and “Fe on Al” interfaces was studied by molecular dynamics simulations of the layer growth and by {sup 57}Fe Mössbauer spectroscopy. The concentration distribution along the layer growth direction was calculated for different crystallographic orientations, and atomically sharp “Al on Fe” interfaces were found when Al grows over (001) and (110) oriented Fe layers. The Al/Fe(111) interface is also narrow as compared to the intermixing found at the “Fe on Al” interfaces for any orientation. Conversion electron Mössbauer measurements of trilayers—Al/{sup 57}Fe/Al and Al/{sup 57}Fe/Ag grown simultaneously over Si(111) substrate by vacuum evaporation—support the results of the molecular dynamics calculations.

  18. Genetic diversity and selection of genotypes to enhance Zn and Fe content in common bean

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Common bean (Phaseolus vulgaris L.) is an important source of dietary protein and minerals worldwide. Genes conditioning variability for mineral contents are not clearly understood. Our ultimate goal is to identify genes conditioning genetic variation for Zn and Fe content. To establish mapping popu...

  19. Mn, Fe, Zn and As speciation in a fast-growing ferromanganese marine nodule

    SciTech Connect

    Marcus, Matthew A.; Manceau, Alain; Kersten, Michael

    2004-04-01

    The speciation of Mn, Fe, As and Zn in a fast-growing (0.02mm/yr), shallow-marine ferromanganese nodule has been examined by micro X-ray fluorescence, micro X-ray diffraction, and micro X-ray absorption spectroscopy. This nodule exhibits alternating Fe-rich and Mn-rich layers reflecting redox variations in water chemistry. Fe occurs as two-line ferrihydrite. The As is strictly associated with Fe and is mostly pentavalent, with an environment similar to that of As sorbed on or coprecipitated with synthetic ferrihydrite. The Mn is in the form of turbostratic birnessite with {approx} 10 percent trivalent manganese in the layers and probably {approx} 8 percent corner-sharing metal octahedra in the interlayers. The Zn is enriched on the rim of the nodule, associated with Mn. The Zn is completely (>90 percent) tetrahedrally coordinated and sorbed in the interlayers of birnessite on vacant layer Mn sites. The Zn and Mn species are similar to ones found in soils, suggesting common structural principles, despite the differing formation conditions in these systems.

  20. Identification of putative target genes to manipulate Fe and Zn concentrations in rice grains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rice is the staple food of half of the world’s population; however, it is a poor source of essential micronutrients such as Fe and Zn. Since flag leaves are one of the sources of remobilized metals for developing seeds, the identification of the molecular players that might contribute to the process...

  1. Influence Al doped ZnO nanostructure on structural and optical properties

    NASA Astrophysics Data System (ADS)

    Ramelan, Ari Handono; Wahyuningsih, Sayekti; Chasanah, Uswatul; Munawaroh, Hanik

    2016-04-01

    The preparation of Al-doped ZnO (AZO) thin films prepared by the spin-coating method was reported. Preparation of AZO was conducted by annealing treatment at a temperature of 700°C. While the spin-coating process of AZO thin films were done at 2000 and 3000 rpm respectively. The structural properties of ZnO were determined by X- ray diffraction (XRD) analysis. ZnOnanostructure was formed after annealed at atemperature of 400°C.The morphology of ZnO was determined by Scanning Electron Microscopy (SEM) showed the irregular morphology about 30-50µm in size. Al doped on ZnO influenced the optical properties of those material. Increasing Al contain on ZnO cause of shifting to the lower wavelength. The optical properties of the ZnO as well as AZO films showed that higher reflectance on the ultraviolet region so those materials were used as anti-reflecting agent.Al addition significantly enhance the optical transparency and induce the blue-shift in optical bandgap of ZnO films.

  2. Fe3O4/CuO/ZnO/Nano graphene platelets (Fe3O4/CuO/ZnO/NGP) composites prepared by sol-gel method with enhanced sonocatalytic activity for the removal of dye

    NASA Astrophysics Data System (ADS)

    Hendry, Tju; Taufik, Ardiansyah; Saleh, Rosari

    2016-04-01

    In this study, an attempt has been made to synthesize nanographene platelets coupled with Fe3O4/CuO/ZnO (Fe3O4/CuO/ZnO/NGP) with various ZnO loadings using a two step methods, sol-gel followed by hydrothermal method. Characterization was carried out by X-ray diffraction, energy-dispersive X-ray spectroscopy and vibrating sample magnetometer. The sonocatalytic performance was evaluated by degradation of methylene blue under ultrasonic irradiation.The Fe3O4/CuO/ZnO/NGP showed superior sonocatalytic activity than the Fe3O4/CuO/ZnO materials. They also showed high stability and can be easily separated from the reaction system for recycling process.

  3. Electronic structure of Zn doped Fe3O4 thin films.

    PubMed

    Park, J W; Jang, A N; Song, J H; Park, C Y; Lee, Y S

    2013-03-01

    We investigated the effect of Zn doping on the electronic property of magnetite by using optical spectroscopy. The (Zn(x)Fe(1-x))Fe2O4 (ZFFO) (x = 0, 0.2, 0.4, and 0.5) samples were prepared by PLD technique. The XRD measurement revealed that all the samples have an inverse spinel-type of crystalline structure. The M-H curves indicate that the saturation magnetization reduces with the increasing x. From the spectroscopic ellipsometry and infrared spectroscopy, we found that the doping of nonmagnetic Zn2+ ions leads to the dramatic change in the electronic structure of the ZFFO films. We discuss the correlation of our spectra with the electric and magnetic properties of the ZFFO films. PMID:23755615

  4. Magnetic properties of ZnFe2O4 ferrite nanoparticles embedded in ZnO matrix

    NASA Astrophysics Data System (ADS)

    Guskos, N.; Glenis, S.; Zolnierkiewicz, G.; Typek, J.; Berczynski, P.; Guskos, A.; Sibera, D.; Narkiewicz, U.

    2012-03-01

    Two magnetic nanocomposites were prepared from nanocrystalline zinc oxide doped with different concentrations of iron oxide (5 and 10 wt. %). X-ray diffraction and scanning electron microscopy have shown the growth of ZnFe2O4 nanocrystallites with size below 10 nm within the ZnO matrix in a highly agglomerated structure. Ferromagnetic resonance (FMR) measurements have shown line arising from the ZnFe2O4 nanoparticles. Temperature dependence of the FMR spectra parameters (amplitude, resonance field, linewidth, integrated intensity) has been investigated in the 4-300 K range. Zero-field cooled and field-cooled dc magnetic magnetization study in the same temperature range allowed to determine the blocking temperature TB and compare the results of two applied magnetic methods. Temperature dependence of FMR integrated intensity curve displays a peak at TB ˜ 23 K while FMR amplitude curve peaks at TC ˜ 170 K, the Curie-Weiss temperature of the high temperature susceptibility.

  5. Optical properties of post-annealed ZnO:Al thin films studied by spectroscopic ellipsometry

    SciTech Connect

    Hwang, Y.H.; Kim, H.M.; Um, Y.H.; Park, H.Y.

    2012-10-15

    In this paper, effects of the thermal annealing on the structural, electrical, and optical properties of Al-doped ZnO (ZnO:Al) thin films prepared by reactive radio-frequency sputtering were investigated. From the X-ray diffraction observations, the orientation of ZnO:Al films was found to be a c-axis in the hexagonal structure. The optical properties of the films were investigated by optical transmittance and spectroscopic ellipsometry characterization. Based on Tauc–Lorentz model, the optical constants of ZnO:Al films were extracted in the photon energy ranging from 1.0 to 4.5 eV. Our result showed that the refractive index and extinction coefficient of the films changed consistently with annealing temperature.

  6. Magnetic properties of CoFe2O4 and ZnFe2O4 nanoparticles synthesized by novel chemical route

    NASA Astrophysics Data System (ADS)

    Kharat, S. P.; Darvade, T. C.; Gaikwad, S. K.; Baraskar, B. G.; Kakade, S. G.; Kambale, R. C.; Kolekar, Y. D.

    2016-05-01

    CoFe2O4 and ZnFe2O4 nanoparticles were synthesized by modified and cost effective sol-gel autocombustion method. X-ray diffraction study confirms the spinel phase formation of face centered cubic lattice with space group Fd3m and without any impurity. Magnetic measurements demonstrate that the CoFe2O4 shows saturation magnetization of 2.73 µB/f.u. where as ZnFe2O4 shows paramagnetic behavior. Magnetic behavior of CoFe2O4 and ZnFe2O4 is confirmed from Mössbauer studies. Effect of sintering on structural, magnetic and cation occupancy of substituted cobalt ferrite is discussed in this paper.

  7. In situ corrosion analysis of Al-Zn-In-Mg-Ti-Ce sacrificial anode alloy

    SciTech Connect

    Ma Jingling Wen Jiuba; Zhai Wenxia; Li Quanan

    2012-03-15

    The corrosion behaviour of Al-5Zn-0.02In-1Mg-0.05Ti-0.5Ce (wt.%) alloy has been investigated by immersion test, scanning electron microscopy, energy dispersive X-ray detector, electrochemical impedance spectroscopy and electrochemical noise. The results show that there exist different corrosion types of the alloy in 3.5% NaCl solution with the immersion time. At the initial stage of immersion, pitting due to the precipitates predominates the corrosion with a typical inductive loop at low frequencies in electrochemical impedance spectroscopy. The major precipitates of the alloy are MgZn{sub 2} and Al{sub 2}CeZn{sub 2} particles. The corrosion potentials of the bulk MgZn{sub 2} and Al{sub 2}CeZn{sub 2} alloys are negative with respect to that of {alpha}-Al, so the MgZn{sub 2} and Al{sub 2}CeZn{sub 2} precipitates can act as activation centre and cause the pitting. In the late corrosion, a relative uniform corrosion predominates the corrosion process controlled by the dissolution/precipitation of the In ions and characterized by a capacitive loop at medium-high frequencies in electrochemical impedance spectroscopy. The potential noise of the pitting shows larger amplitude fluctuation and lower frequency, but the potential noise of the uniform corrosion occurs with smaller amplitude fluctuation and higher frequency.

  8. A putative function for the arabidopsis Fe-Phytosiderophore transporter homolog AtYSL2 in Fe and Zn homeostasis.

    PubMed

    Schaaf, Gabriel; Schikora, Adam; Häberle, Jennifer; Vert, Grégory; Ludewig, Uwe; Briat, Jean-François; Curie, Catherine; von Wirén, Nicolaus

    2005-05-01

    Although Arabidopsis thaliana does not produce phytosiderophores (PS) under Fe deficiency, it contains eight homologs of the metal-PS/metal-nicotianamine (NA) transporter ZmYS1 from maize. This study aimed to investigate whether one of the closest Arabidopsis homologs to ZmYS1, AtYSL2, is involved in metal-chelate transport. Northern analysis revealed high expression levels of AtYSL2 in Fe-sufficient or Fe-resupplied roots, while under Fe deficiency transcript levels decreased. Quantitative real-time polymerase chain reaction (PCR) and analysis of transgenic plants expressing an AtYSL2 promoter::beta-glucuronidase gene further allowed the detection of down-regulated AtYSL2 gene expression under Zn and Fe deficiency. In contrast to ZmYS1, AtYSL2 did not mediate metal-PS or metal-NA transport in yeast mutants defective in Cu or Fe uptake, nor did AtYSL2 mediate Fe(II)-NA-, Fe(III)-NA- or Ni(II)-NA-inducible currents when assayed by two-electrode voltage clamp in Xenopus oocytes. Moreover, truncation of the N-terminus to remove putative phosphorylation sites that might trigger autoinhibition did not confer functionality to AtYSL2. A direct growth comparison of yeast cells transformed with AtYSL2 in two different yeast expression vectors showed that transformation with empty pFL61 repressed growth even under non-limiting Fe supply. We therefore conclude that the yeast complementation assay previously employed does not allow the identification of AtYSL2 as an Fe-NA transporter. Transgenic plants expressing an AtYSL2 promoter::beta-glucuronidase gene showed expression in root endodermis and pericycle cells facing the meta-xylem tubes. Taken together, our investigations support an involvement of AtYSL2 in Fe and Zn homeostasis, although functionality or substrate specificity are likely to differ between AtYSL2 and ZmYS1. PMID:15753101

  9. Magnetotransport Properties of Co2FeAl Nanowires

    NASA Astrophysics Data System (ADS)

    Sapkota, Keshab; Gyawali, P.; Dahal, Bishnu; Dulal, R.; Pegg, I. L.; Philip, John

    2013-03-01

    Co2FeAl (CFA) nanowire (NW) exhibit interesting magnetic behavior with temperature, which arises from the granular structure.[2] To understand the magnetotransport properties, single CFA NW devices were fabricated using standard electron beam lithography. The magnetoresistance measurements of single CFA NW device were carried out at different temperatures. The magnetoresistance measurements show oscillations as a function of applied external magnetic field. This work has been supported by funding from NSF under CAREER Grant No. ECCS-0845501 and NSF-MRI, DMR-0922997.

  10. MOKE Study of Fe/Co/Al Multilayers

    SciTech Connect

    Jani, Snehal; Lakshmi, N.; Venugopalan, K.; Rajput, Parasmani; Zajaoc, M.; Rueffer, R.; Reddy, V. R.; Gupta, Ajay

    2011-07-15

    The multilayer system (MLS)-[{sup 57}Fe{sub 25}A/Co{sub 11}A/Al{sub 17}A]x20 has been deposited by Ion beam sputtering (IBS) technique. The MLS has been annealed at 700 deg. C for 1 h. Overall composition of as deposited and annealed MLS have been characterized by EDX and magnetic properties have been studied through angular dependent magneto optic Kerr effect (MOKE) hysteresis curves. The study shows that the as-deposited MLS has excellent soft magnetic properties coupled with perpendicular magnetic isotropy which is destroyed on annealing.

  11. Zener Relaxation Peak in an Fe-Cr-Al Alloy

    NASA Astrophysics Data System (ADS)

    Zhou, Zheng-Cun; Cheng, He-Fa; Gong, Chen-Li; Wei, Jian-Ning; Han, Fu-Sheng

    2002-11-01

    We have studied the temperature spectra of internal friction and relative dynamic modulus of the Fe-(25 wt%)Cr-(5 wt%)Al alloy with different grain sizes. It is found that a peak appears in the internal friction versus temperature plot at about 550°C. The peak is of a stable relaxation and is reversible, which occurs not only during heating but also during cooling. Its activation energy is 2.5 (+/- 0.15) eV in terms of the Arrhenius relation. In addition, the peak is not obvious in specimens with a smaller grain size. It is suggested that the peak originates from Zener relaxation.

  12. Annealing of cold-rolled Fe-40Al single crystals

    SciTech Connect

    Yang, Y.; Baker, I.

    1997-12-31

    Single crystals of Fe-40Al were cold-rolled to plastic strains in the range 5% to 48%. Discs cut from the rolled crystals at different rolling strains were heated at 10 K/min in a differential scanning calorimeter from room temperature to 973 K. Three exothermic peaks were observed in the temperature ranges of 440--550 K, 610--650 K, and 860--930 K, all the peaks shifting to lower temperatures with increasing strain. The origins of these peaks are discussed in terms of the disorder and vacancies introduced during rolling.

  13. Mechanical and magnetic properties of ZnO/Fe2O3 ceramic varistors

    NASA Astrophysics Data System (ADS)

    Sedky, A.; Ziq, Kh. A.

    2012-07-01

    Mechanical and magnetic properties of the ZnO/Fe2O3 ceramic varistors have been examined by using mechanical analyzer, digital microhardness tester and vibrating sample magnetometer. The initial stress-strain behavior is found to be linear (elastic) then becomes nonlinear (plastic deformation) without reaching the failure limit up to the maximum available stress (0.07 MPa). The compressive elastic modulus varies between 0.2 and 0.8 MPa with Fe addition up to 0.50. Furthermore, an approximately monotonically linear decrease in VHN with increasing Fe content up to 50% has been observed for all applied loads, which closely resembles the behavior of the true hardness and the surface energy. The magnetic measurements revealed an antiferromagnetic to paramagnetic to transition for all Fe doped samples. The Fe free sample showed paramagnetic behavior down to 2 K. The Neel temperature moderately increased from 18 K at 0.05% Fe to 25 K at 0.5% Fe. The magnetization (M) versus applied magnetic field (H) did not reach saturation for all samples up to 9 Tesla. The saturated magnetization (per Fe contents) is low and found to decreases linearly at a rate of (-35 emu/g-Fe) in a clear manifestation of the strengthening of the antiferromagnetic exchange interaction with increasing Fe contents.

  14. Local formation of a Heusler structure in CoFe-Al alloys

    NASA Astrophysics Data System (ADS)

    Wurmehl, S.; Jacobs, P. J.; Kohlhepp, J. T.; Swagten, H. J. M.; Koopmans, B.; Maat, S.; Carey, M. J.; Childress, J. R.

    2011-01-01

    We systematically study the changes in the local atomic environments of Co in CoFe-Al alloys as a function of Al content by means of nuclear magnetic resonance. We find that a Co2FeAl Heusler type structure is formed on a local scale. The observed formation of a highly spin-polarized Heusler compound may explain the improved magnetotransport properties in CoFe-Al based current-perpendicular-to-the-plane spin-valves.

  15. Calculation Of The Judd - Ofelt Parameters Of The ZnAl2O4: Eu3+

    NASA Astrophysics Data System (ADS)

    Constantin, S.; Stanciu, M. L.

    2012-12-01

    Zinc aluminate (ZnAl2O4) doped with rare earth metal ions has been investigated most frequently because of the unique luminescent properties resulting from its stability and high emission quantum yields. The present work is devoted to calculate the Judd-Ofelt parameters (Ω2, Ω4 and Ω6) of the trivalent europium doped in ZnAl2O4 spinel, the quality factor (Q) and the branching ratio (β).

  16. Fabrication and Photoelectric Properties of n-ZnO:Al/PdPc/p-Si Structures

    SciTech Connect

    Il'chuk, G.A.; Nikitin, S.E.; Nikolaev, Yu.A.; Rud', Yu.V.; Terukov, E.I.; Rud', V.Yu.

    2005-04-01

    Photosensitive n-ZnO:Al/PdPc/p-Si structures were fabricated by vacuum sublimation of palladium phthalocyanine with subsequent magnetron sputtering of ZnO:Al films on p-Si substrates. The current transport mechanisms and the photosensitivity of the structures obtained were investigated. It is shown that structures based on PdPc films are promising for photosensitive devices based on contacts between organic and inorganic semiconductors.

  17. Degradability Enhancement of Poly(Lactic Acid) by Stearate-Zn3Al LDH Nanolayers

    PubMed Central

    Eili, Mahboobeh; Shameli, Kamyar; Ibrahim, Nor Azowa; Yunus, Wan Md Zin Wan

    2012-01-01

    Recent environmental problems and societal concerns associated with the disposal of petroleum based plastics throughout the world have triggered renewed efforts to develop new biodegradable products compatible with our environment. This article describes the preparation, characterization and biodegradation study of poly(lactic acid)/layered double hydroxide (PLA/LDH) nanocomposites from PLA and stearate-Zn3Al LDH. A solution casting method was used to prepare PLA/stearate-Zn3Al LDH nanocomposites. The anionic clay Zn3Al LDH was firstly prepared by co-precipitation method from a nitrate salt solution at pH 7.0 and then modified by stearate anions through an ion exchange reaction. This modification increased the basal spacing of the synthetic clay from 8.83 Å to 40.10 Å. The morphology and properties of the prepared PLA/stearate-Zn3Al LDH nanocomposites were studied by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), thermogravimetric analysis (TGA), tensile tests as well as biodegradation studies. From the XRD analysis and TEM observation, the stearate-Zn3Al LDH lost its ordered stacking-structure and was greatly exfoliated in the PLA matrix. Tensile test results of PLA/stearate-Zn3Al LDH nanocomposites showed that the presence of around 1.0–3.0 wt % of the stearate-Zn3Al LDH in the PLA drastically improved its elongation at break. The biodegradation studies demonstrated a significant biodegradation rate improvement of PLA in the presence of stearate-Zn3Al LDH nanolayers. This effect can be caused by the catalytic role of the stearate groups in the biodegradation mechanism leading to much faster disintegration of nanocomposites than pure PLA. PMID:22942682

  18. Lattice location and thermal stability of implanted Fe in ZnO

    SciTech Connect

    Rita, E.; Wahl, U.; Correia, J.G.; Alves, E.; Soares, J.C.

    2004-11-22

    The emission channeling technique was applied to evaluate the lattice location of implanted {sup 59}Fe in single-crystalline ZnO. The angular distribution of {beta}{sup -} particles emitted by {sup 59}Fe was monitored with a position-sensitive electron detector, following 60 keV low dose (2.0x10{sup 13} cm{sup -2}) room-temperature implantation of the precursor isotope {sup 59}Mn. The emission patterns around the [0001], [1102],[1101], and [2113] directions revealed that following annealing at 800 deg. C, 95(8)% of the Fe atoms occupy ideal substitutional Zn sites with rms displacements of 0.06-0.09 A.

  19. Unstrained Epitaxial Zn-Substituted Fe3O4 Films for Ferromagnetic Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Ichimura, Takashi; Fujiwara, Kohei; Kushizaki, Takayoshi; Kanki, Teruo; Tanaka, Hidekazu

    2013-06-01

    A field-effect transistor has been fabricated utilizing an epitaxial film of unstrained zinc-substituted magnetite (Fe3O4) as the active channel. A thin film of Fe2.5Zn0.5O4 was grown on a lattice-matched MgO(001) substrate by pulsed-laser deposition and covered by a parylene gate insulator to dope charge carriers by a field effect. The device showed a field-effect mobility of 1.2 ×10-2 cm2 V-1 s-1 at 300 K, which is higher by a factor of 15 than those of the devices with strained Fe2.5Zn0.5O4 channels on perovskite-type substrates. The enhanced response to the gate electric field is useful in exploring gate-tunable magnetism in magnetite.

  20. Doping of inorganic materials in microreactors - preparation of Zn doped Fe3O4 nanoparticles.

    PubMed

    Simmons, M D; Jones, N; Evans, D J; Wiles, C; Watts, P; Salamon, S; Escobar Castillo, M; Wende, H; Lupascu, D C; Francesconi, M G

    2015-08-01

    Microreactor systems are now used more and more for the continuous production of metal nanoparticles and metal oxide nanoparticles owing to the controllability of the particle size, an important property in many applications. Here, for the first time, we used microreactors to prepare metal oxide nanoparticles with controlled and varying metal stoichiometry. We prepared and characterised Zn-substituted Fe3O4 nanoparticles with linear increase of Zn content (ZnxFe3-xO4 with 0 ≤ x ≤ 0.48), which causes linear increases in properties such as the saturation magnetization, relative to pure Fe3O4. The methodology is simple and low cost and has great potential to be adapted to the targeted doping of a vast array of other inorganic materials, allowing greater control on the chemical stoichiometry for nanoparticles prepared in microreactors. PMID:26099495

  1. Phase Separation kinetics in an Fe-Cr-Al alloy

    SciTech Connect

    Capdevila, C.; Miller, Michael K; Chao, J.

    2012-01-01

    The {alpha}-{alpha}{prime} phase separation kinetics in a commercial Fe-20 wt.% Cr-6 wt.% Al oxide dispersion-strengthened PM 2000{trademark} steel have been characterized with the complementary techniques atom probe tomography and thermoelectric power measurements during isothermal aging at 673, 708, and 748 K for times up to 3600 h. A progressive decrease in the Al content of the Cr-rich {alpha}{prime} phase was observed at 708 and 748 K with increasing time, but no partitioning was observed at 673 K. The variation in the volume fraction of the {alpha}{prime} phase well inside the coarsening regime, along with the Avrami exponent 1.2 and activation energy 264 kJ mol{sup -1}, obtained after fitting the experimental results to an Austin-Rickett type equation, indicates that phase separation in PM 2000{trademark} is a transient coarsening process with overlapping nucleation, growth, and coarsening stages.

  2. Importance of doping and frustration in itinerant Fe-doped Cr2Al

    DOE PAGESBeta

    Susner, M. A.; Parker, D. S.; Sefat, A. S.

    2015-05-12

    We performed an experimental and theoretical study comparing the effects of Fe-doping of Cr2Al, an antiferromagnet with a N el temperature of 670 K, with known results on Fe-doping of antiferromagnetic bcc Cr. (Cr1-xFex)2Al materials are found to exhibit a rapid suppression of antiferromagnetic order with the presence of Fe, decreasing TN to 170 K for x=0.10. Antiferromagnetic behavior disappears entirely at x≈0.125 after which point increasing paramagnetic behavior is exhibited. Moreover, this is unlike the effects of Fe doping of bcc antiferromagnetic Cr, in which TN gradually decreases followed by the appearance of a ferromagnetic state. Theoretical calculations explainmore » that the Cr2Al-Fe suppression of magnetic order originates from two effects: the first is band narrowing caused by doping of additional electrons from Fe substitution that weakens itinerant magnetism; the second is magnetic frustration of the Cr itinerant moments in Fe-substituted Cr2Al. In pure-phase Cr2Al, the Cr moments have an antiparallel alignment; however, these are destroyed through Fe substitution and the preference of Fe for parallel alignment with Cr. This is unlike bulk Fe-doped Cr alloys in which the Fe anti-aligns with the Cr atoms, and speaks to the importance of the Al atoms in the magnetic structure of Cr2Al and Fe-doped Cr2Al.« less

  3. Fluorescence of Zn-Al-Eu ternary layered hydroxide response to phenylalanine

    NASA Astrophysics Data System (ADS)

    Chen, Yufeng; Li, Fei; Yu, Gensheng; Yang, Xiaojing

    2012-02-01

    We reported the fluorescence of a Zn-Al-Eu ternary layered double hydroxide (LDH) response to an amino acid (phenylalanine) for the first time. As shown in fluorescence, the red emissions attributed to 5D 0- 7F J transitions ( J = 1, 2, 3, 4) of Eu 3+ ions were quenched by the phenylalanine (Phe), and a strong blue emission at around 445 nm appeared. The fluorescent changes may be due to ligand-to-metal charges transfer, which was caused by the interaction between the Zn-Al-Eu LDH and Phe. This interaction was manifested by markedly different chemical shift positions of the Zn 3p 3/2, Al 2p, Eu 4d 3/2, O 1s, and C 1s peaks in the XPS spectra from those of the Zn-Al-Eu LDH and Zn-Al-Eu/Phe composite. Furthermore, the interaction between the LDH and Phe was supported by the results of X-ray diffraction (XRD) measurements, Fourier transform infrared (FT-IR) spectra, and thermogravimetric and differential thermogravimetric (TG-DTG) analysis. The fluorescence of Zn-Al-Eu LDH response to Phe may be potential application in biological techniques.

  4. Platelets to rings: Influence of sodium dodecyl sulfate on Zn-Al layered double hydroxide morphology

    SciTech Connect

    Yilmaz, Ceren; Unal, Ugur; Yagci Acar, Havva

    2012-03-15

    In the current study, influence of sodium dodecyl sulfate (SDS) on the crystallization of Zn-Al layered double hydroxide (LDH) was investigated. Depending on the SDS concentration coral-like and for the first time ring-like morphologies were obtained in a urea-hydrolysis method. It was revealed that the surfactant level in the starting solution plays an important role in the morphology. Concentration of surfactant equal to or above the anion exchange capacity of the LDH is influential in creating different morphologies. Another important parameter was the critical micelle concentration (CMC) of the surfactant. Surfactant concentrations well above CMC value resulted in ring-like structures. The crystallization mechanism was discussed. - Graphical abstract: Dependence of ZnAl LDH Morphology on SDS concentration. Highlights: Black-Right-Pointing-Pointer In-situ intercalation of SDS in ZnAl LDH was achieved via urea hydrolysis method. Black-Right-Pointing-Pointer Morphology of ZnAl LDH intercalated with SDS depended on the SDS concentration. Black-Right-Pointing-Pointer Ring like morphology for SDS intercalated ZnAl LDH was obtained for the first time. Black-Right-Pointing-Pointer Growth mechanism was discussed. Black-Right-Pointing-Pointer Template assisted growth of ZnAl LDH was proposed.

  5. Reoxidation of Aluminum in Fe- Al- M (M = C, Mn, and Ti) melts with CaO-Al2 O3-Fe t O (3 mass pct) slags

    NASA Astrophysics Data System (ADS)

    Lee, Kwang Ro; Suito, Hideaki

    1996-06-01

    An Fe-0.01 to 0.5 mass pct Al alloy and an Fe-0.003 to 0.71 mass pct Al-1 mass pct M (M = C, Mn, and Ti) alloy were reoxidized with the CaO-Al2O3-FetO (3 mass pct) slags at 1873 K in an Al2O3 or CaO crucible for 5 and 60 minutes. The contents of acid-insoluble Al, total O, and alloying element M in metal as well as those of M and FetO in slag were measured as a function of total Al content. On the basis of the present and previous results for Fe- Al- Te alloys, the effect of alloying elements on the degree of supersaturation with respect to the Al2O3 precipitation was studied. As a result, the supersaturation phenomenon was observed in all experiments at 5 minutes, but in the experiments at 60 minutes, it was observed only in Fe- Al and Fe- Al- Ti alloys. No supersaturation was observed in the reoxidation of Si in Fe-0.13 to 0.98 mass pct Si alloys with the CaO-SiO2-FetO (3 mass pct) slags in a CaO crucible at 5 and 60 minutes.

  6. Bonding of WC with an iron aluminide (FeAl) intermetallic

    SciTech Connect

    Schneibel, J.H.; Subramanian, R.

    1996-08-01

    FeAl, which has high oxidation and sulfidation resistance, was shown to be thermodynamically compatible with WC. Calculations indicate that soly. of WC in liq. Fe-40at.%Al at 1450 C is about 2 at.%. Since liquid FeAl wets WC very well, the WC/FeAl system lends itself to liquid-phase sintering, resulting in close to theoretical densities. Almost fully dense cermets with 20.6 wt% FeAl binder were produced. With one-step infiltration, 98% dense cermets with only 7 wt% FeAl binder were fabricated. RT bend strengths and fracture toughness for WC-20.6 wt% FeAl reached 1680 MPa and 22 MPa{center_dot}m{sup 1/2}. Ductile binder fracture was observed on the fracture surfaces. Pores containing oxide inclusions were found, suggesting that improvements in processing are likely to further improve the mechanical properties. Insufficient process control may explain why WC/FeAlNi cermets did not show improved mechanical properties, although Ni strengthens FeAl. For WC bonded with FeAl, mechanical properties were measured at RT and 800 C. Bend strengths at 800 C in air increased with WC volume fraction, and fracture toughness were higher than at RT.

  7. Impact behavior of FeAl alloy FA-350

    SciTech Connect

    Alexander, D.J.

    1994-09-01

    The tensile properties and impact behavior of the iron aluminide FeAl-type alloy FA-350 [Fe-35.8Al-0.05Zr-0.24B (at. %)] have been studied over the temperature range of {minus}100 to 800C. Half-size Charpy specimens were either oil quenched from 700C or furnace cooled. The energy absorbed during the impact test showed a maximum value at 100 to 200C, with decreasing energy as the temperature was increased, for both heat treatments. The furnace-cooled material had greater energy absorption than the oil-quenched material. The tensile tests showed increasing ductility (as measured by total elongation) with increasing temperature. The furnace-cooled material had lower strength and higher ductility than the oil-quenched material. Fractographic examination of the oil-quenched impact specimens revealed that several different fracture modes operated, depending on the test temperature. Fracture occurred by intergranular and quasicleavage fracture at low temperatures, predominantly quasicleavage at intermediate temperatures, and intergranular fracture at 800C. For the furnace-cooled material fracture was predominantly quasicleavage at all temperatures. The higher ductility and energy absorption for the furnace-cooled material is believed to be the result of softening due to a decrease in the retained vacancy concentration.

  8. Weldability of Fe[sub 3]Al-type Aluminide

    SciTech Connect

    David, S.A.; Zacharia, T. )

    1993-05-01

    An investigation was carried out to determine the weldability of a series of Fe[sub 3]Al-type alloys. Autogenous welds were made on thin sheets of iron aluminide alloys using gas tungsten arc (GTA) and electron beam (EB) welding processes at different travel speeds and power levels. The results indicate that although these alloys can be successfully welded using the EB welding process, some compositions may hot crack during GTA welding. Boron and zirconium additions have been found to promote hot cracking in these alloys. Among the alloys investigated, Fe[sub 3]Al modified with chromium, niobium and carbon (FA-129) showed the most promise for good weldability. Hot-cracking severity of this alloy was further investigated using the Sigmajig test. The minimum threshold stress of 25 ksi measured is within the material range of other aluminides and some commercial stainless steels. Also, some of these alloys exhibited a tendency for cold cracking. This is related to severe hydrogen embrittlement associated with this class of alloys.

  9. Al3+ environments in nanostructured ZnAl2O4 and their effects on the luminescence properties.

    PubMed

    da Silva, Alison A; Gonçalves, Agnaldo S; Davolos, Marian R; Santagneli, Silvia H

    2008-11-01

    Single-phase zinc aluminate (ZnAl2O4) with the spinel structure was successfully obtained by the Pechini method at different calcining temperatures for 4 hours. The nanoparticles are highly crystalline with no impurities related to ZnO or Al2O3 residues. The microstructural environment of aluminium ions changes with heat treatment temperature, as observed by Fourier transform infrared spectroscopy. The spinel structure might present two different AlO6 sites as evidenced by 27Al solid-state magic-angle-spinning nuclear magnetic resonance spectra. Some AlO4 sites were also detected for samples calcined at a temperature lower than 900 degrees C. The photoluminescence spectra show that the emission can be tuned depending on the calcining temperature. This effect was discussed on the basis of symmetry and oxygen vacancies. PMID:19198290

  10. Elastic, phonon and thermodynamic properties of ZnAl2O4 and ZnAl2S4 compounds from first-principles calculations

    NASA Astrophysics Data System (ADS)

    Yang, Chun-Yan; Dai, Fu-Ping; Zhang, Rong; Li, Liu-Hui; Zhou, Qian

    2015-02-01

    First-principles calculations are performed to investigate the elastic, phonon and thermodynamic properties of ZnAl2O4 and ZnAl2S4 structures. The equations of state are fitted by a four-parameter Birch-Murnaghan equation upon the first-principles energy vs. volume data. Three independent elastic constants c11, c12 and c44 at zero pressure are determined by strain energy vs. strain relationships, and the two structures are both mechanically stable. Elastic properties including bulk moduli, shear moduli, Young's moduli, Poisson's ratios and anisotropy values for both phases are estimated by Voigt-Reuss-Hill averaging scheme. The mechanical properties such as ductility and brittleness are further analyzed. The density functional perturbation theory is utilized to calculate the phonon properties and both phases are found to be dynamically stable. The phonon and Debye models are used to predict the thermodynamic properties such as the Gibbs free energies, entropies and specific heats at constant pressure for ZnAl2O4 and ZnAl2S4 compounds.

  11. Origins of low resistivity in Al ion-implanted ZnO bulk single crystals

    SciTech Connect

    Oga, T.; Izawa, Y.; Kuriyama, K.; Kushida, K.; Kinomura, A.

    2011-06-15

    The origins of low resistivity in Al ion-implanted ZnO bulk single crystals are studied by combining Rutherford backscattering spectroscopy (RBS), nuclear reaction analysis (NRA), photoluminescence (PL), and Van der Pauw methods. The Al-ion implantation (peak concentration: 2.6 x 10{sup 20}cm{sup -3}) into ZnO is performed using a multiple-step energy. The resistivity decreases from {approx}10{sup 4{Omega}} cm for un-implanted ZnO to 1.4 x 10{sup -1{Omega}} cm for as-implanted, and reaches 6.0 x 10{sup -4{Omega}} cm for samples annealed at 1000 deg. C. RBS and NRA measurements for as-implanted ZnO suggest the existence of the lattice displacement of Zn (Zn{sub i}) and O (O{sub i}), respectively. After annealing at 1000 deg. C, the Zn{sub i} related defects remain and the O{sub i} related defects disappear. The origin of the low resistivity in the as-implanted sample is attributed to the Zn{sub i} ({approx}30 meV [Look et al., Phys. Rev. Lett. 82, 2552 (1999)]). In contrast, the origin of the low resistivity in the sample annealed at 1000 deg. C is assigned to both of the Zn{sub i} related defects and the electrically activated Al donor. A new PL emission appears at around 3.32 eV after annealing at 1000 deg. C, suggesting electrically activated Al donors.

  12. Characterization and study of antibacterial activity of spray pyrolysed ZnO:Al thin films

    NASA Astrophysics Data System (ADS)

    Manoharan, C.; Pavithra, G.; Bououdina, M.; Dhanapandian, S.; Dhamodharan, P.

    2016-08-01

    Aluminum-doped zinc oxide (ZnO:Al) thin films were deposited onto glass substrates using spray pyrolysis technique with the substrate temperature of 400 °C. X-ray diffraction analysis indicated that the films were polycrystalline with hexagonal wurtzite structure preferentially oriented along (002) direction. Surface morphology of the films obtained by scanning electron microscopy showed that the grains were of nanoscale size with porous nature for 6 at.% of Al. Atomic force microscopy observations revealed that the particles size and surface roughness of the films decreased with Al-doping. Optical measurements indicated that ZnO:Al (6 at.%) exhibited a band gap of 3.11 eV, which is lower than that of pure ZnO film, i.e. 3.42 eV. Photoluminescence analysis showed weak NBE emission at 396 nm for Al-doped films. The low resistivity, high hall mobility and carrier concentration values were obtained at a doping ratio of 6 at.% of Al. The effective incorporation of 6 at.% of Al into ZnO lattice by occupying Zn sites yielded a well-pronounced antibacterial activity against Staphylococcus aureus.

  13. Characterization and study of antibacterial activity of spray pyrolysed ZnO:Al thin films

    NASA Astrophysics Data System (ADS)

    Manoharan, C.; Pavithra, G.; Bououdina, M.; Dhanapandian, S.; Dhamodharan, P.

    2015-08-01

    Aluminum-doped zinc oxide (ZnO:Al) thin films were deposited onto glass substrates using spray pyrolysis technique with the substrate temperature of 400 °C. X-ray diffraction analysis indicated that the films were polycrystalline with hexagonal wurtzite structure preferentially oriented along (002) direction. Surface morphology of the films obtained by scanning electron microscopy showed that the grains were of nanoscale size with porous nature for 6 at.% of Al. Atomic force microscopy observations revealed that the particles size and surface roughness of the films decreased with Al-doping. Optical measurements indicated that ZnO:Al (6 at.%) exhibited a band gap of 3.11 eV, which is lower than that of pure ZnO film, i.e. 3.42 eV. Photoluminescence analysis showed weak NBE emission at 396 nm for Al-doped films. The low resistivity, high hall mobility and carrier concentration values were obtained at a doping ratio of 6 at.% of Al. The effective incorporation of 6 at.% of Al into ZnO lattice by occupying Zn sites yielded a well-pronounced antibacterial activity against Staphylococcus aureus.

  14. Luminescence Spectra of ZnAl 2 O 4 {:}Cr 3+ Spinel Nanopowders

    NASA Astrophysics Data System (ADS)

    Luc, H. H.; Nguyen, T. K.; Nguyen, V. M.; Suchocki, A.; Kamiñska, A.; Le, V. K.; Nguyen, V. H.; Luong, T. T.

    2002-12-01

    The synthetic ZnAl 2 O 4 spinels doped with Cr 3+ ions are prepared from ZnSO,dwi{4}>, Al 2 (SO 4 ) 3 , and Cr 2 (SO 4 ) 3 . The spinel single phase is detected from X-ray diffraction. Luminescence properties of Cr 3+ in ZnAl 2 O 4 were studied by low temperature luminescence and decay measurements. Four luminescence lines at 14570, 14520, 14460, and 14330 cm -1 were found to originate from structure distortion and the line at 14175 cm -1 - from chromium pairs. The broad emission band at about 13540 cm -1 is considered to arise from a new Cr 3+ center in ZnCr 2 O 4 .

  15. Adhesion of Escherichia coli to nano-Fe/Al oxides and its effect on the surface chemical properties of Fe/Al oxides.

    PubMed

    Liu, Zhao-Dong; Li, Jiu-Yu; Jiang, Jun; Hong, Zhi-Neng; Xu, Ren-Kou

    2013-10-01

    We investigated the adhesion of Escherichia coli to α-Fe2O3 and γ-Al2O3 and the effects of adhesion on the surface properties of the oxides in batch experiments, where we conducted potentiometric titration, zeta potential measurements, and FTIR spectroscopy. The adhesion isotherms fitted a Langmuir equation well. γ-Al2O3 had a higher adhesion capacity than α-Fe2O3 because of the higher positive charge on γ-Al2O3. The adhesion of E. coli to Fe/Al oxides decreased with increasing pH. Adhesion increased with increasing NaCl concentration, reaching its maximum at 0.05M for α-Fe2O3 and at 0.1M for γ-Al2O3, after which it decreased with further increases in NaCl concentration. Therefore, the electrostatic force plays an important role in the adhesion of E. coli to Fe/Al oxides. The zeta potential-pH curves of the binary-system fell between that for bacteria and those for Fe/Al oxides. Thus, overlapping of the diffuse layers of the electric double layers on the negatively-charged E. coli and positively-charged Fe/Al oxides reduced the effective surface charge density of the minerals and bacteria. E. coli adhesion decreased the point of zero salt effect and the isoelectric point of the Fe/Al oxides. The FTIR spectra indicated that non-electrostatic force also contributed to the interaction between E. coli and Fe/Al oxides, in addition to the electrostatic force between them. PMID:23732807

  16. Ultrasonic spray pyrolysis growth of ZnO and ZnO:Al nanostructured films: Application to photocatalysis

    SciTech Connect

    Kenanakis, G.; Katsarakis, N.

    2014-12-15

    Highlights: • Al–ZnO thin films and nanostructures were obtained by ultrasonic spray pyrolysis. • The texture and morphology of the samples depend on the deposition parameters. • The photocatalytic degradation of stearic acid was studied upon UV-A irradiation. - Abstract: Pure and Al-doped ZnO (Al = 1, 3, 5%) nanostructured thin films were grown at 400 °C on glass substrates by ultrasonic spray pyrolysis, a simple, environmental-friendly and inexpensive method, using aqueous solutions as precursors. The structural and morphological characteristics of the samples depend drastically on deposition parameters; ZnO nanostructured films, nanopetals and nanorods were systematically obtained by simply varying the precursor solution and/or the spraying time. Transmittance measurements have shown that all samples are transparent in the visible wavelength region. Finally, the photocatalytic properties of the samples were investigated against the degradation of stearic acid under UV-A light illumination (365 nm); both pure and Al-doped ZnO nanostructured thin films show good photocatalytic activity regarding the degradation of stearic acid, due to their good crystallinity and large surface area.

  17. Novel ZnO:Al contacts to CdZnTe for X- and gamma-ray detectors

    PubMed Central

    Roy, U. N.; Mundle, R. M.; Camarda, G. S.; Cui, Y.; Gul, R.; Hossain, A.; Yang, G.; Pradhan, A. K.; James, R. B.

    2016-01-01

    CdZnTe (CZT) has made a significant impact as a material for room-temperature nuclear-radiation detectors due to its potential impact in applications related to nonproliferation, homeland security, medical imaging, and gamma-ray telescopes. In all such applications, common metals, such as gold, platinum and indium, have been used as electrodes for fabricating the detectors. Because of the large mismatch in the thermal-expansion coefficient between the metal contacts and CZT, the contacts can undergo stress and mechanical degradation, which is the main cause for device instability over the long term. Here, we report for the first time on our use of Al-doped ZnO as the preferred electrode for such detectors. The material was selected because of its better contact properties compared to those of the metals commonly used today. Comparisons were conducted for the detector properties using different contacts, and improvements in the performances of ZnO:Al-coated detectors are described in this paper. These studies show that Al:ZnO contacts to CZT radiation detectors offer the potential of becoming a transformative replacement for the common metallic contacts due to the dramatic improvements in the performance of detectors and improved long-term stability. PMID:27216387

  18. Novel ZnO:Al contacts to CdZnTe for X- and gamma-ray detectors

    NASA Astrophysics Data System (ADS)

    Roy, U. N.; Mundle, R. M.; Camarda, G. S.; Cui, Y.; Gul, R.; Hossain, A.; Yang, G.; Pradhan, A. K.; James, R. B.

    2016-05-01

    CdZnTe (CZT) has made a significant impact as a material for room-temperature nuclear-radiation detectors due to its potential impact in applications related to nonproliferation, homeland security, medical imaging, and gamma-ray telescopes. In all such applications, common metals, such as gold, platinum and indium, have been used as electrodes for fabricating the detectors. Because of the large mismatch in the thermal-expansion coefficient between the metal contacts and CZT, the contacts can undergo stress and mechanical degradation, which is the main cause for device instability over the long term. Here, we report for the first time on our use of Al-doped ZnO as the preferred electrode for such detectors. The material was selected because of its better contact properties compared to those of the metals commonly used today. Comparisons were conducted for the detector properties using different contacts, and improvements in the performances of ZnO:Al-coated detectors are described in this paper. These studies show that Al:ZnO contacts to CZT radiation detectors offer the potential of becoming a transformative replacement for the common metallic contacts due to the dramatic improvements in the performance of detectors and improved long-term stability.

  19. Novel ZnO:Al contacts to CdZnTe for X- and gamma-ray detectors.

    PubMed

    Roy, U N; Mundle, R M; Camarda, G S; Cui, Y; Gul, R; Hossain, A; Yang, G; Pradhan, A K; James, R B

    2016-01-01

    CdZnTe (CZT) has made a significant impact as a material for room-temperature nuclear-radiation detectors due to its potential impact in applications related to nonproliferation, homeland security, medical imaging, and gamma-ray telescopes. In all such applications, common metals, such as gold, platinum and indium, have been used as electrodes for fabricating the detectors. Because of the large mismatch in the thermal-expansion coefficient between the metal contacts and CZT, the contacts can undergo stress and mechanical degradation, which is the main cause for device instability over the long term. Here, we report for the first time on our use of Al-doped ZnO as the preferred electrode for such detectors. The material was selected because of its better contact properties compared to those of the metals commonly used today. Comparisons were conducted for the detector properties using different contacts, and improvements in the performances of ZnO:Al-coated detectors are described in this paper. These studies show that Al:ZnO contacts to CZT radiation detectors offer the potential of becoming a transformative replacement for the common metallic contacts due to the dramatic improvements in the performance of detectors and improved long-term stability. PMID:27216387

  20. Thermodynamic Assessment of the Aluminum Corner of the Al-Fe-Mn-Si System

    NASA Astrophysics Data System (ADS)

    Lacaze, Jacques; Eleno, Luiz; Sundman, Bo

    2010-09-01

    A new assessment of the aluminum corner of the quaternary Al-Fe-Mn-Si system has been made that extends beyond the COST-507 database. This assessment makes use of a recent, improved description of the ternary Al-Fe-Si system. In the present work, modeling of the Al-rich corner of the quaternary Al-Fe-Mn-Si system has been carried out by introducing Fe solubility into the so-called alpha-AlMnSi and beta-AlMnSi phases of the Al-Mn-Si system. A critical review of the data available on the quaternary system is presented and used for the extension of the description of these ternary phases into the quaternary Al-Fe-Mn-Si.

  1. Influence of testing environment on the room temperature ductility of FeAl alloys

    NASA Technical Reports Server (NTRS)

    Gaydosh, D. J.; Nathal, M. V.

    1990-01-01

    The effects of testing atmospheres (air, O2, N2, and vacuum) on the room-temperature ductility of Fe-40Al, Fe-40Al-0.5B, and Fe-50Al alloys were investigated. The results confirmed the decrease in room-temperature ductility of Fe-rich FeAl alloys by the interaction of the aluminide with water vapor, reported previously by Liu et al. (1989). The highest ductilities were measured in the atmosphere with the lowest moisture levels, i.e., in vacuum. It was found that significant ductility is still restricted to Fe-rich alloys (Fe-40Al), as the Fe-50Al alloy remained brittle under all testing conditions. It was also found that slow cooling after annealing was beneficial, and the effect was additive to the environmental effect. The highest ductility measurements in this study were 9 percent elongation in furnace-cooled Fe-40Al and in Fe-40Al-0.5B, when tested in vacuum.

  2. Designing polar and magnetic oxides: Zn2FeTaO6--in search of multiferroics.

    PubMed

    Li, Man-Rong; Stephens, Peter W; Retuerto, Maria; Sarkar, Tapati; Grams, Christoph P; Hemberger, Joachim; Croft, Mark C; Walker, David; Greenblatt, Martha

    2014-06-18

    Polar oxides are technically of great interest but difficult to prepare. Our recent discoveries predicted that polar oxides can be synthesized in the corundum-derivative A2BB'O6 family with unusually small cations at the A-site and a d(0) electron configuration ion at B'-site. When magnetic transition-metal ions are incorporated more interesting polar magnetic oxides can form. In this work we experimentally verified this prediction and prepared LiNbO3 (LN)-type polar magnetic Zn2FeTaO6 via high pressure and temperature synthesis. The crystal structure analysis indicates highly distorted ZnO6 and (Fe/Ta)O6 octahedra, and an estimated spontaneous polarization (PS) of ∼50 μC/cm(2) along the c-axis was obtained from point charge model calculations. Zn2Fe(3+)Ta(5+)O6 has a lower magnetic transition temperature (TN ∼ 22 K) than the Mn2FeTaO6 analogue but is less conductive. The dielectric and polarization measurements indicate a potentially switchable component. PMID:24841411

  3. Influence of calcination on the adsorptive removal of phosphate by Zn-Al layered double hydroxides from excess sludge liquor.

    PubMed

    Cheng, Xiang; Huang, Xinrui; Wang, Xingzu; Sun, Dezhi

    2010-05-15

    The influence of calcination of Zn-Al layered double hydroxides (LDHs) on their phosphate adsorption capacity was studied in order to improve phosphorus removal from an excess sludge liquor. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), thermogravimetry-differential scanning calorimetry (TG-DSC) and nitrogen adsorption-desorption were employed to characterize the raw Zn-Al and the calcined products. The results reveal that the Zn-Al LDHs evolved to a phase of mixed metal oxides with the calcination temperature increasing to 300 degrees C and finally to spinel ZnAl(2)O(4) at 600 degrees C. When the Zn-Al was calcined at 300 degrees C, the interlayer carbonate ions were removed and the greatest BET surface area of 81.20 m(2)/g was achieved. The tested phosphate adsorption capacities of the raw and calcined Zn-Al were closely related to the evolution of physicochemical properties of the LDHs during the calcination. The Zn-Al-300 (Zn-Al LDHs calcined at 300 degrees C) exhibited the highest P uptake of 41.26 mg P/g in 24h. The phosphate adsorption by the raw Zn-Al and the Zn-Al-300 both follows a pseudo-second-order kinetic model; the adsorption isotherms show a good fit with a Langmuir-type equation. PMID:20060217

  4. Structural investigation of the (010) surface of the Al13 Fe4 catalyst.

    PubMed

    Ledieu, J; Gaudry, É; Loli, L N Serkovic; Villaseca, S Alarcón; de Weerd, M-C; Hahne, M; Gille, P; Grin, Y; Dubois, J-M; Fournée, V

    2013-02-15

    We have investigated the structure of the Al(13)Fe(4)(010) surface using both experimental and ab initio computational methods. The results indicate that the topmost surface layers correspond to incomplete puckered (P) planes present in the bulk crystal structure. The main building block of the corrugated termination consists of two adjacent pentagons of Al atoms, each centered by a protruding Fe atom. These motifs are interconnected via additional Al atoms referred to as "glue" atoms which partially desorb above 873 K. The surface structure of lower atomic density compared to the bulk P plane is explained by a strong Fe-Al-Fe covalent polar interaction that preserves intact clusters at the surface. The proposed surface model with identified Fe-containing atomic ensembles could explain the Al(13)Fe(4) catalytic properties recently reported in line with the site-isolation concept [M. Armbrüster et al., Nat. Mater. 11, 690 (2012)]. PMID:25166385

  5. Oxidation Control of Atmospheric Plasma Sprayed FeAl Intermetallic Coatings Using Dry-Ice Blasting

    NASA Astrophysics Data System (ADS)

    Song, Bo; Dong, Shujuan; Coddet, Pierre; Hansz, Bernard; Grosdidier, Thierry; Liao, Hanlin; Coddet, Christian

    2013-03-01

    The performance of atmospheric plasma sprayed FeAl coatings has been remarkably limited because of oxidation and phase transformation during the high-temperature process of preparation. In the present work, FeAl intermetallic coatings were prepared by atmospheric plasma spraying combined with dry-ice blasting. The microstructure, oxidation, porosity, and surface roughness of FeAl intermetallic coatings were investigated. The results show that a denser FeAl coating with a lower content of oxide and lower degree of phase transformation can be achieved because of the cryogenic, the cleaning, and the mechanical effects of dry-ice blasting. The surface roughness value decreased, and the adhesive strength of FeAl coating increased after the application of dry-ice blasting during the atmospheric plasma spraying process. Moreover, the microhardness of the FeAl coating increased by 72%, due to the lower porosity and higher dislocation density.

  6. Temperature- and frequency-dependent dielectric behaviors of insulator/semiconductor (Al2O3/ZnO) nanolaminates with various ZnO thicknesses

    NASA Astrophysics Data System (ADS)

    Li, Jin; Bi, Xiaofang

    2016-07-01

    Al2O3/ZnO nanolaminates (NLs) with various ZnO sublayer thicknesses were prepared by atomic layer deposition. The Al2O3 sublayers are characterized as amorphous and the ZnO sublayers have an oriented polycrystalline structure. As the ZnO thickness decreases to a certain value, each NL exhibits a critical temperature at which its dielectric constant starts to rise quickly. Moreover, this temperature increases as the ZnO thickness is decreased further. On the other hand, the permittivity demonstrates a large value of several hundred at a frequency  ⩽1000 Hz, followed by a steplike decrease at a higher frequency. The change in the cut-off frequency with ZnO thickness is characterized by a hook function. It is revealed that the Coulomb confinement effect becomes predominant in the dielectric behaviors of the NLs with very thin ZnO. As the ZnO thickness decreases to about the same as or even smaller than the Bohr radius of ZnO, a great change in the carrier concentration and effective mass of ZnO is induced, which is shown to be responsible for the peculiar dielectric behaviors of Al2O3/ZnO with very thin ZnO. These findings provide insight into the prevailing mechanisms to optimize the dielectric properties of semiconductor/insulator laminates with nanoscale sublayer thickness.

  7. Thermoelasticity of Fe3+- and Al-bearing bridgmanite: Effects of iron spin crossover

    NASA Astrophysics Data System (ADS)

    Shukla, Gaurav; Cococcioni, Matteo; Wentzcovitch, Renata M.

    2016-06-01

    We report ab initio (LDA + Usc) calculations of thermoelastic properties of ferric iron (Fe3+)- and aluminum (Al)-bearing bridgmanite (MgSiO3 perovskite), the main Earth forming phase, at relevant pressure and temperature conditions and compositions. Three coupled substitutions, namely, [Al]Mg-[Al]Si, [Fe3+]Mg-[Fe3+]Si, and [Fe3+]Mg-[Al]Si have been investigated. Aggregate elastic moduli and sound velocities are successfully compared with limited experimental data available. In the case of [Fe3+]Mg-[Fe3+]Si substitution, the high-spin (S = 5/2) to low-spin (S = 1/2) crossover in [Fe3+]Si induces a volume collapse and elastic anomalies across the transition region. However, the associated anomalies should disappear in the presence of aluminum in the most favorable substitution, i.e., [Fe3+]Mg-[Al]Si. Calculated elastic properties along a lower mantle model geotherm suggest that the elastic behavior of bridgmanite with simultaneous substitution of Fe2O3 and Al2O3 in equal proportions or with Al2O3 in excess should be similar to that of (Mg,Fe2+)SiO3 bridgmanite. However, excess of Fe2O3 should produce elastic anomalies in the crossover pressure region.

  8. Effect of aging on the fatigue crack growth kinetics of an Al-Zn-Mg-Cu alloy in two directions

    SciTech Connect

    Alpay, S.P.; Guerbuez, R. . Dept. of Metallurgical Engineering)

    1994-02-15

    There have been investigations discussing the effect of aging condition, and thereby the microstructure, on the fatigue crack growth characteristics of precipitation hardening alloys. Lindigkeit et al.., testing an Al-Zn-Mg-Cu alloy of composition corresponding to the commercial alloy 7075 concluded that the crack propagation resistance of underaged microstructures with shearable precipitates is significantly higher than overaged samples of same strength containing non-shearable particles. They reported that this behavior cannot be explained on the basis of slip reversibility alone. A similar conclusion is drawn by Zaiken and Ritchie from investigations on the effect of microstructure on the fatigue crack growth rate of an 7150 aluminum alloy, which is a somewhat high-purity version of the alloy 7050, with lower Fe and Si contents. It is also interesting that aging conditions showing high resistance to fatigue crack growth at low [Delta]K regimes, do not necessarily retain their superiority at medium and high stress intensity ranges.

  9. Passivation analysis of silicon surfaces via sol—gel derived Al-rich ZnO film

    NASA Astrophysics Data System (ADS)

    Khan, Firoz; Baek, Seong-Ho; Kim, Jae Hyun

    2015-01-01

    Electronic recombination losses can be reduced via passivation of silicon surfaces. Most techniques available in the literature are either not cost effective or not applicable for solar cell applications. We investigate low cost sol-gel derived Al-rich zinc oxide (ZnO:Al) film and its effective passivation of p-type silicon surfaces. Herein, we present the elemental composition of the film and interfacial structure of ZnO:Al/Si using FTIR, XPS, TEM, and SIMS characterizations. ZnO:Al is polycrystalline and contains some very small amorphous regions of Al2O3. At the ZnO:Al/c-Si interface, a thin SiOx layer with a thickness of ˜6 nm is formed. The XPS analyses reveal that the Al/Zn molar ratio in the ZnO:Al increases from ˜10% at the surface to ˜80% at the ZnO:Al/c-Si interface. The hydrogen content also gradually increases from the surface to the interface. The FTIR absorption area corresponding to the Si-H bonding is ˜2.89 au. The obtained hydrogen concentration is ˜3.93 × 1022 atoms cm-3. A fixed negative charge is created by ZnO:Al on ZnO//SiOx interface. The thermal equilibrium was established between Si and ZnO:Al through SiOx by electron tunneling current. Here, the c-Si may be passivated for two reasons: (i) Al creates defects on the ZnO:Al/c-Si interface and H is attached to the defects (dangling bonds) and (ii) due to the field effect passivation via the negative charged ZnO:Al film.

  10. Effect of nitrogen upon structural and magnetic properties of FePt in FePt/AlN multilayer structures

    SciTech Connect

    Gao, Tenghua Zhang, Cong; Sannomiya, Takumi; Muraishi, Shinji; Nakamura, Yoshio; Shi, Ji

    2014-09-01

    This paper investigates the effect of the addition of nitrogen in FePt layers for ultrathin FePt/AlN multilayer structures. X-ray diffraction results reveal that a compressive stress relaxation occurs after annealing owing to the release of interstitial nitrogen atoms in the FePt layers. The introduction of nitrogen also induces a large in-plane compressive strain during grain growth not seen in FePt deposited without nitrogen. This strain is considered to decrease the driving force for (111) grain growth and FePt ordering.

  11. Anisotropic hot deformed magnets prepared from Zn-coated MRE-Fe-B ribbon powder

    SciTech Connect

    Tang, W; Zhou, L; Sun, K W; Dennis, K W; Kramer, M J; Anderson, I E; McCallum, R W

    2014-05-07

    Milled melt-spun ribbon flake of MRE-Fe-B coated with Zn coating using a vapor transport technique was found to have significant increase in coercivity without degrading the magnetization when the Zn thickness and heat treatment were optimized. Magnetic measurements show that 0.5–1 wt. % Zn coating increases the coercivity about 1 kOe over the initial ribbon powder. After vacuum hot deformation (VHD), the VHD magnet with Zn coating of 0.5 wt. % results in a nearly 3 kOe higher coercivity than an un-coated alloy magnet. An optimized VHD magnet with 0.5 wt. % Zn coating obtains a coercivity of 11.2 kOe and (BH)max of 23.0 MGOe, respectively. SEM and TEM microstructures analysis demonstrates that the Zn coating on the surface of ribbon powder has diffused along the intergranular boundaries after the ribbon powder was annealed at 750 °C for 30 min or was hot deformed at 700–750 °C.

  12. Magnetostrictive behaviors of Fe-Al(001) single-crystal films under rotating magnetic fields

    NASA Astrophysics Data System (ADS)

    Kawai, Tetsuroh; Abe, Tatsuya; Ohtake, Mitsuru; Futamoto, Masaaki

    2016-05-01

    Magnetostrictive behaviors of Fe100-x - Alx(x = 0 - 30 at.%)(001) single-crystal films under rotating magnetic fields are investigated along the two different crystallographic orientations, [100] and [110]. The behaviors of Fe and Fe90Al10 films show bath-tub like waveform along [100], easy magnetization axis, and triangular waveform along [110], hard magnetization axis, with respect to their four-fold magnetic anisotropy. On the other hand, the behaviors of Fe80Al20 film are different from those of Fe or Fe90Al10 film. The output of the film along [100] shows a strong magnetic field dependence. The Fe70Al30 film shows similar magnetostrictive behaviors along both [100] and [110] reflecting its magnetic properties, which are almost same for the both directions. The growth of ordered phase (B2) in Fe80Al20 and Fe70Al30 films is considered to have affected their magnetostrictive behaviors. The Al content dependence on λ100 and λ111 values shows similar tendency to that reported for the bulk samples but the values are slightly different. The Fe90Al10(001) single-crystal film shows a large magnetostriction along [100] under a very small magnetic field of 0.02 kOe, which is comparable to the saturated one, and changes the value abruptly in relation to the angle of applied magnetic field.

  13. Structure and high temperature oxidation of mechanical alloyed Fe-Al coating

    NASA Astrophysics Data System (ADS)

    Aryanto, Didik; Sudiro, Toto; Wismogroho, Agus S.

    2016-04-01

    The structure and high temperature oxidation resistance of Fe-Al coating on low carbon steel were investigated. The Fe-Al coating was deposited on the surface of low carbon steel using a mechanical alloying method. The coating was then annealed at 600°C for 2 hour in a vacuum of 5 Pa. The cyclic-oxidation tests of low carbon steel, Fe-Al coatings with and without annealing were performed at 600°C for up to 60h in air. The structure of oxidized samples was studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy X-ray spectroscopy (EDS). The results show that the Fe-Al coatings exhibit high oxidation resistance compared to the uncoated steel. After 60 h exposure, the uncoated steel formed mainly Fe3O4 and Fe2O3 layers with the total thickness of around 75.93 µm. Fe-Al coating without annealing formed a thin oxide layer, probably (Fe,Al)2O3. Meanwhile, for annealed sample, EDX analysis observed the formation of two Fe-Al layers with difference in elements concentration. The obtained results suggest that the deposition of Fe-Al coating on low carbon steel can improve the oxidation resistance of low carbon steel.

  14. Deposition and Characterization of Al:ZnO Thin Films for Optoelectronic Applications

    NASA Astrophysics Data System (ADS)

    Pandey, R. K.; Mishra, Swati; Bajpai, P. K.

    2016-07-01

    Transparent aluminum-doped zinc oxide (Al:ZnO) thin films have been successfully synthesized on silicon substrates at room temperature using a sol-gel spin-coating method. The structural and optical properties and surface morphology of the synthesized films were characterized using x-ray diffraction (XRD) analysis, ultraviolet-visible (UV-Vis) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, micro-Raman spectroscopy, and atomic force microscopy (AFM). The prepared Al:ZnO retained the hexagonal wurtzite structure of ZnO. FTIR and Raman spectra clearly revealed a major peak at 437 cm-1, associated with the ZnO bond. UV-Vis spectra showed that the Al:ZnO films were transparent from the near-ultraviolet to near-infrared region. The effect of film thickness on the physical and optical properties of the Al:ZnO thin films for 2.0 at.% aluminum concentration was investigated. Measurements revealed that the film transparency, optical energy bandgap, Urbach energy, extinction coefficient, and porosity varied with the film thickness. The energy bandgap values for the prepared thin films increased in the range of 3.18 eV to 3.2 eV with increasing film thickness.

  15. Precipitation of ZnO in Al 2O 3-doped zinc borate glass ceramics

    NASA Astrophysics Data System (ADS)

    Masai, Hirokazu; Ueno, Takahiro; Takahashi, Yoshihiro; Fujiwara, Takumi

    2011-10-01

    Crystallization behavior of the oxide semiconductor ZnO in zinc borate glass was investigated. The precipitated crystalline phase of glass ceramics containing a small amount of Al 2O 3 was α-Zn 3B 2O 6 whereas that of the glass ceramics containing a large amount of Al 2O 3 was ZnO. It was found that the c-oriented precipitation of ZnO in a glass ceramic was brought about by the in-plane crystal growth of needle-like ZnO crystallites along the a-axis. Amount of Al 2O 3 that can make glass network affected the coordination state of B 2O 3 in the glass, and a three-coordinated BO 3 unit was preferentially formed in the glass containing a higher amount of Al 2O 3. The present results suggest that crystallization of ZnO from multi-component glass is dominated by the local coordination state of the mother glass.

  16. Microstructural evolution in Al-Zn-Mg-Cu-Sc-Zr alloys during short-time homogenization

    NASA Astrophysics Data System (ADS)

    Liu, Tao; He, Chun-nian; Li, Gen; Meng, Xin; Shi, Chun-sheng; Zhao, Nai-qin

    2015-05-01

    Microstructural evolution in a new kind of aluminum (Al) alloy with the chemical composition of Al-8.82Zn-2.08Mg-0.80Cu-0.31Sc-0.3Zr was investigated. It is found that the secondary phase MgZn2 is completely dissolved into the matrix during a short homogenization treatment (470°C, 1 h), while the primary phase Al3(Sc,Zr) remains stable. This is due to Sc and Zr additions into the Al alloy, high Zn/Mg mass ratio, and low Cu content. The experimental findings fit well with the results calculated by the homogenization diffusion kinetics equation. The alloy shows an excellent mechanical performance after the short homogenization process followed by hot-extrusion and T6 treatment. Consequently, a good combination of low energy consumption and favorable mechanical properties is obtained.

  17. Inhibition of trace element release during Fe(II)-activated recrystallization of Al-, Cr-, and Sn-substituted goethite and hematite

    SciTech Connect

    Frierdich, Andrew J.; Scherer, M.; Bachman, Jonathan E.; Engelhard, Mark H.; Rapponotti, Brett W.; Catalano, Jeffrey G.

    2012-09-18

    Aqueous Fe(II) reacts with Fe(III) oxides by coupled electron transfer and atom exchange (ETAE) resulting in mineral recrystallization, contaminant reduction, and trace element cycling. Previous studies of Fe(II)-Fe(III) ETAE have explored the reactivity of either pure iron oxide phases or those containing small quantities of soluble trace elements. Naturally occurring iron oxides, however, contain substantial quantities of insoluble impurities (e.g., Al) which are known to affect the chemical properties of such minerals. Here we explore the effect of Al(III), Cr(III), and Sn(IV) substitution on trace element release from Ni(II)-substituted goethite and Zn(II)-substituted hematite during reaction with aqueous Fe(II). Fe(II)-activated trace element release is substantially inhibited from both minerals when an insoluble element is co-substituted into the structure, and the total amount of release decreases exponentially with increasing co substituent. The limited changes in surface composition that occur following reaction with Fe(II) indicate that Al, Cr, and Sn do not exsolve from the structure and that Ni and Zn released to solution originate primarily from the bulk rather than the particle exterior (upper ~3 nm). Incorporation of Al into goethite substantially decreases the amount of iron atom exchange with aqueous Fe(II) and, consequently, the amount of Ni release from the structure. This implies that trace element release inhibition caused by substituting insoluble elements results from a decrease in the amount of mineral recrystallization. These results suggest that naturally occurring iron oxides containing insoluble elements are less susceptible to Fe(II)-activated recrystallization and exhibit a greater retention of trace elements and contaminants than pure mineral phases.

  18. Inhibition of trace element release during Fe(II)-activated recrystallization of Al-, Cr-, and Sn-substituted goethite and hematite.

    PubMed

    Frierdich, Andrew J; Scherer, Michelle M; Bachman, Jonathan E; Engelhard, Mark H; Rapponotti, Brett W; Catalano, Jeffrey G

    2012-09-18

    Aqueous Fe(II) reacts with Fe(III) oxides by coupled electron transfer and atom exchange (ETAE) resulting in mineral recrystallization, contaminant reduction, and trace element cycling. Previous studies of Fe(II)-Fe(III) ETAE have explored the reactivity of either pure iron oxide phases or those containing small quantities of soluble trace elements. Naturally occurring iron oxides, however, contain substantial quantities of insoluble impurities (e.g., Al) which are known to affect the chemical properties of such minerals. Here we explore the effect of Al(III), Cr(III), and Sn(IV) substitution (1-8 mol %) on trace element release from Ni(II)-substituted goethite and Zn(II)-substituted hematite during reaction with aqueous Fe(II). Fe(II)-activated trace element release is substantially inhibited from both minerals when an insoluble element is cosubstituted into the structure, and the total amount of release decreases exponentially with increasing cosubstituent. The limited changes in surface composition that occur following reaction with Fe(II) indicate that Al, Cr, and Sn do not exsolve from the structure and that Ni and Zn released to solution originate primarily from the bulk rather than the particle exterior (upper ~3 nm). Incorporation of Al into goethite substantially decreases the amount of iron atom exchange with aqueous Fe(II) and, consequently, the amount of Ni release from the structure. This implies that trace element release inhibition caused by substituting insoluble elements results from a decrease in the amount of mineral recrystallization. These results suggest that naturally occurring iron oxides containing insoluble elements are less susceptible to Fe(II)-activated recrystallization and exhibit a greater retention of trace elements and contaminants than pure mineral phases. PMID:22924460

  19. Nanostructure evolution in joining of Al and Fe nanoparticles with femtosecond laser irradiation

    SciTech Connect

    Jiao, Z.; Huang, H.; Zhou, Y. E-mail: nzhou@uwaterloo.ca; Liu, L.; Hu, A.; Duley, W.; He, P. E-mail: nzhou@uwaterloo.ca

    2014-04-07

    The joining of Al-Fe nanoparticles (NPs) by femtosecond (fs) laser irradiation is reported in this paper. Fe and Al NPs were deposited on a carbon film in vacuum via fs laser ablation. Particles were then exposed to multiple fs laser pulses at fluences between 0.5 and 1.3 mJ/cm{sup 2}. Transmission Electron Microscopy (TEM) and Electron Diffraction X-ray observations indicate that Al and Fe NPs bond to each other under these conditions. For comparison, bonding of Al to Al and Fe to Fe NPs was also investigated. The nanostructure, as observed using TEM, showed that individual Al NPs were monocrystalline while individual Fe NPs were polycrystalline prior to joining and that these structures are retained after the formation of Al-Al and Fe-Fe NPs. Al-Fe NPs produced by fs laser joining exhibited a mixed amorphous and crystalline phase at the interface. Bonding is suggested to originate from intermixing within a region of high field intensity between particles.

  20. 840 mW continuous-wave Fe:ZnSe laser operating at 4140 nm.

    PubMed

    Evans, Jonathan W; Berry, Patrick A; Schepler, Kenneth L

    2012-12-01

    We report the demonstration of high-power (840 mW) continuous-wave laser oscillation from Fe2+ ions in zinc selenide. The output spectrum of the Fe:ZnSe laser had a line-center near 4140 nm with a linewidth of 80 nm. The beam quality was measured to be M2≤1.2 with a maximum slope efficiency of 47%. Small shifts observed in output wavelength with increased output power were attributed to thermal effects. No thermal roll-off of slope efficiency was observed at the maximum of output power. PMID:23330210

  1. Characterization of Co2FeAl nanowires

    NASA Astrophysics Data System (ADS)

    Sapkota, Keshab R.; Pegg, I. L.; Philip, J.

    2011-03-01

    Heusler alloy, Co 2 FeAl (CFA) is a potentially useful material in the field of spintronics due to its high spin polarization. The CFA nanowires are grown for the first time by the electrospinning method. The diameters of the wires formed are ranging from 80 -- 100 nm. The structural characterization of the nanowires is done using X-Ray diffraction and Raman spectroscopy. The nanowires exhibit cubic structure with a lattice constant, a = 2.44 Å. Parallel arrays of nanowires are grown for magnetic characterization using electric field applied at the collector plate. The nanowires exhibit ferromagnetic behavior with a Curie temperature higher than 400 K. Nanoscale devices are fabricated with single CFA nanowire to understand the magnetotransport properties. This work has been supported by funding from NSF under CAREER Grant No. ECCS-0845501 and NSF-MRI, DMR-0922997.

  2. Concentric nano rings observed on Al-Cu-Fe microspheres

    NASA Astrophysics Data System (ADS)

    Li, Chunfei; Wang, Limin; Hampikian, Helen; Bair, Matthew; Baker, Andrew; Hua, Mingjian; Wang, Qiongshu; Li, Dingqiang

    2016-05-01

    It is well known that when particle size is reduced, surface effect becomes important. As a result, micro/nanoparticles tend to have well defined geometric shapes to reduce total surface energy, as opposed to the irregular shapes observed in most bulk materials. The surface of such micro/nanostructures are smooth. Any deviation from a smooth surface implies an increased surface energy which is not energetically favorable. Here, we report an observation of spherical particles in an alloy of Al65Cu20Fe15 nominal composition prepared by arc melting. Such spherical particles stand out from those reported so far due to the decoration of concentric nanorings on the surface. Three models for the formation of these concentric ring patterns are suggested. The most prominent ones assume that the rings are frozen features of liquid motion which could open the door to investigate the kinetics of liquid motion on the micro/nanometer scale.

  3. Fe{sup 2+} : ZnSe laser pumped by a nonchain electric-discharge HF laser at room temperature

    SciTech Connect

    Velikanov, S D; Zakharov, N G; Shchurov, V V; Danilov, V P; Il'ichev, N N; Kazantsev, S Yu; Kalinushkin, V P; Kononov, I G; Studenikin, M I; Pashinin, P P; Firsov, K N; Nasibov, A S; Shapkin, P V

    2014-02-28

    The characteristics of a Fe{sup 2+} : ZnSe laser in a scheme with transverse pumping by a nonchain electric-discharge HF laser at room temperature are studied. Doping of ZnSe crystals with Fe{sup 2+} ions was performed by diffusion simultaneously through two surfaces under the conditions of thermodynamic equilibrium. It is found that the Fe{sup 2+} : ZnSe laser pulses are modulated by short spikes (3 – 7 ns at half maximum at low pump energies), whose number decreases and modulation depth increases as the pump energy decreases to a threshold value. A laser pulse energy of 30.6 mJ is achieved at a pulse duration at half maximum of ∼125 ns (at high pump energies); the possibility of a further increase in the energy of Fe{sup 2+} : ZnSe lasers pumped by nonchain HF lasers is discussed. (lasers)

  4. Effect of thermal annealing on the structure of ZnSe/Al2O3 nanocomposite films

    NASA Astrophysics Data System (ADS)

    Dedyukhin, A. A.; Krylov, P. N.; Kostenkov, N. V.; Zakirova, R. M.; Fedotova, I. V.

    2016-04-01

    The ZnSe/Al2O3 nanocomposite films synthesized by laser evaporation followed by heat treatment are studied. X-ray diffraction and electron-microscopic investigations of the as-deposited films demonstrate the presence of ZnSe crystallites in an Al2O3 amorphous matrix. Annealing changes the structures of ZnSe and Al2O3, increases the ZnSe crystallite size, and causes the appearance of the ZnSeO4 phase. The presence of aluminum oxide layers decreases the phase transformation temperature of zinc selenide.

  5. Abnormal variation of band gap in Zn doped Bi{sub 0.9}La{sub 0.1}FeO{sub 3} nanoparticles: Role of Fe-O-Fe bond angle and Fe-O bond anisotropy

    SciTech Connect

    Xu, Xunling; Liu, Weifang E-mail: shouyu.wang@yahoo.com; Wu, Ping; Zhang, Hong; Guo, Minchen; Han, Yuling; Zhang, Chuang; Gao, Ju; Rao, Guanghui; Wang, Shouyu E-mail: shouyu.wang@yahoo.com

    2015-07-27

    Bi{sub 0.9}La{sub 0.1}FeO{sub 3} (BLFO) and Bi{sub 0.9}La{sub 0.1}Fe{sub 0.99}Zn{sub 0.01}O{sub 3} (BLFZO) nanoparticles were prepared via a sol-gel method. The oxygen vacancies and holes increase with Zn doping analyzed through X-ray photoelectron spectroscopy, which could contribute to the increase of leakage current density. However, with the increase of the defects (oxygen vacancies and holes), the band gap of BLFZO also is increased. To explain the abnormal phenomenon, the bandwidth of occupied and unoccupied bands was analyzed based on the structural symmetry driven by the Fe-O-Fe bond angle and Fe-O bond anisotropy.

  6. Structural, magnetic and dielectric properties of NiZnFe2O4 nanocrystals

    NASA Astrophysics Data System (ADS)

    Datt, Gopal; Abhyankar, A. C.

    2016-04-01

    In this paper we report the structural, magnetic and dielectric properties of hydrothermally synthesised NiZnFe2O4 nanocrystals. The Rietveld refinement of XRD data reveals that nanoparticles are crystallized in spinel structure with Fd-3m space group and the lattice parameter is found to be 8.413 (2) Ȧ. The FESEM microstructures reveal that the particles are in the spherical shape with a size lying between 20-25 nm. The magnetic data analysis shows that the coercivity of the nanoparticles is almost zero at room temperature and the magnetization value is Ms = 45 emu/g. The dielectric relaxation of the NiZnFe2O4 nanocrystals obeys the modified Debye model which considers the more than one ion contributing to the relaxation. The ac-conductivity of these nanocrystals is governed by the universal dielectric response (UDR) model, where the variable-range hopping of localized polarons is responsible for conduction.

  7. Enhancement of photoluminescence properties in ZnO/AlN bilayer heterostructures grown by atomic layer deposition

    SciTech Connect

    Zhu, Shang-Bin; Lu, Hong-Liang Zhang, Yuan; Sun, Qing-Qing; Zhou, Peng; Ding, Shi-Jin; Zhang, David Wei; Zhang, Qiu-Xiang

    2015-01-15

    The AlN/ZnO bilayer heterostructures were deposited on Si (100) substrate by thermal atomic layer deposition. X-ray diffraction results show that the crystallinity of polycrystalline ZnO layer is enhanced by amorphous AlN capping layer. Compared with ZnO thin film, ZnO/AlN bilayer with 10.7 nm AlN capping layer exhibits three times enhanced near band edge (NBE) emission from the photoluminescence measurements. In addition, the near band edge emission from the ZnO can be further increased by ∼10 times through rapid thermal annealing at 600 °C. The underlying mechanisms for the enhancement of the NBE emission after coating AlN capping layer and thermal treatment are discussed. These results suggest that coating of a thin AlN layer and sequential thermal treatments can effectively tailor the luminescence properties of ZnO film.

  8. Interdiffusion and impurity diffusion in polycrystalline Mg solid solution with Al or Zn

    SciTech Connect

    Kammerer, Catherine; Kulkarni, Nagraj S; Warmack, Robert J Bruce; Sohn, Yong Ho

    2014-01-01

    Interdiffusion and impurity diffusion in Mg binary solid solutions, Mg(Al) and Mg(Zn) were investigated at temperatures ranging from 623 to 723 K. Interdiffusion coef cients were determined via the Boltzmann Matano Method using solid-to-solid diffusion couples assembled with polycrystalline Mg and Mg(Al) or Mg(Zn) solid solutions. In addition, the Hall method was employed to extrapolate the impurity diffusion coef cients of Al and Zn in pure polycrystalline Mg. For all diffusion couples, electron micro-probe analysis was utilized for the measurement of concentration pro les. The interdiffusion coef cient in Mg(Zn) was higher than that of Mg(Al) by an order of magnitude. Additionally, the interdiffusion coef cient increased signi cantly as a function of Al content in Mg(Al) solid solution, but very little with Zn content in Mg(Zn) solid solution. The activation energy and pre-exponential factor for the average effective interdiffusion coef cient in Mg(Al) solid solution were determined to be 186.8 ( 0.9) kJ/mol and 7.69 x 10-1 ( 1.80 x 10-1) m2/s, respectively, while those determined for Mg(Zn) solid solution were 139.5 ( 4.0) kJ/mol and 1.48 x 10-3 ( 1.13 x 10-3) m2/s. In Mg, the Zn impurity diffusion coef cient was an order of magnitude higher than the Al impurity diffusion coef cient. The activation energy and pre-exponential factor for diffusion of Al impurity in Mg were determined to be 139.3 ( 14.8) kJ/mol and 6.25 x 10-5 ( 5.37 x 10-4) m2/s, respectively, while those for diffusion of Zn impurity in Mg were determined to be 118.6 ( 6.3) kJ/mol and 2.90 x 10-5 ( 4.41 x 10-5) m2/s.

  9. Encapsulation of Ni0.8Zn0.2Fe2O4 single crystals in multiwall carbon nanotubes.

    PubMed

    Yahya, Noorhana; Akhtar, Majid Niaz; Koziol, Krzysztof

    2012-10-01

    Magnetic nanoparticles in the hollow region of carbon nanotubes have attraction due to their changing physical electrical and magnetic properties. Nickel zinc ferrite plays an important role in many applications due to its superior magnetic properties. Ni0.8Zn0.2Fe2O4 single crystals were encapsulated in multiwall carbon nanotubes (MWCNTs). The magnetic nano crystals were prepared using a sol-gel self combustion method at the sintering temperature of 750 degrees C and were characterized by XRD, FESEM, TEM and VSM. Initial permeability, Q-factor and relative loss factor were measured by impedance vector network analyzer. XRD patterns were used for the phase identification. FESEM images show morphology and dimensions of the grains of Ni0.8Zn0.2Fe2O4 single crystals and Ni0.8Zn0.2Fe2O4 single crystals in MWCNTs. TEM images were used to investigate single crystal and encapsulation of Ni0.8Zn0.2Fe2O4 single crystals in the MWCNTs. VSM results confirmed super paramagnetic behaviour of encapsulated Ni0.8Zn0.2Fe2O4 single crystals. It was also attributed that encapsulated Ni0.8Zn0.2Fe2O4 single crystals in MWCNTs showed a higher initial permeability (51.608), Q-factor (67.069), and low loss factor (0.0002) as compared to Ni0.8Zn0.2Fe2O4 single crystals. The new encapsulated Ni0.8Zn0.2Fe2O4 single crystals in the MWCNTs may have potential applications in electronic and medical industries. PMID:23421187

  10. ZnFe2O4 nanoparticles as radiosensitizers in radiotherapy of human prostate cancer cells.

    PubMed

    Meidanchi, Alireza; Akhavan, Omid; Khoei, Samideh; Shokri, Ali A; Hajikarimi, Zahra; Khansari, Nakisa

    2015-01-01

    Nanoparticles of high-Z elements exhibit stronger photoelectric effects than soft tissues under gamma irradiation. Hence, they can be used as effective radiosensitizers for increasing the efficiency of current radiotherapy. In this work, superparamagnetic zinc ferrite spinel (ZnFe2O4) nanoparticles were synthesized by a hydrothermal reaction method and used as radiosensitizers in cancer therapy. The magnetic nanoparticles showed fast separation from solutions (e.g., ~1 min for 2 mg mL(-1) of the nanoparticles in ethanol) by applying an external magnetic field (~1T). The ZnFe2O4 nanoparticles were applied in an in vitro radiotherapy of lymph node carcinoma of prostate cells (as high radioresistant cells) under gamma irradiation of (60)Co source. The nanoparticles exhibited no significant effects on the cancer cells up to the high concentration of 100 μg mL(-1), in the absence of gamma irradiation. The gamma irradiation alone (2Gy dose) also showed no significant effects on the cells. However, gamma irradiation in the presence of 100 μg mL(-1) ZnFe2O4 nanoparticles resulted in ~53% inactivation of the cells (~17 times higher than the inactivation that occurred under gamma irradiation alone) after 24h. The higher cell inactivation was assigned to interaction of gamma radiation with nanoparticles (photoelectric effect), resulting in a high level electron release in the media of the radioresistant cells. Our results indicated that ZnFe2O4 nanoparticles not only can be applied in increasing the efficiency of radiotherapy, but also can be easily separated from the cell environment by using an external magnetic field after the radiotherapy. PMID:25492003

  11. Room-temperature high-energy Fe{sup 2+}:ZnSe laser

    SciTech Connect

    Gavrishchuk, E M; Rodin, S A; Kazantsev, S Yu; Kononov, I G; Firsov, K N

    2014-06-30

    The characteristics of a room-temperature laser based on a polycrystalline Fe{sup 2+}:ZnSe sample pumped by a non-chain HF laser are studied. The laser energy is E=175 mJ at the efficiencies with respect to the incident and absorbed pump energy η{sub p} ≈ 22% and h{sub abs} ≈ 29%, respectively. (letters)

  12. Transformation of polymetallic dust in the organic horizon of Al-Fe-humus podzol (field experiment)

    NASA Astrophysics Data System (ADS)

    Lyanguzova, I. V.; Goldvirt, D. K.; Fadeeva, I. K.

    2015-07-01

    Scanning electron microscopy with an X-ray spectral microanalysis showed that the ash matter from the organic horizons (after ignition) of control and experimental plots mainly (>85%) consists of different soil-forming minerals and iron oxides (particularly magnetite). From 10% to 15% of particles in the organic horizon of Al-Fe-humus podzol (Albic Rustic Podzol) of the experimental plot were represented by polymetallic ball-shaped dust particles that were preserved in the soil without significant transformation for 14 years after their artificial application. The total contents of Cu, Pb, As, and Ni in the organic horizon on the experimental plot were 22-100 times higher than those in the control; the contents of Zn and Fe were 2-5 times higher. The sequence of chemical elements according to their total contents in the samples of control and experimental plots was different. The portion of available forms of heavy metal (Ni, Cu, and Co) compounds extractable with 1.0 M HCl averaged 20-30% of their total contents in the soil. More than 80% of acid-soluble forms of heavy metals were concentrated in the organic horizon of contaminated podzol soil, which represents the biogeochemical barrier to the migration of pollutants down the soil profile. Durable fixation of heavy metals in the organic horizon and their weak migration into the mineral soil layers significantly hamper the processes of self-purification of contaminated soils.

  13. Combustion synthesized copper-ion substituted FeAl2O4 (Cu0.1Fe0.9Al2O4): A superior catalyst for methanol steam reforming compared to its impregnated analogue

    NASA Astrophysics Data System (ADS)

    Maiti, Sayantani; Llorca, Jordi; Dominguez, Montserrat; Colussi, Sara; Trovarelli, Alessandro; Priolkar, Kaustubh R.; Aquilanti, Giuliana; Gayen, Arup

    2016-02-01

    A series of copper ion substituted MAl2O4 (M = Mg, Mn, Fe and Zn) spinels is prepared by a single step solution combustion synthesis (SCS) and tested for methanol steam reforming (MSR). The copper ion substituted Cu0.1Fe0.9Al2O4 appears to be the most active, showing ∼98% methanol conversion at 300 °C with ∼5% CO selectivity at GHSV = 30,000 h-1 and H2O:CH3OH = 1.1. The analogous impregnated catalyst, CuO (10 at%)/FeAl2O4, is found to be much less active. These materials are characterized by XRD, H2-TPR, BET, HRTEM, XPS and XANES analyses. Spinel phase formation is highly facilitated upon Cu-ion substitution and Cu loading beyond 10 at% leads to the formation of CuO as an additional phase. The ionic substitution of copper in FeAl2O4 leads to the highly crystalline SCS catalyst containing Cu2+ ion sites that are shown to be more active than the dispersed CuO nano-crystallites on the FeAl2O4 impregnated catalyst, despite its lower surface area. The as prepared SCS catalyst contains also a portion of copper as Cu1+ that increases when subjected to reforming atmosphere. The MSR activity of the SCS catalyst decreases with time-on-stream due to the sintering of catalyst crystallites as established from XPS and HRTEM analyses.

  14. Structural Investigation of the (010) Surface of the Al13Fe4 Catalyst

    NASA Astrophysics Data System (ADS)

    Ledieu, J.; Gaudry, É.; Loli, L. N. Serkovic; Villaseca, S. Alarcón; de Weerd, M.-C.; Hahne, M.; Gille, P.; Grin, Y.; Dubois, J.-M.; Fournée, V.

    2013-02-01

    We have investigated the structure of the Al13Fe4(010) surface using both experimental and ab initio computational methods. The results indicate that the topmost surface layers correspond to incomplete puckered (P) planes present in the bulk crystal structure. The main building block of the corrugated termination consists of two adjacent pentagons of Al atoms, each centered by a protruding Fe atom. These motifs are interconnected via additional Al atoms referred to as “glue” atoms which partially desorb above 873 K. The surface structure of lower atomic density compared to the bulk P plane is explained by a strong Fe-Al-Fe covalent polar interaction that preserves intact clusters at the surface. The proposed surface model with identified Fe-containing atomic ensembles could explain the Al13Fe4 catalytic properties recently reported in line with the site-isolation concept [M. Armbrüster , Nat. Mater. 11, 690 (2012)NMAACR1476-1122].

  15. Assessment of retrogression and re-aging treatment on microstructural and mechanical properties of Al-Zn-Mg-Cu P/M alloy

    SciTech Connect

    Naeem, Haider T.; Mohammad, Kahtan S.; Hussin, Kamarudin; Tan, T. Qing; Idris, M. Sobri

    2015-05-15

    In order to understand the importance of the retrogression and re-aging as a heat treatment for improving microstructural and mechanical properties of the Al-Zn-Mg-Cu powder metallurgy alloys, Al-Zn-Mg-Cu-Fe-Cr alloys were fabricated from the elemental powders. Green compacts are compressed under compaction pressure about 370 MPa. The sintering process carried out for the samples of aluminum alloys at temperature was 650°C under argon atmosphere for two hours. The sintered compacts were subjected into homogenizing condition at 470°C for 1.5 hours and then aged at 120°C for 24 hours (T6 temper) after that it carried out the retrogressed at 180°C for 30 min., and then re-aged at 120°C for 24 hours (RRA). Observations microstructures were examined using optical, scanning electron microscopy coupled with energy dispersive spectroscopy and X-ray diffraction. Density and porosity content was conducted for the samples of alloys. The result showing that the highest Vickers hardness exhibited for an Al-Zn-Mg-Cu alloy after underwent the retrogression and reaging treatment. Increasing in hardness was because of the precipitation hardening through precipitate the (Mg Zn) and (Mg{sub 2}Zn{sub 11}) phases during matrix of aluminum-alloy.

  16. Assessment of retrogression and re-aging treatment on microstructural and mechanical properties of Al-Zn-Mg-Cu P/M alloy

    NASA Astrophysics Data System (ADS)

    Naeem, Haider T.; Mohammad, Kahtan S.; Hussin, Kamarudin; Tan, T. Qing; Idris, M. Sobri

    2015-05-01

    In order to understand the importance of the retrogression and re-aging as a heat treatment for improving microstructural and mechanical properties of the Al-Zn-Mg-Cu powder metallurgy alloys, Al-Zn-Mg-Cu-Fe-Cr alloys were fabricated from the elemental powders. Green compacts are compressed under compaction pressure about 370 MPa. The sintering process carried out for the samples of aluminum alloys at temperature was 650°C under argon atmosphere for two hours. The sintered compacts were subjected into homogenizing condition at 470°C for 1.5 hours and then aged at 120°C for 24 hours (T6 temper) after that it carried out the retrogressed at 180°C for 30 min., and then re-aged at 120°C for 24 hours (RRA). Observations microstructures were examined using optical, scanning electron microscopy coupled with energy dispersive spectroscopy and X-ray diffraction. Density and porosity content was conducted for the samples of alloys. The result showing that the highest Vickers hardness exhibited for an Al-Zn-Mg-Cu alloy after underwent the retrogression and reaging treatment. Increasing in hardness was because of the precipitation hardening through precipitate the (Mg Zn) and (Mg2Zn11) phases during matrix of aluminum-alloy.

  17. Corrosion Protection of Al/Au/ZnO Anode for Hybrid Cell Application.

    PubMed

    Slaughter, Gymama; Stevens, Brian

    2015-01-01

    Effective protection of power sources from corrosion is critical in the development of abiotic fuel cells, biofuel cells, hybrid cells and biobateries for implantable bioelectronics. Corrosion of these bioelectronic devices result in device inability to generate bioelectricity. In this paper Al/Au/ZnO was considered as a possible anodic substrate for the development of a hybrid cell. The protective abilities of corrosive resistant aluminum hydroxide and zinc phosphite composite films formed on the surface of Al/Au/ZnO anode in various electrolyte environments were examined by electrochemical methods. The presence of phosphate buffer and physiological saline (NaCl) buffer allows for the formation of aluminum hyrdroxide and zinc phosphite composite films on the surface of the Al/Au/ZnO anode that prevent further corrosion of the anode. The highly protective films formed on the Al/Au/ZnO anode during energy harvesting in a physiological saline environment resulted in 98.5% corrosion protective efficiency, thereby demonstrating that the formation of aluminum hydroxide and zinc phosphite composite films are effective in the prevention of anode corrosion during energy harvesting. A cell assembly consisting of the Al/Au/ZnO anode and platinum cathode resulted in an open circuit voltage of 1.03 V. A maximum power density of 955.3 mW/ cm² in physiological saline buffer at a cell voltage and current density of 345 mV and 2.89 mA/ cm², respectively. PMID:26580661

  18. Preparation, characterization and dye adsorption of Au nanoparticles/ZnAl layered double oxides nanocomposites

    NASA Astrophysics Data System (ADS)

    Zhang, Yu Xin; Hao, Xiao Dong; Kuang, Min; Zhao, Han; Wen, Zhong Quan

    2013-10-01

    In this work, Au/ZnAl-layer double oxides (LDO) nanocomposties were prepared through a facile calcination process of AuCl4- intercalated ZnAl-layered double hydroxides (LDHs) nanocomposites. The morphology and crystal structure of these nanocomposites were characterized by Scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and N2 sorption analysis. By tailoring the process parameter, such as calcination temperature, heating time and the component composition, the adsorption properties of methyl orange (MO) on the Au/ZnAl-LDO nanocomposites were investigated in this work. In a typical adsorption process, it was found that 0.985 mg of MO (0.01 g L-1, 100 mL, 1 mg of MO in total) can be removed in 60 min by utilizing only 2.5 mg of Au/ZnAl-LDO (Au content, 1%) as adsorbents. Our adsorption data obtained from the Langmuir model also gave good values of the determination coefficient, and the saturated adsorption capacity of Au/ZnAl-LDO nanocomposites for MO was found to be 627.51 mg/g under ambient condition (e.g., room temperature, 1 atm). In principle, these hybrid nanostructures with higher adsorption abilities could be very promising adsorbents for wastewater treatment.

  19. Corrosion Protection of Al/Au/ZnO Anode for Hybrid Cell Application

    PubMed Central

    Slaughter, Gymama; Stevens, Brian

    2015-01-01

    Effective protection of power sources from corrosion is critical in the development of abiotic fuel cells, biofuel cells, hybrid cells and biobateries for implantable bioelectronics. Corrosion of these bioelectronic devices result in device inability to generate bioelectricity. In this paper Al/Au/ZnO was considered as a possible anodic substrate for the development of a hybrid cell. The protective abilities of corrosive resistant aluminum hydroxide and zinc phosphite composite films formed on the surface of Al/Au/ZnO anode in various electrolyte environments were examined by electrochemical methods. The presence of phosphate buffer and physiological saline (NaCl) buffer allows for the formation of aluminum hyrdroxide and zinc phosphite composite films on the surface of the Al/Au/ZnO anode that prevent further corrosion of the anode. The highly protective films formed on the Al/Au/ZnO anode during energy harvesting in a physiological saline environment resulted in 98.5% corrosion protective efficiency, thereby demonstrating that the formation of aluminum hydroxide and zinc phosphite composite films are effective in the prevention of anode corrosion during energy harvesting. A cell assembly consisting of the Al/Au/ZnO anode and platinum cathode resulted in an open circuit voltage of 1.03 V. A maximum power density of 955.3 μW/ cm2 in physiological saline buffer at a cell voltage and current density of 345 mV and 2.89 mA/ cm2, respectively. PMID:26580661

  20. Estimated daily intake of Fe, Cu, Ca and Zn through common cereals in Tehran, Iran.

    PubMed

    Kashian, S; Fathivand, A A

    2015-06-01

    This paper presents the findings of study undertaken to estimate the dietary intake of iron (Fe), copper (Cu), calcium (Ca) and zinc (Zn) through common cereals in Tehran, Iran. 100 samples of rice, wheat and barley were collected from various brands between August and October 2013. The samples were analyzed performing instrumental neutron activation analysis (INAA). The dietary intake for adults was estimated by a total cereal study. Calculations were carried out on the basis of the reported adults' average food consumption rate data. The total daily intake estimated in mgd(-1) for Tehran population were 3.6 (Fe), 10.2 (Zn), 0.3 (Cu) and 234.5 (Ca). Wheat showed the highest contribution to Zn, Cu and Ca intakes. Furthermore, intakes were compared with recommended dietary allowance (RDA). Zn total intake (10.2mgd(-1)) was comparable with RDA values for males (11mgd(-1)) and was higher than recommended value for females (8mgd(-1)). The intakes of other studied elements were below the respective RDAs. PMID:25624223

  1. Synthesis and characterization of core@shell (ZnO@γ-Fe2O3) structured nanoparticles with two morphologies

    NASA Astrophysics Data System (ADS)

    Balti, Imen; Smiri, Laila Samia; Rabu, Pierre; Léone, Philippe; Gautron, Eric; Viana, Bruno; Jouini, Noureddine

    2013-03-01

    Core-shell ZnO/γ-Fe2O3 nanoparticles were prepared via a simple method using forced hydrolysis of acetate metallic salts in a polyol medium. Two types of morphologies can be easily obtained: (i) quasi-spherical ZnO core 20 nm in diameter coated with a continuous shell with 3 nm in length, (ii) rod-like ZnO decorated with γ-Fe2O3 nanoparticles. The ZnO nanorods are 80 nm in diameter and 400 nm in length. The maghemite (γ-Fe2O3) nanoparticles with 5 nm in diameter are strongly bonded to ZnO, well separated from each other and form a monolayer on the surface of ZnO nanorods. In both systems, coating ZnO by γ-Fe2O3 inhibits the surface defects and thus enhances the UV luminescence. The two systems present a superparamagnetic behavior with blocking temperature depending on the morphology: the decorated ZnO nanorods present a blocking temperature around 6 K whereas this temperature is significantly higher (300 K) for spherical core-shell nanoparticles.

  2. Investigation of Fe:ZnSe laser in pulsed and repetitively pulsed regimes

    SciTech Connect

    Velikanov, S D; Zaretskiy, N A; Zotov, E A; Maneshkin, A A; Chuvatkin, R S; Yutkin, I M; Kozlovsky, V I; Korostelin, Yu V; Krokhin, O N; Podmar'kov, Yu P; Savinova, S A; Skasyrsky, Ya K; Frolov, M P

    2015-01-31

    The characteristics of a Fe:ZnSe laser pumped by a single-pulse free-running Er : YAG laser and a repetitively pulsed HF laser are presented. An output energy of 4.9 J is achieved in the case of liquid-nitrogen cooling of the Fe{sup 2+}:ZnSe active laser element longitudinally pumped by an Er:YAG laser with a pulse duration of 1 ms and an energy up to 15 J. The laser efficiency with respect to the absorbed energy is 47%. The output pulse energy at room temperature is 53 mJ. The decrease in the output energy is explained by a strong temperature dependence of the upper laser level lifetime and by pulsed heating of the active element. The temperature dependence of the upper laser level lifetime is used to determine the pump parameters needed to achieve high pulse energies at room temperature. Stable repetitively-pulsed operation of the Fe{sup 2+}:ZnSe laser at room temperature with an average power of 2.4 W and a maximum pulse energy of 14 mJ is achieved upon pumping by a 1-s train of 100-ns HF laser pulses with a repetition rate of 200 Hz. (lasers)

  3. Fe-Zn Alloy Coating on Galvannealed (GA) Steel Sheet to Improve Product Qualities

    NASA Astrophysics Data System (ADS)

    Pradhan, Debabrata; Guin, Akshya Kumar; Raju, Pankaj; Manna, Manindra; Dutta, Monojit; Venugopalan, T.

    2014-09-01

    Galvannealed steel sheets (GA) have become the mainstream steel sheet for automobile applications because of their superior corrosion resistance, paintability, and weldability. To impart specific properties, different coatings on GA steel sheet were reported to improve properties further. In this context, we have developed an electroplating process (flash coating) for bright and adherent Fe-Zn alloy coating on GA steel sheet to enhance performances such as weldability, frictional behavior, phosphatability, and defect coverage. A comparative study with bare GA steel sheet was carried out for better elastration. The electroplating time was reduced below 10 s for practical applicability in an industrial coating line by modulating the bath composition. Electroplating was performed at current density of 200-500 A/m2 which yielded with higher cathode current efficiency of 85-95%. The performance results show that Fe-10 wt.% Zn-coated GA steel sheet (coating time 7 s) has better spot weldability, lower dynamic coefficient of friction (0.06-0.07 in lubrication), and better corrosion resistance compared to bare GA steel sheet. Uniform phosphate coating with globular crystal size of 2-5 µm was obtained on Fe-Zn flash-coated GA steel sheet. Hopeite was the main phosphate compound (77.9 wt.%) identified along with spencerite (13.6 wt.%) and phosphophyllite (8.5 wt.%).

  4. [Determination the chemical speciation of Cu, Zn, Fe and Mn in Radix Scutellariae by AAS].

    PubMed

    Miao, Shan; Sun, Ji-yuan; Xie, Yan-hua; Wang, Jian-bo; Shi, Xiao-peng; Ding, Yuan-yuan; Bi, Lin-lin; Gao, Shuang-bin; Wang, Si-wang

    2009-05-01

    An analysis method was developed to determine the chemical speciation of Cu, Zn, Fe and Mn in radix scutellariae decoction using atomic absorption spectroscopy(AAS). The decoction can be divided into suspension and soluble species by 0.45 microm filter membrane and the soluble species can be separated into organism and inorganic species by LSA-10 macroporous resin. These elements in water-soluble test samples can be divided into alcohol-soluble and water-soluble by adopting n-octyl alcohol-water allocation system in man-made gastric acidity. Then, the concentration of these elements was determined by AAS, which provided more chemical speciation information about these elements instead of the total amount of them only in radix scutellariae. Deteotion limit of Cu, Zn and Mn by using the method was all 0.01 microg x mL(-1) and was 0.02 microg x mL(-1) for Fe. The RSD was in the range of 1.5%-3.6% (n=11) and the recovery rate of soluble species and inorganic species were in range of 96.7%-105.0%. The method has been successfully applied to determine the chemical speciation of Cu, Zn, Fe and Mn in radix scutellariae, which was very important for overall study of radix scutellariae. PMID:19650506

  5. Preparation and photocatalytic properties of magnetically reusable Fe3O4@ZnO core/shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Wang, Jian; Yang, Jinghai; Li, Xiuyan; Wang, Dandan; Wei, Bing; Song, Hang; Li, Xuefei; Fu, Siwei

    2016-01-01

    Fe3O4@ZnO binary nanoparticles were synthesized by a simple two-step chemical method and characterized using various analytical instruments. TEM result proved the binary nanoparticles have core/shell structures and average particle size is 60 nm. Photocatalytic investigation of Fe3O4@ZnO core/shell nanoparticles was carried out using rhodamine B (RhB) solution under UV light. Fe3O4@ZnO core/shell nanoparticles showed enhanced photocatalytic performance in comparison with the as prepared ZnO nanoparticles. The enhanced photocatalytic activity for Fe3O4@ZnO might be resulting from the higher concentration of surface oxygen vacancies and the suppressing effect of the Fe3+ ions on the recombination of photoinduced electron-hole pairs. Magnetization saturation value (5.96 emu/g) of Fe3O4@ZnO core/shell nanoparticles is high enough to be magnetically removed by applying a magnetic field. The core/shell photocatalyst can be easily separated by using a commercial magnet and almost no decrease in photocatalytic efficiency was observed even after recycling six times.

  6. Presence of Fe3+ and Zn2+ promoted biotransformation of Cd-citrate complex and removal of metals from solutions.

    PubMed

    Qian, Jun-Wei; Tao, Yong; Zhang, Wen-Jie; He, Xiao-Hong; Gao, Ping; Li, Da-Ping

    2013-12-15

    The promotion to Cd-citrate complex biotransformation via addition of Fe(3+) and Zn(2+) was investigated. Single Fe(III)- or Zn-citrate complex was completely degraded by Pseudomonas sp. MBR, Cd-citrate complex was not. In the Cd-citrate media with molar ratio of 1:2 and 1:3, pH increase obtained from the metabolism of excess citrate slightly promoted the biotransformation of Cd-citrate complex, Cd remained in solutions. The presence of Fe(3+) and Zn(2+) resulted in complete biotransformation of Cd-citrate complex in the 1:1:2 Fe:Cd:citrate and Zn:Cd:citrate and 1:1:1:3 Fe:Zn:Cd:citrate media. Alkaline pH obtained from biotransformation of metal-citrate complexes caused almost complete removal of metals (>98%) through precipitation and co-precipitation. Pseudomonas sp. MBR potentially could be used to treat wastewater containing mixed citrate complexes of Fe(III), Zn and Cd. PMID:23820427

  7. Temperature dependent performance of Al/ZnCdS Schottky diode and charge transport analysis

    NASA Astrophysics Data System (ADS)

    Das, Mrinmay; Datta, Joydeep; Dey, Arka; Jana, Rajkumar; Ray, Partha Pratim

    2016-05-01

    Here we report the temperature dependent behaviour of Al/ZnCdS interface. In this regard, ZnCdS nanocomposite was synthesized by hydrothermal technique. Detailed study of schottky parameters including rectification ratio, ideality factor, series resistance and barrier height was performed. We explored the underlying charge transport phenomena through the Metal-semiconductor (MS) interface with the help of space charge limited current(SCLC) theory. A compartive analysis of carrier mobility and diffusion length was done.

  8. Influence of Fe doping on the structural, optical and magnetic properties of ZnS diluted magnetic semiconductor

    NASA Astrophysics Data System (ADS)

    Saikia, D.; Raland, RD.; Borah, J. P.

    2016-09-01

    Fe doped ZnS nanoparticles with different concentrations of Fe, synthesized by microwave assisted co-precipitation method have been reported. The incorporation of Fe2+ and Fe3+ ions into ZnS lattice are confirmed by X-ray diffraction (XRD) and Electron Paramagnetic resonance (EPR) study. XRD and High Resolution Transmission electron Microscope (HRTEM) results confirm the phase purity of the samples and indicate a reduction of the particle size with increase in Fe concentration. EDAX analysis confirms the presence of Zn, S and Fe in the samples. A yellow-orange emission peak is observed in Photoluminescence (PL) spectra which exhibits the Characteristic 4T2 (4G)-6A1 (6S) transition of Fe3+ ion. The room temperature magnetic studies as analyzed from M-H curves were investigated from vibrating samples magnetometer (VSM) which shows a weak ferro and superparamagnetic like behavior in 1% and 3% Fe-doped ZnS nanocrystals, whereas; at 10% Fe-doping concentrations, antiferromagnetism behavior is achieved. The ZFC-FC measurement reveals that the blocking temperature of the nanoparticle is above the room temperature.

  9. Growth mechanism of ZnO nanorod/Fe3O4 nanoparticle composites and their photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Wang, Wenda; Yu, Leiming; Yang, Hanjia; Hong, Kunquan; Qiao, Zhenfang; Wang, Hai

    2015-11-01

    ZnO nanorods/Fe3O4 nanocomposites as the recyclable photocatalyst were synthesized by a co-precipitation method, with microwave assistant by dropping alkaline solution with Fe3O4 nanoparticles into the aqueous of zinc salt. These Fe3O4 nanoparticles were the nucleated centers for the ZnO nanorods growth so that these nanorods ended with aggregated Fe3O4 nanoparticles. The growth processes and mechanism are explained as those insoluble zinc hydroxides prefer to nucleate on the surface of Fe3O4 nanoparticles (heterogeneous nucleation) rather than nucleated as isolated ZnO nanostructures (homogeneous nucleation). These nanocomposites have strong photocatalytic ability to reduce RhB and moderate magnetization, which make them being good recyclable photocatalysts.

  10. Optical properties of heusler alloys Co2FeSi, Co2FeAl, Co2CrAl, and Co2CrGa

    NASA Astrophysics Data System (ADS)

    Shreder, E. I.; Svyazhin, A. D.; Belozerova, K. A.

    2013-11-01

    The results of an investigation of optical properties and the calculations of the electronic structure of Co2FeSi, Co2FeAl, Co2CrAl, and Co2CrGa Heusler alloys are presented. The main focus of our attention is the study of the spectral dependence of the real part (ɛ1) and imaginary part (ɛ2) of the dielectric constant in the range of wavelengths λ = 0.3-13 μm using the ellipsometric method. An anomalous behavior of the optical conductivity σ(ω) has been found in the infrared range in the Co2CrAl and Co2CrGa alloys, which differs substantially from that in the Co2FeSi and Co2FeAl alloys. The results obtained are discussed based on the calculations of the electronic structure.

  11. Synthesis of Glycerol Carbonate by Transesterification of Glycerol with Urea Over Zn/Al Mixed Oxide.

    PubMed

    Ryu, Young Bok; Baek, Jae Ho; Kim, Yangdo; Lee, Man Sig

    2015-01-01

    Reactions of glycerol carbonate using glycerol and urea have been carried out previously using ZnSO4 and ZnO catalysts, and high yields have been reported using ZnSO4 as catalyst. However, this salt is soluble in glycerol, and recycling of catalyst is difficult after the reaction. In this study, we prepared a mixed metal oxide catalyst using Zn and Al, and this catalyst consisted of a mixture of ZnO and ZnAl2O4. We confirmed the conversion of glycerol and the yield of glycerol carbonate of the amount of Al. As a result, we obtained a yield of 82.3% and a conversion of 82.7%. In addition we obtained high yield in recycling of catalyst. The yield of the glycerol carbonate increases with an increase of acid and base site of catalysts and the highest catalytic activity was obtained when acid/base ratio was approx. 1. From this result, we may conclude that the acid and base site density and ratio of catalysts were very important parameters in the synthesis of glycerol carbonate from urea and glycerol. PMID:26328352

  12. Effects of Interfacial Layers Fracture on the Dissolution Mechanism of Solid Fe in Liquid Al

    NASA Astrophysics Data System (ADS)

    Rezaei, H.; Akbarpour, M. R.; Shahverdi, H. R.

    2015-07-01

    Solid Fe and liquid Al interaction was studied in the temperature range of 750-900°C by immersion tests in the absence of convection to better understand interfacial reactions during the first instances of immersion (10-80 s). Solidified interface profiles were characterized using a scanning electron microscope and an electron probe micro-analyzer. The results showed the formation of a transition layer with a composition close to pure Fe on the Fe side as a result of Al diffusion from the melt into the solid at initial times of the immersion test, before the formation of an intermetallic compound. At longer immersion times, two intermetallic layers were observed, Fe2Al5 and FeAl3. With increasing immersion time, the intermetallic compounds were thickened, and cracks formed at the interface layers. The formation of cracks accelerated the fracture of the interfacial layers and enhanced the Al diffusion toward solid Fe. As a result of the detachment and dissolution of the intermetallic phases in liquid Al, precipitates of FeAl3 with needle-like morphology were found in the Al phase. A model is proposed for the interface reaction of solid Fe with liquid Al at the first instance of immersion.

  13. Characterization of nanocrystalline ZnO:Al films by sol-gel spin coating method

    SciTech Connect

    Gareso, P. L. Rauf, N. Juarlin, E.; Sugianto,; Maddu, A.

    2014-09-25

    Nanocrystalline ZnO films doped with aluminium by sol-gel spin coating method have been investigated using optical transmittance UV-Vis and X-ray diffraction (X-RD) measurements. ZnO films were prepared using zinc acetate dehydrate (Zn(CH{sub 3}COO){sub 2}@@‡2H{sub 2}O), ethanol, and diethanolamine (DEA) as a starting material, solvent, and stabilizer, respectively. For doped films, AlCl{sub 3} was added to the mixture. The ZnO:Al films were deposited on a transparent conductive oxide (TCO) substrate using spin coating technique at room temperature with a rate of 3000 rpm in 30 sec. The deposited films were annealed at various temperatures from 400°C to 600°C during 60 minutes. The transmittance UV-Vis measurement results showed that after annealing at 400°C, the energy band gap profile of nanocrystalline ZnO:Al film was a blue shift. This indicated that the band gap of ZnO:Al increased after annealing due to the increase of crystalline size. As the annealing temperature increased the bandgap energy was a constant. In addition to this, there was a small oscillation occurring after annealing compared to the as–grown samples. In the case of X-RD measurements, the crystalinity of the films were amorphous before annealing, and after annealing the crystalinity became enhance. Also, X-RD results showed that structure of nanocrystalline ZnO:Al films were hexagonal polycrystalline with lattice parameters are a = 3.290 Å and c = 5.2531 Å.

  14. Facile synthesis of p-type Zn-doped α-Fe2O3 films for solar water splitting

    NASA Astrophysics Data System (ADS)

    Kuo, Chun-Lin; Hsu, Yu-Kuei; Lin, Yan-Gu

    2014-10-01

    A facile and simple fabrication of Zn-doped α-Fe2O3 thin films as a photocathode for solar hydrogen generation was proposed in this report. Transparent Zn-doped α-Fe2O3 films were prepared by a deposition-annealing (DA) process using nontoxic iron(III) chloride as the Fe precursor and zinc chloride as a acceptor dopant, followed by annealing at 550 °C in air. In terms of the structural examination of as-grown samples, X-ray diffraction analysis demonstrated an increase in the lattice parameters of Zn incorporated in Fe2O3 by substituting Fe in the host lattice. No second phase was determined, indicating no phase separation in the ternary materials. Energy dispersive spectroscopy results demonstrated that Zn, Fe, and O elements existed in the deposits. Furthermore, impedance measurements show that the Zn-dopant serves as an hole acceptor and increases the acceptor concentration by increasing concentration of zinc precursor. Significantly, the photoelectrochemical measurements exhibited remarkable cathodic current, corresponding to the reduction reaction of hydrogen. Finally, the optimum photocurrent can be achieved by controlled variation of the Fe and Zni precursor concentration, annealing conditions, and the number of DA cycles. According to our investigation, the understandings of morphology effect on PEC activity give the blueprint for materials design in the application of solar hydrogen.

  15. Fabrication and properties of Mn 0.5Zn 0.5Fe 2O 4 nanofibers

    NASA Astrophysics Data System (ADS)

    Li, Qiailing; Wang, Wenting

    2010-08-01

    Zn-doped α-FeOOH nanofiber was synthesized by coprecipitation method. Then the α-FeOOH was enwraped by the complex of the Mn 2+ and citric acid. The morphology of α-FeOOH did not transform after the calcination process and Mn 0.5Zn 0.5Fe 2O 4 nanofiber was successfully prepared. The phase, morphology, particle diameter and the magnetic properties of samples were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The results indicated that Mn 0.5Zn 0.5Fe 2O 4 nanofibers with an aspect ratio over 40 and a diameter of 20 nm were prepared. Compared with the amorphous Mn 0.5Zn 0.5Fe 2O 4, the anisotropy of the Mn 0.5Zn 0.5Fe 2O 4 nanofiber increased, resulting in the higher coercivity and magnetization of the obtained sample. With an increase in the calcination temperature, the diameter and the saturation magnetization of the sample increased, while the aspect ratio and coercivity decreased. The coercivity of the sample obtained at 700 °C was maximal (up to 185.4 Oe). The saturation magnetization of the sample obtained at 900 °C was maximal (up to 65.3 emu/g). The use of citric acid method prevented the presence of Mn(OH) 2, resulting in the decrease of the calcination temperature.

  16. The effect of Ti addition on oxidation behavior of FeAl intermetallic alloy

    SciTech Connect

    Li, D.; Lin, D.

    1997-12-31

    The influence of Ti addition on the high temperature oxidation behaviors of FeAl intermetallic alloys in air at 1,000 C and 1,100 C have been investigated. The oxidation kinetics of FeAl alloys were examined by the weight gain method and oxide products were examined by XRD, SEM, EDS and EPMA. The results showed that the oxidation kinetic curves of both Ti-doped and binary Fe-36.5Al alloys were described as different parabolas followed the formula: ({Delta}W/S){sup 2} = K{sub p}t. The parabolic rate constant, K{sub p} values are about 2.4 and 3.3 mg{sup 2}cm{sup {minus}4}h{sup {minus}1} for Fe-36.5Al alloy and about 1.3 and 2.0 mg{sup 2}cm{sup {minus}4}h{sup {minus}1} for Fe-36.5Al-2Ti alloy when oxidizing at 1,000 C and 1,100 C respectively. The difference between Fe-36.5Al and Fe-36.5Al-2Ti alloy is not only in the surface morphology but also in the phase components. In the surface there is only {alpha}-Al{sub 2}O{sub 3} oxide for the Fe-36.5Al alloy while there are {alpha}-Al{sub 2}O{sub 3} and TiO oxide for the Fe-36.5Al-2Ti alloy. The effects of Ti addition on the oxidation resistance of FeAl alloy were discussed based on the microstructural evidence.

  17. Structural and Morphological Properties of Al doped ZnO Nanoparticles

    NASA Astrophysics Data System (ADS)

    Akdağ, A.; Budak, H. F.; Yılmaz, M.; Efe, A.; Büyükaydın, M.; Can, M.; Turgut, G.; Sönmez, E.

    2016-04-01

    Zinc oxide nanoparticles have a wide area of use because of their unique properties such as catalytic, electrical, and optical properties and low cost. Since the suitable additive materials can be changed the electrical and optical properties of zinc oxide, the demand of the industrial commercial area to the zinc oxide increased. In this study, Al doped ZnO nanoparticles produced by using the methods of reduction thought having materials of the Zn(NO)3, AlCl3 and NaOH. XRD, SEM and EDS used for making analyzing of structural and dimensional of particles. The analyses show that the large amount of the Al3+ ions did nut substitute with Zn2+ successfully with the reduction method. XRD and EDS results confirm this situation.

  18. Wetting and Interfacial Chemistry of SnZnCu Alloys with Cu and Al Substrates

    NASA Astrophysics Data System (ADS)

    Fima, Przemysław; Pstruś, Janusz; Gancarz, Tomasz

    2014-05-01

    Wetting of Cu and Al pads by Sn-Zn eutectic-based alloys with 0.5, 1, and 1.5 wt.% of Cu was studied at 250 °C, in the presence of ALU33® flux, with wetting times of 15, 30, 60, and 180 s, respectively. With increasing wetting time the wetting angle decreases only slightly and the angles on Cu pads are higher than those on Al pads. Selected, solidified solder-pad couples were cross-sectioned and subjected to SEM-EDS study of the interfacial microstructure. The results revealed that the microstructure of the SnZnCu/Cu interface is much different from SnZnCu/Al interface. In the first case continuous interlayers are observed while in the latter case there is no interlayer but the alloy dissolves the substrate along grain boundaries.

  19. Intercalation of diclofenac in modified Zn/Al hydrotalcite-like preparation

    NASA Astrophysics Data System (ADS)

    Heraldy, E.; Suprihatin, R. W.; Pranoto

    2016-02-01

    The intercalation of a pharmaceutically active material diclofenac into modified Zn/Al Hydrotalcite-like (Zn/Al HTlc) preparation has been investigated by the coprecipitation and ion exchange method, respectively. The synthetic materials were characterized using X- Ray Diffraction (XRD); Fourier transforms infrared spectroscopy (FTIR); Scanning Electron Microscope (SEM); X-Ray Fluorescence (XRF) and surface area analyzer. The results show that the basal spacing of the product was expanded to 11.03 A for direct synthesis and 10.68 A for indirect synthesis, suggesting that diclofenac anion was intercalated into Zn/Al HTlc and arranged in a tilted bilayer fashion and the specific surface area of material increased after the intercalation of diclofenac.

  20. Structural properties of ZnO:Al films produced by the sol–gel technique

    SciTech Connect

    Zaretskaya, E. P. Gremenok, V. F.; Semchenko, A. V.; Sidsky, V. V.; Juskenas, R. L.

    2015-10-15

    ZnO:Al films are produced by sol–gel deposition at temperatures of 350–550°C, using different types of reagents. Atomic-force microscopy, X-ray diffraction analysis, Raman spectroscopy, and optical transmittance measurements are used to study the dependence of the structural, morphological, and optical properties of the ZnO:Al coatings on the conditions of deposition. The optical conditions for the production of ZnO:Al layers with preferred orientation in the [001] direction and distinguished by small surface roughness are established. The layers produced in the study possess optical transmittance at a level of up to 95% in a wide spectral range and can be used in optoelectronic devices.

  1. Gas sensing properties of Al-doped ZnO for UV-activated CO detection

    NASA Astrophysics Data System (ADS)

    Dhahri, R.; Hjiri, M.; El Mir, L.; Bonavita, A.; Iannazzo, D.; Latino, M.; Donato, N.; Leonardi, S. G.; Neri, G.

    2016-04-01

    Al-doped ZnO (AZO) samples were prepared using a modified sol-gel route and charaterized by means of trasmission electron microscopy, x-ray diffraction and photoluminescence analysis. Resistive planar devices based on thick films of AZO deposited on interdigitated alumina substrates were fabricated and investigated as UV light activated CO sensors. CO sensing tests were performed in both dark and illumination condition by exposing the samples to UV radiation (λ  =  400 nm).Under UV light, Al-doped ZnO gas sensors operated at lower temperature than in dark. Furthermore, by photoactivation we also promoted CO sensitivity and made signal recovery of AZO sensors faster. Results demonstrate that Al-doped ZnO might be a promising sensing material for the detection of CO under UV illumination.

  2. Formation of a ZnO overlayer in industrial Cu/ZnO/Al2 O3 catalysts induced by strong metal-support interactions.

    PubMed

    Lunkenbein, Thomas; Schumann, Julia; Behrens, Malte; Schlögl, Robert; Willinger, Marc G

    2015-04-01

    In industrially relevant Cu/ZnO/Al2 O3 catalysts for methanol synthesis, the strong metal support interaction between Cu and ZnO is known to play a key role. Here we report a detailed chemical transmission electron microscopy study on the nanostructural consequences of the strong metal support interaction in an activated high-performance catalyst. For the first time, clear evidence for the formation of metastable "graphite-like" ZnO layers during reductive activation is provided. The description of this metastable layer might contribute to the understanding of synergistic effects between the components of the Cu/ZnO/Al2 O3 catalysts. PMID:25683230

  3. Study of structural and optical properties of ZnAlQ5 (zinc aluminum quinolate) organic phosphor for OLED applications

    NASA Astrophysics Data System (ADS)

    Nagpure, I. M.; Painuly, Deepshikha; Rabanal, Maria Eugenia

    2016-05-01

    The various composition of ZnAlQ5 such as Zn1.5A10.5Q5, Zn1Al1Q5, Zn0.5Al1.5Q5 organic phosphors were prepared via simple cost effective co-precipitation method. The FTIR, SEM, photoluminescence analysis of the prepared phosphors were reported. ZnQ2 and AlQ3 were also prepared by similar method and their properties were compared with different composition of ZnAlQ5. The structural elucidation in the form of stretching frequencies of chemical bonds of the prepared phosphor was carried out using Fourier Transform Infrared Spectroscopy (FTIR). The stretching frequency analysis confirms the formation of prepared phosphor materials. The SEM analysis shows the surface morphological behavior of prepared phosphor materials. Greenish photoluminescence were observed at 505 to 510 nm for the different composition of ZnAlQ5,in which Zn1.5Al0.5Q5 shows maximum luminescence intensity at 505 nm. PL emission of ZnQ2 was observed at 515 nm, while for AlQ3 at 520 nm. The blue shift of 10 nm was observed in Zn1.5A10.5Q5 due to modification of energy level due to presence of Zn2+ and Al3+. The enhancement in PL intensity was observed in Zn1.5A10.5Q5 compared to the other composition due to transfer of energy between Zn2+ and quinolate complex. Optical properties of the prepared materials were evaluated for possible applications in organic light emitting devices (OLED).

  4. Surfactant-free synthesis of octahedral ZnO/ZnFe2O4 heterostructure with ultrahigh and selective adsorption capacity of malachite green

    PubMed Central

    Liu, Jue; Zeng, Min; Yu, Ronghai

    2016-01-01

    A new octahedral ZnO/ZnFe2O4 heterostructure has been fabricated through a facile surfactant-free solvothermal method followed by thermal treatment. It exhibits a record-high adsorption capacity (up to 4983.0 mg·g−1) of malachite green (MG), which is a potentially harmful dye in prevalence and should be removed from wastewater and other aqueous solutions before discharging into the environment. The octahedral ZnO/ZnFe2O4 heterostructure also demonstrates strong selective adsorption towards MG from two kinds of mixed solutions: MG/methyl orange (MO) and MG/rhodamine B (RhB) mixtures, indicating its promise in water treatment. PMID:27142194

  5. Surfactant-free synthesis of octahedral ZnO/ZnFe2O4 heterostructure with ultrahigh and selective adsorption capacity of malachite green

    NASA Astrophysics Data System (ADS)

    Liu, Jue; Zeng, Min; Yu, Ronghai

    2016-05-01

    A new octahedral ZnO/ZnFe2O4 heterostructure has been fabricated through a facile surfactant-free solvothermal method followed by thermal treatment. It exhibits a record-high adsorption capacity (up to 4983.0 mg·g‑1) of malachite green (MG), which is a potentially harmful dye in prevalence and should be removed from wastewater and other aqueous solutions before discharging into the environment. The octahedral ZnO/ZnFe2O4 heterostructure also demonstrates strong selective adsorption towards MG from two kinds of mixed solutions: MG/methyl orange (MO) and MG/rhodamine B (RhB) mixtures, indicating its promise in water treatment.

  6. Surfactant-free synthesis of octahedral ZnO/ZnFe2O4 heterostructure with ultrahigh and selective adsorption capacity of malachite green.

    PubMed

    Liu, Jue; Zeng, Min; Yu, Ronghai

    2016-01-01

    A new octahedral ZnO/ZnFe2O4 heterostructure has been fabricated through a facile surfactant-free solvothermal method followed by thermal treatment. It exhibits a record-high adsorption capacity (up to 4983.0 mg·g(-1)) of malachite green (MG), which is a potentially harmful dye in prevalence and should be removed from wastewater and other aqueous solutions before discharging into the environment. The octahedral ZnO/ZnFe2O4 heterostructure also demonstrates strong selective adsorption towards MG from two kinds of mixed solutions: MG/methyl orange (MO) and MG/rhodamine B (RhB) mixtures, indicating its promise in water treatment. PMID:27142194

  7. Free energies of (Co, Fe, Ni, Zn)Fe2O4 spinels and oxides in water at high temperatures and pressure from density functional theory: results for stoichiometric NiO and NiFe2O4 surfaces

    NASA Astrophysics Data System (ADS)

    O'Brien, C. J.; Rák, Z.; Brenner, D. W.

    2013-11-01

    A set of effective chemical potentials (ECPs) are derived that connect energies of (Co, Fe, Ni, Zn)Fe2O4 spinels and oxides calculated at 0 K from density functional theory (DFT) to free energies in high temperature and pressure water. The ECPs are derived and validated by solving a system of linear equations that combine DFT and experimental free energies for NiO, ZnO, Fe2O3, Fe3O4, FeO(OH), CoFe2O4, ZnFe2O4, NiFe2O4 and H2O. To connect to solution phase chemistry, a set of ECPs are also derived for solvated Ni2+, Zn2+, Fe2+ and Fe3+ ions using an analogous set of linear equations and the solid ECPs. The ECPs are used to calculate free energies of low index stoichiometric surfaces of nickel oxide (NiO) and nickel ferrite (NiFe2O4) in water as a function of temperature from 300 to 600 K at a pressure of 155 bar. Surface denuding at high temperatures is predicted, the implications of which for the formation of oxide corrosion products on heat transfer surfaces in light-water nuclear reactors are discussed.

  8. [Cathodoluminescent characteristics of green-emitting ZnAl2O4:Mn thin film phosphors].

    PubMed

    Lou, Zhi-dong; Xu, Zheng; Yi, Lan-jie; Yang, Sheng-yi

    2008-06-01

    Green electroluminescence was obtained from thin films of ZnAl2O4: Mn prepared by rf magnetron sputtering onto thick insulating ceramic sheets. Photoluminescence and stress-stimulated luminescence was obtained for Mn-doped ZnAl2O4 powder synthesized by the solid phase reaction. Since it is extremely stable chemically and thermally, ZnAl2O4 may emerge as an alternative choice to sulphide-based phosphors. In the present paper, thin films of ZnAl2O4: Mn were grown on aluminosilicate ceramic plates using spray pyrolysis of aqueous solutions. The cathodoluminescence (CL) properties of the films under low to medium excitation voltage (<5 kV) were investigated. The films exhibited green CL after being annealed at temperatures above 550 degrees C, which corresponds to the transition between 4 T1 and (6)A1 of Mn2+ ions located in the tetra coordination of the Zn2+ site in the spinel structure. The chromaticity coordinates were x = 0.150 and y = 0.734 with a dominant wavelength of 525 nm and an 82% color purity. The CL luminance and efficiency depended on the excitation voltage and current density. Saturation effects were observed as the current density increased. A luminance of 540 cd x m(-2) and an efficiency of 4.5 lm x W(-1) were obtained at an excitation voltage of 4 kV with a current density of 38 microA x cm(-2). PMID:18800691

  9. Highly transparent and conductive ZnO:Al thin films prepared by vacuum arc plasma evaporation

    NASA Astrophysics Data System (ADS)

    Miyata, Toshihiro; Minamino, Youhei; Ida, Satoshi; Minami, Tadatsugu

    2004-07-01

    A vacuum arc plasma evaporation (VAPE) method using both oxide fragments and gas sources as the source materials is demonstrated to be very effective for the preparation of multicomponent oxide thin films. Highly transparent and conductive Al-doped ZnO (AZO) thin films were prepared by the VAPE method using a ZnO fragment target and a gas source Al dopant, aluminum acethylacetonate (Al(C5H7O2)3) contained in a stainless steel vessel. The Al content in the AZO films was altered by controlling the partial pressure (or flow rate) of the Al dopant gas. High deposition rates as well as uniform distributions of resistivity and thickness on the substrate surface were obtained on large area glass substrates. A low resistivity on the order of 10-4 Ω cm and an average transmittance above 80% in the visible range were obtained in AZO thin films deposited on glass substrates. .

  10. Influence of Fe doping on the structural, optical and acetone sensing properties of sprayed ZnO thin films

    SciTech Connect

    Prajapati, C.S.; Kushwaha, Ajay; Sahay, P.P.

    2013-07-15

    Graphical abstract: All the films are found to be polycrystalline ZnO possessing hexagonal wurtzite structure. The intensities of all the peaks are diminished strongly in the Fe-doped films, indicating their lower crystallinity as compared to the undoped ZnO film. The average crystallite size decreases from 35.21 nm (undoped sample) to 15.43 nm (1 at% Fe-doped sample). - Highlights: • Fe-doped ZnO films show smaller crystallinity with crystallite size: 15–26 nm. • Optical band gap in ZnO films decreases on Fe doping. • Fe-doped films exhibit the normal dispersion for the wavelength range 450–600 nm. • PL spectra of the Fe-doped films show quenching of the broad green-orange emission. • Acetone response of the Fe-doped films increases considerably at 300 °C. - Abstract: The ZnO thin films (undoped and Fe-doped) deposited by chemical spray pyrolysis technique have been analyzed by X-ray powder diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). Results show that all the films possess hexagonal wurtzite structure of zinc oxide having crystallite sizes in the range 15–36 nm. On 1 at% Fe doping, the surface roughness of the film increases which favors the adsorption of atmospheric oxygen on the film surface and thereby increase in the gas response. Optical studies reveal that the band gap decreases due to creation of some defect energy states below the conduction band edge, arising out of the lattice disorder in the doped films. The refractive index of the films decreases on Fe doping and follows the Cauchy relation of normal dispersion. Among all the films examined, the 1 at% Fe-doped film exhibits the maximum response (∼72%) at 300 °C for 100 ppm concentration of acetone in air.

  11. Enhanced spin signal in nonlocal devices based on a ferromagnetic CoFeAl alloy

    NASA Astrophysics Data System (ADS)

    Bridoux, G.; Costache, M. V.; Van de Vondel, J.; Neumann, I.; Valenzuela, S. O.

    2011-09-01

    We systematically study the nonlocal spin signal in lateral spin valves based on CoFeAl injectors and detectors and compare the results with identically fabricated devices based on CoFe. The devices are fabricated by electron beam evaporation at room temperature. We observe a > 10-fold enhancement of the spin signal in the CoFeAl devices. We explain this increase as due to the formation of a highly spin-polarized Co2FeAl Heusler compound with large resistivity. These results suggest that Heusler compounds are promising candidates as spin polarized electrodes in lateral spin devices for future spintronic applications.

  12. Effect of 0.3 wt.% Al Addition in Flowing Liquid Zinc on the Erosion-Corrosion Behavior of Fe-3.5 wt.% B Alloy

    NASA Astrophysics Data System (ADS)

    Wang, Yong; Xing, Jiandong; Ma, Shengqiang; Liu, Guangzhu; Fu, Hanguang; Jia, Sen

    2015-06-01

    The effects of 0.3 wt.% Al added to flowing liquid zinc on the corrosion inhibition and erosion-corrosion interfacial characteristics of Fe-3.5 wt.% B alloy were investigated in order to separate the pure erosion rate from the total erosion-corrosion rate and further study the erosion-corrosion interaction created by flowing zinc. The result indicated that the erosion-corrosion rate increased slowly and then sharply thereafter, while the corrosion-inhibition rate increased linearly and slowly at a bath temperature of 460-550 °C. The corrosion-inhibition efficiency of 0.3 wt.% Al addition in the flowing liquid zinc bath was significantly reduced and then enhanced with increasing bath temperatures, depending on the interfacial microstructures after Al-corrosion inhibition. A uniform and continuous Fe2Al5Zn x inhibition layer, which suppressed the corrosion reaction of iron and zinc, formed on the erosion-corrosion interface of the Fe-3.5 wt.% B alloy, thereby reducing the spallation of anticaustic Fe2B skeleton. Moreover, the gradual deterioration of the inhibition layer led to a reduction in the corrosion-inhibition ability. The present results indicate that, due to the beneficial Al-corrosion inhibition effect, the corrosion-inhibition rate as the pure erosion rate of Fe-3.5 wt.% B in flowing liquid zinc can be well separated from the erosion-corrosion rate by adding 0.3 wt.% Al to flowing liquid zinc bath.

  13. Effect of silicon alloying additions on growth temperature and primary spacing of Al{sub 3}Fe in Al-8wt%Fe alloy

    SciTech Connect

    Liang, D.; Jones, H.; Gilgien, P.

    1995-05-15

    Alloys of Al-8.4Fe-1.7Si, Al-8.5Fe-3.4Si and Al-8.5Fe-5.6Si (wt%) designated A, B and C, respectively, were prepared from high purity (99.99%) aluminum, Japanese electrolytic iron (99.9%) and superpure silicon (99.99%). Melting was carried out in a recrystallized alumina crucible by using a Radyne induction furnace and was followed by chill casting under flowing argon into steel molds of cavity dimension 15 mm thick, 50 mm wide and 150 mm high. Rods 3 mm in diameter were fabricated directly from the ingots. Lengths of the rods, which were contained in 3 mm bore tubular alumina crucibles, were melted in a Bridgman growth facility. After maintaining the melt at 100K above the liquidus temperatures liquidus: 1,118, 1,108 and 1,092 K for 1.7, 3.4 and 5.6 wt%Si, respectively, for about 10 minutes, crucibles containing the melt were withdrawn at a speed of 0.34 mm/s into a water bath. The following conclusions can be drawn from analysis of the specimens. Addition of silicon to Al-8wt%Fe alloy results in an increase in growth undercooling and primary spacing of Al{sub 3}Fe dendrites Bridgman grown at 0.34 mm/s and 10K/mm. This increase in growth undercooling, relative to predicted local liquidus temperatures which have been corrected for observed macrosegregation of Fe, is in good accord with the predictions of the Kurz-Giovanola-Trivedi model for needle-like dendrite growth. The silicon content of the Al{sub 3}Fe dendrites obtained is consistent with previously reported measurements for a range of cast Al-Fe-Si alloys.

  14. Fe-Al layered double hydroxides in bromate reduction: Synthesis and reactivity.

    PubMed

    Chitrakar, Ramesh; Makita, Yoji; Sonoda, Akinari; Hirotsu, Takahiro

    2011-02-15

    This study presents a rare use of layered double hydroxides of Fe(II) and Al(III) (Fe-Al LDH), as reported for the first time for bromate removal from aqueous solutions. The Fe-Al LDH samples were prepared with Fe/Al molar ratios of 1-4 using a co-precipitation method at pH 7, with subsequent hydrothermal treatment at 120°C. The Fe-Al LDH (molar ratio of Fe/Al=1, 2) with a layered structure exhibited nearly complete removal of bromate from initial concentration of 100μmol/dm(3) at a wide pH range of 4.0-10.5 over a 2h reaction period; the residual bromate concentration in the solution was lower than the detection limit of 0.07μmol/dm(3) (9μg-BrO(3)(-)/dm(3)). During the reaction period, bromide was released into the solution via a reduction process. Reactivity of Fe-Al LDH with a Fe/Al molar ratio of 2 did not decrease the bromate reduction efficiency during 30days. PMID:21126742

  15. Enhanced Room Temperature Ferromagnetism by Fe Doping in Zn0.96Cu0.04O Diluted Magnetic Semiconductors

    NASA Astrophysics Data System (ADS)

    Muthukumaran, S.; Ashokkumar, M.

    2016-02-01

    Zn0.96- x Cu0.04Fe x O (0 ≤ x ≤ 0.04) nanoparticles synthesized via the sol-gel technique had a hexagonal wurtzite ZnO structure without any Fe/Cu-related secondary phases. The crystallite size was reduced from Fe = 0% (23 nm) to Fe = 4% (16 nm) due to the suppression of grain surface growth by foreign impurities. Doping of higher Fe concentrations into Zn-Cu-O suppressed the ultra-violet (UV) emission band and balanced the defect-related visible emissions. The decrease of the UV and green emission intensity ratio ( I UV/ I green) and the UV and blue emission intensity ratio ( I UV/ I blue) in photoluminescence spectra implied an increase of defect states with the increase of Fe concentrations. All the samples showed clear room temperature ferromagnetism. The saturation magnetization was increased by Fe co-doping which was attributed to the interaction between Fe-Fe ions. X-ray photoelectron spectra confirmed the absence of secondary phases like Fe3O4.

  16. Preparation of Al-Cr-Fe Coatings by Heat Treatment of Electrodeposited Cr/Al Composite Coatings

    NASA Astrophysics Data System (ADS)

    Zhang, Min; Chen, Chang'an; Zhang, Guikai; Rao, Yongchu; Ling, Guoping

    Al-Cr-Fe coatings have been widely used in the surface engineering field of materials, due to their excellent corrosion resistance to water vapor and fused salt deposits. In this study, a new two-step approach was developed to prepare Al-Cr-Fe coatings on surfaces of SUS430 stainless steels. First, the Cr/Al composite coatings were prepared by electrodepositing Cr from aqueous solution then electrodepositing Al from AlCl3-1-ethyl-3-methyl-imidazolium chloride (AlCl3-EMIC) ionic liquid on SUS430 stainless steel substrate. In the second, heat treatment of the Cr/Al composite coatings was carried out to acquire Al-Cr-Fe coatings. Effects of the thickness of Cr/Al composite coatings, the time and temperature of heat treatment on composition and phase structure of alloy layers were studied by using scanning electron microscope (SEM), backscattered electron (BSE), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The structure transformation process and formation mechanism of Al-Cr-Fe coatings were discussed.

  17. Site location of Al-dopant in ZnO lattice by exploiting the structural and optical characterisation of ZnO:Al thin films

    NASA Astrophysics Data System (ADS)

    Nakrela, A.; Benramdane, N.; Bouzidi, A.; Kebbab, Z.; Medles, M.; Mathieu, C.

    The zinc oxide thin films, highly transparent, doped aluminium were prepared on glass substrates by the reactive chemical spray method. The incorporation nature of Al atoms in the ZnO lattice was determined by X-ray diffraction and optical analyses. Indeed, for low doping ⩽2%, the results of X-ray spectra analysis show a simultaneous reduction of lattice parameters (a and c), this variation, which follows VEGARD's law, tends to indicate a substitution of Zn by Al. By against for doping >2% the increase in the lattice parameters thus the grain sizes, in accordance with the VEGARD's law can be explained by occupation of the interstitial sites by Al atoms. Beyond 4%, the material tends to get disorderly and the crystallites orientation is random. The studied optical properties show that the variation of the optical gap follows a law of the x3/2 form for x < 3% (x is the aluminium atom fraction incorporated in the ZnO lattice). The granular structure is fairly visible and some local growths are disrupted. The crystallite size at low enlargement is coherent with the XRD results.

  18. Investigation on thermo physical characteristics of ethylene glycol based Al:ZnO nanofluids

    NASA Astrophysics Data System (ADS)

    R, Kiruba.; George, Ritty; M, Gopalakrishnan.; A, Kingson Solomon Jeevaraj.

    2015-06-01

    The present work describes the experimental aspects of viscosity and thermal conductivity characteristics of nanofluids. Aluminium doped zinc oxide nanostructures were synthesized by chemical precipitation method. Ultrasonic technique is used to disperse the nanostructures in ethylene glycol. Structural and morphological properties of Al doped ZnO nanostructures are characterized using X-ray diffractometer and scanning electron microscopic technique. The effect of concentration and temperature on thermo-physical properties of Al/ZnO nanofluids is also investigated. The experimental results showed there is enhancement in thermal conductivity with rise in temperature which can be utilized for coolant application.

  19. Mechanical Responses of Superlight β-Based Mg-Li-Al-Zn Wrought Alloys under Resonance

    NASA Astrophysics Data System (ADS)

    Song, Jenn-Ming; Lin, Yi-Hua; Su, Chien-Wei; Wang, Jian-Yih

    2009-05-01

    To extend the application of lightweight Mg alloys in the automotive industry, this study suggests a β-based Mg-Li alloy (LAZ1110) with superior vibration fracture resistance by means of material design. In the cold-rolled state, a strengthened β matrix by the additions of Al and Zn, as well as intergranular platelike α precipitates, which are able to stunt the crack growth, contributes to a comparable vibration life with commercial Mg-Al-Zn alloys under a similar strain condition.

  20. Investigation on thermo physical characteristics of ethylene glycol based Al:ZnO nanofluids

    SciTech Connect

    Kiruba, R. E-mail: drkingson@karunya.edu; George, Ritty; Gopalakrishnan, M.; Kingson Solomon Jeevaraj, A.

    2015-06-24

    The present work describes the experimental aspects of viscosity and thermal conductivity characteristics of nanofluids. Aluminium doped zinc oxide nanostructures were synthesized by chemical precipitation method. Ultrasonic technique is used to disperse the nanostructures in ethylene glycol. Structural and morphological properties of Al doped ZnO nanostructures are characterized using X-ray diffractometer and scanning electron microscopic technique. The effect of concentration and temperature on thermo-physical properties of Al/ZnO nanofluids is also investigated. The experimental results showed there is enhancement in thermal conductivity with rise in temperature which can be utilized for coolant application.

  1. Al-doped ZnO contact to CdZnTe for x- and gamma-ray detector applications

    NASA Astrophysics Data System (ADS)

    Roy, U. N.; Camarda, G. S.; Cui, Y.; Gul, R.; Hossain, A.; Yang, G.; Mundle, R. M.; Pradhan, A. K.; James, R. B.

    2016-06-01

    The poor adhesion of common metals to CdZnTe (CZT)/CdTe surfaces has been a long-standing challenge for radiation detector applications. In this present work, we explored the use of an alternative electrode, viz., Al-doped ZnO (AZO) as a replacement to common metallic contacts. ZnO offers several advantages over the latter, such as having a higher hardness, a close match of the coefficients of thermal expansion for CZT and ZnO, and better adhesion to the surface of CZT due to the contact layer being an oxide. The AZO/CZT contact was investigated via high spatial-resolution X-ray response mapping for a planar detector at the micron level. The durability of the device was investigated by acquiring I-V measurements over an 18-month period, and good long-term stability was observed. We have demonstrated that the AZO/CZT/AZO virtual-Frisch-grid device performs fairly well, with comparable or better characteristics than that for the same detector fabricated with gold contacts.

  2. Preparation and characterisation of ZnFe 2O 4/ZnO polymer nanocomposite sensors for the detection of alcohol vapours

    NASA Astrophysics Data System (ADS)

    Arshak, K.; Moore, E.; Cunniffe, C.; Nicholson, M.; Arshak, A.

    2007-07-01

    During the last 10 years, a large interest has developed in the preparation of nanocomposite structures by embedding inorganic nanoparticles into polymeric materials. These materials combine the properties of the inorganic fillers with the processability and flexibility of polymers. The versatility of polymer nanocomposite systems is of special interest to the gas sensor industry where arrays of polymer/carbon black composites have been used to identify gases and odours. These polymer gas sensors provide selectivity based on their chemical structures and operate at room temperature, which provide advantages over thick-film metal oxide gas sensors. ZnFe 2O 4 and ZnO have excellent stability, high sensitivity, low fabrication complexity and moderate operating temperatures, which are ideal properties for a gas sensing material. In this work, the development of a thick-film ZnFe 2O 4/ZnO sensor, which operates at room temperature and a drop-coated conducting polymer composite sensor containing 30 w/w% ZnFe 2O 4/ZnO nanoparticles is discussed. The sensors were tested in a fully automated test rig and showed promising results for the detection of alcohol vapours.

  3. A facile method for the preparation of bifunctional Mn:ZnS/ZnS/Fe3O4 magnetic and fluorescent nanocrystals

    PubMed Central

    Labiadh, Houcine; Ben Chaabane, Tahar; Sibille, Romain; Balan, Lavinia

    2015-01-01

    Summary Bifunctional magnetic and fluorescent core/shell/shell Mn:ZnS/ZnS/Fe3O4 nanocrystals were synthesized in a basic aqueous solution using 3-mercaptopropionic acid (MPA) as a capping ligand. The structural and optical properties of the heterostructures were characterized by X-ray diffraction (XRD), dynamic light scattering (DLS), transmission electron microscopy (TEM), UV–vis spectroscopy and photoluminescence (PL) spectroscopy. The PL spectra of Mn:ZnS/ZnS/Fe3O4 quantum dots (QDs) showed marked visible emission around 584 nm related to the 4T1 → 6A1 Mn2+ transition. The PL quantum yield (QY) and the remnant magnetization can be regulated by varying the thickness of the magnetic shell. The results showed that an increase in the thickness of the Fe3O4 magnetite layer around the Mn:ZnS/ZnS core reduced the PL QY but improved the magnetic properties of the composites. Nevertheless, a good compromise was achieved in order to maintain the dual modality of the nanocrystals, which may be promising candidates for various biological applications. PMID:26425426

  4. (Fe,Si,Al)-based nanocrystalline soft magnetic alloys for cryogenic applications

    NASA Astrophysics Data System (ADS)

    Daniil, Maria; Osofsky, Michael S.; Gubser, Donald U.; Willard, Matthew A.

    2010-04-01

    In this work Al and Si are substituted for Fe in a (Fe,Si,Al)-Nb-B-Cu alloy with the goal of improving its magnetic properties at 77 K. The x-ray diffraction patterns for a series of five alloys annealed at 823 K shows a Fe3(Si,Al) ordered phase with some residual amorphous phase. The lowest coercivity at room temperature was observed for the alloy with composition Fe68Si15.5Al3.5Nb3B9Cu1. At cryogenic temperatures, the saturation magnetization of 99.3 A m2/kg, coercivity of 0.45 A/m, and resistivity of 122 μΩ cm for the Fe63Si17.5Al6Nb3B9Cu1 alloy, compare favorably to commercial alloys at 77 K.

  5. Study of Al impurity induced magnetic instability in CeFe{sub 2}

    SciTech Connect

    Das, Rakesh; Srivastava, S. K.

    2015-05-15

    We report experimental and computational studies on Al impurity induced magnetic instabilities in CeFe{sub 2}. The work is based on the reported first order magneto-structural phase transition in Ce(Fe{sub 1-x}Al{sub x}){sub 2}, with 0.02 ≤ x ≤ 0.08, below 90 K. We performed first-principles calculations of electronic and magnetic properties of Ce(Fe{sub 1-x}Al{sub x}){sub 2} for x = 0.031 and 0.25. A concentration dependence of Fe and Ce moments is observed, while the Al impurity does not carry any appreciable moment in either case. We investigated spin-polarised partial density of states of Ce(Fe{sub 1-x}Al{sub x}){sub 2} and their various hybridizations in order to find an answer for an antiferromagnetic kind of order at low temperatures.

  6. A sessile drop setup for the time-resolved synchrotron study of solid-liquid interactions: Application to intermetallic formation in 55%Al-Zn alloys

    SciTech Connect

    Bernier, N. De Bruyn, D.; De Craene, M.; Scheers, J.; Claessens, S.; Vaughan, G. B. M.; Vitoux, H.; Gleyzolle, H.; Gorges, B.

    2014-04-28

    We introduce a dedicated setup for measuring by synchrotron diffraction in-situ crystallographic and chemical information at the solid–liquid interface. This setup mostly consists of a double-heating furnace composed of a resistive heating for the solid surface and an inductive heating to produce a liquid droplet. The available high energy and high flux beams allow the rapid reaction kinetics to be investigated with very good time resolution down to 1 ms. An application of this setup is illustrated for the growth mechanisms of intermetallic phases during the hot-dipping of steel in a 55%Al-Zn bath. Results show that the three η-Al{sub 5}Fe{sub 2}, θ-Al{sub 13}Fe{sub 4}, and α-Al{sub 8}Fe{sub 2}Si phases grow at different times and rates during the dipping process, whereas the face-centered cubic AlFe{sub 3} phase is not formed.

  7. Ferromagnetism and suppression of metallic clusters in Fe implanted ZnO -- a phenomenon related to defects?

    SciTech Connect

    Arenholz, Elke; Zhou, S.; Potzger, K.; Talut, G.; Reuther, H.; Kuepper, K.; Grenzer, J.; Xu, Q.; Mucklich, A.; Helm, M.; Fassbender, J.; Arenholz, E.

    2008-03-12

    We investigated ZnO(0001) single crystals annealed in high vacuum with respect to their magnetic properties and cluster formation tendency after implant-doping with Fe. While metallic Fe cluster formation is suppressed, no evidence for the relevance of the Fe magnetic moment to the observed ferromagnetism was found. The latter along with the cluster suppression is discussed with respect to defects in the ZnO host matrix, since the crystalline quality of the substrates was lowered due to the preparation as observed by x-ray diffraction.

  8. Catalytic conversion of syngas to mixed alcohols over Zn-Mn promoted Cu-Fe based catalyst

    DOE PAGESBeta

    Lu, Yongwu; Yu, Fei; Hu, Jin; Liu, Jian

    2012-04-12

    Zn-Mn promoted Cu-Fe based catalyst was synthesized by the co-precipitation method. Mixed alcohols synthesis from syngas was studied in a half-inch tubular reactor system after the catalyst was reduced. Zn-Mn promoted Cu-Fe based catalyst was characterized by SEM-EDS, TEM, XRD, and XPS. The liquid phase products (alcohol phase and hydrocarbon phase) were analyzed by GC-MS and the gas phase products were analyzed by GC. The results showed that Zn-Mn promoted Cu-Fe based catalyst had high catalytic activity and high alcohol selectivity. The maximal CO conversion rate was 72%, and the yield of alcohol and hydrocarbons were also very high. Cumore » (111) was the active site for mixed alcohols synthesis, Fe2C (101) was the active site for olefin and paraffin synthesis. The reaction mechanism of mixed alcohols synthesis from syngas over Zn-Mn promoted Cu-Fe based catalyst was proposed. Here, Zn-Mn promoted Cu-Fe based catalyst can be regarded as a potential candidate for catalytic conversion of biomass-derived syngas to mixed alcohols.« less

  9. Catalytic conversion of syngas to mixed alcohols over Zn-Mn promoted Cu-Fe based catalyst

    SciTech Connect

    Lu, Yongwu; Yu, Fei; Hu, Jin; Liu, Jian

    2012-04-12

    Zn-Mn promoted Cu-Fe based catalyst was synthesized by the co-precipitation method. Mixed alcohols synthesis from syngas was studied in a half-inch tubular reactor system after the catalyst was reduced. Zn-Mn promoted Cu-Fe based catalyst was characterized by SEM-EDS, TEM, XRD, and XPS. The liquid phase products (alcohol phase and hydrocarbon phase) were analyzed by GC-MS and the gas phase products were analyzed by GC. The results showed that Zn-Mn promoted Cu-Fe based catalyst had high catalytic activity and high alcohol selectivity. The maximal CO conversion rate was 72%, and the yield of alcohol and hydrocarbons were also very high. Cu (111) was the active site for mixed alcohols synthesis, Fe2C (101) was the active site for olefin and paraffin synthesis. The reaction mechanism of mixed alcohols synthesis from syngas over Zn-Mn promoted Cu-Fe based catalyst was proposed. Here, Zn-Mn promoted Cu-Fe based catalyst can be regarded as a potential candidate for catalytic conversion of biomass-derived syngas to mixed alcohols.

  10. High pressure studies of A2Mo3O12 negative thermal expansion materials (A2=Al2, Fe2, FeAl, AlGa)

    NASA Astrophysics Data System (ADS)

    Young, Lindsay; Gadient, Jennifer; Gao, Xiaodong; Lind, Cora

    2016-05-01

    High pressure powder X-ray diffraction studies of several A2Mo3O12 materials (A2=Al2, Fe2, FeAl, and AlGa) were conducted up to 6-7 GPa. All materials adopted a monoclinic structure under ambient conditions, and displayed similar phase transition behavior upon compression. The initial isotropic compressibility first became anisotropic, followed by a small but distinct drop in cell volume. These patterns could be described by a distorted variant of the ambient pressure polymorph. At higher pressures, a distinct high pressure phase formed. Indexing results confirmed that all materials adopted the same high pressure phase. All changes were reversible on decompression, although some hysteresis was observed. The similarity of the high pressure cells to previously reported Ga2Mo3O12 suggested that this material undergoes the same sequence of transitions as all materials investigated in this paper. It was found that the transition pressures for all phase changes increased with decreasing radius of the A-site cations.

  11. Synthesis of FeNi3/(Ni0.5Zn0.5)Fe2O4 nanocomposite and its high frequency complex permeability

    NASA Astrophysics Data System (ADS)

    Lu, Xuegang; Liang, Gongying; Zhang, Yumei; Zhang, Wei

    2007-01-01

    FeNi3/(Ni0.5Zn0.5)Fe2O4 nanocomposite particles were successfully synthesized using the hydrazine reduction combined with ammonia co-precipitation ferrite coating method. The x-ray and transmission electron microscopy analysis showed that face-centred cubic-structured FeNi3 nanoparticles were coated with spinel Ni-Zn ferrite. The composite particles were nearly spherical with diameters of about 80-200 nm and exhibited typical soft magnetic properties. The saturation magnetization (Ms) of the composite was greatly improved, compared with that of traditional ferrite. With increasing ferrite content, the eddy-current loss was effectively suppressed and a notable high frequency characteristic, in which the real part μ' of the permeability was almost independent of the frequency, was observed. The imaginary part μ'' remained at an extremely low value below the frequency of 300 MHz. The cut-off frequency fr was estimated to be above 1 GHz. The highest value of μ' reached 13 when the ratio of FeNi3 to Ni0.5Zn0.5Fe2O4 was 1:1. Two peaks were observed in the permeability spectra, which may be ascribed to the ferromagnetic resonances of FeNi3 and Ni-Zn ferrite respectively.

  12. Thermodynamic analysis of compatibility of several reinforcement materials with FeAl alloys

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.

    1988-01-01

    Chemical compatibility of several reinforcement materials with FeAl alloys within the concentration range 40 to 50 at pct Al have been analyzed from thermodynamic considerations at 1173 and 1273 K. The reinforcement materials considered in this study include carbides, borides, oxides, nitrides, and silicides. Although several chemically compatible reinforcement materials are identified, the coefficients of thermal expansion for none of these materials match closely with that of FeAl alloys and this might pose serious problems in the design of composite systems based on FeAl alloys.

  13. Third element effect in the surface zone of Fe-Cr-Al alloys

    NASA Astrophysics Data System (ADS)

    Airiskallio, E.; Nurmi, E.; Heinonen, M. H.; Väyrynen, I. J.; Kokko, K.; Ropo, M.; Punkkinen, M. P. J.; Pitkänen, H.; Alatalo, M.; Kollár, J.; Johansson, B.; Vitos, L.

    2010-01-01

    The third element effect to improve the high temperature corrosion resistance of the low-Al Fe-Cr-Al alloys is suggested to involve a mechanism that boosts the recovering of the Al concentration to the required level in the Al-depleted zone beneath the oxide layer. We propose that the key factor in this mechanism is the coexistent Cr depletion that helps to maintain a sufficient Al content in the depleted zone. Several previous experiments related to our study support that conditions for such a mechanism to be functional prevail in real oxidation processes of Fe-Cr-Al alloys.

  14. Structural disorder and magnetism in the spin-gapless semiconductor CoFeCrAl

    NASA Astrophysics Data System (ADS)

    Choudhary, Renu; Kharel, Parashu; Valloppilly, Shah R.; Jin, Yunlong; O'Connell, Andrew; Huh, Yung; Gilbert, Simeon; Kashyap, Arti; Sellmyer, D. J.; Skomski, Ralph

    2016-05-01

    Disordered CoFeCrAl and CoFeCrSi0.5Al0.5 alloys have been investigated experimentally and by first-principle calculations. The melt-spun and annealed samples all exhibit Heusler-type superlattice peaks, but the peak intensities indicate a substantial degree of B2-type chemical disorder. Si substitution reduces the degree of this disorder. Our theoretical analysis also considers several types of antisite disorder (Fe-Co, Fe-Cr, Co-Cr) in Y-ordered CoFeCrAl and partial substitution of Si for Al. The substitution transforms the spin-gapless semiconductor CoFeCrAl into a half-metallic ferrimagnet and increases the half-metallic band gap by 0.12 eV. Compared CoFeCrAl, the moment of CoFeCrSi0.5Al0.5 is predicted to increase from 2.01 μB to 2.50 μB per formula unit, in good agreement with experiment.

  15. A simple route to synthesize ZnFe2O4 hollow spheres and their magnetorheological characteristics

    NASA Astrophysics Data System (ADS)

    Jiang, Wanquan; Cao, Zhen; Gu, Rui; Ye, Xingzhu; Jiang, Cuifeng; Gong, Xinglong

    2009-12-01

    In this paper, a simple route to synthesize hollow spheres of ZnFe2O4 without the assistance of a template is reported. The crystal structure and morphology of these particles were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FE-SEM). It was found that the final products were hollow spheres with perfect morphology, and their size and the thickness of their shells decreased with the increase of urea precursor. Ferromagnetism was observed from the magnetic hysteresis loops of the ZnFe2O4 hollow spheres at room temperature. The possible formation mechanism of the hollow spheres is discussed. In addition, ZnFe2O4 magnetorheological (MR) fluids were prepared and then their MR effect was investigated on a rotational rheometer equipped with a magnetic field generator.

  16. Donnan membrane speciation of Al, Fe, trace metals and REEs in coastal lowland acid sulfate soil-impacted drainage waters.

    PubMed

    Jones, Adele M; Xue, Youjia; Kinsela, Andrew S; Wilcken, Klaus M; Collins, Richard N

    2016-03-15

    Donnan dialysis has been applied to forty filtered drainage waters collected from five coastal lowland acid sulfate soil (CLASS) catchments across north-eastern NSW, Australia. Despite having average pH values<3.9, 78 and 58% of Al and total Fe, respectively, were present as neutral or negatively-charged species. Complementary isotope dilution experiments with (55)Fe and (26)Al demonstrated that only soluble (i.e. no colloidal) species were present. Trivalent rare earth elements (REEs) were also mainly present (>70%) as negatively-charged complexes. In contrast, the speciation of the divalent trace metals Co, Mn, Ni and Zn was dominated by positively-charged complexes and was strongly correlated with the alkaline earth metals Ca and Mg. Thermodynamic equilibrium speciation calculations indicated that natural organic matter (NOM) complexes dominated Fe(III) speciation in agreement with that obtained by Donnan dialysis. In the case of Fe(II), however, the free cation was predicted to dominate under thermodynamic equilibrium, whilst our results indicated that Fe(II) was mainly present as neutral or negatively-charged complexes (most likely with sulfate). For all other divalent metals thermodynamic equilibrium speciation calculations agreed well with the Donnan dialysis results. The proportion of Al and REEs predicted to be negatively-charged was also grossly underestimated, relative to the experimental results, highlighting possible inaccuracies in the stability constants developed for these trivalent Me(SO4)2(-) and/or Me-NOM complexes and difficulties in modeling complex environmental samples. These results will help improve metal mobility and toxicity models developed for CLASS-affected environments, and also demonstrate that Australian CLASS environments can discharge REEs at concentrations an order of magnitude greater than previously reported. PMID:26780135

  17. High strain-rate plastic flow in Fe and Al

    NASA Astrophysics Data System (ADS)

    Smith, Raymond; Eggert, Jon; Rudd, Robert; Bolme, Cynthia; Collins, Gilbert

    2011-06-01

    Understanding the nature and time-dependence of material deformation at high strain rates is an important goal in condensed matter physics. Under dynamic loading, the rate of plastic strain is determined by the flow of dislocations through the crystal lattice and is a complex function of time, distance, sample purity, temperature, internal stresses, microstructure and strain rate. Under shock compression time-dependent plasticity is typically inferred by fitting elastic precursor stresses as a function of propagation distance with a phenomenologically based dislocation kinetics model. We employ a laser-driven ramp wave loading technique to compress 6-70 micron thick samples of bcc-Fe and fcc-Al over a strain rate range of 1e6-1e8 1/s. Our data show that for fixed sample thickness, stresses associated the onset of plasticity are highly dependent on the strain rate of compression and do not readily fit into the elastic stress - distance evolution descriptive of instantaneous shock loading. We find that the elastic stress at the onset of plasticity is well correlated with the strain rate at the onset of plastic flow for both shock- and ramp-wave experiments. Our data, combined with data from other dynamic compression platforms, reveal a sharp increase in the peak elastic stress at high strain rates, consistent with a transition in dislocation flow dominated by phonon drag. smith248@llnl.gov

  18. Multiple diffraction in an icosahedral Al-Cu-Fe quasicrystal

    NASA Astrophysics Data System (ADS)

    Fan, C. Z.; Weber, Th.; Deloudi, S.; Steurer, W.

    2011-07-01

    In order to reveal its influence on quasicrystal structure analysis, multiple diffraction (MD) effects in an icosahedral Al-Cu-Fe quasicrystal have been investigated in-house on an Oxford Diffraction four-circle diffractometer equipped with an Onyx™ CCD area detector and MoKα radiation. For that purpose, an automated approach for Renninger scans (ψ-scans) has been developed. Two weak reflections were chosen as the main reflections (called P) in the present measurements. As is well known for periodic crystals, it is also observed for this quasicrystal that the intensity of the main reflection may significantly increase if the simultaneous (H) and the coupling (P-H) reflections are both strong, while there is no obvious MD effect if one of them is weak. The occurrence of MD events during ψ-scans has been studied based on an ideal structure model and the kinematical MD theory. The reliability of the approach is revealed by the good agreement between simulation and experiment. It shows that the multiple diffraction effect is quite significant.

  19. Machining of Fe[sub 3]Al intermetallics

    SciTech Connect

    Woodyard, J.R.

    1992-01-01

    Scientists at the US Bureau of Mines are studying iron aluminides as possible substitutes for stainless steels to reduce the Nation's dependence on imported strategic and critical materials. In a Bureau investigation on the mechanical properties of Fe-28Al, it was found that the material's machining properties were significantly improved at slow tool and feed speeds. Machining techniques normally used for brittle materials failed or were costly. Further experiments using a 5-in (12.7-cm) mill cutter with carbide inserts, operating dry at minimum machining speeds, produced visually smooth sample surfaces with no tool damage. As a result of these experiments and a review of published data on hydrogen embrittlement of iron aluminide under tension, non-water-based (e.g., sulfur-based) lubricants were chosen for production machining. Four-flute, 3/4-in(19-mm) carbide end mills were used at slow speed under lubrication. This latter procedure reduced tool wear and breakage by a factor of 2. Machined surfaces and specimen cross sections were analyzed by scanning electron microscopy to detect microcracking. Tensile tests gave the expected yield and ultimate strengths, indicating that no degradation by low-speed machining occurred. This study extends this work to show that the alloy can be machined at higher speeds using high-speed steel end mills, and that water-soluble cutting oil is a suitable lubricant and coolant. 11 figs., 1 tab.

  20. Transparent conductive Al-doped ZnO thin films grown at room temperature

    SciTech Connect

    Wang Yuping; Lu Jianguo; Bie Xun; Gong Li; Li Xiang; Song Da; Zhao Xuyang; Ye Wenyi; Ye Zhizhen

    2011-05-15

    Aluminum-doped ZnO (ZnO:Al, AZO) thin films were prepared on glass substrates by dc reactive magnetron sputtering from a Zn-Al alloy target at room temperature. The effects of the Ar-to-O{sub 2} partial pressure ratios on the structural, electrical, and optical properties of AZO films were studied in detail. AZO films grown using 100:4 to 100:8 Ar-to-O{sub 2} ratio result in acceptable quality films with c-axis orientated crystals, uniform grains, 10{sup -3} {Omega} cm resistivity, greater than 10{sup 20} cm{sup -3} electron concentration, and high transmittance, 90%, in the visible region. The lowest resistivity of 4.11x10{sup -3} {Omega} cm was obtained under the Ar-to-O{sub 2} partial pressure ratio of 100:4. A relatively strong UV emission at {approx}3.26 eV was observed in the room-temperature photoluminescence spectrum. X-ray photoelectron spectroscopy analysis confirmed that Al was introduced into ZnO and substitutes for Zn and doped the film n-type.

  1. Large lateral photovoltaic effect observed in nano Al-doped ZnO films

    NASA Astrophysics Data System (ADS)

    Lu, Jing; Wang, Hui

    2011-07-01

    Zinc oxide (ZnO), including a variety of metal-doped ZnO, as one kind of most important photoelectric materials, has been widely investigated and received enormous attention for a series of applications. In this work, we report a new finding which we call as lateral photovoltaic effect (LPE) in a nano Al-doped ZnO (ZAO) film based on ZAO/SiO2/Si homo-heterostructure. This large and stable LPE observed in ZAO is an important supplement to the existing ZnO properties. In addition, all data and analyses demonstrate ZAO film can also be a good candidate for new type position-sensitive detector (PSD) devices.

  2. The effect of non-magnetic Al3+ ions on the structure and electromagnetic properties of MgCuZn ferrite

    NASA Astrophysics Data System (ADS)

    Bahiraei, Hamed; Shoushtari, Morteza Zargar; Gheisari, Khalil; Ong, C. K.

    2014-12-01

    A series of Al substituted MgCuZn ferrite powders with composition Mg0.3Cu0.2Zn0.52AlxFe1.98-xO3.99 (0.00≤x≤0.06) have been synthesized with nano-sized precursor powders through the nitrate-citrate auto-combustion route. These powders were calcined, compacted and sintered at 900 °C for 4 h. X-ray diffraction patterns show the formation of cubic spinel structure. Infrared spectra indicate two fundamental absorption bands corresponding to the tetrahedral and octahedral complexes, respectively. A significant increase in density and grain size is observed with increasing Al content. The room temperature saturation magnetization increases for x=0.015 and then decreases for further increase in Al substitution. The initial permeability increases with the Al content attributed to the increase in the grain size and density. Curie temperature is found to be dependent on the Al concentration and it decreases due to decrease in the number of super-exchange interactions between Fe3+ ions in the tetrahedral and octahedral sites.

  3. Resistive switching characteristics of a compact ZnO nanorod array grown directly on an Al-doped ZnO substrate

    NASA Astrophysics Data System (ADS)

    Yoo, E. J.; Shin, J. Y.; Yoon, T. S.; Kang, C. J.; Choi, Y. J.

    2016-07-01

    ZnO’s resistive switching properties have drawn much attention because ZnO has a simple chemical composition and is easy to manipulate. The propulsion mechanism for resistive switching in ZnO is based on a conducting filament that consists of oxygen vacancies. In the case of film structure, the random formation of the conducting filaments occasionally leads to unstable switching characteristics. Limiting the direction in which the conducting filaments are formed is one way to solve this problem. In this study, we demonstrate reliable resistive switching behavior in a device with an Au/compact ZnO nanorod array/Al-doped ZnO structure with stable resistive switching over 105 cycles and a long retention time of 104 s by confining conducting filaments along the boundaries between ZnO nanorods. The restrictive formation of conducting filaments along the boundaries between ZnO nanorods is observed directly using conductive atomic force microscopy.

  4. Synthesis and characterization of Fe3O4 and ZnO nanocomposites by the sol-gelmethod

    NASA Astrophysics Data System (ADS)

    Hasanpour, A.; Niyaifar, M.; Asan, M.; Amighian, J.

    2013-05-01

    In this work, magnetite (Fe3O4) nanoparticles were first prepared from ferric nitrate (Fe(NO3)3 9H2O) and ethylene glycol (C2H6O2) in inert atmosphere using the sol-gel method. In the next stage, composite nanopowders of Fe3O4-ZnO were obtained from zinc acetate and diethanolamine via the sol-gel method. The precursor was first dried and then annealed in vacuum furnace at different temperatures. The X-ray diffraction results confirm the formation of Fe3O4-ZnO nanocomposites. Transmission Electron Microscopy showed that the prepared powders are made of the spherical shape particles with an average size of about 40 nm. Fourier transform infrared spectra for the characteristic absorption of Zn-O bond is at 453.1 cm-1and of Fe-O bond is 540.2 cm-1. Results of vibrating sample magnetometer reveal that the Fe3O4 nanoparticles are superparamagnetic, whereas in the form of Fe3O4-ZnO nanocomposites arenot.

  5. Tailoring Energy Bandgap of Al Doped ZnO Thin Films Grown by Vacuum Thermal Evaporation Method.

    PubMed

    Vyas, Sumit; Singh, Shaivalini; Chakrabarti, P

    2015-12-01

    The paper presents the results of our experimental investigation pertaining to tailoring of energy bandgap and other associated characteristics of undoped and Al doped ZnO (AZO) thin film by varying the atomic concentration of Al in ZnO. Thin films of ZnO and ZnO doped with Al (1, 3, and 5 atomic percent (at.%)) were deposited on silicon substrate for structural characterization and on glass substrate for optical characterization. The dependence of structural and optical properties of Al doped ZnO on the atomic concentration of Al added to ZnO has been reported. On the basis of the experimental results an empirical formula has been proposed to calculate the energy bandgap of AZO theoretically in the range of 1 to 5 at.% of Al. The study revealed that AZO films are composed of smaller and larger number of grains as compared to pure ZnO counterpart and density of the grains was found to increase as the Al concentration increased (from 1 to 5 at.%). The transmittance in the visible region was greater than 90% and found to increase with increasing Al concentration up to 5 at.%. The optical bandgap was found to increase initially with increase in atomic concentration of Al concentration up to 3 at.% and decrease thereafter with increasing concentration of Al. PMID:26682390

  6. Interpretation of ferromagnetic Fe doped ZnO by Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Park, Seung-Iel; Ahn, Geun Young; Kim, Chul Sung

    2007-05-01

    Single phase Zn0.95Fe0.05O sample was obtained by the sol-gel method with annealing at 650°C for 6h in H2 5%/Ar balance gas atmosphere. The crystalline structure of Zn0.95Fe0.05O is determined to be a P63mc hexagonal structure with lattice constants a0=3.255Å and c0=5.207Å at room temperature. The Mössbauer spectra were obtained at various temperatures ranging from 4.2to295K. The values of the isomer shifts (δ ) show that for all temperature ranges, they are in the ferrous (Fe2+) state. The magnetic hyperfine field (Hhf) and electric quadrupole splitting (ΔEQ) in the weak ferromagnetic state at 4.2K have been analyzed, yielding the following results: Hhf=37.8kOe, θ =67.5°, φ =0°, η =0.75, ΔEQ=2.06mm /s, and R =7.4, respectively. From the Mössbauer spectrum at 77K, the paramagnetic quadrupole phase is related to the temperature dependence of spin-lattice relaxation.

  7. Defects induced magnetization in B-doped ZnFeO dilute magnetic semiconductors

    NASA Astrophysics Data System (ADS)

    Saleem, Murtaza; Sabieh Anwar, M.; Mahmood, Asif; Atiq, Shahid; Ramay, Shahid M.; Siddiqi, Saadat A.

    2015-05-01

    Zn0.95-xFe0.05BxO (x=0, 0.05) nano-particles have been synthesized using a modified chemically derived citrate gel method. X-ray diffraction analysis demonstrates the wurtzite type hexagonal structure belonging to P63mc space group without the presence of any secondary phase in both compositions. The Diffraction analysis shows that Fe2+ and B3+ ions have replaced some of the Zn2+ ions while some occupy un-detectable interstitial and inter-granular positions inside the structure. Scanning electron micrographs obtained using scanning electron microscopy show typical smaller size of particles in B-doped composition. Temperature dependent electrical resistivity analysis shows the semiconducting characteristics of the compositions and that doping of Fe and B up to 10 at% does not change the electrical behavior of the host material. Magnetic measurements display room temperature ferromagnetism in both compositions with enhanced magnetization in B-doped composition associated with defect induced magnetic mechanism belonging to intrinsically augmented interstitial and inter-granular effects.

  8. Thermoelectric properties optimization of Al-doped ZnO thin films prepared by reactive sputtering Zn-Al alloy target

    NASA Astrophysics Data System (ADS)

    Fan, Ping; Li, Ying-zhen; Zheng, Zhuang-hao; Lin, Qing-yun; Luo, Jing-ting; Liang, Guang-xing; Zhang, Miao-qin; Chen, Min-cong

    2013-11-01

    Al-doped ZnO (AZO) has practical applications in the industry for thermoelectric generation, owing to its nontoxicity, low-cost and stability at high temperatures. In this study, AZO thin films with high quality were deposited on BK7 glass substrates at room-temperature by direct current reactive magnetron sputtering using Zn-Al alloy target. The deposited thin films were annealed at various temperatures ranging from 623 K to 823 K with a space of 50 K. It is found that the absolute value of Seebeck coefficient of AZO thin film annealed at 723 K increases stably with increasing of measuring temperature and reaches a value of ∼60 μV/K at 575 K. After that, Al-doping content was varied to further optimize the thermoelectric properties of AZO thin films. The power factor of AZO thin films with Al content of 3 wt% increased with increase of measuring temperature and the maximum power factor of 1.54 × 10-4 W m-1K-2 was obtained at 550 K with the maximum absolute values of Seebeck coefficient of 99 μV/K, which is promising for high temperature thermoelectric application.

  9. Comparative X-ray diffraction and infrared spectroscopy study of Zn-Al layered double hydroxides: Vanadate vs nitrate

    NASA Astrophysics Data System (ADS)

    Salak, Andrei N.; Tedim, João; Kuznetsova, Alena I.; Ribeiro, José L.; Vieira, Luís G.; Zheludkevich, Mikhail L.; Ferreira, Mário G. S.

    2012-03-01

    Zn-Al layered double hydroxides (LDH) are promising as nanocontainers of corrosion inhibitors in self-healing corrosion protection coatings. Zn(2)Al-vanadate (Zn/Al = 2:1) is prepared by anion exchange from the parent composition Zn(2)Al-nitrate at pH ˜ 8. Crystal structure and vibrational spectra of both LDHs have been studied in comparison. Their interlayer distances are rather larger than those corresponding to the most compact arrangement of the intercalated anions. Nevertheless, no sign of a turbostratic disorder has been detected in these LDH. Based on the analysis of the spectroscopic data in combination with the XRD results, it has been shown that vanadate anion, which substitutes nitrate at the anion exchange, is pyrovanadate, VO74-. The observed disorder in the hydroxide layers in Zn(2)Al-V2O7 is likely to result from strong interactions between V5+ and Zn2+/Al3. Although Zn(2)Al-NO3 is less disordered than Zn(2)Al-V2O7, it exhibits no long-range order in arrangement of cations in the hydroxide layers.

  10. Erosion studies on a Fe sub 3 Al-based iron aluminide and 1100 Al

    SciTech Connect

    Rao, M.; Keiser, J.

    1991-01-01

    Samples of a Fe{sub 3}Al-based iron aluminide alloy were eroded using nominally spherical steel shot. Two distinct erosion mechanisms were observed: (1) extrusion of platelets resulting from spherical particle impacts and (2) cutting of the target by angular particles either present in the initial erodent or formed on impact by fracture of the shot. The overall erosion resistance of the alloy was judged to be relatively good and may be improved by increasing the alloy's ductility. Measurements using a mechanical properties microprobe (MPM) showed that significant work hardening occurred due to erosion, but the hardness dropped off near the surface, apparently due to thermal effects. In contrast no sub-surface softening was observed in samples of 1100 Al which were also eroded by steel shot. In order to model the impact process, single 343 {mu}m WC spheres were shot at the two alloys at velocities between 20 m/s and 900 m/s. Compared to the iron aluminide, the craters on 1100 Al show better developed lips and features indicative of sustained plastic deformation. Both alloys showed thermally induced subsurface softening at high velocities. At lower velocities, only the iron aluminide showed clear thermal effects. Results of the single particle and multiple particle impact tests are reconciled in terms of deformation behavior and thermal effects. 22 refs., 7 figs.

  11. Activities of the components in a spinel solid solution of the Fe-Al-O system

    NASA Astrophysics Data System (ADS)

    Lykasov, A. A.; Kimyashev, A. A.

    2011-09-01

    The conditions of the equilibrium between the Fe3O4-FeAl2O4 solution and wustite are determined by measuring the EMF of galvanic cells containing a solid electrolyte, and the activities of the components in the Fe3O4-FeAl2O4 solution are calculated by treating the results of the experiment on the equilibrium between the spinel solution and wustite. Their properties are found to be different from those of ideal solutions at temperatures of 1000-1300 K. A significant positive deviation from the Raoult's law is believed to indicate the tendency of the solution to decompose. The experimental data are treated in terms of the theory of regular solutions, assuming the energy of mixing to be a function of temperature only. The critical temperature of decomposition for the Fe3O4-FeAl2O4 solution is found to be 1084 K.

  12. Effect of substrate temperature on the structural and optical properties of ZnO and Al-doped ZnO thin films prepared by dc magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Li, Xue-Yong; Li, Hong-Jian; Wang, Zhi-Jun; Xia, Hui; Xiong, Zhi-Yong; Wang, Jun-Xi; Yang, Bing-Chu

    2009-01-01

    ZnO and Al-doped ZnO(ZAO) thin films have been prepared on glass substrates by direct current (dc) magnetron sputtering from 99.99% pure Zn metallic and ZnO:3 wt%Al 2O 3 ceramic targets, the effects of substrate temperature on the crystallization behavior and optical properties of the films have been studied. It shows that the surface morphologies of ZAO films exhibit difference from that of ZnO films, while their preferential crystalline growth orientation revealed by X-ray diffraction remains always the (0 0 2). The optical transmittance and photoluminescence (PL) spectra of both ZnO and ZAO films are obviously influenced by the substrate temperature. All films exhibit a transmittance higher than 86% in the visible region, while the optical transmittance of ZAO films is slightly smaller than that of ZnO films. More significantly, Al-doping leads to a larger optical band gap ( Eg) of the films. It is found from the PL measurement that near-band-edge (NBE) emission and deep-level (DL) emission are observed in pure ZnO thin films. However, when Al was doped into thin films, the DL emission of the thin films is depressed. As the substrate temperature increases, the peak of NBE emission has a blueshift to region of higher photon energy, which shows a trend similar to the Eg in optical transmittance measurement.

  13. Electronic structure and magnetism on FeSiAl alloy: A DFT study

    NASA Astrophysics Data System (ADS)

    Cardoso Schwindt, V.; Sandoval, M.; Ardenghi, J. S.; Bechthold, P.; González, E. A.; Jasen, P. V.

    2015-09-01

    Density functional theory (DFT) calculation has been performed to study the electronic structure and chemical bonding in FeSiAl alloy. These calculations are useful to understand the magnetic properties of this alloy. Our results show that the mean magnetic moment of Fe atoms decreases due to the crystal structure and the effect of Si and Al. Depending on the environment, the magnetic moment of one Fe site (Fe1) increases to about 14.3% while of the other site (Fe2) decreases to about 25.9% (compared with pure bcc Fe). All metal-metal overlap interactions are bonding and slightly weaker than those found in the bcc Fe structure. The electronic structure (DOS) shows an important hybridization among Fe, Si and Al atoms, thus making asymmetric the PDOS with a very slight polarization of Al and Si atoms. Our study explains the importance of crystal structure in determining the magnetic properties of the alloys. FeSiAl is a good candidate for electromagnetic interference shielding combining low price and good mechanical and magnetic properties.

  14. Carriers-mediated ferromagnetic enhancement in Al-doped ZnMnO dilute magnetic semiconductors

    SciTech Connect

    Saleem, Murtaza; Siddiqi, Saadat A.; Atiq, Shahid; Anwar, M. Sabieh; Hussain, Irshad; Alam, Shahzad

    2011-11-15

    Nano-crystalline Zn{sub 0.95-x}Mn{sub 0.05}Al{sub x}O (x = 0, 0.05, 0.10) dilute magnetic semiconductors (DMS) were synthesized by sol-gel derived auto-combustion. X-ray diffraction (XRD) analysis shows that the samples have pure wurtzite structure typical of ZnO without the formation of secondary phases or impurity. Crystallite sizes were approximated by Scherrer formula while surface morphology and grain sizes were measured by field emission scanning electron microscopy. Incorporation of Mn and Al into the ZnO structure was confirmed by energy-dispersive X-ray analysis. Temperature dependent electrical resistivity measurements showed a decreasing trend with the doping of Al in ZnMnO, which is attributable to the enhancement of free carriers. Vibrating sample magnetometer studies confirmed the presence of ferromagnetic behavior at room temperature. The results indicate that Al doping results in significant variation in the concentration of free carriers and correspondingly the carrier-mediated magnetization and room temperature ferromagnetic behavior, showing promise for practical applications. We attribute the enhanced saturation magnetization and electrical conductivity to the exchange interaction mediated by free electrons.

  15. Synthesis, structure and ESR studies of Mg doped ZnAlO nanoparticles

    NASA Astrophysics Data System (ADS)

    Cakiroglu, O.; Acikgoz, M.; Arda, L.; Akcan, D.; Dogan, N.

    2015-01-01

    Zn0.98-xMgxAl0.02O solutions with different (x=0.05, 0.10, 0.15, and 0.20) compositions were synthesized by the sol-gel technique using Zn, Mg and Al based alkoxide. The effects of highly Mg doping ratio on structure and magnetic properties were investigated systematically. The phase and the crystal structure of the Zn0.98-xMgxAl0.02O nanoparticles were characterized using X-ray diffraction. Scanning Electron Microscope and X-ray diffraction were utilized to understand the size and microstructure of samples. We observed the particle sizes of nanoparticles between 80 nm and 100 nm range. Furthermore, ESR spectra of Zn0.98-xMgxAl0.02O nanoparticles were collected at room temperature on a Bruker EMX model X-band spectrometer operating at a frequency of 9.50 GHz. It is observed that the critical concentration of Mg, x=0.1, has minimum g-factor and maximum line-width (W).

  16. Effects of hydrogen ambient and film thickness on ZnO:Al properties

    SciTech Connect

    Duenow, Joel N.; Gessert, Timothy A.; Wood, David M.; Dillon, Anne C.; Coutts, Timothy J.

    2008-07-15

    Undoped ZnO and ZnO:Al (0.1, 0.2, 0.5, 1.0, and 2.0 wt. % Al{sub 2}O{sub 3}) films were deposited by rf magnetron sputtering. Controlled incorporation of H{sub 2} in the Ar sputtering ambient for films grown at substrate temperatures up to 200 deg. C results in mobilities exceeding 50 cm{sup 2} V{sup -1} s{sup -1} when using targets containing 0.1 and 0.2 wt. % Al{sub 2}O{sub 3}. Temperature-dependent Hall measurements show evidence of phonon scattering as the dominant scattering mechanism in these lightly Al-doped films, while ionized impurity scattering appears increasingly dominant at higher doping levels. A combination of compositional and structural analysis shows that hydrogen expands the ZnO lattice normal to the plane of the substrate and desorbs from ZnO at {approx}250 deg. C according to temperature-programmed desorption and annealing experiments.

  17. Al-doped ZnO nanocoatings obtained by sol-gel route

    NASA Astrophysics Data System (ADS)

    Mihaiu, S.; Toader, A.; Atkinson, I.; Anastasescu, M.; Vasilescu, M.; Zaharescu, M.; Plugaru, R.

    2010-11-01

    In recent years aluminum doped zinc oxide (AZO) film has attracted more attention due to many advantages including low cost, non-toxicity, and high stability to H2 plasma in comparison with indium tin oxide (ITO) film, the best known and used transparent conductive oxide (TCO) film. In this work, mono and multilayer Al-doped ZnO coatings have been obtained by dip coating sol-gel method on the glass and silicon supports. X-ray Diffraction, Atomic Force Microscopy (AFM) and Fluorescence Spectroscopy were used for the structural, morphological and optical characterization of the obtained coatings. The multilayer Al-doped ZnO coatings (after five layer depositions) on the silicon substrate present a polycrystalline wurtzite type structure with crystallite size of 20 nm. The AFM measurements have shown that no matter the support type, the Al-doped ZnO coatings present a similar morphology consisting in a smooth distribution of the circular grains leading also to similar values of the RMS roughness, around 2 nm. The photoluminescence properties of the Al-doped ZnO coatings depend on the number of depositions and type of substrate. Systematic study performed allows finding most suitable parameters for obtaining coatings with desired properties.

  18. Enhanced GMI effect in NiZn-ferrite-modified Fe-based amorphous ribbons

    NASA Astrophysics Data System (ADS)

    Sun, Xiaojun; Du, Jinlu; Zhu, Zengtai; Wang, Jianbo; Liu, Qingfang

    2015-06-01

    A thin NiZn-ferrite layer was fabricated on the free surface of a Fe-based amorphous ribbon by radio frequency magnetron sputtering, and the giant magnetoimpedance (GMI) effect was measured at different magnetic fields and frequencies. An enhanced GMI effect has been observed in the NiZn-ferrite-modified ribbon at all measured frequencies. The largest GMI ratio up to 80 % is about 2.6 times as large as that of the ribbon without any coating. This enhanced GMI effect is mainly explained in terms of induced stress, the transformation of the domain structure and the magnetic flux path in the modified ribbon. The results obtained are of significant importance in developing strong-signal magnetic sensors.

  19. Point defect concentrations and solid solution hardening in NiAl with Fe additions

    SciTech Connect

    Pike, L.M.; Chang, Y.A.; Liu, C.T.

    1997-08-01

    The solid solution hardening behavior exhibited when Fe is added to NiAl is investigated. This is an interesting problem to consider since the ternary Fe additions may choose to occupy either the Ni or the Al sublattice, affecting the hardness at differing rates. Moreover, the addition of Fe may affect the concentrations of other point defects such as vacancies and Ni anti-sites. As a result, unusual effects ranging from rapid hardening to solid solution softening are observed. Alloys with varying amounts of Fe were prepared in Ni-rich (40 at. % Al) and stoichiometric (50 at. % Al) compositions. Vacancy concentrations were measured using lattice parameter and density measurements. The site occupancy of Fe was determined using ALCHEMI. Using these two techniques the site occupancies of all species could be uniquely determined. Significant differences in the defect concentrations as well as the hardening behavior were encountered between the Ni-rich and stoichiometric regimes.

  20. Structural and Thermal Study of Nanocrystalline Fe-Al-B Alloy Prepared by Mechanical Alloying

    NASA Astrophysics Data System (ADS)

    Gharsallah, Hana Ibn; Sekri, Abderrahmen; Azabou, Myriam; Escoda, Luiza; Suñol, Joan Josep; Khitouni, Mohamed

    2015-08-01

    Nanostructured iron-aluminum alloy of Fe-25 at. pct Al composition doped with 0.2 at. pct B was prepared by mechanical alloying. The phase transformations and structural changes occurring in the studied material during mechanical alloying and during subsequent heating were investigated by SEM, XRD, and DSC techniques. The patterns so obtained were analyzed using the Rietveld program. The alloyed powders were disordered Fe(Al) solid solutions and Fe2B boride phase. The Fe2B boride phase is formed after 4 hours of milling. The crystallite size reduction to the nanometer scale (5 to 8 nm) is accompanied by an increase in lattice strains. The powder milled for 40 hours was annealed at temperatures of 523 K, 823 K, 883 K, and 973 K (250 °C, 550 °C, 610 °C, and 700 °C) for 2 hours. Low temperatures annealing are responsible for the relaxation of the disordered structure, while high temperatures annealing enabled supersaturated Fe(Al) solid solutions to precipitate out fines Fe3Al, Fe2Al5, and Fe4Al13 intermetallics and, also the recrystallization and the grain growth phenomena.

  1. Preparation and Properties of a Novel Al-Si-Ge-Zn Filler Metal for Brazing Aluminum

    NASA Astrophysics Data System (ADS)

    Niu, Zhiwei; Huang, Jihua; Yang, Hao; Chen, Shuhai; Zhao, Xingke

    2015-06-01

    The study is concerned with developing a filler metal with low melting temperature and good processability for brazing aluminum and its alloys. For this purpose, a novel Al-Si-Ge-Zn alloy was prepared according to Al-Si-Ge and Al-Si-Zn ternary phase diagrams. The melting characteristics, microstructures, wettability, and processing property of the alloy were investigated. The results showed that the melting temperature range of the novel filler metal was 505.2-545.1 °C, and the temperature interval between the solidus and the liquidus was 39.9 °C. Compared with a common Al-Si-Ge alloy, it had smaller and better dispersed β-GeSi solid solution precipitates, and the Zn-rich phases distributed on the boundary of the β-GeSi precipitates. The novel filler metal has good processability and good wettability with Al. There was one obvious transition layer with a thin α-Al solid solution between the filler metal and base metal, which is favorable to improve the strength of brazing joint.

  2. An analytical electron microscopic investigation of precipitation in an Al-Cu-Zn-Mg-Ag alloy.

    PubMed

    Hasan, F; Lorimer, G W

    1993-03-01

    The distribution, morphology, chemistry, and crystallography of the precipitates formed during aging of an Al-Cu-Zn-Mg-Ag alloy have been studied using analytical transmission electron microscopy. The first precipitates to appear during aging at 150 degrees C were thin hexagonal-shaped plate-like precipitates which formed on the (111)Al planes. These precipitates had a face-centred orthorhombic crystal structure and their composition was essentially CuAl2 although they contained a trace of silver. At peak hardness the microstructure consisted of the plate-like precipitates on (111)Al planes and theta' precipitates on (100)Al planes. Overaging resulted in the precipitation of equilibrium theta, CuAl2, which exhibited a lath morphology and an orientation-relationship with the matrix (210)Al magnitude of (110)gamma; (001)Al misoriented from (001)gamma by approximately 6 degrees. Prolonged overaging at 250 degrees C resulted in the formation of cuboid-shaped Al5(Cu,Zn)6Mg2 precipitates which had a cubic crystal structure and a cube:cube orientation-relationship with the matrix. PMID:8513176

  3. Impurity Diffusion Coefficients of Al and Zn in Mg Determined from Solid-to-Solid Diffusion Couples

    SciTech Connect

    Kammerer, Catherine; Kulkarni, Nagraj S; Warmack, Robert J Bruce; Perry, Kelly A; Belova, Irina; Murch, Prof. Graeme; Sohn, Yong Ho

    2013-08-01

    Increasing use and development of lightweight Mgalloys have led to the desire for more fundamental research in and understanding of Mg-based systems. As property enhancing components, Al and Zn are two of the most important and common alloying elements for Mg-alloys. We have investigated the concentration dependent interdiffusion of Al and Zn in Mg using diffusion couples of pure polycrystalline Mg mated to Mg solid solutions containing either <9 at.% Al or <3 at.% Zn. Concentration profiles were determined by electron micro-probe microanalysis of the diffusion zone. The interdiffusion coefficients were determined by the classical Boltzmann-Matano method within the Mg solid solution. As the concentration of Al or Zn approaches the dilute ends, we employ an analytical approach based on the Hall method to estimate the impurity diffusion coefficients. Results of Al and Zn impurity diffusion in Mg are reported and compared to published impurity diffusion coefficients typically determined by thin film techniques.

  4. Development of ODS FeCrAl alloys for accident-tolerant fuel cladding

    SciTech Connect

    Dryepondt, Sebastien N.; Hoelzer, David T.; Pint, Bruce A.; Unocic, Kinga A.

    2015-09-18

    FeCrAl alloys are prime candidates for accident-tolerant fuel cladding due to their excellent oxidation resistance up to 1400 C and good mechanical properties at intermediate temperature. Former commercial oxide dispersion strengthened (ODS) FeCrAl alloys such as PM2000 exhibit significantly better tensile strength than wrought FeCrAl alloys, which would alloy for the fabrication of a very thin (~250 m) ODS FeCrAl cladding and limit the neutronic penalty from the replacement of Zr-based alloys by Fe-based alloys. Several Fe-12-Cr-5Al ODS alloys where therefore fabricated by ball milling FeCrAl powders with Y2O3 and additional oxides such as TiO2 or ZrO2. The new Fe-12Cr-5Al ODS alloys showed excellent tensile strength up to 800 C but limited ductility. Good oxidation resistance in steam at 1200 and 1400 C was observed except for one ODS FeCrAl alloy containing Ti. Rolling trials were conducted at 300, 600 C and 800 C to simulate the fabrication of thin tube cladding and a plate thickness of ~0.6mm was reached before the formation of multiple edge cracks. Hardness measurements at different stages of the rolling process, before and after annealing for 1h at 1000 C, showed that a thinner plate thickness could likely be achieved by using a multi-step approach combining warm rolling and high temperature annealing. Finally, new Fe-10-12Cr-5.5-6Al-Z gas atomized powders have been purchased to fabricate the second generation of low-Cr ODS FeCrAl alloys. The main goals are to assess the effect of O, C, N and Zr contents on the ODS FeCrAl microstructure and mechanical properties, and to optimize the fabrication process to improve the ductility of the 2nd gen ODS FeCrAl while maintaining good mechanical strength and oxidation resistance.

  5. Defective ZnFe2O4 nanorods with oxygen vacancy for photoelectrochemical water splitting

    NASA Astrophysics Data System (ADS)

    Kim, Ju Hun; Jang, Youn Jeong; Kim, Jin Hyun; Jang, Ji-Wook; Choi, Sun Hee; Lee, Jae Sung

    2015-11-01

    A one-dimensional zinc ferrite (ZnFe2O4) nanorod photoanode was prepared by a simple solution method on the F-doped tin oxide glass substrate. Thermal treatment under a hydrogen or vacuum atmosphere improved the photoelectrochemical water oxidation activity up to 20 times. The various physical characterization techniques used revealed that oxygen vacancies were created by the treatments in the near surface region, which increased the donor density and passivated the surface states. Hydrogen treatment was more effective and it was important to find optimum treatment conditions to take advantage of the positive role of oxygen vacancy as a source of electron donors and avoid its negative effect as electron trap sites.A one-dimensional zinc ferrite (ZnFe2O4) nanorod photoanode was prepared by a simple solution method on the F-doped tin oxide glass substrate. Thermal treatment under a hydrogen or vacuum atmosphere improved the photoelectrochemical water oxidation activity up to 20 times. The various physical characterization techniques used revealed that oxygen vacancies were created by the treatments in the near surface region, which increased the donor density and passivated the surface states. Hydrogen treatment was more effective and it was important to find optimum treatment conditions to take advantage of the positive role of oxygen vacancy as a source of electron donors and avoid its negative effect as electron trap sites. Electronic supplementary information (ESI) available: XANES and EXAFS spectra, light harvesting efficiency, HR-SEM images, vacuum-treated ZnFe2O4, equivalent circuit model, Nyquist plots, and charge separation efficiencies. See DOI: 10.1039/c5nr05812k

  6. Fe-tannic acid complex dye as photo sensitizer for different morphological ZnO based DSSCs.

    PubMed

    Çakar, Soner; Özacar, Mahmut

    2016-06-15

    In this paper we have synthesized different morphological ZnO nanostructures via microwave hydrothermal methods at low temperature within a short time. We described different morphologies of ZnO at different Zn(NO3)2/KOH mole ratio. The ZnO nanostructures were characterized via X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and UV-vis spectrophotometry. All ZnO structures have hexagonal wurtzite type structures. The FESEM images showed various morphologies of ZnO such as plate, rod and nanoparticles. Dye sensitized solar cells have been assembled by these different morphological structures photo electrode and tannic acid or Fe-tannic acid complex dye as sensitizer. We have achieved at maximum efficiencies of photovoltaic cells prepared with ZnO plate in all dye systems. The conversion efficiencies of dye sensitized solar cells are 0.37% and 1.00% with tannic acid and Fe-tannic acid complex dye, respectively. PMID:27043871

  7. Fe-tannic acid complex dye as photo sensitizer for different morphological ZnO based DSSCs

    NASA Astrophysics Data System (ADS)

    Çakar, Soner; Özacar, Mahmut

    2016-06-01

    In this paper we have synthesized different morphological ZnO nanostructures via microwave hydrothermal methods at low temperature within a short time. We described different morphologies of ZnO at different Zn(NO3)2/KOH mole ratio. The ZnO nanostructures were characterized via X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and UV-vis spectrophotometry. All ZnO structures have hexagonal wurtzite type structures. The FESEM images showed various morphologies of ZnO such as plate, rod and nanoparticles. Dye sensitized solar cells have been assembled by these different morphological structures photo electrode and tannic acid or Fe-tannic acid complex dye as sensitizer. We have achieved at maximum efficiencies of photovoltaic cells prepared with ZnO plate in all dye systems. The conversion efficiencies of dye sensitized solar cells are 0.37% and 1.00% with tannic acid and Fe-tannic acid complex dye, respectively.

  8. ZnFe2 O4 Leaves Grown on TiO2 Trees Enhance Photoelectrochemical Water Splitting.

    PubMed

    Zheng, Xue-Li; Dinh, Cao-Thang; de Arquer, F Pelayo García; Zhang, Bo; Liu, Min; Voznyy, Oleksandr; Li, Yi-Ying; Knight, Gordon; Hoogland, Sjoerd; Lu, Zheng-Hong; Du, Xi-Wen; Sargent, Edward H

    2016-06-01

    TiO2 has excellent electrochemical properties but limited solar photocatalytic performance in light of its large bandgap. One important class of visible-wavelength sensitizers of TiO2 is based on ZnFe2 O4 , which has shown fully a doubling in performance relative to pure TiO2 . Prior efforts on this important front have relied on presynthesized nanoparticles of ZnFe2 O4 adsorbed on a TiO2 support; however, these have not yet achieved the full potential of this system since they do not provide a consistently maximized area of the charge-separating heterointerface per volume of sensitizing absorber. A novel atomic layer deposition (ALD)-enhanced synthesis of sensitizing ZnFe2 O4 leaves grown on the trunks of TiO2 trees is reported. These new materials exhibit fully a threefold enhancement in photoelectrochemical performance in water splitting compared to pristine TiO2 under visible illumination. The new materials synthesis strategy relies first on the selective growth of FeOOH nanosheets, 2D structures that shoot off from the sides of the TiO2 trees; these templates are then converted to ZnFe2 O4 with the aid of a novel ALD step, a strategy that preserves morphology while adding the Zn cation to achieve enhanced optical absorption and optimize the heterointerface band alignment. PMID:27145726

  9. Surface modified multifunctional ZnFe2O4 nanoparticles for hydrophobic and hydrophilic anti-cancer drug molecule loading.

    PubMed

    Maiti, Debabrata; Saha, Arindam; Devi, Parukuttyamma Sujatha

    2016-01-21

    Multifunctional ZnFe2O4 nanoparticles were successfully synthesized via thermolysis of Fe-oleate and Zn-oleate precursors. Monodisperse, single phase ZnFe2O4 nanoparticles with an average particle size of ∼22 nm, exhibiting green emission (λmax∼ 480 nm) and ferromagnetism at room temperature (saturation magnetization of 48.46 emu gm(-1)) have been formed by this novel approach. By appropriate surface functionalization, these materials have been converted into smart carriers of hydrophobic (water insoluble) drug molecule-curcumin and hydrophilic (water soluble) drug molecule-daunorubicin. The in vitro cytotoxicity of both the hydrophobic and hydrophilic drug loaded ZnFe2O4 nanoparticles was studied using the conventional MTT assay which revealed that the drug loaded nanoparticles induce significant death of the carcinoma cells (HeLa). Interestingly, this appears to be a significant development towards the capability of surface functionalized multifunctional ZnFe2O4 nanoparticles as carriers for both water soluble and insoluble drugs for anti-cancer therapy. PMID:26524183

  10. Preparation of Modified Semi-Coke–Supported ZnFe2O4 Sorbent with the Assistance of Ultrasonic Irradiation

    PubMed Central

    Mi, Jie; Ren, Jun; Zhang, Yongyan

    2012-01-01

    Abstract Modified semi-coke (MSC) supported ZnFe2O4 was prepared under the condition of ultrasonic irradiation. Performance of the sorbents was tested using a fixed-bed reactor as a hot gas desulfurizer. The MSC support, the mass ratio of zinc ferrites to the support, calcination temperature, and the ultrasonic conditions of power and time all had influences on the structure and the breakthrough behavior of the sorbent. Ultrasonic irradiation can help to make ZnFe2O4 highly dispersed on MSC. ZnFe2O4/MSC had increased porosity and a larger specific surface area compared to unsupported ZnFe2O4. The sorbent exhibited a higher sulfur capacity at the optimum preparing conditions, where the mass ratio of ZnFe2O4 to MSC was 8:10, calcinated at 500°C, and the ultrasonic power and time was 900 W and 1.5 h, respectively. PMID:23133310

  11. Microstructural stability of Fe-Cr-Al alloys at 450-550 °C

    NASA Astrophysics Data System (ADS)

    Ejenstam, Jesper; Thuvander, Mattias; Olsson, Pär; Rave, Fernando; Szakalos, Peter

    2015-02-01

    Iron-Chromium-Aluminium (Fe-Cr-Al) alloys have been widely investigated as candidate materials for various nuclear applications. Albeit the excellent corrosion resistance, conventional Fe-Cr-Al alloys suffer from α-α‧ phase separation and embrittlement when subjected to temperatures up to 500 °C, due to their high Cr-content. Low-Cr Fe-Cr-Al alloys are anticipated to be embrittlement resistant and provide adequate oxidation properties, yet long-term aging experiments and simulations are lacking in literature. In this study, Fe-10Cr-(4-8)Al alloys and a Fe-21Cr-5Al were thermally aged in the temperature interval of 450-550 °C for times up to 10,000 h, and the microstructures were evaluated mainly using atom probe tomography. In addition, a Kinetic Monte Carlo (KMC) model of the Fe-Cr-Al system was developed. No phase separation was observed in the Fe-10Cr-(4-8)Al alloys, and the developed KMC model yielded results in good agreement with the experimental data.

  12. FeAl underlayers for CoCrPt thin film longitudinal media

    SciTech Connect

    Lee, L.; Laughlin, D.E.; Lambeth, D.N.

    1997-04-01

    B2 ordered FeAl films with a small, uniform grain size have been produced by rf diode sputter deposition on glass substrates. CoCrPt films grown on FeAl underlayers were found to have the (10{bar 1}0) lamellar texture. The in-plane coercivities (H{sub c}) of the CoCrPt/FeAl films are comparable to those of the CoCrPt/Cr films and they can be further improved by inserting a thin Cr intermediate layer between the CoCrPt and the FeAl layers. By employing a MgO seed layer or a (002) textured Cr seed layer, (001) textured FeAl can be obtained. However, the (001) FeAl underlayer only induces a weak (11{bar 2}0) textured CoCrPt. Thus no improvement in H{sub c} over those produced on unseeded FeAl underlayers was observed. {copyright} {ital 1997 American Institute of Physics.}

  13. Novel multifunctional NiFe2O4/ZnO hybrids for dye removal by adsorption, photocatalysis and magnetic separation

    NASA Astrophysics Data System (ADS)

    Zhu, Hua-Yue; Jiang, Ru; Fu, Yong-Qian; Li, Rong-Rong; Yao, Jun; Jiang, Sheng-Tao

    2016-04-01

    Novel multifunctional NiFe2O4/ZnO hybrids were prepared by a hydrothermal method and their physicochemical properties were characterized by XRD, SEM, TEM, TGA, VSM, BET and UV-vis DRS. The adsorption and photocatalytic performance of NiFe2O4/ZnO hybrids were systematically investigated using congo red as a model contaminant. With the introduction of NiFe2O4, NiFe2O4/ZnO hybrids can absorb the whole light from 300 nm to 700 nm. The adsorption capacity (221.73 mg g-1) of NiFe2O4/ZnO hybrids is higher than those of NiFe2O4, ZnO and mechanically mixed NiFe2O4/ZnO hybrids. The removal of congo red solution (20 mg L-1) by NiFe2O4/ZnO hybrids was about 94.55% under simulated solar light irradiation for 10 min. rad OH and h+ play important roles in the decolorization of congo red solution by NiFe2O4/ZnO hybrids under simulated solar light irradiation. The decolorization efficiency of congo red solution is 97.23% for the fifth time by NiFe2O4/ZnO hybrids under simulate solar light irradiation, indicating the high photostability and durability. NO3- and Cl- anions which are ubiquitous components in dye-containing wastewater have negligible influence on the effectiveness of NiFe2O4/ZnO hybrids. Moreover, the magnetic NiFe2O4/ZnO hybrids can be easily separated from the reacted solution by an external magnet.

  14. Al-doped MgZnO/p-AlGaN heterojunction and their application in ultraviolet photodetectors

    NASA Astrophysics Data System (ADS)

    Hsueh, Kuang-Po; Cheng, Po-Wei; Lin, Wen-Yen; Chiu, Hsien-Chin; Sheu, Jinn-Kong; Yeh, Yu-Hsiang

    2015-01-01

    In this study, n-type Al-doped MgxZn1-xO (AMZO) films were deposited onto p-Al0.08Ga0.92N by using radiofrequency magnetron sputtering followed by annealing at 800°C in nitrogen ambient for 60 s. The film was highly transparent and had transmittances exceeding 95% in the visible region and a sharp absorption edge visible in the ultraviolet region. A high leakage current was obtained in the current-voltage (I-V) characteristics of the GMZO/AlGaN n-p junction diode. The AMZO/AlGaN photodetector based on the AMZO film exhibited a dark current of 1.56 μA at Vbias = -3V. The peak responsivity of the photodetector was approximately 200 nm and a cutoff wavelength was observed at approximately 250 nm.

  15. Structural, Dielectric, Microstructural Properties of Ni0.7Zn0.3Fe2-xAlxO4 Ferrite Nanoparticles Through Citrate-Gel Method

    NASA Astrophysics Data System (ADS)

    Hashim, Mohd.; Alimuddin, Kumar, Shalendra; Ali, Sikander; Kumar, R.

    2011-07-01

    Study of structural and electrical properties of Al3+ doped Ni0.7Zn0.3Fe2-xAlxO4 (0.0≤x≤0.5) ferrite synthesized through citrate-gel method has been carried out. The samples were characterized by using XRD and dielectric technique in the frequency range 42 Hz-5 MHz at room temperature. X-ray diffraction studies confirmed that all the samples exhibit single phase cubic spinel structure. The variation in ɛ', and tanδ with frequency reveals that the dispersion is due to Maxwell-Wagner type of interfacial polarization in accordance with Koop's phenomenological theory.

  16. Magnetic properties of ultrasoft-nanocomposite FeAlSiBNbCu alloys

    NASA Astrophysics Data System (ADS)

    Todd, I.; Tate, B. J.; Davies, H. A.; Gibbs, M. R. J.; Kendall, D.; Major, R. V.

    2000-06-01

    The effects of up to 10 at% substitution of Fe by Al on the microstructure and DC and AC magnetic properties of nanocrystalline FeSiBCuNb alloy ribbon are summarised and analysed. The minimum DC H c developed during annealing decreases by 40% for 2 at% Al (to 0.3 A/m) and remains roughly constant for larger Al contents. The largest peak value of μ 0.4 at 50 Hz also corresponds to 2 at% Al. The best frequency response for μ 0.4 occurs for 6 at% Al while there was no improvement in AC power loss behaviour over the 0% Al alloy. The improvements in DC H c and AC μ 0.4 are ascribed to a reduction in K 1 of the Fe-Si-based nanocrystallites by the introduction of Al.

  17. Electronic structure and soft magnetic properties of Se/FeSiAl (110) films

    NASA Astrophysics Data System (ADS)

    Schwindt, V. Cardoso; Ardenghi, J. S.; Bechthold, P.; Juan, A.; Batic, B. Setina; Jenko, M.; González, E. A.; Jasen, P. V.

    2015-11-01

    The Se adsorption at different coverages on DO3 FeSiAl(110) surface is studied using density functional theory (DFT). Se adsorption is favorable in almost all surface high-symmetry sites, except for the bridge site formed by Fe-Si atoms. The most stable is a hollow site formed by four Fe atoms with adsorption energy of -5.30 eV. When the coverages increase, the energies decrease in the case of hollow sites. The surface present a reconstruction after Se adsorption, being the most important at 1/2 ML. The local magnetic moment for Fe atoms increase for the type A (all nearst neighbours (nn) are Fe atoms) and decrease for the type B (nn are Fe, Si and Al atoms). The most affected metal orbitals are Fe 4s and 4p. In the case of the hollow site the surface Fe-Fe bond is weakened after Se adsorption. A Fe-Se bond is developed at all coverages in both sites being the most important on top (dFe-Se = 2.23 Å, OP: 0.774 at 1/4 ML). The first and second layer Fe-Fe bond increase at 1/4 ML and decrease at 1/2 and 1 ML. Small Se-Se bonding interaction appear at 1/2 ML and increase noticeable for 1 ML. For the top site, the Se-Se bond appears at all coverage. The Fe-Fe surface bonds also decrease its strength with respect to the clean surface at all coverage. The first and second layer Fe-Fe bond increase at all coverage.

  18. L X-ray Production Cross Sections for Proton Impact on Fe, Cu, Zn, and Ge

    SciTech Connect

    Cipolla, Sam J.

    2009-03-10

    L x-rays excited by 50-minus;300 keV protons impacting thick targets of Fe, Cu, Zn, and Ge were measured with a high-resolution Si(Li) detector equipped with an ultra-thin window. L{sub l,{eta}}, L{sub {alpha}}{sub ,{beta}}{sub 1}, and L{sub {beta}}{sub 3,4} x-ray yields were derived from peak-fitting analysis of the measured x-ray spectra. The corresponding L{sub 1} and L{sub 2}+L{sub 3} sub-shell cross sections were compared with predictions of the ECPSSR theory.

  19. Microwave properties of RF- sputtered ZnFe{sub 2}O{sub 4} thin films

    SciTech Connect

    Garg, T. Kulkarni, A. R.; Venkataramani, N.; Sahu, B. N.; Prasad, Shiva

    2014-04-24

    In this work, RF- magnetron sputtering technique has been employed to deposit nanocrystalline ZnFe{sub 2}O{sub 4} thin films at room temperature. The as grown films were ex-situ annealed in air for 2 h at temperatures from 150°C to 650°C. X-ray diffraction, vibrating sample magnetometer and ferromagnetic resonance were used to analyze the phase formation, magnetic properties and microwave properties respectively. From the hysteresis loops and ferromagnetic resonance spectra taken at room temperature, a systematic study on the effect of O{sub 2} plasma on microwave properties with respect to processing temperature has been carried out.

  20. Assessing the elastic properties and ductility of Fe-Cr-Al alloys from ab initio calculations

    NASA Astrophysics Data System (ADS)

    Nurmi, E.; Wang, G.; Kokko, K.; Vitos, L.

    2016-01-01

    Fe-Al is one of the best corrosion resistant alloys at high temperatures. The flip side of Al addition to Fe is the deterioration of the mechanical properties. This problem can be solved by adding a suitable amount of third alloying component. In the present work, we use ab initio calculations based on density functional theory to study the elastic properties of Fe?Cr?Al? alloys for Al and Cr contents up to 20 at.%. We assess the ductility as a function of chemistry by making use of the semi-empirical correlations between the elastic parameters and mechanical properties. In particular, we derive the bulk modulus to shear modulus ratio and the Cauchy pressure and monitor their trends in terms of chemical composition. The present findings are contrasted with the previously established oxidation resistance of Fe-Cr-Al alloys.

  1. Synthesis and characterization of quasicrystals in an Al-Fe-W alloy

    SciTech Connect

    Mukhopadhyay, N.K.; Weatherly, G.C.; Embury, J.D. ); Lloyd, D.J. )

    1992-07-01

    After the discovery of quasicrystals (QC) in an al-14% Mn alloy, many attempts have been made to find alloy systems which form quasicrystals. Much effort has been devoted to the study of the Al-Fe system and its modification by Cu and other elements such as Mn, Cr, Mo and Ta to improve the ease of forming icosahedral quasicrystals (IQC). Although the Al-Fe system does not form IQC, the formation of a decagonal quasicrystal (DQC) being favored, these elements promote the IQC phase. This paper considers the Al-Fe system and its modification by W and demonstrates the existence of IQC in an Al-Fe-W ternary alloy.

  2. Point defect behavior in B2-type intermetallic compound FeAl

    SciTech Connect

    Haraguchi, T.; Kogachi, M.

    1999-07-01

    Point defect behavior in B2-type FeAl alloys is investigated from a thermodynamic point of view, based on the Bragg-Williams method. The model is developed by taking new defect formation mechanisms, random vacancy distribution (RVD), and antisite atom recovering (ASAR), into consideration, which were proposed based on the current findings in in situ neutron and X-ray diffraction studies for the B2 FeAl. The condition for appearance of the RVD and ASAR states is given. Application of this model to B2 FeAl alloys shows that the RVD-like behavior is reproduced in the Fe-rich composition region and also a rapid increase in vacancy concentration observed in the Al-rich region can be interpreted by the ASAR process by antisite Al atoms.

  3. Microstructure and cathodoluminescence study of sprayed Al and Sn doped ZnS thin films

    NASA Astrophysics Data System (ADS)

    El Hichou, A.; Addou, M.; Bubendorff, J. L.; Ebothé, J.; El Idrissi, B.; Troyon, M.

    2004-02-01

    Here we report on the study of ZnS and X-doped ZnS (with 4 at% of X = Al, Sn) thin films, prepared by spray pyrolysis technique using chloride precursors. Cathodoluminescence imaging and spectroscopy, x-ray diffraction, x-ray energy dispersive spectrometry and spectrophotometry have been used for their characterization. Deposited at their optimal substrate temperature (Ts = 773 K), these films are polycrystalline and consist of mixed hexagonal (agr) and cubic (bgr) phases with a predominance of the cubic phase. Their growth is preferentially oriented along the (111)bgr direction and their optical bandgap always remains close to 3.56 eV regardless of the sample considered. The cathodoluminescence spectra of ZnS and Al-ZnS films are similar and are characterized by a blue emission peak at 407 nm (3.05 eV) and a broad blue-green one located at 524 nm (2.36 eV) due to the presence of chlorine. The insertion of Sn2+ ions in the ZnS material leads to the formation of the SnCl2 compound and to the disappearance of the blue-green emission associated with Cl ionized donors.

  4. Multistage hydrothermal silicification and Fe-Tl-As-Sb-Ge-REE enrichment in the Red Dog Zn-Pb-Ag district, northern Alaska: Geochemistry, origin, and exploration applications

    USGS Publications Warehouse

    Slack, J.F.; Kelley, K.D.; Anderson, V.M.; Clark, J.L.; Ayuso, R.A.

    2004-01-01

    Geochemical analyses of major, trace, and rare earth elements (REE) in more than 200 samples of variably silicified and altered wall rocks, massive and banded sulfide, silica rock, and sulfide-rich and unmineralized barite were obtained from the Main, Aqqaluk, and Anarraaq deposits in the Red Dog Zn-Pb-Ag district of northern Alaska. Detailed lithogeochemical profiles for two drill cores at Aqqaluk display an antithetic relationship between SiO2/Al2O3 and TiO2/Zr which, together with textural information, suggest preferential silicification of carbonate-bearing sediments. Data for both drill cores also show generally high Tl, Sb, As, and Ge and uniformly positive Eu anomalies (Eu/Eu* > 1.0). Similar high Tl, Sb, As, Ge, and Eu/Eu* values are present in the footwall and shallow hanging wall of Zn-Pb-Ag sulfide intervals at Anarraaq but are not as widely dispersed. Net chemical changes for altered wall rocks in the district, on the basis of average Al-normalized data relative to unaltered black shales of the host Kuna Formation, include large enrichments (>50%) of Fe, Ba, Eu, V, S, Co, Zn, Pb, Tl, As, Sb, and Ge at both Red Dog and Anarraaq, Si at Red Dog, and Sr, U, and Se at Anarraaq. Large depletions (>50%) are evident for Ca at both Red Dog and Anarraaq, for Mg, P, and Y at Red Dog, and for Na at Anarraaq. At both Red Dog and Anarraaq, wall-rock alteration removed calcite and minor dolomite during hydrothermal decarbonation reactions and introduced Si, Eu, and Ge during silicification. Sulfidation reactions deposited Fe, S, Co, Zn, Pb, Tl, As, and Sb; barite mineralization introduced Ba, S, and Sr. Light REE and U were mobilized locally. This alteration and mineralization occurred during Mississippi an hydrothermal events that predated the Middle Jurassic-Cretaceous Brookian orogeny. Early hydrothermal silicification at Red Dog took place prior to or during massive sulfide mineralization, on the basis of the dominantly planar nature of Zn-Pb veins, which suggests

  5. Magnetoresistance effect in Ag-Fe3O4 and Al-Fe3O4 composite films

    NASA Astrophysics Data System (ADS)

    Hsu, Jen-Hwa; Chen, Shang-Yi; Chang, Wen-Ming; Jian, T. S.; Chang, Ching-Ray; Lee, Shan-Fan

    2003-05-01

    The Agx-(Fe3O4)1-x and Agx-(Fe3O4)1-x composite films were prepared by dc sputtering on Si(100) substrates. The x-ray diffraction results show that the films contain essentially only the cubic inverse spinal phase from Fe3O4 and face-centered cubic phase from Ag or Al. The transmission electron microscopy images indicate that the metal granules are randomly distributed with Fe3O4 grains. The resistivity determined from the four-probe method decreases rapidly with increasing metal content. At x≒0.5, a percolation occurs. The conducting path is formed from metal granules in series with Fe3O4 grains. The magnetoresistance (MR) is defined to be {R(H=0.8 T)-R(H=0)}/R(H=0). It has been found that MR is isotropic and the appearance of Ag granules has significant impact on the MR effect. Furthermore, a positive MR region appears with 0.011Fe3O4)1-x. On the contrary, the incorporation of Al granules does not have the same effect on MR as in Agx-(Fe3O4)1-x. A slow increase of MR with Al content might be due to Coulomb blockade. The extra contribution to MR in Agx-(Fe3O4)1-x can be attributed to spin injection from Fe3O4 into Ag granules so that spin accumulation in Ag granules impedes the current causing a larger resistance under a field.

  6. Comparative Studies of Cation Doping of ZnO with Mn, Fe, and Co

    NASA Astrophysics Data System (ADS)

    Jug, Karl; Tikhomirov, Viatcheslav A.

    2009-08-01

    MSINDO calculations were performed to elucidate the effect of doping and defects on the electronic properties of zinc oxide. The cyclic cluster Zn48O48 served as a model for the bulk. Band gaps and stabilities of spin states were determined for doping with Mn, Fe, and Co. It was found that a substantial lowering of the band gap occurs for Mn and Co doping. In contrast, the Fe doping has a rather insignificant effect on the band gap. Additional defects such as oxygen vacancy, zinc interstitial, or zinc vacancy were also studied. In the case of substitution of zinc by two transition metal atoms, various spin states arise which can be classified as antiferromagnetic, ferrimagnetic, or ferromagnetic. We find that the spin state with the lowest multiplicity, antiferromagentic or ferrimagnetic, is more stable than the high-multiplicity ferromagnetic state in most considered cases, but additional zinc vacancies or mixed doping may reverse this trend.

  7. Ellipsometric investigation of ZnFe2O4 thin films in relation to magnetic properties

    NASA Astrophysics Data System (ADS)

    Zviagin, V.; Kumar, Y.; Lorite, I.; Esquinazi, P.; Grundmann, M.; Schmidt-Grund, R.

    2016-03-01

    We report an influence of disorder on structural and magnetic properties of ZnFe2O4 thin films grown at temperatures ranging from 400 °C to 600 °C by pulsed laser deposition in O2 atmosphere on SrTiO3 (100) substrates evidenced by properties of electronic transitions observed in the dielectric function. Inversion of the normal spinel structure was found to be one of the main mechanisms responsible for the increase in the magnetic response for the lowest growth temperature. The enhanced feature in the dielectric function located at ˜3.5 eV, related to the transition involving tetrahedrally coordinated Fe3+ cations, corresponds to the dominating magnetic coupling between the octahedral and tetrahedral lattice sites, responsible for the overall ferrimagnetic behaviour of the film grown at the lowest temperature.

  8. Room-temperature serrated-flow behavior in Fe-rich FeAl under vacancy supersaturation

    SciTech Connect

    Yoshimi, K.; Yoo, M.H.; Hanada, S.

    1998-11-01

    In Fe-rich FeAl, serrated plastic-flow behavior has been observed for the first time at room temperature. Serration on the tensile stress-strain curve occurs in single crystals that retained supersaturation of thermal vacancies after fast-cooling from the annealing temperature of 1173 K. In contrast to conventional serrated flow, the serrated flow in FeAl is associated with work hardening, and it becomes more pronounced with increasing Al content from 33 to 44 mol.%. The experimental results are interpreted in terms of the dynamic interaction of ({bar 1}01)[111] superdislocations with the excess thermal vacancies and their clusters, and the successive double cross-slip of screw superdislocations at the moving front of a slip band. The strong dependence on alloy composition and the lack of strain-rate sensitivity are discussed.

  9. NiZn ferrite/Fe hybrid epoxy-based composites: extending magnetic properties to high frequency

    NASA Astrophysics Data System (ADS)

    Wang, Yunqi; Grant, Patrick S.

    2014-08-01

    Hybrid ferromagnetic composites composed of Ni0.4Zn0.6Fe2O4 ferrite powder and Fe particles in an epoxy matrix with various composition ratios were prepared by a simple mould casting route. Planetary ball milling was then introduced to pre-grind Fe and NiZn ferrite filler mixtures before casting, which resulted in fragmentation of the NiZn ferrites and modification of the Fe morphology from spherical particles to sub-micron flakes. Composites containing the ball-milled fillers exhibited a remarkable improvement in electromagnetic properties over the as-supplied materials, especially in the suppression of dielectric and magnetic loss. By combining the characteristics of high resonant frequency of the Fe and low energy losses of the ferrite, an optimum mixture of ball-milled 15 vol% NiZn ferrite and 38 vol% Fe in a hybrid epoxy-based composite gave an approximately one order of magnitude higher extended operating bandwidth over a ferrite-only containing composite, suppressing dielectric and magnetic loss tangents to approximately 10-2 up to 150 MHz without significant deterioration of permeability. This approach of manipulating multi-phase ferromagnetic material fractions and their structure provide for flexibility in the development of bespoke electromagnetic materials for applications in electrically small antenna and metamaterials.

  10. Thermodynamic analysis of chemical compatibility of several compounds with Fe-Cr-Al alloys

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.

    1993-01-01

    Chemical compatibility between Fe-19.8Cr-4.8Al (weight percent), which is the base composition for the commercial superalloy MA956, and several carbides, borides, nitrides, oxides, and silicides was analyzed from thermodynamic considerations. The effect of addition of minor alloying elements, such as Ti, Y, and Y2O3, to the Fe-Cr-Al alloy on chemical compatibility between the alloy and various compounds was also analyzed. Several chemically compatible compounds that can be potential reinforcement materials and/or interface coating materials for Fe-Cr-Al based composites were identified.

  11. Effect of surface roughness on the development of protective Al 2O 3 on Fe-10Al (at.%) alloys containing 0-10 at.% Cr

    NASA Astrophysics Data System (ADS)

    Zhang, Z. G.; Hou, P. Y.; Gesmundo, F.; Niu, Y.

    2006-11-01

    The effect of alloy surface roughness, achieved by different degrees of surface polishing, on the development of protective alumina layer on Fe-10 at.% Al alloys containing 0, 5, and 10 at.% Cr was investigated during oxidation at 1000 °C in 0.1 MPa oxygen. For alloys that are not strong Al 2O 3 formers (Fe-10Al and Fe-5Cr-10Al), the rougher surfaces increased Fe incorporation into the overall surface layer. On the Fe-10Al, more iron oxides were formed in a uniform layer of mixed aluminum- and iron-oxides since the layer was thicker. On the Fe-5Cr-10Al, more iron-rich nodules developed on an otherwise thin Al 2O 3 surface layer. These nodules nucleated preferentially along surface scratch marks but not on alloy grain boundaries. For the strong Al 2O 3-forming Fe-10Cr-10Al alloy, protective alumina surface layers were observed regardless of the surface roughness. These results indicate that the formation of a protective Al 2O 3 layer on Fe-Cr-Al surfaces is not dictated by Al diffusion to the surface. More cold-worked surfaces caused an enhanced Fe diffusion, hence produced more Fe-rich oxides during the early stage of oxidation.

  12. Investigation on Spin Dependent Transport Properties of Core-Shell Structural Fe3O4/ZnS Nanocomposites for Spintronic Application

    PubMed Central

    Liu, Er; Yuan, Honglei; Kou, Zhaoxia; Wu, Xiumei; Xu, Qingyu; Zhai, Ya; Sui, Yunxia; You, Biao; Du, Jun; Zhai, Hongru

    2015-01-01

    The core-shell structural Fe3O4/ZnS nanocomposites with controllable shell thickness were well-fabricated via seed-mediate growth method. Structural and morphological characterizations reveal the direct deposition of crystalline II-VI compound semiconductor ZnS shell layer on Fe3O4 particles. Spin dependent electrical transport is studied on Fe3O4/ZnS nanocomposites with different shell thickness, and a large magnetoresistance (MR) ratio is observed under the magnetic field of 1.0 T at room temperature and 100 K for the compacted sample by Fe3O4/ZnS nanocomposites, which is 50% larger than that of sample with pure Fe3O4 particles, indicating that the enhanced MR is contributed from the spin injection between Fe3O4 and ZnS layer. PMID:26053888

  13. Fe, Zn, and Cd stable isotopes from the eastern tropical South Pacific from GEOTRACES cruise GP16 - Methods and data

    NASA Astrophysics Data System (ADS)

    Helgoe, J. M.; Townsend, E.; John, S.

    2014-12-01

    A new method has been developed for the rapid analysis of metal concentrations and stable isotope ratios using a prepFAST automated sample processing robot. Although concentrations and isotopes are processed separately, similar methods are used for both. Initially all seawater is acidified to pH 2. Then Nobias resin with EDTA/IDA functional groups is added to either 10mL of sample for concentrations or ~1L samples for isotopes. Fe binds to the resin at low pH, and the pH is subsequently raised to allow Zn and Cd to bind. For concentration analyses, all subsequent chemistry is automated on the prepFAST including removal of seawater, rinsing of resin, and elution of resin into acid. For isotope samples these extraction techniques are performed manually, but the subsequent purification of Fe, Zn, and Cd by anion exchange chromatography is automated using the prepFAST. With these new methods, samples from the US GEOTRACES cruise GP16, in the eastern tropical South Pacific, are being analyzed. High concentrations of dissolved Fe are observed near the continental shelf and near submarine hydrothermal vents. Interestingly, isotope data show that dissolved Fe near the continental shelf generally has a δ56Fe close to 0 ‰. This δ56 Fe signature is suggestive of a non-reductive dissolution source for Fe, as Fe(II) released by reductive dissolution is typically closer to -2 ‰. Preliminary data show nutrient-type profiles for Zn and Cd, with Zn matching Si and Cd having a similar distribution to P. An increase in dissolved Zn near hydrothermal vents suggests a possible hydrothermal zinc source to the deep ocean. Continuing analysis of isotope data will reveal more about the source and biogeochemical cycling of these three chemically and biologically important trace metals throughout the eastern tropical Pacific Ocean.

  14. Constitutive expression of the ZmZIP7 in Arabidopsis alters metal homeostasis and increases Fe and Zn content.

    PubMed

    Li, Suzhen; Zhou, Xiaojin; Zhao, Yongfeng; Li, Hongbo; Liu, Yuanfeng; Zhu, Liying; Guo, Jinjie; Huang, Yaqun; Yang, Wenzhu; Fan, Yunliu; Chen, Jingtang; Chen, Rumei

    2016-09-01

    Iron (Fe) and zinc (Zn) are important micronutrients for plant growth and development. Zinc-regulated transporters and the iron-regulated transporter-like protein (ZIP) are necessary for the homeostatic regulation of these metal micronutrients. In this study, the physiological function of ZmZIP7 which encodes a ZIP family transporter was characterized. We detected the expression profiles of ZmZIP7 in maize, and found that the accumulation of ZmZIP7 in root, stem, leaf, and seed was relatively higher than tassel and young ear. ZmZIP7 overexpression transgenic Arabidopsis lines were generated and the metal contents in transgenic and wild-type (WT) plants were examined using inductively coupled plasma atomic emission spectroscopy (ICP-OES) and Zinpyr-1 staining. Fe and Zn concentrations were elevated in the roots and shoots of ZmZIP7-overexpressing plants, while only Fe content was elevated in the seeds. We also analyzed the expression profiles of endogenous genes associated with metal homeostasis. Both endogenic Fe-deficiency inducible genes and the genes responsible for Zn and Fe transport and storage were stimulated in ZmZIP7 transgenic plants. In conclusion, ZmZIP7 encodes a functional Zn and Fe transporter, and ectopic overexpression of ZmZIP7 in Arabidopsis stimulate endogenous Fe and Zn uptake mechanisms, thereby facilitating both metal uptake and homeostasis. Our results contribute to improved understanding of ZIP family transporter functions and suggest that ZmZIP7 could be used to enhance Fe levels in grains. PMID:27135812

  15. Structural, electrical, and optical properties of atomic layer deposition Al-doped ZnO films

    SciTech Connect

    Banerjee, P; Lee, W. J.; Bae, K. R.; Lee, Sang Bok; Rubloff, Gary W

    2010-01-01

    Al-doped ZnO (AZO) films of ∼100 nm thickness with various Aldoping were prepared at 150 °C by atomic layer deposition on quartz substrates. At low Aldoping, the films were strongly textured along the [100] direction, while at higher Aldoping the films remained amorphous. Atomic force microscopy results showed that Al–O cycles when inserted in a ZnOfilm, corresponding to a few atomic percent Al, could remarkably reduce the surface roughness of the films. Hall measurements revealed a maximum mobility of 17.7 cm{sup 2} /V s . Film resistivity reached a minima of 4.4×10{sup −3}  Ω cm whereas the carrier concentration reached a maxima of 1.7×10{sup 20}  cm{sup −3} , at 3 at. % Al. The band gap of AZO films varied from 3.23 eV for undoped ZnOfilms to 3.73 eV for AZO films with 24.6 at. % Al. Optical transmittance over 80% was obtained in the visible region. The detrimental impact of increased Al resulting in decreased conductivity due to doping past 3.0 at. % is evident in the x-ray diffraction data, as an abrupt increase in the optical band gap and as a deviation from the Burstein–Moss effect.

  16. Electrical and optical properties of in and Al doped ZnO thin film

    NASA Astrophysics Data System (ADS)

    Park, Sang-Uk; Koh, Jung-Hyuk

    2013-07-01

    In this study, to improve the electrical and optical properties of aluminium (Al) doped zinc oxide thin films, we have added small amounts of indium (In) to Al doped ZnO thin films. We will present the results of In and Al doped ZnO thin film on glass substrates prepared by the sol-gel processing method. A rapid thermal annealing process was applied to cure the thin film properties. Different amounts of In were used to dope the AZO thin films to find the optimum process condition. The effects of crystallinity were analyzed by an x-ray diffraction method. In addition, the optical transmittance and electrical proprties of In doped AZO thin films were investigated.

  17. The feasibility of Sn, In, or Al doped ZnSb thin film as candidates for phase change material

    NASA Astrophysics Data System (ADS)

    Chen, Yimin; Shen, Xiang; Wang, Guoxiang; Xu, Tiefeng; Wang, Rongping; Dai, Shixun; Nie, Qiuhua

    2016-07-01

    The potentials of Sn, In, or Al doped ZnSb thin film as candidates for phase change materials have been studied in this paper. It was found that the Zn-Sb bonds were broken by the addition of the dopants and homopolar Zn-Zn bonds and other heteropolar bonds, such as Sn-Sb, In-Sb, and Al-Sb, were subsequently formed. The existence of homopolar Sn-Sn and In-In bonds in Zn50Sb36Sn14 and Zn41Sb36In23 films, but no any Al-Al bonds in Zn35Sb30Al35 film, was confirmed. All these three amorphous films crystallize with the appearance of crystalline rhombohedral Sb phase, and Zn35Sb30Al35 film even exhibits a second crystallization process where the crystalline AlSb phase is separated out. The Zn35Sb30Al35 film exhibits a reversible phase change behavior with a larger Ea (˜4.7 eV), higher Tc (˜245 °C), better 10-yr data retention (˜182 °C), less incubation time (20 ns at 70 mW), and faster complete crystallization speed (45 ns at 70 mW). Moreover, Zn35Sb30Al35 film shows the smaller root-mean-square (1.654 nm) and less change of the thickness between amorphous and crystalline state (7.5%), which are in favor of improving the reliability of phase change memory.

  18. Preparation and magnetic properties of BaFe12O19/Ni0.8Zn0.2Fe2O4 nanocomposite ferrite

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Huang, Ying; Wang, Qiufen

    2012-09-01

    Nanocomposite of hard (BaFe12O19)/soft ferrite (Ni0.8Zn0.2Fe2O4) have been prepared by the sol-gel process. The nanocomposite ferrite are formed when the calcining temperature is above 800 °C. It is found that the magnetic properties strongly depend on the presintering treatment and calcining temperature. The “bee waist” type hysteresis loops for samples disappear when the presintering temperature is 400 °C and the calcination temperature reaches 1100 °C owing to the exchange-coupling interaction. The remanence of BaFe12O19/Ni0.8Zn0.2Fe2O4 nanocomposite ferrite with the mass ratio of 5:1 is higher than a single phase ferrite. The specific saturation magnetization, remanence magnetization and coercivity are 63 emu/g, 36 emu/g and 2750 G, respectively. The exchange-coupling interaction in the BaFe12O19/Ni0.8Zn0.2Fe2O4 nanocomposite ferrite is discussed.

  19. Synthesis and magnetic properties of hard/soft SrFe12O19/Ni0.7Zn0.3Fe2O4 nanocomposite magnets

    NASA Astrophysics Data System (ADS)

    Radmanesh, M. A.; Seyyed Ebrahimi, S. A.

    2012-09-01

    Magnetic nanocomposite SrFe12O19/Ni0.7Zn0.3Fe2O4 powders with different weight fractions of the Ni0.7Zn0.3Fe2O4 soft ferrite were synthesized by a combination of the sol-gel self-propagation and glyoxilate precursor methods. The results of magnetic measurements revealed the higher Mr/Ms ratio for the nanocomposites than that for the single phase SrFe12O19 which proves the existence of the intergrain exchange coupling between hard and soft magnetic phases with the exchange spring behavior. The highest Mr/Ms ratio of 0.63 was obtained in the composite consisting of 80 wt% of SrFe12O19 and 20 wt% Ni0.7Zn0.3Fe2O4. The microstructural studies of this sample exhibited the average dimensions of hard and soft phases about 20 nm and 15 nm, respectively which are small enough for strong exchange coupling according to the theoretical studies. The variations of the reduced remanence (Mr/Ms) with increasing the weight fraction of the soft phase could be also explained by the role of the exchange and dipolar interactions in tuning the magnetic properties of the nanocomposites.

  20. Tribological Properties of the Fe-Al-Cr Alloyed Layer by Double Glow Plasma Surface Metallurgy

    NASA Astrophysics Data System (ADS)

    Luo, Xixi; Yao, Zhengjun; Zhang, Pingze; Zhou, Keyin; Wang, Zhangzhong

    2016-07-01

    A Fe-Al-Cr alloyed layer was deposited onto the surface of Q235 low-carbon steel via double glow plasma surface metallurgy (DGPSM) to improve the steel's wear resistance. After the DGPSM treatment, the Fe-Al-Cr alloyed layer grown on the Q235 low-carbon steel was homogeneous and compact and had a thickness of 25 µm. The layer was found to be metallurgically adhered to the substrate. The frictional coefficient and specific wear rate of the sample with a Fe-Al-Cr alloyed layer (treated sample) were both lower than those of the bare substrate (untreated sample) at the measured temperatures (25, 250 and 450 °C). The results indicated that the substrate and the alloyed layer suffered oxidative wear and abrasive wear, respectively, and that the treated samples exhibited much better tribological properties than did the substrate. The formation of Fe2AlCr, Fe3Al(Cr), FeAl(Cr), Fe(Cr) sosoloid and Cr23C6 phases in the alloyed layer dramatically enhanced the wear resistance of the treated sample. In addition, the alloyed layer's oxidation film exhibited a self-healing capacity with lubrication action that also contributed to the improvement of the wear resistance at high temperature. In particular, at 450 °C, the specific wear rate of treated sample was 2.524 × 10-4 mm3/N m, which was only 45.2% of the untreated sample.

  1. Development of weldable, corrosion-resistant iron-aluminide (FeAl) alloys

    SciTech Connect

    Maziasz, P.J.; Goodwin, G.M.; Wang, X.L.; Alexander, D.J.

    1997-04-01

    A boron-microalloyed FeAl alloy (Fe-36Al-0.2Mo-0.05Zr-0.13C, at.%, with 100-400 appm B) with improved weldability and mechanical properties was developed in FY 1994. A new scale-up and industry technology development phase for this work began in FY 1995, pursuing two parallel paths. One path was developing monolithic FeAl component and application technology, and the other was developing coating/cladding technology for alloy steels, stainless steels and other Fe-Cr-Ni alloys. In FY 1995, it was found that cast FeAl alloys had good strength at 700-750{degrees}C, and some (2.5%) ductility in air at room-temperature. Hot-extruded FeAl with refined grain size was found to have ductility and to also have good impact-toughness at room-temperature. Further, it was discovered that powder-metallurgy (P/M) FeAl, consolidated by direct hot-extrusion at 950-1000{degrees}C to have an ultra fine-grained microstructure, had the highest ductility, strength and impact-toughness ever seen in such intermetallic alloys.

  2. Structural, electrical, and optomagnetic tweaking of Zn doped CoFe2-xZnxO4-δ nanoparticles

    NASA Astrophysics Data System (ADS)

    Agrawal, Shraddha; Parveen, Azra; Azam, Ameer

    2016-09-01

    Nanoparticles of pure and Zn doped CoFe2O4 of the composition CoFe2-xZnxO4-δ (x=0, 0.05, 0.10, 0.15) have been successfully synthesized by microwave gel combustion. The microstructural and compositional analyses were carried out by X-ray diffraction, Scanning Electron Microscopy. The crystallite size was found to increase with the increase in the Zn content. The dielectric constant (ε) and A.C. conductivity were studied as a function of frequency and temperature and were explained on the basis of Maxwell-Wagner model and electron hopping respectively. The energy band gap was found to decrease gradually with Zn doping. The magnetic measurements, depicts an increase in magnetization with the increase in Zn concentration, which in turn shows a strong dependency on the particle size. The magnetic hysteresis loop confirms the ferromagnetic nature.

  3. Effect of ZnO channel thickness on the device behaviour of nonvolatile memory thin film transistors with double-layered gate insulators of Al2O3 and ferroelectric polymer

    NASA Astrophysics Data System (ADS)

    Yoon, Sung-Min; Yang, Shin-Hyuk; Park, Sang-Hee Ko; Jung, Soon-Won; Cho, Doo-Hee; Byun, Chun-Won; Kang, Seung-Youl; Hwang, Chi-Sun; Yu, Byoung-Gon

    2009-12-01

    Poly(vinylidene fluoride trifluoroethylene) and ZnO were employed for nonvolatile memory thin film transistors as ferroelectric gate insulator and oxide semiconducting channel layers, respectively. It was proposed that the thickness of the ZnO layer be carefully controlled for realizing the lower programming voltage, because the serially connected capacitor by the formation of a fully depleted ZnO channel had a critical effect on the off programming voltage. The fabricated memory transistor with Al/P(VDF-TrFE) (80 nm)/Al2O3 (4 nm)/ZnO (5 nm) exhibits encouraging behaviour such as a memory window of 3.8 V at the gate voltage of -10 to 12 V, and 107 on/off ratio, and a gate leakage current of 10-11 A.

  4. The electronic and optical properties of Al2O3, MO, and MAl2O4 (M = Zn, Mg).

    PubMed

    Zhang, Fang-Ying; Zeng, Z; You, J Q

    2010-08-01

    The electronic properties and the imaginary parts of the dielectric function for nanosized ZnAl2O4 and MgAl2O4 are studied compared with those of B4-ZnO, B1-MgO and alpha-Al2O3 using a first-principles pesudopotential plane-wave method. The results show that both the electronic structures and the optical spectra of ZnAl2O4 and MgAl2O4 are different from those of ZnO, MgO and Al2O3 due to the atomic rearrangement, which agrees with the experimental data. The insight mechanism is also discussed. PMID:21125922

  5. Magnetic and structural properties of NiFe 2O 4 ferrite nanopowder doped with Zn 2+

    NASA Astrophysics Data System (ADS)

    Costa, A. C. F. M.; Silva, V. J.; Cornejo, D. R.; Morelli, M. R.; Kiminami, R. H. G. A.; Gama, L.

    This work involved an investigation to ascertain how the substitution of nickel ions for zinc ions affects the structural, morphological and magnetic properties of NiFe 2O 4 ferrite samples. Ni 1-xZn xFe 2O 4 ( x=0.0, 0.3 0.5, 0.7) powders were prepared by combustion reaction and characterized structurally by X-ray diffraction. The specific surface area of the powders was determined by the nitrogen adsorption method (BET). Magnetization measurements were taken using an alternative gradient magnetometer (AGM), which revealed that the powders prepared by combustion reaction resulted in nanosized particles with a particle size of 18-27 nm. The crystallite size and lattice parameter increased as the concentration of Zn increased. Moreover, augmenting the Zn content in the NiFe 2O 4 ferrite increased the saturation magnetization and coercive field.

  6. High-frequency permeability and permittivity of Ni xZn (1-x)Fe 2O 4 thick film

    NASA Astrophysics Data System (ADS)

    Kulkarni, D. C.; Lonkar, U. B.; Puri, Vijaya

    Magnetic materials such as Ni xZn (1-x)Fe 2O 4 have resonant frequency in high frequency; therefore, they are more useful especially in microwaves. The Ni xZn (1-x)Fe 2O 4 was prepared by the chemical coprecipitation method using citrate precursors, and the fritless thick film was screen printed on alumina substrates. The composition-dependent permeability and permittivity in the high frequency 8-12 GHz are investigated. Using the overlay technique on Ag-thick-film patch antenna, the change in reflectance and transmittance has been measured. The Ni xZn (1-x)Fe 2O 4 thick film, when used as overlay on Ag-thick-film patch antenna, changes the resonance characteristics. The changes in resonance frequency, reflectance and transmittance have been used to calculate the permeability and permittivity of the thick film. Zinc-concentration-dependent changes are obtained.

  7. Corrosion Resistance of Fe-Al/Al2O3 Duplex Coating on Pipeline Steel X80 in Simulated Oil and Gas Well Environment

    NASA Astrophysics Data System (ADS)

    Huang, Min; Wang, Yu; Wang, Ping-Gu; Shi, Qin-Yi; Zhang, Meng-Xian

    2015-04-01

    Corrosion resistant Fe-Al/Al2O3 duplex coating for pipeline steel X80 was prepared by a combined treatment of low-temperature aluminizing and micro-arc oxidation (MAO). Phase composition and microstructure of mono-layer Fe-Al coating and Fe-Al/Al2O3 duplex coating were studied by X-ray diffraction (XRD), scanning electron microscope (SEM) with energy dispersive spectrometer (EDS). Corrosion resistance of the coated pipeline steel X80 in a simulated oil and gas well condition was also investigated. Mono-layer Fe-Al coating consists of Fe2Al5 and FeAl, which is a suitable transitional layer for the preparation of ceramic coating by MAO on the surface of pipeline steel X80. Under the same corrosion condition at 373 K for 168 h with 1 MPa CO2 and 0.1 MPa H2S, corrosion weight loss rate of pipeline steel X80 with Fe-Al/Al2O3 duplex coating decreased to 23% of original pipeline steel X80, which improved by 10% than that of pipeline steel X80 with mono-layer Fe-Al coating. It cannot find obvious cracks and pits on the corrosion surface of pipeline steel X80 with Fe-Al/Al2O3 duplex coating.

  8. Ferromagnetism studies of Cu-doped and (Cu, Al) co-doped ZnO thin films

    NASA Astrophysics Data System (ADS)

    Wu, S. Z.; Yang, H. L.; Xu, X. G.; Miao, J.; Jiang, Y.

    2011-01-01

    We have studied the room temperature ferromagnetism (FM) in Cu-doped and (Cu, Al) co-doped ZnO thin films which were grown on quartz substrates by chemical method based on a sol-gel process combining with spin-coating technology. X-ray diffraction (XRD) patterns demonstrate that both the Cu-doped and (Cu, Al) co-doped ZnO films have the hexagonal wurtzite structure with c-axis orientation. Alternating Gradient Magnetometer (AGM) measurements confirm that all the doped ZnO samples are ferromagnetic at room temperature. When the doped Cu content is 1 %, the Cu-doped ZnO film has the strongest FM. The FM significantly decreases in the (Cu, Al) co-doped ZnO films. The doping of Al ions suppresses the FM induced by the doped Cu ions.

  9. Formation of Al-doped ZnO thin films on glass by sol-gel process and characterization

    NASA Astrophysics Data System (ADS)

    Shahid, M. U.; Deen, K. M.; Ahmad, A.; Akram, M. A.; Aslam, M.; Akhtar, W.

    2016-02-01

    In this study, pure ZnO and Al-doped ZnO thin films were developed on glass by sol-gel process followed by drying and annealing in air at 170 and 400 °C, respectively. The surface morphology and structural characteristics were determined through scanning electron microscopy, atomic force microscopy and X-ray diffraction. The Fourier transform infrared spectroscopy validated the formation of Al-doped ZnO film on glass substrate. It was evaluated that 1 at% aluminum (Al) doping in ZnO film showed low electrical resistivity and higher charge carrier concentration due to uniformly dispersed regular shape crystallites as compared to pure ZnO and 2 at% `Al'-doped thin films.

  10. Theoretical analysis of compatibility of several reinforcement materials with NiAl and FeAl matrices

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.

    1989-01-01

    Several potential reinforcement materials were assessed for their chemical, coefficient of thermal expansion (CTE), and mechanical compatibility with the intermetallic matrices based on NiAl and FeAl. Among the ceramic reinforcement materials, Al2O3, TiC, and TiB2, appear to be the optimum choices for NiAl and FeAl matrices. However, the problem of CTE mismatch with the matrix needs to be solved for these three reinforcement materials. Beryllium-rich intermetallic compounds can be considered as potential reinforcement materials provided suitable reaction barrier coatings can be developed for these. Based on preliminary thermodynamic calculations, Sc2O3 and TiC appear to be suitable as reaction barrier coatings for the beryllides. Several reaction barrier coatings are also suggested for the currently available SiC fibers.

  11. Alloy development of FeAl aluminide alloys for structural use in corrosive environments

    SciTech Connect

    Liu, C.T.; Sikka, V.K.; McKamey, C.G.

    1993-02-01

    Objectives include adequate ductilities ([ge]10%) at ambient temperature, high-temperature strength better than stainless steels (types 304 and 316), and fabricability and weldability by conventional techniques (gas tungsten arc). The alloys should be capable of being corrosion resistant in molten nitrate salts with rates lower than other iron-base structural alloys and coating materials (such as Fe-Cr-Al alloys). Such corrosion rates should be less than 0.3 mm per year. The FeAl aluminide containing 35.8 at. % Al was selected as base composition. Preliminary studies indicate that additions of B and Zr, increase the room-temperature ductility of FeAl. Further alloying with 0.2% Mo, and/or 5% Cr, improves the creep. Our preliminary alloying effort has led to identification of the following aluminide composition with promising properties: Fe - (35 [plus minus] 2)Al - (0.3 [plus minus] 0.2)Mo - (0.2 [plus minus] 0.15)Zr - (0.3 [plus minus] 0.2)B- up to 5Cr, at. %. However, this composition is likely to be modified in future work to improve the weldability of the alloy. The FeAl alloy FA-362 (Fe-35.8% Al-0.2% Mo-0.05% Zr-0.24% B) produced by hot extrusion at 900C showed a tensile ductility of more than 10% at room temperature and a creep rupture life longer than unalloyed FeAl by more than an order of magnitude at 593C at 138 MPa. Melting and processing of scaled-up heats of selected FeAl alloys are described. Forging, extruding, and hot-rolling processes for the scale-up heats are also described.

  12. Alloy development of FeAl aluminide alloys for structural use in corrosive environments

    SciTech Connect

    Liu, C.T.; Sikka, V.K.; McKamey, C.G.

    1993-02-01

    Objectives include adequate ductilities ({ge}10%) at ambient temperature, high-temperature strength better than stainless steels (types 304 and 316), and fabricability and weldability by conventional techniques (gas tungsten arc). The alloys should be capable of being corrosion resistant in molten nitrate salts with rates lower than other iron-base structural alloys and coating materials (such as Fe-Cr-Al alloys). Such corrosion rates should be less than 0.3 mm per year. The FeAl aluminide containing 35.8 at. % Al was selected as base composition. Preliminary studies indicate that additions of B and Zr, increase the room-temperature ductility of FeAl. Further alloying with 0.2% Mo, and/or 5% Cr, improves the creep. Our preliminary alloying effort has led to identification of the following aluminide composition with promising properties: Fe - (35 {plus_minus} 2)Al - (0.3 {plus_minus} 0.2)Mo - (0.2 {plus_minus} 0.15)Zr - (0.3 {plus_minus} 0.2)B- up to 5Cr, at. %. However, this composition is likely to be modified in future work to improve the weldability of the alloy. The FeAl alloy FA-362 (Fe-35.8% Al-0.2% Mo-0.05% Zr-0.24% B) produced by hot extrusion at 900C showed a tensile ductility of more than 10% at room temperature and a creep rupture life longer than unalloyed FeAl by more than an order of magnitude at 593C at 138 MPa. Melting and processing of scaled-up heats of selected FeAl alloys are described. Forging, extruding, and hot-rolling processes for the scale-up heats are also described.

  13. Microstructure and mechanical behavior of Fe30Ni 20Mn35Al15 and modified Fe30Ni 20Mn35Al15 alloys

    NASA Astrophysics Data System (ADS)

    Meng, Fanling

    A novel alloy with nominal composition Fe30Ni 20Mn35Al15 has been found to show good room-temperature strength and significant ductility. The current project is to study the wear properties of as-cast Fe30Ni20Mn35Al 15 and discuss the possibility of further improving the mechanical properties of this alloy. The dry sliding wear of as-cast Fe30Ni20Mn 35Al15 was studied in in four different environments, i.e. air, dry oxygen, dry argon and a 4% hydrogen/nitrogen mixture. Two-body and three-body abrasive wear mechanism was found for tests in oxygen-containing environments, while plastic flow mechanisms dominated the wear behavior for tests in argon. Hydrogen embrittlement led to 1000% increase of wear loss by causing more rapid crack nucleation of the asperities. The effects of different additions of chromium (≤ 8 at. %) on both microstructure and fracture behavior of Fe30Ni20Mn 35Al15 were investigated. All alloys consisted of (Ni, Al)-rich B2 and (Fe, Mn)-rich f.c.c. phases with most of the Cr residing in the f.c.c. phase. The addition of 6 at. % Cr not only increased the room temperature ductility, but also completely suppressed the environmental embrittlement observed in the Cr-free alloy at low strain rates. The effects of varying the Al concentration on the microstructures and tensile properties of six two-phase FeNiMnAl alloys with a composition close to Fe30Ni20Mn35Al15 were studied. The increase in f.c.c. volume fraction and f.c.c. lamellar width led to an increase in ductility and a decrease in yield strength. The correlation between the yield stress and f.c.c. lamellar spacing lambda obeyed a Hall-Petch-type relationship, i.e. sigmay=252+0.00027lambda-1, where the units for sigmay and lambda are MPa and meter, respectively. FeNiMnAl alloy with B2 and f.c.c. phases aligned along was reported to show high strength at room temperature. The mechanical properties of Fe 28Ni18Mn33Al21, consisting of (Ni, Al)-enriched B2 and (Fe, Mn)-enriched f.c.c. phases with

  14. The distribution alloying elements in alnico 8 and 9 magnets: Site preference of ternary Ti, Fe, Co, and Ni additions in DO3 Fe3Al, Co3Al, and Ni3Al based intermetallic phases

    DOE PAGESBeta

    Samolyuk, G. D.; Újfalussy, B.; Stocks, G. M.

    2014-11-07

    Recently, interest in alnico magnetic alloys has been rekindled due to their potential to substitute for rare-earth based permanent magnets provided modest improvements in their coercivity can be achieved without loss of saturation magnetization. Recent experimental studies have indicated that atomic and magnetic structure of the two phases (one AlNi-based, the other FeCo-based) that comprise these spinodally decomposed alloy is not as simple as previously thought. A key issue that arises is the distribution of Fe, Co and Ti within the AlNi-based matrix phase. In our paper we report the results of first-principles calculations of the site preference of ternarymore » alloying additions in DO3 Fe3Al, Co3Al and Ni3Al alloys, as models for the aluminide phase. For compound compositions that are Al rich, which corresponds to experimental situation, Ti and Fe are found to occupy the sites, while Co and Ni prefer the sites of the DO3 lattice. Finally, an important finding is that the magnetic moments of transition metals in Fe3Al and Co3Al are ordered ferromagnetically, whereas the Ni3Al were found to be nonmagnetic unless the Fe or Co are added as a ternary element.« less

  15. Tensile properties of cast and mechanically alloyed FeAl with high boron content

    SciTech Connect

    Kim, M.H.; Kwun, S.I.

    1996-08-01

    The FeAl with B2 structure has been considered as a potential structural material for use at elevated temperatures and severe environment. Two major problems with this polycrystalline aluminide are its brittleness through cleavage or grain boundary failure at ambient temperature and rapid strength drop at high temperatures above 750K. In order to expand the use of iron aluminide, these two problems must be overcome. Making a grain size small might be one of the effective ways as the stress distribution is more homogeneous throughout the material. Another method to increase the ductility of iron rich FeAl seems to add small amount of boron. Webb reported that the optimum B content for ambient temperature ductility enhancement was approximately 12 wppm in FeAl(40at%Al). With these points in mind, the authors have tried to modify room and high temperature mechanical properties of FeAl by mechanical alloying. The mechanical alloying is a unique process in that it is an entirely solid state process, permitting fine distribution of insoluble phases and fine grain size material. This paper compares the mechanical properties of the cast and the mechanically alloyed FeAl with B as much as 0.3wt%. The highest B content added in iron rich FeAl was reported to be 0.2wt% up to now.

  16. Catalytic ozonation of petroleum refinery wastewater utilizing Mn-Fe-Cu/Al2O 3 catalyst.

    PubMed

    Chen, Chunmao; Yoza, Brandon A; Wang, Yandan; Wang, Ping; Li, Qing X; Guo, Shaohui; Yan, Guangxu

    2015-04-01

    There is of great interest to develop an economic and high-efficient catalytic ozonation system (COS) for the treatment of biologically refractory wastewaters. Applications of COS require options of commercially feasible catalysts. Experiments in the present study were designed to prepare and investigate a novel manganese-iron-copper oxide-supported alumina-assisted COS (Mn-Fe-Cu/Al2O3-COS) for the pretreatment of petroleum refinery wastewater. The highly dispersed composite metal oxides on the catalyst surface greatly promoted the performance of catalytic ozonation. Hydroxyl radical mediated oxidation is a dominant reaction in Mn-Fe-Cu/Al2O3-COS. Mn-Fe-Cu/Al2O3-COS enhanced COD removal by 32.7% compared with a single ozonation system and by 8-16% compared with Mn-Fe/Al2O3-COS, Mn-Cu/Al2O3-COS, and Fe-Cu/Al2O3-COS. The O/C and H/C ratios of oxygen-containing polar compounds significantly increased after catalytic ozonation, and the biodegradability of petroleum refinery wastewater was significantly improved. This study illustrates potential applications of Mn-Fe-Cu/Al2O3-COS for pretreatment of biologically refractory wastewaters. PMID:25649390

  17. Characteristics of a polycrystalline ZnSe:Fe2+ laser at room temperature

    NASA Astrophysics Data System (ADS)

    Firsov, K. N.; Gavrishchuk, E. M.; Ikonnikov, V. B.; Kazantsev, S. Y.; Kononov, I. G.; Rodin, S. A.; Savin, D. V.; Timofeeva, N. A.

    2015-12-01

    Generation characteristics of laser on polycrystalline ZnSe:Fe2+ samples doped by the diffusion method have been investigated at room temperature under the pumping by an electrodischarge HF laser. With the sample doped from two sides (working surfaces) the obtained generation energy was E=253 mJ with the slope efficiency ηsl=33% and efficiency with respect to the absorbed energy ηabs≍28% at the elliptical shape of the pumping spot of dimension a×b=6.8×7.5 mm. It was established that possibilities of further increase of generation energy on samples of this type by increasing the pumping spot area (at a constant density of the pumping energy) are limited by developing parasitic generation that is inherent in lasers with disk geometry. First investigation results are presented for a laser on the polycrystalline sample produced by the technology capable of providing zero doping component concentration on the surface and a maximal concentration at the centre of the sample (sample with "internal doping"). Prospects are discussed for increasing the generation energy of ZnSe:Fe2+ laser at room temperature by developing multilayer samples on the bases of the doping technique mentioned.

  18. Impact of biogenic nanoscale metals Fe, Cu, Zn and Se on reproductive LV chickens

    NASA Astrophysics Data System (ADS)

    Khiem Nguyen, Quy; Dieu Nguyen, Duy; Kien Nguyen, Van; Thinh Nguyen, Khac; Chau Nguyen, Hoai; Tin Tran, Xuan; Nguyen, Huu Cuong; Tien Phung, Duc

    2015-09-01

    Using biogenic nanoscale metals (Fe, Cu, ZnO, Se) to supplement into diet premix of reproductive LV (a Vietnamese Luong Phuong chicken breed) chickens resulted in certain improvement of poultry farming. The experimental data obtained showed that the farming indices depend mainly on the quantity of nanocrystalline metals which replaced the inorganic mineral component in the feed premix. All four experimental groups with different quantities of the replacement nano component grew and developed normally with livability reaching 91 to 94%, hen’s bodyweight at 38 weeks of age and egg weight ranged from 2.53-2.60 kg/hen and 50.86-51.55 g/egg, respectively. All these farming indices together with laying rate, egg productivity and chick hatchability peaked at group 5 with 25% of nanoscale metals compared to the standard inorganic mineral supplement, while feed consumption was lowest. The results also confirmed that nanocrystalline metals Fe, Cu, ZnO and Se supplemented to chicken feed were able to decrease inorganic minerals in the diet premixes at least four times, allowing animals to more effectively absorb feed minerals, consequently decreasing environmental pollution risks.

  19. Preparation, characterization and antimicrobial applications of Zn-Fe LDH against MRSA.

    PubMed

    Moaty, S A Abdel; Farghali, A A; Khaled, Rehab

    2016-11-01

    Facile and simple processes to get Zn-Fe layered double hydroxide (LDH) with nitrate as the interlayer anion are reported. The method of co-precipitation produced high crystallinity LDH that is marked by XRD, SEM, TEM and FT-IR. Results showed that 99.8% of Cd(+2) removals were at pH11 and 4h. To get the adsorption isotherms, the concentration of metal ions extending from 6 to 18mg/L was utilized. Results supported the Langmuir adsorption model. In contrary, the adsorption process followed the pseudo-second-order reaction kinetics. Interestingly, the prepared LDH shows durable antimicrobial activities against Gram-negative (Proteous vulgaris, Klebsiella pneumoniae, Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus epidermidis, Staphylococcus aureus, Streptococcus pyogenes and MRSA) and fungi (Candida albicans, Aspergillus fumigatus, Geotricumcandidum, and Trichophyton mentagrophytes). The minimum inhibitory concentration (MIC) of Zn-Fe LDH varied from 0.49 to 15.60μg/mL according to the types of microorganisms. The prepared LDH achieved 90% at pH8.50 which is the pH of wastewater and at the same time exhibited durable antimicrobial activities against MRSA, Gram-negative, Gram-positive and fungi. Results have significant implications in the field of bioremediation of water with little cost, simple operation, high productivity and easiness of the equipment. PMID:27524011

  20. Synthesis, characterization and surface modification of ZnCrFeO4 nanoparticles.

    PubMed

    Hamed, Amal; Fitzgerald, Alexander G; Wang, Lijun; Gueorguieva, Mariana; Malik, Ritu; Melzer, Andreas

    2013-04-01

    The aim of this research was to investigate zinc chromium ferrite (ZnCrFeO4) nanoparticles, synthesized using the sol gel technique with nanoparticle size controlled through a two-stage annealing process. Stage one was a low temperature firing which produced low quality nanocrystals with an average size of 15 nm. This was followed by a second firing stage at high temperature which enhanced the crystal quality. The nanoparticles were then coated with a bio-compatible shell to form a stable suspension in the ferrofluid carrier. The resulting nanoparticles were found by electron microscopy, atomic force microscopy and X-ray diffraction studies to have excellent crystal quality. The average size was 8.5 nm. Preliminary cell culture studies indicated the ZnCrFeO4 nanoparticles were non-toxic. The relatively high measured value of the relaxivity r2 showed that the nanoparticle coating was effective in substantially reducing aggregation and enhancing the properties of the nanoparticles associated with contrast enhancement in MRI. PMID:23827616