Structural, magnetic and optical properties of ZnO nanostructures converted from ZnS nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Patel, Prayas Chandra; Ghosh, Surajit; Srivastava, P.C., E-mail: pcsrivastava50@gmail.com

2016-09-15

Graphical abstract: The phase conversion of ZnS to highly crystalline hexagonal ZnO was done by heat treatment. - Highlights: • Phase change of cubic ZnS to hexagonal ZnO via heat treatment. • Band gap was found to decrease with increasing calcinations temperature. • ZnO samples have higher magnetic moment than ZnS. • Blocking Temperature of the samples is well above room temperature. • Maximum negative%MR with saturation value ∼38% was found for sample calcined at 600° C. - Abstract: The present work concentrates on the synthesis of cubic ZnS and hexagonal ZnO semiconducting nanoparticle from same precursor via co-precipitation method. The phase conversion of ZnS to highly crystalline hexagonal ZnO was done by heat treatment. From the analysis of influence of calcination temperature on the structural, optical and vibrational properties of the samples, an optimum temperature was found for the total conversion of ZnS nanoparticles to ZnO. Role of quantum confinement due to finite size is evident from the blue shift of the fundamental absorption in UV–vis spectra only in the ZnS nanoparticles. The semiconducting nature of the prepared samples is confirmed from the UV–vis, PL study and transport study. From the magnetic and transport studies, pure ZnO phase was found to be more prone to magnetic field.

Structural and magnetic properties of Ni-Zn and Ni-Zn-Co ferrites

Energy Technology Data Exchange (ETDEWEB)

Knyazev, A.V., E-mail: knyazevav@gmail.com [N.I. Lobachevsky State University of Nizhni Novgorod, Gagarin Prospekt 23/2, 603950 Nizhni Novgorod (Russian Federation); Zakharchuk, I.; Lähderanta, E. [Lappeenranta University of Technology, P.O. Box 20, FI-53851 Lappeenranta (Finland); Baidakov, K.V.; Knyazeva, S.S. [N.I. Lobachevsky State University of Nizhni Novgorod, Gagarin Prospekt 23/2, 603950 Nizhni Novgorod (Russian Federation); Ladenkov, I.V. [Joint-stock Company “Research and Production Company “Salut”, Nizhni Novgorod (Russian Federation)

2017-08-01

Highlights: • Ni-Zn and Ni-Zn-Co ferrite powders were prepared by the solid-state reaction at 1073 K. • The room temperature saturation magnetizations are 59.7 emu/g for Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and 57.1 emu/g for Ni{sub 0.5}Zn{sub 0.3}Co{sub 0.2}Fe{sub 2}O{sub 4}. • The coercivity of the samples is found to be much larger than that of bulk ferrites and increases with Co introduction. • The temperature dependences of magnetization exhibit large spin frustration and spin-glass-like behavior. - Abstract: Ni-Zn and Ni-Zn-Co ferrite powders with nominal compositions Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and Ni{sub 0.5}Zn{sub 0.3}Co{sub 0.2}Fe{sub 2}O{sub 4} were prepared by the solid-state reaction synthesis with periodic regrinding during the calcination at 1073 K. The structure of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and Ni{sub 0.5}Zn{sub 0.3}Co{sub 0.2}Fe{sub 2}O{sub 4} was refined assuming space group F d-3m. Scanning electron microscopy revealed the average sizes of the crystalline ferrite particles are 130–630 nm for Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and 140–350 nm for Ni{sub 0.5}Zn{sub 0.3}Co{sub 0.2}Fe{sub 2}O{sub 4}. The room temperature saturation magnetizations are 59.7 emu/g for Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and 57.1 emu/g for Ni{sub 0.5}Zn{sub 0.3}Co{sub 0.2}Fe{sub 2}O{sub 4}. The coercivity of the samples is found to be much larger than that of bulk ferrites and increases with Co introduction. The Curie temperature tends to increase upon Zn substitution by Co, as well. The temperature dependences of magnetization measured using zero-field cooled and field cooled protocols exhibit large spin frustration and spin-glass-like behavior.

Cathodoluminescence of GaN diped with Zn in the process of epitaxial growth and by the method of ionic implantation

International Nuclear Information System (INIS)

Khasanov, I.Sh.; Gippius, A.A.; Kuznetsov, A.V.; Petrov, M.N.; Sletov, M.M.

1984-01-01

The cathodoluminescence (CL) method was used to investigate the epitaxial GaN layers doped with Zn both in the process of growth and by the method of ionic implantation for the purpose of clarifying the effect of doping technique on impurity luminescence. It was shown that (2-3)x10 18 cm -3 concentration is optimal with respect to intensity of impurity ''blue'' luminescence for gallium nitride doped with Zn. The intensity of GaN ''blue'' luminescence during Zn ionic implantation is several times lower as compared with doping in the process of growth. This is related to incomplete optical activation of impurity atoms in the process of postimplantation thermal annealing. Increase of zinc concentration above optimal during ionic implantation intensifies crystal lattice disordering, which is supported by intensification of 1.7 eV cathodoluminescence band in spectra conditioned by defects

In situ direct observation of photocorrosion in ZnO crystals in ionic liquid using a laser-equipped high-voltage electron microscope

Directory of Open Access Journals (Sweden)

J. Ishioka

2017-03-01

Full Text Available ZnO photocatalysts in water react with environmental water molecules and corrode under illumination. ZnO nanorods in water can also grow because of water splitting induced by UV irradiation. To investigate their morphological behavior caused by crystal growth and corrosion, here we developed a new laser-equipped high-voltage electron microscope and observed crystal ZnO nanorods immersed in ionic liquid. Exposing the specimen holder to a laser with a wavelength of 325 nm, we observed the photocorrosion in situ at the atomic scale for the first time. This experiment revealed that Zn and O atoms near the interface between the ZnO nanorods and the ionic liquid tended to dissolve into the liquid. The polarity and facet of the nanorods were strongly related to photocorrosion and crystal growth.

Magnetic ionic liquids: synthesis and characterization

International Nuclear Information System (INIS)

Medeiros, Anderson M.M.S.; Parize, Alexandre L.; Oliveira, Vanda M.; Neto, Brenno A.D.; Rubim, Joel C.

2010-01-01

The synthesis of magnetic ionic liquids (MILs) based on the stable dispersions of magnetic nanoparticles (MNPs) of γ-Fe 2 O 3 , Fe 3 O 4 , and CoFe 2 O 4 in the ionic liquid 1-n-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMI.NTf 2 ) is reported. The MNPs were obtained by the coprecipitation method. The surface of the α-Fe 2 O 3 , Fe 3 O 4 , and CoFe 2 O 4 MNPs with mean sizes (XRD) of 9.3, 12.3, and 11.0 nm, respectively were functionalized by 1-n-butyl-3-(3'-trimethoxypropylsilane)- imidazolium chloride. The non functionalized and functionalized MNPs were further characterized by Raman, FTIR-ATR, and FTNIR spectroscopy and by TGA. The stability of the MILs was assigned to the formation of at least one monolayer of the surface modifier agent that mimics the structure of the BMI.NTf 2 IL. (author)

Magnetic phase transitions and large magnetic entropy change with a wide temperature span in HoZn

Energy Technology Data Exchange (ETDEWEB)

Li, Lingwei, E-mail: wei0396@hotmail.com [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30, D-48149 Münster (Germany); Yuan, Ye [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Ion Beam Physics and Materials Research, P.O. Box 510119, 01314 Dresden (Germany); Zhang, Yikun [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Pöttgen, Rainer [Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30, D-48149 Münster (Germany); Zhou, Shengqiang [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Ion Beam Physics and Materials Research, P.O. Box 510119, 01314 Dresden (Germany)

2015-09-15

Highlights: • Magnetic phase transitions and magnetocaloric effect in HoZn were studied. • The critical properties of HoZn were systematically investigated. • The obtained critical exponents are satisfied with scaling theory. • A large reversible magnetocaloric effect in HoZn was observed. • HoZn could be a promising candidate for magnetic refrigeration. - Abstract: CsCl-type HoZn undergoes two successive magnetic phase transitions: (i) paramagnetic to ferromagnetic (FM) at T{sub C} ∼ 72 K and (ii) a spin reorientation (SR) at T{sub SR} ∼ 26 K. Magnetization and modified Arrott plots indicate that HoZn undergoes a second-order magnetic phase transition around T{sub C}. The obtained critical exponents have some small deviations from the mean-field theory, indicating a short range or a local magnetic interaction which is properly related to the coexistence of FM and SR transitions at low temperature. Two successive magnetic transitions in HoZn induce one broad pronounced peak together with a shoulder in the temperature dependence of the magnetic entropy change −ΔS{sub M}(T) curves, resulting in a wide temperature range with a large relative cooling power (RCP). For a field change of 0–7 T, the maximum value of −ΔS{sub M} is 15.2 J/kg K around T{sub C} with a large RCP value of 1124 J/kg. The large reversible magnetocaloric effect (MCE) and RC indicate that HoZn is a good candidate for active magnetic refrigeration.

Structural and magnetic Properties of TbZn-substituted calcium barium M-type nano-structured hexa-ferrites

Energy Technology Data Exchange (ETDEWEB)

Khan, Hasan M. [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Department of Electronics, University of York, York YO10 5DD (United Kingdom); Islam, M.U., E-mail: dr.misbahulislam@bzu.edu.pk [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Xu, Yongbing [Department of Electronics, University of York, York YO10 5DD (United Kingdom); Nanjing–York International Centre of Spintronics and Nano-Engineering, Nanjing University, Nanjing 210093 (China); Asif Iqbal, M. [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); National University of Science and Technology, College of E and ME, Islamabad (Pakistan); Ali, Irshad [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan)

2014-03-15

Highlights: • Tb–Zn substituted Ca{sub 0.5}Ba{sub 0.5}Fe{sub 12}O{sub 19} samples exhibit single magnetoplumbite phase. • Lattice parameters a and c have increasing values. • Coercivity can be tuned at lower substitution level • Crystallites size was found in the range 18–25 nm by TEM and by Scherrer formula. • These hexa-ferrites are suitable for microwave devices and magnetic recording media. -- Abstract: Effect of TbZn substitution on the structural and magnetic properties of Ca{sub 0.5}Ba{sub 0.5−x}Tb{sub x}Zn{sub y}Fe{sub 12−y}O{sub 19}, (x = 0.00–0.10; y = 0.00–1.00) ferrites prepared by sol–gel auto combustion is reported. The synthesized samples were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Vibrating Sample magnetometery. The X-ray diffraction analysis confirmed single phase M-type hexa-ferrite structure. The lattice parameters were found to increase as TbZn contents increases, which is attributed to the ionic sizes of the implicated cations. The TbZn seems to be completely soluble in the lattice. The results of scanning electron microscopy and transmission electron microscopy shows that the grain size decreases with increase of TbZn substitution. The coercivity values (1277–2025 Oe) of all samples lies in the range of M-type hexa-ferrite and indicate that an increase of anisotropy was achieved by substitution of TbZn, while the size of nanoparticles was drastically reduced between 18 and 25 nm. The increased anisotropy and fine particle size are useful for many applications, such as improving signal noise ratio of recording devices.

Structural, optical, XPS and magnetic properties of Zn particles capped by ZnO nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Morozov, Iu.G., E-mail: yugmor@hotmail.com [Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Academician Osipyan Street 8, Chernogolovka, Moscow Region 142432 (Russian Federation); Belousova, O.V. [Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Academician Osipyan Street 8, Chernogolovka, Moscow Region 142432 (Russian Federation); Ortega, D., E-mail: daniel.ortega@imdea.org [Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Cantoblanco 28049, Madrid (Spain); Mafina, M.-K., E-mail: m.k.mafina@qmul.ac.uk [School of Engineering and Materials Science, Queen Mary University of London, Mile End, Eng, 231, London E1 4NS (United Kingdom); Kuznetcov, M.V., E-mail: maxim1968@mail.ru [Department of Chemistry, Materials Chemistry Research Centre, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)

2015-06-05

Highlights: • Levitation-jet aerosol synthesis of Zn particles capped by ZnO nanoparticles (NPs). • TEM, XRD, UV–vis, FT-IR, Raman, XPS and magnetic characterization of the NPs. • Correlation between unit-cell volume of crystal lattice and maximum magnetization. - Abstract: Spherical zinc particles ranging from 42 to 760 nm in average size and capped with plate-like zinc oxide particles of 10–30 nm in sizes have been prepared by levitation-jet aerosol synthesis through condensation of zinc vapor in an inert/oxidizer gas flow. The nanoparticles have been characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), BET measurements, ultra violet visible (UV–vis) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, X-ray electron spectroscopy (XPS), superconducting quantum interference device (SQUID), and vibrating-sample magnetometer (VSM). Magnetic and XRD data indicate that the observed ferromagnetic ordering related to the changes in unit-cell volume of Zn in the Zn/ZnO interface of the nanoparticles. These results are in good correlation with the optical measurements data.

Magnetic behavior of Co–Mn co-doped ZnO nanoparticles

International Nuclear Information System (INIS)

Li, Hengda; Liu, Xinzhong; Zheng, Zhigong

2014-01-01

Here, we report on systematic studies of the magnetic properties of Co and Mn co-doped ZnO nanoparticles prepared by a sol–gel technique. The effect of the concentration of the doping ions on the magnetic properties of Co and Mn co-doped ZnO nanoparticles is presented. X-ray diffraction characterizations (XRD) of co-doped ZnO nanoparticles are all wurtzite structure. The Zn 0.96 Co 0.02 Mn 0.02 O nanoparticles and Zn 0.94 Co 0.02 Mn 0.04 O nanoparticles display ferromagnetic behavior at room temperature. Superconducting quantum interference device (SQUID) magnetometer figures show that with the concentration of the Mn ions increased, the saturation magnetic moment (M s ) increased, and the magnetic is probably due to the co-doping of the Mn ions. Our results demonstrate that the Mn ions doping concentration play an important role in the ferromagnetic properties of Co–Mn co-doped ZnO nanoparticles at room temperature. - Highlights: • The effect of the doping ions on the magnetic properties is presented. • The magnetic is probably due to the co-doping of the Mn ions. • The Mn ions concentration play an important role in the ferromagnetic properties

Synthesis and magnetic properties of Zn Spinel ceramics

Czech Academy of Sciences Publication Activity Database

Huber, Š.; Sofer, Z.; Nádherný, L.; Jankovský, O.; Šimek, P.; Sedmidubský, D.; Maryško, Miroslav

2013-01-01

Roč. 57, č. 2 (2013), s. 162-166 ISSN 0862-5468 R&D Projects: GA ČR GA13-17538S; GA MŠk(CZ) 7AMB12FR019 Institutional support: RVO:68378271 Keywords : Zn spinel * synthesis * magnetic properties * antiferromagnet * bulk ZnO Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.434, year: 2013

Characterization of nanostructures of ZnO and ZnMnO films deposited by successive ionic layer adsorption and reaction method

Energy Technology Data Exchange (ETDEWEB)

Jimenez-Garcia, F.N. [Departamento de Fisica y Matematicas, Universidad Autonoma de Manizales, Antigua Estacion del Ferrocarril, Manizales, Caldas (Colombia); Departamento de Fisica y Quimica, Universidad Nacional de Colombia, Sede Manizales, Campus la Nubia, Manizales, Caldas (Colombia); Espinosa-Arbelaez, D.G. [Departamento de Nanotecnologia, Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, Blv. Juriquilla 3001, Juriquilla, Queretaro, C.P. 76230 (Mexico); Posgrado en Ciencia e Ingenieria Materiales, Instituto de Investigacion en Materiales, Universidad Nacional Autonoma de Mexico, Mexico DF (Mexico); Vargas-Hernandez, C. [Departamento de Fisica y Quimica, Universidad Nacional de Colombia, Sede Manizales, Campus la Nubia, Manizales, Caldas (Colombia); Real, A. del [Departamento de Nanotecnologia, Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, Blv. Juriquilla 3001, Juriquilla, Queretaro, C.P. 76230 (Mexico); Rodriguez-Garcia, M.E., E-mail: marioga@fata.unam.mx [Departamento de Nanotecnologia, Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, Blv. Juriquilla 3001, Juriquilla, Queretaro, C.P. 76230 (Mexico)

2011-09-01

ZnO and ZnMnO thin films were obtained by the successive ionic layer adsorption and reaction (SILAR) method. All thin films were deposited on glass microscope slide. A precursor solution of 0.1 M of ZnCl{sub 2} complexed with ammonium hydroxide and water close to boiling point (92 deg. C) as a second solution was used for the ZnO films. An uncomplexed bath comprised of 0.1 M ZnCl{sub 2}, 0.1 M MnCl{sub 2,} and a second solution of 0.1 ml of NH{sub 4}OH with water close to boiling point was used for the ZnMnO films. The film samples were deposited by the SILAR method and annealed at 200 deg. C for 15 min. These samples were characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (EDS), and Atomic Force Microscope. Atomic absorption was used to determine quantitatively the amount of Mn incorporated into the films. According to the XRD patterns these films were polycrystalline with wurtzite hexagonal structure. The morphology of the ZnO films constituted by rice-like and flower-like structures changed significantly to nanosheet structures with the Mn incorporation. The Mn inclusion in a ZnO structure was less than 4% according to the results from EDS, XRD, and atomic absorption.

Characterization of nanostructures of ZnO and ZnMnO films deposited by successive ionic layer adsorption and reaction method

International Nuclear Information System (INIS)

Jimenez-Garcia, F.N.; Espinosa-Arbelaez, D.G.; Vargas-Hernandez, C.; Real, A. del; Rodriguez-Garcia, M.E.

2011-01-01

ZnO and ZnMnO thin films were obtained by the successive ionic layer adsorption and reaction (SILAR) method. All thin films were deposited on glass microscope slide. A precursor solution of 0.1 M of ZnCl 2 complexed with ammonium hydroxide and water close to boiling point (92 deg. C) as a second solution was used for the ZnO films. An uncomplexed bath comprised of 0.1 M ZnCl 2 , 0.1 M MnCl 2, and a second solution of 0.1 ml of NH 4 OH with water close to boiling point was used for the ZnMnO films. The film samples were deposited by the SILAR method and annealed at 200 deg. C for 15 min. These samples were characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (EDS), and Atomic Force Microscope. Atomic absorption was used to determine quantitatively the amount of Mn incorporated into the films. According to the XRD patterns these films were polycrystalline with wurtzite hexagonal structure. The morphology of the ZnO films constituted by rice-like and flower-like structures changed significantly to nanosheet structures with the Mn incorporation. The Mn inclusion in a ZnO structure was less than 4% according to the results from EDS, XRD, and atomic absorption.

Magnetic susceptibility of MnZn and NiZn soft ferrites using Laplace transform and the Routh-Hurwitz criterion

International Nuclear Information System (INIS)

Fano, Walter Gustavo; Boggi, Silvina; Razzitte, Adrian Cesar

2011-01-01

This paper is devoted to study the Routh-Hurwitz stability criterion from the MnZn and NiZn soft ferrites using a phenomenological model with the gyromagnetic spin contribution and domain wall contribution. The magnetodynamic equation and the harmonic oscillator equation have been used to obtain the domain walls and the spin contribution of the magnetic susceptibility. The ferrite materials have been considered as linear, time invariant, isotropic and homogeneous, and the magnetization vector is proportional to the magnetic field vector. The resulting expression of the magnetization in time domain of both ferrites under study has been obtained by mean of the inverse Laplace transformation applying the residue method. The poles of the magnetic susceptibility have negative real parts, which ensures that the response decays exponentially to zero as the time increase. The degree of the numerator's polynomial of the magnetic susceptibility is less than the degree of denominator's polynomial in the magnetic susceptibility function: and the poles are located in the half left s-plane. Then the system is bounded-input, bounded-output (BIBO), and the results agree with the Routh-Hurwitz stability criterion for the MnZn and NiZn soft ferrites. - Research Highlights: → Laplace transform of the magnetic susceptibility of the MnZn and NiZn soft ferrites. → Routh-Hurwitz stability criterion of magnetic materials. → Bode plot of magnetic susceptibility. → Inverse Laplace transform using residue theorem.

Synthesis, characterization and magnetic properties of monodisperse Ni, Zn-ferrite nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Kumar, Sanjeev, E-mail: sanjeevkumar.dubey2@gmail.com [University of Petroleum and Energy Studies, Dehradun, Uttarakhand (India); Kumar, Pankaj [University of Petroleum and Energy Studies, Dehradun, Uttarakhand (India); Singh, Vaishali [University School of Basic and Applied Science (India); Kumar Mandal, Uttam [University of Chemical Technology, GGS Indraprastha University, Sector 16, Dwarka, Delhi 110403 (India); Kumar Kotnala, Ravinder [National Physical laboratory, New Delhi 110012 (India)

2015-04-01

Synthesization of monodisperse Ni, Zn-ferrite (Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4}, x=1, 0.8, 0.6, 0.5, 0.4, 0.2, 0.0) nanocrystals has been achieved by the inverse microemulsion method using CTAB as surfactant and kerosene as an oil phase. The detailed characterization of the synthesized nanocrystals and measurement of the magnetic properties has been done by techniques like X-ray diffraction (XRD), field emission transmission electron microscopy (FETEM), Fourier transform infrared spectroscopy (FITR) and Vibrating Sample Magnetometer (VSM) respectively. The relationship between the structure and composition of the nanocrystals with magnetic properties has been investigated. The nanocrystals size is found to be in the range 1–5 nm. The effect of Zn substitution on size and magnetic properties has been studied. It has been observed that magnetism changed from ferromagnetic at X= 0 to super paramagnetic to paramagnetic at X=1 as Zn concentration increased. The Curie temperature is found to decrease with an increase in Zn concentration. - Highlights: • Reverse microemulsion route is very facile route for synthesis of Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} ferrite. • Presence of Zn changes the structural and magnetic properties of the Zn substituted NiFe{sub 2}O{sub 4.} • The lattice constant increases with the increase in Zn substitution. • The curie temperature decreases with Zn concentration appreciably. • Magnetic behavior varies from ferromagnetic at x=0 to superparamagnetic to paramagnetic at x=1.

Ab initio studies of magnetic anisotropy energy in highly Co-doped ZnO

Energy Technology Data Exchange (ETDEWEB)

Łusakowski, A., E-mail: lusak@ifpan.edu.pl [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, PL-02668 Warsaw (Poland); Szuszkiewicz, W. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, PL-02668 Warsaw (Poland); Faculty of Mathematics and Natural Sciences, University of Rzeszów, ul. S. Pigonia 1, PL-35959 Rzeszów (Poland)

2017-03-15

Density functional theory (DFT) calculations of the energy of magnetic anisotropy for diluted magnetic semiconductor (Zn,Co)O were performed using OpenMX package with fully relativistic pseudopotentials. The analysis of the band spin-orbit interaction and the magnetic ion's surrounding on magnetic anisotropy have been provided. As a result, the calculations show that the magnetic anisotropy in (Zn,Co)O solid solution, mainly of the single ion anisotropy type has been caused by Co ions. - Highlights: • The magnetic anisotropy in (Zn,Co)O is mainly due to anisotropy of single cobalt ion. • The magnetic anisotropy of (Zn,Co)O strongly depends on the nearest neighborhood of magnetic ion including local lattice deformations. • For (Zn,Co)O the energy of magnetic anisotropy is described by second order terms in magnetization.

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

International Nuclear Information System (INIS)

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

2016-01-01

We investigated composites that have been prepared from FeSi powders covered with MnZnFe 2 O 4 (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. - Highlights: • Successful preparation of soft magnetic composite FeSi/MnZnFe 2 O 4 . • Study of the complex magnetic permeability. • Comparison of different compositions of prepared SMC's. • Determination of parts of magnetic losses.

ZnS nanostructured thin-films deposited by successive ionic layer adsorption and reaction

Science.gov (United States)

Deshmukh, S. G.; Jariwala, Akshay; Agarwal, Anubha; Patel, Chetna; Panchal, A. K.; Kheraj, Vipul

2016-04-01

ZnS thin films were grown on glass substrate using successive ionic layer adsorption and reaction (SILAR) technique at room temperature. Aqueous solutions of ZnCl2 and Na2S were used as precursors. The X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Raman spectroscopy and optical absorption measurements were applied to study the structural, surface morphology and optical properties of as-deposited ZnS thin films. The X-ray diffraction profiles revealed that ZnS thin films consist of crystalline grains with cubic phase. Spherical nano grains of random size and well covered on the glass substrate were observed from FESEM. The average grain size were found to be 77 nm, 100 nm and 124 nm for 20 cycles, 40 cycles and 60 cycles samples respectively. For 60 cycle sample, Raman spectra show two prominent peaks at 554 cm-1 and 1094 cm-1. The optical band gap values were found to be 3.76 eV, 3.72 eV and 3.67 eV for 20 cycle, 40 cycle and 60 cycle samples respectively.

Magnetic graphene oxide modified by imidazole-based ionic liquids for the magnetic-based solid-phase extraction of polysaccharides from brown alga.

Science.gov (United States)

Wang, Xiaoqin; Li, Guizhen; Row, Kyung Ho

2017-08-01

Magnetic graphene oxide was modified by four imidazole-based ionic liquids to synthesize materials for the extraction of polysaccharides by magnetic solid-phase extraction. Fucoidan and laminarin were chosen as the representative polysaccharides owing to their excellent pharmaceutical value and availability. Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, and thermogravimetric analysis were applied to characterize the synthesized materials. Single-factor experiments showed that the extraction efficiency of polysaccharides was affected by the amount of ionic liquids for modification, solid-liquid ratio of brown alga and ethanol, the stirring time of brown alga and ionic liquid-modified magnetic graphene oxide materials, and amount of 1-(3-aminopropyl)imidazole chloride modified magnetic graphene oxide materials added to the brown alga sample solution. The results indicated that 1-(3-aminopropyl)imidazole chloride modified magnetic graphene oxide possessed better extraction ability than graphene oxide, magnetic graphene oxide, and other three ionic-liquid-modified magnetic graphene oxide materials. The highest extraction recoveries of fucoidan and laminarin extracted by 1-(3-aminopropyl)imidazole chloride modified magnetic graphene oxide were 93.3 and 87.2%, respectively. In addition, solid materials could be separated and reused easily owing to their magnetic properties. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Doping induced magnetism in Co-ZnS nanoparticles

International Nuclear Information System (INIS)

Sambasivam, S.; Paul Joseph, D.; Lin, J.G.; Venkateswaran, C.

2009-01-01

Zn 1-x Co x S nanoparticles with x=0, 0.1, 0.2, and 0.3 were synthesized by the co-precipitation method using thiophenol as capping agent. The effect of Co doping on the structural, optical and magnetic properties are investigated. The X-ray diffraction patterns show single phase with cubic structure and the images of Transmission Electron Microscopy indicate an average particle size of 39 nm. Significant blue shift in the optical absorbing band edge was observed with increasing Co doping. In the Co doped samples, room-temperature (RT) magnetic hysteresis is observed and the magnetization reduces with increasing Co content. However, these samples show paramagnetic resonance instead of ferromagnetic resonance at both 300 and 80 K, suggesting that the origin of RT magnetization in these Zn 1-x Co x S nanoparticles involves with the frustration of antiferromagnetic interactions. - Graphical abstract: Figure shows the magnetization data of Zn 1-x Co x S (0.1≤x≤0.3) nanoparticles annealed at 573 K/2 h in vacuum and measured at 300 K. This interesting feature of systematic reduction in magnetization may be due to introduction of antiferromagnetic ordering with increasing 'Co' concentration which may be due to competition between the antiferromagnetic and ferromagnetic ordering within the sample. One could also observe the exchange bias effect which is an interface interaction observed in a ferromagnetic-antiferromagnetic mixture. The exchange bias field (loop shift) towards negative field was around 63 Oe for the Zn 1-x Co x S (0.1≤x≤0.3) nanoparticles.

Investigation of intrinsic defect magnetic properties in wurtzite ZnO materials

Science.gov (United States)

Fedorov, A. S.; Visotin, M. A.; Kholtobina, A. S.; Kuzubov, A. A.; Mikhaleva, N. S.; Hsu, Hua Shu

2017-10-01

Theoretical and experimental investigations of the ferromagnetism induced by intrinsic defects inside wurtzite zinc oxide structures are performed using magnetic field-dependent circular dichroism (MCD-H), direct magnetization measurement (M-H) by superconducting quantum interference device (SQUID) as well as by generalized gradient density functional theory (GGA-DFT). To investigate localized magnetic moments of bulk material intrinsic defects - vacancies, interstitial atoms and Frenkel defects, various-size periodic supercells are calculated. It is shown that oxygen interstitial atoms (Oi) or zinc vacancies (Znv) generate magnetic moments of 1,98 и 1,26 μB respectively, however, the magnitudes are significantly reduced when the distance between defects increases. At the same time, the magnetic moments of oxygen Frenkel defects are large ( 1.5-1.8 μB) and do not depend on the distance between the defects. It is shown that the origin of the induced ferromagnetism in bulk ZnO is the extra spin density on the oxygen atoms nearest to the defect. Also dependence of the magnetization of ZnO (10 1 ̅ 0) and (0001) thin films on the positions of Oi and Znv in subsurface layers were investigated and it is shown that the magnetic moments of both defects are significantly different from the values inside bulk material. In order to check theoretical results regarding the defect induced ferromagnetism in ZnO, two thin films doped by carbon (C) and having Zn interstitials and oxygen vacancies were prepared and annealed in vacuum and air, respectively. According to the MCD-H and M-H measurements, the film, which was annealed in air, exhibits a ferromagnetic behavior, while the other does not. One can assume annealing of ZnO in vacuum should create oxygen vacancies or Zn interstitial atoms. At that annealing of the second C:ZnO film in air leads to essential magnetization, probably by annihilation of oxygen vacancies, formation of interstitial oxygen atoms or zinc vacancies

Magnetically separable core–shell ZnFe_2O_4@ZnO nanoparticles for visible light photodegradation of methyl orange

International Nuclear Information System (INIS)

Kulkarni, Suresh D.; Kumbar, Sagar; Menon, Samvit G.; Choudhari, K.S.; Santhosh, C.

2016-01-01

Highlights: • Phase pure, magnetic ZnFe_2O_4@ZnO nanoparticles synthesized with excellent yield. • ZnFe_2O_4@ZnO displayed higher UV photocatalytic efficiency than ZnO nanoparticles. • First report on visible light photodegradation of methyl orange by ZnFe_2O_4@ZnO. • Excellent reusability of ZnFe_2O_4@ZnO nanoparticles observed for azo dye removal. - Abstract: Visible light photodegradation of aqueous methyl orange using magnetically separable core–shell ZnFe_2O_4@ZnO nanoparticles is reported. A combination of low temperature (190 °C) microwave synthesis and hydrothermal method were used to prepare phase pure material with excellent yield (95%). The magnetic separability, surface area of 41 m"2/g and visible light absorption make ZnFe_2O_4@ZnO nanoparticles a good solar photocatalyst. ZnFe_2O_4@ZnO displayed greater UV photocatalytic efficiency than ZnO owing to the generation of large number of electron-hole pairs. Visible light photodegradation of MO using ZnFe_2O_4@ZnO nanoparticles is reported for the first time. Higher first order rate constants under both UV and visible light for core-shell nanoparticles suggested their superiority over its individual oxides. The ZnFe_2O_4@ZnO showed excellent reusability with high photocatalytic efficiencies suggesting its suitability for solar photocatalytic applications.

Defect-induced magnetic order in pure ZnO films

Science.gov (United States)

Khalid, M.; Ziese, M.; Setzer, A.; Esquinazi, P.; Lorenz, M.; Hochmuth, H.; Grundmann, M.; Spemann, D.; Butz, T.; Brauer, G.; Anwand, W.; Fischer, G.; Adeagbo, W. A.; Hergert, W.; Ernst, A.

2009-07-01

We have investigated the magnetic properties of pure ZnO thin films grown under N2 pressure on a -, c -, and r -plane Al2O3 substrates by pulsed-laser deposition. The substrate temperature and the N2 pressure were varied from room temperature to 570°C and from 0.007 to 1.0 mbar, respectively. The magnetic properties of bare substrates and ZnO films were investigated by SQUID magnetometry. ZnO films grown on c - and a -plane Al2O3 substrates did not show significant ferromagnetism. However, ZnO films grown on r -plane Al2O3 showed reproducible ferromagnetism at 300 K when grown at 300-400°C and 0.1-1.0 mbar N2 pressure. Positron annihilation spectroscopy measurements as well as density-functional theory calculations suggest that the ferromagnetism in ZnO films is related to Zn vacancies.

Bound magnetic polaron in Zn-rich cobalt-doped ZnSe nanowires

Science.gov (United States)

Hou, Lipeng; Pan, Longfei; Liang, Bianbian; Liu, Yuting; Zhang, Li; Bukhtiar, Arfan; Shi, Lijie; Liu, Ruibin; Zou, Bingsuo

2018-02-01

The micro-luminescence spectra of the diluted magnetic semiconductor (DMS) can reflect the spin-exciton interaction and related relaxation process. Here the micro-photoluminescence (micro-PL) spectra and PL lifetime measurements have been done on an individual ferromagnetic (FM)-coupled cobalt (Co) doped zinc selenide (ZnSe) nanowire. There occurs a double-peak profile in its near bandedge emission spectrum: the first peak is from free exciton (FX) and the second comes from magnetic polaron (MP). In their temperature dependent PL spectra, the MP emission peak demonstrates obviously temperature-independent behavior, in contrast to the behaviors of FX and reported exciton MP in nanobelt. It is found that in this Co(II) doped ZnSe nanowires, this MP’s temperature-independent emission is related to the coupling between exciton and a FM nanocluster (↑↑↓). The nanocluster is likely due to the interaction of Se vacancies of the wide bandgap semiconductors with the antiferromagnetic (AFM) arrangement transition metal (TM) ions in these Se-deficient Co doped ZnSe nanowires. These results reflect that the AFM coupling TM ions pair can give rise to FM behavior with the involvement of positive charge defect, also indicating that the micro-luminescence detection can be used to study the magnetic coupling in DMS.

Optical and magnetic properties of ZnO/ZnFe{sub 2}O{sub 4} nanocomposite

Energy Technology Data Exchange (ETDEWEB)

Zamiri, Reza, E-mail: reza.zamiri@tdt.edu.vn [Department for Management of Science and Technology Development, Ton Duc Thang University, Ho Chi Minh City (Viet Nam); Faculty of Electrical & Electronics Engineering, Ton Duc Thang University, Ho Chi Minh City (Viet Nam); Salehizadeh, S.A. [Physics Department (I3N), University of Aveiro, Campus Universitario de Santiago, Aveiro (Portugal); Ahangar, Hossein Abbastabar [Department of Chemistry, Faculty of Sciences, Najafabad Branch, Islamic Azad University, Najafabad (Iran, Islamic Republic of); Shabani, Mehdi; Rebelo, Avito [Department of Materials and Ceramic Engineering (DEMaC), University of Aveiro, Campus Santiago, Aveiro, 3810-193 (Portugal); Suresh Kumar, J.; Soares, M.J.; Valente, M.A. [Physics Department (I3N), University of Aveiro, Campus Universitario de Santiago, Aveiro (Portugal); Ferreira, J.M.F. [Department of Materials and Ceramic Engineering (DEMaC), University of Aveiro, Campus Santiago, Aveiro, 3810-193 (Portugal)

2017-05-01

ZnO/ZnFe{sub 2}O{sub 4} nanocomposite was prepared by a simple and low cost chemical precipitation method. The prepared composite was characterized by X-ray diffraction (XRD), energy-dispersive X-ray (EDX), Raman and Fourier Transform infrared spectroscopy (FTIR). The morphology of the prepared sample was studied by scanning electron microscopy (SEM). Photoluminescence (PL) emission of the sample has been investigated at different temperatures (10–300 K) in order to determine the effect of temperature on emission properties of the prepared composite. It was found that at low temperature, the samples show stronger emissions than those at room temperature. Magnetic properties of ZnO/ZnFe{sub 2}O{sub 4} nanocomposite was discussed in temperature range of 5–300 K using VSM measurement. The effective anisotropy constant K{sub eff}, extracted from the magnetization vs. magnetic field, M(B), experimental curve obtained at 5 K and using the law of saturation magnetization, was found to be 2.3 × 10{sup 6} erg/cm{sup 3}. The high value of anisotropy constant is attributed to the existence of uncompensated surface spin in our sample as well as the magnetocrystalline contribution (which depends on the inversion degree in ZnFe{sub 2}O{sub 4}). By using of a modified Langevin equation, the contribution of the surface spins was quantitatively calculated in different temperature higher than T{sub B}. It was found that as the temperature increases from 100 K to 300 K, the surface spins contribution in the total magnetization increases from 44% to 68%. - Highlights: • Fabrication of ZnO/ZnFe{sub 2}O{sub 4} nanocomposite by a simple and low cost method. • The sample show stronger emissions at low temperature than at room temperature. • The effective anisotropy constant K{sub eff}, was found to be 2.3 × 10{sup 6} erg/cm{sup 3}. • By increasing temperature from 100 K to 300 K, the surface spins contribution increases.

Nonstoichiometric Zn Ferrite and ZnFe2O4/Fe2O3 Composite Spheres: Preparation, Magnetic Properties, and Chromium Removal

Science.gov (United States)

Hang, Chun-Liang; Yang, Li-Xia; Sun, Chang-Mei; Liang, Ying

2018-03-01

Monodisperse and porous nonstoichiometric Zn ferrite can be prepared by a solvothermal method. Such non-Zn ferrite was used to be the precursor for synthesis of ZnFe2O4/Fe2O3 composite via calcination at 600°C for 3 h in air. X-ray powder diffractometer (XRD) and Energy Dispersive Spectrometer (EDS) proved the nonstoichiometry of Zn ferrite synthesized by solvothermal method and the formation of ZnFe2O4/Fe2O3 composite via calcination. TEM image showed that non-Zn ferrite spheres with wormlike nanopore structure were made of primary nanocrystals. BET surface area of non-Zn ferrite was much higher than that of ZnFe2O4/Fe2O3 composite. Saturation magnetization of non-Zn ferrites was significantly higher than that of ZnFe2O4/Fe2O3 composites. Calcination of non-Zn ferrite resulted in the formation of large amount of non-magnetic Fe2O3,which caused a low magnetization of composite. Because of higher BET surface area and higher saturation magnetization, non-Zn ferrite presented better Cr6+ adsorption property than ZnFe2O4/Fe2O3 composites.

ZnS nanostructured thin-films deposited by successive ionic layer adsorption and reaction

Energy Technology Data Exchange (ETDEWEB)

Deshmukh, S. G., E-mail: deshmukhpradyumn@gmail.com; Jariwala, Akshay; Agarwal, Anubha; Patel, Chetna; Kheraj, Vipul, E-mail: vipulkheraj@gmail.com [Department of Applied Physics, Sardar Vallabhbhai National Institute of Technology, Ichchhanath, Surat (India); Panchal, A. K. [Department of Electrical Engineering, Sardar Vallabhbhai National Institute of Technology, Ichchhanath, Surat (India)

2016-04-13

ZnS thin films were grown on glass substrate using successive ionic layer adsorption and reaction (SILAR) technique at room temperature. Aqueous solutions of ZnCl{sub 2} and Na{sub 2}S were used as precursors. The X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Raman spectroscopy and optical absorption measurements were applied to study the structural, surface morphology and optical properties of as-deposited ZnS thin films. The X-ray diffraction profiles revealed that ZnS thin films consist of crystalline grains with cubic phase. Spherical nano grains of random size and well covered on the glass substrate were observed from FESEM. The average grain size were found to be 77 nm, 100 nm and 124 nm for 20 cycles, 40 cycles and 60 cycles samples respectively. For 60 cycle sample, Raman spectra show two prominent peaks at 554 cm{sup −1} and 1094 cm{sup −1}. The optical band gap values were found to be 3.76 eV, 3.72 eV and 3.67 eV for 20 cycle, 40 cycle and 60 cycle samples respectively.

Effect of surface bilayer charges on the magnetic field around ionic channels

Energy Technology Data Exchange (ETDEWEB)

Gomes Soares, Marília Amável [Post-graduation in Computational Sciences, Rio de Janeiro State University (Brazil); Cortez, Celia Martins, E-mail: ccortezs@ime.uerj.br [Post-graduation in Computational Sciences, Rio de Janeiro State University (Brazil); Department of Applied Mathematics, Rio de Janeiro State University (Brazil); Oliveira Cruz, Frederico Alan de [Post-graduation in Computational Sciences, Rio de Janeiro State University (Brazil); Department of Physics, Rural Federal University of Rio de Janeiro (Brazil); Silva, Dilson [Post-graduation in Computational Sciences, Rio de Janeiro State University (Brazil); Department of Applied Mathematics, Rio de Janeiro State University (Brazil)

2017-01-01

In this work, we present a physic-mathematical model for representing the ion transport through membrane channels, in special Na{sup +} and K{sup +}-channels, and discuss the influence of surface bilayer charges on the magnetic field behavior around the ionic current. The model was composed of a set of equations, including: a nonlinear differential Poisson-Boltzmann equation which usually allows to estimate the surface potentials and electric potential profile across membrane; equations for the ionic flux through channel and the ionic current density based on Armstrong's model for Na{sup +} and K{sup +} permeability and other Physics concepts; and a magnetic field expression derived from the classical Ampère equation. Results from computational simulations using the finite element method suggest that the ionic permeability is strongly dependent of surface bilayer charges, the current density through a K{sup +}-channel is very less sensible to temperature changes than the current density through a Na{sup +}- channel, active Na{sup +}-channels do not directly interfere with the K{sup +}-channels around, and vice-versa, since the magnetic perturbation generated by an active channel is of short-range.

Determination of sulfonamides in butter samples by ionic liquid magnetic bar liquid-phase microextraction high-performance liquid chromatography.

Science.gov (United States)

Wu, Lijie; Song, Ying; Hu, Mingzhu; Xu, Xu; Zhang, Hanqi; Yu, Aimin; Ma, Qiang; Wang, Ziming

2015-01-01

A novel, simple, and environmentally friendly pretreatment method, ionic liquid magnetic bar liquid-phase microextraction, was developed for the determination of sulfonamides in butter samples by high-performance liquid chromatography. The ionic liquid magnetic bar was prepared by inserting a stainless steel wire into the hollow of a hollow fiber and immobilizing ionic liquid in the micropores of the hollow fiber. In the extraction process, the ionic liquid magnetic bars were used to stir the mixture of sample and extraction solvent and enrich the sulfonamides in the mixture. After extraction, the analyte-adsorbed ionic liquid magnetic bars were readily isolated with a magnet from the extraction system. It is notable that the present method was environmentally friendly since water and only several microliters of ionic liquid were used in the whole extraction process. Several parameters affecting the extraction efficiency were investigated and optimized, including the type of ionic liquid, sample-to-extraction solvent ratio, the number of ionic liquid magnetic bars, extraction temperature, extraction time, salt concentration, stirring speed, pH of the extraction solvent, and desorption conditions. The recoveries were in the range of 73.25-103.85 % and the relative standard deviations were lower than 6.84 %. The experiment results indicated that the present method was effective for the extraction of sulfonamides in high-fat content samples.

Li(Zn,Co,MnAs: A bulk form diluted magnetic semiconductor with Co and Mn co-doping at Zn sites

Directory of Open Access Journals (Sweden)

Bijuan Chen

2016-11-01

Full Text Available We report the synthesis and characterization of a series of bulk forms of diluted magnetic semiconductors Li(Zn1-x-yCoxMnyAs with a crystal structure close to that of III-V diluted magnetic semiconductor (Ga,MnAs. No ferromagnetic order occurs with single (Zn,Co or (Zn, Mn substitution in the parent compound LiZnAs. Only with co-doped Co and Mn ferromagnetic ordering can occur at the Curie temperature ∼40 K. The maximum saturation moment of the this system reached to 2.17μB/Mn, which is comparable to that of Li (Zn,MnAs. It is the first time that a diluted magnetic semiconductor with co-doping Co and Mn into Zn sites is achieved in “111” LiZnAs system, which could be utilized to investigate the basic science of ferromagnetism in diluted magnetic semiconductors. In addition, ferromagnetic Li(Zn,Co,MnAs, antiferromagnetic LiMnAs, and superconducting LiFeAs share square lattice at As layers, which may enable the development of novel heterojunction devices in the future.

Magnetic properties and loss separation in FeSi/MnZnFe{sub 2}O{sub 4} soft magnetic composites

Energy Technology Data Exchange (ETDEWEB)

Lauda, M. [Institute of Physics, Faculty of Science, Pavol Jozef Šafárik Univesity, Park Angelinum 9, 04154 Košice (Slovakia); Füzer, J., E-mail: jan.fuzer@upjs.sk [Institute of Physics, Faculty of Science, Pavol Jozef Šafárik Univesity, Park Angelinum 9, 04154 Košice (Slovakia); Kollár, P. [Institute of Physics, Faculty of Science, Pavol Jozef Šafárik Univesity, Park Angelinum 9, 04154 Košice (Slovakia); Strečková, M.; Bureš, R. [Institute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 04001 Košice (Slovakia); Kováč, J.; Baťková, M.; Baťko, I. [Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 04001 Košice (Slovakia)

2016-08-01

We investigated composites that have been prepared from FeSi powders covered with MnZnFe{sub 2}O{sub 4} (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. - Highlights: • Successful preparation of soft magnetic composite FeSi/MnZnFe{sub 2}O{sub 4}. • Study of the complex magnetic permeability. • Comparison of different compositions of prepared SMC's. • Determination of parts of magnetic losses.

Effect of Ga doping and point defect on magnetism of ZnO

Energy Technology Data Exchange (ETDEWEB)

Hou, Qingyu [College of Science, Inner Mongolia University of Technology, 010051 Hohhot (China); Zhao, Chunwang, E-mail: cwzhao@shmtu.edu.cn [College of Arts and Sciences, Shanghai Maritime University, 201306 Shanghai (China); Jia, Xiaofang; Qu, Lingfeng [College of Science, Inner Mongolia University of Technology, 010051 Hohhot (China)

2017-02-01

The combined influence mechanism of Ga doping and Zn vacancy or O vacancy on magnetism of ZnO is studied using the first-principle calculation. The coexistence of Ga doping and Zn vacancy can achieve a Curie temperature higher than room temperature and the Ga doped ZnO system is a p-type diluted degenerate semiconductor with metalized ferromagnetism. The magnetism of the doping system of Ga doping and Zn vacancy is mainly contributed by double-exchange interaction through the holes of Zn vacancy taking carrier as medium. However, the system of Ga doping and O vacancy is non-magnetic. In the coexistence of Ga doping and Zn vacancy or O vacancy, a close relative distance between doping and vacancy will reduce the formation energy of the doping system but increase the easiness of doping and vacancy, as well as enhance the stability of the doping system.

Quantitative Determination on Ionic-Liquid-Gating Control of Interfacial Magnetism.

Science.gov (United States)

Zhao, Shishun; Zhou, Ziyao; Peng, Bin; Zhu, Mingmin; Feng, Mengmeng; Yang, Qu; Yan, Yuan; Ren, Wei; Ye, Zuo-Guang; Liu, Yaohua; Liu, Ming

2017-05-01

Ionic-liquid gating on a functional thin film with a low voltage has drawn a lot of attention due to rich chemical, electronic, and magnetic phenomena at the interface. Here, a key challenge in quantitative determination of voltage-controlled magnetic anisotropy (VCMA) in Au/[DEME] + [TFSI] - /Co field-effect transistor heterostructures is addressed. The magnetic anisotropy change as response to the gating voltage is precisely detected by in situ electron spin resonance measurements. A reversible change of magnetic anisotropy up to 219 Oe is achieved with a low gating voltage of 1.5 V at room temperature, corresponding to a record high VCMA coefficient of ≈146 Oe V -1 . Two gating effects, the electrostatic doping and electrochemical reaction, are distinguished at various gating voltage regions, as confirmed by X-ray photoelectron spectroscopy and atomic force microscopy experiments. This work shows a unique ionic-liquid-gating system for strong interfacial magnetoelectric coupling with many practical advantages, paving the way toward ion-liquid-gating spintronic/electronic devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electronic structure, magnetic and structural properties of Ni doped ZnO nanoparticles

International Nuclear Information System (INIS)

Kumar, Shalendra; Vats, Prashant; Gautam, S.; Gupta, V.P.; Verma, K.D.; Chae, K.H.; Hashim, Mohd; Choi, H.K.

2014-01-01

Highlights: • XRD, and HR-TEM results show the single phase nature of Ni doped ZnO nanoparticles. • dc magnetization results indicate the RT-FM in Ni doped ZnO nanoparticles. • Ni L 3,2 edge NEXAFS spectra infer that Ni ions are in +2 valence state. • O K edge NEXAFS spectra show that O vacancy increases with Ni doping in ZnO. - Abstract: We report structural, magnetic and electronic structural properties of Ni doped ZnO nanoparticles prepared by auto-combustion method. The prepared nanoparticles were characterized by using X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), near edge X-ray absorption fine structure (NEXAFS) spectroscopy, and dc magnetization measurements. The XRD and HR-TEM results indicate that Ni doped ZnO nanoparticles have single phase nature with wurtzite lattice and exclude the presence of secondary phase. NEXAFS measurements performed at Ni L 3,2 -edges indicates that Ni ions are in +2 valence state and exclude the presence of Ni metal clusters. O K-edge NEXAFS spectra indicate an increase in oxygen vacancies with Ni-doping, while Zn L 3,2 -edge show the absence of Zn-vacancies. The magnetization measurements performed at room temperature shows that pure and Ni doped ZnO exhibits ferromagnetic behavior

Atomic and ionic density measurement by laser absorption spectroscopy of magnetized or non-magnetized plasmas

International Nuclear Information System (INIS)

Le Gourrierec, P.

1989-11-01

Laser absorption spectroscopy is an appreciated diagnostic in plasma physics to measure atomic and ionic densities. We used it here more specifically on metallic plasmas. Firstly, a uranium plasma was created in a hollow cathode. 17 levels of U.I and U.II (12 for U.I and 5 for U.II) are measured by this method. The results are compared with the calculated levels of two models (collisional-radiative and LTE). Secondly, the theory of absorption in presence of a magnetic field is recalled and checked. Then, low-density magnetized plasma produced on our ERIC experiment (acronym for Experiment of Resonance Ionic Cyclotron), have been diagnosed successfully. The use of this technique on a low density plasma has not yet been published to our knowledge. The transverse temperature and the density of a metastable atomic level of a barium plasma has been derived. The evolution of a metastable ionic level of this element is studied in terms of two source parameters (furnace temperature and injected hyperfrequency power) [fr

Defect characterization and magnetic properties in un-doped ZnO thin film annealed in a strong magnetic field

International Nuclear Information System (INIS)

Ning Shuai; Zhan Peng; Wang Wei-Peng; Li Zheng-Cao; Zhang Zheng-Jun

2014-01-01

Highly c-axis oriented un-doped zinc oxide (ZnO) thin films, each with a thickness of ∼ 100 nm, are deposited on Si (001) substrates by pulsed electron beam deposition at a temperature of ∼ 320 °C, followed by annealing at 650 °C in argon in a strong magnetic field. X-ray photoelectron spectroscopy (XPS), positron annihilation analysis (PAS), and electron paramagnetic resonance (EPR) characterizations suggest that the major defects generated in these ZnO films are oxygen vacancies. Photoluminescence (PL) and magnetic property measurements indicate that the room-temperature ferromagnetism in the un-doped ZnO film originates from the singly ionized oxygen vacancies whose number depends on the strength of the magnetic field applied in the thermal annealing process. The effects of the magnetic field on the defect generation in the ZnO films are also discussed. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

First-principles study on stability and magnetism of AlnZn (n=1-9) clusters

International Nuclear Information System (INIS)

Ren Xiaojun; Li Baoxing

2010-01-01

We have investigated the structures, stabilities and magnetism of zinc-doped Al n (n=1-9) clusters in detail by using first-principles density functional theory. Our calculated results indicate that the ground state structures of the mixed Al n Zn (n=1-9) clusters doped with one zinc atom can be obtained from the most stable structures of the pure Al n (n=2-10) clusters by substitutional type. The impurity atom causes local structural distortion due to different atomic radii and different bonding characteristics. It is found that the clusters with total atom numbers of 3 and 7 exhibit high stability. In addition, the energy gaps E g s between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) show obvious even/odd alternation with cluster size. Furthermore, we investigate the magnetism of the mixed clusters. The Al 4 Zn, Al 6 Zn and Al 8 Zn clusters with even number of electrons do not have any magnetism. All Al 1 Zn, Al 5 Zn, Al 7 Zn and Al 9 Zn clusters have the total magnetic moment of 1.0 μ B due to one unpaired electron. Unexpectedly, the Al 2 Zn and Al 3 Zn clusters show total magnetic moments of 2.0 and 3.0 μ B , respectively. The magnetism arises from the sp-d hybridization due to charge transfer and the influence of the impurity zinc atom.

Hydrophobic ZnO nanostructured thin films on glass substrate by simple successive ionic layer absorption and reaction (SILAR) method

Energy Technology Data Exchange (ETDEWEB)

Kumar, P. Suresh; Raj, A. Dhayal [Thin Film and Nanomaterials Laboratory, Department of Physics, Bharathiar University, Coimbatore-641046 (India); Mangalaraj, D., E-mail: dmraj800@yahoo.co [Department of Nanoscience and Technology, Bharathiar University, Coimbatore-641046 (India); Nataraj, D. [Thin Film and Nanomaterials Laboratory, Department of Physics, Bharathiar University, Coimbatore-641046 (India)

2010-10-01

In the present work, ZnO nanostructured thin films were grown on glass substrates by a simple successive ionic layer absorption and reaction method (SILAR) process at relatively low temperature for its self cleaning application. X-ray diffraction, scanning electron microscopy and Photoluminescence (PL) spectra were used to characterize the prepared ZnO nanostructured film. XRD pattern clearly reviles that the grown ZnO nanostructure film reflect (002) orientation with c-direction. SEM image clearly shows the surface morphology with cluster of spindle and flower-like nanostructured with diameter various around 350 nm. Photoluminescence (PL) spectra of ZnO nanostructures film exhibit a UV emission around 385nm and visible emission in the range around 420-500 nm. Good water repellent behavior were observed for ZnO nanostructured film without any surface modification.

Hydrophobic ZnO nanostructured thin films on glass substrate by simple successive ionic layer absorption and reaction (SILAR) method

International Nuclear Information System (INIS)

Kumar, P. Suresh; Raj, A. Dhayal; Mangalaraj, D.; Nataraj, D.

2010-01-01

In the present work, ZnO nanostructured thin films were grown on glass substrates by a simple successive ionic layer absorption and reaction method (SILAR) process at relatively low temperature for its self cleaning application. X-ray diffraction, scanning electron microscopy and Photoluminescence (PL) spectra were used to characterize the prepared ZnO nanostructured film. XRD pattern clearly reviles that the grown ZnO nanostructure film reflect (002) orientation with c-direction. SEM image clearly shows the surface morphology with cluster of spindle and flower-like nanostructured with diameter various around 350 nm. Photoluminescence (PL) spectra of ZnO nanostructures film exhibit a UV emission around 385nm and visible emission in the range around 420-500 nm. Good water repellent behavior were observed for ZnO nanostructured film without any surface modification.

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

International Nuclear Information System (INIS)

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

2011-01-01

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

Magnetic Modulation of the Transport of Organophilic Solutes through Supported Magnetic Ionic Liquid Membranes.

Czech Academy of Sciences Publication Activity Database

Daniel, C.L.; Rubio, A.M.; Sebastião, P.J.; Afonso, C.A.M.; Storch, Jan; Izák, Pavel; Portugal, C.A.M.; Crespo, J.G.

2016-01-01

Roč. 505, MAY 1 (2016), s. 36-43 ISSN 0376-7388 R&D Projects: GA ČR(CZ) GAP106/12/0569 Grant - others:ERANET(PT) ERA-CHEM/0001/2008; EUI(ES) 2008- 03857; FCT-MCTES(PT) SFRH/BD/81552/2011 Institutional support: RVO:67985858 Keywords : magnetic ionic liquids (MILs) * solute transport modulation * magnetic field Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 6.035, year: 2016

Ab initio investigation on the magnetic ordering in Gd doped ZnO

KAUST Repository

Bantounas, Ioannis; Goumri-Said, Souraya; Benali Kanoun, Mohammed; Manchon, Aurelien; Roqan, Iman S.; Schwingenschlö gl, Udo

2011-01-01

The current study investigates the magnetic properties of the Gdx Zn1−xO, with x=0.0625 and 0.0185, dopedsemiconductor using the full potential (linearized) augmented plane wave plus local orbital method. We show that in contrast to the findings of Shi et al. [J. Appl. Phys. 106, 023910 (2009)], the implementation of the Hubbard U parameter to the Gd f states favors an antiferromagnetic phase in both wurtzite GdO and Gdx Zn1−xO. Spin polarized calculations on Gdx Zn1−xO indicate that, even if a ferromagnetic ground state were favored, the magnetic influence of Gd in a perfect ZnO wurtzite lattice is highly localized and limited to the first three nearest neighboring O atoms. Increasing the supercell size and thus diluting the concentration of Gd within the ZnO matrix does not show any changes in the net magnetic moment between these three O atoms nor in the remaining lattice sites, indicating that sizing effects do not influence the range of matrix polarization. We conclude that the localized Gd induced polarization can not account for long range magnetic ordering in a defect-free ZnO wurtzite lattice.

Ab initio investigation on the magnetic ordering in Gd doped ZnO

KAUST Repository

Bantounas, Ioannis

2011-04-22

The current study investigates the magnetic properties of the Gdx Zn1−xO, with x=0.0625 and 0.0185, dopedsemiconductor using the full potential (linearized) augmented plane wave plus local orbital method. We show that in contrast to the findings of Shi et al. [J. Appl. Phys. 106, 023910 (2009)], the implementation of the Hubbard U parameter to the Gd f states favors an antiferromagnetic phase in both wurtzite GdO and Gdx Zn1−xO. Spin polarized calculations on Gdx Zn1−xO indicate that, even if a ferromagnetic ground state were favored, the magnetic influence of Gd in a perfect ZnO wurtzite lattice is highly localized and limited to the first three nearest neighboring O atoms. Increasing the supercell size and thus diluting the concentration of Gd within the ZnO matrix does not show any changes in the net magnetic moment between these three O atoms nor in the remaining lattice sites, indicating that sizing effects do not influence the range of matrix polarization. We conclude that the localized Gd induced polarization can not account for long range magnetic ordering in a defect-free ZnO wurtzite lattice.

Defect characterization and magnetic properties in un-doped ZnO thin film annealed in a strong magnetic field

Science.gov (United States)

Ning, Shuai; Zhan, Peng; Wang, Wei-Peng; Li, Zheng-Cao; Zhang, Zheng-Jun

2014-12-01

Highly c-axis oriented un-doped zinc oxide (ZnO) thin films, each with a thickness of ~ 100 nm, are deposited on Si (001) substrates by pulsed electron beam deposition at a temperature of ~ 320 °C, followed by annealing at 650 °C in argon in a strong magnetic field. X-ray photoelectron spectroscopy (XPS), positron annihilation analysis (PAS), and electron paramagnetic resonance (EPR) characterizations suggest that the major defects generated in these ZnO films are oxygen vacancies. Photoluminescence (PL) and magnetic property measurements indicate that the room-temperature ferromagnetism in the un-doped ZnO film originates from the singly ionized oxygen vacancies whose number depends on the strength of the magnetic field applied in the thermal annealing process. The effects of the magnetic field on the defect generation in the ZnO films are also discussed.

The impact of processing parameters on the properties of Zn-bonded Nd–Fe–B magnets

Energy Technology Data Exchange (ETDEWEB)

Kelhar, Luka, E-mail: luka.kelhar@ijs.si [Department for Nanostructured Materials, Jožef Stefan Institute, Jamova cesta 39, Ljubljana 1000 (Slovenia); Zavašnik, Janez [Centre for Electron Microscopy and Microanalysis (CEMM), Jamova cesta 39, Ljubljana 1000 (Slovenia); McGuiness, Paul; Kobe, Spomenka [Department for Nanostructured Materials, Jožef Stefan Institute, Jamova cesta 39, Ljubljana 1000 (Slovenia); Jožef Stefan International Postgraduate School, Jamova cesta 39, Ljubljana 1000 (Slovenia)

2016-12-01

We report on the effect of loading factor and pressure on the density and the magnetic properties of Zn-bonded Nd–Fe–B magnets produced by pulsed-electric-current sintering (PECS). The idea behind this study is to fabricate bonded magnets with a metallic binder in order for the bonded magnet to operate at temperatures higher than 180 °C: the current upper-limit for polymer-bonded magnets. These composites are made of hard-magnetic powder in the form of melt-spun ribbons bonded with the low-melting-point metal Zn. The binder additions were varied from 10 to 30 wt%, and pressures of 50 and 500 MPa were applied. The high-pressure mode with 20 wt% Zn resulted in a 24% increase of J{sub r}, compared to the low-pressure mode. The magnetic measurements revealed a maximum remanence of 0.64 T for 10 wt% Zn, while the coercivity is largely unaffected by the processing conditions. The density of the composites was up to 7.0 g/cm{sup 3}, corresponding to 94% of the theoretical density. Compared to commercial polymer-bonded magnets, the Zn-bonded counterparts exhibit a slightly lower J{sub r}, but the coercivity is retained. We show that there is a minor diffusion of Zn into the Nd–Fe–B, forming a 1 μm thin transition layer, but it does not harm the magnetic properties. These metal-bonded Nd–Fe–B magnets are ideal for use in high-temperature automotive applications like under-the-hood sensors and other magnet-based devices that are close to the engine. - Highlights: • Fabrication of Zn-bonded Nd–Fe–B magnets by pulsed electric current sintering. • Interesting for automotive applications with temperature exceeding 180 °C. • Variations of pressure and loading factor result in higher density and remanence. • Minor diffusion of Zn binder into the MQP-B ribbons is revealed, but does not decrease the magnetic properties. • More stable magnetic properties at high-temperature due to metallic Zn-binder.

Structural, magnetic and electronic structure properties of Co doped ZnO nanoparticles

International Nuclear Information System (INIS)

Kumar, Shalendra; Song, T.K.; Gautam, Sanjeev; Chae, K.H.; Kim, S.S.; Jang, K.W.

2015-01-01

Highlights: • XRD and HR-TEM results show the single phase nature of Co doped ZnO nanoparticles. • XMCD and dc magnetization results indicate the RT-FM in Co doped ZnO nanoparticles. • Co L 3,2 NEXAFS spectra infer that Co ions are in 2+ valence state. • O K edge NEXAFS spectra show that O vacancy increases with Co doping in ZnO. - Abstract: We reported structural, magnetic and electronic structure studies of Co doped ZnO nanoparticles. Doping of Co ions in ZnO host matrix has been studied and confirmed using various methods; such as X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersed X-ray (EDX), high resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), near edge X-ray absorption fine structure (NEXAFS) spectroscopy, magnetic hysteresis loop measurements and X-ray magnetic circular dichroism (XMCD). From the XRD and HR-TEM results, it is observed that Co doped ZnO nanoparticles have single phase nature with wurtzite structure and exclude the possibility of secondary phase formation. FE-SEM and TEM micrographs show that pure and Co doped nanoparticles are nearly spherical in shape. O K edge NEXAFS spectra indicate that O vacancies increase with Co doping. The Co L 3,2 edge NEXAFS spectra revealed that Co ions are in 2+ valence state. DC magnetization hysteresis loops and XMCD results clearly showed the intrinsic origin of temperature ferromagnetism in Co doped ZnO nanoparticles

Room temperature deposition of ZnSe thin films by successive ionic layer adsorption and reaction (SILAR) method

International Nuclear Information System (INIS)

Kale, R.B.; Lokhande, C.D.

2004-01-01

The zinc selenide (ZnSe) thin films are deposited onto glass substrate using relatively simple and inexpensive successive ionic layer adsorption and reaction (SILAR) method. The films are deposited using zinc acetate sodium selenosulphate precursors. The concentration, pH, immersion and rinsing times and number of immersion cycles have been optimized to obtain good quality ZnSe thin films. The X-ray diffraction (XRD) study and scanning electron microscopy (SEM) studies reveals nanocrystalline nature alongwith some amorphous phase present in ZnSe thin films. Energy dispersive X-ray (EDAX) analysis shows that the films are Se deficient. From optical absorption data, the optical band gap 'E g ' for as-deposited thin film was found to be 2.8 eV and electrical resistivity in the order of 10 7 Ω cm

Influence of the magnetic dead layer thickness of Mg-Zn ferrites nanoparticle on their magnetic properties

Energy Technology Data Exchange (ETDEWEB)

El-Sayed, H.M. [Physics Department, Faculty of Science, Ain Shams University, Cairo (Egypt); Ali, I.A.; Azzam, A. [Nuclear Physics Department, Nuclear Research Center, Atomic Energy Authority (Egypt); Sattar, A.A. [Physics Department, Faculty of Science, Ain Shams University, Cairo (Egypt)

2017-02-15

Nanoparticle ferrite with chemical formula Mg{sub (1−x)}Zn{sub x}Fe{sub 2}O{sub 4} (where x=0.0, 0.2, 0.4, 0.6, 0.8 and 1) were prepared by sol-gel technique. Single phase structure of these ferrites was confirmed using X-ray diffraction (XRD). Transmission Electron Microscope (TEM) showed that the particle size of the samples in the range of (5.7–10.6 nm). The hysteresis studies showed superparamagnetic behaviour at room temperature. The magnetization behaviour with Zn-content is expressed in the light of Yafet-Kittel angles. The dead layer thickness (t) was calculated and its effect on the magnetization and magnetic losses was debated. The Specific Absorption Rate (SAR) in an alternating magnetic field with frequency 198 kHz for these ferrites has been studied. It is found that, the thickness of magnetic dead layer of the surface of the materials has greatly affected the SAR value of the samples. - Highlights: • Synthesis of Mg-Zn nanoparticle ferrite by sol-gel technique. • Methods of dead layer thickness calculation. • Magnetic behaviour explanation. • Relation between the Specific Absorption Rate, dead layer thickness and particle size.

Diffusion of Magnetized Binary Ionic Mixtures at Ultracold Plasma Conditions

Science.gov (United States)

Vidal, Keith R.; Baalrud, Scott D.

2017-10-01

Ultracold plasma experiments offer an accessible means to test transport theories for strongly coupled systems. Application of an external magnetic field might further increase their utility by inhibiting heating mechanisms of ions and electrons and increasing the temperature at which strong coupling effects are observed. We present results focused on developing and validating a transport theory to describe binary ionic mixtures across a wide range of coupling and magnetization strengths relevant to ultracold plasma experiments. The transport theory is an extension of the Effective Potential Theory (EPT), which has been shown to accurately model correlation effects at these conditions, to include magnetization. We focus on diffusion as it can be measured in ultracold plasma experiments. Using EPT within the framework of the Chapman-Enskog expansion, the parallel and perpendicular self and interdiffusion coefficients for binary ionic mixtures with varying mass ratios are calculated and are compared to molecular dynamics simulations. The theory is found to accurately extend Braginskii-like transport to stronger coupling, but to break down when the magnetization strength becomes large enough that the typical gyroradius is smaller than the interaction scale length. This material is based upon work supported by the Air Force Office of Scientific Research under Award Number FA9550-16-1-0221.

Magnetism and magnetoresistance from different origins in Co/ZnO:Al granular films

Energy Technology Data Exchange (ETDEWEB)

Quan, Zhiyong, E-mail: quanzy@sxnu.edu.cn; Liu, Xia; Song, Zhilin; Xu, Xiaohong, E-mail: xuxh@dns.sxnu.edu.cn

2016-12-01

Co/ZnO:Al granular films were made on glass substrates by sequential magnetron sputter deposition of ultrathin Co layer and ZnO:Al layer at room temperature. The as-deposited films consist of superparamagnetic Co particles dispersed in ZnO:Al (~2% Al) semiconductor matrix. Distinguished magnetoresistance effect at room temperature was obtained in the as-deposited films, which obviously reduced after annealing due to the growth of Co particles. The size of important magnetic particles was analyzed by Langevin function for hysteresis loops and magnetoresistance curves at room temperature. It was found that small magnetic particle contribute to magnetoresistance behavior and large particles dominate the room temperature magnetism in Co/ZnO:Al granular films.

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

International Nuclear Information System (INIS)

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

2016-01-01

The structural, magnetic and magneto-transport of undoped ZnO, Zn_0_._9_7Al_0_._0_3O, Zn_0_._9_5Fe_0_._0_5O and Zn_0_._9_2Al_0_._0_3Fe_0_._0_5O 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. - Highlights: • Al, Fe, Al–Fe co-doped and undoped films of ZnO are deposited on Si by PLD. • Single phase (002) oriented Wurtzite ZnO phase is formed for all films. • Fe doped and Fe–Al co-doped ZnO films reveal magnetic hysteresis at 300 K. • Negative magnetoresistance is observed in undoped and Fe–Al co-doped ZnO film. • It is apparent that charge carriers are coupled with the local magnetic moment.

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

Energy Technology Data Exchange (ETDEWEB)

Kumar, Santosh, E-mail: skphysics@yahoo.co.in [Department of Physics, College of Commerce, Arts & Science, Patna 800020, Bihar (India); Deepika [Department of Physics, College of Commerce, Arts & Science, Patna 800020, Bihar (India); Tripathi, Malvika [UGC DAE, Consortium for scientific research, Indore 452001, Madhya Pradesh (India); Vaibhav, Pratyush [Jaypee University of Engineering and Technology, Guna 473226, Madhya Pradesh (India); Kumar, Aman [Indian Institute of Technology, Roorkee (India); Kumar, Ritesh [Department of Physics, College of Commerce, Arts & Science, Patna 800020, Bihar (India); Choudhary, R.J., E-mail: ram@csr.res.in [UGC DAE, Consortium for scientific research, Indore 452001, Madhya Pradesh (India); Phase, D.M. [UGC DAE, Consortium for scientific research, Indore 452001, Madhya Pradesh (India)

2016-12-01

The structural, magnetic and magneto-transport of undoped ZnO, Zn{sub 0.97}Al{sub 0.03}O, Zn{sub 0.95}Fe{sub 0.05}O and Zn{sub 0.92}Al{sub 0.03}Fe{sub 0.05}O 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. - Highlights: • Al, Fe, Al–Fe co-doped and undoped films of ZnO are deposited on Si by PLD. • Single phase (002) oriented Wurtzite ZnO phase is formed for all films. • Fe doped and Fe–Al co-doped ZnO films reveal magnetic hysteresis at 300 K. • Negative magnetoresistance is observed in undoped and Fe–Al co-doped ZnO film. • It is apparent that charge carriers are coupled with the local magnetic moment.

In-situ functionalization of mesoporous hexagonal ZnO synthesized in task specific ionic liquid as a photocatalyst for elimination of SO2, NOx, and CO

Science.gov (United States)

Kowsari, Elaheh; Abdpour, Soheil

2017-12-01

A novel mesoporous structure of zinc oxide was synthesized in hydrothermal autocalve in the presence of a functional ionic liquid (FIL) {[CH2CH2] O2 (mm)2}. This FIL with ether groups was used simultaneously as a designer templating agent and a source of the hydroxyl radical. The presence of this ionic liquid led to producing ethylene glycol in the reaction media, which adsorb on the surface of mesoporous hexagonal ZnO plates. These mesoporous structures can adsorb pollutant gases and increase photocatalytic oxidation of pollutant gases in compare with commercial ZnO nanoparticles and agglomerated nanoparticles synthesized in this work. XPS data confirmed ethylene glycol production by the ionic liquid, which could prove a role for ionic liquids as designers. The estimated BET surface area values of ZnO hexagonal mesoporous plates and agglomerated particles were 84 m2/g and 12 m2/g respectively. Optical properties of the mesoporous structures were analyzed by photoluminescence spectroscopy and diffuse reflectance UV-visible spectroscopy. The performance of these structures as efficient photocatalysts was further demonstrated by their removal of NOx, SO2, and CO under UV irradiation. The removal of NOx, SO2, and CO under UV irradiation was 56%, 81%, and 35% respectively, after 40 min of irradiation time. Reusability of the photocatalyst was determined; the results show no significant decrease of activity of photocatalyst. after five cycles.

Effects of acute exposure to magnetic field on ionic composition of frog sciatic nerve

International Nuclear Information System (INIS)

Salem, A.; Hafedh, A.; Mohsen, S.

2004-01-01

Objective: To evaluate the possible interaction between magnetic field and cadmium on ionic composition of frog sciatic nerve. Design: The combined effect of magnetic field and cadmium (1.5mg/kg; in lymphatic sac) were studied in frog sciatic nerves (Rana Esculenta). Sciatic nerve samples were extracted, weighed and mixed in bidistilled water in order to analyze by inductively coupled plasma (ICP) ionic composition. Setting: Frogs (Rana Esculenta) were reared in swimming-pool (Faculte des Sciences de Bizerte, Tunisia). Frogs were cared for under the Tunisian Code of Practice for the Care and Use of Animals for Scientific purpose and the Experimental Protocols were approved by the Ethics Committee. Subjects: Treated and control groups (n=6) weighing 50-100g at the time of experiments were housed in the same condition three weeks before the beginning of the experiments. Results: Acute exposure to magnetic field increased significantly the calcium (+298%, p<0.05) and iron (+50%, p<0.05) contents of frog sciatic nerve, whereas magnesium and copper contents remained unchanged. The association between magnetic field and cadmium, induced marked increase of calcium (+360%, p<0.05), whereas magnesium content remained stable. Conclusions: Magnetic field exposure alters the ionic composition in the frog sciatic nerve, especially calcium and iron. Magnetic field magnifies the effect of cadmium on calcium homeostasis. (author)

Detection of Defect-Induced Magnetism in Low-Dimensional ZnO Structures by Magnetophotocurrent.

Science.gov (United States)

Lorite, Israel; Kumar, Yogesh; Esquinazi, Pablo; Zandalazini, Carlos; de Heluani, Silvia Perez

2015-09-09

The detection of defect-induced magnetic order in single low-dimensional oxide structures is in general difficult because of the relatively small yield of magnetically ordered regions. In this work, the effect of an external magnetic field on the transient photocurrent measured after light irradiation on different ZnO samples at room temperature is studied. It has been found that a magnetic field produces a change in the relaxation rate of the transient photocurrent only in magnetically ordered ZnO samples. This rate can decrease or increase with field, depending on whether the magnetically ordered region is in the bulk or only at the surface of the ZnO sample. The phenomenon reported here is of importance for the development of magneto-optical low-dimensional oxides devices and provides a new guideline for the detection of magnetic order in low-dimensional magnetic semiconductors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Magnetic properties in (Mn,Fe)-codoped ZnO nanowire

International Nuclear Information System (INIS)

Cao, Huawei; Lu, Pengfei; Cong, Zixiang; Yu, Zhongyuan; Cai, Ningning; Zhang, Xianlong; Gao, Tao; Wang, Shumin

2013-01-01

Using the first-principles density functional theory, we have studied the electronic structures and magnetic properties of Mn/Fe codoped ZnO nanowires systematically. The calculated results of formation energy indicate that the configuration of the lowest energy where Mn and Fe atoms form nearest neighbors on the outer cylindrical surface layer along the [0001] direction, will be determined. The magnetic coupling of 8 types of Mn/Fe codoped ZnO nanowires was investigated and ferromagnetic state was found in certain configurations. The mechanism is from the fierce hybridization between 3d of Mn and Fe with O 2p near the Fermi level. The relative energy difference for configuration VIII is 0.221 eV, which indicates that room temperature ferromagnetism could be obtained in such a system and Mn/Fe codoped ZnO nanowires are a promising nanoscale spintronic material. - Highlights: • The stable structure prefers that Mn/Fe form nearest neighbors on the outer surface. • The fierce p–d hybridization is responsible for ferromagnetic (FM) coupling. • Mn/Fe codoped ZnO nanowire is a promising FM semiconductor material

Magnetic properties in (Mn,Fe)-codoped ZnO nanowire

Energy Technology Data Exchange (ETDEWEB)

Cao, Huawei [Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education, Beijing 100876 (China); Lu, Pengfei, E-mail: photon.bupt@gmail.com [Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education, Beijing 100876 (China); Cong, Zixiang [School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100976 (China); Yu, Zhongyuan; Cai, Ningning; Zhang, Xianlong [Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education, Beijing 100876 (China); Gao, Tao [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Wang, Shumin [Photonics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Gothenburg (Sweden); State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China)

2013-12-02

Using the first-principles density functional theory, we have studied the electronic structures and magnetic properties of Mn/Fe codoped ZnO nanowires systematically. The calculated results of formation energy indicate that the configuration of the lowest energy where Mn and Fe atoms form nearest neighbors on the outer cylindrical surface layer along the [0001] direction, will be determined. The magnetic coupling of 8 types of Mn/Fe codoped ZnO nanowires was investigated and ferromagnetic state was found in certain configurations. The mechanism is from the fierce hybridization between 3d of Mn and Fe with O 2p near the Fermi level. The relative energy difference for configuration VIII is 0.221 eV, which indicates that room temperature ferromagnetism could be obtained in such a system and Mn/Fe codoped ZnO nanowires are a promising nanoscale spintronic material. - Highlights: • The stable structure prefers that Mn/Fe form nearest neighbors on the outer surface. • The fierce p–d hybridization is responsible for ferromagnetic (FM) coupling. • Mn/Fe codoped ZnO nanowire is a promising FM semiconductor material.

Lewis acidity dependency of the electrochemical window of zinc chloride-1-ethyl-3-methylimidazolium chloride ionic liquids

International Nuclear Information System (INIS)

Hsiu, S-I; Huang, J.-F.; Sun, I-W.; Yuan, C.-H.; Shiea, Jantaie

2002-01-01

Negative ion fast atom bombardment mass spectra (FAB-MS) recorded for ZnCl 2 -1-ethyl-3-methylimidazolium chloride (ZnCl 2 -EMIC) ionic liquids with various compositions indicate that various Lewis acidic chlorozincate clusters (ZnCl 3 - , Zn 2 Cl 5 - and Zn 3 Cl 7 - ) are present in ZnCl 2 -EMIC ionic liquids depending on the percentage of ZnCl 2 used in preparing the ionic liquids; higher ZnCl 2 percentage favors the larger clusters. Cyclic voltammetry reveals that the potential limits for a basic 1:3 ZnCl 2 -EMIC melt correspond to the cathodic reduction of EMI + and anodic oxidation of Cl - , giving an electrochemical window of approximately 3.0 V which is the same as that observed for basic AlCl 3 -EMIC ionic liquids. For acidic ionic liquids that have a ZnCl 2 /EMIC molar ratio higher than 0.5:1, the negative potential limit is due to the deposition of metallic zinc, and the positive potential limit is due to the oxidation of the chlorozincate complexes. All the acidic ionic liquids exhibit an electrochemical window of approximately 2 V, although the potential limits shifted in the positive direction with increasing ZnCl 2 mole ratio. Underpotential deposition of zinc was observed on Pt and Ni electrodes in the acidic ionic liquids. At proper temperatures and potentials, crystalline zinc electrodeposits were obtained from the acidic ionic liquids

The impact of processing parameters on the properties of Zn-bonded Nd-Fe-B magnets

Science.gov (United States)

Kelhar, Luka; Zavašnik, Janez; McGuiness, Paul; Kobe, Spomenka

2016-12-01

We report on the effect of loading factor and pressure on the density and the magnetic properties of Zn-bonded Nd-Fe-B magnets produced by pulsed-electric-current sintering (PECS). The idea behind this study is to fabricate bonded magnets with a metallic binder in order for the bonded magnet to operate at temperatures higher than 180 °C: the current upper-limit for polymer-bonded magnets. These composites are made of hard-magnetic powder in the form of melt-spun ribbons bonded with the low-melting-point metal Zn. The binder additions were varied from 10 to 30 wt%, and pressures of 50 and 500 MPa were applied. The high-pressure mode with 20 wt% Zn resulted in a 24% increase of Jr, compared to the low-pressure mode. The magnetic measurements revealed a maximum remanence of 0.64 T for 10 wt% Zn, while the coercivity is largely unaffected by the processing conditions. The density of the composites was up to 7.0 g/cm3, corresponding to 94% of the theoretical density. Compared to commercial polymer-bonded magnets, the Zn-bonded counterparts exhibit a slightly lower Jr, but the coercivity is retained. We show that there is a minor diffusion of Zn into the Nd-Fe-B, forming a 1 μm thin transition layer, but it does not harm the magnetic properties. These metal-bonded Nd-Fe-B magnets are ideal for use in high-temperature automotive applications like under-the-hood sensors and other magnet-based devices that are close to the engine.

Structure and magnetic properties of granular NiZn-ferrite - SiO2

Directory of Open Access Journals (Sweden)

Albuquerque Adriana Silva de

1999-01-01

Full Text Available Granular systems composed by nanostructured magnetic materials embedded in a non-magnetic matrix present unique physical properties that depend crucially on their nanostructure. In this work, we have studied the structural and magnetic properties of NiZn-ferrite nanoparticles embedded in SiO2, a granular system synthesized by sol-gel processing. Samples with ferrite volumetric fraction x ranging from 6% to 78% were prepared, and characterized by X-ray diffraction, Mössbauer spectroscopy and vibrating sample magnetometry. Our results show the formation of pure stoichiometric NiZn-ferrite in the SiO2 matrix for x < 34%. Above these fraction, our samples presented also small amounts of Fe2O3. Mössbauer spectroscopy revealed the superparamagnetic behaviour of the ferrimagnetic NiZn-ferrite nanoparticles. The combination of different ferrite concentration and heat treatments allowed the obtaintion of samples with saturation magnetization between 1.3 and 68 emu/g and coercivity ranging from 0 to 123 Oe, value which is two orders of magnitude higher than the coercivity of bulk NiZn-ferrite.

Ab initio understanding of magnetic properties in Zn2+ substitution of Fe3O4 ultra-thin film with dilute Zn substitution

Science.gov (United States)

Huang, Zhaocong; Chen, Qian; Jiang, Sheng; Dong, Shuai; Zhai, Ya

2018-05-01

The mechanism of the magnetic properties on the Zn2+ substituted Fe3O4 film have been investigated based on first principle calculations. It is found that the surface effect plays an important role in the occupation of Zn ion, and in turn changes the magnetic moment. It may also destroy the half metallic behavior of Fe3O4 film even if the Zn2+ concentration only is one Zn2+ per unit cell (4%), which is different from that in bulk material.

Probing magnetism and electronic structure of Fe-doped ZnO thin films

International Nuclear Information System (INIS)

El Amiri, A.; Moubah, R.; Lmai, F.; Abid, M.; Hassanain, N.; Hlil, E.K.; Lassri, H.

2016-01-01

Ab-initio calculations using Korringa–Kohn–Rostoker method combined with the coherent potential approximation were performed in order to study the magnetic properties of Fe-doped ZnO thin films with different Fe contents. The extracted parameters are compared with those determined experimentally. Based on total and partial densities of state curves, we demonstrate that there is a competition between p–d exchange and superexchange mechanisms leading to weak ferromagnetic and antiferromagnetic contributions, respectively. The dominant mechanism is found to be antiferromagnetic. However, with increasing Fe content the ferromagnetic contribution increases. In addition, the effect of structural defects on the magnetism of the system is reported. It is shown that both Zn and O vacancies increase ferromagnetism, which is more pronounced in case of Zn. - Highlights: • The KKR–CPA approach was used to study the magnetism of Fe-doped ZnO thin films. • There is a competition between p–d exchange and superexchange mechanisms leading to weak ferromagnetic and antiferromagnetic contributions. • Zn vacancies are more significant than the O ones for obtaining ferromagnetism.

Probing magnetism and electronic structure of Fe-doped ZnO thin films

Energy Technology Data Exchange (ETDEWEB)

El Amiri, A., E-mail: aelamiri@casablanca.ma [LPFA, Faculté des Sciences Ain Chock, Université Hassan II, BP 5366 Mâarif, Casablanca (Morocco); Moubah, R., E-mail: reda.moubah@hotmail.fr [LPMMAT, Faculté des Sciences Ain Chock, Université Hassan II, BP 5366 Mâarif, Casablanca (Morocco); Lmai, F. [LPTA, Faculté des Sciences Ain Chock, Université Hassan II, BP 5366 Mâarif, Casablanca (Morocco); Abid, M. [LPFA, Faculté des Sciences Ain Chock, Université Hassan II, BP 5366 Mâarif, Casablanca (Morocco); Hassanain, N. [Laboratoire de Physique des Matériaux, Faculté des Sciences, BP 1014 Rabat (Morocco); Hlil, E.K. [Institut Néel, CNRS et Université Joseph Fourier, BP 166, 38042 Grenoble (France); Lassri, H. [LPMMAT, Faculté des Sciences Ain Chock, Université Hassan II, BP 5366 Mâarif, Casablanca (Morocco)

2016-01-15

Ab-initio calculations using Korringa–Kohn–Rostoker method combined with the coherent potential approximation were performed in order to study the magnetic properties of Fe-doped ZnO thin films with different Fe contents. The extracted parameters are compared with those determined experimentally. Based on total and partial densities of state curves, we demonstrate that there is a competition between p–d exchange and superexchange mechanisms leading to weak ferromagnetic and antiferromagnetic contributions, respectively. The dominant mechanism is found to be antiferromagnetic. However, with increasing Fe content the ferromagnetic contribution increases. In addition, the effect of structural defects on the magnetism of the system is reported. It is shown that both Zn and O vacancies increase ferromagnetism, which is more pronounced in case of Zn. - Highlights: • The KKR–CPA approach was used to study the magnetism of Fe-doped ZnO thin films. • There is a competition between p–d exchange and superexchange mechanisms leading to weak ferromagnetic and antiferromagnetic contributions. • Zn vacancies are more significant than the O ones for obtaining ferromagnetism.

Cobalt-doped ZnO as dilute magnetic semiconductor; Cobalt dotiertes ZnO als verduennter magnetischer Halbleiter

Energy Technology Data Exchange (ETDEWEB)

Gacic, Milan

2009-04-24

Dilute magnetic semiconductors (DMS) are technologically promising materials that show ferromagnetic as well as semiconducting properties. These are one of the crucial compounds concerning the development of spintronic devices. The main problem so far ist that for applications the Curie temperature of most of the DMS compounds is much too low. However, DMS compounds based on ZnO as Zn{sub 1-x}Co{sub x}O seem to show ferromagnetism above room temperature, but the ferromagnetic exchange is not fully understood. Intensive experimental investigations need to be done. In the course of this theses Zn{sub 0.95}Co{sub 0.05}O thin films were fabricated by pulsed laser deposition and investigated concerning their magnetic, magnetoelectric and structural properties in order to understand the ferromagnetism in this material. Different experimental methods have been used, as magnetometry, X-ray diffraction (XRD), X-ray magnetic circular dichroism (XMCD), electron spin resonance (ESR) and magnetoelectric transport measurements. At special preparation conditions, where a high defect density is induced, the samples are clearly ferromagnetic above room temperature with a saturation magnetization of 2 {mu}{sub b}/Co and a remanence of 90%. Electrical transport measurements show a clear magnetoresistance as well as a anomalous Hall effect. The anomalous Hall effect rises with the magnetization indicating intrinsic ferromagnetism and a certain degree of spin polarization. As the ferromagnetism disappears with rising charge carrier density the ferromagnetic interaction cannot be mediated by the conduction electrons. A more precise evaluation of the magnetoelectric results shows that there is an additional conducting impurity band which could even be spinpolarized. So there are indications that the ferromagnetism is due to magnetic polarons. Some of the structural and magnetometric results as well as the electron spin resonance measurements suggest an additional extrinsic contribution

Structure, magnetic, and electrical properties of Zn1-xMnxO material

Science.gov (United States)

Sebayang, P.; Hulu, S. F.; Nasruddin, Aryanto, D.; Kurniawan, C.; Subhan, A.; Sudiro, T.; Ginting, M.

2017-07-01

ZnO and MnO2 powder were synthesized using solid state reaction method to produce Zn1-xMnxO materials. Effect of dopant concentrations at the material of Zn1-xMnxO (x = 0.015, 0.02, 0.025) to the change of crystal structure, electrical and magnetic properties was studied. The X-ray diffraction (XRD) result of the samples that were doped with Mn showed a hexagonal wurtzite polycrystalline structure. The addition of Mn dopant resulting the decrease of lattice parameters and peaks intensity. The significant increase of the peak intensity occurred at x = 0.02, which also indicated an increase in the crystal quality of ZnO. The change of the ZnO structure affected the electrical and magnetic properties of the samples.

Effect of Cr doping on structural and magnetic properties of ZnS nanoparticles

International Nuclear Information System (INIS)

Virpal,; Singh, Jasvir; Sharma, Sandeep; Singh, Ravi Chand

2016-01-01

The structural, optical and magnetic properties of pure and Cr doped ZnS nanoparticles were studied at room temperature. X-ray diffraction analysis confirmed the absence of any mixed phase and the cubic structure of ZnS in pure and Cr doped ZnS nanoparticles. Fourier transfer infrared spectra confirmed the Zn-S stretching bond at 664 cm"−"1 of ZnS in all prepared nanoparticles. The UV-Visible absorption spectra showed blue shift which became even more pronounced in Cr doped ZnS nanoparticles. However, at relatively higher Cr concentrations a slower red shift was shown by the doped nanoparticles. This phenomenon is attributed to sp-d exchange interaction that becomes prevalent at higher doping concentrations. Further, magnetic hysteresis measurements showed that Cr doped ZnS nanoparticles exhibited ferromagnetic behavior at room temperature.

Influence of the Ionic Liquid Type on the Gel Polymer Electrolytes Properties

Directory of Open Access Journals (Sweden)

Juan P. Tafur

2015-11-01

Full Text Available Gel Polymer Electrolytes (GPEs composed by ZnTf2 salt, poly(vinylidene fluoride-co-hexafluoropropylene (PVdF-HFP, and different ionic liquids are synthesized using n-methyl-2-pyrrolidone (NMP as solvent. Three different imidazolium-based ionic liquids containing diverse cations and anions have been explored. Structural and electrical properties of the GPEs varying the ZnTf2 concentration are analyzed by ATR-FTIR, DSC, TG, and cyclic voltammetry. Free salt IL-GPEs present distinct behavior because they are influenced by the different IL cations and anions composition. However, inclusion of ZnTf2 salt inside the polymers provide GPEs with very similar characteristics, pointing out that ionic transport properties are principally caused by Zn2+ and triflate movement. Whatever the IL used, the presence of NMP solvent inside the polymer’s matrix turns out to be a key factor for improving the Zn2+ transport inside the GPE due to the interaction between Zn2+ cations and carbonyl groups of the NMP. High values of ionic conductivity, low activation energy values, and good voltammetric reversibility obtained regardless of the ionic liquid used enable these GPEs to be applied in Zn batteries. Capacities of 110–120 mAh·g−1 have been obtained for Zn/IL-GPE/MnO2 batteries discharged at −1 mA·cm−2.

Magnetism in Sc-doped ZnO with zinc vacancies: A hybrid density functional and GGA + U approaches

KAUST Repository

Kanoun, Mohammed; Goumri-Said, Souraya; Schwingenschlö gl, Udo; Manchon, Aurelien

2012-01-01

We investigate the zinc vacancy effects on the electronic structures and magnetic properties of Sc-doped ZnO, by performing first-principles calculations within both GGA + U and Heyd-Scuseria-Ernzerhof hybrid functional methods. We find that Sc impurities stabilize considerably Zn vacancies. The electronic and magnetic analysis shows a half metallic ferromagnetic character with a total magnetic moment of 2.01 μ B. The magnetism mainly stems from the O 2p states around the Zn vacancies. Calculations with the hybrid density functional agree with the GGA + U results but give an accurate description of the electronic structure for pure ZnO and Sc-doped ZnO with Zn vacancies. © 2012 Elsevier B.V. All rights reserved.

Magnetism in Sc-doped ZnO with zinc vacancies: A hybrid density functional and GGA + U approaches

KAUST Repository

Kanoun, Mohammed

2012-04-01

We investigate the zinc vacancy effects on the electronic structures and magnetic properties of Sc-doped ZnO, by performing first-principles calculations within both GGA + U and Heyd-Scuseria-Ernzerhof hybrid functional methods. We find that Sc impurities stabilize considerably Zn vacancies. The electronic and magnetic analysis shows a half metallic ferromagnetic character with a total magnetic moment of 2.01 μ B. The magnetism mainly stems from the O 2p states around the Zn vacancies. Calculations with the hybrid density functional agree with the GGA + U results but give an accurate description of the electronic structure for pure ZnO and Sc-doped ZnO with Zn vacancies. © 2012 Elsevier B.V. All rights reserved.

Dielectric and magnetic properties of (Zn, Co) co-doped SnO2 nanoparticles

International Nuclear Information System (INIS)

Rajwali, Khan; Fang Ming-Hu

2015-01-01

Polycrystalline samples of (Zn, Co) co-doped SnO 2 nanoparticles were prepared using a co-precipitation method. The influence of (Zn, Co) co-doping on electrical, dielectric, and magnetic properties was studied. All of the (Zn, Co) co-doped SnO 2 powder samples have the same tetragonal structure of SnO 2 . A decrease in the dielectric constant was observed with the increase of Co doping concentration. It was found that the dielectric constant and dielectric loss values decrease, while AC electrical conductivity increases with doping concentration and frequency. Magnetization measurements revealed that the Co doping SnO 2 samples exhibits room temperature ferromagnetism. Our results illustrate that (Zn, Co) co-doped SnO 2 nanoparticles have an excellent dielectric, magnetic properties, and high electrical conductivity than those reported previously, indicating that these (Zn, Co) co-doped SnO 2 materials can be used in the field of the ultrahigh dielectric material, high frequency device, and spintronics. (paper)

Synthesis of Zn{sup 2+} substituted maghemite nanoparticles and investigation of their structural and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Mozaffari, M. [Department of Physics, Faculty of Science, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of); Shatooti, S. [Department of Physics, Razi University, Kermanshah 67149-67346 (Iran, Islamic Republic of); Jafarzadeh, M., E-mail: mjafarzadeh1027@yahoo.com [Faculty of Chemistry, Razi University, Kermanshah 67149-67346 (Iran, Islamic Republic of); Niyaifar, M. [Department of Physics, Ahvaz Branch, Islamic Azad University, Ahvaz (Iran, Islamic Republic of); Aftabi, A. [Department of Physics, University of Kurdistan, Sanandaj 66177-15175 (Iran, Islamic Republic of); Mohammadpour, H. [Department of Physics, Ahvaz Branch, Islamic Azad University, Ahvaz (Iran, Islamic Republic of); Amiri, Sh. [Department of Physics, Razi University, Kermanshah 67149-67346 (Iran, Islamic Republic of)

2015-05-15

Maghemite and Zn{sup 2+} substituted maghemite (γ-Fe{sub 2−y} Zn{sub 3y/2}O{sub 3}, y=0.0, 0.11, 0.24, 0.36, 0.50 and 0.66) nanoparticles were prepared by coprecipitation method. The effect of Zn{sup 2+} substitution on the structural, morphological and magnetic properties of the nanoparitcles were studied by different techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), magnetometry, magnetic thermogravimetry and Mössbauer spectroscopy. The results of XRD showed that all samples have spinel structure with an increase in lattice parameter by increasing the content of Zn{sup 2+}. FTIR spectra were proved the synthesis of maghemite and Zn{sup 2+} substituted maghemite with appearance of the related absorption bands and band shift upon Zn{sup 2+} substitution. Morphological studies by FESEM demonstrated that the nanoparticles were uniform and spherical with average particle size in range of 20–24 nm. Room temperature magnetic measurements showed that as Zn{sup 2+} content increases, saturation magnetization initially increase up to 75.34 emu/g for y=0.11 and then decrease to 3.65 emu/g for y=0.66, due to substitution of magnetic Fe{sup 3+} by non-magnetic Zn{sup 2+}. Decrease in Curie temperature of the samples, from 510 for maghemite to 250 °C for y=0.36, by increasing the Zn{sup 2+} substitution was a result of reduction of superexchange interactions between different sites. Then, the Curie temperature increased up to 680 °C for y=0.66 which was due to migration of some Zn{sup 2+} ions from A to B sites in the structure of spinel. Room temperature Mössbauer spectra exhibited that the sample with y=0.0 was superparamagnetic, while by increasing the content of Zn{sup 2+}, relaxation effect increased by weakening of A–B exchange interaction. - Highlights: • Synthesis of Zn{sup 2+}-substituted maghemite via co-precipitation/oxidation method. • Increase in lattice

Structural and magnetic depth profiles of magneto-ionic heterostructures beyond the interface limit

Energy Technology Data Exchange (ETDEWEB)

Gilbert, DA; Grutter, AJ; Arenholz, E; Liu, K; Kirby, BJ; Borchers, JA; Maranville, BB

2016-07-22

Electric field control of magnetism provides a promising route towards ultralow power information storage and sensor technologies. The effects of magneto-ionic motion have been prominently featured in the modification of interface characteristics. Here, we demonstrate magnetoelectric coupling moderated by voltage-driven oxygen migration beyond the interface in relatively thick AlO_x/GdO_x/Co(15 nm) films. Oxygen migration and Co magnetization are quantitatively mapped with polarized neutron reflectometry under electro-thermal conditioning. The depth-resolved profiles uniquely identify interfacial and bulk behaviours and a semi-reversible control of the magnetization. Magnetometry measurements suggest changes in the microstructure which disrupt long-range ferromagnetic ordering, resulting in an additional magnetically soft phase. X-ray spectroscopy confirms changes in the Co oxidation state, but not in the Gd, suggesting that the GdO_x transmits oxygen but does not source or sink it. These results together provide crucial insight into controlling magnetism via magneto-ionic motion, both at interfaces and throughout the bulk of the films.

Magnetic study of nanocrystalline 0.95MnO/0.05ZnO

International Nuclear Information System (INIS)

Guskos, N.; Dudek, M.; Zolnierkiewicz, G.; Typek, J.; Berczynski, P.; Lendzion-Bielun, Z.; Sibera, D.; Narkiewicz, U.

2013-01-01

Nanocrystalline 0.95MnO/0.05ZnO sample has been prepared by coprecipitation and calcination processes. X-ray diffraction showed the presence of Mn 3 O 4 nanocrystallites with an average size of 43 nm. Magnetic properties of the 0.95MnO/0.05ZnO sample have been investigated by dc magnetization and magnetic resonances (electron paramagnetic resonance (EPR), ferromagnetic resonance (FMR)) methods. The magnetization study has shown the presence of dominating Mn 3 O 4 paramagnetic and ferrimagnetic (below 46 K) phases. The blocking temperature determined from magnetization measurements was 41 K. An FMR study has shown the evidence of the spread of nanoparticles sizes. An EPR signal from paramagnetic phase of Mn 3 O 4 was observed at temperatures above 45 K and from defects/spurious phases in the low temperature range (T<16 K). Magnetic anisotropies of the sample in the FMR spectra were taken into account by fitting the observed spectra by two lines corresponding to parallel and perpendicular orientations of nanoparticles in an applied magnetic field. - Highlights: ► Magnetic properties of 0.95MnO/0.05ZnO have been studied by dc magnetization and magnetic resonance. ► FMR and EPR spectra were identified and attributed to various spin systems. ► From the spread of blocking temperatures obtained from magnetic resonance the spread of nanoparticles sizes was estimated.

Correlating structural, magnetic, and luminescence properties with the cation distribution of Co{sub 0.5}Zn{sub 0.5+x}Fe{sub 2–x}O{sub 4} nanoferrite

Energy Technology Data Exchange (ETDEWEB)

Wahba, Adel Maher, E-mail: a_m_wahba@yahoo.co.uk [Department of Engineering Physics and Mathematics, Faculty of Engineering, Tanta University (Egypt); Mohamed, Mohamed Bakr [Ain shams University, Faculty of Science, Physics Department, Cairo (Egypt); Imam, N.G. [Experimental Physics Department, Nuclear Research Center, Atomic Energy Authority, 13759 Cairo (Egypt)

2016-06-15

Structural, magnetic, and luminescence properties have been investigated for Co{sub 0.5}Zn{sub 0.5+x}Fe{sub 2−x}O{sub 4} nanoferrite (0.0≤x≤0.4, with a step increment of 0.1) prepared by citrate autocombustion method. X-ray diffraction (XRD) patterns and Fourier-transform infrared (FTIR) spectra proved the formation of a pure cubic spinel phase for all AP samples. Although the ionic radius of Zn{sup 2+} is larger than that of either Fe{sup 3+} or Co{sup 2+}, Rietveld analysis showed that the lattice parameter mostly decreases with increasing Zn substitution. The crystallite size of AP samples decreases gradually with increasing Zn substitution from 16 to 10 nm, which is confirmed with high-resolution (HRTEM) micrographs. Magnetic parameters such as saturation magnetization, coercivity, and remanent field obtained from vibrating sample magnetometry (VSM) revealed a strong dependence on the cation distribution being proposed according to the experimental data of XRD, FTIR, and VSM. The cation distribution indicated that introduced nonstoichiometry is compensated by oxidizing Co{sup 2+} into Co{sup 3+}, which explains the trend of the lattice parameter with increasing x. The distribution of Fe{sup 3+} ions between octahedral and tetrahedral sites was further confirmed by photoluminescence (PL) emission spectra. - Highlights: • Co{sub 0.5}Zn{sub 0.5+x}Fe{sub 2−x}O{sub 4} nanoferrites have been prepared by citrate-precursor method. • XRD peaks and IR bands confirmed pure spinel structure for all samples. • Structural, magnetic, and optical properties depend on the cation distribution. • A cation distribution was proposed based on the experimental data.

Fabrication of CoZn alloy nanowire arrays: Significant improvement in magnetic properties by annealing process

International Nuclear Information System (INIS)

Koohbor, M.; Soltanian, S.; Najafi, M.; Servati, P.

2012-01-01

Highlights: ► Increasing the Zn concentration changes the structure of NWs from hcp to amorphous. ► Increasing the Zn concentration significantly reduces the Hc value of NWs. ► Magnetic properties of CoZn NWs can be significantly enhanced by appropriate annealing. ► The pH of electrolyte has no significant effect on the properties of the NW arrays. ► Deposition frequency has considerable effects on the magnetic properties of NWs. - Abstract: Highly ordered arrays of Co 1−x Zn x (0 ≤ x ≤ 0.74) nanowires (NWs) with diameters of ∼35 nm and high length-to-diameter ratios (up to 150) were fabricated by co-electrodeposition of Co and Zn into pores of anodized aluminum oxide (AAO) templates. The Co and Zn contents of the NWs were adjusted by varying the ratio of Zn and Co ion concentrations in the electrolyte. The effect of the Zn content, electrodeposition conditions (frequency and pH) and annealing on the structural and magnetic properties (e.g., coercivity (Hc) and squareness (Sq)) of NW arrays were investigated using X-ray diffraction (XRD), scanning electron microscopy, electron diffraction, and alternating gradient force magnetometer (AGFM). XRD patterns reveal that an increase in the concentration of Zn ions of the electrolyte forces the hcp crystal structure of Co NWs to change into an amorphous phase, resulting in a significant reduction in Hc. It was found that the magnetic properties of NWs can be significantly improved by appropriate annealing process. The highest values for Hc (2050 Oe) and Sq (0.98) were obtained for NWs electrodeposited using 0.95/0.05 Co:Zn concentrations at 200 Hz and annealed at 575 °C. While the pH of electrolyte is found to have no significant effect on the structural and magnetic properties of the NW arrays, the electrodeposition frequency has considerable effects on the magnetic properties of the NW arrays. The changes in magnetic property of NWs are rooted in a competition between shape anisotropy and

Defect mediated magnetic interaction and high Tc ferromagnetism in Co doped ZnO nanoparticles.

Science.gov (United States)

Pal, Bappaditya; Giri, P K

2011-10-01

Structural, optical and magnetic studies have been carried out for the Co-doped ZnO nanoparticles (NPs). ZnO NPs are doped with 3% and 5% Co using ball milling and ferromagnetism (FM) is studied at room temperature and above. A high Curie temperature (Tc) has been observed from the Co doped ZnO NPs. X-ray diffraction and high resolution transmission electron microscopy analysis confirm the absence of metallic Co clusters or any other phase different from würtzite-type ZnO. UV-visible absorption and photoluminescence studies on the doped samples show change in band structure and oxygen vacancy defects, respectively. Micro-Raman studies of doped samples shows defect related additional strong bands at 547 and 574 cm(-1) confirming the presence of oxygen vacancy defects in ZnO lattice. The field dependence of magnetization (M-H curve) measured at room temperature exhibits the clear M-H loop with saturation magnetization and coercive field of the order of 4-6 emu/g and 260 G, respectively. Temperature dependence of magnetization measurement shows sharp ferromagnetic to paramagnetic transition with a high Tc = 791 K for 3% Co doped ZnO NPs. Ferromagnetic ordering is interpreted in terms of overlapping of polarons mediated through oxygen vacancy defects based on the bound magnetic polaron (BMP) model. We show that the observed FM data fits well with the BMP model involving localised carriers and magnetic cations.

Effects of Temperature on the Microstructure and Magnetic Property of Cr-Doped ZnO DMS Prepared by Hydrothermal Route Assisted by Pulsed Magnetic Fields

Directory of Open Access Journals (Sweden)

Shiwei Wang

2013-01-01

Full Text Available In the present work, Cr-doped ZnO diluted magnetic semiconductor was synthesized by hydrothermal method under pulsed magnetic fields. The samples were characterized by XRD, SEM, VSM, Raman, and XPS techniques. Results demonstrated that Zn ions in the ZnO crystal lattice were partially displaced by Chromium (III ions. All samples show room temperature ferromagnetism which was enhanced by pulsed magnetic fields. The mechanism of ferromagnetism of Cr-doped ZnO particles was discussed.

Influence of Zn/Fe Molar Ratio on Optical and Magnetic Properties of ZnO and ZnFe2O4 Nanocrystal as Calcined Products of Layered Double Hydroxides

Directory of Open Access Journals (Sweden)

Abdullah Ahmed Ali Ahmed

2014-01-01

Full Text Available The coprecipitation method has been used to synthesize layered double hydroxide (Zn-Fe-LDH nanostructure at different Zn2+/Fe3+ molar ratios. The structural properties of samples were studied using powder X-ray diffraction (PXRD. LDH samples were calcined at 600°C to produce mixed oxides (ZnO and ZnFe2O4. The crystallite size of mixed oxide was found in the nanometer scale (18.1 nm for ZnFe2O4 and 43.3 nm for ZnO. The photocatalytic activity of the calcination products was investigated using ultraviolet-visible-near infrared (UV-VIS-NIR diffuse reflectance spectroscopy. The magnetic properties of calcined LDHs were investigated using a vibrating sample magnetometer (VSM. The calcined samples showed a paramagnetic behavior for all Zn2+/Fe3+ molar ratios. The effect of molar ratio on magnetic susceptibility of the calcined samples was also studied.

Fabrication and Properties of Iron-based Soft Magnetic Composites Coated with NiZnFe2O4

Directory of Open Access Journals (Sweden)

WU Shen

2017-07-01

Full Text Available This paper focuses on iron-based soft magnetic composites which were synthesized by utilizing the sol-gel method prepared Ni-Zn ferrite particles as insulating compound to coat iron powder, and the influence of NiZnFe2O4 content and molding pressure on the magnetic properties was studied. The morphology, magnetic properties and density of Ni-Zn ferrite insulated compacts were investigated. Scanning electron microscope,line-scan EDX analysis and distribution maps show that the iron particle surface is covered with a thin layer of uniform Ni-Zn ferrites. The existing of the insulating layer can effectively improve the electrical resistivity of soft magnetic composites. Magnetic measurements show that the real part of permeability decreases with the increase of the Ni-Zn ferrite content, and the sample with 3%(mass fraction, the same below Ni-Zn ferrite has an acceptable real part and minimum imaginary part of permeability in comparison with other samples. Results show that the addition of NiZnFe2O4 can dramatically decrease the internal magnetic loss, the magnetic loss of coated samples decreases by 83.8% as compared with that of uncoated samples at 100kHz. The density of the Fe-3%NiZnFe2O4 compacts reaches 7.14g/cm3 and the saturation magnetization is 1.47T when the molding pressure is 1000MPa.

Magnetic Properties of Ni-Zn Ferrite Prepared with the Layered Precursor Method

International Nuclear Information System (INIS)

Zhou Xin; Hou Zhi-Ling; Li Feng; Qi Xin

2010-01-01

We prepare NiZnFe 2 O 4 soft magnetic ferrites with different molar ratios with the layered precursor method and investigate their magnetic properties. In the layered precursor, metal ions are scattered on the layer plate in a certain way on account of the effect of lowest lattice energy and lattice orientation. After high temperature calcinations, spinel ferrites with uniform structural component and single magnetic domain can be obtained, and the magnetic property is improved greatly. NiZnFe 2 O 4 ferrites prepared have the best specific saturation magnetization of 79.15 emu·g −1 , higher than that of 68 emu·g −1 prepared by the chemical co-precipitation method and that of 59 emu·g −1 prepared by the emulsion-gel method. Meanwhile the coercivity of NiZnFe 2 O 4 ferrites prepared by layered precursor method is 14 kA·m −1 , lower than that of 50 emu·g −1 prepared by the co-precipitation method and that of 59 emu·g −1 prepared by the emulsion-gel method. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

A treatise on first-principles studies of ZnO as diluted magnetic semiconductor

Energy Technology Data Exchange (ETDEWEB)

Nayak, Sanjeev Kumar

2012-04-24

The scope of the present thesis is to study the properties of ZnO doped with transition metal elements by the density functional theory (DFT).cc In this thesis, there is extensive study of the electronic structure of ZnO beyond the generalized gradient approximation (GGA) as exchange-correlation functional (E{sub xc}), which is well known to be associated with some drawback in predicting the semiconducting properties. One of the methods adopted for improvement is by adding extra correlation-energy to GGA (GGA+U) in line with the Hubbard model. We find that with adding U on Zn d-orbitals, the band gap improves with simultaneous shift of the Zn d-bands to lower energies. The band gap nevertheless is still far below the experimental value. Another approach to correct for the E{sub xc} is by the treatment of screened hybrid-functionals proposed by Heyd-Scuseria-Ernzerhof (HSE), where the contribution to the exchange energy is through the blend of some percentage of screened Hartree-Fock exchange and rest from the GGA exchange. The correlation energy is derived from GGA. This method also has limitations in describing the electronic structure of ZnO. A simple proposition of mixing the GGA+U and the hybrid-functional treatment may be a solution, which has been investigated in this work. The band structure of ZnO has been compared for various level of theory for E{sub xc}, namely, LDA, GGA, GGA+U, and HSE functionals with different screening lengths ({omega}). A proposal for HSE+U functionals has been been put forward and supported. Using some of the treatments for E{sub xc} as stated above, the magnetic properties of TM(Cr, Mn, Fe, Co, and Ni) doped ZnO are studied. Firstly, the electronic structure calculations for TM doped ZnO are done with the Korringa-Kohn-Rostoker (KKR) method with the LDA and using the coherent potential approximation (CPA). The exchange integrals are then calculated using the Liechtenstein's formalism, which are then used in the Monte Carlo

Effect of Co content on magnetic and optical properties of Zn1−xCoxOy nanorods

International Nuclear Information System (INIS)

Chen, Jia-Hong; Lin, Yow-Jon; Chang, Hsing-Cheng; Chen, Ya-Hui; Horng, Lance; Chang, Chia-Chi

2013-01-01

Highlights: ► The magnetic and optical properties of Zn 1−x Co x O y nanorods were studied. ► The ferromagnetic properties arise from the replacement of Zn by Co and defects. ► A link between the magnetization, nanorod sizes and defects was established. - Abstract: The effect of Co content on the magnetic and optical properties of Zn 1−x Co x O y nanorods have been investigated in this study. X-ray diffraction, energy dispersive spectrometer, photoluminescence and ferromagnetism measurements were used to characterize the Zn 1−x Co x O y nanorods. It is shown that the ferromagnetic properties arise from the replacement of Zn by Co in the ZnO lattice. Combining with photoluminescence and scanning electron microscopic results, a direct link between the magnetization, nanorod sizes and acceptor defects of Zn 1−x Co x O y nanorods was established.

Hydrothermal synthesis and magnetic properties of Mn doped ZnS nanoparticles

Science.gov (United States)

Rashad, M. M.; Rayan, D. A.; El-Barawy, K.

2010-01-01

Nanocrystallite Mn doped Zn1-XS (X = 0 to 0.4) powders have been synthesized through a hydrothermal route. The effect of the hydrothermal temperature and Mn2+ ions substitution on the crystal structure, crystallite size, microstructure and magnetic properties were investigated using (XRD), (SEM) and (VSM). The results revealed that wurtzite zinc sulfide phase was formed using thiourea as a sulfur source at temperature 150- 200oC for 24 h. The crystallite size was (7.9-15.1 nm) was obtained at the same conditions. The doping of Mn2+ ions decreased the crystallite size of the formed ZnS wurtzite phase was in the range between 7.9 and 3.8 nm. SEM micrographs showed that the produced ZnS and Mn doped ZnS particles were appeared as spherical shape. The magnetic properties were improved by substitution of Mn2+ ions up to 0.2.

Hydrothermal synthesis and magnetic properties of Mn doped ZnS nanoparticles

International Nuclear Information System (INIS)

Rashad, M M; Rayan, D A; El-Barawy, K

2010-01-01

Nanocrystallite Mn doped Zn 1-X S (X = 0 to 0.4) powders have been synthesized through a hydrothermal route. The effect of the hydrothermal temperature and Mn 2+ ions substitution on the crystal structure, crystallite size, microstructure and magnetic properties were investigated using (XRD), (SEM) and (VSM). The results revealed that wurtzite zinc sulfide phase was formed using thiourea as a sulfur source at temperature 150- 200 o C for 24 h. The crystallite size was (7.9-15.1 nm) was obtained at the same conditions. The doping of Mn 2+ ions decreased the crystallite size of the formed ZnS wurtzite phase was in the range between 7.9 and 3.8 nm. SEM micrographs showed that the produced ZnS and Mn doped ZnS particles were appeared as spherical shape. The magnetic properties were improved by substitution of Mn 2+ ions up to 0.2.

Hot-injection synthesis of Ni-ZnO hybrid nanocrystals with tunable magnetic properties and enhanced photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Zeng, Deqian; Qiu, Yulong; Chen, Yuanzhi, E-mail: yuanzhi@xmu.edu.cn; Zhang, Qinfu; Liu, Xiang; Peng, Dong-Liang, E-mail: dlpeng@xmu.edu.cn [Xiamen University, Department of Materials Science and Engineering, Fujian Provincial Key Laboratory of Materials Genome, Collaborative Innovation Center of Chemistry for Energy Materials, College of Materials (China)

2017-04-15

Magnetic metal-semiconductor hybrid nanocrystals containing ferromagnetic Ni and semiconductor ZnO have been prepared via a hot-injection route. The Ni-ZnO hybrid nanocrystals have a flower-like morphology that consists of Ni inner cores and ZnO petal shells. In spite of their large lattice mismatch, ZnO nanocrystals can still grow on faceted Ni nanocrystals to form stable interfaces. The composition of Ni-ZnO hybrid nanocrystals is readily controlled, and the average size of Ni core is tunable from 25 to 50 nm. Room temperature ferromagnetic properties are observed in these hybrid nanocrystals, and tunable magnetic properties also can be achieved by varying the size of Ni core. The as-prepared Ni-ZnO hybrid nanocrystals exhibit enhanced photocatalytic performance under ultraviolet light illumination as compared to pure ZnO nanocrystals. Furthermore, the superior reusability of hybrid nanocrystals for photocatalytic application is achieved by virtue of their magnetic properties. The facile and efficient seed-mediate strategy is particularly attractive to construct hybrid magnetic-semiconducting heterostructures. The as-obtained Ni-ZnO hybrid nanocrystals offer great potential for various applications due to their combined magnetic and semiconducting properties and low-cost earth-abundant availability.

Magnetic and optical properties of Zn{sup 2+} ion substituted barium hexaferrites

Energy Technology Data Exchange (ETDEWEB)

Baykal, A., E-mail: hbaykal@fatih.edu.tr [EYRA Textile Chemicals and Chemical Industry Trade Company, Saraçlar Industrial Zone, No: 3-12, 34490 İkitelli, İstanbul (Turkey); Auwal, I.A. [Department of Chemistry, Sule Lamido University, P.M.B 048, Kafin Hausa, Jigawa State (Nigeria); Güner, S. [Department of Physics, Fatih University, 34500 B.Çekmece, İstanbul (Turkey); Sözeri, H. [TÜBITAK – UME, National Metrology Institute, 41470 Gebze, Kocaeli (Turkey)

2017-05-15

Ba{sub 1−x}Zn{sub x}Fe{sub 12}O{sub 19} (0.0≤x≤0.3) hexaferrites were produced via sol-gel auto combustion technique. XRD patterns show that all the samples are single-phase M-type barium hexaferrite (BaM). Scanning electron microscopy (SEM) revealed that grains have a size range of 0.5–2 µm. The magnetic hysteresis (σ-H) loops revealed the ferromagnetic nature of NPs. The average crystallite sizes were calculated by applying Scherrer equation on the base of XRD powder patterns of all samples and found to be in the range of 16.78–48.34 nm. In particular, Ba{sub 1−x}Zn{sub x}Fe{sub 12}O{sub 19} (0.0≤x≤0.3) hexaferrites have suitable magnetic characteristics (saturation magnetization in a range of 63.00–67.70 emu/g and coercive field in a range of 822–1275 Oe) for magnetic recording and permanent magnets. Effective crystalline anisotropy constants (K{sub eff}) are between 4.20×10{sup 5} and 4.84×10{sup 5} Erg/g. Magnetic moment increased by the substitution of non-magnetic Zn{sup 2+} ions. The anisotropy field (H{sub a}) or intrinsic coercivity values above 13255 Oe reveals that all samples are magnetically hard materials. Tauc plots were drawn to specify the direct optical energy band gap (E{sub g}) of NPs. The E{sub g} values are in a narrow range between 1.69 eV and 1.76 eV. - Highlights: • Diamagnetic Zn{sup 2+} ionsubstitution on magnetic and optical properties of barium hexaferrite has been investigated. • All products are ferromagnetic. • The grain sizes are much larger than the critical dimension of 431 nm to exhibit single-domain nature.

Magnetically addressable fluorescent Fe3O4/ZnO nanocomposites: Structural, optical and magnetization studies

Science.gov (United States)

Roychowdhury, A.; Pati, S. P.; Mishra, A. K.; Kumar, S.; Das, D.

2013-06-01

Fe3O4/ZnO nanocomposites (NCs) are prepared by a wet chemical route. X-ray diffraction, transmission electron microscopy and Fourier transform infrared spectroscopy studies confirm the coexistence of Fe3O4 and ZnO phases in the NCs. The UV-vis absorption spectra show a red shift of the absorption peak with increase in Fe3O4 content indicating a modification of the band structure of ZnO in the NCs. Photoluminescence emission spectra of the NCs display strong excitonic emission in the UV region along with weak emission bands in the visible range caused by electronic transitions involving defect-related energy levels in the band gap of ZnO. Positron annihilation lifetimes indicate that cation vacancies in the ZnO structure are the strong traps for positrons and the overall defect concentration in the NCs decreases with increase in Fe3O4 content. Dc magnetization measurements reveal an anomalous temperature dependence of the coercivity of the NCs that is argued to be due to the anomalous variation of magnetocrystalline anisotropy at lower temperature. The irreversibility observed in the temperature dependent ZFC-FC magnetization points to the presence of a spin-glass phase in the NCs.

Fabrication of CoZn alloy nanowire arrays: Significant improvement in magnetic properties by annealing process

Energy Technology Data Exchange (ETDEWEB)

Koohbor, M. [Department of Physics, University of Kurdistan, Sanandaj (Iran, Islamic Republic of); Soltanian, S., E-mail: s.soltanian@gmail.com [Department of Physics, University of Kurdistan, Sanandaj (Iran, Islamic Republic of); Department of Electrical and Computer Engineering, University of British Columbia, Vancouver (Canada); Najafi, M. [Department of Physics, University of Kurdistan, Sanandaj (Iran, Islamic Republic of); Department of Physics, Hamadan University of Technology, Hamadan (Iran, Islamic Republic of); Servati, P. [Department of Electrical and Computer Engineering, University of British Columbia, Vancouver (Canada)

2012-01-05

Highlights: Black-Right-Pointing-Pointer Increasing the Zn concentration changes the structure of NWs from hcp to amorphous. Black-Right-Pointing-Pointer Increasing the Zn concentration significantly reduces the Hc value of NWs. Black-Right-Pointing-Pointer Magnetic properties of CoZn NWs can be significantly enhanced by appropriate annealing. Black-Right-Pointing-Pointer The pH of electrolyte has no significant effect on the properties of the NW arrays. Black-Right-Pointing-Pointer Deposition frequency has considerable effects on the magnetic properties of NWs. - Abstract: Highly ordered arrays of Co{sub 1-x}Zn{sub x} (0 {<=} x {<=} 0.74) nanowires (NWs) with diameters of {approx}35 nm and high length-to-diameter ratios (up to 150) were fabricated by co-electrodeposition of Co and Zn into pores of anodized aluminum oxide (AAO) templates. The Co and Zn contents of the NWs were adjusted by varying the ratio of Zn and Co ion concentrations in the electrolyte. The effect of the Zn content, electrodeposition conditions (frequency and pH) and annealing on the structural and magnetic properties (e.g., coercivity (Hc) and squareness (Sq)) of NW arrays were investigated using X-ray diffraction (XRD), scanning electron microscopy, electron diffraction, and alternating gradient force magnetometer (AGFM). XRD patterns reveal that an increase in the concentration of Zn ions of the electrolyte forces the hcp crystal structure of Co NWs to change into an amorphous phase, resulting in a significant reduction in Hc. It was found that the magnetic properties of NWs can be significantly improved by appropriate annealing process. The highest values for Hc (2050 Oe) and Sq (0.98) were obtained for NWs electrodeposited using 0.95/0.05 Co:Zn concentrations at 200 Hz and annealed at 575 Degree-Sign C. While the pH of electrolyte is found to have no significant effect on the structural and magnetic properties of the NW arrays, the electrodeposition frequency has considerable effects on

Zn2+ and Sr2+ Adsorption at the TiO2 (110)-Electrolyte Interface: Influence of Ionic Strength, Coverage, and Anions

International Nuclear Information System (INIS)

Zhang, Z.; Fenter, P.; Cheng, L.; Sturchio, N.; Bedzyk, M.; Machesky, M.; Anovitz, L.; Wesolowski, D.

2006-01-01

The X-ray standing wave technique was used to probe the sensitivity of Zn 2+ and Sr 2+ ion adsorption to changes in both the adsorbed ion coverage and the background electrolyte species and concentrations at the rutile (α-TiO 2 ) (110)-aqueous interface. Measurements were made with various background electrolytes (NaCl, NaTr, RbCl, NaBr) at concentrations as high as 1 m. The results demonstrate that Zn 2+ and Sr 2+ reside primarily in the condensed layer and that the ion heights above the Ti-O surface plane are insensitive to ionic strength and the choice of background electrolyte (with - , coupled with the insensitivity of Zn 2+ and Sr 2+ cation heights to changes in the background electrolyte, implies that anions do not play a significant role in the adsorption of these divalent metal ions to the rutile (110) surface. Absolute ion coverage measurements for Zn 2+ and Sr 2+ show a maximum Stern-layer coverage of ∼0.5 monolayer, with no significant variation in height as a function of Stern-layer coverage. These observations are discussed in the context of Gouy-Chapman-Stern models of the electrical double layer developed from macroscopic sorption and pH-titration studies of rutile powder suspensions. Direct comparison between these experimental observations and the MUltiSIte Complexation (MUSIC) model predictions of cation surface coverage as a function of ionic strength revealed good agreement between measured and predicted surface coverages with no adjustable parameters

Mn-doped ZnO nanocrystals synthesized by sonochemical method: Structural, photoluminescence, and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Othman, A.A., E-mail: aaelho@yahoo.com [Assiut University, Faculty of Science, Department of Physics, Assiut 71516 (Egypt); Osman, M.A. [Assiut University, Faculty of Science, Department of Physics, Assiut 71516 (Egypt); Ibrahim, E.M.M. [Sohag University, Faculty of Science, Department of Physics, Sohag 82524 (Egypt); Ali, Manar A.; Abd-Elrahim, A.G. [Assiut University, Faculty of Science, Department of Physics, Assiut 71516 (Egypt)

2017-05-15

Highlights: • Mn-doped ZnO nanostructures were synthesized by the sonochemical method. • Structural, morphological, optical, photoluminescence and magnetic properties were investigated. • Mn-doped ZnO nanostructures reveal a blue shift of the optical band gap. • Photoluminescence spectra of Mn-doped ZnO nanostructures show quenching in the emission intensity. • Mn-doped ZnO nanostructures exhibit ferromagnetic ordering at room temperature. - Abstract: This work reports the synthesis of Mn-doped ZnO nanostructures using ice-bath assisted sonochemical technique. The impact of Mn-doping on structural, morphological, optical, and magnetic properties of ZnO nanostructures is studied. The morphological study shows that the lower doped samples possess mixtures of nanosheets and nanorods while the increase in Mn content leads to improvement of an anisotropic growth in a preferable orientation to form well-defined edge rods at Mn content of 0.04. UV–vis absorption spectra show that the exciton peak in the UV region is blue shifted due to Mn incorporation into the ZnO lattice. Doping ZnO with Mn ions leads to a reduction in the PL intensity due to a creation of more non-radiative recombination centers. The magnetic measurements show that the Mn-doped ZnO nanostructures exhibit ferromagnetic ordering at room temperature, as well as variation of the Mn content can significantly affect the ferromagnetic behavior of the samples.

Magnetic structure evolution in mechanically milled nanostructured ZnFe2O4 particles

DEFF Research Database (Denmark)

Jiang, Jianzhong; Wynn, P.; Mørup, Steen

1999-01-01

Nanostructured partially-inverted ZnFe2O4 particles have been prepared from bulk ZnFe2O4 by high-energy ball milling in an open container. The grain size reduction, cation site distributions, and the evolution of magnetic structures have been studied by x-ray diffraction with Rietveld structure...... refinements, transmission electron microscopy, and Mossbauer spectroscopy. It is found that a change of magnetic structure from an antiferromagnetic to a ferrimagnetic (or ferromagnetic) structure occurs in the milled samples. This change is correlated with the redistribution of the cations, Zn and Fe...

Hydrothermal synthesis and magnetic properties of Mn doped ZnS nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Rashad, M M; Rayan, D A; El-Barawy, K [Central Metallurgical Research and Development Institute PO Box: 87 Helwan, Cairo (Egypt)

2010-01-01

Nanocrystallite Mn doped Zn{sub 1-X}S (X = 0 to 0.4) powders have been synthesized through a hydrothermal route. The effect of the hydrothermal temperature and Mn{sup 2+} ions substitution on the crystal structure, crystallite size, microstructure and magnetic properties were investigated using (XRD), (SEM) and (VSM). The results revealed that wurtzite zinc sulfide phase was formed using thiourea as a sulfur source at temperature 150- 200{sup o}C for 24 h. The crystallite size was (7.9-15.1 nm) was obtained at the same conditions. The doping of Mn{sup 2+} ions decreased the crystallite size of the formed ZnS wurtzite phase was in the range between 7.9 and 3.8 nm. SEM micrographs showed that the produced ZnS and Mn doped ZnS particles were appeared as spherical shape. The magnetic properties were improved by substitution of Mn{sup 2+} ions up to 0.2.

Magnetic properties of sol-gel synthesized C-doped ZnO nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Dung, Nguyen Duc, E-mail: dung.nguyenduc@hust.edu.vn [Advanced Institute of Science and Technology (AIST), Hanoi University of Science and Technology, No.1 Dai Co Viet, Hanoi (Viet Nam); Son, Cao Thai; Loc, Pham Vu; Cuong, Nguyen Huu; Kien, Pham The; Huy, Pham Thanh [Advanced Institute of Science and Technology (AIST), Hanoi University of Science and Technology, No.1 Dai Co Viet, Hanoi (Viet Nam); Ha, Ngo Ngoc [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology, No.1 Dai Co Viet, Hanoi (Viet Nam)

2016-05-25

ZnO doping with Carbon (C-doped ZnO) materials were prepared by sol-gel technique following with a heat treatment process. Single phase of Wurtzite crystal structure of ZnO was concluded via x-ray diffraction (XRD) with a large amount of excess C tracking by energy dispersive X-ray spectroscopy (EDX) analysis. Two types of ZnO crystals (twinning particles) with different grain sizes and shapes were identified via scanning electron microscopy (FE-SEM). The first type has a smaller grain size of about 20 nm and hexagonal shape. And the second type has a larger grain size of about 80–120 nm and round shape. C substitutions of both Zn and O sites to form C–O and C–Zn bonds were conclusively confirmed via x-ray photoelectron spectroscope (XPS). Experimental evidences for the co-existence of different ferromagnetic phases in the materials are reported and discussed. Two Curie points at high temperatures (>500 °C) are presented. A metamagnetic transition was observed at magnetic field H = 19.2 kOe which was related to the co-existence of ferromagnetic phases. These involve in the formation of twinning C-doped ZnO nanoparticles. - Highlights: • Formation of sol-gel prepared single phase wurtzite ZnO nanoparticles. • Two morphological C-doped ZnO nanoparticles of different grain sizes. • The room temperature ferromagnetism. • An abnormal metamagnetic transition at magnetic field H = 19.2 kOe. • Two different Curie points (T{sub C}) at 500–600 °C.

Effect of Al doping on the magnetic and electrical properties of Zn(Cu)O based diluted magnetic semiconductors

Science.gov (United States)

Chakraborti, D.; Trichy, G.; Narayan, J.; Prater, J. T.; Kumar, D.

2007-12-01

The effect of Al doping on the magnetic properties of Zn(Cu)O based dilute magnetic semiconducting thin films has been systematically investigated. Epitaxial thin films have been deposited onto sapphire c-plane single crystals using pulsed laser deposition technique. X-ray diffraction and high resolution transmission electron microscopy studies show that the Zn(Cu,Al)O films are epitaxially grown onto (0001) sapphire substrates with a 30°/90° rotation in the basal plane. The large lattice misfit of the order of 16% is accommodated by matching integral multiples of lattice and substrate planes. In these large mismatch systems, the resulting films are fully relaxed following deposition of the first complete monolayer of ZnO (consistent with a critical thickness that is less than one monolayer). Magnetic hysteresis measurements indicate that the pure Zn(Cu)O thin films are ferromagnetic at room temperature. Doping with up to 5% Al (n type) does not significantly affect the ferromagnetism even though it results in an increase in carrier densities of more than 3 orders of magnitude, rising from 1×1017 to 1.5×1020 cm-3. However, for Al additions above 5%, a drop in net magnetization is observed. Annealing the films in an oxygen atmosphere at 600 °C also resulted in a dramatic drop in magnetic moment of the samples. These results strongly suggest that carrier induced exchange is not directly responsible for the magnetic properties of these materials. Rather, a defect mediated exchange mechanism needs to be invoked for this system.

Spinel ferrite nanocrystals embedded inside ZnO: magnetic, electronic andmagneto-transport properties

Energy Technology Data Exchange (ETDEWEB)

Zhou, Shengqiang; Potzger, K.; Xu, Qingyu; Kuepper, K.; Talut, G.; Marko, D.; Mucklich, A.; Helm, M.; Fassbender, J.; Arenholz, E.; Schmidt, H.

2009-08-21

In this paper we show that spinel ferrite nanocrystals (NiFe{sub 2}O{sub 4}, and CoFe{sub 2}O{sub 4}) can be texturally embedded inside a ZnO matrix by ion implantation and post-annealing. The two kinds of ferrites show different magnetic properties, e.g. coercivity and magnetization. Anomalous Hall effect and positive magnetoresistance have been observed. Our study suggests a ferrimagnet/semiconductor hybrid system for potential applications in magneto-electronics. This hybrid system can be tuned by selecting different transition metal ions (from Mn to Zn) to obtain various magnetic and electronic properties.

Magnetic and structural properties of Zn-doped yttrium iron garnet nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Pena-Garcia, R.; Delgado, A.; Guerra, Y.; Farias, B.V.M.; Martinez, D. [Pos Graduacao em Ciencia de Materiais, Universidade Federal de Pernambuco, Recife, PE (Brazil); Skovroinski, E. [Departamento de Quimica Fundamental, Universidade Federal de Pernambuco, Recife, PE (Brazil); Galembeck, A. [Pos Graduacao em Ciencia de Materiais, Universidade Federal de Pernambuco, Recife, PE (Brazil); Departamento de Quimica Fundamental, Universidade Federal de Pernambuco, Recife, PE (Brazil); Padron-Hernandez, E. [Pos Graduacao em Ciencia de Materiais, Universidade Federal de Pernambuco, Recife, PE (Brazil); Departamento de Fisica, Universidade Federal de Pernambuco, Recife, PE (Brazil)

2016-09-15

Zn-doped YIG was prepared using the sol-gel method with TGA measurements showing the phase formation between 900 and 1000 C. XRD analysis showed close to 1100 C the formation of Franklinite phase, coexisting with the cubic YIG. Y{sub 3}(Fe{sub 1-x}Zn{sub x}){sub 5}O{sub 12} samples with different Zn concentrations (x = 0, 0.01, 0.03, and 0.05) were prepared and analyzed for a magnetic study. A decrease in magnetic moment of the samples was confirmed on increasing the concentration of Zn ions. This decrease is due to the substitution of Fe ions by Zn. This also confirmed the results of XRD showing the linear increase in the lattice parameter. Fittings by Bloch's law shows results compared with those already reported in the literature. The exponent and constant for the Bloch law presented similar values to those reported for YIG doped with other ions. We obtained the parameter α ∝10{sup -6} K{sup -n} with n close to 1.9 for all samples. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Electrospinning direct synthesis of magnetic ZnFe{sub 2}O{sub 4}/ZnO multi-porous nanotubes with enhanced photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Wang, Chunlei [College of Chemistry and Environmental Engineering, Wuhan Polytechnic University, Wuhan 430023 (China); Tan, Xing [College of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023 (China); Yan, Juntao, E-mail: yanjuntaonihao@163.com [College of Chemistry and Environmental Engineering, Wuhan Polytechnic University, Wuhan 430023 (China); Chai, Bo [College of Chemistry and Environmental Engineering, Wuhan Polytechnic University, Wuhan 430023 (China); Li, Jianfen, E-mail: lijfen@163.com [College of Chemistry and Environmental Engineering, Wuhan Polytechnic University, Wuhan 430023 (China); Chen, Shizhong [College of Food Science and Engineering, Wuhan Polytechnic University, Wuhan 430023 (China)

2017-02-28

Highlights: • ZnFe2O4/ZnO heterojunctions are firstly fabricated by electrospinning method. • ZnFe{sub 2}O{sub 4}/ZnO heterojunctions possess multi-porous nanotube structure. • ZnFe{sub 2}O{sub 4}/ZnO heterojunctions can significantly enhance photocatalytic activity. - Abstract: Magnetic ZnFe{sub 2}O{sub 4}/ZnO (ZFO/ZnO) multi-porous nanotubes have been first fabricated via a facile electrospinning and subsequent calcination process. A series of ZFO/ZnO photocatalysts with different ZFO molar content and morphologies are also obtained by varying the molar ratio of Zn/Fe metal salt and its dosage. The morphology, composition, crystal structure and specific surface area of achieved photocatalysts are systematically examined. TEM images demonstrate ZFO/ZnO-3 multi-porous nanotubes possess perfect 1D nanotube profile with hierarchical pores. HRTEM images confirm the formation of ZFO/ZnO heterojunctions. DRS spectra show that ZFO/ZnO-3 multi-porous nanotubes exhibit an enhanced absorption both in UV and visible-light region. PL spectra and photocurrent responses of ZFO/ZnO-3 multi-porous nanotube demonstrated that the photogenerated electrons and holes are effectively separated. Above all, ZFO/ZnO-3 multi-porous nanotubes photocatalysts with a larger specific surface area of 57.79 m{sup 2} g{sup −1} exhibit the best photocatalytic efficiency of 99% after 150 min under the solar irradiation for the decolorization of RhB. Moreover, ZFO/ZnO photocatalysts not only possess magnetic separation property, but also keep a relatively high photocatalytic efficiency even after four cycles, which is beneficial for practical application. In addition, both the formation and potential photocatalytic mechanisms of ZFO/ZnO-3 multi-porous nanotubes are proposed in detail.

Controllable growth and magnetic properties of nickel nanoclusters electrodeposited on the ZnO nanorod template

International Nuclear Information System (INIS)

Tang Yang; Zhao Dongxu; Shen Dezhen; Zhang Jiying; Wang Xiaohua

2009-01-01

The ZnO nanorods were used as a template to fabricate nickel nanoclusters by electrodeposition. The ZnO nanorod arrays act as a nano-semiconductor electrode for depositing metallic and magnetic nickel nanoclusters. The growth sites of Ni nanoclusters could be controlled by adjusting the applied potential. Under -1.15 V the Ni nanoclusters could be grown on the tips of ZnO nanorods. On increasing the potential to be more negative the ZnO nanorods were covered by Ni nanoclusters. The magnetic properties of the electrodeposited Ni nanoclusters also evolved with the applied potentials.

Controllable growth and magnetic properties of nickel nanoclusters electrodeposited on the ZnO nanorod template

Energy Technology Data Exchange (ETDEWEB)

Tang Yang; Zhao Dongxu; Shen Dezhen; Zhang Jiying [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16 East Nan-Hu Road, Open Economic Zone, Changchun 130033 (China); Wang Xiaohua, E-mail: dxzhao2000@yahoo.com.c [National Key Laboratory of High Power Semiconductor Laser, Changchun University of Science and Technology, 7089 WeiXing Road, ChangChun 130022 (China)

2009-12-09

The ZnO nanorods were used as a template to fabricate nickel nanoclusters by electrodeposition. The ZnO nanorod arrays act as a nano-semiconductor electrode for depositing metallic and magnetic nickel nanoclusters. The growth sites of Ni nanoclusters could be controlled by adjusting the applied potential. Under -1.15 V the Ni nanoclusters could be grown on the tips of ZnO nanorods. On increasing the potential to be more negative the ZnO nanorods were covered by Ni nanoclusters. The magnetic properties of the electrodeposited Ni nanoclusters also evolved with the applied potentials.

Enhanced magnetic properties of chemical solution deposited BiFeO3 thin film with ZnO buffer layer

International Nuclear Information System (INIS)

Rajalakshmi, R.; Kambhala, Nagaiah; Angappane, S.

2012-01-01

Highlights: ► Enhanced magnetization of BiFeO 3 is important for strong magnetoelectric coupling. ► BiFeO 3 film with ZnO buffer layer was successfully synthesized by chemical method. ► Magnetization of BiFeO 3 has increased by more than 10 times with ZnO buffer layer. ► A mechanism for enhancement in ferromagnetism of BiFeO 3 film is proposed. - Abstract: Magnetic properties of BiFeO 3 films deposited on Si substrates with and without ZnO buffer layer have been studied in this work. We adopted the chemical solution deposition method for the deposition of BiFeO 3 as well as ZnO films. The x-ray diffraction measurements on the deposited films confirm the formation of crystalline phase of BiFeO 3 and ZnO films, while our electron microscopy measurements help to understand the morphology of few micrometers thick films. It is found that the deposited ZnO film exhibit a hexagonal particulate surface morphology, whereas BiFeO 3 film fully covers the ZnO surface. Our magnetic measurements reveal that the magnetization of BiFeO 3 has increased by more than ten times in BiFeO 3 /ZnO/Si film compared to BiFeO 3 /Si film, indicating the major role played by ZnO buffer layer in enhancing the magnetic properties of BiFeO 3 , a technologically important multiferroic material.

First-principles study of ZnSnAs2-based dilute magnetic semiconductors

Science.gov (United States)

Kizaki, Hidetoshi; Morikawa, Yoshitada

2018-02-01

The electronic structure and magnetic properties of chalcopyrite Zn(Sn,TM)As2 and (Zn,TM)SnAs2 have been investigated by the Korringa-Kohn-Rostoker method combined with the coherent potential approximation within the local spin density approximation, where TM denotes a 3d transition metal element. We find that the half-metallic and high-spin ferromagnetic state can be obtained in Zn(Sn,V)As2, Zn(Sn,Cr)As2, Zn(Sn,Mn)As2, (Zn,V)SnAs2, and (Zn,Cr)SnAs2. The calculated result of Zn(Sn,Mn)As2 is in good agreement with the experimentally observed room-temperature ferromagnetism if we can control selective Mn doping at Sn sites. In addition, (Zn,V)SnAs2 and (Zn,Cr)SnAs2 are predicted to exhibit high-Curie-temperature ferromagnetism.

Magnetic exchange interactions in Mn doped ZnSnAs{sub 2} chalcopyrite

Energy Technology Data Exchange (ETDEWEB)

Bouhani-Benziane, H.; Sahnoun, O. [Laboratoire de Physique Quantique de la Matière et Modélisation Mathématique (LPQ3M), University of Mascara (Algeria); Sahnoun, M., E-mail: sahnoun_cum@yahoo.fr [Laboratoire de Physique Quantique de la Matière et Modélisation Mathématique (LPQ3M), University of Mascara (Algeria); Department of Chemistry, University of Fribourg (Switzerland); Driz, M. [Laboratoire de Sciences des Matériaux (LSM), University of Sidi Bel Abbes (Algeria); Daul, C. [Department of Chemistry, University of Fribourg (Switzerland)

2015-12-15

Accurate ab initio full-potential augmented plane wave (FP-LAPW) electronic calculations within generalized gradient approximation have been performed for Mn doped ZnSnAs{sub 2} chalcopyrites, focusing on their electronic and magnetic properties as a function of the geometry related to low Mn-impurity concentration and the spin magnetic alignment (i.e., ferromagnetic vs antiferromagnetic). As expected, Mn is found to be a source of holes and localized magnetic moments of about 4 µ{sub B} per Mn atom are calculated which are sufficiently large. The defect calculations are firstly performed by replacing a single cation (namely Zn and Sn) with a single Mn atom in the pure chalcopyrite ZnSnAs{sub 2} supercell, and their corresponding formation energies show that the substitution of a Sn atom (rather than Zn) by Mn is strongly favored. Thereafter, a comparison of total energy differences between ferromagnetic (FM) and antiferromagnetic (AFM) are given. Surprisingly, the exchange interaction between a Mn pairs is found to oscillate with the distance between them. Consequently, the AFM alignment is energetically favored in Mn-doped ZnSnAs{sub 2} compounds, except for low impurity concentration associated with lower distances between neighboring Mn impurities, in this case the stabilization of FM increases. Moreover, the ferromagnetic alignment in the Mn-doped ZnSnAs{sub 2} systems behaves half-metallic; the valence band for majority spin orientation is partially filled while there is a gap in the density of states for the minority spin orientation. This semiconducting gap of ~1 eV opened up in the minority channel and is due to the large bonding–antibonding splitting from the p–d hybridization. Our findings suggest that the Mn-doped ZnSnAs{sub 2} chalcopyrites could be a different class of ferromagnetic semiconductors. - Highlights: • ab initio calculations were performed on Mn doped ZnSnAs{sub 2} chalcopyrite. • Substitution of a Sn atom (rather than Zn) by Mn

CdTe deposition by successive ionic layer adsorption and reaction (SILAR) technique onto ZnO nanowires

Energy Technology Data Exchange (ETDEWEB)

Salazar, Raul; Delamoreanu, Alexandru; Saidi, Bilel; Ivanova, Valentina [CEA, LETI, MINATEC Campus, 17 Rue des Martyrs, 38054, Grenoble (France); Levy-Clement, Claude [CNRS, Institut de Chimie et des Materiaux de Paris-Est, 94320, Thiais (France)

2014-09-15

In this study is reported CdTe deposition by Successive Ionic Layer Adsorption and reaction (SILAR) at room temperature onto ZnO nanowires (NWs). The as-deposited CdTe layer exhibits poor crystalline quality and not well defined optical transition which is probably result of its amorphous nature. The implementation of an annealing step and chemical treatment by CdCl{sub 2} to the classical SILAR technique improved significantly the CdTe film quality. The XRD analysis showed that the as treated layers are crystallized in the cubic zinc blende structure. The full coverage of ZnO nanowires and thickness of the CdTe shell, composed of small crystallites, was confirmed by STEM and TEM analysis. The layer thickness could be controlled by the number of SILAR cycles. The sharper optical transitions for the annealed and CdCl{sub 2} treated heterostructures additionally proves the enhancement of the layer crystalline quality. For comparison CdTe was also deposited by close space sublimation (CSS) method onto ZnO nanowires. It is shown that the SILAR deposited CdTe exhibits equal crystalline and optical properties to that prepared by CSS. These results demonstrate that SILAR technique is more suitable for conformal thin film deposition on nanostructures. CdTe extremely thin film deposited by SILAR method onto ZnO nanowire. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

CdTe deposition by successive ionic layer adsorption and reaction (SILAR) technique onto ZnO nanowires

International Nuclear Information System (INIS)

Salazar, Raul; Delamoreanu, Alexandru; Saidi, Bilel; Ivanova, Valentina; Levy-Clement, Claude

2014-01-01

In this study is reported CdTe deposition by Successive Ionic Layer Adsorption and reaction (SILAR) at room temperature onto ZnO nanowires (NWs). The as-deposited CdTe layer exhibits poor crystalline quality and not well defined optical transition which is probably result of its amorphous nature. The implementation of an annealing step and chemical treatment by CdCl 2 to the classical SILAR technique improved significantly the CdTe film quality. The XRD analysis showed that the as treated layers are crystallized in the cubic zinc blende structure. The full coverage of ZnO nanowires and thickness of the CdTe shell, composed of small crystallites, was confirmed by STEM and TEM analysis. The layer thickness could be controlled by the number of SILAR cycles. The sharper optical transitions for the annealed and CdCl 2 treated heterostructures additionally proves the enhancement of the layer crystalline quality. For comparison CdTe was also deposited by close space sublimation (CSS) method onto ZnO nanowires. It is shown that the SILAR deposited CdTe exhibits equal crystalline and optical properties to that prepared by CSS. These results demonstrate that SILAR technique is more suitable for conformal thin film deposition on nanostructures. CdTe extremely thin film deposited by SILAR method onto ZnO nanowire. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Effect of gamma irradiation on the structural and magnetic properties of Co–Zn spinel ferrite nanoparticles

International Nuclear Information System (INIS)

Raut, Anil V.; Kurmude, D.V.; Shengule, D.R.; Jadhav, K.M.

2015-01-01

Highlights: • Co–Zn ferrite nanoparticles were examined before and after γ-irradiation. • Single phase cubic spinel structure of Co–Zn was confirmed by XRD data. • The grain size was reported in the range of 52–62 nm after γ-irradiation. • Ms, Hc, n B were reported to be increased after gamma irradiation. - Abstract: In this work, the structural and magnetic properties of Co 1−x Zn x Fe 2 O 4 (0.0 ≤ x ≤ 1.0) ferrite nanoparticles were studied before and after gamma irradiation. The as-synthesized samples of Co–Zn ferrite nanoparticles prepared by sol–gel auto-combustion technique were analysed by XRD which suggested the single phase; cubic spinel structure of the material. Crystal defects produced in the spinel lattice were studied before and after Co 60 γ-irradiation in a gamma cell with a dose rate of 0.1 Mrad/h in order to report the changes in structural and magnetic properties of the Co–Zn ferrite nanoparticles. The average crystallite size (t), lattice parameter (α) and other structural parameters of gamma-irradiated and un-irradiated Co 1−x Zn x Fe 2 O 4 spinel ferrite system was calculated from XRD data. The morphological characterizations were performed using scanning electron microscopy (SEM). The magnetic properties were measured using pulse field hysteresis loop tracer by applying magnetic field of 1000 Oe, and the analysis of data obtained revealed that the magnetic property such as saturation magnetization (Ms), coecivity (Hc), magneton number (n B ) etc. magnetic parameters were increased after irradiation

Effects of co-dopants on the magnetic properties of Ni–Zn ferrites

Energy Technology Data Exchange (ETDEWEB)

Wang, Sea-Fue, E-mail: sfwang@ntut.edu.tw; Hsu, Yung-Fu; Chou, Kai-Mou; Tsai, Jeng-Ting

2015-01-15

In this study, substitution of co-dopants into the Ni{sub 0.4}Zn{sub 0.6}Fe{sub 2}O{sub 4} ceramic was performed. Al{sup 3+}, Sn{sup 4+} and Ti{sup 4+} ions were added to the Ni{sub 0.4}Zn{sub 0.4}Li{sub 0.10}Fe{sub 2.10}O{sub 4} ceramic to improve magnetic properties. After sintering, all samples were indexed on a spinel structure and no detectable second phase was observed. When the concentration of dopants increased, the grain size of the Ni–Zn ferrites increased from 1.40 to 6.05 μm and the saturation magnetization declined from 428.8 emu/cm{sup 3} to 374.0 emu/cm{sup 3}. Amongst the systems investigated, the Ni{sub 0.4}Zn{sub 0.4}Li{sub 0.10}Al{sub 0.050}Fe{sub 2.050}O{sub 4}, Ni{sub 0.4}Zn{sub 0.425}Li{sub 0.10}Ti{sub 0.025}Fe{sub 2.050}O{sub 4}, and Ni{sub 0.4}Zn{sub 0.450}Li{sub 0.10}Ti{sub 0.050}Fe{sub 2.000}O{sub 4} ceramics revealed promising magnetic properties for applications. The measured initial permeability and quality factor were respectively 291.9 and 45.1 for the Ni{sub 0.4}Zn{sub 0.4}Li{sub 0.10}Al{sub 0.050}Fe{sub 2.050}O{sub 4} ceramic, 316.9 and 42.5 for the Ni{sub 0.4}Zn{sub 0.425}Li{sub 0.10}Ti{sub 0.025}Fe{sub 2.050}O{sub 4} ceramic, 429.4 and 34.8 for the Ni{sub 0.4}Zn{sub 0.450}Li{sub 0.10}Ti{sub 0.050}Fe{sub 2.000}O{sub 4} ceramic. The high initial permeability and quality factor values associated with good electrical resistivity (>10{sup 6} Ω-cm) qualify the ceramics for high frequency applications. - Highlights: • Co-dopants Al{sup 3+}–Li{sup +}, Sn{sup 4+}–Li{sup +}, and Ti{sup 4}–Li{sup +} were substituted into Ni–Zn lattices. • Grain size of Ni–Zn ferrites grew from 1.40 to 6.05 μm with rising dopants content. • Saturation magnetization declined from 428.8 to 374.0 emu/cm{sup 3} with adding dopants. • Ni{sub 0.4}Zn{sub 0.4}Li{sub 0.10}Al{sub 0.050}Fe{sub 2.050}O{sub 4} ceramic showed an μ{sub i} of 291.9 and a Q{sub f} of 45.1.

Magnetism in V-/Mn-doped ZnO layers fabricated on sapphire

Energy Technology Data Exchange (ETDEWEB)

Mofor, A.C.; El-Shaer, A.; Schlenker, E.; Bakin, A.; Waag, A. [Technical University Braunschweig, Institute of Semiconductor Technology, Braunschweig (Germany); Reuss, F.; Kling, R.; Schoch, W.; Limmer, W. [University Ulm, Department of Semiconductor Physics, Ulm (Germany); Ahlers, H.; Siegner, U.; Sievers, S.; Albrecht, M. [Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany); Eisenmenger, J.; Mueller, T.; Ziemann, P. [University Ulm, Department of Solid State Physics, Ulm (Germany); Huebel, A.; Denninger, G. [Universitaet Stuttgart, 2. Physkalisches Institut, Stuttgart (Germany)

2007-07-15

Doping ZnO with transition metals (TM) is an obvious approach to produce diluted magnetic semiconductors for magnetoelectronic and spintronic applications. We have carried out experimental studies on the fabrication and characterisation of Mn-doped ZnO layers and V-doped ZnO layers and nanorods, the results of which are reviewed in this paper. From SQUID measurements, both epitaxial and implanted ZnMnO layers show paramagnetic behaviour. Epitaxial ZnVO layers show ferromagnetic SQUID signals, but the presence of any secondary phases in the ZnVO layers may not be ruled out. We also show that the used Al{sub 2}O{sub 3} substrates produce a ferromagnetic SQUID signal, that complicates the analysis of magnetisation data and hence the confirmation of ferromagnetism only from SQUID results. (orig.)

Microstructural evaluation and magnetic Ni-Zn ferrite sintered by microwave energy

International Nuclear Information System (INIS)

Diniz, Veronica Cristhina S.; Vieira, Debora A.; Costa, Ana Cristina F.M.; Kiminami, R.H.G.A.; Cornejo, Daniel Reinaldo

2011-01-01

The present Ni-Zn ferrite magnetic properties sensitive to microstructure and obtain a ferrite with a uniform microstructure is the biggest challenge in the advancement of new technologies. This study proposes to evaluate the microstructure and magnetic properties of Ni-Zn ferrite sintered by microwave energy. The samples were previously synthesized by combustion reaction using urea and glycine, with 1200 deg C/2h sintered at a heating rate of 5 deg C/min, and characterized by density, XRD, SEM and magnetic measurements. The results show that the sample synthesized with glycine showed the formation of ferrite phase and traces of secondary phase hematite, grains with undefined format, and a high porosity and inter intragranular. The sample synthesized with urea gave only the ferrite phase, with hexagonal grains, and low intergranular porosity. The sample synthesized with urea showed better magnetic characteristics when compared with the samples synthesized with glycine. (author)

Iron-based soft magnetic composites with Mn-Zn ferrite nanoparticles coating obtained by sol-gel method

Science.gov (United States)

Wu, Shen; Sun, Aizhi; Xu, Wenhuan; Zhang, Qian; Zhai, Fuqiang; Logan, Philip; Volinsky, Alex A.

2012-11-01

This paper focuses on iron-based soft magnetic composites which were synthesized by utilizing Mn-Zn ferrite nanoparticles to coat iron powder. The nanocrystalline iron powders, with an average particle diameter of 20 nm, were obtained via the sol-gel method. Scanning electron microscopy, energy dispersive X-ray spectroscopy and distribution maps show that the iron particle surface is covered with a thin layer of Mn-Zn ferrites. Mn-Zn ferrite uniformly coated the surface of the powder particles, resulting in a reduced imaginary permeability, increased electrical resistivity and a higher operating frequency of the synthesized magnets. Mn-Zn ferrite coated samples have higher permeability and lower magnetic loss when compared with the non-magnetic epoxy resin coated compacts. The real part of permeability increases by 33.5% when compared with the epoxy resin coated samples at 10 kHz. The effects of heat treatment temperature on crystalline phase formation and on the magnetic properties of the Mn-Zn ferrite were investigated via X-ray diffraction and a vibrating sample magnetometer. Ferrites decomposed to FeO and MnO after annealing above 400 °C in nitrogen; thus it is the optimum annealing temperature to attain the desired permeability.

Formaldehyde sensor based on Ni-doped tetrapod-shaped ZnO nanopowder induced by external magnetic field

Science.gov (United States)

Bai, Zikui; Xie, Changsheng; Hu, Mulin; Zhang, Shunping

2008-12-01

The sensors based on Ni-doped ZnO nanopowder with tetrapod-shape (T-ZnO) were fabricated by screen-printing technique with external magnetic field in different direction. The morphologies and crystal structures of the thick film were characterized by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM), respectively. Gas-sensing property of sensors responded to 100 ppm formaldehyde was also detected. The results show that the direction of magnetic field has crucial effect on the sensor sensitivity. The sensors based on 5 wt% Ni-doped T-ZnO induced by magnetic field in parallel direction to the thick film surface, has the optimization sensitivity, the shortest response and recovery time, which are 10.6, 16 and 15 s, respectively. The magnetic-field induction model and the gas-sensing mechanism of the Ni-doped T-ZnO are proposed.

Revisiting magnetism of capped Au and ZnO nanoparticles: Surface band structure and atomic orbital with giant magnetic moment

Energy Technology Data Exchange (ETDEWEB)

Hernando, Antonio; Crespo, Patricia [Instituto de Magnetismo Aplicado, UCM-CSIC-ADIF, Las Rozas. P.O. Box 155, 28230 Madrid (Spain); Dept. Fisica de Materiales, Universidad Complutense, Madrid (Spain); Garcia, Miguel Angel [Instituto de Ceramica y Vidrio, CSIC, C/ Kelsen, 5, Madrid 28049 (Spain); Coey, Michael [Trinity College Dublin, Dublin (Ireland); Ayuela, Andres; Echenique, Pedro Miguel [Centro de Fisica de Materiales, CFM-MPC CSIC-UPV/EHU, Donostia International Physics Center (DIPC), 20018 San Sebastian (Spain); Departamento de Fisica de Materiales, Fac. de Quimicas, Universidad del Pais Vasco UPV-EHU, 20018 San Sebastian (Spain)

2011-10-15

In this article we review the exotic magnetism of nanoparticles (NPs) formed by substances that are not magnetic in bulk as described with generality in Section 1. In particular, the intrinsic character of the magnetism observed on capped Au and ZnO NPs is analysed. X-ray magnetic circular dichroism (XMCD) analysis has shown that the magnetic moments are intrinsic and lie in the Au and Zn atoms, respectively, as analysed in Section 2, where the general theoretical ideas are also revisited. Since impurity atoms bonded to the surface act as donor or acceptor of electrons that occupy the surface states, the anomalous magnetic response is analysed in terms of the surface band in Section 3. Finally, Section 4 summarizes our last theoretical proposal. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Tribochemistry of Ionic Liquid Lubricant on Magnetic Media

Directory of Open Access Journals (Sweden)

Hirofumi Kondo

2012-01-01

Full Text Available The newly synthesized perfluoropolyether (PFPE ionic liquid whose terminal group is an ammonium salt with a carboxylic acid has better frictional properties when compared to the conventional PFPEs. Stick-slip motion was not observed even for the smooth surface for the modified PFPE tape. The friction is almost independent of the PFPE structure, but depends on the amine structures. The ammonium salt being tightly anchored to the rubbing surface covers uniformly, which leads to better lubricity. The higher dispersive interaction of the hydrophobic group of the amine is endowed with a compensating friction reduction. Steric hindrance of the hydrophilic group causes a high friction. Based on these findings, a saturated long chain ammonium salt is the best selection. Moreover, the modified PFPEs are dissolved in alcohol and hexane, which makes practical use convenient without any environmental problems. These ionic lubricants invented around 1987 have been used for magnetic tapes for about a quarter century because of their good lubricity and are reviewed in this paper.

A solid-state dye-sensitized solar cell based on a novel ionic liquid gel and ZnO nanoparticles on a flexible polymer substrate

Energy Technology Data Exchange (ETDEWEB)

Wei Di; Ryhanen, Tapani [Nokia Research Centre c/o Nanoscience Centre, University of Cambridge, 11 JJ Thomson Avenue, CB3 0FF, Cambridge (United Kingdom); Unalan, Husnu Emrah; Amaratunga, Gehan [Centre of Advanced Photonics and Electronics, Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, CB3 0FA, Cambridge (United Kingdom); Han Dongxue; Zhang Qixian; Niu Li [Changchun Institute of Applied Chemistry, Chinese Academy of Science, 130000 Changchun (China)], E-mail: di.wei@nokia.com

2008-10-22

This paper describes a new strategy to make a full solid-state, flexible, dye-sensitized solar cell (DSSC) based on novel ionic liquid gel, organic dye, ZnO nanoparticles and carbon nanotube (CNT) thin film stamped onto a polyethylene terephthalate (PET) substrate. The CNTs serve both as the charge collector and as scaffolds for the growth of ZnO nanoparticles, where the black dye molecules are anchored. It opens up the possibility of developing a continuous roll to roll processing for THE mass production of DSSCs.

Magnetization of correlated electron systems. MnSi thin films, CrB2 single crystals and two-dimensional electron systems in MgZnO/ZnO

International Nuclear Information System (INIS)

Brasse, Matthias

2014-01-01

Torque magnetometry at low temperature is performed to investigate the magnetic properties of MnSi thin films, of a CrB 2 single crystal and of a two-dimensional electron system (2DESs) formed at the interface of MgZnO/ZnO. The magnetic anisotropy and phase diagram of MnSi as well as information on the electronic structure of CrB 2 are obtained. The MgZnO/ZnO 2DESs exhibits the de Haas-van Alphen effect and non-equilibrium currents which are analyzed in order to determine ground state properties and excited states, respectively.

Resonantly enhanced spin-lattice relaxation of Mn2 + ions in diluted magnetic (Zn,Mn)Se/(Zn,Be)Se quantum wells

Science.gov (United States)

Debus, J.; Ivanov, V. Yu.; Ryabchenko, S. M.; Yakovlev, D. R.; Maksimov, A. A.; Semenov, Yu. G.; Braukmann, D.; Rautert, J.; Löw, U.; Godlewski, M.; Waag, A.; Bayer, M.

2016-05-01

The dynamics of spin-lattice relaxation in the magnetic Mn2 + ion system of (Zn,Mn)Se/(Zn,Be)Se quantum-well structures are studied using optical methods. Pronounced cusps are found in the giant Zeeman shift of the quantum-well exciton photoluminescence at specific magnetic fields below 10 T, when the Mn spin system is heated by photogenerated carriers. The spin-lattice relaxation time of the Mn ions is resonantly accelerated at the cusp magnetic fields. Our theoretical analysis demonstrates that a cusp occurs at a spin-level mixing of single Mn2 + ions and a quick-relaxing cluster of nearest-neighbor Mn ions, which can be described as intrinsic cross-relaxation resonance within the Mn spin system.

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

Energy Technology Data Exchange (ETDEWEB)

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

2017-04-01

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

Effect of Cu-Dopant on the Structural, Magnetic and Electrical Properties of ZnO

Science.gov (United States)

Aryanto, D.; Kurniawan, C.; Subhan, A.; Sudiro, T.; Sebayang, P.; Ginting, M.; Siregar, S. M. K.; Nasruddin, M. N.

2017-05-01

Zn1- x Cu x O (x = 0, 2, 3, and 4 at.%) was synthesized by using solid-state reaction technique. The ZnO and CuO powders were mixed and then milled by using high-speed shaker mill. The influence of Cu dopants on the structure, magnetic, and electrical properties was investigated by using XRD, VSM, and I-V and C-V measurements. The XRD analysis showed that the Zn1- x Cu x O had hexagonal wurtzite polycrystalline. The diffraction intensity decreased and the peak position shifted directly to a higher 2θ angle with increasing the dopant concentration. Furthermore, the lattice parameters decreased when the ZnO was doped with x = 0.04, which indicated that the crystal structure changed. The increase of Cu dopants was believed to affect the magnetic and electrical properties of ZnO.

Optical and Magnetic Properties of Fe Doped ZnO Nanoparticles Obtained by Hydrothermal Synthesis

Directory of Open Access Journals (Sweden)

Xiaojuan Wu

2014-01-01

Full Text Available Diluted magnetic semiconductors Zn1-xFexO nanoparticles with different doping concentration (x=0, 0.01, 0.05, 0.10, and 0.20 were successfully synthesized by hydrothermal method. The crystal structure, morphology, and optical and magnetic properties of the samples were characterized by X-ray diffraction (XRD, energy dispersive spectrometer (EDS, high-resolution transmission electron microscopy (HRTEM, Raman scattering spectra (Raman, photoluminescence spectra (PL, and the vibrating sample magnetometer (VSM. The experiment results show that all samples synthesized by this method possess hexagonal wurtzite crystal structure with good crystallization, no other impurity phases are observed, and the morphology of the sample shows the presence of ellipsoidal nanoparticles. All the Fe3+ successfully substituted for the lattice site of Zn2+ and generates single-phase Zn1-xFexO. Raman spectra shows that the peak shifts to higher frequency. PL spectra exhibit a slight blue shift and the UV emission is annihilated with the increase of Fe3+ concentration. Magnetic measurements indicated that Fe-doped ZnO samples exhibit ferromagnetic behavior at room temperature and the saturation magnetization is enhanced with the increase of iron doping content.

Effect of gamma irradiation on the structural and magnetic properties of Co–Zn spinel ferrite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Raut, Anil V., E-mail: nano9993@gmail.com [Vivekanand Arts, Sardar Dalipsingh Commerce and Science College, Aurangabad 431004, (M.S.) India (India); Kurmude, D.V. [Milind College of Science, Aurangabad 431004, (M.S.) India (India); Shengule, D.R. [Vivekanand Arts, Sardar Dalipsingh Commerce and Science College, Aurangabad 431004, (M.S.) India (India); Jadhav, K.M. [Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004, (M.S.) India (India)

2015-03-15

Highlights: • Co–Zn ferrite nanoparticles were examined before and after γ-irradiation. • Single phase cubic spinel structure of Co–Zn was confirmed by XRD data. • The grain size was reported in the range of 52–62 nm after γ-irradiation. • Ms, Hc, n{sub B} were reported to be increased after gamma irradiation. - Abstract: In this work, the structural and magnetic properties of Co{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} (0.0 ≤ x ≤ 1.0) ferrite nanoparticles were studied before and after gamma irradiation. The as-synthesized samples of Co–Zn ferrite nanoparticles prepared by sol–gel auto-combustion technique were analysed by XRD which suggested the single phase; cubic spinel structure of the material. Crystal defects produced in the spinel lattice were studied before and after Co{sup 60} γ-irradiation in a gamma cell with a dose rate of 0.1 Mrad/h in order to report the changes in structural and magnetic properties of the Co–Zn ferrite nanoparticles. The average crystallite size (t), lattice parameter (α) and other structural parameters of gamma-irradiated and un-irradiated Co{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} spinel ferrite system was calculated from XRD data. The morphological characterizations were performed using scanning electron microscopy (SEM). The magnetic properties were measured using pulse field hysteresis loop tracer by applying magnetic field of 1000 Oe, and the analysis of data obtained revealed that the magnetic property such as saturation magnetization (Ms), coecivity (Hc), magneton number (n{sub B}) etc. magnetic parameters were increased after irradiation.

Enhanced magnetic properties in ZnCoAlO caused by exchange-coupling to Co nanoparticles

International Nuclear Information System (INIS)

Feng, Qi; Dizayee, Wala; Li, Xiaoli; Score, David S; Neal, James R; Behan, Anthony J; Mokhtari, Abbas; Alshammari, Marzook S; Al-Qahtani, Mohammed S; Blythe, Harry J; Fox, A Mark; Gehring, Gillian A; Chantrell, Roy W; Heald, Steve M; Xu, Xiao-Hong

2016-01-01

We report the results of a sequence of magnetisation and magneto-optical studies on laser ablated thin films of ZnCoAlO and ZnCoO that contain a small amount of metallic cobalt. The results are compared to those expected when all the magnetization is due to isolated metallic clusters of cobalt and with an oxide sample that is almost free from metallic inclusions. Using a variety of direct magnetic measurements and also magnetic circular dichroism we find that there is ferromagnetism within both the oxide and the metallic inclusions, and furthermore that these magnetic components are exchange-coupled when aluminium is included. This enhances both the coercive field and the remanence. Hence the presence of a controlled quantity of metallic nanoparticles in ZnAlO can improve the magnetic response of the oxide, thus giving great advantages for applications in spintronics. (paper)

Magnetic and photocatalytic properties of nanocrystalline ZnMn2 O4

Indian Academy of Sciences (India)

Decomposition of oxalate precursors at low temperature (∼ 450°C) yielded phase pure ZnMn2O4 nanoparticles. The size of the nanoparticles of ZnMn2O4 obtained from reverse micellar method is relatively much smaller (20–30 nm) as compared to those made by the co-precipitation (40–50 nm) method. Magnetic studies ...

Evaluation of magnetic properties of NI-ZN ferrites obtained by different synthesis methods

International Nuclear Information System (INIS)

Simoes, A.N.; Neiva, L.S.; Simoes, V.N.; Gama, L.; Gomes Filho, A.C.; Oliveira, J.B.L.

2012-01-01

Ceramic oxides that exhibit ferromagnetic behavior represent important commercial products for the electronics industry and are commonly known as ferrites. The Ni-Zn ferrites are considered to be one of the most versatile and soft due to its high electrical resistivity and low eddy current losses. Thus, this study aims to evaluate the magnetic properties of Ni-Zn ferrite obtained by the Pechini and combustion reaction. After synthesis the powders were characterized by XRD, SEM, BET and magnetic measurements. The results showed that for both methods of synthesis used was the formation of the spinel phase of Ni-Zn ferrite. The micrographs show that the powders obtained by both methods have regular shapes and spherical. Were determined by BET surface area is 26 m 2 /g by the Pechini and 13 m 2 /g by combustion. And the samples synthesized by Pechini method obtained the best magnetic characteristics (author)

Synthesis and characterization of ionic liquid immobilized on magnetic nanoparticles: A recyclable heterogeneous organocatalyst for the acetylation of alcohols

Science.gov (United States)

Ghorbani-Choghamarani, Arash; Norouzi, Masoomeh

2016-03-01

Herein, we describe a simple and efficient procedure for the preparation of 3-((3-(trisilyloxy)propyl)propionamide)-1-methylimidazolium chloride ionic liquid supported on magnetic nanoparticle (TPPA-IL-Fe3O4). The structure of this magnetic ionic liquid is fully characterized by FT-IR, TGA, XRD, VSM, SEM, EDX and DLS techniques. TPPA-IL-Fe3O4 is employed as a catalyst for the acetylation of alcohols with acetic anhydride under mild and heterogeneous conditions at room temperature with good to excellent yields. The magnetic catalyst could be readily separate from the reaction media by simple magnetic decantation, and reused several times without significant loss of its catalytic activity.

Structural and magnetic investigation of dilute magnetic semiconductors based on GaN and ZnO

Energy Technology Data Exchange (ETDEWEB)

Kammermeier, Tom

2010-01-19

The two wide band gap dilute magnetic semiconductors (DMS) Gd:GaN and Co:ZnO are among the most favored materials for spintronic applications. Despite intense research efforts during the last years, the origin of the magnetic order is still under debate. This work reports structural and magnetic investigations on these DMS materials employing several complementary techniques. The X-ray linear dichroism (XLD) has been used to gain element-specific insight into the local structure of dopants and cations. X-ray diffraction (XRD) was used to probe the global structural properties. Magnetic characterization by superconducting quantum interference device (SQUID) has been complemented by electron spin resonance (ESR) and X-ray magnetic circular dichroism (XMCD). Gd:GaN samples were fabricated by focused-ion-beam (FIB) implantation and molecular beam epitaxy (MBE). Room temperature ferromagnetic-like behavior as found for some of our samples by SQUID could not be reliably reproduced. Instead XMCD measurements at the Gd L{sub 3}-edge reveal paramagnetic behavior of the dopant. Additionally a possible magnetic polarization of Ga atoms of the host crystal is shown to be too small to explain the total magnetization of these samples. In some samples the formation of Gd and GdN clusters was evidenced by ESR measurements but it can only account for low temperature ferromagnetic-like behavior. Intrinsic room temperature ferromagnetism of this material as seen by SQUID cannot be confirmed by any other technique - neither ESR nor XMCD. Co:ZnO samples used for this work were predominantly grown by reactive magnetron sputtering (RMS). As shown by XLD analysis, 95% of the Co atoms are incorporated on substitutional Zn-sites in samples of best structural quality. These samples consistently show paramagnetic behavior as found by SQUID, XMCD and ESR. RMS growth of Co:ZnO with reduced oxygen partial pressure yields a magnetic behavior known from ferromagnetic nanoclusters. The X

X-ray and magnetic studies of Zn substituted Ni–Pb ferrites

Indian Academy of Sciences (India)

Unknown

nic applications such as transformers, choke coils, noise filters, recording heads etc. Nickel ferrites and Zn2+ sub- stituted nickel-ferrites are widely used in electronics and electrical industries as they exhibit interesting variations in the electrical and magnetic properties. Electrical and magnetic properties are influenced by ...

Synthesis, Magnetization, and Electrical Transport Properties of Mn3Zn0.9Cu0.1N

Directory of Open Access Journals (Sweden)

Y. Yin

2013-01-01

Full Text Available We synthesized Mn3Zn0.9Cu0.1N by solid state reaction, and magnetic as well as electrical transport properties were investigated. It is found that Mn3Zn0.9Cu0.1N exhibits a first-order antiferromagnetism (AFM to paramagnetic (PM transition with the Néel temperature TN ~163 K, and substitution of Cu for Zn would favor ferromagnetism (FM state and weaken AFM ground state, leading to a convex curvature character of M(T curve. With high external fields 10 kOe–50 kOe, magnetic transition remains a robust AFM-PM feature while FM phase is completely suppressed. Thermal hysteresis of M(T under 500 Oe is also suppressed when the magnetic field exceeds 10 kOe. Mn3Zn0.9Cu0.1N exhibits a good metallic behavior except for a slope change around TN, which is closely related to AFM-PM magnetic transition. Compared with the first differential of resistivity with respect to temperature for (dρ/dTMn3ZnN in transition temperature range, the absolute value of (dρ/dTMn3Zn0.9Cu0.1N is much lower which is close to zero.

Ionic magnetic fluids in polar solvents with tuned counter-ions

Energy Technology Data Exchange (ETDEWEB)

Lopes Filomeno, C. [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Lab. PHENIX, Paris (France); Grupo de Fluidos Complexos Inst. de Quimica, Univ. de Brasília, Brasília (DF) (Brazil); Kouyaté, M. [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Lab. PHENIX, Paris (France); Cousin, F. [Lab. Léon Brillouin – CE-Saclay, Gif-sur-Yvette (France); Demouchy, G. [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Lab. PHENIX, Paris (France); Dpt de physique, Univ. de Cergy Pontoise, Cergy-Pontoise (France); Dubois, E.; Michot, L.; Mériguet, G. [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Lab. PHENIX, Paris (France); Perzynski, R., E-mail: regine.perzynski@upmc.fr [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Lab. PHENIX, Paris (France); Peyre, V.; Sirieix-Plénet, J. [Sorbonne Universités, UPMC Univ Paris 06, CNRS, Lab. PHENIX, Paris (France); Tourinho, F.A. [Grupo de Fluidos Complexos Inst. de Quimica, Univ. de Brasília, Brasília (DF) (Brazil)

2017-06-01

The aim of the present study is to propose a new reproducible method for preparing colloidal dispersions of electrostatically charged nanoparticles (NPs) in polar solvents with different kinds of counter-ions. Maghemite NPs are here dispersed in solvents of different dielectric constant, namely water, dimethylsulfoxide (DMSO) and an ionic liquid, ethylammonium nitrate (EAN). If the existence of a NP superficial charge happens to be necessary for the colloidal stability of the dispersions in these three solvents, the standard DLVO theory cannot be used any more to describe the colloidal stability in EAN. The structure of the dispersions and the strength of the interparticle repulsion are investigated by small angle X-ray scattering measurements, in association with Ludwig–Soret coefficient determinations. Specificities, associated to the nature of the counter-ions are identified in this work on the colloidal stability, on the interparticle repulsion and on the Ludwig–Soret coefficient. - Highlights: • A controlled synthesis of ionic magnetic fluids in three polar solvents is proposed. • Colloidal repulsion in the magnetic fluids depends on the counter-ion nature. • Soret coefficient of citrate-coated maghemite nanoparticles is probed in water-pH7. • Thermophilicity of nanoparticles depends on the nature of their counter-ions. • Nanoparticles dressed with same counter-ions have solvent-dependent thermoproperties.

Metal coordination in the high-temperature leaching of roasted NdFeB magnets with the ionic liquid betainium bis(trifluoromethylsulfonyl)imide

OpenAIRE

Orefice, Martina; Binnemans, Koen; Vander Hoogerstraete, Tom

2018-01-01

Ionic liquids are largely used to leach metals from primary (ores) and secondary sources (end-of-life products). However, dry ionic liquids with a carboxylic function on the cation have not yet been used to leach metals at temperature above 100 °C and under atmospheric pressure. The ionic liquid betainium bis(trifluoromethylsulfonyl)imide, [Hbet][Tf2N], was used in the dry state to recover neodymium, dysprosium and cobalt from NdFeB magnets and NdFeB production scrap. The magnets and the scra...

Iron-based soft magnetic composites with Mn–Zn ferrite nanoparticles coating obtained by sol–gel method

International Nuclear Information System (INIS)

Wu, Shen; Sun, Aizhi; Xu, Wenhuan; Zhang, Qian; Zhai, Fuqiang; Logan, Philip; Volinsky, Alex A.

2012-01-01

This paper focuses on iron-based soft magnetic composites which were synthesized by utilizing Mn–Zn ferrite nanoparticles to coat iron powder. The nanocrystalline iron powders, with an average particle diameter of 20 nm, were obtained via the sol–gel method. Scanning electron microscopy, energy dispersive X-ray spectroscopy and distribution maps show that the iron particle surface is covered with a thin layer of Mn–Zn ferrites. Mn–Zn ferrite uniformly coated the surface of the powder particles, resulting in a reduced imaginary permeability, increased electrical resistivity and a higher operating frequency of the synthesized magnets. Mn–Zn ferrite coated samples have higher permeability and lower magnetic loss when compared with the non-magnetic epoxy resin coated compacts. The real part of permeability increases by 33.5% when compared with the epoxy resin coated samples at 10 kHz. The effects of heat treatment temperature on crystalline phase formation and on the magnetic properties of the Mn–Zn ferrite were investigated via X-ray diffraction and a vibrating sample magnetometer. Ferrites decomposed to FeO and MnO after annealing above 400 °C in nitrogen; thus it is the optimum annealing temperature to attain the desired permeability. - Highlights: ► Uniformly coated Mn–Zn ferrite powder increased the operating frequency of SMCs. ► Compared with epoxy coated, the permeability of SMCs increased by 33.5% at 10 kHz. ► 400 °C is the optimum annealing temperature to attain the desired permeability.

Magnetic losses versus sintering treatment in Mn-Zn ferrites

Energy Technology Data Exchange (ETDEWEB)

Beatrice, Cinzia, E-mail: c.beatrice@inrim.it [Istituto Nazionale di Ricerca Metrologica, Nanoscience and Materials Division, Torino (Italy); Tsakaloudi, Vasiliki [Laboratory of Inorganic Materials, CERTH, Thermi-Thessaloniki (Greece); Dobák, Samuel [Institute of Physics, P.J. Šafárik University, Košice (Slovakia); Zaspalis, Vassilios [Department of Chemical Engineering Aristotle University of Thessaloniki, Thessaloniki (Greece); Fiorillo, Fausto [Istituto Nazionale di Ricerca Metrologica, Nanoscience and Materials Division, Torino (Italy)

2017-05-01

Mn-Zn ferrites prepared by different sintering schedules at 1325 °C, 1340 °C, and 1360 °C, have been characterized from the structural, electrical, and magnetic viewpoint. Magnetic losses and complex permeability have been, in particular, measured and analyzed from quasi-static excitation up to 1 GHz. It is observed that lower sintering temperatures and shorter treatment times lead to more homogeneous grain structure and better soft magnetic response at all frequencies. It is shown, however, that, once the contribution by eddy currents is singled out, the energy losses tend to coincide beyond a few MHz in the differently treated samples. The interpretative approach consists in separating the contributions by the domain wall displacements and the magnetization rotations to complex permeability and losses as a function of frequency. This can be accomplished in a relatively simple way in the low induction region described by the Rayleigh law, where these quantities can be quantitatively related and the linear Landau-Lifshitz-Gilbert equation applies, account being taken of the distribution in amplitude and orientation of the local anisotropy fields. - Highlights: • DC-1 GHz magnetic losses and complex permeability of Mn-Zn ferrites are analyzed. • Contributions by domain wall displacements and rotations are separately obtained. • Energy losses caused by eddy currents and spin damping are separately identified. • Microstructure is shown to chiefly affect the domain wall processes. • Rotational permeability and loss are predicted through Landau-Lifshitz equation.

Effects of High-Energy Proton-Beam Irradiation on the Magnetic Properties of ZnO Nanorods

Energy Technology Data Exchange (ETDEWEB)

Park, Jun Kue; Kwon, Hyeok-Jung; Cho, Yong Sub [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-10-15

There are still many problem for the application due to its unstable magnetism state and too small magnetization values. Here we investigate magnetic properties of ZnO nanorods after high-energy proton-beam irradiation. Electron spin resonance (ESR) measurement on temperature was made to identify intrinsic or extrinsic defects as well as to observe magnetic ordering after irradiation. Understanding the effects of proton beam irradiation on magnetic behavior may help to shed light on the mechanism responsible for the magnetic ordering in this material. We have investigated proton-beam irradiation effects on the magnetic properties of ZnO nanorods. After irradiation a broad ESR line is observed, indicating emergence of ferromagnetic ordering up to room temperature. In M-H curve, stronger coercive field is observed after irradiation.

Structural and magnetic properties of Zn{sub X}Co{sub 1−X}Fe{sub 2}O{sub 4} nanoparticles: Nonsaturation of magnetization

Energy Technology Data Exchange (ETDEWEB)

Chithra, M.; Anumol, C.N. [Department of Physics, Central University of Kerala, Riverside Transit Campus, Nileshwar, P.O. Padnekkad, Kasaragod, Kerala 671314 (India); Sahu, Baidyanath [Department of Physics, I.I.T. Bombay, Powai, Mumbai 400076 (India); Sahoo, Subasa C., E-mail: subasa.cs@gmail.com [Department of Physics, Central University of Kerala, Riverside Transit Campus, Nileshwar, P.O. Padnekkad, Kasaragod, Kerala 671314 (India)

2017-02-15

Zn{sub X}Co{sub 1-X}Fe{sub 2}O{sub 4} nanoparticles were synthesized by sol-gel method and were annealed at two different temperatures; 500 °C and 900 °C in air for 2 h. Structural studies were carried out by X-ray diffraction and Fourier transformed infrared spectroscopy. The crystallite size didn’t show any variation with the increase in Zn{sup 2+} concentration and was increased after annealing. The magnetization value at 300 K for the as-prepared samples increased from 53 emu/g to 60 emu/g when Zn{sup 2+} concentration increased from x=0 to 0.2 and then it decreased to 11 emu/g for x=1. Similar magnetic behavior was also observed for the annealed samples with a peak at x=0.2. A very high magnetization value of 116 emu/g at 60 K was observed for the 900 °C annealed sample with x=0.4. The coercivity decreased monotonically with the increase in the Zn{sup 2+} concentration for both the as- prepared and the annealed samples. The magnetization and coercivity values were observed to be enhanced with the decrease in measurement temperature. The nonsaturation behavior of the magnetic hysteresis loops of these nanoparticle samples observed for all compositions and temperatures was studied by the method of approach to saturation by fitting M(H)=M(∞) [1−(H*/H){sup 1/2}] to the high field data of the initial curve from 20 kOe to 30 kOe. It was observed that H* value which is the measure of the nonsaturation increased with the increase in the Zn{sup 2+} concentration. The observed magnetic properties in these nanoparticle samples can be ascribed to the changed cation distribution in the spinel structure and to the decrease of Co{sup 2+} concentration. - Highlights: • Zn{sub X}Co{sub 1−X}Fe{sub 2}O{sub 4} nanoparticles were prepared by sol-gel technique and were annealed. • Crystallite size didn’t show any variation with the increase in Zn{sup 2+} concentration and was increased after annealing. • Magnetic hysteresis loops showed non-saturation behavior

Structural and magnetic properties of Tb implanted ZnO single crystals

International Nuclear Information System (INIS)

Zhou Shengqiang; Potzger, K.; Muecklich, A.; Eichhorn, F.; Helm, M.; Skorupa, W.; Fassbender, J.

2008-01-01

ZnO single crystals have been implanted with Tb ions. For an atomic concentration of 1.5%, annealing at 823 K leads to an increase of the saturation magnetization per implanted Tb ion up to 1.8 μ B at room temperature. Structural investigations revealed no secondary phase formation, but the out-diffusion of Tb. No significant evidence is found for Tb substituting Zn sites either in the as-implanted or annealed samples. However, indications for the existence of a small amount of Tb nanoclusters however have been found using magnetization versus temperature measurements. The ferromagnetic properties disappear completely upon annealing at 1023 K. This behavior is related to the formation of oxide complexes or nanoparticles

Magnetic and optical properties of Mn-doped ZnO vertically aligned nanorods synthesized by hydrothermal technique

Energy Technology Data Exchange (ETDEWEB)

Panda, J.; Sasmal, I.; Nath, T. K., E-mail: tnath@phy.iitkgp.ernet.in, E-mail: tapnath@gmail.com [Department of Physics, Indian Institute Technology Kharagpur, West Bengal, 721302 (India)

2016-03-15

In this paper we have reported the synthesis of high quality vertically aligned undoped and Mn-doped ZnO single crystalline nanorods arrays on Si (100) substrates using two steps process, namely, initial slow seed layer formation followed by solution growth employing wet chemical hydrothermal method. The shapes of the as grown single crystalline nanorods are hexagonal. The diameter and length of the as grown undoped ZnO nanorods varies in the range of 80-150 nm and 1.0 - 1.4 μm, respectively. Along with the lattice parameters of the hexagonal crystal structure, the diameter and length of Mn doped ZnO nanorods are found to increase slightly as compared to the undoped ZnO nanorods. The X-ray photoelectron spectroscopy confirms the presence of Mn atoms in Mn{sup 2+} state in the single crystalline ZnO nanorods. The recorded photoluminescence spectrum contains two emissions peaks having UV exciton emissions along with a green-yellow emission. The green-yellow emissions provide the evidence of singly ionized oxygen vacancies. The magnetic field dependent magnetization measurements [M (H)] and zero field cooled (ZFC) and field cooled (FC) magnetization [M(T)] measurements have been carried out at different isothermal conditions in the temperature range of 5-300 K. The Mn doped ZnO nanorods clearly show room temperature ferromagnetic ordering near room temperature down to 5 K. The observed magnetization may be attributed to the long range ferromagnetic interaction between bound magnetic polarons led by singly charged oxygen vacancies.

Extraction of triazole fungicides in environmental waters utilizing poly (ionic liquid)-functionalized magnetic adsorbent.

Science.gov (United States)

Liu, Cheng; Liao, Yingmin; Huang, Xiaojia

2017-11-17

This work prepared a new poly (ionic liquid)-functionalized magnetic adsorbent (PFMA) for the extraction of triazole fungicides (TFs) in environmental waters prior to determination by high performance liquid chromatography/diode array detection (HPLC-DAD). A polymerizable ionic liquid, 1-methyl-3-allylimidazolium bis(trifluoromethylsulfonyl)imide was employed to copolymerize with divinylbenzene on the surface of modified magnetite to fabricate the PFMA. The morphology, spectroscopic and magnetic properties of the new adsorbent were investigated by different techniques. A series of key parameters that influence the extraction performance including the amount of PFMA, desorption solvent, adsorption and desorption time, sample pH value and ionic strength were optimized in detail. Under the optimum conditions, the prepared PFMA could extract targeted TFs effectively and quickly under the format of magnetic solid-phase extraction (MSPE). Satisfactory linearities were achieved in the range of 0.1-200.0μg/L for triadimenol and 0.05-200.0μg/L for other TFs with good coefficients of determination above 0.99 for all analytes. The limits of detection (S/N=3) and limits of quantification (S/N=10) for TFs were in the range of 0.0050-0.0078μg/L and 0.017-0.026μg/L, respectively. Environmental waters including lake, river and well waters were used to demonstrate the applicability of developed MSPE-HPLC-DAD method, and satisfactory recoveries and repeatability were obtained. Copyright © 2017 Elsevier B.V. All rights reserved.

Magneto-Ionic Control of Interfacial Magnetic Anisotorpy

Science.gov (United States)

Bauer, Uwe; Emori, Satoru; Beach, Geoffrey

2014-03-01

Voltage control of magnetism could bring about revolutionary new spintronic memory and logic devices. Here, we examine domain wall (DW) dynamics in ultrathin Co films and nanowires under the influence of a voltage applied across a gadolinium oxide gate dielectric that simultaneously acts as an oxygen ion conductor. We investigate two electrode configurations, one with a continuous gate dielectric and the other with a patterned gate dielectric which exhibits an open oxide edge right underneath the electrode perimeter. We demonstrate that the open oxide edge acts as a fast diffusion path for oxygen ions and allows voltage-induced switching of magnetic anisotropy at the nanoscale by modulating interfacial chemistry rather than charge density. At room temperature this effect is limited to the vicinity of the open oxide edge, but at a temperature of 100°C it allows complete control over magnetic anisotropy across the whole electrode area, due to higher oxygen ion mobility at elevated temperature. We then harness this novel ``magneto-ionic'' effect to create unprecedentedly strong voltage-induced anisotropy modifications of 3000 fJ/Vm and create electrically programmable DW traps with pinning strengths of 650 Oe, enough to bring to a standstill DWs travelling at speeds of at least 20 m/s. This work is supported by the National Science Foundation through grant ECCS-1128439.

Synthesis of Cu and Ce co-doped ZnO nanoparticles: crystallographic, optical, molecular, morphological and magnetic studies

Directory of Open Access Journals (Sweden)

Rawat Mohit

2017-07-01

Full Text Available In the present research work, crystallographic, optical, molecular, morphological and magnetic properties of Zn1-xCuxO (ZnCu and Zn1-x-yCeyCuxO (ZnCeCu nanoparticles have been investigated. Polyvinyl alcohol (PVA coated ZnCu and ZnCeCu nanoparticles have been synthesized by chemical sol-gel method and thoroughly studied using various characterization techniques. X-ray diffraction pattern indicates the wurtzite structure of the synthesized ZnCu and ZnCeCu particles. Transmission electron microscopy analysis shows that the synthesized ZnCu and ZnCeCu particles are of spherical shape, having average sizes of 27 nm and 23 nm, respectively. The incorporation of Cu and Ce in the ZnO lattice has been confirmed through Fourier transform infrared spectroscopy. Room temperature photoluminescence spectra of the ZnO doped with Cu and co-doped Ce display two emission bands, predominant ultra-violet near-band edge emission at 409.9 nm (3 eV and a weak green-yellow emission at 432.65 nm (2.27 eV. Room temperature magnetic study confirms the diamagnetic behavior of ZnCu and ferromagnetic behavior of ZnCeCu.

Stabilization mechanism for the polar ZnO(0001̅)-O surface

DEFF Research Database (Denmark)

Wahl, Roman; Lauritsen, Jeppe Vang; Besenbacher, Flemming

2013-01-01

When wurtzite ZnO is sliced perpendicular to the (0001) axis, two different polar surfaces, the (0001)-Zn and (0001̅ )-O terminated surfaces, are formed. In a simple ionic picture, both surfaces are electrostatically unstable due to a diverging electrostatic energy. Although the ionic picture...

Impacts of MnZn doping on the structural and magnetic properties of M-type SrCaLa hexaferrites

Energy Technology Data Exchange (ETDEWEB)

Yang, Yujie; Shao, Juxiang; Wang, Fanhou; Huang, Duohui [Yibin University, Computational Physics Key Laboratory of Sichuan Province, School of Physics and Electronic Engineering, Yibin (China); Liu, Xiansong [Anhui University, Engineering Technology Research Center of Magnetic Materials, Anhui Province, School of Physics and Materials Science, Hefei (China)

2017-05-15

M-type hexaferrites with chemical compositions of Sr{sub 0.5}Ca{sub 0.2}La{sub 0.3}Fe{sub 12.0-2x} (MnZn){sub x} O{sub 19} (0.0 ≤ x ≤ 0.5) were synthesized by the traditional ceramic method. The crystal structure of M-type hexaferrite samples was examined by X-ray diffraction. The structural analyses reveal that all samples are in single M-type hexagonal phase and no secondary phase is present. A physical property measurement system-vibrating sample magnetometer was used to measure the magnetic properties of M-type hexaferrite samples. The saturation magnetization (M{sub s}), remanent magnetization (M{sub r}) and coercivity (H{sub c}) were calculated from magnetic hysteresis loops. M{sub s} first increases with MnZn content (x) from 0.0 to 0.1, and then decreases with MnZn content (x) from 0.1 to 0.5. While, M{sub r} decreases with MnZn content (x) from 0.0 to 0.2, and then increases with MnZn content (x) from 0.2 to 0.5. H{sub c} first decreases with MnZn content (x) from 0.0 to 0.2, and then increase with MnZn content (x) from 0.2 to 0.5. (orig.)

Microstructure and magnetic properties of Co-doped ZnO films deposited by gas flow sputtering

Energy Technology Data Exchange (ETDEWEB)

Sakuma, H., E-mail: hsakuma@cc.utsunomiya-u.ac.jp [Research Division of Functional Materials Design, Utsunomiya University, 7-1-2 Yoto, Utsunomiya 321-8585 (Japan); Watanabe, Y. [Research Division of Functional Materials Design, Utsunomiya University, 7-1-2 Yoto, Utsunomiya 321-8585 (Japan); Aramaki, K.; Yun, K.S. [Sony Chemical and Information Device Corporation, 1078 Kamiishikawa, Kanuma 322-8503 (Japan); Ishii, K. [Research Division of Functional Materials Design, Utsunomiya University, 7-1-2 Yoto, Utsunomiya 321-8585 (Japan); Ikeda, Y.; Kondo, H. [Sony Chemical and Information Device Corporation, 1078 Kamiishikawa, Kanuma 322-8503 (Japan)

2010-10-15

Co-doped ZnO films with a Co concentration of 8-20 at.% were fabricated using the low-energy process of gas flow sputtering. X-ray diffraction, X-ray photoelectron spectroscopy, and optical absorption measurements revealed that the Co ions replace Zn ions in the ZnO matrix and that the Co ions have an oxidation state of 2+. The magnetic properties of the film depend on the Co concentration. The plots of magnetization and inverse susceptibility vs. temperature indicate that the film with a high Co concentration (20 at.%) contains a ferromagnetic component, while that with a low Co concentration (8 at.%) contains an antiferromagnetic component. The film with an intermediate Co concentration (10 at.%) contains a ferromagnetic component with a low Curie temperature. Hysteresis was not found in magnetization curves for all the samples, including the sample at 5 K. The films exhibited a high resistivity of 4 x 10{sup 7}-2 x 10{sup 8} {Omega} cm at room temperature, and carrier-mediated magnetism is not likely to be applicable for the mechanisms of the magnetism in the films.

Microstructure and magnetic properties of Co-doped ZnO films deposited by gas flow sputtering

International Nuclear Information System (INIS)

Sakuma, H.; Watanabe, Y.; Aramaki, K.; Yun, K.S.; Ishii, K.; Ikeda, Y.; Kondo, H.

2010-01-01

Co-doped ZnO films with a Co concentration of 8-20 at.% were fabricated using the low-energy process of gas flow sputtering. X-ray diffraction, X-ray photoelectron spectroscopy, and optical absorption measurements revealed that the Co ions replace Zn ions in the ZnO matrix and that the Co ions have an oxidation state of 2+. The magnetic properties of the film depend on the Co concentration. The plots of magnetization and inverse susceptibility vs. temperature indicate that the film with a high Co concentration (20 at.%) contains a ferromagnetic component, while that with a low Co concentration (8 at.%) contains an antiferromagnetic component. The film with an intermediate Co concentration (10 at.%) contains a ferromagnetic component with a low Curie temperature. Hysteresis was not found in magnetization curves for all the samples, including the sample at 5 K. The films exhibited a high resistivity of 4 x 10 7 -2 x 10 8 Ω cm at room temperature, and carrier-mediated magnetism is not likely to be applicable for the mechanisms of the magnetism in the films.

Magneto-optical and transport studies of ZnO-based dilute magnetic semiconductors

Energy Technology Data Exchange (ETDEWEB)

Behan, A.J. [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom); Neal, J.R. [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom)]. E-mail: J.R.Neal@Sheffield.ac.uk; Ibrahim, R.M. [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom); Mokhtari, A. [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom); Ziese, M. [Universitaet Leipzig, Fakultaet fuer Physik und Geowissenschaften, Abteilung Supra leitung und Magnetismus, Linnestrasse 5, 04103 Leipzig (Germany); Blythe, H.J. [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom); Fox, A.M. [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom); Gehring, G.A. [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom)

2007-03-15

Thin film samples of ZnO doped with V were grown on sapphire substrates by pulsed laser deposition (PLD). The magnetization was measured by SQUID magnetometry and the films were found to be ferromagnetic at room temperature. The transmission, Faraday rotation and magnetic circular dichroism were measured as a function of frequency at room temperature over an energy range of 1.5-4.0 eV and carrier concentrations were determined from Hall effect measurements. Clear magneto-optical signals that are ferromagnetic in origin were observed at the ZnO band edge and the optimal conditions for observing large ferromagnetic magneto-optic signals are discussed.

Magnetic properties of polar ZnO surfaces from ab-initio calculations

Energy Technology Data Exchange (ETDEWEB)

Fischer, Guntram; Adeagbo, Waheed; Hergert, Wolfram [University Halle, Halle (Germany); Ernst, Arthur [Max-Planck-Institute of Microstructure Physics, Halle (Germany); Sanchez, Nadia; Mu noz, Carmen [Instituto de Ciencia de Materiales de Madrid, Madrid (Spain); Szotek, Zdzislawa; Temmerman, Walter [Daresbury Laboratory, Warrington (United Kingdom)

2011-07-01

We have investigated a magnetic moment formation of three oxygen-terminated polar ZnO surfaces. Specifically, these are the (000-1) surface, the (0001) surface with an oxygen atom on top of the Zn atom [(0001)-t], and the (0001) surface with an oxygen atom in a threefold hollow site [(0001)-h]. In this study we have used a multi-code approach allowing us to relax the surface structure and calculate the Heisenberg exchange parameters via a magnetic force theorem. Also, the influence of applying self-interaction corrections (SIC) to the oxygen p orbitals has been investigated. Our calculations show that all three surfaces are magnetic. In addition, we find that applying SIC is necessary to correctly describe the top oxygen atom of the (0001)-h and (0001)-t surfaces, for both of which we find Curie temperatures to be larger than room temperature. The latter have been derived from Monte Carlo simulations based on the calculated exchange parameters.

Paramagnetic ionic liquids for measurements of density using magnetic levitation.

Science.gov (United States)

Bwambok, David K; Thuo, Martin M; Atkinson, Manza B J; Mirica, Katherine A; Shapiro, Nathan D; Whitesides, George M

2013-09-03

Paramagnetic ionic liquids (PILs) provide new capabilities to measurements of density using magnetic levitation (MagLev). In a typical measurement, a diamagnetic object of unknown density is placed in a container containing a PIL. The container is placed between two magnets (typically NdFeB, oriented with like poles facing). The density of the diamagnetic object can be determined by measuring its position in the magnetic field along the vertical axis (levitation height, h), either as an absolute value or relative to internal standards of known density. For density measurements by MagLev, PILs have three advantages over solutions of paramagnetic salts in aqueous or organic solutions: (i) negligible vapor pressures; (ii) low melting points; (iii) high thermal stabilities. In addition, the densities, magnetic susceptibilities, glass transition temperatures, thermal decomposition temperatures, viscosities, and hydrophobicities of PILs can be tuned over broad ranges by choosing the cation-anion pair. The low melting points and high thermal stabilities of PILs provide large liquidus windows for density measurements. This paper demonstrates applications and advantages of PILs in density-based analyses using MagLev.

Structure and magnetic properties of iron-based soft magnetic composite with Ni-Cu-Zn ferrite-silicone insulation coating

Science.gov (United States)

Li, Wangchang; Wang, Wei; Lv, Junjun; Ying, Yao; Yu, Jing; Zheng, Jingwu; Qiao, Liang; Che, Shenglei

2018-06-01

This paper investigates the structure and magnetic properties of Ni-Cu-Zn ferrite-silicone coated iron-based soft magnetic composites (SMCs). Scanning electron microscopy coupled with a energy-dispersive spectroscopy (EDS) analysis revealed that the Ni-Cu-Zn ferrite and silicone resin were uniformly coated on the surface of iron powders. By controlling the composition of the coating layer, low total core loss of 97.7 mW/cm3 (eddy current loss of 48 mW/cm3, hysteresis loss of 49.7 mW/cm3, measured at 100 kHz and 0.02 T) and relatively high effective permeability of 72.5 (measured at 100 kHz) were achieved. In addition, the as-prepared SMCs displayed higher electrical resistivity, good magnetic characteristics over a wide range of frequencies (20-200 kHz) and ideal the D-C bias properties (more than 75% at H = 50 Oe). Furthermore, higher elastic modulus and hardness of SMCs, which means that the coating layer has good mechanical properties and is not easily damaged during the pressing process, were obtained in this paper. The results of this work indicate that the Ni-Cu-Zn ferrite-silicone coated SMCs have desirable properties which would make them suitable for application in the fields of the electric-magnetic switching devices, such as inductance coils, transformer cores, synchronous electric motors and resonant inductors.

Ionic Copolymer-Magnetite Complexes for Magnetic Resonance Imaging and Drug Delivery

OpenAIRE

Zhang, Rui

2015-01-01

This thesis is focused on the design, synthesis and characterization of magnetite-ionic copolymer complexes as nanocarriers for drug delivery and magnetic resonance imaging. The polymers included phosphonate and carboxylate-containing graft and block copolymers. Oleic-acid coated magnetite nanoparticles (8-nm and 16-nm diameters) were investigated. Cisplatin and carboplatin were used as sample drugs. The potentials of the magnetite-ionomer complexes as dual drug delivery carriers and magneti...

Intrinsic magnetism of a series of Co substituted ZnO single crystals

International Nuclear Information System (INIS)

Lv Peiwen; Huang Feng; Chu Wangsheng; Lin Zhang; Chen Dagui; Li Wei; Chen Dongliang; Wu Ziyu

2008-01-01

Magnetic properties of a series of well-substituted Zn 1-x Co x O (x = 0.018,0.036 and 0.05) single crystals were studied. A typical paramagnetic anisotropy property, which strengthens when x decreases, was found. A magnetization step was observed at 2 K when the magnetic field is parallel to the c axis, indicating that paramagnetic anisotropy is the origin of the strong crystal field effect on Co 2+ ions in ZnO lattices. The Co 2+ single-ion anisotropy parameter 2D is obtained as 7.5 K. The effective moment of Co 2+ takes the values 2.7 μ B , 1.82 μ B , 1.49 μ B when x = 0.018, 0.036 and 0.05, revealing that more antiferromagnetic coupling between Co 2+ ions arises in the perfect crystal when x increases

Self-Healing Natural Rubber with Tailorable Mechanical Properties Based on Ionic Supramolecular Hybrid Network.

Science.gov (United States)

Xu, Chuanhui; Cao, Liming; Huang, Xunhui; Chen, Yukun; Lin, Baofeng; Fu, Lihua

2017-08-30

In most cases, the strength of self-healing supramolecular rubber based on noncovalent bonds is in the order of KPa, which is a challenge for their further applications. Incorporation of conventional fillers can effectively enhance the strength of rubbers, but usually accompanied by a sacrifice of self-healing capability due to that the filler system is independent of the reversible supramolecular network. In the present work, in situ reaction of methacrylic acid (MAA) and excess zinc oxide (ZnO) was realized in natural rubber (NR). Ionic cross-links in NR matrix were obtained by limiting the covalent cross-linking of NR molecules and allowing the in situ polymerization of MAA/ZnO. Because of the natural affinity between Zn 2+ ion-rich domains and ZnO, the residual nano ZnO participated in formation of a reversible ionic supramolecular hybrid network, thus having little obstructions on the reconstruction of ionic cross-links. Meanwhile, the well dispersed residual ZnO could tailor the mechanical properties of NR by changing the MAA/ZnO molar ratios. The present study thus provides a simple method to fabricate a new self-healing NR with tailorable mechanical properties that may have more potential applications.

Nuclear Magnetic Resonance Study of Nanoscale Ionic Materials

KAUST Repository

Oommen, Joanna Mary

2010-08-13

Nanoscale ionic materials (NIMs) are a new class of nanomaterials that exhibit interesting properties including negligible vapor pressures and tunable physical states, among others. In this study, we analyzed the temperature-wise performance of NIMs using nuclear magnetic resonance (NMR) spectroscopy. NIMs are relatively stable over a temperature range from 300 to 383 K, rendering them usable in high temperature applications. We confirmed the presence of covalent bonds between the SiO2 core and the sulfonate group and determined relative concentrations of aromatic and aliphatic hydrocarbons. These findings serve as first hand proof-of-concept for the usefulness of NMR analyses in further studies on the diffusive properties of NIMs. © 2010 The Electrochemical Society.

Optical and magnetic resonance investigations of Zn1-x Mn x O magnetic semiconductors

International Nuclear Information System (INIS)

Zhang Huawei; Shi Erwei; Chen Zhizhan; Liu Xuechao; Xiao Bing; Song Lixin

2006-01-01

Zn 1- x Mn x O crystallites were synthesized by hydrothermal method. X-ray diffraction, UV-Vis absorption spectroscopy, and electron paramagnetic resonance (EPR) spectra confirm the substitution of Zn site by Mn 2+ ion. The nonmonotonic variation of band gap exhibits that the short-ranged interactions between the d electrons of Mn and the s and p electrons of the host bands are dominated at lower Mn concentration (x). EPR spectra show that Mn 2+ is in exchange interaction at higher x. By using a Curie-Weiss equation on the EPR data, it is found that the dominant magnetic property is antiferromagnetic for higher x, and paramagnetic for lower x

Structural and magnetic Ni-Zn ferrite synthesized by combustion reaction and sintered in a conventional oven

International Nuclear Information System (INIS)

Vieira, D.A.; Diniz, V.C.S.; Costa, A.C.F.M.; Kiminami, R.H.G.A.; Cornejo, D.R.

2011-01-01

The Ni-Zn ferrite due to their electrical and magnetic properties allows use in various technological applications. These properties can be controlled through appropriate choice of chemical composition, structural characteristics and morphology of the powders used and the techniques used for sintering. Thus, this study aims to evaluate the sintering in a conventional oven at a temperature of 1200 deg C/2h samples of Ni-Zn ferrite synthesized by microwave energy. The samples were characterized by density measurement, XRD, SEM and magnetic measurements. The results indicate the phase formation of Ni-Zn ferrite crystalline phase with crystallite size of 80 nm. The sample was heterogeneous microstructure with grain size of about 1 μm high intergranular porosity. The sample showed the saturation magnetization of 7.57 emu/g, coercive field and remanent magnetization close to zero, thus indicating a behavior characteristic of superparamagnetic materials. (author)

Magnetic and luminescent properties of vanadium-doped ZnSe crystals

Energy Technology Data Exchange (ETDEWEB)

Radevici, Ivan, E-mail: ivarad@utu.fi [Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Faculty of Physics and Engineering, Moldova State University, 60 A. Mateevici str., MD-2009 Chisinau (Moldova, Republic of); Nedeoglo, Natalia; Sushkevich, Konstantin [Faculty of Physics and Engineering, Moldova State University, 60 A. Mateevici str., MD-2009 Chisinau (Moldova, Republic of); Huhtinen, Hannu [Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Nedeoglo, Dmitrii [Faculty of Physics and Engineering, Moldova State University, 60 A. Mateevici str., MD-2009 Chisinau (Moldova, Republic of); Paturi, Petriina [Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland)

2016-12-15

Magnetic and photoluminescence properties of vanadium-doped ZnSe crystals with impurity concentrations varied by changing the V amount in the source material from 0.03 to 0.30 at% are studied in 5–300 K temperature range. Investigation of magnetic properties shows that the studied concentrations of vanadium impurity that should not disturb crystal lattice are insignificant for observing ferromagnetic behaviour even at low temperatures. The contribution of V impurity to edge emission and its influence on infra-red emission are discussed. Similarities of magnetic and luminescent properties induced by vanadium and other transition metal impurities are discussed.

Influence of La3+ Substitution on Structure, Morphology and Magnetic Properties of Nanocrystalline Ni-Zn Ferrite.

Directory of Open Access Journals (Sweden)

Y K Dasan

Full Text Available Lanthanum substituted Ni-Zn ferrite nanoparticles (Ni0.5Zn0.5LaxFe1-xO4; 0.00 ≤x≤ 1.00 synthesized by sol-gel method were presented. X-ray diffraction patterns reveal the typical single phase spinel cubic ferrite structure, with the traces of secondary phase for lanthanum substituted nanocrystals. In addition, the structural analysis also demonstrates that the average crystallite size varied in the range of 21-25 nm. FTIR spectra present the two prominent absorption bands in the range of 400 to 600 cm-1 which are the fingerprint region of all ferrites. Surface morphology of both substituted and unsubstituted Ni-Zn ferrite nanoparticle samples was studied using FESEM technique and it indicates a significant increase in the size of spherical shaped particles with La3+ substitution. Magnetic properties of all samples were analyzed using vibrating sample magnetometer (VSM. The results revealed that saturation magnetization (Ms and coercivity (Hc of La3+ substituted samples has decreased as compared to the Ni-Zn ferrite samples. Hence, the observed results affirm that the lanthanum ion substitution has greatly influenced the structural, morphology and magnetic properties of Ni-Zn ferrite nanoparticles.

Intrinsic magnetism of a series of Co substituted ZnO single crystals

Energy Technology Data Exchange (ETDEWEB)

Lv Peiwen [Laboratory of Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, National Engineering Research Center for Optoelectronic Crystalline Materials, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Huang Feng [Laboratory of Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, National Engineering Research Center for Optoelectronic Crystalline Materials, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Chu Wangsheng [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, 100049 Beijing (China); Lin Zhang [Laboratory of Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, National Engineering Research Center for Optoelectronic Crystalline Materials, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Chen Dagui [Laboratory of Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, National Engineering Research Center for Optoelectronic Crystalline Materials, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Li Wei [Laboratory of Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, National Engineering Research Center for Optoelectronic Crystalline Materials, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Chen Dongliang [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, 100049 Beijing (China); Wu Ziyu [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, 100049 Beijing (China)

2008-01-23

Magnetic properties of a series of well-substituted Zn{sub 1-x}Co{sub x}O (x = 0.018,0.036 and 0.05) single crystals were studied. A typical paramagnetic anisotropy property, which strengthens when x decreases, was found. A magnetization step was observed at 2 K when the magnetic field is parallel to the c axis, indicating that paramagnetic anisotropy is the origin of the strong crystal field effect on Co{sup 2+} ions in ZnO lattices. The Co{sup 2+} single-ion anisotropy parameter 2D is obtained as 7.5 K. The effective moment of Co{sup 2+} takes the values 2.7 {mu}{sub B}, 1.82 {mu}{sub B}, 1.49 {mu}{sub B} when x = 0.018, 0.036 and 0.05, revealing that more antiferromagnetic coupling between Co{sup 2+} ions arises in the perfect crystal when x increases.

Impact of ZnO substitution on magnetic response and microwave absorption capability of strontium-natural nanoferrites

Directory of Open Access Journals (Sweden)

W. Widanarto

2015-01-01

Full Text Available Ferrite being a compound derived from iron oxides including magnetite and hematite possesses similar properties as ceramics which are hard and brittle. Certainly, the mounting demand for electronics has been a major factor driving the exponential growth of ferrite based materials. ZnO doped strontium-natural nanoferrites of composition (80 − xFe2O3:xZnO:20SrCO3, where x = 0, 10, 20 mol% are synthesized and sintered via the solid state reaction scheme. Samples are characterized by SEM, XRD, VSM, and VNA measurements to determine the impact of ZnO contents’ variation on the surface morphology, structure, magnetic and microwave absorption properties. The Nicolson–Ross–Weir method is applied to evaluate samples’ reflection loss. The average grain size of the strontium ferrite is found to reduce with the increase in ZnO concentration. Materials sintered at 1100 °C without ZnO incorporation are composed of hexagonal SrFe12O19. Meanwhile, the addition of ZnO produces cubic ZnFe2O4 and SrFeO2 phases. Insertion of ZnO results in reduction of magnetic parameters and reflection loss. Furthermore, the anisotropy magnetic field of strontium natural ferrites displays a rapid drop from 350 kA/m to 79.6 kA/m with the increase in ZnO. Strontium ferrite containing 20 mol% of ZnO exhibits superior microwave absorption with reflection loss within −45 dB to −55.94 dB in the frequency range of 7–13 GHz. This facilely synthesized a new class of materials which is believed to be economically promising for microwave absorption applications in the GHz range.

A Mössbauer and magnetic study of ball milled Fe-doped ZnO Powders

Energy Technology Data Exchange (ETDEWEB)

Zamora, Ligia E., E-mail: ligia.zamora@correounivalle.edu.co; Paz, J. C.; Piamba, J. F.; Tabares, J. A.; Alcázar, G. A. Pérez [Universidad del Valle, Departamento de física (Colombia)

2015-06-15

The structural and magnetic properties of Fe-doped ZnO are reported in this study, as obtained by mechanical alloying from elemental powders of ZnO and Fe. The properties of Zn{sub 0.90}Fe{sub 0.10}O samples alloying while varying the milling time (6, 12, 24 and 36 h) are also reported. The Rietveld refinement of X-ray Diffraction (XRD) patterns revealed that the system presents two structures: the würtzite structure of ZnO and the bcc structure of α-Fe. The Mössbauer spectra show that the samples present three components: a ferromagnetic component, associated with the Fe phase and two paramagnetic components, associated with the Fe atoms, which penetrate inside the ZnO matrix behaving as Fe{sup 3+} and Fe{sup 2+}. The milling time contributes to an increase in the paramagnetic sites, and a solubility limit of the Fe atoms in the ZnO lattice was detected. The VSM measurements at room temperature detected ferromagnetic behavior with a saturation magnetization of 11 emu/g and a coercive field of 330 Oe for the sample alloyed over 24 h. A similar behavior was shown by the other samples.

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

International Nuclear Information System (INIS)

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

2011-01-01

Magnetic nanofibers of ZnFe 2 O 4 /γ-Fe 2 O 3 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 phase composition, particle size and magnetic properties have been investigated. Zinc ferrite fibers were obtained by calcinating the electrospun fibers in air from 300 to 800 deg. 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. An increase in 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 ZnFe 2 O 4 /γ-Fe 2 O 3 diphase crystals. The highest saturation magnetization (45 emu/g) was obtained for fibers calcined at 800 deg. C. - Research highlights: → Nanofibers were produced by electrospinning from a sol-gel. → ZnFe 2 O 4 /γ-Fe 2 O 3 formed after cacination in air from 300 to 800 deg. C. → Fibers were ferrimagnetic with high saturation magnetization. → Crystallite particle size and saturation magnetization increase with temperature. → Magnetic domains with sizes similar to topographical grains were observed.

Structural and Magnetic Properties of Mn doped ZnO Thin Film Deposited by Pulsed Laser Deposition

KAUST Repository

Baras, Abdulaziz

2011-07-01

Diluted magnetic oxide (DMO) research is a growing field of interdisciplinary study like spintronic devices and medical imaging. A definite agreement among researchers concerning the origin of ferromagnetism in DMO has yet to be reached. This thesis presents a study on the structural and magnetic properties of DMO thin films. It attempts to contribute to the understanding of ferromagnetism (FM) origin in DMO. Pure ZnO and Mn doped ZnO thin films have been deposited by pulsed laser deposition (PLD) using different deposition conditions. This was conducted in order to correlate the change between structural and magnetic properties. Structural properties of the films were characterized using x-ray diffraction (XRD) and scanning electron microscopy (SEM). The superconducting quantum interference device (SQUID) was used to investigate the magnetic properties of these films. The structural characterizations showed that the quality of pure ZnO and Mn doped ZnO films increased as oxygen pressure (PO) increased during deposition. All samples were insulators. In Mn doped films, Mn concentration decreased as PO increased. The Mn doped ZnO samples were deposited at 600˚C and oxygen pressure from 50-500mTorr. All Mn doped films displayed room temperature ferromagnetism (RTFM). However, at 5 K a superparamagnetic (SPM) behavior was observed in these samples. This result was accounted for by the supposition that there were secondary phase(s) causing the superparamagnetic behavior. Our findings hope to strengthen existing research on DMO origins and suggest that secondary phases are the core components that suppress the ferromagnetism. Although RTFM and SPM at low temperature has been observed in other systems (e.g., Co doped ZnO), we are the first to report this behavior in Mn doped ZnO. Future research might extend the characterization and exploration of ferromagnetism in this system.

Magnetic properties of ZnFe2O4 nanoparticles produced by a low-temperature solid-state reaction method

International Nuclear Information System (INIS)

Li Fashen; Wang Haibo; Wang Li; Wang Jianbo

2007-01-01

ZnFe 2 O 4 nanoparticles with average grain size ranging from 40 to 60 nm behaving superparamagnetic at room temperature have been produced using a low-temperature solid-state reaction (LTSSR) method without ball-milling process. Abnormal magnetic properties such as S-shape hysteresis loops and non-zero magnetic moments were observed. ZnFe 2 O 4 nanoparticles were also synthesized using a NaOH coprecipitation method and a PVA sol-gel method to study the relationship between the preparation processes and the magnetic properties. Spin-glass behavior was observed in the low temperature solid-state reaction produced Zn ferrite in the zero-field cooled (ZFC) measurement. Our work proves that the various preparation methods will to some extent determine the properties of magnetic nanoparticles

TUNABLE MAGNETIC AND ELECTRICAL PROPERTIES OF Co-DOPED ZnO FILMS BY VARYING OXYGEN PARTIAL PRESSURE

OpenAIRE

L. G. WANG; H. W. ZHANG; X. L. TANG; Y. X. LI; Z. Y. ZHONG

2011-01-01

High quality Co-doped ZnO films with good reproducibility have been prepared under different oxygen partial pressure by radio-frequency magnetron sputtering. These films were characterized using numerous characterization techniques including X-ray diffraction, electrical transport, and magnetization measurements. The effect of oxygen partial pressure on the structural, magnetic, and electrical properties of Co-doped ZnO films has been systematically studied. It was found that the structural, ...

Transition metal oxide nanopowder and ionic liquid: an efficient system for the synthesis of diorganyl selenides, selenocysteine and derivatives

Energy Technology Data Exchange (ETDEWEB)

Narayanaperumal, Senthil; Gul, Kashif; Kawasoko, Cristiane Y.; Singh, Devender; Dornelles, Luciano; Rodrigues, Oscar E.D. [Universidade Federal de Santa Maria (UFSC), RS (Brazil). Dept. de Quimica. LabSelen-NanoBio; Braga, Antonio L. [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Quimica. LabSelen

2010-07-01

We have developed an efficient method for the synthesis of diorganyl selenides and {beta}-seleno amines using Zn, catalytic amounts of ZnO nanopowder, as a catalyst and ionic liquid as a recyclable solvent. This ZnO/ionic liquid system shows high efficiency in catalyzing these transformations with the formation of the desired products in high yields. (author)

Magnetic phase change in Mn-doped ZnSnAs2 thin films depending on Mn concentration

Science.gov (United States)

Uchitomi, Naotaka; Hidaka, Shiro; Saito, Shin; Asubar, Joel T.; Toyota, Hideyuki

2018-04-01

The relationship between Mn concentration and Curie temperature (TC) is studied for Mn-doped ZnSnAs2 ferromagnetic semiconductors, epitaxially grown on InP substrates by molecular beam epitaxy. In the ferromagnetic phase, Mn distributions in a (Zn,Mn,Sn)As2 thin film with 7.2 cation percent (cat. %) Mn are investigated using three-dimensional atom probe tomography. The results indicate an inhomogeneous distribution which spreads to a relatively high Mn concentration of 9.0 at. % (at. %). In the paramagnetic phase, it is found that the paramagnetic to ferromagnetic transition takes place sharply with a TC of 334 K when the Mn doping concentration increases to about 4 cat. % Mn, which corresponds to a magnetic percolation threshold for ferromagnetism in (Zn,Mn,Sn)As2. An effective Curie temperature ⟨TC⟩ is considered to bridge the Curie temperatures obtained experimentally to those calculated theoretically in inhomogeneous magnetic semiconductors. The behavior of magnetism in Mn-doped ZnSnAs2 can be explained by three different phases within the present framework.

Are Fe and Co implanted ZnO and III-nitride semiconductors magnetic?

CERN Document Server

AUTHOR|(CDS)2081284; Bharuth-Ram, Krish

The chemical nature, lattice site locations and magnetic behaviour of Fe and/or Co ions implanted in nitrides (GaN, AlN, and InN) and in ZnO have been investigated using Mössbauer spectroscopy and vibrating sample magnetometer (VSM) techniques. Mössbauer data on nitride and $^{56}$Fe pre-implanted ZnO samples were obtained from emission Mössbauer spectroscopy (eMS) measurements at the ISOLDE facility, CERN, following the implantation of radioactive $^{57}$Mn$^{*}$ which $\\beta$$^{-}$decays to the 14.4 keV Mössbauer state of $^{57}$Fe. In addition, conversion electron Mössbauer spectroscopy (CEMS) data were collected on ZnO single crystals co-implanted with $^{57}$Fe + $^{56}$Fe and $^{57}$Fe + $^{59}$Co ions in a box profile. Emission Mössbauer spectra obtained for GaN and AlN reveal magnetic structure in the ‘wings’ assigned to high spin Fe$^{3+}$ weakly coupled to the lattice showing spin-lattice relaxation effects. The observed spin-relaxation rate (τ$^{-1}$) closely follows a ${T}^{2}$ temperat...

Growth and Structural, Magnetic, and Magnetooptical Properties of ZnO Films Doped with a Fe57 3 d Impurity

Science.gov (United States)

Mezdrogina, M. M.; Aglikov, A. S.; Semenov, V. G.; Kozhanova, Yu. V.; Nefedov, S. G.; Shelukhin, L. A.; Pavlov, V. V.

2018-03-01

ZnO films obtained by high-frequency magnetron sputtering and doped with a Fe57 metallic 3 d impurity by the diffusion method are studied. The type of local environment of Fe57 impurity atoms on varying the deposition parameters of ZnO films is determined by Mössbauer spectroscopy. It is established that the ground state of Fe57 impurity atoms corresponds to metallic iron in the magnetically ordered state and there is a small fraction of Fe57 atoms with a local environment corresponding to the complex oxide Fe3O4, having the magnetically ordered state; there is also a fraction of iron atoms in the paramagnetic state. The magnetic and magnetooptical parameters of the films were measured using magnetooptic Kerr effect. The spectral dependences of the polar magnetooptic Kerr effect in ZnO(Fe57) films are measured in a photon energy range of 1.5-4.5 eV and simulated by the effective-medium method. It is established that ZnO(Fe57) possess an easy-plane magnetic anisotropy with a magnetization lying in the film plane.

Fabrication of magnetic Fe@ZnO_0_._6S_0_._4 nanocomposite for visible-light-driven photocatalytic inactivation of Escherichia coli

International Nuclear Information System (INIS)

Peng, Ziling; Wu, Dan; Wang, Wei; Tan, Fatang; Ng, Tsz Wai; Chen, Jianguo; Qiao, Xueliang; Wong, Po Keung

2017-01-01

Highlights: • Fe@ZnO_0_._6S_0_._4 was prepared by a facile two-step precipitation method. • Fe@ZnO_0_._6S_0_._4 exhibited high photocatalytic activity under LED lamp irradiation. • Fe@ZnO_0_._6S_0_._4 possessed good stability and reusability for bacterial inactivation. • Fe@ZnO_0_._6S_0_._4 could be easily collected from the reaction solution by a magnet. • The release rate of metal ions from nanocomposite was kept at a very low level. - Abstract: Bacterial inactivation by magnetic photocatalysts has now received growing interests due to the easy separation for recycle and reuse of photocatalysts. In this study, magnetic Fe@ZnO_0_._6S_0_._4 photocatalyst was prepared by a facile two-step precipitation method. Multiple techniques such as X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffused reflectance spectra (UV-vis DRS) and vibrating sample magnetometer (VSM) were employed to characterize the structure, morphology and physicochemical properties of the photocatalyst. The as-obtained Fe@ZnO_0_._6S_0_._4 possessing magnetic property was easily collected from the reaction system by a magnet. Under white light-emitting-diode (LED) lamp irradiation, Fe@ZnO_0_._6S_0_._4 nanocomposite could completely inactivate 7-log of Escherichia coli K-12 within 5 h. More importantly, almost no decrease of photocatalytic efficiency in bacterial inactivation was observed even after five consecutive cycles, demonstrating Fe@ZnO_0_._6S_0_._4 exhibited good stability for reuse. The low released rate of Fe"2"+/Fe"3"+ and Zn"2"+ from Fe@ZnO_0_._6S_0_._4 composite further indicated the photocatalyst showed low cytotoxicity to bacterium and high stability under LED lamp irradiation. Facile preparation, high photocatalytic efficiency, good stability and reusability, and magnetic recovery property endow Fe@ZnO_0_._6S_0_._4 nanocomposite to be a promising photocatalytic material

Study on electrical structure and magneto-optical properties of W-doped ZnO

Science.gov (United States)

Li, Yong; Hou, Qingyu; Zhao, Chunwang; Xu, Zhenchao

2018-04-01

For W-doping amounts ranging from 0.0417 to 0.0833, experimental UV-visible absorption spectra blue shift and red shift results have been reported in the literatures. However, there is few literature reported research on magnetic mechanism. To solve this problem, this study investigates the disagreement about blue shift and red shift results and research on magnetic mechanism. The band structures, density of states, absorption spectra and magnetism have been investigated using first-principles planewave ultrasoft pseudopotential method based on the density functional theory. The calculated results showed that increased W-doping amounts first increase the volumes, and then reduce the volumes, decrease the formation energies, and stabilize the doped system. The band gaps become narrower and the absorption spectrum exhibits a significant red shift in UV and visible light emission. Moreover, the covalent bond vertical to c-axis strengthens, and the ionic bond parallel to c-axis weakens. Increased W-doping amounts decrease the magnetism of doped system. The magnetism of doped system originates from the electron exchange among W-5d, O-2p and Zn-3d orbitals of the W-doped ZnO. In W double-doped system, the ferromagnetic Curie temperature can be above room temperature when the doped system has a longer W-W distance.

Bromine-rich Zinc Bromides: Zn6Br12(18-crown-6)2×(Br2)5, Zn4Br8(18-crown-6)2×(Br2)3, and Zn6Br12(18-crown-6)2×(Br2)2.

Science.gov (United States)

Hausmann, David; Feldmann, Claus

2016-06-20

The bromine-rich zinc bromides Zn6Br12(18-crown-6)2×(Br2)5 (1), Zn4Br8(18-crown-6)2×(Br2)3 (2), and Zn6Br12(18-crown-6)2×(Br2)2 (3) are prepared by reaction of ZnBr2, 18-crown-6, and elemental bromine in the ionic liquid [MeBu3N][N(Tf)2] (N(Tf)2 = bis(trifluoromethylsulfonyl)amide). Zn6Br12(18-crown-6)2×(Br2)5 (1) is formed instantaneously by the reaction. Even at room temperature, compound 1 releases bromine, which was confirmed by thermogravimetry (TG) and mass spectrometry (MS). The release of Br2 can also be directly followed by the color and density of the title compounds. With controlled conditions (2 weeks, 25 °C, absence of excess Br2) Zn6Br12(18-crown-6)2×(Br2)5 (1) slowly releases bromine with conconcurrent generation of Zn4Br8(18-crown-6)2×(Br2)3 (2) (in ionic liquid) and Zn6Br12(18-crown-6)2×(Br2)2 (3) (in inert oil). All bromine-rich zinc bromides contain voluminous uncharged (e.g., Zn3Br6(18-crown-6), Zn2Br4(18-crown-6)) or ionic (e.g., [Zn2Br3(18-crown-6)](+), [(Zn2Br6)×(Br2)2](2-)) building units with dibromine molecules between the Zn oligomers and partially interconnecting the Zn-containing building units. Due to the structural similarity, the bromine release is possible via crystal-to-crystal transformation with retention of the crystal shape.

Covalent Immobilization of Cellulase Using Magnetic Poly(ionic liquid) Support: Improvement of the Enzyme Activity and Stability.

Science.gov (United States)

Hosseini, Seyed Hassan; Hosseini, Seyedeh Ameneh; Zohreh, Nasrin; Yaghoubi, Mahshid; Pourjavadi, Ali

2018-01-31

A magnetic nanocomposite was prepared by entrapment of Fe 3 O 4 nanoparticles into the cross-linked ionic liquid/epoxy type polymer. The resulting support was used for covalent immobilization of cellulase through the reaction with epoxy groups. The ionic surface of the support improved the adsorption of enzyme, and a large amount of enzyme (106.1 mg/g) was loaded onto the support surface. The effect of the presence of ionic monomer and covalent binding of enzyme was also investigated. The structure of support was characterized by various instruments such as FT-IR, TGA, VSM, XRD, TEM, SEM, and DLS. The activity and stability of immobilized cellulase were investigated in the prepared support. The results showed that the ionic surface and covalent binding of enzyme onto the support improved the activity, thermal stability, and reusability of cellulase compared to free cellulase.

Fe-based soft magnetic composites coated with NiZn ferrite prepared by a co-precipitation method

Energy Technology Data Exchange (ETDEWEB)

Peng, Yuandong; Yi, Yi; Li, Liya; Ai, Hengyu; Wang, Xiaoxu [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Chen, Lulu [Jiangsu Eagle-globe Group Co., Ltd., Nantong 226600 (China)

2017-04-15

Fe powder was coated with NiZn ferrite by a co-precipitation method using chlorate as the raw material. Soft magnetic composites were manufactured via compaction and heat treatment of the coated powder. The coated powder and heat treated powder were analysed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Raman spectroscopy. Their magnetic properties were determined using a Quantum Design-Vibrating Sample Magnetometer (QD-VSM). The composites were analysed with SEM and EDS. The permeability and magnetic loss of the composites were measured with a B-H curve analyzer. The results show that, using the co-precipitation method, the raw precipitate was successfully prepared and coated the pure Fe powder and turned into spinel NiZn ferrite treated at 600 ℃ for 1 h. After heat treatment at 500 ℃ under air, the insulation coating layer of soft magnetic composite (SMC) was not destroyed and containing Fe, Ni, Zn and oxygen. The permeabilities of the SMC are stable at edge of the 2–200 kHz frequency range and the total loss was lower. - Graphical abstract: Scanning electron microscopy (SEM) images of Fe/(NiZn)Fe{sub 2}O{sub 4} composite powder heated at 600 ℃ for 1 h. - Highlights: • Fe particles were coated with (NiZn)Fe{sub 2}O{sub 4} via a co-precipitation and calcined method. • Coating layers were uniform and dense. • The permeabilities of the SMC are stable at edge of the 2–200 kHz frequency range.

Synthesis and characterization of heterobinuclear (La-Zn, Pr-Zn, Nd-Zn, Sm-Zn, Eu-Zn, Gd-Zn, Tb-Zn, Dy-Zn) azine-bridged complexes

International Nuclear Information System (INIS)

Singh, Bachcha; Srivastav, A.K.; Singh, P.K.

1997-01-01

Zinc(II) complex of 2-acetylpyridine salicyl aldazine (Haps) of the type Zn(aps) 2 (H 2 O) 2 has been synthesised. The reaction of Zn(aps) 2 (H 2 O) 2 with lanthanide chlorides, LnCl 3 (where Ln=La, Pr, Nd, Sm, Eu, Gd, Tb and Dy) yields azine-bridged heterobinuclear complexes of the formulae LnCl 3 Zn(aps) 2 (H 2 O) 2 . These complexes have been characterized by elemental analyses, molecular weight, conductance (solid and solution) and magnetic susceptibility measurements, mass, IR and electronic spectral data. X-ray powder diffraction data indicate the tetragonal unit lattice for Zn(aps) 2 (H 2 O) 2 and PrCl 3 Zn(aps) 2 (H 2 O) 2 . (author)

Magnetic properties of M0.3Fe2.7O4 (M = Fe, Zn and Mn) ferrites nanoparticles

Science.gov (United States)

Modaresi, Nahid; Afzalzadeh, Reza; Aslibeiki, Bagher; Kameli, Parviz

2018-06-01

In the present article a comparative study on the structural and magnetic properties of nano-sized M0.3Fe0.7Fe2O4 (M = Fe, Zn and Mn) ferrites have been reported. The X-ray diffraction (XRD) patterns show that the crystallite size depends on the cation distribution. The Rietveld refinement of XRD patterns using MAUD software determines the distribution of cations and unit cell dimensions. The magnetic measurements show that the maximum and minimum value of saturation magnetization is obtained for Zn and Mn doped samples, respectively. The peak temperature of AC magnetic susceptibility of Zn and Fe doped samples below 300 K shows the superparamagnetic behavior in these samples at room temperature. the AC susceptibility results confirm the presence of strong interactions between the nanoparticles which leads to a superspin glass state in the samples at low temperatures.

Effect of iron doping concentration on magnetic properties of ZnO nanoparticles

International Nuclear Information System (INIS)

Sharma, Prashant K.; Dutta, Ranu K.; Pandey, Avinash C.; Layek, Samar; Verma, H.C.

2009-01-01

The ZnO:Fe nanoparticles of mean size 3-10 nm were synthesized at room temperature by simple co-precipitation method. The crystallite structure, morphology and size estimation were performed by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM). The wurtzite structure of ZnO gradually degrades with the increasing Fe doping concentration. The magnetic behavior of the nanoparticles of ZnO with varying Fe doping concentration was investigated using a vibrating sample magnetometer (VSM). Initially these nanoparticles showed strong ferromagnetic behavior, however at higher doping percentage of Fe, the ferromagnetic behavior was suppressed and paramagnetic nature was observed. The enhanced antiferromagnetic interaction between neighboring Fe-Fe ions suppressed the ferromagnetism at higher doping concentrations of Fe. Room-temperature Moessbauer spectroscopy investigation showed Fe 3+ nature of the iron atom in ZnO matrix.

Effect of γ-rays irradiation on the structural, magnetic, and electrical properties of Mg–Cu–Zn and Ni–Cu–Zn ferrites

Energy Technology Data Exchange (ETDEWEB)

Assar, S.T.; Abosheiasha, H.F., E-mail: Hatem_fouad@f-eng.tanta.edu.eg; El Sayed, A.R.

2017-01-01

Nanoparticles of Ni{sub 0.35}Cu{sub 0.15}Zn{sub 0.5}Fe{sub 2}O{sub 4} and Mg{sub 0.35}Cu{sub 0.15}Zn{sub 0.5}Fe{sub 2}O{sub 4}, have been synthesized by citrate precursor method. Then some of the prepared samples have been irradiated by γ-rays of {sup 60}Co radioactive source at room temperature with doses of 1 Mrad and 2 Mrad, at a dose rate of 0.1 Mrad/h to study the effect of γ-rays irradiation on some structural, magnetic and electrical properties of the samples. The X-ray diffraction analysis (XRD), transmission electron microscopy, Fourier transform infrared spectroscopy and vibrating sample magnetometer measurements have been used to investigate the samples. The XRD results show that the irradiation has caused a decrease in the crystallite size and the measured density and an increase in the porosity, specific surface area, and microstrain in the case of Ni–Cu–Zn ferrite whereas in the case of Mg–Cu–Zn ferrite the reverse trend has been noticed. The lattice constant of the investigated samples has been increased with the increase of irradiation due to the conversion of Fe{sup 3+} (0.67 Å) to Fe{sup 2+} (0.76 Å). The magnetization results show an increase in saturation and remnant magnetizations for the two prepared ferrites after γ-rays irradiation. The main reason of this behavior is most probably due to the redistribution of the cations between A and B sites. The cation distribution has been proposed such that the values of theoretical and experimental magnetic moment are identical and increase as the magnetization increases. Moreover, a theoretical estimation of the lattice constant has been calculated on the basis of the proposed cation distribution for each sample and compared with the corresponding experimental values obtained by XRD analysis; where they have been found in a good agreement with each other. This can be considered as another confirmation of the validity of the cation distribution. Moreover, the cation distribution is thought

The effects of Zn doping on magnetic properties of Cu3Bi(SeO3)2O2Cl

Science.gov (United States)

Yang, Pei-Ying; Tseng, Wu-Jyun; Wu, Hung-Cheng; Kakarla, D. Chandrasekhar; Yang, Hung-Duen; Department of Physics, Natl Sun Yat Sen Univ Team

Recently, layered spin-frustrated Cu3Bi(SeO3)2 O2Cl has received considerable research attention due to its unusual magnetic properties. Two inequivalent Cu2 + ions form a pseudo-kagome lattice that invokes spin frustration and anisotropic magnetic properties. In this study, the influence of Zn doping on the complex magnetic properties has been explored. Polycrystalline (Cu1-xZnx) Bi(SeO3)2 O2Cl (0 x 0.5) samples were synthesized using solid-state reaction and characterized by X-ray diffraction and magnetic measurements. The Zn doping strongly modulates the magnetic ground state of the system. The antiferromagnetic transition temperature TN = 24 K and magnetic field-induced hysteresis observed for x = 0 at low field are systematically shifted to lower temperature and reduced with Zn doping. These results can illustrate the insight of the occurrence of field-induced spin-flip type multiferroics in Cu3Bi(SeO3)2 O2Cl.

Structural and magnetic properties of Ni-Zn doped BaM nanocomposite via citrate precursor

International Nuclear Information System (INIS)

Rana, Kush; Thakur, Preeti; Thakur, Atul; Tomar, Monika; Gupta, Vinay

2016-01-01

Ni-Zn substituted M-type barium ferrite nanocomposite has been prepared via citrate precursor method. Nanocomposite having composition BaNi_0_._5Zn_0_._5Fe_1_1O_1_9 was sintered at 900°C for 3hrs and characterized by using different characterization techniques. X-ray diffraction (XRD) confirmed the formation of double phase with most prominent peak at (114). Average crystallite size for pure BaM and BNZFO were found to be 36 nm & 45 nm. Field emission scanning electron microscopy (FESEM) confirmed the formation of hexagonal platelets with a layered structure. Magnetic properties of these samples were investigated by using vibrating sample magnetometer (VSM). Magnetic parameters like saturation magnetization (M_s), coericivity (H_c) and squareness ratio (SQR) of nanocomposite were found to be 60 emu/g, 3663 Oe and 0.6163 respectively. These values were noticed to be higher as compared to pure BaM. Enhanced magnetic properties of nanocomposite were strongly dependent on exchange coupling. Therefore these properties make this nanocomposite a suitable candidate for magnetic recording and high frequency applications.

Effect of Zn and Ni substitution on structural, morphological and magnetic properties of tin oxide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Bhuvana, S. [Research and Development Centre, Bharathiar University, Coimbatore 641046, Tamilnadu (India); Department of Physics, Dr. NGP Institute of Technology, Coimbatore 641048, Tamilnadu (India); Ramalingam, H.B.; Vadivel, K. [Department of Physics, Government Arts College, Udumalpet 642126, Tamilnadu (India); Ranjith Kumar, E., E-mail: ranjueaswar@gmail.com [Department of Physics, Dr. NGP Institute of Technology, Coimbatore 641048, Tamilnadu (India); Ayesh, Ahmad I. [Department of Math., Stat. and Physics, Qatar University, Doha (Qatar)

2016-12-01

Structural, morphological, optical and magnetic properties of Zn and Zn–Ni co-doped tin oxide (SnO{sub 2}) nanoparticles synthesized by sol-gel method. The influence of doping concentration on phase and particle size of the nanoparticles was determined by X-ray diffraction. The XRD study reveals that the lattice constant and crystallite size of the samples decrease with the increase of doping concentration. The change in the band gap energy of SnO{sub 2} nanoparticles influenced more by doping with Zn and Ni. The external morphology and particle size were recorded by SEM and TEM. The results indicated that Ni{sup 2+} ions would uniformly substituted into the Zn{sup 2+} sites of SnO{sub 2} lattice. The substitution of Ni creates a vital change in magnetic properties that has been measured by vibrating sample magnetometer (VSM). - Highlights: • Sn{sub 2-(x+y)} Ni{sub x}Zn{sub y}O{sub 2}, (x=y=0.07 to 0.10) nano particles are prepared by simple sol gel method. • X-ray diffraction data confirms the single phase rutile tetragonal structure. • The VSM was used to confirm, the codoping of (Ni, Zn) increases the magnetic moment of the sample prepared. • Inducing ferromagnetism in sample makes it suitable for future spintronics applications.

Synthesis and characterization of ionic liquid immobilized on magnetic nanoparticles: A recyclable heterogeneous organocatalyst for the acetylation of alcohols

International Nuclear Information System (INIS)

Ghorbani-Choghamarani, Arash; Norouzi, Masoomeh

2016-01-01

Herein, we describe a simple and efficient procedure for the preparation of 3-((3-(trisilyloxy)propyl)propionamide)-1-methylimidazolium chloride ionic liquid supported on magnetic nanoparticle (TPPA–IL–Fe_3O_4). The structure of this magnetic ionic liquid is fully characterized by FT-IR, TGA, XRD, VSM, SEM, EDX and DLS techniques. TPPA–IL–Fe_3O_4 is employed as a catalyst for the acetylation of alcohols with acetic anhydride under mild and heterogeneous conditions at room temperature with good to excellent yields. The magnetic catalyst could be readily separate from the reaction media by simple magnetic decantation, and reused several times without significant loss of its catalytic activity. - Highlights: • TPPA–IL–Fe_3O_4 were prepared and well characterized. • TPPA–IL–Fe_3O_4 could be easily separated from solution with an external magnet. • The TPPA–IL–Fe_3O_4 was characterized by, FT-IR, SEM, TGA, DLS, EDS and VSM. • The catalytic activity of TPPA–IL–Fe_3O_4 was investigated in acetylation of alcohols.

Comprehensive studies of structural, electronic and magnetic properties of Zn0.95Co0.05O nanopowders

International Nuclear Information System (INIS)

Radisavljević, Ivana; Novaković, Nikola; Matović, Branko; Paunović, Novica; Medić, Mirjana; Bundaleski, Nenad; Andrić, Velibor; Teodoro, Orlando M.N.D.

2016-01-01

Highlights: • Zn 0.95 Co 0.05 O nanopowders are characterized by high structural order. • Co atoms show no tendency for Co–Co clustering and Co–Ov complexes formation. • Co–O–Co clustering along the c-axis has not lead to ferromagnetic order. • XMCD provides no evidence of magnetic polarization of O 2p and Co 3d states. - Abstract: X-ray absorption (XANES, EXAFS, XMCD) and photoelectron (XPS) spectroscopic techniques were employed to study local structural, electronic and magnetic properties of Zn 0.95 Co 0.05 O nanopowders. The substitutional Co 2+ ions are incorporated in ZnO lattice at regular Zn sites and the sample is characterized by high structural order. There was no sign of ferromagnetic ordering of Co magnetic moments and the sample is in paramagnetic state at all temperatures down to 5 K. The possible connection of the structural defects with the absence of ferromagnetism is discussed on the basis of theoretical calculations of the O K-edge absorption spectra.

Zn induced in-gap electronic states in La214 probed by uniform magnetic susceptibility: relevance to the suppression of superconducting T c

Science.gov (United States)

Islam, R. S.; Naqib, S. H.

2018-02-01

Substitution of isovalent non-magnetic defects, such as Zn, in the CuO2 plane strongly modifies the magnetic properties of strongly electron correlated hole doped cuprate superconductors. The reason for enhanced uniform magnetic susceptibility, χ, in Zn substituted cuprates is debatable. Generally the defect induced magnetic behavior has been analyzed mainly in terms of two somewhat contrasting scenarios. The first one is due to independent localized moments appearing in the vicinity of Zn arising because of the strong electronic/magnetic correlations present in the host compound and the second one is due to transfer of quasiparticle (QP) spectral weight and creation of weakly localized low-energy electronic states associated with each Zn atom in place of an in-plane Cu. If the second scenario is correct, one should expect a direct correspondence between Zn induced suppression of the superconducting transition temperature, T c, and the extent of the enhanced magnetic susceptibility at low temperature. In this case, the low-T enhancement of χ would be due to weakly localized QP states at low energy and these electronic states will be precluded from taking part in Cooper pairing. We explore this second possibility by analyzing the χ(T) data for La2-x Sr x Cu1-y Zn y O4 with different hole contents, p (=x), and Zn concentrations (y) in this paper. The results of our analysis support this scenario.

GGA+U investigations of impurity d-electrons effects on the electronic and magnetic properties of ZnO

KAUST Repository

Ul Haq, Bakhtiar

2014-08-01

Stimulation of novel features in ZnO by impurity electrons has attracted a remarkable attention of researchers from the past decade. Consequently, ZnO has found several applications in the field of spintronics and optoelectronics. We report, the effect of 3d-(V, Ag) electrons on the properties of ZnO in stable wurtzite (WZ) and metastable zincblende (ZB) phase using the density functional theory. Introduction of V-3d electrons was found to induce a high magnetic moment value of 5.22 in WZ and 3.26 in the ZB phase, and moreover transform the semiconductor character of ZnO into a metallic nature. Ag-d electrons result in the p-type half-metallic nature of ZnO with a weak ferromagnetic background. Our calculations for ground-state magnetic ordering show that ZnO in the presence of impure 3d-(V, Ag) electrons favors ferromagnetic ordering, and obey the double exchange mechanism. However, impurity atoms have very marginal effect on the lattice parameters of ZnO, thereby exposing its potential to absorb the impurity atoms in high concentration. © 2014 Elsevier B.V. All rights reserved.

Magnetic nanoparticles of NiCuZn tested in different conditions in catalysis for biodiesel

International Nuclear Information System (INIS)

Dantas, J.; Silva, F.N.; Silva, A.S.; Pereira, K.R.O.; Costa, A.C.F.M.

2014-01-01

In this work it was used magnetic nanoparticles Ni_0_,_2Cu_0_,_3Zn_0_,_5Fe_2O_4, chemical and thermally stable, under different conditions in catalysis for biodiesel. The magnetic characteristic of such material allows the catalyst recovery after the reactions by applying a permanent magnet. It was proposed to evaluate the performance of the nanomagnetic catalyst Ni_0_,_2Cu_0_,_3Zn_0_,_5Fe_2O_4 in the transesterification, modifying the processing variables (temperature, time, molar ratio of oil:alcohol and catalyst amount). The nanoparticles were synthesized by combustion reaction and characterized by XRD, TG, BET, magnetic measurements and gas chromatography. The results revealed the formation of inverse spinel phase, type B(AB)_2O_4, presenting isotherm profile classified as type V, with hysteresis loop of type 3 (H3). The magnetic hysteresis curve showed a characteristic behavior of soft magnetic material. GC analysis confirmed that nanoparticles were catalytically active, since they were superior to the reaction conducted without the catalyst presence. Besides, the reactions suffered considerable influence due to the changes of the independent variables. (author)

Magnetic Properties of Gadolinium-Doped ZnO Films and Nanostructures

KAUST Repository

Roqan, Iman S.

2016-08-29

The magnetic properties of Gd-doped ZnO films and nanostructures are important to the development of next-generation spintronic devices. Here, we elucidate the significant role played by Gd-oxygen-deficiency defects in mediating/inducing ferromagnetic coupling in in situ Gd-doped ZnO thin films deposited at low oxygen pressure by pulsed laser deposition (PLD). Samples deposited at higher oxygen pressures exhibited diamagnetic responses. Vacuum annealing was used on these diamagnetic samples (grown at a relatively high oxygen pressures) to create oxygen- deficiency defects with the aim of demonstrating reproducibility of room-temperature ferromagnetism (RTFM). Samples annealed at oxygen environment exhibited super‐ paramagnetism and blocking-temperature effects. The samples possessed secondary phases; Gd segregation led to superparamagnetism. Theoretical studies showed a shift of the 4f level of Gd to the conduction band minimum (CBM) in Gd-doped ZnO nanowires, which led to an overlap with the Fermi level, resulting in strong exchange coupling and consequently RTFM.

Fabrication of magnetic Fe@ZnO0.6S0.4 nanocomposite for visible-light-driven photocatalytic inactivation of Escherichia coli

Science.gov (United States)

Peng, Ziling; Wu, Dan; Wang, Wei; Tan, Fatang; Ng, Tsz Wai; Chen, Jianguo; Qiao, Xueliang; Wong, Po Keung

2017-02-01

Bacterial inactivation by magnetic photocatalysts has now received growing interests due to the easy separation for recycle and reuse of photocatalysts. In this study, magnetic Fe@ZnO0.6S0.4 photocatalyst was prepared by a facile two-step precipitation method. Multiple techniques such as X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffused reflectance spectra (UV-vis DRS) and vibrating sample magnetometer (VSM) were employed to characterize the structure, morphology and physicochemical properties of the photocatalyst. The as-obtained Fe@ZnO0.6S0.4 possessing magnetic property was easily collected from the reaction system by a magnet. Under white light-emitting-diode (LED) lamp irradiation, Fe@ZnO0.6S0.4 nanocomposite could completely inactivate 7-log of Escherichia coli K-12 within 5 h. More importantly, almost no decrease of photocatalytic efficiency in bacterial inactivation was observed even after five consecutive cycles, demonstrating Fe@ZnO0.6S0.4 exhibited good stability for reuse. The low released rate of Fe2+/Fe3+ and Zn2+ from Fe@ZnO0.6S0.4 composite further indicated the photocatalyst showed low cytotoxicity to bacterium and high stability under LED lamp irradiation. Facile preparation, high photocatalytic efficiency, good stability and reusability, and magnetic recovery property endow Fe@ZnO0.6S0.4 nanocomposite to be a promising photocatalytic material for bacterial inactivation.

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

International Nuclear Information System (INIS)

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

2017-01-01

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

Magnetic loss analysis in Mn-Zn ferrite cores

International Nuclear Information System (INIS)

Beatrice, C.; Bottauscio, O.; Chiampi, M.; Fiorillo, F.; Manzin, A.

2006-01-01

Magnetic losses have been measured and analyzed upon a wide range of frequencies in Mn-Zn ferrite ring cores. Exploiting the concept of loss separation and modeling the conductivity process in the heterogeneous material as a function of frequency, the role of the different energy dissipation mechanisms has been elucidated. It is shown, in particular, that eddy current effects can be appreciated, in standard materials and cores, only on approaching and overcoming the MHz range. The basic mechanism for hysteresis and low-frequency losses is therefore identified with the domain wall relaxation engendered by spin damping processes. Resonant absorption of energy associated with magnetization rotation is in turn deemed to chiefly contribute to the loss upon the practical range of frequencies going from a few 10 4 Hz to a few MHz

ZnFe2O4 Containing Nanoparticles: Synthesis and Magnetic Properties

Directory of Open Access Journals (Sweden)

Zālīte Ilmārs

2017-05-01

Full Text Available Solid solutions of Co1−xZnxFe2O4 and Ni1−xZnxFe2O4 (0 < x < 1 nanoparticles were synthesized by sol-gel self-propagating combustion method. The obtained single cubic phase product has a specific surface area 25 m2∙g−1 to 33 m2∙g−1 and crystallite size 25 nm to 40 nm. Lattice parameters change linearly from 8.371 A (CoFe2O4 and 8.337 A (NiFe2O4 to 8.431 A (ZnFe2O4. The saturation magnetization (Ms changes non-linearly from 60.8 emu∙g−1 (CoFe2O4, respectively, from 35.6 emu∙g−1 (NiFe2O4 to 3.3 emu∙g−1 (ZnFe2O4 reaching maximal value 76.1 emu∙g−1 for Co0.8Zn0.2Fe2O4 and 64.9 emu∙g−1 – for Ni0.6Zn0.4Fe2O4.

Manipulating the magnetism and resistance state of Mn:ZnO/Pb(Zr0.52Ti0.48)O3 heterostructured films through electric fields

Science.gov (United States)

Li, Yong-Chao; Wu, Jun; Pan, Hai-Yang; Wang, Jue; Wang, Guang-Hou; Liu, Jun-Ming; Wan, Jian-Guo

2018-05-01

Mn:ZnO/Pb(Zr0.52Ti0.48)O3 (PZT) heterostructured films have been prepared on Pt/Ti/SiO2/Si wafers by a sol-gel process. Nonvolatile and reversible manipulation of the magnetism and resistance by electric fields has been realized. Compared with the saturation magnetic moment (Ms) in the +3.0 V case, the modulation gain of Ms can reach 270% in the -3.0 V case at room temperature. The resistance change is attributed to the interfacial potential barrier height variation and the formation of an accumulation (or depletion) layer at the Mn:ZnO/PZT interface, which can be regulated by the ferroelectric polarization direction. The magnetism of Mn:ZnO originates from bound magnetic polarons. The mobile carrier variation in Mn:ZnO, owing to interfacial polarization coupling and the ferroelectric field effect, enables the electric manipulation of the magnetism in the Mn:ZnO/PZT heterostructured films. This work presents an effective method for modulating the magnetism of magnetic semiconductors and provides a promising avenue for multifunctional devices with both electric and magnetic functionalities.

RF and microwave noise suppression in a transmission line using Fe-Si-Al/Ni-Zn magnetic composite films

International Nuclear Information System (INIS)

Lee, J. W.; Hong, Y. K.; Kim, K.; Joo, J.; Yoon, Y. W.; Kim, S. W.; Kim, Y. B.; Kim, K. Y.

2006-01-01

Radio-frequency (RF) and microwave noise suppression by using magnetic composite films on a microstrip line (MSL) was studied in the frequency range from 50 MHz to 13.5 GHz. The MSL was composed of a Cu transmission line, dielectric materials, and a Cu substrate. The Fe-Si-Al/Ni-Zn magnetic composite films were placed on the MSL, and the reflection and the transmission characteristics were investigated. We observed that RF and microwave noise suppression caused by the Fe-Si-Al/Ni-Zn magnetic composite films varied with the concentration ratio of the sendust (Fe-Si-Al) and the Ni-Zn ferrite. The frequency dependence of the power loss due to the composite films on the MSL was measured and the power loss increased at higher frequencies with increasing concentration of the sendust in the composites. The electromagnetic interference shielding efficiencies of the magnetic composite films in the far-field region are also discussed.

Improvement of the magnetic moment of NiZn ferrites induced by substitution of Nd3+ ions for Fe3+ ions

Science.gov (United States)

Wu, Xuehang; Chen, Wen; Wu, Wenwei; Wu, Juan; Wang, Qing

2018-05-01

Four types of Ni-Zn based ferrites materials having the general formula Ni0.5Zn0.5NdxFe2-xO4 (0.0 ≤ x ≤ 0.12) have been successfully synthesized by calcining oxalates in air and the influence of Nd content on the structure and magnetic properties of Ni0.5Zn0.5NdxFe2-xO4 is studied. X-ray diffraction examination confirms that a high-crystallized Ni0.5Zn0.5NdxFe2-xO4 with cubic spinel structure is obtained when the precursor is calcined at 1000 °C in air for 2 h. The substitutions of Nd3+ ions for partial Fe3+ ions do not change the spinel crystalline structure of MFe2O4. The incorporation of Nd3+ ions in place of Fe3+ ions in Ni-Zn ferrites increases the average crystallite size. Specific saturation magnetization decreases with increase in Nd content. This is because Nd3+ ions with smaller magnetic moment preferentially fill the octahedral sites. In addition, antiferromagnetic FeNdO3 increases with increase in Nd content. In this study, Ni0.5Zn0.5Nd0.08Fe1.92O4, calcined at 1000 °C, exhibits the highest magnetic moment (4.2954 μB) and the lowest coercivity (28.82 Oe).

Structural and magnetic properties of Ni-Zn doped BaM nanocomposite via citrate precursor

Energy Technology Data Exchange (ETDEWEB)

Rana, Kush; Thakur, Preeti; Thakur, Atul, E-mail: atulphysics@gmail.com [School of Physics and Materials Science, Shoolini University, Solan, India 173212 (India); Tomar, Monika; Gupta, Vinay [Department of Physics and Astrophysics, University of Delhi, Delhi, India 110007 (India)

2016-05-23

Ni-Zn substituted M-type barium ferrite nanocomposite has been prepared via citrate precursor method. Nanocomposite having composition BaNi{sub 0.5}Zn{sub 0.5}Fe{sub 11}O{sub 19} was sintered at 900°C for 3hrs and characterized by using different characterization techniques. X-ray diffraction (XRD) confirmed the formation of double phase with most prominent peak at (114). Average crystallite size for pure BaM and BNZFO were found to be 36 nm & 45 nm. Field emission scanning electron microscopy (FESEM) confirmed the formation of hexagonal platelets with a layered structure. Magnetic properties of these samples were investigated by using vibrating sample magnetometer (VSM). Magnetic parameters like saturation magnetization (M{sub s}), coericivity (H{sub c}) and squareness ratio (SQR) of nanocomposite were found to be 60 emu/g, 3663 Oe and 0.6163 respectively. These values were noticed to be higher as compared to pure BaM. Enhanced magnetic properties of nanocomposite were strongly dependent on exchange coupling. Therefore these properties make this nanocomposite a suitable candidate for magnetic recording and high frequency applications.

Amendment of saturation magnetization, blocking temperature and particle size homogeneity in Mn-ferrite nanoparticles using Co-Zn substitution

Energy Technology Data Exchange (ETDEWEB)

Eltabey, M.M. [Basic Engineering Science Department, Faculty of Engineering, Menoufiya University (Egypt); Physics Department, Faculty of Science, Jazan University, Jazan (Saudi Arabia); Massoud, A.M., E-mail: Amassouda1@yahoo.com [Physics Department, Faculty of Science, Ain Shams University, Abbassia 11566, Cairo (Egypt); Radu, Cosmin [Lake Shore Cryotronics, Inc., Westerville, OH (United States)

2017-01-15

Nanocrystalline particles of compositions (CoZn){sub x}Mn{sub 1−x}Fe{sub 2}O{sub 4} were prepared by the coprecipitation method from stoichiometric aqueous solutions, where x varies from 0 to 0.3 in steps of 0.05. The synthesized powders were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and Fourier transform infrared spectroscopy (FT-IR). A vibrating sample magnetometer (VSM) was used to measure the hysteresis parameters at 300 and 6 K. Zero field cooling (ZFC) and field cooling (FC) curves were obtained at the temperature range 6–400 K and the blocking temperature values were determined. XRD analysis confirmed the formation of the obtained powder in a single cubic spinel phase and it showed also that the lattice parameter is decreasing with the increase of (Co-Zn) content. FT-IR measurements between 160 and 650 cm{sup −1} also confirmed the intrinsic cation vibrations of the spinel structure. The magnetic measurements showed that the saturation magnetization, coercivity and the values of blocking temperatures were increased with the (Co-Zn) content. TEM micrographs declared the improvement of particle size homogeneity with the increase of (Co-Zn) content without remarkable change in the average particle size. The obtained results were discussed in view of A-B sublattices interaction and superparamagnetic phenomenon. - Highlights: • Nanocrystalline particles of compositions (CoZn){sub x}Mn{sub 1-x}Fe{sub 2}O{sub 4} were prepared by the coprecipitation method. • XRD analysis showed that the lattice parameter is decreased with the increase of (Co,Zn) content. • The saturation magnetization is improved with the (Co,Zn) content. • Particle size homogeneity is enhanced with (Co,Zn) content. • The values of blocking temperatures are enhanced with increasing (Co,Zn) content.

High magnetoresistance at low magnetic fields in self-assembled ZnO-Co nanocomposite films.

Science.gov (United States)

Jedrecy, N; Hamieh, M; Hebert, C; Perriere, J

2017-07-27

The solid phase growth of self-assembled nanocrystals embedded in a crystalline host matrix opens up wide perspectives for the coupling of different physical properties, such as magnetic and semiconducting. In this work, we report the pulsed laser growth at room temperature of thin films composed of a dispersed array of ferromagnetic Co (0001) nanoclusters with an in-plane mono-size width of 1.3 nm, embedded in a ZnO (0001) crystalline matrix. The as-grown films lead to very high values of magnetoresistance, ranging at 9 T from -11% at 300 K to -19% at 50 K, with a steep decrease of the magnetoresistance at low magnetic fields. We establish the relationship between the magnetoresistance behavior and the magnetic response of the Co nanocluster assembly. A spin-dependent tunneling of the electrons between the Co nanoclusters through and by the semi-insulating ZnO host is achieved in our films, promising with regard to magnetic field sensors or Si-integrated spintronic devices. The effects of thermal annealing are also discussed.

Preparation of Cu{sub 2}ZnSnS{sub 4} thin films by sulfurizing stacked precursor thin films via successive ionic layer adsorption and reaction method

Energy Technology Data Exchange (ETDEWEB)

Su Zhenghua; Yan Chang; Sun Kaiwen; Han Zili [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China); Liu Fangyang, E-mail: liufangyang@csu.edu.cn [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China); Liu Jin [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China); Lai Yanqing, E-mail: laiyanqingcsu@163.com [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China); Li Jie; Liu Yexiang [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China)

2012-07-15

Earth-abundant Cu{sub 2}ZnSnS{sub 4} is a promising alternative photovoltaic material which has been examined as absorber layer of thin film solar cells. In this study, Cu{sub 2}ZnSnS{sub 4} (CZTS) thin films have been successfully fabricated by sulfurizing stacked precursor thin films via successive ionic layer adsorption and reaction (SILAR) method. The prepared CZTS thin films have been characterized by X-ray diffraction, energy dispersive spectrometer, Raman spectroscopy, UV-vis spectroscopy, Hall effect measurements and photoelectrochemical tests. Results reveal that the thin films have kesterite structured Cu{sub 2}ZnSnS{sub 4} and the p-type conductivity with a carrier concentration in the order of 10{sup 18} cm{sup -3} and an optical band gap of 1.5 eV, which are suitable for applications in thin film solar cells.

Fabrication and magnetic properties of Ni0.5Zn0.5Fe2O4 nanofibres by electrospinning

International Nuclear Information System (INIS)

Jun, Xiang; Xiang-Qian, Shen; Fu-Zhan, Song; Ming-Quan, Liu

2009-01-01

NiZn ferrite/polyvinylpyrrolidone composite fibres were prepared by sol–gel assisted electrospinning. Ni 0.5 Zn 0.5 Fe 2 O 4 nanofibres with a pure cubic spinel structure were obtained subsequently by calcination of the composite fibres at high temperatures. This paper investigates the thermal decomposition process, structures and morphologies of the electrospun composite fibres and the calcined Ni 0.5 Zn 0.5 Fe 2 O 4 nanofibres at different temperatures by thermo-gravimetric and differential thermal analysis, x-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The magnetic behaviour of the resultant nanofibres was studied by a vibrating sample magnetometer. It is found that the grain sizes of the nanofibres increase significantly and the nanofibre morphology gradually transforms from a porous structure to a necklace-like nanostructure with the increase of calcination temperature. The Ni 0.5 Zn 0.5 Fe 2 O 4 nanofibres obtained at 1000 °C for 2 h are characterized by a necklace-like morphology and diameters of 100–200 nm. The saturation magnetization of the random Ni 0.5 Zn 0.5 Fe 2 O 4 nanofibres increases from 46.5 to 90.2 emu/g when the calcination temperature increases from 450 to 1000 °C. The coercivity reaches a maximum value of 11.0 kA/m at a calcination temperature of 600 °C. Due to the shape anisotropy, the aligned Ni 0.5 Zn 0.5 Fe 2 O 4 nanofibres exhibit an obvious magnetic anisotropy and the ease magnetizing direction is parallel to the nanofibre axis. (condensed matter: structure, thermal and mechanical properties)

Dielectric and magnetic characterizations of capacitor structures with an ionic liquid/MgO barrier and a ferromagnetic Pt electrode

Directory of Open Access Journals (Sweden)

D. Hayakawa

2016-11-01

Full Text Available The dielectric and magnetic properties of electric double layer (EDL capacitor structures with a perpendicularly magnetized Pt/Co/Pt electrode and an insulating cap layer (MgO are investigated. An electric field is applied through a mixed ionic liquid/MgO barrier to the surface of the top Pt layer, at which the magnetic moment is induced by the ferromagnetic proximity effect. The basic dielectric properties of the EDL capacitor are studied by varying the thickness of the MgO cap layer. The results indicate that the capacitance, i.e., the accumulated charge density at the Pt surface, is reduced with increasing the MgO thickness. From the MgO thickness dependence of the capacitance value, the effective dielectric constant of the ionic liquid is evaluated. Almost no electric field effect on the magnetic moment, the coercivity, or the Curie temperature is confirmed in the top Pt layer with the thickness of 1.3 nm, regardless of the presence or absence of the MgO cap layer, whereas the a clear change in the magnetic moment is observed when the top Pt layer is replaced by a Pd layer of 1.7 nm.

Theoretical perspective on the electronic, magnetic and optical properties of Zn-doped monolayer SnS{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Sun, Lili; Zhou, Wei; Liu, Yanyu; Yu, Dandan [Department of Applied Physics, Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Faculty of Science, Tianjin University, Tianjin 300072 (China); Liang, Yinghua [College of Chemical Engineering, North China University of Science and Technology, Tangshan 063009 (China); Wu, Ping, E-mail: pingwu@tju.edu.cn [Department of Applied Physics, Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Faculty of Science, Tianjin University, Tianjin 300072 (China)

2016-12-15

Highlights: • The Zn doping in monolayer SnS{sub 2} is energetically favored under S-rich condition. • The room temperature ferromagnetism can be realized in Zn-doped monolayer SnS{sub 2}. • The Zn doping enhances the effective utilization in the near-infrared light region. • The Zn doping could lead to the red shift of absorption edge in monolayer SnS{sub 2}. • The Zn-doped monolayer SnS{sub 2} is active for both the oxygen and hydrogen evolution. - Abstract: The electronic, magnetic and optical properties of Zn-doped monolayer SnS{sub 2} have been theoretically investigated with the density functional theory. Numerical results reveal that monolayer SnS{sub 2} can be easily synthesized by cleaving its bulk crystal. Besides, the Zn doping in monolayer SnS{sub 2} is energetically favored under the S-rich with respect to the Sn-rich condition. The doped system exhibits the magnetic ground states due to the formation of defect states above the Fermi level, which are introduced by the hybridization between S-3p states and a small amount of Sn-4d states. The room temperature ferromagnetism can also be realized in Zn-doped monolayer SnS{sub 2}. The injection of Zn can enhance the absorption efficiency of solar spectrum, especially in the near-infrared light region. Moreover, the Zn doping can enhance the photocatalytic activity for both the oxygen and hydrogen evolution reactions in the monolayer SnS{sub 2}.

The Effect of a Spiral Gradient Magnetic Field on the Ionic Conductivity of Water

Czech Academy of Sciences Publication Activity Database

Bartušek, Karel; Marcon, P.; Fiala, P.; Máca, J.; Dohnal, P.

2017-01-01

Roč. 9, č. 9 (2017), s. 1-8, č. článku 664. ISSN 2073-4441 R&D Projects: GA ČR(CZ) GA17-00607S Institutional support: RVO:68081731 Keywords : gradient field * demineralized water * conductivity * ionic conductivity * magnetic field Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis) Impact factor: 1.832, year: 2016

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

Directory of Open Access Journals (Sweden)

S. Raghuvanshi

2018-04-01

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

Preparation of Mn-Zn ferrite nanoparticles and their silica-coated clusters: magnetic properties and transverse relaxivity

Czech Academy of Sciences Publication Activity Database

Kaman, Ondřej; Kuličková, Jarmila; Herynek, Vít; Koktan, Jakub; Maryško, Miroslav; Dědourková, T.; Knížek, Karel; Jirák, Zdeněk

2017-01-01

Roč. 427, Apr (2017), s. 251-257 ISSN 0304-8853 Institutional support: RVO:68378271 ; RVO:68378041 Keywords : magnetic nanoparticles * Mn-Zn ferrite * hydrothermal synthesis * magnetic resonance imaging * transverse relaxivity Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.630, year: 2016

Magnetic motion capture system using LC resonant magnetic marker composed of Ni-Zn ferrite core

International Nuclear Information System (INIS)

Hashi, S.; Toyoda, M.; Ohya, M.; Okazaki, Y.; Yabukami, S.; Ishiyama, K.; Arai, K. I.

2006-01-01

We have proposed a magnetic motion capture system using an LC resonant magnetic marker. The proposed system is composed of an exciting coil, an LC marker, and a 5x5-matrix search coil array (25 search coils). The LC marker is small and has a minimal circuit with no battery and can be driven wirelessly by the action of electromagnetic induction. It consists of a Ni-Zn ferrite core (3 mmφx10 mm) with a wound coil and a chip capacitor, forming an LC series circuit with a resonant frequency of 186 kHz. The relative position accuracy of the system is less than 1 mm within the area of 100 mm 3 up to 150 mm from the search coil array. Compared with dc magnetic systems, the proposed system is applicable for precision motion capture in optically isolated spaces without magnetic shielding because the system is not greatly influenced by earth field noise

Evaluation of structural, morphological and magnetic properties of CuZnNi (Cu_xZn_0_._5_−_xNi_0_._5Fe_2O_4) nanocrystalline ferrites for core, switching and MLCI’s applications

International Nuclear Information System (INIS)

Akhtar, Majid Niaz; Khan, Muhammad Azhar; Ahmad, Mukhtar; Nazir, M.S.; Imran, M.; Ali, A.; Sattar, A.; Murtaza, G.

2017-01-01

The influence of Cu substitution on the structural and morphological characteristics of Ni–Zn nanocrystalline ferrites have been discussed in this work. The detailed and systematic magnetic characterizations were also done for Cu substituted Ni–Zn nanoferrites. The nanocrystalline ferrites of Cu substituted Cu_xZn_0_._5_−_xNi_0_._5Fe_2O_4 ferrites (x=0, 0.1, 0.2, 0.3, 0.4 and 0.5) were synthesized using sol gel self-combustion hybrid method. X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscope (TEM) and Vibrating sample magnetometer (VSM) were used to investigate the properties of Cu substituted nanocrystalline ferrites. Single phase structure of Cu substituted in Ni–Zn nanocrystalline ferrites were investigated for all the samples. Crystallite size, lattice constant and volume of the cell were found to increase by increasing Cu contents in spinel structure. The better morphology with well-organized nanocrystals of Cu–Zn–Ni ferrites at x=0 and 0.5 were observed from both FESEM and TEM analysis. The average grain size was 35–46 nm for all prepared nanocrystalline samples. Magnetic properties such as coercivity, saturation, remanence, magnetic squareness, magneto crystalline anisotropy constant (K) and Bohr magneton were measured from the recorded M–H loops. The magnetic saturation and remanence were increased by the incorporation of Cu contents. However, coercivity follow the Stoner-Wolforth model except for x=0.3 which may be due to the site occupancy and replacement of Cu contents from octahedral site. The squareness ratio confirmed the super paramgnetic behaviour of the Cu substituted in Ni–Zn nanocrystalline ferrites. Furthermore, Cu substituted Ni–Zn nanocrystalline ferrites may be suitable for many industrial and domestic applications such as components of transformers, core, switching, and MLCI’s due to variety of the soft magnetic characteristics. - Highlights: • Cu substituted

Novel multifunctional NiFe_2O_4/ZnO hybrids for dye removal by adsorption, photocatalysis and magnetic separation

International Nuclear Information System (INIS)

Zhu, Hua-Yue; Jiang, Ru; Fu, Yong-Qian; Li, Rong-Rong; Yao, Jun; Jiang, Sheng-Tao

2016-01-01

Graphical abstract: - Highlights: • The NiFe_2O_4 was decorated on ZnO surface by a hydrothermal method. • NiFe_2O_4/ZnO hybrids show high adsorption capacity and excellent photostability. • The main active species in dye decolorization by NiFe_2O_4/ZnO hybrids are ·OH and h"+. • NiFe_2O_4/ZnO hybrids can be easily separated by an external magnet. - Abstract: Novel multifunctional NiFe_2O_4/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 NiFe_2O_4/ZnO hybrids were systematically investigated using congo red as a model contaminant. With the introduction of NiFe_2O_4, NiFe_2O_4/ZnO hybrids can absorb the whole light from 300 nm to 700 nm. The adsorption capacity (221.73 mg g"−"1) of NiFe_2O_4/ZnO hybrids is higher than those of NiFe_2O_4, ZnO and mechanically mixed NiFe_2O_4/ZnO hybrids. The removal of congo red solution (20 mg L"−"1) by NiFe_2O_4/ZnO hybrids was about 94.55% under simulated solar light irradiation for 10 min. ·OH and h"+ play important roles in the decolorization of congo red solution by NiFe_2O_4/ZnO hybrids under simulated solar light irradiation. The decolorization efficiency of congo red solution is 97.23% for the fifth time by NiFe_2O_4/ZnO hybrids under simulate solar light irradiation, indicating the high photostability and durability. NO_3"− and Cl"− anions which are ubiquitous components in dye-containing wastewater have negligible influence on the effectiveness of NiFe_2O_4/ZnO hybrids. Moreover, the magnetic NiFe_2O_4/ZnO hybrids can be easily separated from the reacted solution by an external magnet.

Magnetic and optical properties of manganese doped ZnO nanoparticles synthesized by sol-gel technique

KAUST Repository

Omri, Karim; El Ghoul, Jaber; Lemine, O. M.; Bououdina, M.; Zhang, Bei; El Mir, Lassaad

2013-01-01

Mn doped ZnO nanoparticles with different doping concentration (1, 2, 3, 4, 5 at.%) were prepared by sol-gel method using supercritical drying conditions of ethyl alcohol. The structural, morphological, optical and magnetic properties of the as-prepared nanoparticles were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV measurements and superconducting quantum interference device (SQUID). The structural properties showed that the undoped and Mn doped ZnO nanoparticles exhibit hexagonal wurtzite structure. From the optical studies, the transmittance in UV region was decreased with the increase of Mn concentration. For Mn doped ZnO nanoparticles the optical band gap varies between 3.34 eV and 3.22 eV. It was found that the doping Mn 2+ ions have a significant influence on the optical properties. The magnetic characterization of the samples with 1% and 5% Mn concentrations reveal diamagnetic behavior for the first one and the presence of both paramagnetic and ferromagnetic behavior for the second. The room ferromagnetic component is due to the presence of the secondary phase ZnOMn3 which is confirmed by XRD study. © 2013 Elsevier Ltd. All rights reserved.

Magnetic and optical properties of manganese doped ZnO nanoparticles synthesized by sol-gel technique

KAUST Repository

Omri, Karim

2013-08-01

Mn doped ZnO nanoparticles with different doping concentration (1, 2, 3, 4, 5 at.%) were prepared by sol-gel method using supercritical drying conditions of ethyl alcohol. The structural, morphological, optical and magnetic properties of the as-prepared nanoparticles were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV measurements and superconducting quantum interference device (SQUID). The structural properties showed that the undoped and Mn doped ZnO nanoparticles exhibit hexagonal wurtzite structure. From the optical studies, the transmittance in UV region was decreased with the increase of Mn concentration. For Mn doped ZnO nanoparticles the optical band gap varies between 3.34 eV and 3.22 eV. It was found that the doping Mn 2+ ions have a significant influence on the optical properties. The magnetic characterization of the samples with 1% and 5% Mn concentrations reveal diamagnetic behavior for the first one and the presence of both paramagnetic and ferromagnetic behavior for the second. The room ferromagnetic component is due to the presence of the secondary phase ZnOMn3 which is confirmed by XRD study. © 2013 Elsevier Ltd. All rights reserved.

Magnetic, hyperthermic and structural properties of zn substituted CaFe2O4 powders

Science.gov (United States)

Kheradmand, Abbas; Vahidi, Omid; Masoudpanah, S. M.

2018-03-01

In the present study, we have synthesized single phase Ca1 - x Zn x Fe2O4 powders by hydrothermal method. The cation distribution between the tetrahedral and octahedral sites in the spinel structure and the magnetic properties as a function of the zinc substitution have been investigated by X-ray diffraction (XRD), infrared spectroscopy and vibrating sample magnetometer methods. The obtained XRD pattern indicated that the synthesized particles had single phase cubic spinel structure with no impurity. The magnetic measurements showed that the saturation magnetization increased from 83 to 98 emu/g with the addition of zinc due to the decrease of inversity. The particle size observed by electron microscopy decreased from 1.38 to 0.97 µm with the increase of zinc addition. The Ca0.7Zn0.3Fe2O4 powders exhibited appropriate heating capability for hyperthermia applications with the maximum AC heating temperature of 20 °C and specific loss power of 9.29 W/g.

Temperature-dependent magnetism of Fe thin films on ZnSe(0 0 1)

International Nuclear Information System (INIS)

Cantoni, M.; Bertacco, R.; Ciccacci, F.; Puppin, E.; Pinotti, E.; Brenna, M.; Marangolo, M.; Eddrieff, M.; Torelli, P.; Maccherozzi, F.; Fujii, J.; Panaccione, G.

2007-01-01

We present X-ray magnetic circular dichroism (XMCD) and magneto-optical Kerr effect (MOKE) data on the magnetic properties of Fe/ZnSe(0 0 1) thin films at increasing Fe coverage. The magnetic behaviour of the Fe overlayer is superparamagnetic for a coverage up to 6 monolayers whereas, above this threshold, a truly ferromagnetic phase shows up. XMCD and MOKE data show that this behaviour is substantially unchanged in the temperature range 10-300 K for all the investigated coverages: these findings imply that the blocking temperature is definitely below 10 K

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

Energy Technology Data Exchange (ETDEWEB)

Nie Eryong; Liu Donglai; Zhang Yunsen; Bai Xue; Yi Liang; Jin Yong; Jiao Zhifeng [School of Materials Science and Engineering, Sichuan University, Chengdu 610064, Sichuan (China); Sun Xiaosong, E-mail: sunxs@scu.edu.cn [School of Materials Science and Engineering, Sichuan University, Chengdu 610064, Sichuan (China)

2011-08-15

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

Characterization of polymer-type ionic conductors using nuclear magnetic resonance and thermal analysis. Humidity sensor

International Nuclear Information System (INIS)

Cavalcante, Maria Goretti.

1992-04-01

We report a study using Nuclear Magnetic Resonance (NMR), Thermogravimetry Analysis, Differential Scanning Calorimetry and Infrared Spectroscopy in polymeric complexes formed poly(ethylene oxide), (PEO), and lithium salts. These complexes have have shown a large potential for technological applications in batteries, sensors, etc. We developed and characterized humidity sensors and discussed how the humidity affects the conformation of the complexes, the mobility of ionic species, and the polymeric chains. The results indicate that the hydration affects the conformation of polymeric complexes by plasticizing the water, which induces a volumetric expansion in the PEO chain. The processes was completely reversible for the level of hydration studied. NMR was used to distinguish the movement of polymeric chains from the movement of the ionic species. From the analysis of the second moment of resonance lines from the study of the nuclear relaxation we were able to estimate the average distance between the ionic species and the proton in the complexes chains. The behaviour of spin -lattice relaxation of hydrogen and fluorine in the P(EO) - Li B F, as a function of temperature and frequency reflects the nature of the disorder and the complexity of the ionic conduction process in these materials. (author). 91 refs., 69 figs., 2 tabs

A comparative study on magnetism in Zn-doped AlN and GaN from first-principles

International Nuclear Information System (INIS)

Xu, Liang; Wang, Lingling; Huang, Weiqing; Xiao, Wenzhi; Xiao, Gang

2014-01-01

First-principles calculations have been used to comparatively investigate electronic and magnetic properties of Zn-doped AlN and GaN. A total magnetic moment of 1.0 μ B induced by Zn is found in AlN, but not in GaN. Analyses show that the origin of spontaneous polarization not only depend on the localized atomic orbitals of N and sufficient hole concentration, but also the relative intensity of the covalency of matrix. The relatively stronger covalent character of GaN with respect to AlN impedes forming local magnetic moment in GaN matrix. Our study offers a fresh sight of spontaneous spin polarization in d 0 magnetism. The much stronger ferromagnetic coupling in c-plane of AlN means that it is feasible to realize long-range ferromagnetic order via monolayer delta-doping. This can apply to other wide band-gap semiconductors in wurtzite structure.

Influence of cold isostatic pressing on the magnetic properties of Ni-Zn-Cu ferrite

Directory of Open Access Journals (Sweden)

Trong Trung Le

2018-04-01

Full Text Available In power electronics, there is the need to develop solutions to increase the power density of converters. Interleaved multicellular transformers allow interleaving many switching cells and, as a result, a possible increase in the power density. This converter is often composed of a magnetic core having the function of an intercell transformer (ICT and, depending on the complexity of the designed architecture, its shape could be extremely complex. The switching frequencies (1-10 MHz for the new wide band gap semiconductors (SiC, GaN allow to interleave switching cell at higher frequencies than silicon-based semiconductors (<1 MHz. Intercell transformers must follow this increase in frequency times-fold the number of switching cells. Current applications for ICT transformers use Mn-Zn based materials, but their limit in frequency drive raises the need of higher frequency magnetic materials, such Ni-Zn ferrites. These materials can operate in medium and high power converters up to 10 MHz. We propose to use Ni0,30Zn0,57Cu0,15Fe2O4 ferrite and to compress it by cold isostatic pressing (CIP into a a green ceramic block and to machine it to obtain the desired ICT of complex shape prior sintering. We compare the magnetic permeability spectra and hysteresis loops the CIP and uniaxially pressed ferrites. The effect of temperature and sintering time as well as high-pressure on properties will be presented in detail. The magnetic properties of the sintered cores are strongly dependent on the microstructure obtained.

Bioaccumulation of Zn and Ag Nanoparticles in the Earthworms (Eisenia fetida)

Science.gov (United States)

Ha, Lee Seung; Sung-Dae, Kim; Yi, Yang Song; Byeong-Gweon, Lee

2014-05-01

Many studies are carried out to evaluate environmental effects of engineered nanoparticles (ENPs). Most of the previous studies primarily focused on the effects of nanoparticles into the aquatic environment and human. Model studies predict that ENPs released into environment would transferred primarily to the soil of the terrestrial environment. Despite this prediction, biogeochemical behavior of ENPs in soil environment as well as bioavailability of ENPs to soil-dwelling organisms such as earthworm, springtail, isopod and nematodes are poorly understood. The main goal of this study was to compare the bioaccumulation factor (BAFs) and subcellular partitioning of nanoparticles in the soil-dwelling earthworm (Eisenia fetida) from ENP (ZnO and Ag nanoparticles) or ionic metal (Zn2+, Ag+) contaminated soil. And the sequential extraction was also used to determine the mobility of metals in soil which could be used as to predict bioavailability and compare that with bioaccumulation factor. The radiotracer method was employed to trace the transfer of ENPs and ionic metal among different environmental media and animals. Radiolabeled 65ZnO, 110mAgNPs coated with PVP or citrate were synthesized in the laboratory and their chemical and biological behavior was compared to ionic 65Zn and 110mAg. The BAFs of Zn and Ag in the earthworms were determined after animals exposed to the contaminated soils. After the 7 days of elimination phase, subcellular partitioning of metals were also obtained. BAF for ZnO(0.06) was 31 times lower than that for Zn ion (1.86), suggesting that ZnO was less bioavailable than its ionic form from contaminated soil. On the other hands, BAFs for AgNPs coated with PVP (0.12) or with citrate (0.11) were comparable to those for Ag ion (0.17), indicating that Ag from contaminated soil was bioavailable in a similar rate regardless of chemical forms. The subcellular partitioning results showed that bioaccumulated Zn from Zn ion and ZnO contaminated soil were

Fabrication of magnetic Fe@ZnO{sub 0.6}S{sub 0.4} nanocomposite for visible-light-driven photocatalytic inactivation of Escherichia coli

Energy Technology Data Exchange (ETDEWEB)

Peng, Ziling [State Key Laboratory of Material Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, Hubei (China); Wu, Dan [School of Life Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong Special Administrative Region (China); Wang, Wei, E-mail: weiwang@hust.edu.cn [State Key Laboratory of Material Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, Hubei (China); Tan, Fatang [State Key Laboratory of Material Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, Hubei (China); Ng, Tsz Wai [School of Life Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong Special Administrative Region (China); Chen, Jianguo; Qiao, Xueliang [State Key Laboratory of Material Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, Hubei (China); Wong, Po Keung, E-mail: pkwong@cuhk.edu.hk [School of Life Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong Special Administrative Region (China)

2017-02-28

Highlights: • Fe@ZnO{sub 0.6}S{sub 0.4} was prepared by a facile two-step precipitation method. • Fe@ZnO{sub 0.6}S{sub 0.4} exhibited high photocatalytic activity under LED lamp irradiation. • Fe@ZnO{sub 0.6}S{sub 0.4} possessed good stability and reusability for bacterial inactivation. • Fe@ZnO{sub 0.6}S{sub 0.4} could be easily collected from the reaction solution by a magnet. • The release rate of metal ions from nanocomposite was kept at a very low level. - Abstract: Bacterial inactivation by magnetic photocatalysts has now received growing interests due to the easy separation for recycle and reuse of photocatalysts. In this study, magnetic Fe@ZnO{sub 0.6}S{sub 0.4} photocatalyst was prepared by a facile two-step precipitation method. Multiple techniques such as X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffused reflectance spectra (UV-vis DRS) and vibrating sample magnetometer (VSM) were employed to characterize the structure, morphology and physicochemical properties of the photocatalyst. The as-obtained Fe@ZnO{sub 0.6}S{sub 0.4} possessing magnetic property was easily collected from the reaction system by a magnet. Under white light-emitting-diode (LED) lamp irradiation, Fe@ZnO{sub 0.6}S{sub 0.4} nanocomposite could completely inactivate 7-log of Escherichia coli K-12 within 5 h. More importantly, almost no decrease of photocatalytic efficiency in bacterial inactivation was observed even after five consecutive cycles, demonstrating Fe@ZnO{sub 0.6}S{sub 0.4} exhibited good stability for reuse. The low released rate of Fe{sup 2+}/Fe{sup 3+} and Zn{sup 2+} from Fe@ZnO{sub 0.6}S{sub 0.4} composite further indicated the photocatalyst showed low cytotoxicity to bacterium and high stability under LED lamp irradiation. Facile preparation, high photocatalytic efficiency, good stability and reusability, and magnetic recovery property endow Fe@ZnO{sub 0

First-principles study on electronic and magnetic properties of (Mn,Fe)-codoped ZnO

International Nuclear Information System (INIS)

Cao, Huawei; Lu, Pengfei; Cai, Ningning; Zhang, Xianlong; Yu, Zhongyuan; Gao, Tao; Wang, Shumin

2014-01-01

First-principle calculations have been performed to investigate the electronic and magnetic properties of (Mn,Fe)-codoped ZnO within the generalized gradient approximation (GGA) and GGA+U schemes. The formation energy of five different configurations is investigated and the ground state is demonstrated to be ferromagnetic ordering. By applying the U correction, the band gap energy of pure ZnO is close to the experimental values, while the ferromagnetic ordering of the ground state remains unchanged. The ferromagnetic stabilization is mediated by double exchange mechanism. In addition, defects corresponding to Zn-vacancy and O-vacancy cannot enhance the ferromagnetism obviously. These results indicate that (Mn,Fe)-codoped ZnO are promising magneto-electronic and spintronic materials. - Highlights: • We have considered 5 different configurations of Mn/Fe codoped bulk ZnO. • The formation energy is calculated to investigate the structural stability. • The double exchange mechanism is responsible for the ferromagnetic behavior. • Defects are not effective method to get room temperature ferromagnetism. • Mn/Fe codoped ZnO are promising ferromagnetic semiconductor materials

First-principles study on electronic and magnetic properties of (Mn,Fe)-codoped ZnO

Energy Technology Data Exchange (ETDEWEB)

Cao, Huawei [Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education, Beijing 100876 (China); Lu, Pengfei, E-mail: photon.bupt@gmail.com [Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education, Beijing 100876 (China); Cai, Ningning; Zhang, Xianlong; Yu, Zhongyuan [Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education, Beijing 100876 (China); Gao, Tao [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Wang, Shumin [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Photonics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Gothenburg (Sweden)

2014-02-15

First-principle calculations have been performed to investigate the electronic and magnetic properties of (Mn,Fe)-codoped ZnO within the generalized gradient approximation (GGA) and GGA+U schemes. The formation energy of five different configurations is investigated and the ground state is demonstrated to be ferromagnetic ordering. By applying the U correction, the band gap energy of pure ZnO is close to the experimental values, while the ferromagnetic ordering of the ground state remains unchanged. The ferromagnetic stabilization is mediated by double exchange mechanism. In addition, defects corresponding to Zn-vacancy and O-vacancy cannot enhance the ferromagnetism obviously. These results indicate that (Mn,Fe)-codoped ZnO are promising magneto-electronic and spintronic materials. - Highlights: • We have considered 5 different configurations of Mn/Fe codoped bulk ZnO. • The formation energy is calculated to investigate the structural stability. • The double exchange mechanism is responsible for the ferromagnetic behavior. • Defects are not effective method to get room temperature ferromagnetism. • Mn/Fe codoped ZnO are promising ferromagnetic semiconductor materials.

Effect of nickel doping concentration on structural and magnetic properties of ultrafine diluted magnetic semiconductor ZnO nanoparticles

International Nuclear Information System (INIS)

Sharma, Prashant K.; Dutta, Ranu K.; Pandey, Avinash C.

2009-01-01

The ZnO:Ni 2+ nanoparticles of mean size 2-12 nm were synthesized at room temperature by the simple co-precipitation method. The crystallite structure, morphology and size were determined by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The wurtzite structure of ZnO gradually degrades with the increasing Ni doping concentration and an additional NiO-associated diffraction peak was observed above 15% of Ni 2+ doping. The change in magnetic behavior of the nanoparticles of ZnO with varying Ni 2+ doping concentration was investigated using a vibrating sample magnetometer (VSM). Initially, these nanoparticles showed strong ferromagnetic behavior, however, at higher doping percentage of Ni 2+ , the ferromagnetic behavior was suppressed and paramagnetic nature was observed. The enhanced antiferromagnetic interaction between neighboring Ni-Ni ions suppressed the ferromagnetism at higher doping concentrations of Ni 2+ .

Magnetic properties of Zn0.9(Mn0.05,Ni0.05)O nanoparticle: Experimental and theoretical investigation

Science.gov (United States)

Mounkachi, O.; Lakhal, M.; Labrim, H.; Hamedoun, M.; Benyoussef, A.; El Kenz, A.; Loulidi, M.; Bhihi, M.

2012-06-01

The crystalline and magnetic properties of 5% Mn and 5% Ni co-doped nanocrystalline ZnO particles, obtained by the co-precipitation method, are performed. X-ray diffraction data revealed that Zn0.90Mn0.05Ni0.05O crystallizes in the monophasic wurtzite structure. DC magnetization measurement showed that the samples are paramagnetic at room temperature. However, a large increase in the magnetization is observed below 50 K. This behavior, along with the negative value of Weiss constant obtained from the linear fit of magnetic susceptibility data below room temperature, indicates ferrimagnetic behavior. The ferrimagnetic properties observed at low temperature are explained and confirmed from ab-initio calculations using the Korringa-Kohn-Rostoker method combined with the coherent potential approximation.

Comprehensive studies of structural, electronic and magnetic properties of Zn{sub 0.95}Co{sub 0.05}O nanopowders

Energy Technology Data Exchange (ETDEWEB)

Radisavljević, Ivana, E-mail: iva@vin.bg.ac.rs [University of Belgrade—Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade (Serbia); Novaković, Nikola; Matović, Branko [University of Belgrade—Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade (Serbia); Paunović, Novica [University of Belgrade—Institute of Physics, Pregrevica 118, 11000 Belgrade (Serbia); Medić, Mirjana [University of Belgrade—Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade (Serbia); Bundaleski, Nenad [University of Belgrade—Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade (Serbia); Universidade Nova de Lisboa—Faculdade de Ciências e Tecnologia, Quinta da Torre 2829-516 Caparica (Portugal); Andrić, Velibor [University of Belgrade—Vinča Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade (Serbia); Teodoro, Orlando M.N.D. [Universidade Nova de Lisboa—Faculdade de Ciências e Tecnologia, Quinta da Torre 2829-516 Caparica (Portugal)

2016-02-15

Highlights: • Zn{sub 0.95}Co{sub 0.05}O nanopowders are characterized by high structural order. • Co atoms show no tendency for Co–Co clustering and Co–Ov complexes formation. • Co–O–Co clustering along the c-axis has not lead to ferromagnetic order. • XMCD provides no evidence of magnetic polarization of O 2p and Co 3d states. - Abstract: X-ray absorption (XANES, EXAFS, XMCD) and photoelectron (XPS) spectroscopic techniques were employed to study local structural, electronic and magnetic properties of Zn{sub 0.95}Co{sub 0.05}O nanopowders. The substitutional Co{sup 2+} ions are incorporated in ZnO lattice at regular Zn sites and the sample is characterized by high structural order. There was no sign of ferromagnetic ordering of Co magnetic moments and the sample is in paramagnetic state at all temperatures down to 5 K. The possible connection of the structural defects with the absence of ferromagnetism is discussed on the basis of theoretical calculations of the O K-edge absorption spectra.

Magnetic and microstructural properties of Ni-Zn ferrites synthesized and sintered by microwave energy; Propriedades magneticas e microestruturais de ferritas Ni-Zn sintetizadas e sinterizadas oir energia de microondas

Energy Technology Data Exchange (ETDEWEB)

Vieira, D.A.; Diniz, V.C.S.; Sousa, J-P.LM.L.; Costa, A.C.F.M. [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Dept. de Engenharia de Materiais; Kiminami, R.H.G.A. [Universidade Federal de Sao Carlos (UFScar), SP (Brazil). Dept. de Engenharia de Materiais; Cornejo, D.R. [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica

2009-07-01

The soft ferrites (or soft) and the Ni-Zn type are composed of spinel with cubic structure, which exhibit a permanent magnetization, called ferrimagnetism. Thus, this work will be assessed the structure and magnetic properties of ferrites Ni{sub 0},{sub 5}Zn{sub 0},{sub 5}Fe{sub 2}O{sub 4} prepared by combustion reaction using microwave energy as a source of heat and urea as fuel and after sintering by microwave energy. The synthesized powders were compacted by uniaxial pressing. The synthesized powders and the samples after sintering were characterized by XRD, SEM and magnetic measures. The diffractogram X-ray powder and the sintered samples showed the presence of the desired phase Ni{sub 0},{sub 5}Zn{sub 0},{sub 5}Fe{sub 2}O{sub 4} in both cases. The powders and sintered samples resulted in the Ms value of 8.09 emu/g and 67.73 emu/g, respectively. (author)

Magnetic properties of the semimagnetic semiconductor Zn0.15Mn0.85Ga2Se4

International Nuclear Information System (INIS)

Cadenas, Ruben; Perez, Flor V.; Quintero, Miguel; Quintero, Eugenio; Tovar, Rafael; Morocoima, Manuel; Gonzalez, Jesus; Bocaranda, P.; Ruiz, J.; Broto, J.M.; Rakoto, H.

2007-01-01

We report on the magnetic measurements of the semimagnetic semiconductor Zn 0.15 Mn 0.85 Ga 2 Se 4 (ZMGSe). The DC susceptibility and high magnetic field indicate that the ZMGSe orders antiferromagnetically at T∼6 K and undergoes into a spin-flop phase below this temperature. Arrott plots and magnetic entropy changes were used to characterize the order of the transitions

Structural, chemical and magnetic properties of secondary phases in Co-doped ZnO

DEFF Research Database (Denmark)

Ney, A; Kovács, András; Ney, V

2011-01-01

, chemical and magnetic properties of Co-doped ZnO samples. It can be established on a quantitative basis that the superparamagnetic (SPM) behavior observed by integral superconducting quantum interference device magnetometry is not an intrinsic property of the material but stems from precipitations...

Optical and magnetic resonance investigations of Zn{sub 1-} {sub x} Mn {sub x} O magnetic semiconductors

Energy Technology Data Exchange (ETDEWEB)

Zhang Huawei [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Shi Erwei [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Chen Zhizhan [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)]. E-mail: zzchen@mail.sic.ac.cn; Liu Xuechao [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Xiao Bing [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Song Lixin [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

2006-10-15

Zn{sub 1-} {sub x} Mn {sub x} O crystallites were synthesized by hydrothermal method. X-ray diffraction, UV-Vis absorption spectroscopy, and electron paramagnetic resonance (EPR) spectra confirm the substitution of Zn site by Mn{sup 2+} ion. The nonmonotonic variation of band gap exhibits that the short-ranged interactions between the d electrons of Mn and the s and p electrons of the host bands are dominated at lower Mn concentration (x). EPR spectra show that Mn{sup 2+} is in exchange interaction at higher x. By using a Curie-Weiss equation on the EPR data, it is found that the dominant magnetic property is antiferromagnetic for higher x, and paramagnetic for lower x.

Magnetic properties of the compound Zn(Mnsub(0.98)Fesub(0.02)2O4

International Nuclear Information System (INIS)

Wautelet, M.; Gerard, A.

1975-01-01

Moessbauer spectra were measured of the compound Zn(Mnsub(0.98)Fesub(0.02)) 2 O 4 at several temperatures between 4.2 and 77 K. Evaluation of the spectra showed that the Neel temperature of ZnMn 2 O 4 does not exceed 50 K; the magnetic structure seems to be the same as that of Mn 3 O 4 with predominant B-B interactions. (A.K.)

Static and quasi-elastic small angle neutron scattering on biocompatible ionic ferrofluids: magnetic and hydrodynamic interactions

CERN Document Server

Gazeau, F; Dubois, E; Perzynski, R

2003-01-01

We investigate the structure and dynamics of ionic magnetic fluids (MFs), based on ferrite nanoparticles, dispersed at pH approx 7 either in H sub 2 O or in D sub 2 O. Polarized and non-polarized static small angle neutron scattering (SANS) experiments in zero magnetic field allow us to study both the magnetic and the nuclear contributions to the neutron scattering. The magnetic interparticle attraction is probed separately from the global thermodynamic repulsion and compares well to direct magnetic susceptibility measurements. The magnetic interparticle correlation is in these fluid samples independent of the probed spatial scale. In contrast, a spatial dependence of the interparticle correlation is evidenced at large PHI by the nuclear structure factor. A model of magnetic interaction quantitatively explains the under-field anisotropy of the SANS nuclear contribution. In a quasi-elastic neutron spin-echo experiment, we probe the Brownian dynamics of translation of the nanoparticles in the range 1.3 sup<=...

Optical studies of 2DEGs in ZnSe quantum wells in high magnetic fields.

Energy Technology Data Exchange (ETDEWEB)

Ossau, Wolfgang J.; Astakhov, G. V.; Yakovlev, D. R.; Crooker, S. A. (Scott A.); Waag, A.

2002-01-01

Optical properties of a two-dimensional electron gas in ZnSe/(Zn,Be,Mg)Se quantum well structures have been examined by means of photoluminescence and reflectivity techniques in external magnetic fields up to 50 T. For these structures the Fermi energy of the two-dimensional electron gas is falling in the range between the trion binding energy and the exciton binding energy, which keeps the dominating role of Coulombic interaction between electrons and photoexcited holes. Characteristic peculiarities of optical spectra are discussed.

Influence of Zn{sup 2+} content on morphological and magnetic properties of Mn{sub 1-x}Zn{sub x}Fe{sub 2}O{sub 4} ferrites synthesized on a large scale by combustion reaction; Influencia do teor de Zn{sup 2+} nas caracteristicas morfologicas e magneticas de ferritas Mn{sub 1-x}Zn{sub x}Fe{sub 2}O{sub 4} sintetizados em grande escala por reacao de combustao

Energy Technology Data Exchange (ETDEWEB)

Diniz, V.C.S.; Silveira Junior, J.E.R.; Costa, A.C.F.M., E-mail: veronicacristhina@hotmail.com, E-mail: juniorramos_1@hotmail.com, E-mail: c_r_i_s_2005@yahoo.com.br [Universidade Federal de Campina Grande (UFCG), Campina Grande, PB (Brazil). Departamento de Engenharia de Materiais; Cornejo, D.R., E-mail: cornejo@if.usp.br [Universidade de Sao Paulo (USP), SP (Brazil). Instituto de Fisica; Kiminami, R.H.G.A., E-mail: ruth@ufscar.br [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Engenharia de Materiais

2017-04-15

This study aimed to evaluate the influence of Zn{sup 2+} in the morphological and magnetic characteristics of ferrites Mn{sub 1-x}Zn{sub x} Fe{sub 2} O{sub 4} (where x= 0.0, 0.35, 0.5 and 0.65 mol of Zn) synthesized by combustion reaction in a pilot scale with batches of 200 g/reaction. The samples were characterized by X-ray diffraction, scanning/transmission electron microscopy, and magnetic measurements. The results indicated that all compositions were single phase of ferrite; morphologically the addition of Zn to MnFe{sub 2} O{sub 4} system caused a slight reduction in size of the agglomerates, and reduced the particle size, but this behavior was not linear with the Zn{sup 2+} content. The samples had characteristic magnetic behavior of soft magnetic materials, maximum saturation magnetization of 62 emu/g for the sample with lower zinc content in its composition. (author)

Structure and soft magnetic properties of sputter deposited MnZn-ferrite films

NARCIS (Netherlands)

Gillies, M.F.; Coehoorn, R.; van Zon, J.B.A.D.; Alders, D.

1998-01-01

In this paper we report the soft magnetic properties of thin films of sputtered MnZn ferrite deposited on thermally oxidized Si substrates. A high deposition temperature, 600¿°C, together with the addition of water vapor to the sputtering gas was found to improve the initial ac permeability, µ. The

Structural and magnetic properties of size-controlled Mn0.5Zn0 ...

Indian Academy of Sciences (India)

Abstract. Mn0.5Zn0.5Fe2O4 ferrite nanoparticles with tunable Curie temperature and saturation ... netic fluid is synthesized and magnetic characterization is reported. The monolayer ... the synthesis method – largely affects the macroscopic properties, giving rise to a wide variety of ..... available in sample C. TGA technique ...

Magnetic and dielectric properties of the ruthenium double perovskites La2MRuO6 (M=Mg, Co, Ni, and Zn)

International Nuclear Information System (INIS)

Yoshii, Kenji; Ikeda, Naoshi; Mizumaki, Masaichiro

2006-01-01

Magnetic and dielectric properties of the ruthenium double perovskites La 2 MRuO 6 (M=Mg, Co, Ni, and Zn) were investigated. The magnetization measurements for M=Co and Ni showed the existence of magnetic order at 20-30 K. Though the oxides with M=Zn and Mg exhibit a deviation from the Curie-Weiss law, magnetic order was not clearly observed. The result of La 2 ZnRuO 6 was different from that previously reported, in which a ferromagnetic transition was found at around 165 K. The AC dielectric measurements for M = Co and Ni showed large dielectric constants (typically larger than 1000) at around room temperature, suggesting both the formation of short-ranged polar regions and the magnetic origin of large dielectric constant. In addition, two peaks were found for the temperature dependence of the tan δ component for La 2 NiRuO 6 . The behavior suggests the existence of two different polar regions. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (Abstract Copyright [2006], Wiley Periodicals, Inc.)

Defects induced magnetic transition in Co doped ZnS thin films: Effects of swift heavy ion irradiations

Energy Technology Data Exchange (ETDEWEB)

Patel, Shiv P., E-mail: shivpoojanbhola@gmail.com [Physics Department, University of Allahabad, Allahabad 211002 (India); Pivin, J.C. [CSNSM, IN2P3-CNRS, Batiment 108, F-91405 Orsay Campus (France); Patel, M.K; Won, Jonghan [Materials Science and Technology Division, MST-8, P.O.Box 1663, Mail Stop G755, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Chandra, Ramesh [Nanoscience Laboratory, IIC, Indian Institute of Technology, Roorkee 247667 (India); Kanjilal, D. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Kumar, Lokendra [Physics Department, University of Allahabad, Allahabad 211002 (India)

2012-07-15

The effect of swift heavy ions (SHI) on magnetic ordering in ZnS thin films with Co ions substituted on Zn sites is investigated. The materials have been synthesized by pulsed laser deposition on substrates held at 600 Degree-Sign C for obtaining films with wurtzite crystal structure and it showed ferromagnetic ordering up to room temperature with a paramagnetic component. 120 MeV Ag ions have been used at different fluences of 1 Multiplication-Sign 10{sup 11} ions/cm{sup 2} and 1 Multiplication-Sign 10{sup 12} ions/cm{sup 2} for SHI induced modifications. The long range correlation between paramagnetic spins on Co ions was destroyed by irradiation and the material became purely paramagnetic. The effect is ascribed to the formation of cylindrical ion tracks due to the thermal spikes resulting from electron-phonon coupling. - Highlights: Black-Right-Pointing-Pointer Effect of swift heavy ions on magnetic ordering in Co doped ZnS thin films are presented. Black-Right-Pointing-Pointer Magnetization in the pristine films is composed of ferromagnetic and paramagnetic components. Black-Right-Pointing-Pointer The films become purely paramagnetic after swift heavy ions irradiation. Black-Right-Pointing-Pointer The magnetic transition is ascribed to the formation of ion track (or cylindrical defects) due to the thermal spikes.

Preparation of Mn-Zn ferrite nanoparticles and their silica-coated clusters: Magnetic properties and transverse relaxivity

Energy Technology Data Exchange (ETDEWEB)

Kaman, Ondřej, E-mail: kamano@seznam.cz [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic); Kuličková, Jarmila [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic); Herynek, Vít [Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, 140 21 Praha 4 (Czech Republic); Koktan, Jakub [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic); University of Chemistry and Technology, Prague, Technická 5, 166 28 Praha 6 (Czech Republic); Maryško, Miroslav [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic); Dědourková, Tereza [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic); University of Pardubice, Doubravice 41, 532 10 Pardubice (Czech Republic); Knížek, Karel; Jirák, Zdeněk [Institute of Physics, AS CR, Cukrovarnická 10, 162 00 Praha 6 (Czech Republic)

2017-04-01

Hydrothermal synthesis of Mn{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} nanoparticles followed by direct encapsulation of the as-grown material into silica is demonstrated as a fast and facile method for preparation of efficient negative contrast agents based on clusters of ferrite crystallites. At first, the hydrothermal procedure is optimized to achieve strictly single-phase magnetic nanoparticles of Mn-Zn ferrites in the compositional range of x≈0.2–0.6 and with the mean size of crystallites ≈10 nm. The products are characterized by powder X-ray diffraction, X-ray fluorescence spectroscopy, and SQUID magnetometry, and the composition close to x=0.4 is selected for the preparation of silica-coated clusters with the mean diameter of magnetic cores ≈25 nm. Their composite structure is studied by means of transmission electron microscopy combined with detailed image analysis and magnetic measurements in DC fields. The relaxometric studies, performed in the magnetic field of B{sub 0}=0.5 T, reveal high transverse relaxivity (r{sub 2}(20 °C)=450 s{sup −1} mmol(Me{sub 3}O{sub 4}){sup −1} L) with a pronounced temperature dependence, which correlates with the observed temperature dependence of magnetization and is ascribed to a mechanism of transverse relaxation similar to the motional averaging regime. - Highlights: • Mn-Zn ferrite particles with size of ≈10 nm are synthesized by hydrothermal method. • Their structure and magnetic properties are analysed in dependence on composition. • Silica-coated clusters with the size ≈26 nm are prepared as contrast agent for MRI. • Their transverse relaxivity shows strong temperature dependence.

Radiation induced structural and magnetic transformations in nanoparticle MnxZn(1−x)Fe2O4 ferrites

International Nuclear Information System (INIS)

Naik, P.P.; Tangsali, R.B.; Sonaye, B.; Sugur, S.

2015-01-01

Nanoparticle magnetic materials are suitable for multiple modern high end medical applications like targeted drug delivery, gene therapy, hyperthermia and MR thermometry imaging. Majority of these applications are confined to use of Mn–Zn ferrite nanoparticles. These nanoparticles are normally left in the body after their requisite application. Preparing these nanoparticles is usually a much involved job. However with the development of the simple technique Mn x Zn 1−x Fe 2 O 4 nanoparticles could be prepared with much ease. The nanoparticles of Mn x Zn 1−x Fe 2 O 4 with (x=1.0, 0.7, 0.5, 0.3, 0.0) were prepared and irradiated with gamma radiation of various intensities ranging between 500 R to 10,000 R, after appropriate structural and magnetic characterization. Irradiated samples were investigated for structural and magnetic properties, as well as for structural stability and cation distribution. The irradiated nanoparticles exhibited structural stability with varied cation distribution and magnetic properties, dependent on gamma radiation dose. Surprisingly samples also exhibited quenching of lattice parameter and particle size. The changes introduced in the cation distribution, lattice constant, particle size and magnetic properties were found to be irreversible with time lapse and were of permanent nature exhibiting good stability even after several months. Thus the useful properties of nanoparticles could be enhanced on modifying the cation distribution inside the nanoparticles by application of gamma radiation. - Highlights: • Mn x Zn 1−x Fe 2 O 4 nanoparticles were synthesized using auto combustion method. • The irradiated samples showed a change in cation distribution. • Lattice shrinkage observed due to radiation induced change in cation distribution. • Reduction in particle size was also observed due to gamma exposure. • An enhancement in saturation magnetization was observed in irradiated samples

The electronic, magnetic and optical properties of ZnO doped with doubles impurities (Cr, Fe): An LDA-SIC and Monte Carlo study

Energy Technology Data Exchange (ETDEWEB)

Salmani, El Mehdi, E-mail: elmehdisalmani@gmail.com [LMPHE, Faculté des Sciences, Université Mohammed V, Rabat (Morocco); Laghrissi, Ayoub; Lamouri, Rachida; Ez-Zahraouy, Hamid [LMPHE, Faculté des Sciences, Université Mohammed V, Rabat (Morocco); Benyoussef, Abdelilah [Institute for Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Académie Hassan II des Sciences et Techniques, Rabat (Morocco)

2017-01-15

Electronic structure, magnetic and optical properties of ZnO doped with single and double impurities Zn{sub 1−x}Cr{sub x}O, Zn{sub 1−x}Fe{sub x}O, and Zn{sub 1−2x}Cr{sub x}Fe{sub x}O (x=0.03 and 0.06) are investigated using first-principles calculations. Based on the Korringa–Kohn–Rostoker method combined with the coherent potential approximation, we investigated the half-metallic ferromagnetic behavior of doubles impurities (Cr, Fe) doped ZnO. To support our results, we apply the self-interaction-corrected local density approximation (SIC-LDA) to study the electronic structure, optical and magnetic properties of Co-doped ZnO with doubles impurities (Cr, Fe) showing that the half-metallic ferromagnetic state still persists. The stability of the ferromagnetic state compared with the spin-glass state is investigated by comparing their total energies. The exchange interactions obtained from first principle calculations and used in a classical Ising model by a Monte Carlo approach resulted in ferromagnetic states with high Neel temperature. - Highlights: • The electronic structure calculations for ZnO doped with doubles impurities (Cr, Fe) have been discussed. • The half-metallic aspect was proven to take place for doubles impurities (Cr, Fe) codoped ZnO. • The doubles impurities (Cr, Fe)impurities are shown to introduce the necessary magnetic moment that makes ZnO good candidates for spintronic applications.

Structural and magnetic properties of Zn.sub.x./sub.Mn.sub.3-x./sub.O.sub.4./sub. spinels

Czech Academy of Sciences Publication Activity Database

Nádherný, L.; Maryško, Miroslav; Sedmidubský, D.; Martin, C.

2016-01-01

Roč. 413, Sep (2016), s. 89-96 ISSN 0304-8853 Institutional support: RVO:68378271 Keywords : Zn-Mn-O spinels * solid-state reaction * ferrimagnetic clusters * ZnO Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.630, year: 2016

Probing defect driven tunable spontaneous magnetization in paramagnetic Zn{sub 0.95}Co{sub 0.05}O epitaxial films by X-ray absorption investigations

Energy Technology Data Exchange (ETDEWEB)

Satyarthi, P.; Ghosh, S. [Nanostech Laboratory, Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India); Wang, Y.T.; Zhou, S. [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstr. 400, 01328 Dresden (Germany); Kumar, P.; Kanjilal, D. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Olivi, L. [Elettra-Sincrotrone Trieste S.C.p.A., s.s. 14 km 163.5, 34194 Basovizza Trieste (Italy); Bürger, D.; Skorupa, I.; Schmidt, H. [Department of Materials for Nanoelectronics, Chemnitz University of Technology, 09126 Chemnitz (Germany); Srivastava, P., E-mail: pankajs@physics.iitd.ac.in [Nanostech Laboratory, Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India)

2015-11-15

In order to address existing unresolved issues related to intrinsic and extrinsic origins of ferromagnetism in Zn{sub 1−x}Co{sub x}O based diluted magnetic semiconductors for varying x, the present work aims to investigate the tunable ferromagnetism triggered in paramagnetic Zn{sub 0.95}Co{sub 0.05}O films using 500 KeV inert xenon ion irradiation of different fluences. The origin of ferromagnetism in post irradiated Zn{sub 0.95}Co{sub 0.05}O films is understood from different densities of bound magnetic polarons (BMPs) formation through correlated spins of tetrahedrally substituted Co{sup 2+} ions and anionic vacancies. The alteration in crystallographic positions of Zn, Co cations, and O anions in the tetrahedral environment as analyzed from Zn and Co K-edgeX-ray absorption and O 1s photoemission is a crucial factor for the stabilization of different density of BMPs. Magnetic field and temperature dependence of X-ray magnetic circular dichroism at the Co L{sub 2,3} edge provide experimental evidence of purely paramagnetic contribution from well localized Co{sup 2+} ions of Co sublattice for paramagnetic Zn{sub 0.95}Co{sub 0.05}O film. The paramagnetic Co{sup 2+} ions of Co sublattice persist in irradiated films, which reveal BMPs formation as the origin of ferromagnetism. - Highlights: • Ferromagnetism is triggered and tuned in Zn{sub 1−x}Co{sub x}O films by inert ion irradiation. • Ferromagnetism is stabilized from different degree of bound magnetic polarons. • The alteration in crystallographic positions of Zn, Co and O atoms tunes BMPs. • Paramagnetic contribution of the Co sublattice persists in Zn{sub 1−x}Co{sub x}O films.

Influence of starting powder milling on magnetic properties of Mn-Zn ferrite

Directory of Open Access Journals (Sweden)

Miodrag M. Milutinov

2017-06-01

Full Text Available In this paper, the influence of additional sieving and milling of starting industrial Mn-Zn powders on magnetic properties was investigated. The starting powder was milled for 60 minutes, followed by sieving through 325 and 400 meshes. The starting and milled powders were used to fabricate toroid shaped samples sintered at 1200°C for 2 hours. Structural parameters of the fabricated samples were analysed by X-ray diffraction and scanning electron microscopy. Complex permeability, core loss density, and hysteresis were measured using the modified watt-meter method. The complex permeability and hysteresis loop were modelled with a new model proposed in the paper. The core loss density was modelled with the Steinmetz empirical equation. The experimental results and calculations show the significance of the additional milling and sieving process on magnetic properties of Mn-Zn ferrite in the frequency range 0.1-10MHz. These processes increase the relative permeability about 3 times and decrease the core loss 4 times by milling of the starting powder.

Synthesis, characterization and magnetic properties of MWCNTs decorated with Zn-substituted MnFe{sub 2}O{sub 4} nanoparticles using waste batteries extract

Energy Technology Data Exchange (ETDEWEB)

Gabal, M.A., E-mail: mgabalabdonada@yahoo.com [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); Al-Harthy, E.A. [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); Center of Excellence in Environmental Studies, King Abdulaziz University, PO Box 80216, Jeddah 21589 (Saudi Arabia); Al Angari, Y.M.; Abdel Salam, M.; Asiri, A.M. [Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia)

2016-06-01

Mn{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} (x=0.2–0.8) nano-crystals, synthesized from recycling of Zn–C batteries, were successfully self-assembled alongside multi-walled carbon nanotubes (MWCNTs) via an environmentally friend sucrose auto-combustion method. The effect of Zn-content on structural and magnetic properties were investigated and discussed. XRD revealed the formation of single-phase ferrites. DTA–TG experiment showed that the auto-combustion reaction finished at about 350 {sup °}C. TEM exhibited that the MWCNTs are well decorated with ferrite particles. Hysteresis loop measurements revealed ferromagnetic behavior, with saturation magnetization decrease by the addition of MWCNTs or increasing Zn-Content. The kinetics of methylene blue dye (MB) removal using MWCNTs/Mn{sub 0.8}Zn{sub 0.2}Fe{sub 2}O nano-composite was investigated and discussed. - Graphical abstract: TEM image of MWCNTs/Mn{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4} nano-composite showed that the MWCNTs were completely decorated with magnetic nanoparticles. The decoration passed through nucleation and growth processes in which nucleation of ferrite nanoparticles first takes place on the surface of MWCNTs followed by a subsequent growth of these nuclei. - Highlights: • Mn-Zn-ferrites were obtained via recycling process of spent Zn-C batteries. • Mn1−xZnxFe2O4/MWCNTS nano-composites were synthesized via sucrose combustion route. • Zn-substitution effect on structural and magnetic properties was investigated. • MWCNTs/Mn0.8Zn0.2Fe2O4 was investigated to remove MB dye from aqueous media.

Synthesis and magnetic properties study of a Nickel Cobalt Zinc Ferrite with low Zn O content

CERN Document Server

Hoor, M

2003-01-01

Attempt is made, in this work, to prepare and study the microstructure and magnetic properties of a Ni CO Zn ferrite compound with very low Zn O content of Ni sub 0 sub . sub 4 sub 6 sub 7 Zn sub 0 sub . sub 0 7 Co sub 0.015 Fe sub 0 sub . sub 5 sub 1 sub 1 O sub 4 composition. All of the samples were prepared by conventional ceramic route and the samples were sintered at 1150, 1200, 1250 and 1300 sup d eg sup C for 2 hr s. It was shown that, the higher the sintering temperature, the higher was saturation magnetisation, the measured relative permeability and the lower was H sub c of the samples. These were related to the increased sintered densities and grain size observed. Further, the highest quality factor (Q-factor) was obtained for the sample sintered at 1250 sup d eg sup C. The observed magnetic properties are assessed in relation with microstructure.

Enhancement of soft magnetic properties of La–Zn co-doped nanocrystalline Ni{sub 2}Y hexaferrite

Energy Technology Data Exchange (ETDEWEB)

Hosseinkhan Nejad, Ehsan, E-mail: ehsanhkhani66@gmail.com [Department of Material Science and Engineering, Semnan University, Semnan (Iran, Islamic Republic of); Farzin, Yousef Alizad [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 14395-553, Tehran (Iran, Islamic Republic of); Heydari, Mohammad Ali [Department of Material Science and Engineering, Azad University of Saveh, Saveh (Iran, Islamic Republic of)

2017-02-01

The La-Zn substituted nanocrystalline Sr{sub 2−x}La{sub x}Ni{sub 2}Fe{sub 12−x}Zn{sub x}O{sub 22} (with x=0.0, 0.4, 0.5, 0.6, 0.7, 0.8 and 0.9) hexaferrites were prepared using sol-gel auto-combustion method to investigate the microstructure and magnetic properties. Fourier transform infrared spectroscopy (FT-IR) spectra showed two main absorption bands at 429 and 594 cm{sup −1} corresponding to the stretching and vibration of tetrahedral and octahedral groups in S blocks. The X-ray diffraction pattern confirmed the phase formation of Y-type hexaferrite with R-3 m space group which also provided the lattice constants and crystallite sizes of each product. Furthermore, the crystallite size (D) was found to be in the range of 31.4–43.1 nm. Field emission electron microscopy (FESEM) images confirmed that the grain size was reduced from 600 to 150 nm due to the increase of dopant cations and, subsequently, caused soft magnetic properties to improve. By performing a thorough investigation on the M–H hysteresis loops, it was found that the magnetization first increased up to x=0.7 and then decreased, while coercivity monotonously decreased from 1313 to 569 Oe. This behavior can be attributed to the migration of Fe3+ ions from spin-down to spin-up, local strains, deviation of spin arrangement and strength of superexchange interactions. - Highlights: • A systematic study was done on the effect of La–Zn substitution of Ni{sub 2}Y. • The crystallite size of this ferrites is in the range of 31.4–41.3 nm. • Coercivity of synthesis samples monotonously decreased from 1313 to 569 Oe. • The magnetization and the coercivity strongly depend on La–Zn substitution. • The soft magnetic properties of ferrites improved by increasing of dopant cations.

Extinction of photoemission of Mn-Doped ZnS nanofluid in weak magnetic field

Science.gov (United States)

Vu, Anh-Tuan; Bui, Hong-Van; Pham, Van-Ben; Le, Van-Hong; Hoang, Nam-Nhat

2016-08-01

The observation of extinction of photoluminescence of Mn-doped ZnS nanofluid under applying of weak magnetic field is reported. At a constant field of 270 Gauss and above, the exponential decays of photoluminescent intensity was observed in disregard of field direction. About 50% extinction was achieved after 30 minute magnetization and a total extinction after 1 hour. The memory effect preserved for more than 2 hours at room temperature. This extinction was observed in a system with no clear ferromagnetic behavior.

Tri-functional Fe2O3-encased Ag-doped ZnO nanoframework: magnetically retrievable antimicrobial photocatalyst

Science.gov (United States)

Karunakaran, Chockalingam; Vinayagamoorthy, Pazhamalai

2016-11-01

Fe2O3-encased ZnO nanoframework was obtained by hydrothermal method and was doped with Ag through photoreduction process. Energy dispersive x-ray spectroscopy, transmission electron microscopy (TEM), high resolution TEM, selected area electron diffractometry, x-ray diffractometry and Raman spectroscopy were employed for the structural characterization of the synthesized material. While the charge transfer resistance of the prepared nanomaterial is larger than those of Fe2O3 and ZnO the coercivity of the nanocomposite is less than that of hydrothermally obtained Fe2O3 nanostructures. Although Fe2O3/Ag-ZnO exhibits weak visible light absorption its band gap energy does not differ from that of ZnO. The photoluminescence of the fabricated nanoframework is similar to that of ZnO. The radiative recombination of charge carriers is slightly slower in Fe2O3/Ag-ZnO than in ZnO. The synthesized Fe2O3-encased Ag-doped ZnO, under UV A light, exhibits sustainable photocatalytic activity to degrade dye and is magnetically recoverable. Also, the Fe2O3/Ag-ZnO nanocomposite disinfects bacteria effectively in absence of direct illumination.

Structural and magnetic Ni-Zn ferrite synthesized by combustion reaction and sintered in a conventional oven; Caracterizacao estrutural e magnetica de ferrita Ni-Zn sintetizadas por reacao de combustao e sinterizadas em forno convencional

Energy Technology Data Exchange (ETDEWEB)

Vieira, D.A.; Diniz, V.C.S.; Costa, A.C.F.M., E-mail: deboralbq@hotmail.com [Universidade Federal de Campina Grande (UFCG), Campina Grande, PB (Brazil). Departamento de Engenharia de Materiais; Kiminami, R.H.G.A. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Engenharia de Materiais; Cornejo, D.R. [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto de Fisica. Departamento de Fisica dos Materiais e Mecanica

2011-07-01

The Ni-Zn ferrite due to their electrical and magnetic properties allows use in various technological applications. These properties can be controlled through appropriate choice of chemical composition, structural characteristics and morphology of the powders used and the techniques used for sintering. Thus, this study aims to evaluate the sintering in a conventional oven at a temperature of 1200 deg C/2h samples of Ni-Zn ferrite synthesized by microwave energy. The samples were characterized by density measurement, XRD, SEM and magnetic measurements. The results indicate the phase formation of Ni-Zn ferrite crystalline phase with crystallite size of 80 nm. The sample was heterogeneous microstructure with grain size of about 1 μm high intergranular porosity. The sample showed the saturation magnetization of 7.57 emu/g, coercive field and remanent magnetization close to zero, thus indicating a behavior characteristic of superparamagnetic materials. (author)

Dicationic polymeric ionic-liquid-based magnetic material as an adsorbent for the magnetic solid-phase extraction of organophosphate pesticides and polycyclic aromatic hydrocarbons.

Science.gov (United States)

Jiang, Qiong; Liu, Qin; Chen, Qiliang; Zhao, Wenjie; Xiang, Guoqiang; He, Lijun; Jiang, Xiuming; Zhang, Shusheng

2016-08-01

Magnetic particles modified with a dicationic polymeric ionic liquid are described as a new adsorbent in magnetic solid-phase extraction. They were obtained through the copolymerization of a 1,8-di(3-vinylimidazolium)octane-based ionic liquid with vinyl-modified SiO2 @Fe3 O4 , and were characterized by FTIR spectroscopy, X-ray diffraction, and vibrating sample magnetometry. The modified magnetic particles are effective in the extraction of organophosphate pesticides and polycyclic aromatic hydrocarbons. Also, they can provide different extraction performance for the selected analytes including fenitrothion, parathion, fenthion, phoxim, phenanthrene, and fluoranthene, where the extraction efficiency is found to be in agreement with the hydrophobicity of analytes. Various factors influencing the extraction efficiency, such as, the amount of adsorbent, extraction, and desorption time, and type and volume of the desorption solvent, were optimized. Under the optimized conditions, a good linearity ranging from 1-100 μg/L is obtained for all analytes, except for parathion (2-200 μg/L), where the correlation coefficients varied from 0.9960 to 0.9998. The limits of detection are 0.2-0.8 μg/L, and intraday and interday relative standard deviations are 1.7-7.4% (n = 5) and 3.8-8.0% (n = 3), respectively. The magnetic solid-phase extraction combined with high-performance liquid chromatography can be applied for the detection of trace targets in real water samples with satisfactory relative recoveries and relative standard deviations. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of Sintering Holding Time on the Structural, Electrical and Magnetic Properties of Zn0.95Ni0.05O

Science.gov (United States)

Ginting, M.; Aryanto, D.; Kurniawan, C.; Sari, A. Y.; Subhan, A.; Sudiro, T.; Sebayang, P.; Tarigan, E. R.; Nasruddin, M. N.; Sebayang, K.

2017-05-01

Zn0.95Ni0.05O has been synthesized by mixing 5% mol of NiO into ZnO using solid state reaction and high-speed shaker mill method. The samples were sintered at 900 °C with holding time for 2, 4 and 8 hours. Crystal structure, electrical and magnetic properties of Zn0.95Ni0.05O were characterized by using XRD, I-V, C-V and VSM. XRD results showed that variation of holding time does not change the structure of ZnO and no other secondary phase observed. The value of lattice parameters (a and c) tends to decrease proportionally to the holding time. The Intensity value changes and the peak shifted to a higher 2θ angle due to holding time variation. In general, the conductance of Zn0.95Ni0.05O decreases and the magnetic properties decrease also as the holding time is increased.

Effect of oxygen vacancy induced by pulsed magnetic field on the room-temperature ferromagnetic Ni-doped ZnO synthesized by hydrothermal method

Energy Technology Data Exchange (ETDEWEB)

Zhong, Min [Shanghai University, Laboratory for Microstructures, School of Materials Science and Engineering, 149 Yanchang Road, 200072 Shanghai (China); Li, Ying, E-mail: liying62@shu.edu.cn [Shanghai University, Laboratory for Microstructures, School of Materials Science and Engineering, 149 Yanchang Road, 200072 Shanghai (China); Tariq, Muhammad; Hu, Yemin; Li, Wenxian; Zhu, Mingyuan; Jin, Hongmin [Shanghai University, Laboratory for Microstructures, School of Materials Science and Engineering, 149 Yanchang Road, 200072 Shanghai (China); Li, Yibing [School of Chemistry, The University of New South Wales, Sydney, NSW, 2052 (Australia)

2016-08-05

Room temperature ferromagnetic 2% Ni doped ZnO rods were synthesized by high pulsed magnetic field-assisted hydrothermal method. A detailed study on the effect of high pulsed magnetic field on morphology, structural and magnetic properties of the ZnO rods has been carried out systematically by varying the intensity of field from 0 to 4 T. X-ray diffraction, Energy-dispersive spectroscopy measurements, and Raman spectra analysis suggest that all the samples have hexagonal wurtzite structure without detectable impurity. Field emission scanning electron microscopy images indicate that the particle size of samples decrease with increasing intensity of field. High resolution transmission electron microscopy observation ensures that the Ni ions addition do not change the wurtzite host matrix. X-ray photoelectron spectroscopy confirms the incorporation of Ni elements as divalent state and the dominant presence of oxygen vacancies in samples fabricated under 4 T pulsed magnetic field. Hysteresis loops demonstrate that the saturation magnetization increased regularly with the mounting magnetic field. On the framework of bound magnetic polaron model, the rising content of oxygen vacancies, as donor defect, lead to the stronger ferromagnetism in samples with pulsed magnetic field. Our findings provide a new insight for tuning the defect density by precisely controlling the intensity of field in order to get the desired magnetic behavior at room temperature. - Graphical abstract: This figure shows the magnetization versus magnetic field curves for 2%Ni doped ZnO as prepared with 0, 1, 2, 3 and 4 T pulsed magnetic field at 290 K. For 0 T sample, no ferromagnetic response is observed. But all the samples synthesized with field were well-defined hysteresis loops. The saturation magnetization estimated from the hysteresis loop come out to be ∼0.0024, 0.0023, 0.0036 and 0.0061 emu/g for 1 T, 2 T, 3 T and 4 T samples, respectively. As shown in the curves, the room

The magnetic ordering in high magnetoresistance Mn-doped ZnO thin films

KAUST Repository

Venkatesh, S.

2016-03-24

We studied the nature of magnetic ordering in Mn-doped ZnO thin films that exhibited ferromagnetism at 300 K and superparamagnetism at 5 K. We directly inter-related the magnetisation and magnetoresistance by invoking the polaronpercolation theory and variable range of hopping conduction below the metal-to-insulator transition. By obtaining a qualitative agreement between these two models, we attribute the ferromagnetism to the s-d exchange-induced spin splitting that was indicated by large positive magnetoresistance (∼40 %). Low temperature superparamagnetism was attributed to the localization of carriers and non-interacting polaron clusters. This analysis can assist in understanding the presence or absence of ferromagnetism in doped/un-doped ZnO.

The magnetic ordering in high magnetoresistance Mn-doped ZnO thin films

Energy Technology Data Exchange (ETDEWEB)

Venkatesh, S.; Baras, A.; Roqan, I. S., E-mail: Iman.roqan@kaust.edu.sa [Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900 (Saudi Arabia); Lee, J.-S. [Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States)

2016-03-15

We studied the nature of magnetic ordering in Mn-doped ZnO thin films that exhibited ferromagnetism at 300 K and superparamagnetism at 5 K. We directly inter-related the magnetisation and magnetoresistance by invoking the polaron percolation theory and variable range of hopping conduction below the metal-to-insulator transition. By obtaining a qualitative agreement between these two models, we attribute the ferromagnetism to the s-d exchange-induced spin splitting that was indicated by large positive magnetoresistance (∼40 %). Low temperature superparamagnetism was attributed to the localization of carriers and non-interacting polaron clusters. This analysis can assist in understanding the presence or absence of ferromagnetism in doped/un-doped ZnO.

Structural and magnetic properties of NiZn-ferrite thin films prepared by radio frequency magnetron sputtering

International Nuclear Information System (INIS)

Liu Yingli; Li Yuanxun; Zhang Huaiwu; Chen Daming; Mu Chunhong

2011-01-01

Polycrystalline NiZn-ferrite thin films were deposited on Si(100) substrate by rf magnetron sputtering, using targets with a nominal composition of Ni 0.5 Zn 0.5 Fe 2 O 4 . The effects of substrate condition, sputtering pressure, and postannealing on the structure and magnetic properties of thin films have been investigated. Our results show that the preferred orientation of the NiZn spinel film changed from (311) to (400) with increasing the Ar pressure from 0.8 to 1.6 Pa, meanwhile, the grain size also increased. Atomic force microscopy analysis indicates that perfect surface morphology of the film can be obtained at a relatively lower sputtering pressure of 1.0 Pa. The relative percentage of residual oxygen increases significantly on a condition of lower sputtering pressure, and plays an important role in film structure due to the strong molecular adsorption tendency of oxygen on the film surface during the deposition process. A thin film with a typical thickness of 1 μm, a saturation magnetization of 150 emu/cm 3 , and a coercivity of 8.8 kA/m has been obtained after annealing at 800 deg. C, which has the potential application in magnetic integrated circuits.

Rectifying magnetic tunnel diode like behavior in Co2MnSi/ZnO/p-Si heterostructure

Science.gov (United States)

Maji, Nilay; Nath, T. K.

2018-04-01

The rectifying magnetic tunnel diode like behavior has been observed in Co2MnSi/ZnO/p-Si heterostructure. At first an ultra thin layer of ZnO has been deposited on p-Si (100) substrate with the help of pulsed laser deposition (PLD). After that a highly spin-polarized Heusler alloy Co2MnSi (CMS) film (250 nm) has been grown on ZnO/p-Si using electron beam physical vapor deposition technique. The phase purity of the sample has been confirmed through high resolution X-Ray diffraction technique. The electrical transport properties have been investigated at various isothermal conditions in the temperature range of 77-300 K. The current-voltage characteristics exhibit an excellent rectifying tunnel diode like behavior throughout the temperature regime. The current (I) across the junction has been found to decrease with the application of an external magnetic field parallel to the plane of the CMS film clearly indicating positive junction magnetoresistance (JMR) of the heterostructure. The magnetic field dependent JMR behavior of our heterostructure has been investigated in the same temperature range. Our heterostructure clearly demonstrates a giant positive JMR at 78 K (˜264%) and it starts decreasing with increasing temperature. If we compare our results with earlier reported results on other heterostructures, it can be seen that the JMR value for our heterojunction saturates at a much lower external magnetic field, thus creating it a better alternative for spin tunnel diodes in upcoming spintronics device applications.

Polymeric ionic liquid based on magnetic materials fabricated through layer-by-layer assembly as adsorbents for extraction of pesticides.

Science.gov (United States)

He, Lijun; Cui, Wenhang; Wang, Yali; Zhao, Wenjie; Xiang, Guoqiang; Jiang, Xiuming; Mao, Pu; He, Juan; Zhang, Shusheng

2017-11-03

In this study, layer-by-layer assembly of polyelectrolyte multilayer films on magnetic silica provided a convenient and controllable way to prepare polymeric ionic liquid-based magnetic adsorbents. The resulting particles were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and magnetic measurements. The data showed that the magnetic particles had more homogeneous spherical shapes with higher saturation magnetization when compared to those obtained by free radical polymerization method. This facilitated the convenient collection of magnetic particles, with higher extraction repeatability. The extraction performance of the multilayer polymeric ionic liquid-based adsorbents was evaluated by magnetic solid-phase extraction of four pesticides including quinalphos, fenthion, phoxim, and chlorpropham. The data suggested that the extraction efficiency depended on the number of layers in the film. The parameters affecting the extraction efficiency were optimized, and good linearity ranging from 2 to 250μgL -1 was obtained with correlation coefficients of 0.9994-0.9998. Moreover, the proposed method presented low limit of detection (0.5μgL -1 , S/N=3) and limit of quantification (1.5μgL -1 , S/N=10), and good repeatability expressed by the relative standard deviation (2.0%-4.6%, n=5). The extraction recoveries of four pesticides were found to range from 58.9% to 85.8%. The reliability of the proposed method was demonstrated by analyzing environmental water samples, and the results revealed satisfactory spiked recovery, relative standard deviation, and selectivity. Copyright © 2017 Elsevier B.V. All rights reserved.

Magnetic properties of Zn(P/sub x/As/sub 1-x/)2 alloys

International Nuclear Information System (INIS)

Vitkina, T.Z.; Smolyarenko, E.M.; Trukhan, V.M.

1987-01-01

The authors study the magnetic properties of Zn(P/sub x/As/sub 1-x/) 2 alloys. The concentration-dependent magnetic susceptibility of these alloys is shown, as is the temperature dependence of the magnetic susceptibility in solid solutions of the alloys. The diamagnetic susceptibility associated with the valence electrons displays a marked change for a transition to the bound state inasmuch as the valence electrons constitute the chemical bonding in the crystal. The diamagnetic component of the susceptibility of the valence electrons is calculated according to the MO LCAO approximation on the assumption that there is sp 3 -hybridization of the atomic wave function

Nanoporous gold microelectrode prepared from potential modulated electrochemical alloying–dealloying in ionic liquid

International Nuclear Information System (INIS)

Jiang, Junhua; Wang, Xinying; Zhang, Lei

2013-01-01

Highlights: • A green chemistry method for producing nanoporous gold microelectrode was studied. • An ionic liquid plating bath was utilized for electrochemical alloying–dealloying. • Nanostructures of gold surface layers can be tuned by modulating potential. • Nanoporous gold microelectrode has high surface area and merit of a microelectrode. • Nitrite oxidation and reduction on nanoporous gold microelectrode were studied. -- Abstract: Nanoporous gold (NPG) microelectrodes with high surface area and open pore network were successfully prepared by applying modulated potential to a polycrystalline Au-disk microelectrode in ionic liquid electrolyte containing ZnCl 2 at elevated temperature. During cathodic process, Zn is electrodeposited and interacted with Au microdisk substrate to form a AuZn alloy phase. During subsequent anodic process, Zn is selectively dissolved from the alloy phase, leading to the formation of a NPG layer which can grow with repetitive potential modulation. Scanning-electron microscope and energy dispersive X-ray microscope measurements show that the NPG microelectrodes possessing nanoporous structures can be tuned via potential modulation, and chemically contain a small amount of Zn whose presence has no obvious influence on electrochemical responses of the electrodes. Steady-state and cyclic voltammetric studies suggest that the NPG microelectrodes have high surface area and keep diffusional properties of a microelectrode. Electrochemical nitrite reduction and oxidation are studied as model reactions to demonstrate potential applications of the NPG microelectrodes in electrocatalysis and electroanalysis. These facts suggest that the potential-modulated electrochemical alloying/dealloying in ionic liquid electrolyte offers a convenient green-chemistry method for the preparation of nanoporous microelectrodes

Influence of particle size on the magnetic spectrum of NiCuZn ferrites for electromagnetic shielding applications

Energy Technology Data Exchange (ETDEWEB)

Wu, Xiaohan; Yan, Shuoqing; Liu, Weihu [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei (China); Feng, Zekun, E-mail: fengzekun@mail.hust.edu.cn [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei (China); Chen, Yajie; Harris, Vincent G. [Center for Microwave Magnetic Materials and Integrated Circuits, and Department of Electrical and Computer Engineering, Northeastern University, Boston, MA 02115 (United States)

2016-03-01

The effect of ferrite particle size on the magnetic spectra (1 MHz to 1 GHz) of NiCuZn polycrystalline ferrites doped with Co{sub 2}O{sub 3} and Bi{sub 2}O{sub 3} were systematically investigated. The experiments indicate that the ferrite particle size tailored by grinding time and corresponding sintering temperatures is crucial to achieving high permeability, high Q-factor and low magnetic loss, at 13.56 MHz for electromagnetic shielding applications especially in the near field communication (NFC) field. It is evident that high-performance NiZnCu ferrite materials are strongly tailored by morphology and microstructure. It is conclusive that fine ferrite particles and relatively low sintering temperatures are favorable to lowering magnetic loss and enhancing permeability. This work has built a foundation for improvement of the ferrite slurry used for fabrication of large area tape-casting ferrite sheets. - Highlights: • Fine particles are favorable to lowering magnetic loss and enhancing permeability.

Dynamic magnetization of NiZn ferrite doped FeSiAl thin films fabricated by oblique sputtering

Energy Technology Data Exchange (ETDEWEB)

Zhong, Xiaoxi, E-mail: xiaoxi.zhong@gmail.com [Sichuan Province Key Laboratory of Information Materials and Devices Application, Chengdu University of Information Technology, Chengdu 610225 (China); Phuoc, Nguyen N. [Temasek Laboratories, National University of Singapore, 5A Engineering Drive 2, Singapore 117411 (Singapore); Soh, Wee Tee [Center for Superconducting and Magnetic Materials, Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Ong, C.K. [Temasek Laboratories, National University of Singapore, 5A Engineering Drive 2, Singapore 117411 (Singapore); Center for Superconducting and Magnetic Materials, Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Li, Lezhong [Sichuan Province Key Laboratory of Information Materials and Devices Application, Chengdu University of Information Technology, Chengdu 610225 (China)

2017-06-15

Highlights: • We prepared NiZn ferrite doped FeSiAl-based thin films using oblique deposition technique. • The magnetic properties of FeSiAl-based thin films were systematically studied. • Two ferromagnetic resonance peaks were observed in the permeability spectra. • The thermal stability of microwave properties of FeSiAl-based films was studied. • The thermal stability of properties we studied was relatively good. - Abstract: In this study, we comprehensively investigate the dynamic magnetic properties of FeSiAl-NiZnFeO thin films prepared by the oblique deposition method via a shorted microstrip perturbation technique. For the films with higher oblique angle and NiZn ferrite doping amount, there are two ferromagnetic resonance peaks observed in the permeability spectra, and both of the two peaks originate from FeSiAl. Furthermore, the magnetic anisotropy field H{sub K} of the ferromagnetic resonance peak at higher frequency is enhanced with increasing doping amount, which is interpreted in terms of the contribution of reinforced stress-induced anisotropy and shape anisotropy brought about by doping elements and oblique sputtering method. In addition, the thermal stability of the ferromagnetic resonance frequency f{sub FMR} of FeSiAl-NiZnFeO films with oblique angles of 35° and 45° with respect to temperature ranging from 300 K to 420 K is deteriorated with increasing ferrite doping amount, which is mainly ascribed to the influence of pair-ordering anisotropy and/or the reduction of the FeSiAl grain size.

Effect of Zn addition on structural, magnetic properties, antistructural modeling of Co1-xZnxFe2O4 nano ferrite

Science.gov (United States)

Raghuvanshi, S.; Kane, S. N.; Tatarchuk, T. R.; Mazaleyrat, F.

2018-05-01

Effect of Zn addition on cationic distribution, structural properties, magnetic properties, antistructural modeling of nanocrystalline Co1-xZnxFe2O4 (0.08 ≤ x ≤ 0.56) ferrite is reported. XRD confirms the formation of single phase cubic spinel nano ferrites with average grain diameter ranging between 41.2 - 54.9 nm. Coercivity (Hc), anisotropy constant (K1) decreases with Zn addition, but experimental, theoretical saturation magnetization (Ms, Ms(t)) increases upto x = 0.32, then decreases, attributed to the breaking of collinear ferrimagnetic phase. Variation of magnetic properties is correlated with cationic distribution. A new antistructural modeling for describing active surface centers is discussed to explain change in concentration of donor's active centers Zn'B, Co'B, acceptor's active centers Fe*A are explained.

Effects of ageing on the electrical characteristics of Zn/ZnS/n-GaAs/In structure

Science.gov (United States)

Güzeldir, B.; Sağlam, M.

2016-04-01

Zn/ZnS/n-GaAs/In structure has been fabricated by the Successive Ionic Layer Adsorption and Reaction (SILAR) method and the influence of the time dependent or ageing on the characteristic parameters are examined. The current-voltage (I-V) of the structure have been measured immediately, 1, 3, 5, 15, 30, 45, 60, 75, 90, 105, 120, 135, 150 and 165 days after fabrication of this structure. The characteristics parameters of this structure such as barrier height, ideality factor, series resistance are calculated from the I-V measurements. It has been seen that the changes of characteristic parameters such as barrier height, ideality factor and series resistance of Zn/ZnS/n-GaAs/In structure have lightly changed with increasing ageing time.

Leaching of nano-ZnO in municipal solid waste

Energy Technology Data Exchange (ETDEWEB)

Sakallioglu, T.; Bakirdoven, M.; Temizel, I. [Institute of Environmental Sciences, Bogazici University, 34342 Istanbul (Turkey); Demirel, B., E-mail: burak.demirel@boun.edu.tr [Institute of Environmental Sciences, Bogazici University, 34342 Istanbul (Turkey); Copty, N.K.; Onay, T.T.; Uyguner Demirel, C.S. [Institute of Environmental Sciences, Bogazici University, 34342 Istanbul (Turkey); Karanfil, T. [Environmental Engineering and Earth Science, Clemson University, Clemson, SC 29634 (United States)

2016-11-05

Highlights: • Leaching potential of 3 different types of nano-ZnO in real fresh MSW was investigated. • Batch tests were conducted at different pH, ionic strength and ZnO concentrations. • Most of the added nano-ZnO mass was retained within the solid waste matrix. • The pH and IS conditions did not significantly influence the leaching behavior of ZnO. • A kinetic particle deposition/detachment model was developed to analyze ZnO behavior. - Abstract: Despite widespread use of engineered nanomaterials (ENMs) in commercial products and their potential disposal in landfills, the fate of ENMs in solid waste environments are still not well understood. In this study, the leaching behavior of nano ZnO -one of the most used ENMs- in fresh municipal solid waste (MSW) was investigated. Batch reactors containing municipal solid waste samples were spiked with three different types of nano ZnO having different surface stabilization. The leaching of ZnO was examined under acidic, basic and elevated ionic strength (IS) conditions. The results of the 3-day batch tests showed that the percent of the added nano-ZnO mass retained within the solid waste matrix ranged between 80% and 93% on average for the three types of nano-ZnO tested. The pH and IS conditions did not significantly influence the leaching behavior of ZnO. To further analyze the behavior of ZnO in the MSW matrix, a kinetic particle deposition/detachment model was developed. The model was able to reproduce the main trends of the batch experiments. Reaction rate constants for the batch tests ranged from 0.01 to 0.4 1/hr, reflecting the rapid deposition of nano-ZnO within the MSW matrix.

A novel magnetic core-shell nanocomposite Fe3O4@chitosan@ZnO for the green synthesis of 2-benzimidazoles

Science.gov (United States)

Tian, Fei; Niu, Libo; Chen, Bo; Gao, Xuejia; Lan, Xingwang; Huo, Li; Bai, Guoyi

2017-10-01

A novel magnetic core-shell nanocomposite Fe3O4@Chitosan@ZnO was successfully prepared by in situ chemical precipitation method. It has a clear core-shell structure with magnetic Fe3O4 (about 160 nm in diameter) as core, chitosan as the inner shell, and ZnO as the outer shell, as demonstrated by the transmission electron microscopy and the related elemental mapping. Moreover, this nanocomposite has high magnetization (43.6 emu g-1) so that it can be easily separated from the reaction mixture within 4 s by an external magnetic field. The introduction of the natural chitosan shell, instead of the conventional SiO2 shell, and its combination with the active ZnO ensures this novel nanocomposite green character and good catalytic performance in the synthesis of 2-benzimidazoles with moderate to excellent isolated yields at room temperature. Notably, it can be recycled seven times without appreciable loss of its initial catalytic activity, demonstrating its good stability and making it an attractive candidate for the green synthesis of 2-benzimidazoles. [Figure not available: see fulltext.

Magnetic and bioactivity evaluation of ferrimagnetic ZnFe 2O 4 containing glass ceramics for the hyperthermia treatment of cancer

Science.gov (United States)

Shah, Saqlain A.; Hashmi, M. U.; Alam, S.; Shamim, A.

2010-02-01

Glass ceramics of the composition xZnO·25Fe 2O 3·(40- x)SiO 2·25CaO·7P 2O 5·3Na 2O were prepared by the melt-quench method using oxy-acetylene flame. Glass-powder compacts were sintered at 1100 °C for 3 h and then rapidly cooled at -10 °C. X-ray diffraction (XRD) revealed 3 prominent crystalline phases: ZnFe 2O 4, CaSiO 3 and Ca 10(PO 4) 6(OH) 2. Vibrating sample magnetometer (VSM) data at 10 KOe and 500 Oe showed that saturation magnetization, coercivity and hence hysteresis area increased with the increase in ZnO content. Nano-sized ZnFe 2O 4 crystallites were of pseudo-single domain structure and thus coercivity increased with the increase in crystallite size. ZnFe 2O 4 exhibited ferrimagnetism due to the random distribution of Zn 2+ and Fe 3+ cations at tetrahedral A sites and octahedral B sites. This inversion/random distribution of cations was probably due to the surface effects of nano-ZnFe 2O 4 and rapid cooling of the material from 1100 °C (thus preserving the high temperature state of the random distribution of cations). Calorimetric measurements were carried out using magnetic induction furnace at 500 Oe magnetic field and 400 KHz frequency. The data showed that maximum specific power loss and temperature increase after 2 min were 26 W/g and 37 °C, respectively for the sample containing 10% ZnO. The samples were immersed in simulated body fluid (SBF) for 3 weeks. Scanning electron microscope (SEM), energy dispersive spectroscopy (EDX) and XRD results confirmed the growth of precipitated hydroxyapatite phase after immersion in SBF, suggesting that the ferrimagnetic glass ceramics were bioactive and could bond to the living tissues in physiological environment.

Magnetic and bioactivity evaluation of ferrimagnetic ZnFe2O4 containing glass ceramics for the hyperthermia treatment of cancer

International Nuclear Information System (INIS)

Shah, Saqlain A.; Hashmi, M.U.; Alam, S.; Shamim, A.

2010-01-01

Glass ceramics of the composition xZnO.25Fe 2 O 3 .(40-x)SiO 2 .25CaO.7P 2 O 5 .3Na 2 O were prepared by the melt-quench method using oxy-acetylene flame. Glass-powder compacts were sintered at 1100 deg. C for 3 h and then rapidly cooled at -10 deg. C. X-ray diffraction (XRD) revealed 3 prominent crystalline phases: ZnFe 2 O 4 , CaSiO 3 and Ca 10 (PO 4 ) 6 (OH) 2 . Vibrating sample magnetometer (VSM) data at 10 KOe and 500 Oe showed that saturation magnetization, coercivity and hence hysteresis area increased with the increase in ZnO content. Nano-sized ZnFe 2 O 4 crystallites were of pseudo-single domain structure and thus coercivity increased with the increase in crystallite size. ZnFe 2 O 4 exhibited ferrimagnetism due to the random distribution of Zn 2+ and Fe 3+ cations at tetrahedral A sites and octahedral B sites. This inversion/random distribution of cations was probably due to the surface effects of nano-ZnFe 2 O 4 and rapid cooling of the material from 1100 deg. C (thus preserving the high temperature state of the random distribution of cations). Calorimetric measurements were carried out using magnetic induction furnace at 500 Oe magnetic field and 400 KHz frequency. The data showed that maximum specific power loss and temperature increase after 2 min were 26 W/g and 37 deg. C, respectively for the sample containing 10% ZnO. The samples were immersed in simulated body fluid (SBF) for 3 weeks. Scanning electron microscope (SEM), energy dispersive spectroscopy (EDX) and XRD results confirmed the growth of precipitated hydroxyapatite phase after immersion in SBF, suggesting that the ferrimagnetic glass ceramics were bioactive and could bond to the living tissues in physiological environment.

Structural and magnetic properties in Mn-doped ZnO films prepared by pulsed-laser deposition

International Nuclear Information System (INIS)

Li, Qiang; Wang, Yuyin; Liu, Jiandang; Kong, Wei; Ye, Bangjiao

2014-01-01

We investigated the structural and magnetic properties of Zn 0.95 Mn 0.05 O films prepared on sapphire substrates by pulsed-laser deposition. Only low temperature ferromagnetism (Curie temperature lower than 50 K) was observed in Mn-doped samples, while pure ZnO film shows a typical paramagnetic behavior. Structural analyses indicate that the substitutional Mn 2+ ions play a significant role for the low temperature ferromagnetism. Lattice defects such as V O and V Zn were not proven to be effective factors for the origin of ferromagnetism in the films. The low temperature ferromagnetism might be interpreted as p–d hybridization from indirect coupling of Mn ions (Mn–O–Mn).

Effect of calcination temperature on the structural, optical and magnetic properties of pure and Fe-doped ZnO nanoparticles

Directory of Open Access Journals (Sweden)

Pal Singh Raminder Preet

2016-06-01

Full Text Available In the present study, pure ZnO and Fe-doped ZnO (Zn0.97Fe0.03O nanoparticles were synthesized by simple coprecipitation method with zinc acetate, ferric nitrate and sodium hydroxide precursors. Pure ZnO and Fe-doped ZnO were further calcined at 450 °C, 600 °C and 750 °C for 2 h. The structural, morphological and optical properties of the samples were characterized by X-ray diffractometer (XRD, scanning electron microscope (SEM, energy dispersive spectroscopy (EDS and UV-Vis absorption spectroscopy. The X-ray diffraction studies revealed that the as-synthesized pure and doped ZnO nanoparticles have hexagonal wurtzite structure. The average crystallite size was calculated using Debye-Scherrer’s formula. The particle size was found to be in nano range and increased with an increase in calcination temperature. SEM micrographs confirmed the formation of spherical nanoparticles. Elemental compositions of various elements in pure and doped ZnO nanoparticles were determined by EDX spectroscopy. UV-Vis absorption spectra showed red shift (decrease in band gap with increasing calcination temperature. Effect of calcination on the magnetic properties of Fe-doped ZnO sample was also studied using vibrating sample magnetometer (VSM. M-H curves at room temperature revealed that coercivity and remanent polarization increase with an increase in calcination temperature from 450 °C to 750 °C, whereas reverse effect was observed for magnetization saturation.

Magnetic ionic liquids as non-conventional extraction solvents for the determination of polycyclic aromatic hydrocarbons.

Science.gov (United States)

Trujillo-Rodríguez, María J; Nacham, Omprakash; Clark, Kevin D; Pino, Verónica; Anderson, Jared L; Ayala, Juan H; Afonso, Ana M

2016-08-31

This work describes the applicability of magnetic ionic liquids (MILs) in the analytical determination of a group of heavy polycyclic aromatic hydrocarbons. Three different MILs, namely, benzyltrioctylammonium bromotrichloroferrate (III) (MIL A), methoxybenzyltrioctylammonium bromotrichloroferrate (III) (MIL B), and 1,12-di(3-benzylbenzimidazolium) dodecane bis[(trifluoromethyl)sulfonyl)]imide bromotrichloroferrate (III) (MIL C), were designed to exhibit hydrophobic properties, and their performance examined in a microextraction method for hydrophobic analytes. The magnet-assisted approach with these MILs was performed in combination with high performance liquid chromatography and fluorescence detection. The study of the extraction performance showed that MIL A was the most suitable solvent for the extraction of polycyclic aromatic hydrocarbons and under optimum conditions the fast extraction step required ∼20 μL of MIL A for 10 mL of aqueous sample, 24 mmol L(-1) NaOH, high ionic strength content of NaCl (25% (w/v)), 500 μL of acetone as dispersive solvent, and 5 min of vortex. The desorption step required the aid of an external magnetic field with a strong NdFeB magnet (the separation requires few seconds), two back-extraction steps for polycyclic aromatic hydrocarbons retained in the MIL droplet with n-hexane, evaporation and reconstitution with acetonitrile. The overall method presented limits of detection down to 5 ng L(-1), relative recoveries ranging from 91.5 to 119%, and inter-day reproducibility values (expressed as relative standard derivation) lower than 16.4% for a spiked level of 0.4 μg L(-1) (n = 9). The method was also applied for the analysis of real samples, including tap water, wastewater, and tea infusion. Copyright © 2016 Elsevier B.V. All rights reserved.

Optical and Magnetic Resonance Studies of Na-Diffused ZnO Bulk Single Crystals

Science.gov (United States)

Glaser, E. R.; Garces, N. Y.; Parmar, N. S.; Lynn, K. G.

2013-03-01

Photoluminescence (PL) and optically-detected magnetic resonance (ODMR) at 24 GHz were performed on bulk ZnO crystals after diffusion of Na impurities that were explored as an alternate doping source for p-type conductivity. PL at 2K revealed strong bandedge excitonic recombination at 3.361 eV and a broad ``orange'' PL band at 2.17 eV with FWHM of ~0.5 eV. This ``orange'' emission is very similar to that reported previously[1] from thermoluminescence measurements of intentionally Na-doped bulk ZnO and, thus, strongly suggests the incorporation and activation of the Na-diffused impurities. ODMR performed on this ``orange'' PL revealed two signals. The first was a sharp feature with g-value of ~1.96 and is a well-known ``fingerprint'' of shallow donors in ZnO. The second signal consisted of a pair of lines with an intensity ratio of ~3:1 and with g-tensors (g∥,g⊥ ~2.008-2.029) very similar to ESR signals attributed previously[2] to holes bound to Na impurities located at the axial and non-axial Zn host lattice sites in Na-doped ZnO. Thus, the ``orange'' PL can be tentatively assigned to radiative recombination between residual shallow donors and deep Na-related hole traps.

First report on synthesis of ZnFe_2O_4 thin film using successive ionic layer adsorption and reaction: Approach towards solid-state symmetric supercapacitor device

International Nuclear Information System (INIS)

Raut, Shrikant S.; Sankapal, Babasaheb R.

2016-01-01

Highlights: • First report on synthesis of ZnFe_2O_4 thin film using SILAR method. • ZnFe_2O_4 electrode yields the specific capacitance of 471 Fg"−"1 at a scan rate of 5 mV s"−"1 in 1 M NaOH aqueous solution. • Solid-state symmetric supercapacitor device based on ZnFe_2O_4 sandwiched in polyvinyl alcohol (PVA)–LiClO_4 gel electrolyte exhibits voltage windows of 1.0 V. • ZnFe_2O_4-SSS supercapacitor device shows good energy and power density with long cycle life. - Abstract: ZnFe_2O_4 thin film has been synthesized by a simple and low cost successive ionic layer adsorption and reaction (SILAR) method without the use of surfactant or template. The nanoplate composed of nanoparticles with porous surface morphology has been revealed which is beneficial towards supercapacitor application. Formed ZnFe_2O_4 thin film has been tested as an electrode material for supercapacitor through electrochemical analysis. First attempt for SILAR synthesized ZnFe_2O_4 thin film exhibited a specific capacitance of 471 Fg"−"1 at a scan rate of 5 mVs"−"1 in 1 M NaOH aqueous solution. Further, ZnFe_2O_4 solid-state symmetric (SSS) supercapacitor device demonstrated voltage window of 1.0 V with specific capacitance of 32 Fg"−"1, energy density of 4.47 Whkg"−"1 and power density of 277 Wkg"−"1 at 1 Ag"−"1 current density. Such high performance capacitive behavior indicates ZnFe_2O_4 thin film is promising and low cost electrode material towards energy storage devices for various portable electronic systems.

Magnetic nanoparticles of NiCuZn tested in different conditions in catalysis for biodiesel; Nanoparticulas magneticas de NiCuZn testadas em diferentes condicoes na catalise para biodiesel

Energy Technology Data Exchange (ETDEWEB)

Dantas, J.; Silva, F.N.; Silva, A.S.; Pereira, K.R.O.; Costa, A.C.F.M., E-mail: joeldadantas@yahoo.com.br [Universidade Federal de Campina Grande (LabSMaC/UFCG), PB (Brazil). Laboratorio de Sintese de Materiais Ceramicos

2014-07-01

In this work it was used magnetic nanoparticles Ni{sub 0,2}Cu{sub 0,3}Zn{sub 0,5}Fe{sub 2}O{sub 4}, chemical and thermally stable, under different conditions in catalysis for biodiesel. The magnetic characteristic of such material allows the catalyst recovery after the reactions by applying a permanent magnet. It was proposed to evaluate the performance of the nanomagnetic catalyst Ni{sub 0,2}Cu{sub 0,3}Zn{sub 0,5}Fe{sub 2}O{sub 4} in the transesterification, modifying the processing variables (temperature, time, molar ratio of oil:alcohol and catalyst amount). The nanoparticles were synthesized by combustion reaction and characterized by XRD, TG, BET, magnetic measurements and gas chromatography. The results revealed the formation of inverse spinel phase, type B(AB){sub 2}O{sub 4}, presenting isotherm profile classified as type V, with hysteresis loop of type 3 (H3). The magnetic hysteresis curve showed a characteristic behavior of soft magnetic material. GC analysis confirmed that nanoparticles were catalytically active, since they were superior to the reaction conducted without the catalyst presence. Besides, the reactions suffered considerable influence due to the changes of the independent variables. (author)

Successive ionic layer adsorption and reaction deposited kesterite Cu2ZnSnS4 nanoflakes counter electrodes for efficient dye-sensitized solar cells

International Nuclear Information System (INIS)

Mali, Sawanta S.; Shim, Chang Su; Hong, Chang Kook

2014-01-01

Highlights: • Cu 2 ZnSnS 4 nanoflakes by SILAR technique. • Hydrothermal synthesis of TiO 2 . • Counter electrode for DSSC application. • 4.48% conversion efficiency. - Abstract: In this investigation, we have successfully synthesized Cu 2 ZnSnS 4 (CZTS) nanoflakes by successive ionic layer adsorption and reaction (SILAR) method and used as a counter electrode in the hydrothermally grown TiO 2 based dye sensitized solar cells (DSSCs). The prepared CZTS nanoflakes were characterized using X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), micro Raman spectroscopy and energy dispersive analysis. Our DSSCs results revealed that, compared with conventional Pt/FTO counter electrode DSSCs, nanoflakes of p-type CZTS as the photocathode and n-type TiO 2 thin films as the photoanode shows an increased short circuit current (13.35 mA/cm 2 ) with 4.84% power conversion efficiency. The detailed interface properties of were analyzed by electrochemical impedance spectroscopy (EIS) measurements

Investigation of structural, surface morphological, optical properties and first-principles study on electronic and magnetic properties of (Ce, Fe)-co doped ZnO

International Nuclear Information System (INIS)

Arul Mary, J.; Judith Vijaya, J.; Bououdina, M.; John Kennedy, L.; Daie, J.H.; Song, Y.

2015-01-01

We report on the synthesis of ((Zn 1−2x Ce x Fe x ) O (x=0.00, 0.01, 0.02, 0.03, 0.04 and 0.05)) nanoparticles via microwave combustion by using urea as a fuel. To understand how the dopant influenced the structural, magnetic and optical properties of nanoparticles, it was characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectra and vibrating sample magnetometer (VSM). The stability and magnetic properties of Ce and Fe co-doped ZnO were probed by first principle calculations. From the analysis of X-ray diffraction, the samples are identified with the wurtzite crystal structure. The change in lattice parameters, micro-strain, and a small shift in XRD peaks confirms the substitution of co dopants into the ZnO lattice. Morphological investigation of the products revealed the existence of irregular shapes, such as spherical, spherodial and hexagonal. DRS measurements showed a decrease in the energy gap with increasing dopants contents, probably due to an increase in the lattice parameters. PL spectra consist of visible emission, due to the electronic defects, which are related to deep level emissions, such as oxide antisite (O Zn ), interstitial zinc (Zn i ), interstitial oxygen (O i ) and zinc vacancy (V Zn ). Magnetic measurements showed a ferromagnetic behavior for all the doped samples at room temperature. The first principle calculation results showed that the Ce governs the stability, while the Fe adjusts the magnetic characteristics in the Ce and Fe co-doped ZnO

Enhanced magnetic domain relaxation frequency and low power losses in Zn{sup 2+} substituted manganese ferrites potential for high frequency applications

Energy Technology Data Exchange (ETDEWEB)

Praveena, K., E-mail: praveenaou@gmail.com [Department of Physics, National Taiwan Normal University, Taipei, 11677, Taiwan (China); Chen, Hsiao-Wen [Department of Physics, National Taiwan Normal University, Taipei, 11677, Taiwan (China); Liu, Hsiang-Lin, E-mail: hliu@ntnu.edu.tw [Department of Physics, National Taiwan Normal University, Taipei, 11677, Taiwan (China); Sadhana, K., E-mail: sadhana@osmania.ac.in [Department of Physics, Osmania University, Saifabad, Hyderabad, 500004 (India); Murthy, S.R. [Department of Physics, Osmania University, Hyderabad, 500007 (India)

2016-12-15

Nowadays electronic industries prerequisites magnetic materials, i.e., iron rich materials and their magnetic alloys. However, with the advent of high frequency applications, the standard techniques of reducing eddy current losses, using iron cores, were no longer efficient or cost effective. Current market trends of the switched mode power supplies industries required even low energy losses in power conversion with maintenance of adequate initial permeability. From the above point of view, in the present study we aimed at the production of Manganese–Zinc ferrites prepared via solution combustion method using mixture of fuels and achieved low loss, high saturation magnetization, high permeability, and high magnetic domain relaxation frequency. The as-synthesized Zn{sup 2+} substituted MnFe{sub 2}O{sub 4} were characterized by X-ray diffractometer (XRD) and transmission electron microscopy (TEM). The fractions of Mn{sup 2+}, Zn{sup 2+} and Fe{sup 2+} cations occupying tetrahedral sites along with Fe occupying octahedral sites within the unit cell of all ferrite samples were estimated by Raman scattering spectroscopy. The magnetic domain relaxation was investigated by inductance spectroscopy (IS) and the observed magnetic domain relaxation frequency (f{sub r}) was increased with the increase in grain size. The real and imaginary part of permeability (μ′ and μ″) increased with frequency and showed a maximum above 100 MHz. This can be explained on the basis of spin rotation and domain wall motion. The saturation magnetization (M{sub s}), remnant magnetization (M{sub r}) and magneton number (µ{sub B}) decreased gradually with increasing Zn{sup 2+} concentration. The decrease in the saturation magnetization was discussed with Yafet–Kittel (Y–K) model. The Zn{sup 2+} concentration increases the relative number of ferric ions on the A sites, reduces the A–B interactions. The frequency dependent total power losses decreased as the zinc concentration increased

Super ionic conductive glass

Science.gov (United States)

Susman, S.; Volin, K.J.

Described is an ionically conducting glass for use as a solid electrolyte in a power or secondary cell containing an alkali metal-containing anode and a cathode separated by an alkali metal ion conducting glass having an ionic transference number of unity and the general formula: A/sub 1 + x/D/sub 2-x/3/Si/sub x/P/sub 3 - x/O/sub 12 - 2x/3/, wherein A is a network modifier for the glass and is an alkali metal of the anode, D is an intermediate for the glass and is selected from the class consisting of Zr, Ti, Ge, Al, Sb, Be, and Zn and X is in the range of from 2.25 to 3.0. Of the alkali metals, Na and Li are preferred and of the intermediate, Zr, Ti and Ge are preferred.

Theoretical investigation of electronic, magnetic and optical properties of ZnSe doped TM and co-doped with MnTM (TM: Fe, Cr, Co): AB-initio study

Energy Technology Data Exchange (ETDEWEB)

Behloul, M. [LMPHE (URAC 12), Departement of Physique, B.P. 1014, Faculty of Science, University Mohammed V, Rabat (Morocco); Salmani, E., E-mail: elmehdisalmani@gmail.com [LMPHE (URAC 12), Departement of Physique, B.P. 1014, Faculty of Science, University Mohammed V, Rabat (Morocco); Ez-Zahraouy, H. [LMPHE (URAC 12), Departement of Physique, B.P. 1014, Faculty of Science, University Mohammed V, Rabat (Morocco); Benyoussef, A. [LMPHE (URAC 12), Departement of Physique, B.P. 1014, Faculty of Science, University Mohammed V, Rabat (Morocco); The Institute for Nanomaterials and Nanotechnology, MAScIR (Moroccan Fondation for Advanced Science, Innovation and Research), Rabat (Morocco)

2016-12-01

Based upon the first principal spin density functional calculation, the electronic, magnetic and optical properties of ZnTMSe and ZnMnTMSe where TM=Fe, Cr, Co are studied using the Korringa-Kohn-Rostoker coherent potential approximation (KKR-CPA) method within the local density (LDA)and the self-interaction-corrected(SIC) approximation. The purpose of this study is to determine the effect of different type of dopant and concentration on ferromagnetic and half metallic behavior of ZnSe. Therefore the magnetic disorder local moment (DLM) and the ferromagnetic state are investigated for different concentrations of Mn, Fe, Cr and Co; also the advantages of co-doped ZnSe with TM elements, behavior at room temperature are discussed. The electronic structure and optical properties are studied employing the local density (LDA) and the self-interaction-corrected (SIC) approximation. Moreover, the X-ray spectra modeling are in good agreement with the electronic and magnetic properties results. - Highlights: • The magnetic properties of ZnSe codoped with MnY(Y: Fe, Cr, Co) has been investigated. • The half-metallic appears in ZnSe codoped with impurities at low concentration. • The advantages of codoped ZnSe with impurities at room temperature are discussed.

Structural, electrical and magnetic characterization of in-situ crystallized ZnO:Co thin films synthesized by reactive magnetron sputtering

Energy Technology Data Exchange (ETDEWEB)

Lardjane, Soumia, E-mail: lardjanesoumia@yahoo.fr [IRTES-LERMPS, UTBM, Site de Montbéliard, 90010 Belfort Cedex (France); Division Etude et Prédiction des Matériaux, Unité de Recherche Matériaux et Energies Renouvelables, Université Abou Bekr Belkaid, Tlemcen (Algeria); Pour Yazdi, Mohammad Arab [IRTES-LERMPS, UTBM, Site de Montbéliard, 90010 Belfort Cedex (France); Martin, Nicolas [FEMTO-ST, Département MN2S, UMR 6174 CNRS, Université de Franche-Comté, ENSMM, UTBM, 32, Avenue de l’Observatoire, 25044 Besancon Cedex (France); Bellouard, Christine [Laboratoire de Physique des Matériaux, Nancy University, CNRS, 54506 Vandoeuvre-lès-Nancy Cedex (France); Fenineche, Nour-eddine [IRTES-LERMPS, UTBM, Site de Montbéliard, 90010 Belfort Cedex (France); Schuler, Andreas [Solar Energy and Buildings Physics Laboratory, EPFL ENAC IIC LESO-PB, Station 18, Bâtiment LE, 1015 Lausanne (Switzerland); Merad, Ghouti [Division Etude et Prédiction des Matériaux, Unité de Recherche Matériaux et Energies Renouvelables, Université Abou Bekr Belkaid, Tlemcen (Algeria); Billard, Alain [IRTES-LERMPS, UTBM, Site de Montbéliard, 90010 Belfort Cedex (France)

2015-07-01

Zn{sub 1−x}Co{sub x}O (0 < x < 0.146) conductive thin films have been deposited by reactive magnetron sputtering of metallic Zn and Co targets at high pressure and temperature. The structural properties have been investigated by using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It has been observed that all as-deposited films are crystallized in pure hcp ZnO structure and neither traces of metallic nor oxide Co-rich clusters were detected. The average grain size estimated from full width at half maximum of XRD results varied between 65 and 83 nm. XPS analyses exhibit that Co ions are successfully entered into ZnO lattice as Co{sup +2}. The electrical properties including conductivity, carrier density and carrier mobility were determined by Hall effect measurements in a temperature range from 300 K to 475 K. The conductivity of the films decreases from σ{sub 300K} = 2.2 × 10{sup 4} to 2.3 × 10{sup −1} Sm{sup −1} as the Co content changes from 0 to 0.146. Magnetic measurements reveal the absence of ferromagnetism even at 3 K and a paramagnetic Curie–Weiss behavior associated to magnetic clusters. - Highlights: • Zn{sub 1−x}Co{sub x}O conductive thin films were synthesized by reactive magnetron sputtering. • Structural characterization exhibited the absence of Co clusters or secondary phases. • The film conductivity decreased with increasing of Co concentration. • No ferromagnetism was observed in all Co doped ZnO samples. • Magnetic properties are described by a Curie–Weiss behavior associated to clusters.

Influence of cold isostatic pressing on the magnetic properties of Ni-Zn-Cu ferrite

Science.gov (United States)

Le, Trong Trung; Valdez-Nava, Zarel; Lebey, Thierry; Mazaleyrat, Frédéric

2018-04-01

In power electronics, there is the need to develop solutions to increase the power density of converters. Interleaved multicellular transformers allow interleaving many switching cells and, as a result, a possible increase in the power density. This converter is often composed of a magnetic core having the function of an intercell transformer (ICT) and, depending on the complexity of the designed architecture, its shape could be extremely complex. The switching frequencies (1-10 MHz) for the new wide band gap semiconductors (SiC, GaN) allow to interleave switching cell at higher frequencies than silicon-based semiconductors (materials, but their limit in frequency drive raises the need of higher frequency magnetic materials, such Ni-Zn ferrites. These materials can operate in medium and high power converters up to 10 MHz. We propose to use Ni0,30Zn0,57Cu0,15Fe2O4 ferrite and to compress it by cold isostatic pressing (CIP) into a a green ceramic block and to machine it to obtain the desired ICT of complex shape prior sintering. We compare the magnetic permeability spectra and hysteresis loops the CIP and uniaxially pressed ferrites. The effect of temperature and sintering time as well as high-pressure on properties will be presented in detail. The magnetic properties of the sintered cores are strongly dependent on the microstructure obtained.

Structural characterization, morphology and magnetic ferrite Ni_0_,_4Zn_0_,_5Fe_2Cu_0_,_1O_4

International Nuclear Information System (INIS)

Santos, P.T.A.; Fernandes, P.C.; Santos, P.T.A.; Costa, A.C.F.M.

2011-01-01

In this work the system Ni_0_,_4Zn_0_,_5Fe_2Cu_0_,_1O_4 was obtained by combustion reaction using urea as fuel in order to evaluate their structural characteristics, and morphological imaging. The resulting samples were characterized by XRD, BET, SEM / EDS and magnetic measurements. The synthesis by combustion reaction was effective for producing samples of ferrites with crystallite size 13 nm. The X-ray diffraction showed the major phase of the inverse spinel and traces of ZnO second phase. The resulting morphology showed the formation of soft agglomerates with interparticle porosity, and mapping by SEM / EDS indicated a good distribution of elements Ni, Cu, Zn, Fe and O constituent of ferrite. The ferrite showed superparamagnetic behavior with a value of saturation magnetization of 5.60 emu / g. (author)

Effects of pH and ionic strength on the thermodynamics of human serum albumin-photosensitizer binding

International Nuclear Information System (INIS)

Jones, Cecil L.; Dickson, TiReJe; Hayes, Ronald; Thomas, Lana

2012-01-01

Highlights: ► The pH dependence of entropy and enthalpy changes was determined for zinc phthalocyanine tetrasulfonic acid, ZnPcS 4 binding to human serum albumin, HSA. ► The ionic strength dependence of entropy and enthalpy changes was determined for ZnPcS 4 acid binding to HSA. ► The primary driving force governing the interaction between ZnPcS 4 and HSA over the range of pH and ionic strength was solution dynamics. ► The interplay between entropy and enthalpy changes was demonstrated. - Abstract: Fluorescence spectroscopy was used to measure the effects of pH and ionic strength on thermodynamic parameters governing the interaction of human serum albumin with zinc phthalocyanine tetrasulfonic acid. Fluorescence emission of zinc phthalocyanine increases at 686 nm with increasing concentrations of the protein. The non-linear correlation between protein concentration and emission of the photosensitizer was fitted using Chipman's analysis to calculate the binding affinities. The standard enthalpy and entropy changes were estimated from van’t Hoff analysis of data that were acquired from temperature ramping studies. Results show that reaction is primarily driven by solution dynamics and that the change in enthalpy for the system becomes increasingly unfavorable with increasing pH and ionic strength. The effect of ionic strength on the entropy change for binding is shown to be significantly greater than the effects of pH. The interplay between entropy and enthalpy changes is demonstrated.

Overview of the phase diagram of ionic magnetic colloidal dispersions

International Nuclear Information System (INIS)

Cousin, F.; Dubois, E.; Cabuil, V.; Boue, F.; Perzynski, R.

2001-01-01

We study ionic magnetic colloidal dispersions, which are constituted of γ-Fe 2 O 3 nanoparticles dispersed in water, and stabilized with electrostatic interparticle repulsion. The phase diagram PV versus Φ (P: osmotic pressure, V: particle volume, Φ: particle volume fraction) is explored, especially in the range of high Π and high Φ. The osmotic pressure P of the colloidal dispersion is known either by a measurement either because it is imposed during the sample preparation by osmotic compression. The structure of the colloidal dispersion is determined from Small Angle Neutron Scattering. Two regimes can be distinguished. At high pressure, fluid and solid phases can exist. Their structure is governed by strong electrostatic repulsion, the range of which is here evaluated. At low pressure, gas, liquid and glassy solids can exist. Their structure results from a sticky hard sphere potential. (author)

First-principle study on magnetic properties of Mn/Fe codoped ZnS

Energy Technology Data Exchange (ETDEWEB)

Chen Hongxia, E-mail: chenhongxia1@sina.com [College of Physical Science and Electronic Techniques, Yancheng Teachers University, Yancheng 224002 (China); Department of Physics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

2012-07-15

We studied the magnetic properties of Mn/Fe codoped ZnS comparatively with and without defects using first-principle calculation. The calculated results indicate that the Mn/Fe codoped ZnS system tends to stabilize in a ferrimagnetic (FiM) configuration. To obtain a ferromagnetic (FM) configuration, we consider the doped system with defects, such as S or Zn vacancy. The calculated results indicate that the doped system with Zn vacancy favors FiM states. Although the FM states of the doped system with S vacancy are more stable than the FiM states in negative charge states, the FM states are not stable enough to exist. Finally, we replaced an S atom by a C atom in the doped system. The C atom prefers to substitute the S atom connecting Mn and Fe atoms. The formation energy of this defect is -0.40 eV, showing that Mn/Fe/C codoped ZnS can be fabricated easily by experiments. Furthermore, the FM state was lower in energy than the FiM state by 114 meV. Such a large energy difference between the FM and FiM states implies that room temperature ferromagnetism could be expected in such a system. - Highlights: Black-Right-Pointing-Pointer Mn/Fe codoped ZnS system tends to stabilize in a ferrimagnetic configuration with or without defects. Black-Right-Pointing-Pointer By additional C codoping, the doped system tends to stabilize in a ferromagnetic configuration. Black-Right-Pointing-Pointer Energy difference between ferrimagnetic and ferromagnetic states is 114 meV. Black-Right-Pointing-Pointer This indicates room temperature ferromagnetism can be likely in such a system.

Novel multifunctional NiFe{sub 2}O{sub 4}/ZnO hybrids for dye removal by adsorption, photocatalysis and magnetic separation

Energy Technology Data Exchange (ETDEWEB)

Zhu, Hua-Yue [Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, Taizhou University, Taizhou, Zhejiang 318000 (China); Department of Environmental Engineering, Taizhou University, Taizhou, Zhejiang 318000 (China); Jiang, Ru, E-mail: jiangru0576@163.com [Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, Taizhou University, Taizhou, Zhejiang 318000 (China); Department of Environmental Engineering, Taizhou University, Taizhou, Zhejiang 318000 (China); Fu, Yong-Qian [Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, Taizhou University, Taizhou, Zhejiang 318000 (China); Li, Rong-Rong [College of Pharmaceutical and Chemical Engineering, Taizhou University, Taizhou, Zhejiang 318000 (China); Yao, Jun; Jiang, Sheng-Tao [Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, Taizhou University, Taizhou, Zhejiang 318000 (China); Department of Environmental Engineering, Taizhou University, Taizhou, Zhejiang 318000 (China)

2016-04-30

Graphical abstract: - Highlights: • The NiFe{sub 2}O{sub 4} was decorated on ZnO surface by a hydrothermal method. • NiFe{sub 2}O{sub 4}/ZnO hybrids show high adsorption capacity and excellent photostability. • The main active species in dye decolorization by NiFe{sub 2}O{sub 4}/ZnO hybrids are ·OH and h{sup +}. • NiFe{sub 2}O{sub 4}/ZnO hybrids can be easily separated by an external magnet. - Abstract: Novel multifunctional NiFe{sub 2}O{sub 4}/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 NiFe{sub 2}O{sub 4}/ZnO hybrids were systematically investigated using congo red as a model contaminant. With the introduction of NiFe{sub 2}O{sub 4}, NiFe{sub 2}O{sub 4}/ZnO hybrids can absorb the whole light from 300 nm to 700 nm. The adsorption capacity (221.73 mg g{sup −1}) of NiFe{sub 2}O{sub 4}/ZnO hybrids is higher than those of NiFe{sub 2}O{sub 4}, ZnO and mechanically mixed NiFe{sub 2}O{sub 4}/ZnO hybrids. The removal of congo red solution (20 mg L{sup −1}) by NiFe{sub 2}O{sub 4}/ZnO hybrids was about 94.55% under simulated solar light irradiation for 10 min. ·OH and h{sup +} play important roles in the decolorization of congo red solution by NiFe{sub 2}O{sub 4}/ZnO hybrids under simulated solar light irradiation. The decolorization efficiency of congo red solution is 97.23% for the fifth time by NiFe{sub 2}O{sub 4}/ZnO hybrids under simulate solar light irradiation, indicating the high photostability and durability. NO{sub 3}{sup −} and Cl{sup −} anions which are ubiquitous components in dye-containing wastewater have negligible influence on the effectiveness of NiFe{sub 2}O{sub 4}/ZnO hybrids. Moreover, the magnetic NiFe{sub 2}O{sub 4}/ZnO hybrids can be easily separated from the reacted solution by an external magnet.

Influence of the interface on the magnetic properties of NiZn ferrite thin films treated by proton irradiation

Energy Technology Data Exchange (ETDEWEB)

Jiang, X.D. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Guo, D.W. [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Zhang, C.H., E-mail: c.h.zhang@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Fan, X.L.; Chai, G.Z. [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Xue, D.S., E-mail: xueds@lzu.edu.cn [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China)

2015-09-01

In order to systematically investigate the influence of the interface on the magnetic properties, polycrystalline NiZn ferrite thin films were irradiated with 60 keV proton in the dose range from 5 × 10{sup 12} to 5 × 10{sup 16} ions/cm{sup 2}. A non-destructive approach by proton irradiation was found to finely adjust the magnetic properties of polycrystalline NiZn ferrite thin films such as coercivity, perpendicular magnetic anisotropy as well as the effective g value. The coercivity is about 725 Oe for high proton dose ferrite, which is twice larger than the unirradiated one. The ferromagnetic resonance measurements indicated that perpendicular magnetic anisotropy and the effective g value increase with the irradiation dose. Our finding indicates that all modifications of these magnetic properties were associated with the change of interface due to the diffusion and the stress induced by proton irradiation. The change of the effective g value is a result of lattice expansion and the decrease of the magnetic dipole interaction between the columnar grains. This work provides a feasible way to tailor the magnetic properties of thin films by ion irradiation and promotes investigations for the stability of magnetic thin film devices in space or unclear radiation environments.

Development and manufacture of printable next-generation gel polymer ionic liquid electrolyte for Zn/MnO2 batteries

International Nuclear Information System (INIS)

Winslow, R; Wang, Z; Wright, P; Wu, C H; Kim, B; Evans, J; Keif, M

2013-01-01

While much energy storage research focuses on the performance of individual components, such as the electrolyte or a single electrode, few investigate the electrochemical system as a whole. This research reports on the design, composition, and performance of a Zn/MnO 2 battery as affected by the manufacturing method and next-generation gel polymer electrolyte composed of the ionic liquid [BMIM][Otf], ZnOtf salt, and PVDF-HFP polymer binder. Materials and manufacturing tests are discussed with a focus on water concentration, surface features as produced by printing processes, and the effect of including a gel polymer phase. Cells produced for this research generated open circuit voltages from 1.0 to 1.3 V. A dry [BMIM][Otf] electrolyte was found to have 87.3 ppm of H 2 O, while an electrolyte produced in ambient conditions contained 12400 ppm of H 2 O. Cells produced in a dry, Ar environment had an average discharge capacity of 0.0137 mAh/cm 2 , while one produced in an ambient environment exhibited a discharge capacity at 0.05 mAh/cm 2 . Surface features varied significantly by printing method, where a doctor blade produced the most consistent features. The preliminary results herein suggest that water, surface roughness, and the gel polymer play important roles in affecting the performance of printed energy storage

Development and manufacture of printable next-generation gel polymer ionic liquid electrolyte for Zn/MnO2 batteries

Science.gov (United States)

Winslow, R.; Wu, C. H.; Wang, Z.; Kim, B.; Keif, M.; Evans, J.; Wright, P.

2013-12-01

While much energy storage research focuses on the performance of individual components, such as the electrolyte or a single electrode, few investigate the electrochemical system as a whole. This research reports on the design, composition, and performance of a Zn/MnO2 battery as affected by the manufacturing method and next-generation gel polymer electrolyte composed of the ionic liquid [BMIM][Otf], ZnOtf salt, and PVDF-HFP polymer binder. Materials and manufacturing tests are discussed with a focus on water concentration, surface features as produced by printing processes, and the effect of including a gel polymer phase. Cells produced for this research generated open circuit voltages from 1.0 to 1.3 V. A dry [BMIM][Otf] electrolyte was found to have 87.3 ppm of H2O, while an electrolyte produced in ambient conditions contained 12400 ppm of H2O. Cells produced in a dry, Ar environment had an average discharge capacity of 0.0137 mAh/cm2, while one produced in an ambient environment exhibited a discharge capacity at 0.05 mAh/cm2. Surface features varied significantly by printing method, where a doctor blade produced the most consistent features. The preliminary results herein suggest that water, surface roughness, and the gel polymer play important roles in affecting the performance of printed energy storage.

Magnetic hyperfine field in Tb Zn compound measured by PAC spectroscopy using {sup 111}Cd and {sup 140}Ce

Energy Technology Data Exchange (ETDEWEB)

Bosch-Santos, B.; Cabrera-Pasca, G.A.; Carbonari, A.W.; Costa, M.S.; Saxena, R.N., E-mail: brianna@usp.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-07-01

The ferromagnetic compound Tb Zn has been investigated by perturbed {gamma}-{gamma} angular correlation (PAC) spectroscopy using {sup 111}In{yields}{sup 111}Cd (t{sub 1/2} = 85 ns) and {sup 140}La{yields}{sup 140}Ce (t{sub 1/2} = 3,4 ns) as probe nuclei. Measurements were carried out in the temperature range of 10 - 295K for the {sup 111}Cd probe and below Curie temperature (T{sub C}) for the {sup 140}Ce probe. The study of magnetic properties of rare earth (R) and zinc compounds of the type RZn is interesting because Zn ion is a closed shell atom and the rare earth elements present a localized magnetism associated with 4f electrons, which do not participate in chemical bonds. Therefore, the magnetic properties of these compounds are only originated from the 4f electrons of rare earth. Furthermore, the compounds exhibit the highly symmetric cubic structure of the CsCl prototype and have a Curie temperature of TbZn is T{sub C} {approx} 204 K. (author)

Investigation of structural, surface morphological, optical properties and first-principles study on electronic and magnetic properties of (Ce, Fe)-co doped ZnO

Energy Technology Data Exchange (ETDEWEB)

Arul Mary, J. [Catalysis and Nanomaterials Research Laboratory, Department of Chemistry Loyola College, Chennai 600 034 (India); Judith Vijaya, J., E-mail: jjvijayaloyola@yahoo.co.in [Catalysis and Nanomaterials Research Laboratory, Department of Chemistry Loyola College, Chennai 600 034 (India); Bououdina, M. [Departments of Physics, College of Science, University of Bahrain, PO Box 32038 Kingdom of Bahrain (Bahrain); John Kennedy, L. [Materials Division, School of Advanced Sciences, Vellore Institute of Technology (VIT) University, Chennai Campus, Chennai 600 127 (India); Daie, J.H.; Song, Y. [School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, 2 West Wenhua Road, Weiahi 264209 (China)

2015-01-01

We report on the synthesis of ((Zn{sub 1−2x}Ce{sub x}Fe{sub x}) O (x=0.00, 0.01, 0.02, 0.03, 0.04 and 0.05)) nanoparticles via microwave combustion by using urea as a fuel. To understand how the dopant influenced the structural, magnetic and optical properties of nanoparticles, it was characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectra and vibrating sample magnetometer (VSM). The stability and magnetic properties of Ce and Fe co-doped ZnO were probed by first principle calculations. From the analysis of X-ray diffraction, the samples are identified with the wurtzite crystal structure. The change in lattice parameters, micro-strain, and a small shift in XRD peaks confirms the substitution of co dopants into the ZnO lattice. Morphological investigation of the products revealed the existence of irregular shapes, such as spherical, spherodial and hexagonal. DRS measurements showed a decrease in the energy gap with increasing dopants contents, probably due to an increase in the lattice parameters. PL spectra consist of visible emission, due to the electronic defects, which are related to deep level emissions, such as oxide antisite (O{sub Zn}), interstitial zinc (Zn{sub i}), interstitial oxygen (O{sub i}) and zinc vacancy (V{sub Zn}). Magnetic measurements showed a ferromagnetic behavior for all the doped samples at room temperature. The first principle calculation results showed that the Ce governs the stability, while the Fe adjusts the magnetic characteristics in the Ce and Fe co-doped ZnO.

Investigation on structure, electronic and magnetic properties of Cr doped (ZnO)12 clusters: First-principles calculations

Science.gov (United States)

Liu, Huan; Zhang, Jian-Min

2018-05-01

The structural, electronic, and magnetic properties of (ZnO)12 clusters doped with Cr atoms have been investigated by using spin-polarized first-principles calculations. The exohedral a3 isomer is favorable than endohedral a2 isomer. The isomer a1 and a5 respectively have the narrowest and biggest gap between highest unoccupied molecular orbital and the lowest unoccupied molecular orbital (HOMO-LUMO) of 0.473 and 1.291 eV among these five monodoped isomers. The magnetic moment may be related to the local environment around the Cr atom that the a2 isomer whose total magnetic moment is 6 μB while the other monodoped isomers which all isomers have nearly total magnetic moments 4 μB . For Cr-doped (ZnO)12 on a1 or a3 isomer, the DOS of spin-up channel cross the Fermi level EF showing a finite magnitude near the Fermi level which might be useful for half metallic character. For the bidoped cases, the exohedral isomers are found to be most favorable. Including all bipoed isomers of substitutional, exohedral and endohedral bidoped clusters, the total magnetic moment of the ferromagnetic (antiferromagnetic) state is 8 (0) μB and the HOMO-LUMO gap of antiferromagnetic state is slightly larger than that of ferromagnetic state. The magnetic coupling between the Cr atoms in bidoped configurations is mainly governed by the competition between direct Cr and Cr atoms antiferromagnetic interaction and the ferromagnetic interaction between two Cr atoms via O atom due to strong p-d hybridization. Most importantly, we show that the exohedral bidoped (ZnO)12 clusters favor the ferromagnetic state, which may have the future applications in spin-dependent magneto-optical and magneto-electrical devices.

Magnetic behaviour of nano-particles of Fe2.8Zn0.2O4

Indian Academy of Sciences (India)

Magnetic behaviour of nano-particles of Fe2.8Zn0.2O4. SUBHASH CHANDER, SEEMA LAKHANPAL, ANJALI KRISHNAMURTHY,. BIPIN K SRIVASTAVA and V K ASWAL∗. Department of Physics, University of Rajasthan, Jaipur 302 004, India. *Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 ...

The investigation of Ce doped ZnO crystal: The electronic, optical and magnetic properties

Science.gov (United States)

Wen, Jun-Qing; Zhang, Jian-Min; Qiu, Ze-Gang; Yang, Xu; Li, Zhi-Qin

2018-04-01

The electronic, optical and magnetic properties of Ce doped ZnO crystal have been studied by using first principles method. The research of formation energies show that Ce doped ZnO is energetically stable, and the formation energies reduce from 6.25% to 12.5% for Ce molar percentage. The energy band is still direct band gap after Ce doped, and band gap increases with the increase of Cesbnd Ce distance. The Fermi level moves upward into conduction band and the DOS moves to lower energy with the increase of Ce concentration, which showing the properties of n-type semiconductor. The calculated optical properties imply that Ce doped causes a red-shift of absorption peaks, and enhances the absorption of the visible light. The transition from ferromagnetic to antiferromagnetic has been found in Ce doped ZnO.

Synthesis, structural investigation and magnetic properties of Zn2+ substituted cobalt ferrite nanoparticles prepared by the sol–gel auto-combustion technique

International Nuclear Information System (INIS)

Raut, A.V.; Barkule, R.S.; Shengule, D.R.; Jadhav, K.M.

2014-01-01

Structural morphology and magnetic properties of the Co 1−x Zn x Fe 2 O 4 (0.0≤x≥1.0) spinel ferrite system synthesized by the sol–gel auto-combustion technique using nitrates of respective metal ions have been studied. The ratio of metal nitrates to citric acid was taken at 1:3. The as prepared powder of cobalt zinc ferrite was sintered at 600 °C for 12 h after TG/DTA thermal studies. Compositional stoichiometry was confirmed by energy dispersive analysis of the X-ray (EDAX) technique. Single phase cubic spinel structure of Co–Zn nanoparticles was confirmed by XRD data. The average crystallite size (t), lattice constant (a) and other structural parameters of zinc substituted cobalt ferrite nanoparticles were calculated from XRD followed by SEM and FTIR. It is observed that the sol–gel auto-combustion technique has many advantages for the synthesis of technologically applicable Co–Zn ferrite nanoparticles. The present investigation clearly shows the effect of the synthesis method and possible relation between magnetic properties and microstructure of the prepared samples. Increase in nonmagnetic Zn 2+ content in cobalt ferrite nanoparticles is followed by decrease in n B , M s and other magnetic parameters. Squareness ratio for the Co-ferrite was 1.096 at room temperature. - Highlights: • Co–Zn nanoparticles are prepared by sol–gel auto-combustion method. • Structural properties were characterized by XRD, SEM, and FTIR. • Compositional stoichiometry was confirmed by EDAX analysis. • Magnetic parameters were measured by the pulse field hysteresis loop technique

Microstructure and magnetic studies of Mg-Ni-Zn-Cu ferrites

International Nuclear Information System (INIS)

Bachhav, S.G.; Patil, R.S.; Ahirrao, P.B.; Patil, A.M.; Patil, D.R.

2011-01-01

Highlights: → Ni x Mg 0.5-x Cu 0.1 Zn 0.4 Fe 2 O 4 ferrite shows spinel structure. → Lattice parameter, X-ray density, porosity increase with increase in Ni content. → The IR spectra show tetrahedral and octahedral complexes. → Initial permeability remains constant with temperature and drops to zero at certain temperature which is in close agreement with Curie temperature. → The Curie temperature shows increasing trend with Ni content. - Abstract: Soft Mg-Ni-Zn-Cu spinel ferrites having general chemical formula Ni x Mg 0.5-x Cu 0.1 Zn 0.4 Fe 2 O 4 (where x 0.1, 0.2, 0.3, 0.4 and 0.5) were prepared by standard double sintering ceramic method. The samples were characterized by X-ray diffraction at room temperature. The X-ray diffraction (XRD) study revealed that lattice parameter decreases with increase in Ni content, resulting in a reduction in lattice strain. The electrical and magnetic properties of the synthesized ferrites have been investigated as a function of temperature. The variation of initial permeability and AC susceptibility with temperature exhibits normal ferrimagnetic behavior. The variation of initial permeability with frequency is studied. The Curie temperature (T C ) in the present work was determined from initial permeability and AC susceptibility. The Curie temperature increases with Ni content.

Structure and magnetic properties of Zn1-xCoxO single-crystalline nanorods synthesized by a wet chemical method

International Nuclear Information System (INIS)

Wang Hao; Wang, H B; Yang, F J; Chen, Y; Zhang, C; Yang, C P; Li, Q; Wong, S P

2006-01-01

A novel approach for the synthesis of cobalt-doped ZnO single-crystalline nanorods based on a wet chemical reaction has been developed. The as-doped ZnO nanorods have a length between 0.3 and 0.6 μm and a diameter between 30 and 60 nm. Structure and composition analyses indicate that the cobalt is incorporated into the ZnO lattice, forming a solid solution without any precipitation. Magnetic property measurements reveal that there is room-temperature ferromagnetism in the Zn 1-x Co x O nanorods with T c higher than 300 K

Strong sp-d exchange coupling in ZnMnTe/ZnMgTe core/shell nanowires

Energy Technology Data Exchange (ETDEWEB)

Wojnar, Piotr; Janik, Elzbieta; Szymura, Malgorzata; Zaleszczyk, Wojciech; Kret, Slawomir; Klopotowski, Lukasz; Wojciechowski, Tomasz; Baczewski, Lech T.; Wiater, Maciej; Karczewski, Grzegorz; Wojtowicz, Tomasz; Kossut, Jacek [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Suffczynski, Jan; Papierska, Joanna [Institute of Experimental Physics, Warsaw University, ul. Hoza 69, 00-681 Warsaw (Poland)

2014-07-15

In this work, our recent progress in the growth and optical studies of telluride nanowire heterostructures containing a small molar fraction of magnetic Mn-ions of only a few percent is overviewed. ZnMnTe/ZnMgTe core/shell nanowires (NWs) are grown by molecular beam epitaxy by employing the vapor-liquid-solid growth mechanism assisted with gold catalyst. The structures are studied by means of photoluminescence and microphotoluminescence in an external magnetic field. In the first step, however, an activation of the near band edge emission from ZnTe and ZnMnTe nanowires is described, which is achieved by coating the nanowires with shells made of ZnMgTe. The role of these shells is to passivate Zn(Mn)Te surface states. The incorporation of Mn ions into the crystalline lattice of ZnMnTe nanowires is manifested as a considerable blue shift of near band edge emission with increasing Mn concentration inside the nanowire cores, which reflects directly the increase of their energy gap. In an external magnetic field the near band edge emission exhibits a giant spectral redshift accompanied by an increase of the circular polarization of the emitted light. Both effect are fingerprints of giant Zeeman splitting of the band edges due to sp-d exchange interaction between the band carriers and magnetic Mn-ions. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Effects of sintering atmosphere and temperature on structural and magnetic properties of Ni-Cu-Zn ferrite nano-particles: Magnetic enhancement by a reducing atmosphere

Energy Technology Data Exchange (ETDEWEB)

Gholizadeh, Ahmad, E-mail: gholizadeh@du.ac.ir; Jafari, Elahe, E-mail: ah_gh1359@yahoo.com

2017-01-15

In this work, effects of sintering atmosphere and temperature on structural and magnetic properties of Ni{sub 0.3}Cu{sub 0.2}Zn{sub 0.5}Fe{sub 2}O{sub 4} nanoparticles prepared by citrate precursor method have been studied. The structural characterization of the samples by X-ray powder diffraction and FT-IR spectroscopy is evidence for formation of a cubic structure with no presence of impurity phase. Calculated values of crystallite size and unit cell parameter show an increase with sintering temperature under different atmospheres. Variation of saturation magnetization with sintering temperature and atmosphere can be attributed to change of three factors: magnetic core size, inversion parameter and the change of Fe{sup 3+}-ion concentration due to the presence of Fe{sup 4+} and Fe{sup 2+} ions. The saturation magnetization gradually grows with sintering temperature due to increase of magnetic core size and a maximum 63 emu/g was achieved at 600 °C under carbon monoxide-ambient atmosphere. - Highlights: • Different sintering atmosphere and temperature cause substantial differences in Ni{sub 0.3}Cu{sub 0.2}Zn{sub 0.5}Fe{sub 2}O{sub 4} nanoparticles. • The saturation magnetization gradually grows. • A maximum 63 emu/g was achieved at 600 °C under a reducing atmosphere.

Magnetic and transport properties of Zn0.4Fe2.6O4 thin films with highly preferential orientation

International Nuclear Information System (INIS)

Lu, Z.L.; Zou, W.Q.; Liu, X.C.; Lin, Y.B.; Lu, Z.H.; Wang, J.F.; Xu, J.P.; Lv, L.Y.; Zhang, F.M.; Du, Y.W.

2007-01-01

Highly preferentially oriented Zn 0.4 Fe 2.6 O 4 thin films have been fabricated on Si, SrTiO 3 and ZrO 2 substrates, respectively, using RF magnetron sputtering. All the films show a large saturation magnetization of about 4.2μ B and low coercive field at 300 K and a spin (cluster) glass transition at about 60 K due to the non-magnetic Zn 2+ ions substitution. Moreover, the fairly high spin polarization of the carrier at 300 K has been confirmed by both the giant magnetoresistance and anomalous Hall coefficient measurements

Magnetic ordering and electrical resistivity in Co0.2Zn0.8Fe2O4 spinel oxide

International Nuclear Information System (INIS)

Bhowmik, R.N.; Ranganathan, R.; Ghosh, B.; Kumar, S.; Chattopadhyay, S.

2008-01-01

We report the magnetic, Moessbauer spectroscopy and resistivity measurements in order to understand the electronic behaviour of bulk Co 0.2 Zn 0.8 Fe 2 O 4 spinel oxide. The effect of magnetic order on electrical behaviour is observed from the resistivity measurements in the absence and presence of magnetic field. The analysis of Moessbauer spectra suggests the absence of Fe 2+ ions in the system, which implies that complete hopping of charge carriers between localized Fe 3+ /Co 2+ and Fe 2+ /Co 3+ pair of ions in B sublattice is not the favourable mechanism in Co 0.2 Zn 0.8 Fe 2 O 4 . We suggest that electrical behaviour of the present sample may be consistent with a model of fractional charge transfer via Fe B 3+ -O 2- -Co B 2+ superexchange path

Synthesis and sonocatalytic performance of a ternary magnetic MIL-101(Cr)/RGO/ZnFe2O4 nanocomposite for degradation of dye pollutants.

Science.gov (United States)

Nirumand, Ladan; Farhadi, Saeed; Zabardasti, Abedin; Khataee, Alireza

2018-04-01

In this study, new ternary magnetic MIL-101(Cr)/RGO/ZnFe 2 O 4 catalyst (with 30% wt of ZnFe 2 O 4 ) was synthesized via a hydrothermal route for sonodegradation of organic dyes. The structural, optical and magnetic properties of the nanocomposite were detected by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy (UV-visible), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) spectroscopy, vibrating sample magnetometer (VSM), atomic force microscopy (AFM), Raman spectroscopy and BET surface area analysis. To evaluate the sonocatalytic activity of the as-prepared MIL-101(Cr)/RGO/ZnFe 2 O 4 nanocomposite, the H 2 O 2 -assisted degradation of organic dyes such as congo red (CR), methylene blue (MB), Rhodamine B (RhB) and methyl orange (MO) in aqueous solution was studied under ultrasound irradiation. The obtained results indicated that the ternary MIL-101(Cr)/RGO/ZnFe 2 O 4 nanocomposite had better performance for sonodegradation of these dyes than MIL-101(Cr)/RGO, pure MIL-101(Cr) or ZnFe 2 O 4 . The enhanced sonocatalytic performance of the as-prepared ternary nanocomposite could be attributed to the fast generation and separation of charge carriers (electrons and holes) in ZnFe 2 O 4 and MIL-101(Cr) and their transfer to the surface of graphene sheets. Moreover, the relatively high specific surface area of the MIL-101(Cr)/rGO and magnetic property of ZnFe 2 O 4 improve the degradation efficiency of the dyes. The recovery of the ternary magnetic sonocatalyst from treated water could be easily achieved using an external magnetic field. The main influence factors on the sonocatalytic activity such as catalyst dosage and dye initial concentration were also investigated. The trapping experiments indicated that OH radicals are the prominent active species in dye degradation. In addition, the reusability test, was also carried out to ensure the stability of the employed sonocatalyst

Synthesis of ZnFe2O4/ZnO nanocomposites immobilized on graphene with enhanced photocatalytic activity under solar light irradiation

International Nuclear Information System (INIS)

Sun, Lin; Shao, Rong; Tang, Lanqin; Chen, Zhidong

2013-01-01

Highlights: ► ZnFe 2 O 4 /ZnO nanocomposites immobilized on graphene were successfully prepared. ► The photocatalyst exhibited excellent reactivity under solar light irradiation. ► The photocatalysts could be recycled by external magnetic field conveniently. ► The photocatalytic mechanism of the novel material was proposed in detail. -- Abstract: Magnetically recyclable ZnFe 2 O 4 /ZnO nanocomposites immobilized on different content of graphene with favorable photocatalytic activity under solar light irradiation were successfully prepared on the basis of an ultrasound aided solution method. The molar ratio of ZnFe 2 O 4 to ZnO and the content of graphene could be controlled by adjusting the amount of zinc salts and graphene oxide dispersions. The most excellent photocatalytic activity under solar light irradiation was displayed when the molar ratio of ZnFe 2 O 4 to ZnO was 0.1 and the weight ratio of graphene to ZnFe 2 O 4 /ZnO was 0.04. Furthermore, the presence of magnetical ZnFe 2 O 4 will facilitate the recycling process of photocatalyst nanoparticles

Characterization of Mn doped ZnO nanopowder

Energy Technology Data Exchange (ETDEWEB)

Schlenker, Eva; Bakin, Andrey; Al-Suleiman, Mohamed; Wehmann, Hergo-Heinrich; Waag, Andreas [Institute of Semiconductor Technology, TU Braunschweig (Germany); Schmid, Herbert; Mader, Werner [Institute for Inorganic Chemistry, University Bonn (Germany); Bremers, Heiko; Hangleiter, Andreas [Institute of Applied Physics, TU Braunschweig (Germany)

2008-07-01

In the quest of materials for spintronic applications, diluted magnetic semiconductors recently attracted much attention. The main challenge is finding a ferromagnetic material with Curie temperature T{sub c}>300 K whose magnetic properties can be controlled electrically. The interest was particularly focused on Zn(TM)O since theoretical calculations predict that ZnO containing Mn could exhibit ferromagnetism with T{sub c} above room temperature. In the present study, the structural and magnetic properties of Mn doped ZnO nanopowder are investigated and compared to undoped ZnO crystals. Doping of ZnO with Mn results in increased lattice constants as revealed by XRD. However, an inhomogeneous distribution of the Mn dopants within the nanopowder was revealed by energy-dispersive X-ray and electron energy-loss spectroscopy. Magnetic properties are investigated by means of SQUID measurements on aggregates of powder particles as well as by MFM to study the behavior of single grains. The MFM image differs significantly from the topography as imaged by AFM and suggests the existence of long-ranging magnetic signals emerging from the sample.

Effects of La{sup 3+}-Zn{sup 2+} doping on the structure, magnetic, electrical, and dielectric properties of low temperature sintered Sr-hexaferrites

Energy Technology Data Exchange (ETDEWEB)

Peng, Long, E-mail: penglong@cuit.edu.cn [Sichuan Province Key Laboratory of Information Materials and Devices Application, College of Optoelectronic Technology, Chengdu University of Information Technology, Chengdu 610225 (China); Li, Lezhong; Zhong, Xiaoxi [Sichuan Province Key Laboratory of Information Materials and Devices Application, College of Optoelectronic Technology, Chengdu University of Information Technology, Chengdu 610225 (China); Hu, Yuebin [Chengdu Industrial Vocational and Technical College, Chengdu 610213 (China); Chen, Sanming [Sichuan Province Key Laboratory of Information Materials and Devices Application, College of Optoelectronic Technology, Chengdu University of Information Technology, Chengdu 610225 (China)

2017-04-15

The Sr{sub 1-x}La{sub x}Fe{sub 12-x}Zn{sub x}O{sub 19} (x=0–0.3) hexaferrites with Bi{sub 2}O{sub 3} additive were prepared by microwave sintering method at low sintering temperatures, and their crystal structure, microstructure, magnetic, electrical, and dielectric properties were studied. The results show that the pure M-type phase is obtained for the ferrites with x≤0.2. With x further increasing to 0.3, the multiphase structure is inevitably formed, where the LaFeO{sub 3} phase coexists with the M-type phase. In the single phase region, the varied magnetic, electrical, and dielectric properties with La{sup 3+}-Zn{sup 2+} doping amount are well explained by the occupancy effects of La{sup 3+} and Zn{sup 2+} in magnetoplumbite structure. It is suggested that the Zn{sup 2+} ions replace the Fe{sup 3+} ions at 4f{sub 1} site with x≤0.15, but the substitution of Zn{sup 2+} for Fe{sup 3+} occurs at 2b site preferentially when the La{sup 3+}-Zn{sup 2+} doping amount exceeds 0.15. - Highlights: • The low temperature sintered Sr{sub 1-x}La{sub x}Fe{sub 12-x}Zn{sub x}O{sub 19} (x=0–0.3) hexaferrites are successfully prepared. • The La{sup 3+}-Zn{sup 2+} ions partially substitute the Sr{sup 2+}-Fe{sup 3+} ions in a doping region of x≤0.2. • Effects of La{sup 3+}-Zn{sup 2+} doping on the magnetic, electrical and polarization properties are revealed. • The substitution of Zn{sup 2+} for Fe{sup 3+} occurs at 4f{sub 1} site and 2b site before and after x=0.15, respectively.

Experimental and theoretical investigations on magnetic behavior of (Al,Co) co-doped ZnO nanoparticles.

Science.gov (United States)

Jayakumar, O D; Achary, S N; Sudakar, C; Naik, R; Salunke, H G; Rao, Rekha; Peng, X; Ahuja, R; Tyagi, A K

2010-08-01

We present the structural and magnetic properties of Zn(0.95-x)Co(0.05)Al(x)O (x = 0.0 to 0.1) nanoparticles, synthesized by a novel sol-gel route followed by pyrolysis. Powder X-ray diffraction data confirms the formation of a single phase wurtzite type ZnO structure for all the compositions. The Zn(0.95)Co(0.05)O nanoparticles show diamagnetic behavior at room temperature. However, when Al is co-doped with Co with x = 0.0 to 0.10 in Zn(0.95-x)Co(0.05)Al(x)O, a systematic increase in ferromagnetic moment is observed up to x = 0.07 at 300 K. Above x = 0.07 (e.g. for x = 0.10) a drastic decrease in ferromagnetic nature is observed which is concomitant with the segregation of poorly crystalline Al rich ZnO phase as evidenced from TEM studies. Theoretical studies using density functional calculations on Zn(0.95-x)Co(0.05)Al(x)O suggest that the partial occupancy of S2 states leads to an increased double exchange interaction favoring the ferromagnetic ground states. Such ferromagnetic interactions are favorable beyond a threshold limit. At a high level doping of Al, the exchange splitting is reduced, which suppresses the ferromagnetic ordering.

Evaluation of structural, morphological and magnetic properties of CuZnNi (Cu{sub x}Zn{sub 0.5−x}Ni{sub 0.5}Fe{sub 2}O{sub 4}) nanocrystalline ferrites for core, switching and MLCI’s applications

Energy Technology Data Exchange (ETDEWEB)

Akhtar, Majid Niaz, E-mail: majidniazakhtar@ciitlahore.edu.pk [Department of Physics, COMSATS Institute of Information Technology, Lahore, 54000 Pakistan (Pakistan); Khan, Muhammad Azhar [Department of Physics, The Islamia University of Bahawalpur, Bahawalpur, 63100 Pakistan (Pakistan); Ahmad, Mukhtar [Department of Physics, COMSATS Institute of Information Technology, Lahore, 54000 Pakistan (Pakistan); Nazir, M.S. [Department of Chemical Engineering, COMSATS Institute of Information Technology, Lahore, 54000 Pakistan (Pakistan); Imran, M.; Ali, A.; Sattar, A. [Department of Physics, COMSATS Institute of Information Technology, Lahore, 54000 Pakistan (Pakistan); Murtaza, G. [Centre for Advanced Studies in Physics, G.C. University, Lahore (Pakistan)

2017-01-01

The influence of Cu substitution on the structural and morphological characteristics of Ni–Zn nanocrystalline ferrites have been discussed in this work. The detailed and systematic magnetic characterizations were also done for Cu substituted Ni–Zn nanoferrites. The nanocrystalline ferrites of Cu substituted Cu{sub x}Zn{sub 0.5−x}Ni{sub 0.5}Fe{sub 2}O{sub 4} ferrites (x=0, 0.1, 0.2, 0.3, 0.4 and 0.5) were synthesized using sol gel self-combustion hybrid method. X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscope (TEM) and Vibrating sample magnetometer (VSM) were used to investigate the properties of Cu substituted nanocrystalline ferrites. Single phase structure of Cu substituted in Ni–Zn nanocrystalline ferrites were investigated for all the samples. Crystallite size, lattice constant and volume of the cell were found to increase by increasing Cu contents in spinel structure. The better morphology with well-organized nanocrystals of Cu–Zn–Ni ferrites at x=0 and 0.5 were observed from both FESEM and TEM analysis. The average grain size was 35–46 nm for all prepared nanocrystalline samples. Magnetic properties such as coercivity, saturation, remanence, magnetic squareness, magneto crystalline anisotropy constant (K) and Bohr magneton were measured from the recorded M–H loops. The magnetic saturation and remanence were increased by the incorporation of Cu contents. However, coercivity follow the Stoner-Wolforth model except for x=0.3 which may be due to the site occupancy and replacement of Cu contents from octahedral site. The squareness ratio confirmed the super paramgnetic behaviour of the Cu substituted in Ni–Zn nanocrystalline ferrites. Furthermore, Cu substituted Ni–Zn nanocrystalline ferrites may be suitable for many industrial and domestic applications such as components of transformers, core, switching, and MLCI’s due to variety of the soft magnetic characteristics. - Highlights

Ag@ZnO core-shell nanoparticles study by first principle: The structural, magnetic and optical properties

Energy Technology Data Exchange (ETDEWEB)

Cheng, Hai-Xia [Department of Physics, University of Science and Technology Beijing, Beijing 100083 (China); Wang, Xiao-Xu [Department of Physics, University of Science and Technology Beijing, Beijing 100083 (China); Beijing Computing Center, Beijing 100094 (China); Hu, Yao-Wen [Department of Physics, Tsinghua University, Beijing 100084 (China); Song, Hong-Quan; Huo, Jin-Rong; Li, Lu [Department of Physics, University of Science and Technology Beijing, Beijing 100083 (China); Qian, Ping, E-mail: ustbqianp@163.com [Department of Physics, University of Science and Technology Beijing, Beijing 100083 (China); Song, Yu-Jun [Department of Physics, University of Science and Technology Beijing, Beijing 100083 (China)

2016-12-15

Ag@ZnO core-shell nanoparticles of around 72 atoms have been investigated by the density functional theory, revealing proving for the first time that the core-shell structure exhibits a shrinkage phenomenon from outer shell in agreement with the other studies in literatures. Our calculations predict that the Ag@ZnO core-shell structure is a ferromagnetic spin polarized state, and the magnetism mainly stems from the spin splitting of 2p electrons of O atoms. In addition, the total and partial DOS of Ag@ZnO indicate that the nanostructure is a half-metallic nanoparticle and has the characters of the p-type semiconductor. Furthermore, the optical properties calculations show that the absorption edge of Ag@ZnO have a red shift and good photocatalysis compare to that of the bulk ZnO. These results of the Ag@ZnO core-shell structure obtain a well agreement with the experimental measurement. - Graphical abstract: Geometric structure of (a) Ag@ZnO core-shell nanostructure; (b) the core of Ag; (c) the shell of ZnO The core-shell nanoparticle Ag@ZnO contains Ag inner core of radius of 4 Å and ZnO outer shell with thickness of 2 Å. Ag@ZnO core-shell nanoparticles of around 72 atoms have been proved for the first time that the core-shell structure exhibit a shrinkage phenomenon from outer shell. Our calculations predict that the Ag@ZnO core-shell structure is a half-metallic nanoparticle and has the characters of the p-type semiconductor. The absorption edge of Ag@ZnO have a red shift and get good photo-catalysis compare to that of the bulk ZnO.

Analysis on the energetics, magnetism and electronic properties in a 45° ZnO grain boundary doped with Gd

KAUST Repository

Devi, Assa Aravindh Sasikala

2018-04-13

The structural stability and magnetic properties of a grain boundary (GB) formed by aligning two ZnO single crystals oriented at an angle of 45° is investigated by density functional theory, using generalized gradient approximation (GGA) and taking the U parameter into consideration for the 4f impurity states. We found that the GB is stable with no dangling bonds and inter-granular structures. The stability of defects such as Gd substituted to the Zn site (Gd), Zn vacancy (V) and O vacancy (V) as well as defect complexes Gd-Gd, Gd-V, and Gd-V are analyzed using formation energy calculations. It is found that Gd-Gd clusters prefers to form at the GB. The spin polarization at the Gd sites is too localized and the exchange coupling energy is insufficient to overcome the thermal fluctuations. However, we show that the presence of V increases the hybridization between p orbitals of O as well as d orbitals of Zn, which can assist in increasing the magnetic polarization of the system. This work advances the understanding of the ferromagnetism in Gd-doped ZnO, indicating that Gd clustering at the GB is not likely to contribute to the ferromagnetism.

Soil pH effects on the comparative toxicity of dissolved zinc, non-nano and nano ZnO to the earthworm Eisenia fetida.

Science.gov (United States)

Heggelund, Laura R; Diez-Ortiz, Maria; Lofts, Stephen; Lahive, Elma; Jurkschat, Kerstin; Wojnarowicz, Jacek; Cedergreen, Nina; Spurgeon, David; Svendsen, Claus

2014-08-01

To determine how soil properties influence nanoparticle (NP) fate, bioavailability and toxicity, this study compared the toxicity of nano zinc oxide (ZnO NPs), non-nano ZnO and ionic ZnCl2 to the earthworm Eisenia fetida in a natural soil at three pH levels. NP characterisation indicated that reaction with the soil media greatly controls ZnO properties. Three main conclusions were drawn. First that Zn toxicity, especially for reproduction, was influenced by pH for all Zn forms. This can be linked to the influence of pH on Zn dissolution. Secondly, that ZnO fate, toxicity and bioaccumulation were similar (including relationships with pH) for both ZnO forms, indicating the absence of NP-specific effects. Finally, earthworm Zn concentrations were higher in worms exposed to ZnO compared to ZnCl2, despite the greater toxicity of the ionic form. This observation suggests the importance of considering the relationship between uptake and toxicity in nanotoxicology studies.

Amorphous Al–Mn coating on NdFeB magnets: Electrodeposition from AlCl3–EMIC–MnCl2 ionic liquid and its corrosion behavior

International Nuclear Information System (INIS)

Chen Jing; Xu Bajin; Ling Guoping

2012-01-01

Amorphous Al–Mn coating was electrodeposited on NdFeB magnets from AlCl 3 –EMIC–MnCl 2 ionic liquid with the pretreatment of anodic electrolytic etching in AlCl 3 –EMIC ionic liquid at room temperature. The microstructure, composition and phase constituents of the coatings were investigated by scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The corrosion resistance of the coatings was tested by means of potentiodynamic polarization and immersion test in 3.5 wt. % NaCl solution. The results show that anodic electrolytic etching in AlCl 3 –EMIC ionic liquid is a satisfactory pretreatment to remove the surface oxide film and favor the adhesion of the Al–Mn alloy coating to the NdFeB substrate. The amorphous Al–Mn alloy coating provides sacrificial anodic protection for NdFeB. It exhibited good corrosion resistance and significantly reduced the corrosion current density of NdFeB by three orders of magnitude at potentiodynamic polarization. - Highlights: ► Amorphous Al–Mn alloy coating was electrodeposited on NdFeB magnet from ionic liquid. ► To remove the surface oxides of NdFeB, anodic etching pretreatment is used. ► The deposited Al–Mn alloy coating shows high adhesion to the NdFeB substrate. ► Corrosion tests show that amorphous Al–Mn alloy coating is anodic coating for NdFeB magnet.

Magnetic and magnetocaloric properties of La{sub 0.7}Ca{sub 0.3}Mn{sub 1−x}Zn{sub x}O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Ho, T.A. [Department of Materials Science and Engineering, Korea University, Seoul 02841 (Korea, Republic of); Lim, S.H., E-mail: sangholim@korea.ac.kr [Department of Materials Science and Engineering, Korea University, Seoul 02841 (Korea, Republic of); Tho, P.T.; Phan, T.L. [Department of Physics and Oxide Research Center, Hankuk University of Foreign Studies, Yongin 17035 (Korea, Republic of); Yu, S.C. [Department of Physics, Chungbuk National University, Cheongju 28644 (Korea, Republic of)

2017-03-15

The magnetic Mn{sup 3+} ions in La{sub 0.7}Ca{sub 0.3}MnO{sub 3} are partially replaced by nonmagnetic Zn{sup 2+} ions to form La{sub 0.7}Ca{sub 0.3}Mn{sub 1−x}Zn{sub x}O{sub 3} compounds (x=0.0, 0.06, 0.08, and 0.1), and their magnetic and magnetocaloric properties are investigated. The Curie temperature decreases drastically from 245 to 70 K as x increases from 0 to 0.1. An analysis using the Banerjee's criterion of the experimental results for magnetization as a function of temperature and magnetic field indicates that the first-to-second order magnetic phase transformation occurs at a threshold composition of x=0.06, which is further supported by the universal curves of the normalized entropy change versus reduced temperature. The maximum magnetic entropy change measured at a magnetic field span of 50 kOe, which occurs near the Curie temperature, decreases from 10.30 to 2.15 J/kg K with the increase of x from 0.0 to 0.1. However, the relative cooling power, an important parameter for practical applications, shows a maximum value of 404 J/kg at x=0.08, which is 1.5 times greater than that observed for the undoped sample. - Highlights: • Magnetic and MCE of La{sub 0.7}Ca{sub 0.3}Mn{sub 1−x}Zn{sub x}O{sub 3} are investigated. • Order of magnetic phase transition is dependent on the Zn doping concentration. • Although the |∆S{sub max}| decreases with increasing x, RCP increase remarkably.

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

International Nuclear Information System (INIS)

Hou, Wei-xiao; Wang, Zhi

2015-01-01

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

Effect of Co2+ and Y3+ ions insertion on the microstructure development and magnetic properties of Ni0.5Zn0.5Fe2O4 powders synthesized using Co-precipitation method

Science.gov (United States)

Rashad, M. M.; Rayan, D. A.; Turky, A. O.; Hessien, M. M.

2015-01-01

Nanocrystalline Ni0.5Zn0.5-xCoxFe2-zYzO4 powders (x=0-0.3 and z from 0 to 0.3) have been synthesized via a facile co-precipitation technique. X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) are utilized in order to study the effect of variation of cobalt and yttrium substitutions and its impact on crystalline size, lattice parameter, X-ray density, microstructure and magnetic properties of the formed powders. X-ray diffraction data indicated that, after doping, all samples consisted of the main spinel phase for the formed precursors precipitated at pH 10 annealed at 1000 oC for 2 h. The lattice parameter and the unit cell were decreased linearly with increasing Co content whereas they were increased with increasing the Y incorporation. Additionally, the porosity was increased with increasing Co concentration while it was decreased with increasing the Y insertion. The mean ionic radii and hopping and bond lengths was decreased with the value of Co2+ and they were increased with the value of Y3+ ion as well as both of Y3+ and Co2+ ions. The microstructures of the produced powders were found to be cubic like structure. The addition of Y3+ ion suppressed the grain size whereas addition of Co2+ ion enhanced the grain growth availably. An examination of the magnetic properties revealed an increase in saturation magnetization with increasing Co and Y concentrations incorporation up to x=0.3. Meanwhile, the formed powders exhibited superparamagnetic characteristics. A high saturation magnetization (77.0 emu/g) was achieved for Ni0.5Zn0.2Co0.3Fe2O4 sample annealed at 1000 oC for 2 h.

Effects of La-Zn substituent and calcination temperature on the microstructure and magnetic properties of Sr-ferrites

Energy Technology Data Exchange (ETDEWEB)

Li, Xiangcheng; Zhao, Zhang; Zhu, Boquan [Wuhan Univ. of Science and Technology (China). State Key Lab. of Refractories and Metallurgy

2015-01-15

In this study, La-Zn-substituted SrFe{sub 12}O{sub 19} ferrites were synthesized using the traditional ceramic process. The by-products of iron oxide scales from a steel plant were used as the main raw materials. The influence of the La-Zn substituent and the calcination temperature on the microstructure and magnetic properties of Sr{sub 1-x}La{sub x}Fe{sub 12-x}Zn{sub x}O{sub 19} ferrites was investigated. The results showed that with the increase in the x value, the crystalline lattice constant of the a- and c-axes and the cell volume decreased. There was no α-Fe{sub 2}O{sub 3} phase in the ferrites when the value of x was 0.3. The corresponding saturation magnetization (M{sub s}) and remnant magnetization (M{sub r}) values were, respectively, about 65 emu g{sup -1} and 39.5 emu g{sup -1}. Both values of M{sub s} and M{sub r} rise to the maximum value. When the calcination temperature was reduced from 1200 C to 1150 C, the average particle size decreased from 0.9 μm to 0.7 μm and M{sub s} remained at 65 emu g{sup -1}. However, the coercivity increased from 2690 Oe to 3100 Oe.

Preparation and property of magnetic photocatalyst BiOCl/Mn{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Feng, Shan; Xu, Longjun, E-mail: xulj@cqu.edu.cn; Liu, Chenglun [State Key Laboratory of Coal Mine Disaster Dynamics and Control (China); Du, Haigang [Liupanshui Normal University, Department of Mining Engineering (China); Xie, Taiping [State Key Laboratory of Coal Mine Disaster Dynamics and Control (China); Zhu, Qianqian [Chongqing University, College of Chemistry and Chemical Engineering (China)

2017-02-15

The magnetic photocatalyst BiOCl/Mn{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4} was prepared by impregnation-calcination method. The structure and properties of the prepared photocatalyst were characterized by FTIR, XRD, SEM, TEM, UV–vis DRS, and VSM. Mn{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4} inhibited the growth along (001) crystal face and promoted (110) crystal surface exposure of BiOCl. The as-prepared magnetic composite appeared flower-like microspheres assembled with nanosheets. The average crystallite size and the nanosheet thickness range of BiOCl/Mn{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4} were 57.6 and 75.7–112.2 nm, respectively. The band gap energy (E{sub g}) of BiOCl/Mn{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4} was 2.48 eV, which was lower than that of BiOCl. The saturation magnetization (Ms), coercive force (Hc), and remanent magnetization (Mr) of BiOCl/Mn{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4} were respectively 4.64 emu g{sup −1}, 50.12 G and 0.09 emu g{sup −1}, indicating a good resistance to demagnetization and paramagnetism. The optimum synthesis condition of BiOCl/Mn{sub x}Zn{sub 1−x}Fe{sub 2}O{sub 4} was obtained by orthogonal experiments, and the degradation ratio of RhB with the photocatalyst was 99.6% at 30 min. After four cycles, the degradation ratio of RhB with the recovered photocatalyst was still above 83%.

Glass additive influence on the sintering behavior, microstructure and microwave magnetic properties of Cu-Bi-Zn co-doped Co2Z ferrites

International Nuclear Information System (INIS)

Hsiang, Hsing-I; Mei, Li-Then; Hsi, Chi-Shiung; Wu, Wei-Cheng; Cheng, Li-Bao; Yen, Fu-Su

2011-01-01

The Bi 2 O 3 -B 2 O 3 -ZnO-SiO 2 (BB35SZ) glass effects on the sintering behavior and microwave magnetic properties of Cu-Bi-Zn co-doped Co 2 Z ferrites were investigated to develop low-temperature-fired ferrites. The glass wetting characteristics on the Co 2 Z ferrite surface, X-ray diffractometer, scanning electron microscopy and a dilatometer were used to examine the BB35SZ glass effect on Co 2 Z ferrite densification and the chemical reaction between the glass and Co 2 Z ferrites. The results indicate that BB35SZ glass can be used as a sintering aid to reduce the densification temperature of Co 2 Z ferrites from 1300 to 900 o C. 3(Ba 0.9 Bi 0.1 O).2(Co 0.8 Cu 0.2 O).12(Fe 1.975 Zn 0.025 O 3 ) ferrite with 2 wt% BB35SZ glass can be densified below 900 o C, exhibiting an initial permeability of 3.4. This process provides a promising candidate for multilayer chip magnetic devices for microwave applications. - Research highlights: → Bi 2 O 3 -B 2 O 3 -ZnO-SiO 2 glass can effectively wet Co 2 Z ferrites and promote Co 2 Z ferrite densification. → The excess substitution of Bi and Zn (x=0.2) and glass addition enhanced Z phase decomposition into U, W and spinel phases, which resulted in magnetic property degradation. → 3(Ba 0.9 Bi 0.1 O).2(Co 0.8 Cu 0.2 O).12(Fe 1.975 Zn 0.025 O 3 ) ferrite with 2 wt% glass can be densified at below 900 o C and exhibits an initial permeability of 3.4, which provides a promising candidate for multilayer chip magnetic devices for microwave applications.

On the sol-gel synthesis and thermal, structural, and magnetic studies of transition metal (Ni, Co, Mn) containing ZnO powders

Energy Technology Data Exchange (ETDEWEB)

Thota, Subhash; Dutta, Titas; Kumar, Jitendra [Materials Science Programme, Indian Institute of Technology Kanpur, Kanpur-208016 (India)

2006-03-01

Transition metal containing ZnO powders (Zn{sub 1-x}M{sub x}O, 0{<=}x{<=}0.30; M = Ni, Mn, Co) have been synthesized by a sol-gel process using zinc acetate dihydrate, respective acetate and oxalic acid as precursors with ethanol as a solvent. The process essentially involves gel formation, drying at 80 {sup 0}C for 24 h to provide the oxalate, and calcination at 500 {sup 0}C for 2 h to undergo an exothermic reaction and yield Zn{sub 1-x}M{sub x}O powder. Their XRD patterns correspond to a wurtzite hcp structure similar to that of pure ZnO, but with the lattice parameters varying slightly with type and extent of doping. It is shown that the dissolution of nickel and cobalt in ZnO is less than 10 at.%, whereas that of manganese lies between 10 and 15 at.%. Other phases that emerge include NiO (hexagonal, a = 2.954 A, c = 7.236 A), ZnCo{sub 2}O{sub 4} (cubic, a = 8.094 A) and ZnMnO{sub 3} (cubic, a = 8.35 A) in the Ni, Co and Mn containing ZnO systems, respectively. Observations of hysteresis loops both at 10 and 320 K and the nature of ESR spectra provide evidence for the ferromagnetic state in nickel containing ZnO powder. Besides, the deviation occurs in the magnetization versus temperature curves in zero field cooled (ZFC) and field cooled (FC) conditions (blocking temperature T{sub B} being 32 K for 5 at.% Ni). The magnetic behaviour of manganese and cobalt doped zinc oxide is, however, different, namely (i) no hysteresis loops (ii) decrease in magnetization with increase of Mn or Co content, and (iii) identical M-T curves under ZFC and FC conditions. The inverse susceptibility versus temperature curves of Zn{sub 1-x}Mn{sub x}O compounds reveal ferrimagnetism with Neel temperature T{sub N} of 4 K for x = 0.02, but antiferromagnetism for x = 0.15 and 0.25 with Curie-Weiss temperature of -43 and -30 K, respectively.

The mechanism of Tc performance for Zn doped MgB2 sintered in magnetic field

International Nuclear Information System (INIS)

Li, W.X.; Li, Y.; Chen, R.H.; Zeng, R.; Dou, S.X.

2010-01-01

The mechanism of magnetic field sintering on the critical transition temperature, T c , for the Zn doped MgB 2 superconductor was investigated with the observation of Raman scattering measurement and the Raman spectra fit analysis. The broadened E 2g mode in Raman spectra shows the strengthening of the electron-phonon coupling (EPC) for the sample sintered in magnetic field. A synchronous fluctuation is observed between the Raman characters of the E 2g mode and the T c .

Electrodeposition of compact zinc from the hydrophobic Brønsted acidic ionic liquid-based electrolytes and the study of zinc stability along with the acidity manipulation

International Nuclear Information System (INIS)

Chen, Yi-Han; Yeh, Hsin-Wen; Lo, Nai-Chang; Chiu, Chen-Wei; Sun, I-Wen; Chen, Po-Yu

2017-01-01

Highlights: • Compact Zn with no crack is deposited from protic ionic liquid-based electrolytes. • The ionic liquid is composed of the protonated betaine ion. • This ionic liquid is hydrophobic and zinc oxide is soluble in it. • The effects of co-solvents, propylene carbonate and water, are studied. • The Zn stripping/deposition efficiency can be manipulated via acidity adjustment. - Abstract: Compact crystalline zinc was electrodeposited on stainless-steel electrode (SS) via potentiostatic/galvanostatic electrolysis from the hydrophobic Brønsted acidic ionic liquid, protonated betaine bis((trifluoromethyl)sulfonyl)imide (IL [Hbet][TFSI]), −based electrolytes containing ZnCl 2 or ZnO under argon or ambient air atmosphere. Approximate 10 wt% of propylene carbonate and water, respectively, were used as the co-solvents for [Hbet][TFSI] to form the IL-based electrolytes. The efficiency of zinc deposition/stripping, which is significantly affected by the Brønsted acidity of the IL-based electrolytes, was studied at glassy carbon electrode (GC) to evaluate the stability of the zinc electrodeposits along with the electrolyte acidity. The stability is very poor for the zinc electrodeposits obtained from ZnCl 2 solution. However, it increases with increasing the quantity of ZnO or urea in the electrolytes; the former neutralize the dissociable protons in [Hbet] cations to form water, and the latter may form H-bonding with [Hbet] or be protonated to form the weakly acidic cations [HUrea]. Both suppress the reaction between the Zn electrodeposits and protons. The stability of the Zn electrodeposits, therefore, can be improved via the manipulation of the IL acidity.

Long-time tails of time correlation functions for an ionic mixture in a magnetic field and the validity of magnetohydrodynamics

NARCIS (Netherlands)

Suttorp, L.G.

1990-01-01

Mode-coupling theory is used to determine the long-time behaviour of the Green-Kubo integrands for the heat conductivity and the diffusion coefficients of an ionic mixture in a magnetic field. It is shown that the presence of several species of particles with a different ratio of charges and masses

Synthesis of Zn{sub 0.95}Cr{sub 0.05}O DMS by co-precipitation and ceramic methods: Structural and magnetization studies

Energy Technology Data Exchange (ETDEWEB)

Paul Joseph, D. [Materials Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600025 (India); Naveenkumar, S. [Materials Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600025 (India); Sivakumar, N. [Materials Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600025 (India); Venkateswaran, C. [Materials Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600025 (India)]. E-mail: cvunom@hotmail.com

2006-05-10

Transitional metal ions-substituted ZnO are recently explored for SPINTRONICS applications. Synthesis of single-phase oxide 'diluted magnetic semiconductors' (DMS) is a must to explore the magnetic properties arising due to the strong sp-d exchange interaction. The synthesis route plays a vital role in this aspect. In this work, we have prepared Zn{sub 0.95}Cr{sub 0.05}O by using the co-precipitation method and also the standard ceramic method and optimized the conditions to obtain the single-phase compound. X-ray diffraction measurements were done on Zn{sub 0.95}Cr{sub 0.05}O annealed and sintered at various temperatures. Comparing these results, we conclude that the co-precipitation method is more convenient for obtaining single-phase compound by the relatively low temperature processing of the precipitated hydroxides. Pelleted sample examined for its magnetic property using a vibrating sample magnetometer (VSM) indicated ferromagnetic-like behavior at 300 K and a spin-glass state at 77 K.

Using chiral ionic liquid additives to enhance asymmetric induction in a Diels-Alder reaction.

Science.gov (United States)

Goodrich, P; Nimal Gunaratne, H Q; Hall, L; Wang, Y; Jin, L; Muldoon, M J; Ribeiro, A P C; Pombeiro, A J L; Pârvulescu, V I; Davey, P; Hardacre, C

2017-01-31

A bis-oxazoline ligand has been complexed using Cu(ii) and Zn(ii) trifluoromethanesulfonate and a range of chiral ionic liquid (CIL) additives based on natural products were used as a co-catalyst for a Diels-Alder reaction. The catalytic performance of these systems was compared for the asymmetric Diels-Alder reaction between N-acryloyloxazolidinone and cyclopentadiene with and without the presence of a CIL additive. In the absence of the CIL, both catalysts resulted in low enantioselectivities in conventional solvents and ionic liquids. However, whilst only a minor effect of the CIL was observed for the Cu based catalyst, in the case of the Zn based catalyst, significant enhancements in endo enantioselectivity of up to 50% were found on the addition of a CIL.

Effect of surfactant amount on the morphology and magnetic properties of monodisperse ZnFe{sub 2}O{sub 4} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Zhao, Haitao, E-mail: zht95711lunwen@163.com; Liu, Ruiping; Zhang, Qiang; Wang, Qiao

2016-03-15

Graphical abstract: Polyol process to monodisperse ZnFe{sub 2}O{sub 4} nanoparticles. - Highlights: • An one-step, facile and inexpensive synthetic route to monodisperse ZnFe{sub 2}O{sub 4} nanoparticles is described. • The sodium citrate stabilized ZnFe{sub 2}O{sub 4} nanoparticles with a diameter in the 5–8 nm size range can be easily dispersed in water. • The synthesis is very robust in terms of variations of experimental parameters. • ZnFe{sub 2}O{sub 4} nanoparticles present ferrimagnetic behavior at room temperature with a small hysteresis. - Abstract: The spinel ZnFe{sub 2}O{sub 4} ferrites with sodium citrate as a surfactant were fabricated by polyol process. The effect of surfactant amount on the structure, morphology and magnetic properties of ZnFe{sub 2}O{sub 4} ferrites were investigated by X-ray diffraction(XRD), transmission electron microscope (TEM), thermogravimetric and differential scanning calorimetry (TG–DSC) and vibrating sample magnetometry (VSM), respectively. The results indicate that the structure of ZnFe{sub 2}O{sub 4} ferrites is a pure cubic spinel structure with a particle size of 5–8 nm. The dispersion of the synthesized ZnFe{sub 2}O{sub 4} is enhanced when the mole ratio of Fe(acac){sub 3} to sodium citrate decreases. The synthesized particles present ferrimagnetic behavior with a small hysteresis at room temperature. The increase of surfactant amount conversely leads to the decrease in the saturation magnetization value (Ms) especially when the mole ratio of Fe(acac){sub 3} to sodium citrate decreases to 8:3. Its Ms value is drastically reduced to 18.97 emu/g.

Spin-dependent and photon-assisted transmission enhancement and suppression in a magnetic-field tunable ZnSe/Zn{sub 1–x}Mn{sub x}Se heterostructure

Energy Technology Data Exchange (ETDEWEB)

Li, Chun-Lei, E-mail: licl@cnu.edu.cn [Laboratory for Micro-sized Functional Materials, College of Elementary Education, Capital Normal University, Beijing 100048 (China); Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China); Yuan, Rui-Yang [Center for Theoretical Physics, Department of Physics, Capital Normal University, Beijing 100048 (China); Guo, Yong, E-mail: guoy66@tsinghua.edu.cn [Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China); Collaborative Innovation Center of Quantum Matter, Beijing (China)

2016-01-07

Using the effective-mass approximation and Floquet theory, we theoretically investigate the terahertz photon-assisted transport through a ZnSe/Zn{sub 1−x}Mn{sub x}Se heterostructure under an external magnetic field, an electric field, and a spatially homogeneous oscillatory field. The results show that both amplitude and frequency of the oscillatory field can accurately manipulate the magnitude of the spin-dependent transmission probability and the positions of the Fano-type resonance due to photon absorption and emission processes. Transmission resonances can be enhanced to optimal resonances or drastically suppressed for spin-down electrons tunneling through the heterostructure and for spin-up ones tunneling through the same structure, resonances can also be enhanced or suppressed, but the intensity is less than the spin-down ones. Furthermore, it is important to note that transmission suppression can be clearly seen from both the spin-down component and the spin-up component of the current density at low magnetic field; at the larger magnetic field, however, the spin-down component is suppressed, and the spin-up component is enhanced. These interesting properties may provide an alternative method to develop multi-parameter modulation electron-polarized devices.

Structural and magnetic characterization of mixed valence Co(II, III)xZn1−xO epitaxial thin films

International Nuclear Information System (INIS)

Negi, D.S.; Loukya, B.; Dileep, K.; Sahu, R.; Shetty, S.; Kumar, N.; Ghatak, J.; Pachauri, N.; Gupta, A.; Datta, R.

2014-01-01

In this article, we report on the Co atom incorporation, secondary phase formation and composition-dependent magnetic and optical properties of mixed valence Co(II, III) x Zn 1−x O epitaxial thin films grown by pulsed laser deposition. The intended total Co concentration is varied between ∼6–60 at.% with relatively higher concentration of +3 over +2 charge state. Mixed valence Co(II, III) shows high solubility in ZnO (up to 38 at.%) and ferromagnetism is observed in samples with total Co incorporation of ∼29 and 38 at.%. Electron diffraction pattern and high resolution transmission electron microscopy images reveal single crystalline nature of the thin films with wurtzite structure. Co oxide interlayer, with both rock salt and spinel structure, are observed to be formed between the substrate and wurtzite film for total Co concentration at ∼17 at.% and above. Magnetization shows composition dependence with a saturation moment value of ∼93 emu cm −3 and a coercive field of ∼285 Oe observed for ∼38 at.% Co:ZnO films. Ferromagnetism was not observed for films with Co concentration 17 and 9 at.%. The Co oxide interlayer does not show any ferromagnetism. All the films are n-type with carrier concentration ∼10 19 cm −3 . The observed magnetism is probably resulting from direct antiferromagntic exchange interaction between Co 2+ and Co 3+ ions favored by heavy Co alloying giving rise to ferrimagnetism in the system. - Highlights: • Mixed valence Co doped ZnO ferromagnetic single crystal thin film. • Secondary phase formation in terms of CoO and Co3O4 and magnetism is observed only for high Co alloying. • Cathodoluminescence (CL) data showing increase in band gap with Co concentrations

Synthesis, structural investigation and magnetic properties of Zn{sup 2+} substituted cobalt ferrite nanoparticles prepared by the sol–gel auto-combustion technique

Energy Technology Data Exchange (ETDEWEB)

Raut, A.V., E-mail: nano9993@gmail.com [Vivekanand Arts and Sardar Dalipsingh Commerce and Science College, Aurangabad, 431004 Maharastra (India); Barkule, R.S.; Shengule, D.R. [Vivekanand Arts and Sardar Dalipsingh Commerce and Science College, Aurangabad, 431004 Maharastra (India); Jadhav, K.M., E-mail: drjadhavkm@gmail.com [Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad, 431004 Maharastra (India)

2014-05-01

Structural morphology and magnetic properties of the Co{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} (0.0≤x≥1.0) spinel ferrite system synthesized by the sol–gel auto-combustion technique using nitrates of respective metal ions have been studied. The ratio of metal nitrates to citric acid was taken at 1:3. The as prepared powder of cobalt zinc ferrite was sintered at 600 °C for 12 h after TG/DTA thermal studies. Compositional stoichiometry was confirmed by energy dispersive analysis of the X-ray (EDAX) technique. Single phase cubic spinel structure of Co–Zn nanoparticles was confirmed by XRD data. The average crystallite size (t), lattice constant (a) and other structural parameters of zinc substituted cobalt ferrite nanoparticles were calculated from XRD followed by SEM and FTIR. It is observed that the sol–gel auto-combustion technique has many advantages for the synthesis of technologically applicable Co–Zn ferrite nanoparticles. The present investigation clearly shows the effect of the synthesis method and possible relation between magnetic properties and microstructure of the prepared samples. Increase in nonmagnetic Zn{sup 2+} content in cobalt ferrite nanoparticles is followed by decrease in n{sub B}, M{sub s} and other magnetic parameters. Squareness ratio for the Co-ferrite was 1.096 at room temperature. - Highlights: • Co–Zn nanoparticles are prepared by sol–gel auto-combustion method. • Structural properties were characterized by XRD, SEM, and FTIR. • Compositional stoichiometry was confirmed by EDAX analysis. • Magnetic parameters were measured by the pulse field hysteresis loop technique.

Influence of High Magnetic Field and Zn Doping on Robust CO Phase of La0.5Ca0.5MnO3

Science.gov (United States)

Jin, Z.; Xia, Z. C.; Wei, M.; Yang, F.; Huang, S.; Xiao, G. L.; Shang, C.; Cheng, H.; Wu, H.; Zhang, X. X.; Ouyang, Z. W.

2017-08-01

Magnetic and electrical transport properties of La0.5Ca0.5- x Zn x MnO3 ( x = 0, 0.1, 0.15) have been investigated in a wide magnetic field range from 0 T to 50 T. Experimental results show that doping of nonmagnetic Zn2+ ion at Ca site and application of high magnetic field had obvious tuning effects on the stability of the robust charge-order phase, inducing new magnetization and electrical transport behaviors. In particular, obvious temperature and field hysteresis was induced, leading to enhanced magnetoresistance at around room temperature. Based on the intricate interplay between the external magnetic field and chemical strain (lattice distortion) induced by the dopant, which changed the bond length and the angle of double exchange and partially destroyed the charge-order phase, a weak ferromagnetic phase formed. The hysteretic behavior and enhanced magnetoresistance can be understood based on the tuning effects of the high magnetic field and dopant on the stability of the charge-order phase.

Improved ionic conductivity of lithium-zinc-tellurite glass-ceramic electrolytes

Science.gov (United States)

Widanarto, W.; Ramdhan, A. M.; Ghoshal, S. K.; Effendi, M.; Cahyanto, W. T.; Warsito

An enhancement in the secondary battery safety demands the optimum synthesis of glass-ceramics electrolytes with modified ionic conductivity. To achieve improved ionic conductivity and safer operation of the battery, we synthesized Li2O included zinc-tellurite glass-ceramics based electrolytes of chemical composition (85-x)TeO2·xLi2O·15ZnO, where x = 0, 5, 10, 15 mol%. Samples were prepared using the melt quenching method at 800 °C followed by thermal annealing at 320 °C for 3 h and characterized. The effects of varying temperature, alternating current (AC) frequency and Li2O concentration on the structure and ionic conductivity of such glass-ceramics were determined. The SEM images of the annealed glass-ceramic electrolytes displayed rough surface with a uniform distribution of nucleated crystal flakes with sizes less than 1 μm. X-ray diffraction analysis confirmed the well crystalline nature of achieved electrolytes. Incorporation of Li2O in the electrolytes was found to generate some new crystalline phases including hexagonal Li6(TeO6), monoclinic Zn2Te3O8 and monoclinic Li2Te2O5. The estimated crystallite size of the electrolyte was ranged from ≈40 to 80 nm. AC impedance measurement revealed that the variation in the temperatures, Li2O contents, and high AC frequencies have a significant influence on the ionic conductivity of the electrolytes. Furthermore, electrolyte doped with 15 mol% of Li2O exhibited the optimum performance with an ionic conductivity ≈2.4 × 10-7 S cm-1 at the frequency of 54 Hz and in the temperature range of 323-473 K. This enhancement in the conductivity was attributed to the sizable alteration in the ions vibration and ruptures of covalent bonds in the electrolytes network structures.

Ionic cluster size distributions of swollen nafion/sulfated beta-cyclodextrin membranes characterized by nuclear magnetic resonance cryoporometry.

Science.gov (United States)

Jeon, Jae-Deok; Kwak, Seung-Yeop

2007-08-16

Nafion/sb-CD membranes were prepared by mixing 5 wt% Nafion solution with H+-form sulfated beta-cyclodextrin (sb-CD), and their water uptakes, ion exchange capacities (IECs), and ionic cluster size distributions were measured. Gravimetric and thermogravimetric measurements showed that the water uptake of the membranes increased with increases in their sb-CD content. The IECs of the membrane were measured with acid-base titration and found to increase with increases in the sb-CD content, reaching 0.96 mequiv/g for NC5 ("NCx" denotes a Nafion/sb-CD composite membrane containing x wt% of sb-CD). The cluster-correlation peaks and ionic cluster size distributions of the water-swollen membranes were determined using small-angle X-ray scattering (SAXS) and 1H nuclear magnetic resonance (NMR) cryoporometry, respectively. The SAXS experiments confirmed that increases in the sb-CD content of the membranes shifted the maximum SAXS peaks to lower angles, indicating an increase in the cluster correlation peak. NMR cryoporometry is based on the theory of the melting point depression, Delta Tm, of a liquid confined within a pore, which is dependent on the pore diameter. The melting point depression was determined by analyzing the variation of the NMR signal intensity with temperature. Our analysis of the intensity-temperature (IT) curves showed that the ionic cluster size distribution gradually became broader with increases in the membrane sb-CD content due to the increased water content, indicating an increase in the ionic cluster size. This result indicates that the presence of sb-CD with its many sulfonic acid sites in the Nafion membranes results in increases in the ionic cluster size as well as in the water uptake and the IEC. We conclude that NMR cryoporometry provides a method for determining the ionic cluster size on the nanometer scale in an aqueous environment, which cannot be obtained using other methods.

Improved ionic conductivity of lithium-zinc-tellurite glass-ceramic electrolytes

Directory of Open Access Journals (Sweden)

W. Widanarto

Full Text Available An enhancement in the secondary battery safety demands the optimum synthesis of glass-ceramics electrolytes with modified ionic conductivity. To achieve improved ionic conductivity and safer operation of the battery, we synthesized Li2O included zinc-tellurite glass-ceramics based electrolytes of chemical composition (85-xTeO2·xLi2O·15ZnO, where x = 0, 5, 10, 15 mol%. Samples were prepared using the melt quenching method at 800 °C followed by thermal annealing at 320 °C for 3 h and characterized. The effects of varying temperature, alternating current (AC frequency and Li2O concentration on the structure and ionic conductivity of such glass-ceramics were determined. The SEM images of the annealed glass-ceramic electrolytes displayed rough surface with a uniform distribution of nucleated crystal flakes with sizes less than 1 μm. X-ray diffraction analysis confirmed the well crystalline nature of achieved electrolytes. Incorporation of Li2O in the electrolytes was found to generate some new crystalline phases including hexagonal Li6(TeO6, monoclinic Zn2Te3O8 and monoclinic Li2Te2O5. The estimated crystallite size of the electrolyte was ranged from ≈40 to 80 nm. AC impedance measurement revealed that the variation in the temperatures, Li2O contents, and high AC frequencies have a significant influence on the ionic conductivity of the electrolytes. Furthermore, electrolyte doped with 15 mol% of Li2O exhibited the optimum performance with an ionic conductivity ≈2.4 × 10−7 S cm−1 at the frequency of 54 Hz and in the temperature range of 323–473 K. This enhancement in the conductivity was attributed to the sizable alteration in the ions vibration and ruptures of covalent bonds in the electrolytes network structures. Keywords: Zinc-tellurite, Glass-ceramics, X-ray diffraction, Ionic conductivity, Lithium oxide

Magnetic field induced third order susceptibility of third order harmonic generation in a ZnMgSe strained quantum well

Energy Technology Data Exchange (ETDEWEB)

Mark, J. Abraham Hudson, E-mail: a.john.peter@gmail.com; Peter, A. John, E-mail: a.john.peter@gmail.com [Dept. of Physics, SSM Institute of Engineering and Technology, Dindigul-624002 (India)

2014-04-24

Third order susceptibility of third order harmonic generation is investigated in a Zn{sub 0.1}Mg{sub 0.9}Se/Zn{sub 0.8}Mg{sub 0.2}Se/Zn{sub 0.1}Mg{sub 0.9}Se quantum well in the presence of magnetic field strength. The confinement potential is considered as the addition of energy offsets of the conduction band (or valence band) and the strain-induced potential in our calculations. The material dependent effective mass is followed throughout the computation because it has a high influence on the electron energy levels in low dimensional semiconductor systems.

Structural and magnetic properties of nano-sized NiCuZn ferrites synthesized by co-precipitation method with ultrasound irradiation

Energy Technology Data Exchange (ETDEWEB)

Harzali, Hassen, E-mail: harzali@mines-albi.fr [Laboratory of Applied Mineral Chemistry, Faculty of Sciences, University Tunis ElManar, Campus University, Farhat Hached El-Manar, 2092 Tunis (Tunisia); Saida, Fairouz; Marzouki, Arij; Megriche, Adel [Laboratory of Applied Mineral Chemistry, Faculty of Sciences, University Tunis ElManar, Campus University, Farhat Hached El-Manar, 2092 Tunis (Tunisia); Baillon, Fabien; Espitalier, Fabienne [Université de Toulouse, Mines Albi, CNRS, Centre RAPSODEE, Campus Jarlard, F-81013 Albi CT cedex 09 (France); Mgaidi, Arbi [Laboratory of Applied Mineral Chemistry, Faculty of Sciences, University Tunis ElManar, Campus University, Farhat Hached El-Manar, 2092 Tunis (Tunisia); Taibah University, Faculty of Sciences & art, Al Ula (Saudi Arabia)

2016-12-01

Sonochemically assisted co-precipitation has been used to prepare nano-sized Ni–Cu–Zn-ferrite powders. A suspension of constituent hydroxides was ultrasonically irradiated for various times at different temperatures with high intensity ultrasound radiation using a direct immersion titanium horn. Structural and magnetic properties were investigated using X-diffraction (XRD), FT-IR spectroscopy, transmission electron microscopy (TEM), Nitrogen adsorption at 77 K (BET) and Vibrating sample magnetometer (VSM). Preliminary experimental results relative to optimal parameters showed that reaction time t=2 h, temperature θ=90 °C and dissipated Power P{sub diss}=46.27 W. At these conditions, this work shows the formation of nanocrystalline single-phase structure with particle size 10–25 nm. Also, ours magnetic measurements proved that the sonochemistry method has a great influence on enhancing the magnetic properties of the ferrite. - Highlights: • Coprecipitation experiments were carried out with ultrasound. • The spinel ferrite NiCuZn was perfectly synthesized by ultrasound. • The saturation magnetization and crystals size are found to be correlated as the dissipated power was varied.

Structural and magnetic properties of nano-sized NiCuZn ferrites synthesized by co-precipitation method with ultrasound irradiation

International Nuclear Information System (INIS)

Harzali, Hassen; Saida, Fairouz; Marzouki, Arij; Megriche, Adel; Baillon, Fabien; Espitalier, Fabienne; Mgaidi, Arbi

2016-01-01

Sonochemically assisted co-precipitation has been used to prepare nano-sized Ni–Cu–Zn-ferrite powders. A suspension of constituent hydroxides was ultrasonically irradiated for various times at different temperatures with high intensity ultrasound radiation using a direct immersion titanium horn. Structural and magnetic properties were investigated using X-diffraction (XRD), FT-IR spectroscopy, transmission electron microscopy (TEM), Nitrogen adsorption at 77 K (BET) and Vibrating sample magnetometer (VSM). Preliminary experimental results relative to optimal parameters showed that reaction time t=2 h, temperature θ=90 °C and dissipated Power P_d_i_s_s=46.27 W. At these conditions, this work shows the formation of nanocrystalline single-phase structure with particle size 10–25 nm. Also, ours magnetic measurements proved that the sonochemistry method has a great influence on enhancing the magnetic properties of the ferrite. - Highlights: • Coprecipitation experiments were carried out with ultrasound. • The spinel ferrite NiCuZn was perfectly synthesized by ultrasound. • The saturation magnetization and crystals size are found to be correlated as the dissipated power was varied.

Ionic ring current during magnetic disturbances according to observations at geostationary orbit

International Nuclear Information System (INIS)

Vlasova, N.A.; Kovtyukh, A.S.; Panasyuk, M.I.; Sosnovets, Eh.N.; Grafodanskij, O.S.; Islyaev, Sh.N.; Kozlov, A.G.

1988-01-01

Experimental data on variations of H + , (N,O) 2+ and (C,N,O) 4+ flows acquired at communication geostationary satellite GORIZONT (1985-07A) during and after weak magnetic disturbances (with amplitudes of D st -variations which are less than a few tens of nT) are analyzed. Dynamics of ion relative content is investigated. Change of ring current ionic composition within ∼ 50-120 keV/c energy range characterized by the increase of relative content of heavy ions of both solar and ionospheric origin was observed after two weak geomagnetic disturbances on 19-20.02 and 07.03.1985. Examples of disturbances where H + ions and (N,O) 2+ ionospheric ions are the main components of the injected ring current are presented along with the disturbances of such type

Investigating the effects of Co magnetic impurity on optical properties of Zn1-xCoxO

International Nuclear Information System (INIS)

Taghavi mendi, R. A.; Majidiyan, M.; Bouchani, A.; Elahi, M.

2012-01-01

In this paper the effect of Co magnetic impurity on Zn 1-x Co x O in the Wurtzite structure has been studied, and some optical properties such as dielectric function, energy loss function, optical transition, plasmonic energy and refractive index have been calculated with Ab Initio calculations. The results show that adding Co to the compound strongly changes the isotropic features; so that dielectric function and refraction index at low energies are extremely increased. Also, Co has significantly affected the optical transitions . The results of refraction index for pure Zn O are in a good agreement with experimental data.

Magnetic and bioactivity evaluation of ferrimagnetic ZnFe{sub 2}O{sub 4} containing glass ceramics for the hyperthermia treatment of cancer

Energy Technology Data Exchange (ETDEWEB)

Shah, Saqlain A., E-mail: saqlain007pk@hotmail.co [Biomaterials Lab, Department of Physics, GC University Lahore (Pakistan); Hashmi, M.U. [Biomaterials Lab, Department of Physics, GC University Lahore (Pakistan); Alam, S. [PITMAEM, PCSIR Lahore (Pakistan); Shamim, A. [Biomaterials Lab, Department of Physics, GC University Lahore (Pakistan)

2010-02-15

Glass ceramics of the composition xZnO.25Fe{sub 2}O{sub 3}.(40-x)SiO{sub 2}.25CaO.7P{sub 2}O{sub 5}.3Na{sub 2}O were prepared by the melt-quench method using oxy-acetylene flame. Glass-powder compacts were sintered at 1100 deg. C for 3 h and then rapidly cooled at -10 deg. C. X-ray diffraction (XRD) revealed 3 prominent crystalline phases: ZnFe{sub 2}O{sub 4}, CaSiO{sub 3} and Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}. Vibrating sample magnetometer (VSM) data at 10 KOe and 500 Oe showed that saturation magnetization, coercivity and hence hysteresis area increased with the increase in ZnO content. Nano-sized ZnFe{sub 2}O{sub 4} crystallites were of pseudo-single domain structure and thus coercivity increased with the increase in crystallite size. ZnFe{sub 2}O{sub 4} exhibited ferrimagnetism due to the random distribution of Zn{sup 2+} and Fe{sup 3+} cations at tetrahedral A sites and octahedral B sites. This inversion/random distribution of cations was probably due to the surface effects of nano-ZnFe{sub 2}O{sub 4} and rapid cooling of the material from 1100 deg. C (thus preserving the high temperature state of the random distribution of cations). Calorimetric measurements were carried out using magnetic induction furnace at 500 Oe magnetic field and 400 KHz frequency. The data showed that maximum specific power loss and temperature increase after 2 min were 26 W/g and 37 deg. C, respectively for the sample containing 10% ZnO. The samples were immersed in simulated body fluid (SBF) for 3 weeks. Scanning electron microscope (SEM), energy dispersive spectroscopy (EDX) and XRD results confirmed the growth of precipitated hydroxyapatite phase after immersion in SBF, suggesting that the ferrimagnetic glass ceramics were bioactive and could bond to the living tissues in physiological environment.

Investigation of structural, optical, magnetic and electrical properties of tungsten doped Nisbnd Zn nano-ferrites

Science.gov (United States)

Pathania, Abhilash; Bhardwaj, Sanjay; Thakur, Shyam Singh; Mattei, Jean-Luc; Queffelec, Patrick; Panina, Larissa V.; Thakur, Preeti; Thakur, Atul

2018-02-01

Tungsten substituted nickel-zinc ferrite nanoparticles with chemical composition of Ni0.5Zn0.5WxFe2-xO4 (x = 0.0, 0.2, 0.4, 0.6, 0.8 & 1.0) were successfully synthesized by a chemical co-precipitation method. The prepared ferrites were pre sintered at 850 °C and then annealed at 1000 °C in a muffle furnace for 3 h each. This sintered powder was inspected by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and vibrating sample magnetometer (VSM) to study the structural, optical, and magnetic properties. XRD measurement revealed the phase purity of all the nanoferrite samples with cubic spinel structure. The estimated crystallite size by X-ray line broadening is found in the range of 49-62 nm. FTIR spectra of all the samples have observed two prominent absorption bands in the range 400-700 cm-1 arising due to tetrahedral and octahedral stretching vibrations. Vibrating sample magnetometer experiments showed that the saturation magnetizations (MS) decreased with an increase in non-magnetic tungsten ion doping. The electrical resistivity of tungsten doped Nisbnd Zn nano ferrites were examined extensively as a function of temperature. With an increase in tungsten composition, resistivity was found to decrease from 2.2 × 105 Ω cm to 1.9 × 105 Ω cm which indicates the semiconducting behavior of the ferrite samples. The activation energy also decreased from 0.0264 to 0.0221 eV at x = 0.0 to x = 1.0. These low coercive field tungsten doped Nisbnd Zn ferrites are suitable for hyperthermia and sensor applications. These observations are explained in detail on the basis of various models and theories.

Observation of large magnetocaloric effect in equiatomic binary compound ErZn

Directory of Open Access Journals (Sweden)

Lingwei Li

2017-05-01

Full Text Available The magnetism, magnetocaloric effect and universal behaviour in rare earth Zinc binary compound of ErZn have been studied. The ErZn compound undergoes a second order paramagnetic (PM to ferromagnetic (FM transition at Curie temperature of TC ∼ 20 K. The ErZn compound exhibits a large reversible magnetocaloric effect (MCE around its own TC. The rescaled magnetic entropy change curves overlap with each other under various magnetic field changes, further confirming the ErZn with the second order phase transition. For the magnetic field change of 0-7 T, the maximum values of the magnetic entropy change (−ΔSMmax, relative cooling power (RCP and refrigerant capacity (RC for ErZn are 23.3 J/kg K, 581 J/kg and 437 J/kg, respectively.

Sorption of Am(III) on attapulgite/iron oxide magnetic composites. Effect of pH, ionic strength and humic acid

International Nuclear Information System (INIS)

Yu, T.; East China Institute of Technology, Fuzhou, Jiangxi; Fan, Q.H.; Wu, W.S.; Lanzhou Univ., Gansu; Liu, S.P.; Pan, D.Q.; Zhang, Y.Y.; Li, P.

2012-01-01

Attapulgite/iron oxide magnetic (ATP/IOM) composites was prepared, and the sorption behavior of Am(III) on that composites was studied as a function of pH, ionic strength, the solid-to-liquid ratio (m/V), contact time, and the concentration of Am(III) under ambient conditions using batch technique. The time to achieve the sorption equilibrium was less than 5 h. The sorption of Am(III) on ATP/IOM composites was strongly affected by pH and ionic strength. Though ion exchange reaction contributed to Am(III) sorption over low pH range and low ionic strength, the sorption was mainly dominated by surface complexion (i.e., outer- and/or inner-sphere complexes) in the whole observed pH range. In the presence of humic acid (HA), the sorption edge of Am(III) on ATP/IOM composites obviously shifted to lower pH; but Am(III) sorption gradually became weak after pH exceeded 4, which may be mainly in terms of the soluble complexes of HA-Am(III). (orig.)

Ni-Zn Ferrite-graphene Nanohybrids: Synthesis and Characterization of Magnetic and Microwave Absorbing Properties

Directory of Open Access Journals (Sweden)

Thim Ng Yau

2017-01-01

Full Text Available An in-situ deposition technique was used in the synthesis of Ni-Zn ferrite-graphene (NZFG nanohybrids. The XRD patterns revealed the presence of cubic spinel structure of Ni-Zn ferrite (NZF nanoparticles with good crystallinity and small crystallite sizes. The SEM images showed NZF nanoparticles were uniformly deposited on graphene sheets. The effect of different loading amounts of NZF nanoparticles in the nanohybrids was also investigated by tuning the mass ratio of FeCl3 and expanded graphite (EG. The magnetic measurements showed ferromagnetic behaviour with low coercivity. Improvements in saturation magnetization of the nanohybrids can be seen with increasing mass ratio of FeCl3:EG. The microwave absorption properties were determined based on the measured relative complex permittivity and permeability. For the nanohybrids, the minimum reflection loss (RL obtained is -37.57 dB at 7.54 GHz and the absorbing bandwidth in which the RL is less than -10 dB is 7.30 GHz when the NZF content was 79 wt·% at 7 mm thickness. The enhancement in the minimum RL was due to the synergistic effect between NZF nanoparticles and graphene.

Introducing a new and rapid microextraction approach based on magnetic ionic liquids: Stir bar dispersive liquid microextraction

International Nuclear Information System (INIS)

Chisvert, Alberto; Benedé, Juan L.; Anderson, Jared L.; Pierson, Stephen A.; Salvador, Amparo

2017-01-01

With the aim of contributing to the development and improvement of microextraction techniques, a novel approach combining the principles and advantages of stir bar sorptive extraction (SBSE) and dispersive liquid-liquid microextraction (DLLME) is presented. This new approach, termed stir bar dispersive liquid microextraction (SBDLME), involves the addition of a magnetic ionic liquid (MIL) and a neodymium-core magnetic stir bar into the sample allowing the MIL coat the stir bar due to physical forces (i.e., magnetism). As long as the stirring rate is maintained at low speed, the MIL resists rotational (centrifugal) forces and remains on the stir bar surface in a manner closely resembling SBSE. By increasing the stirring rate, the rotational forces surpass the magnetic field and the MIL disperses into the sample solution in a similar manner to DLLME. After extraction, the stirring is stopped and the MIL returns to the stir bar without the requirement of an additional external magnetic field. The MIL-coated stir bar containing the preconcentrated analytes is thermally desorbed directly into a gas chromatographic system coupled to a mass spectrometric detector (TD-GC-MS). This novel approach opens new insights into the microextraction field, by using the benefits provided by SBSE and DLLME simultaneously, such as automated thermal desorption and high surface contact area, respectively, but most importantly, it enables the use of tailor-made solvents (i.e., MILs). To prove its utility, SBDLME has been used in the extraction of lipophilic organic UV filters from environmental water samples as model analytical application with excellent analytical features in terms of linearity, enrichment factors (67–791), limits of detection (low ng L −1 ), intra- and inter-day repeatability (RSD<15%) and relative recoveries (87–113%, 91–117% and 89–115% for river, sea and swimming pool water samples, respectively). - Highlights: • A new microextraction method combining the

Functional ionic liquids

International Nuclear Information System (INIS)

Baecker, Tobias

2012-01-01

In the thesis at hand, new functional ionic liquids were investigated. Main focus was attended to their structure property relations and the structural features leading to a decrease of the melting point. New compounds of the type 1-butyl-3-methylimidazolium tris(N,Ndialkyldithiocarbamato) uranylate with variously substituated dithiocarbamato ligands were synthesized and characterized. Ligands with asymmetrical substitution pattern proved to be most suitable for ionic liquid formation. The single-crystal X-ray structures revealed the interactions in the solid state. Here, the first spectroscopic investigation of the U-S bond in sulfur donated uranyl complexes, up to now only observed in single-crystal X-ray structures, is presented, and the participation of the uranium f-orbitals is shown by theoretical calculations. Electrochemical investigations showed the accessibility of the respective U V O 2 + compounds. As well, ionic liquids with [FeCl 4 ] - and [Cl 3 FeOFeCl 3 ] 2- as anion were synthesized. Both of these anions contain high-spin Fe(III) centres in distorted tetrahedral environment, but exhibit different magnetic behaviour. The tetrachloroferrates show the usual paramagnetism, the m-oxobis(trichloroferrate) exhibits unexpectedly strong antiferromagnetic coupling, as was observed by NMR experiments and susceptibility measurements. To investigate structure-property relations in functionalized ionic liquids, a set of protic, primary alkylammonium and aprotic, quarternary trimethylalkylammonium based ionic liquids was synthesized, and characterized. The length of the alkyl chain was systematically varied, and all compounds were synthesized with and without hydroxyl group, as well as formate and bis(triflyl)amide salts, aiming at getting insight into the influence of the different structure parts on the respective ionic liquid's properties.

Ionic liquid-modified metal sulfides/graphene oxide nanocomposites for photoelectric conversion

International Nuclear Information System (INIS)

Zhang, Yu; Zhang, Yù; Pei, Qi; Feng, Ting; Mao, Hui; Zhang, Wei; Wu, Shuyao; Liu, Daliang; Wang, Hongyu; Song, Xi-Ming

2015-01-01

Graphical abstract: - Highlights: • Metal sulfide (CdS, ZnS, Ag 2 S)/GO nanocomposites were prepared by electrostatic adherence. • Ionic liquid was used to link the metal sulfide and GO in the electrostatic adherence process. • The as-prepared samples showed enhanced photocurrent and highly efficient photocatalytic activity under visible light irradiation. - Abstract: Ionic liquid-modified metal sulfides/graphene oxide nanocomposites are prepared via a facile electrostatic adsorption. Ionic liquid (IL) is firstly used as surface modifier and structure-directing agent of metal sulfide (MS) crystallization process, obtaining ionic liquid modified-MS (IL-MS) nanoparticles with positive charges on surface. IL-MS/GO is obtained by electrostatic adherence between positively charged IL-MS and negatively charged graphene oxide (GO). The as-prepared sample shows enhanced photocurrent and highly efficient photocatalytic activity under visible light irradiation, indicating IL-MS/GO nanocomposites greatly promoted the separation of photogenerated electron–hole pairs

Studies of the magnetic properties of Ni-Zn-Cu ferrite and its synthesis by using metal nitrate salts

International Nuclear Information System (INIS)

Koh, Jae Gui

2004-01-01

Ni-Zn-Cu ferrite was synthesized by decomposing the metal nitrates Ni(NO 3 ) 2 ·6H 2 O, Cu(NO 3 ) 2 ·6H 2 O, Zn(NO 3 ) 2 ·6H 2 O, and Fe(NO 3 ) 3 ·9H 2 O at 200 .deg. C for 20 hours. The ferrite powder was calcined at 400 .deg. C and pulverized for 3, 6, 9, or 12 hours in a steel ball mill. Then, it was sintered from 700 .deg. C to 1000 .deg. C in 100 .deg. C steps for 1 hour at each step. Thus, we could study the effects of the synthesis conditions on the microstructure and magnetic properties of Ni-Zn-Cu ferrite. We could chemically bond initial specimens in liquid at a low-temperature of 150 .deg. C owing to the low melting points, less than 200 .deg. C, of the metal nitrates instead of mechanical ball-mill pulverization, thus narrowing the distance between the particles a molecular one and lowering the sintering point at least by 200 .deg. C to 300 .deg. C. The initial permeability was 50 to 470, and the maximum magnetic induction and coercive force were 0.2410 T and 39.79 A/m to 95.496 A/m, respectively, which are similar to values for Ni-Zn-Cu ferrite synthesized using a conventional process.

Folic acid-functionalized magnetic ZnFe2O4 hollow microsphere core/mesoporous silica shell composite particles: synthesis and application in drug release.

Science.gov (United States)

Yang, Dandan; Wei, Kaiwei; Liu, Qi; Yang, Yong; Guo, Xue; Rong, Hongren; Cheng, Mei-Ling; Wang, Guoxiu

2013-07-01

A drug delivery system was designed by deliberately combining the useful functions into one entity, which was composed of magnetic ZnFe2O4 hollow microsphere as the core, and mesoporous silica with folic acid molecules as the outer shell. Amine groups coated magnetic ZnFe2O4 hollow microsphere core/mesoporous silica shell (MZHM-MSS-NH2) composite particles were first synthesized by a one-pot direct co-condensation method. Subsequently a novel kind of folic acid-functionalized magnetic ZnFe2O4 hollow microsphere core/mesoporous silica shell (MZHM-MSS-NHFA) composite particles were synthesized by conjugating folic acid as targeted molecule to MZHM-MSS-NH2. Ibuprofen, a well-known antiphlogistic drug, was used as a model drug to assess the loading and releasing behavior of the composite microspheres. The results show that the MZHM-MSS-NHFA system has the higher capacity of drug storage and good sustained drug-release property. Copyright © 2013 Elsevier B.V. All rights reserved.

Transparent and flexible quantum dot-polymer composites using an ionic liquid as compatible polymerization medium

International Nuclear Information System (INIS)

Woelfle, Caroline; Claus, Richard O

2007-01-01

Quantum dot (QD)-polymer composites were fabricated based on a solution of QDs dispersed in an ionic liquid. Positively charged water-soluble nanocrystals were obtained from solutions of CdSe/ZnS QDs dispersed in toluene by ligand exchange with 2-dimethylaminoethanethiol (DAET). The resulting QDs were further transferred into a hydrophobic ionic liquid HMITFSI (1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) by cation exchange, resulting in a CdSe/ZnS-HMITFSI solution, which was used as a compatible medium for the polymerization and cross-linking of polymethyl methacrylate networks. Transparent, fluorescent and flexible materials resulted. The quantum yields of the composites depended on the initial properties of the QDs dispersed in toluene, and medium-size QDs (2.6 nm) resulted in the highest quantum yields

Amorphous Al-Mn coating on NdFeB magnets: Electrodeposition from AlCl{sub 3}-EMIC-MnCl{sub 2} ionic liquid and its corrosion behavior

Energy Technology Data Exchange (ETDEWEB)

Chen Jing; Xu Bajin [Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Ling Guoping, E-mail: linggp@zju.edu.cn [Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

2012-06-15

Amorphous Al-Mn coating was electrodeposited on NdFeB magnets from AlCl{sub 3}-EMIC-MnCl{sub 2} ionic liquid with the pretreatment of anodic electrolytic etching in AlCl{sub 3}-EMIC ionic liquid at room temperature. The microstructure, composition and phase constituents of the coatings were investigated by scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The corrosion resistance of the coatings was tested by means of potentiodynamic polarization and immersion test in 3.5 wt. % NaCl solution. The results show that anodic electrolytic etching in AlCl{sub 3}-EMIC ionic liquid is a satisfactory pretreatment to remove the surface oxide film and favor the adhesion of the Al-Mn alloy coating to the NdFeB substrate. The amorphous Al-Mn alloy coating provides sacrificial anodic protection for NdFeB. It exhibited good corrosion resistance and significantly reduced the corrosion current density of NdFeB by three orders of magnitude at potentiodynamic polarization. - Highlights: Black-Right-Pointing-Pointer Amorphous Al-Mn alloy coating was electrodeposited on NdFeB magnet from ionic liquid. Black-Right-Pointing-Pointer To remove the surface oxides of NdFeB, anodic etching pretreatment is used. Black-Right-Pointing-Pointer The deposited Al-Mn alloy coating shows high adhesion to the NdFeB substrate. Black-Right-Pointing-Pointer Corrosion tests show that amorphous Al-Mn alloy coating is anodic coating for NdFeB magnet.

Enhanced photocatalytic performances and magnetic recovery capacity of visible-light-driven Z-scheme ZnFe2O4/AgBr/Ag photocatalyst

Science.gov (United States)

He, Jie; Cheng, Yahui; Wang, Tianzhao; Feng, Deqiang; Zheng, Lingcheng; Shao, Dawei; Wang, Weichao; Wang, Weihua; Lu, Feng; Dong, Hong; Zheng, Rongkun; Liu, Hui

2018-05-01

High efficiency, high stability and easy recovery are three key factors for practical photocatalysts. Z-scheme heterostructure is one of the most promising photocatalytic systems to meet all above requirements. However, efficient Z-scheme photocatalysts which could absorb visible light are still few and difficult to implement at present. In this work, the composite photocatalysts ZnFe2O4/AgBr/Ag were prepared through a two-step method. A ∼92% photodegradation rate on methyl orange was observed within 30 min under visible light, which is much better than that of individual ZnFe2O4 or AgBr/Ag. The stability was also greatly improved compared with AgBr/Ag. The increased performance is resulted from the suitable band alignment of ZnFe2O4 and AgBr, and it is defined as Z-scheme mechanism which was demonstrated by detecting active species and electrochemical impedance spectroscopy. Besides, ZnFe2O4/AgBr/Ag is ferromagnetic and can be recycled by magnet. These results show that ZnFe2O4/AgBr/Ag is a potential magnetically recyclable photocatalyst which can be driven by visible light.

Photoelectrochemical and Raman characterization of nanocrystalline CdS grown on ZnO by successive ionic layer adsorption and reaction method

Energy Technology Data Exchange (ETDEWEB)

Kozytskiy, A.V. [L.V. Pysarzhevsky Institute of Physical Chemistry of National Academy of Sciences of Ukraine, 31 Nauky Av., 03028 Kyiv (Ukraine); Stroyuk, O.L., E-mail: stroyuk@inphyschem-nas.kiev.ua [L.V. Pysarzhevsky Institute of Physical Chemistry of National Academy of Sciences of Ukraine, 31 Nauky Av., 03028 Kyiv (Ukraine); Kuchmiy, S.Ya. [L.V. Pysarzhevsky Institute of Physical Chemistry of National Academy of Sciences of Ukraine, 31 Nauky Av., 03028 Kyiv (Ukraine); Mazanik, A.V.; Poznyak, S.K. [Belarusian State University, Nezalezhnastsi Av. 4, Minsk 220030 (Belarus); Streltsov, E.A., E-mail: streltea@bsu.by [Belarusian State University, Nezalezhnastsi Av. 4, Minsk 220030 (Belarus); Kulak, A.I., E-mail: kulak@igic.bas-net.by [Institute of General and Inorganic Chemistry, National Academy of Sciences of Belarus, Surganova str., 9/1, Minsk 220072 (Belarus); Korolik, O.V. [Belarusian State University, Nezalezhnastsi Av. 4, Minsk 220030 (Belarus); Dzhagan, V.M., E-mail: dzhagan@isp.kiev.ua [V.E. Lashkaryov Institute of Semiconductor Physics of National Academy of Sciences of Ukraine, 41 Nauky Av., 03028 Kyiv (Ukraine)

2014-07-01

Properties of CdS nanoparticles (NPs) grown by successive ionic layer adsorption and reaction (SILAR) method on the surface of electrodeposited ZnO films were studied by Raman, photocurrent and UV–Vis absorption spectroscopies. The CdS nanoparticles deposited at a SILAR cycle number (N) from 5 to 10 exhibit a broadening of the band gap (E{sub g}) by 0.17–0.31 eV as compared with that of the CdS particles grown at N = 30. The size quantization of the interband transition energy in CdS nanoparticles is in accordance with the Raman spectroscopic data demonstrating a considerable increase in the LO peak intensity with increasing the N from 5 to 10 as a result of transition to resonant light scattering. The spectral width of the LO peak decreases from 50 to 15 cm{sup −1} as the N increases from 5 to 30 reflecting a less pronounced effect of the nanoparticle surface on the phonon scattering. A large spectral width of the Raman peaks is assumed to originate from a complex structure of the CdS nanoparticles comprising crystallinity domains that can affect the phonon confinement. The photocurrent spectroscopy of ZnO/CdS heterostructures showed that the band gap of CdS NPs deposited at N > 20 is smaller by ∼ 0.08 eV than that of bulk cadmium sulfide. It was concluded that this effect is not associated with photoexcitation of structural defects but rather reflects intrinsic electronic properties of SILAR-deposited CdS nanoparticles. - Highlights: • Visible-light-sensitive ZnO/CdS heterostructures were prepared by SILAR. • A large Raman peak width originates from a complex structure of CdS nanoparticles. • Vibrational properties of CdS nanoparticles depend on SILAR cycle number.

Photoelectrochemical and Raman characterization of nanocrystalline CdS grown on ZnO by successive ionic layer adsorption and reaction method

International Nuclear Information System (INIS)

Kozytskiy, A.V.; Stroyuk, O.L.; Kuchmiy, S.Ya.; Mazanik, A.V.; Poznyak, S.K.; Streltsov, E.A.; Kulak, A.I.; Korolik, O.V.; Dzhagan, V.M.

2014-01-01

Properties of CdS nanoparticles (NPs) grown by successive ionic layer adsorption and reaction (SILAR) method on the surface of electrodeposited ZnO films were studied by Raman, photocurrent and UV–Vis absorption spectroscopies. The CdS nanoparticles deposited at a SILAR cycle number (N) from 5 to 10 exhibit a broadening of the band gap (E g ) by 0.17–0.31 eV as compared with that of the CdS particles grown at N = 30. The size quantization of the interband transition energy in CdS nanoparticles is in accordance with the Raman spectroscopic data demonstrating a considerable increase in the LO peak intensity with increasing the N from 5 to 10 as a result of transition to resonant light scattering. The spectral width of the LO peak decreases from 50 to 15 cm −1 as the N increases from 5 to 30 reflecting a less pronounced effect of the nanoparticle surface on the phonon scattering. A large spectral width of the Raman peaks is assumed to originate from a complex structure of the CdS nanoparticles comprising crystallinity domains that can affect the phonon confinement. The photocurrent spectroscopy of ZnO/CdS heterostructures showed that the band gap of CdS NPs deposited at N > 20 is smaller by ∼ 0.08 eV than that of bulk cadmium sulfide. It was concluded that this effect is not associated with photoexcitation of structural defects but rather reflects intrinsic electronic properties of SILAR-deposited CdS nanoparticles. - Highlights: • Visible-light-sensitive ZnO/CdS heterostructures were prepared by SILAR. • A large Raman peak width originates from a complex structure of CdS nanoparticles. • Vibrational properties of CdS nanoparticles depend on SILAR cycle number

Origin of Nanobubbles Electrochemically Formed in a Magnetic Field: Ionic Vacancy Production in Electrode Reaction

Science.gov (United States)

Aogaki, Ryoichi; Sugiyama, Atsushi; Miura, Makoto; Oshikiri, Yoshinobu; Miura, Miki; Morimoto, Ryoichi; Takagi, Satoshi; Mogi, Iwao; Yamauchi, Yusuke

2016-07-01

As a process complementing conventional electrode reactions, ionic vacancy production in electrode reaction was theoretically examined; whether reaction is anodic or cathodic, based on the momentum conservation by Newton’s second law of motion, electron transfer necessarily leads to the emission of original embryo vacancies, and dielectric polarization endows to them the same electric charge as trans- ferred in the reaction. Then, the emitted embryo vacancies immediately receive the thermal relaxation of solution particles to develop steady-state vacancies. After the vacancy production, nanobubbles are created by the collision of the vacancies in a vertical magnetic field.

Improve the open-circuit voltage of ZnO solar cells with inserting ZnS layers by two ways

International Nuclear Information System (INIS)

Sun, Yunfei; Yang, Jinghai; Yang, Lili; Cao, Jian; Gao, Ming; Zhang, Zhiqiang; Wang, Zhe; Song, Hang

2013-01-01

ZnS NPs layers were deposited on ZnO NRs by two different ways. One is spin coating; the other is successive ionic layer adsorption and reaction (SILAR) method. The ZnO NRs/ZnS NPs composites were verified by X-ray diffraction, X-ray photoelectron spectroscopy, and UV–visible spectrophotometer; their morphologies and thicknesses were examined by scanning electron microscopic and transmission electron microscopic images. The CdS quantum dot sensitized solar cells (QDSSCs) were constructed using ZnO NRs/ZnS NPs composites as photoanode and their photovoltaic characteristic was studied by J–V curves. The results indicated that the way of SILAR is more beneficial for retarding the back transfer of electrons to CdS and electrolyte than spin coating method. The open-circuit voltage increased to 0.59 V by introducing a ZnS layer through SILAR method. When ZnS NPs layer was deposited for 10 times on ZnO NRs, the conversion efficiency of QDSSC shows ∼3.3 folds increments of as-synthesized ZnO solar cell. - Graphical abstract: When ZnO nanorods were deposited by ZnS for 10 times, the conversion efficiency of QDSSC shows ∼3.3 folds increments of as-synthesized ZnO solar cell. Highlights: ► ZnS layers were deposited with two different ways. ► The way of SILAR is more beneficial for retarding the back transfer of electrons. ► The open-circuit voltage increased to 0.59 V by introducing a ZnS layer through SILAR method

Improve the open-circuit voltage of ZnO solar cells with inserting ZnS layers by two ways

Energy Technology Data Exchange (ETDEWEB)

Sun, Yunfei [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Yang, Jinghai, E-mail: jhyang1@jlnu.edu.cn [Institute of Condensed State Physics, Jilin Normal University, Siping 136000 (China); Yang, Lili; Cao, Jian [Institute of Condensed State Physics, Jilin Normal University, Siping 136000 (China); Gao, Ming [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Institute of Condensed State Physics, Jilin Normal University, Siping 136000 (China); Zhang, Zhiqiang; Wang, Zhe [Institute of Condensed State Physics, Jilin Normal University, Siping 136000 (China); Song, Hang [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China)

2013-04-15

ZnS NPs layers were deposited on ZnO NRs by two different ways. One is spin coating; the other is successive ionic layer adsorption and reaction (SILAR) method. The ZnO NRs/ZnS NPs composites were verified by X-ray diffraction, X-ray photoelectron spectroscopy, and UV–visible spectrophotometer; their morphologies and thicknesses were examined by scanning electron microscopic and transmission electron microscopic images. The CdS quantum dot sensitized solar cells (QDSSCs) were constructed using ZnO NRs/ZnS NPs composites as photoanode and their photovoltaic characteristic was studied by J–V curves. The results indicated that the way of SILAR is more beneficial for retarding the back transfer of electrons to CdS and electrolyte than spin coating method. The open-circuit voltage increased to 0.59 V by introducing a ZnS layer through SILAR method. When ZnS NPs layer was deposited for 10 times on ZnO NRs, the conversion efficiency of QDSSC shows ∼3.3 folds increments of as-synthesized ZnO solar cell. - Graphical abstract: When ZnO nanorods were deposited by ZnS for 10 times, the conversion efficiency of QDSSC shows ∼3.3 folds increments of as-synthesized ZnO solar cell. Highlights: ► ZnS layers were deposited with two different ways. ► The way of SILAR is more beneficial for retarding the back transfer of electrons. ► The open-circuit voltage increased to 0.59 V by introducing a ZnS layer through SILAR method.

Magnetic Properties of NdFe10Mo2-N Bonded Magnet

Science.gov (United States)

Zhang, Hong-Wei; Hu, Bo-Ping; Han, Zhong-Fan; Jin, Han-Min; Fu, Quan

1997-06-01

The dependence of remanence and coercivity on the magnetizing field is studied for isotropic and anisotropic epoxy resin bonded magnets. It was found that the coercivity of the NdFe10Mo2-N bonded magnet is mainly controlled by nucleation of reversed magnetic domains. Variation of iHc with Zn content and heat treatment conditions is studied. The value of 0 iHc obtained in the best Zn-bonded condition is about 0.15 T higher than before bonding. The variation of the amount of α-Fe with processing conditions is demonstrated for anisotropic Zn-bonded magnets.

Preparation of cytocompatible luminescent and magnetic nanohybrids based on ZnO, Zn{sub 0.95}Ni{sub 0.05}O and core-shell ZnO-Fe{sub 2}O{sub 3} polymer grafted nanoparticles for biomedical imaging

Energy Technology Data Exchange (ETDEWEB)

Balti, I., E-mail: Imenbalti12@yahoo.fr [Universite de Carthage, Departement de Chimie, Unite de recherche UR11ES30, Faculte des sciences de Bizerte (Tunisia); Barrere, A., E-mail: amelie.barrere@univ-paris13.fr; Gueguen, V., E-mail: virginie.gueguen@univ-paris13.fr; Poussard, L., E-mail: loic.poussard@materianova.be; Pavon-Djavid, G., E-mail: graciela.pavon@univ-paris13.fr; Meddahi-Pelle, A., E-mail: anne.pelle@inserm.fr [Universite Paris 13, Laboratoire de bio-ingenierie des polymeres cardiovasculaires, Inserm U698, Institut Galilee (France); Rabu, P., E-mail: pierre.rabu@ipcms.unistra.fr [Departement de Chimie des Materiaux Inorganiques, IPCMS UMR7504, CNRS-UDS, 23 (France); Smiri, L. S., E-mail: lsmiri@gmail.com [Universite de Carthage, Departement de Chimie, Unite de recherche UR11ES30, Faculte des sciences de Bizerte (Tunisia); Jouini, N., E-mail: jouini@univ-paris13.fr [Universite Paris 13, Laboratoire de Sciences des Procedes et des Materiaux, LSPM, CNRS UPR 3407, Institut Galilee (France); Chaubet, F., E-mail: frederic.chaubet@univ-paris13.fr [Universite Paris 13, Laboratoire de bio-ingenierie des polymeres cardiovasculaires, Inserm U698, Institut Galilee (France)

2012-12-15

ZnO, Zn{sub 0.95}Ni{sub 0.05}O and core-shell ZnO-{gamma}-Fe{sub 2}O{sub 3} nanoparticles (NPs) have been prepared by forced hydrolysis in polyol medium and then coated via the 'grafting from' approach with poly(sodium-4-styrenesulfonate) and poly(sodium-4-styrenesulfonate-co-sodium methacrylate) in the case of ZnO. The surface-initiated atom transfer radical polymerization occurred from the surface-functionalized NPs with {alpha}-bromoisobutyric acid as initiator. The polymer chains were grown from the surface to yield hybrid NPs with a 1-3-nm thick organic shell. FT-IR, TGA and electron microscopy evidenced the presence of a polymer layer on the surface of NPs. Magnetic and optical properties of bare and coated NPs have been measured. Eventually, the weak cytotoxicity of coated NPs on human endothelial cell allows considering their potentialities as new tools for nanomedicine and biomedical imaging.

Spin canting and magnetic transition in NixZn1-xFe2O4 (x=0.0, 0.5 and 1.0) nanoparticles

Science.gov (United States)

Rani, Stuti; Raghav, Dharmendra Singh; Yadav, Prashant; Varma, G. D.

2018-04-01

Nanoparticles of NixZn1-xFe2O4(x=0.0, 0.5 and 1.0) have been synthesized via co-precipitation method and studied thestructural and magnetic properties. Rietveld refinement of X ray diffraction data of as synthesized samples revealthat the samples have mixed spinel structure with space group Fd-3m. The lattice parameter of the samples decreases as doping concentration of Ni ions increases. Magnetic measurements show paramagnetic to ferrimagnetic transition at room temperature on Ni doping in ZnFe2O4 nanoparticles. The magnetic measurements also show spin canting in samples possibly due to their nanocrystalline nature. The spin canting angles have been calculated with the help of Yafet-Kittel (Y-K) model. Furthermore, the Law of approach (LA) fitting of M-H curves indicates that the samples are highly anisotropicin nature. The Arrot plots of as synthesized samples also indicate the paramagnetic to ferrimagnetic transition. The correlation between the structural and observed magnetic properties of NixZn1-xFe2O4(x=0.0, 0.5 and 1.0) nanocrystals will be described and discussed in this paper.

Successive ionic layer adsorption and reaction deposited kesterite Cu{sub 2}ZnSnS{sub 4} nanoflakes counter electrodes for efficient dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Mali, Sawanta S.; Shim, Chang Su; Hong, Chang Kook, E-mail: hongck@chonnam.ac.kr

2014-11-15

Highlights: • Cu{sub 2}ZnSnS{sub 4} nanoflakes by SILAR technique. • Hydrothermal synthesis of TiO{sub 2}. • Counter electrode for DSSC application. • 4.48% conversion efficiency. - Abstract: In this investigation, we have successfully synthesized Cu{sub 2}ZnSnS{sub 4} (CZTS) nanoflakes by successive ionic layer adsorption and reaction (SILAR) method and used as a counter electrode in the hydrothermally grown TiO{sub 2} based dye sensitized solar cells (DSSCs). The prepared CZTS nanoflakes were characterized using X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), micro Raman spectroscopy and energy dispersive analysis. Our DSSCs results revealed that, compared with conventional Pt/FTO counter electrode DSSCs, nanoflakes of p-type CZTS as the photocathode and n-type TiO{sub 2} thin films as the photoanode shows an increased short circuit current (13.35 mA/cm{sup 2}) with 4.84% power conversion efficiency. The detailed interface properties of were analyzed by electrochemical impedance spectroscopy (EIS) measurements.

Structural, magnetic and electrical properties of Zr-substitued NiZnCo ferrite nanopowders

Energy Technology Data Exchange (ETDEWEB)

Li, Le-Zhong, E-mail: lezhongli@cuit.edu.cn; Zhong, Xiao-Xi; Wang, Rui; Tu, Xiao-Qiang

2017-08-01

Highlights: • The static magnetic properties of NiZnCoZr ferrite nanopowders have been investigated. • The dielectric constant increases with the increase of Zr substitution. • The relaxation peak of tan δ ∼ T curves is observed for x ≥ 0.10. • Electrical transport behavior is found to follow the impurity semiconductor. • The dc resistivity increases at transition temperature with Zr substitution. - Abstract: Zr-substituted NiZnCo ferrite nanopowders, Ni{sub 0.4−x}Zn{sub 0.5}Zr{sub x}Co{sub 0.1}Fe{sub 2.0}O{sub 4} (0 ≤ x ≤ 0.20), were synthesized by the sol-gel auto-combustion method. The effects of Zr substitution on the structural, magnetic and electrical properties have been investigated. The DTA and TG results indicate that there are three steps of combustion process. The X-ray diffraction patterns show that the lattice parameter and the average crystallite size increase with the increase of Zr substitution. The saturation magnetization increases with the increase of Zr substitution when x ≤ 0.05, and then decreases when x > 0.05. Meanwhile, the coercivity initially decreases with the increase of Zr substitution when x ≤ 0.05, and then increases when x > 0.05. The polarization behavior for all the samples in the test frequency range from100 Hz to10 MHz obeys the charge polarization mechanism, which happens since the frequency of the hopping of electron exchange between Fe{sup 2+} and Fe{sup 3+} ions are far from the frequency of alternating-current field. And the dielectric constant increases with the increase of Zr substitution. The relaxation peak of the frequency dependence of dielectric loss is observed for x ≥ 0.10, which is due to the frequency of charge hopping between the Fe{sup 2+} and Fe{sup 3+} exactly matches with the frequency of the external applied field. Electrical transport behavior of the ferrite nanopowders is found to follow the impurity semiconductor, and the effect of Zr substitution on the temperature dependence

Magnetic properties of Mn-doped ZnO diluted magnetic semiconductors

International Nuclear Information System (INIS)

Liu Xuechao; Zhang Huawei; Zhang Tao; Chen Boyuan; Chen Zhizhan; Song Lixin; Shi Erwei

2008-01-01

A series of Mn-doped ZnO films have been prepared in different sputtering plasmas by using the inductively coupled plasma enhanced physical vapour deposition. The films show paramagnetic behaviour when they are deposited in an argon plasma. The Hall measurement indicates that ferromagnetism cannot be realized by increasing the electron concentration. However, the room-temperature ferromagnetism is obtained when the films are deposited in a mixed argon-nitrogen plasma. The first-principles calculations reveal that antiferromagnetic ordering is favoured in the case of the substitution of Mn 2+ for Zn 2+ without additional acceptor doping. The substitution of N for O (N O −) is necessary to induce ferromagnetic couplings in the Zn-Mn-O system. The hybridization between N 2p and Mn 3d provides an empty orbit around the Fermi level. The hopping of Mn 3d electrons through the empty orbit can induce the ferromagnetic coupling. The ferromagnetism in the N-doped Zn-Mn-O system possibly originates from the charge transfer between Mn 2+ and Mn 3+ via N O − . The key factor is the empty orbit provided by substituting N for O, rather than the conductivity type or the carrier concentration

Binder-free ZnO@ZnSnO3 quantum dots core-shell nanorod array anodes for lithium-ion batteries

Science.gov (United States)

Tan, Hsiang; Cho, Hsun-Wei; Wu, Jih-Jen

2018-06-01

In this work, ZnSnO3 quantum dots (QDs), instead of commonly used conductive carbon, are grown on the ZnO nanorod (NR) array to construct the binder-free ZnO@ZnSnO3 QDs core-shell NR array electrode on carbon cloth for lithium-ion battery. The ZnO@ZnSnO3 QDs core-shell NR array electrode exhibits excellent lithium storage performance with an improved cycling performance and superior rate capability compared to the ZnO NR array electrode. At a current density of 200 mAg-1, 15.8% capacity loss is acquired in the ZnO@ZnSnO3 QDs core-shell NR array electrode after 110 cycles with capacity retention of 1073 mAhg-1. Significant increases in reversible capacities from 340 to 545 mAhg-1 and from 95 to 390 mAhg-1 at current densities of 1000 and 2000 mAg-1, respectively, are achieved as the ZnO NR arrays are coated with the ZnSnO3 QD shells. The remarkably improved electrochemical performances result from that the configuration of binder-free ZnO@ZnSnO3 QDs core-shell NR array electrode not only facilitates the charge transfer through the solid electrolyte interface and the electronic/ionic conduction boundary as well as lithium ion diffusion but also effectively accommodates the volume change during repeated charge/discharge processes.