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Sample records for synthesis magnetic properties

  1. Barium hexaferrite nanoparticles: Synthesis and magnetic properties

    International Nuclear Information System (INIS)

    Martirosyan, K.S.; Galstyan, E.; Hossain, S.M.; Wang Yiju; Litvinov, D.

    2011-01-01

    Carbon combustion synthesis is applied to rapid and energy efficient fabrication of crystalline barium hexaferrite nanoparticles with the average particle size of 50-100 nm. In this method, the exothermic oxidation of carbon nanoparticles with an average size of 5 nm with a surface area of 80 m 2 /g generates a self-propagating thermal wave with maximum temperatures of up to 1000 deg. C. The thermal front rapidly propagates through the mixture of solid reactants converting it to the hexagonal barium ferrite. Carbon is not incorporated in the product and is emitted from the reaction zone as a gaseous CO 2 . The activation energy for carbon combustion synthesis of BaFe 12 O 19 was estimated to be 98 kJ/mol. A complete conversion to hexagonal barium ferrite is obtained for carbon concentration exceeding 11 wt.%. The magnetic properties H c ∼3000 Oe and M s ∼50.3 emu/g of the compact sintered ferrites compare well with those produced by other synthesis methods.

  2. 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

  3. Magnetic nanoparticles: synthesis, ordering and properties

    International Nuclear Information System (INIS)

    Vazquez, M.; Luna, C.; Morales, M.P.; Sanz, R.; Serna, C.J.; Mijangos, C.

    2004-01-01

    Polyol methods to synthesize nanoparticles and their arrays are firstly described. Magnetic nanoparticles self-assemble under particular conditions into spherical superstructures, like CoNi nanoparticles, or planar structures with hexagonal ordering, like FePt nanoparticles. Particles and their arrays are structurally analysed by techniques like TEM, X-ray, etc. Magnetic characterization is firstly performed by VSM magnetomer as a function of the nanoparticles size paying particular attention to the transition from multidomain to single-domain structures. Later on, magnetic exchange coupling effects are discussed including the temperature dependence of magnetic parameters as coercive and exchange bias fields, as well as the influence of field or zero-field cooling processes. Finally, magnetic polymers consisting of magnetic nanoparticles embedded into PVC polymeric matrix are prepared and magnetically analysed

  4. Synthesis, magnetic and microstructural properties of Alnico magnets with additives

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Zubair, E-mail: dza.isit@yahoo.com [School of Materials Science and Engineering, South China, University of Technology, Guangzhou 510640 (China); Liu, Zhongwu [School of Materials Science and Engineering, South China, University of Technology, Guangzhou 510640 (China); Ul Haq, A. [Riphah International University, I-14, Islamabad (Pakistan)

    2017-04-15

    The phase formation, crystal structure, crystallographic texture, microstructure and magnetic properties of Alnico-8 alloys with varying Co and Nb content have been investigated and presented. Alnico-8 alloys were fabricated by induction melting and casting techniques. Magnetic properties in the alloys were induced by optimized thermomagnetic treatment and subsequent aging. The 37.9Fe-32Co-14Ni-7.5Al-3.1Cu-5.5Ti alloy exhibits coercivity of 110 kA/m, remanence of 0.66 T and energy product of 31.2 kJ/m{sup 3}. The addition of 35 wt% Co in conjunction with 1.5 wt% Nb to 37.9Fe-14Ni-7.5Al-3.1Cu-5.5Ti alloys led to increase the magnetic properties, especially coercivity. The enhancement of the coercivity is attributed to ideal shape anisotropy and optimum mass fraction of ferromagnetic Fe-Co rich particles, which are 25–30 nm in diameter and 300–350 nm in length. The 33.4Fe-35Co-14Ni-7.5Al-5.5Ti-3.1Cu-1.5 Nb alloy yields the optimum magnetic properties of coercivity of 141.4 kA/m, remanence of 0.83 T and energy product of 42.4 kJ/m{sup 3}. The good magnetic properties in the studied alloys are attributed to the nanostructured microstructure comprising textured Fe-Co-Nb rich α{sub 1} phase and Al-Ni-Cu rich α{sub 2} phase. - Highlights: • Synthesize of Alnico-8 magnets by casting and thermomagnetic treatment. • High coercivity up to 148.3 kA/m can be obtained with Alnico magnets. • Properties are affected by intrinsic properties of spinodal phases and thermal cycle. • Magnet exhibits properties as: H{sub c}=141.4 kA/m, B{sub r}=0.83 T and (BH){sub max}=42.4 kJ/m{sup 3}.

  5. Synthesis and magnetic properties of tin spinel ferrites doped manganese

    Science.gov (United States)

    El Moussaoui, H.; Mahfoud, T.; Habouti, S.; El Maalam, K.; Ben Ali, M.; Hamedoun, M.; Mounkachi, O.; Masrour, R.; Hlil, E. K.; Benyoussef, A.

    2016-05-01

    In this work we report the synthesis, the microstructural characterization and the magnetic properties of tin spinel ferrites doped manganese (Sn1-xMnxFe2O4 with x=0.25, 0.5, 0.75, and 1) nanoparticles prepared by co-precipitation method. The effect of annealing temperature on the structure, morphology and magnetic properties of Sn0.5Mn0.5Fe2O4 has been investigated. The synthesized nanoparticle sizes have been controlled between 4 and 9 nm, with uniform spherical morphology as confirmed by transmission electron microscopy (TEM). All the samples prepared possess single domain magnetic. The nanoparticles of Sn0.5Mn0.5Fe2O4 with 4 nm in diameter have a blocking temperature close to 100 K. In addition, the cation distribution obtained from the X-ray diffraction of this sample was confirmed by magnetic measurement. For the Sn1-xMnxFe2O4; (0≤x≤1) samples, the magnetization and coercive fields increase when the augmentation of Mn content increases. For x=0.5, such parameters decrease when the calcination temperature increases.

  6. Synthesis and magnetic properties of tin spinel ferrites doped manganese

    Energy Technology Data Exchange (ETDEWEB)

    El Moussaoui, H., E-mail: elmoussaoui.hassan@gmail.com [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Mahfoud, T.; Habouti, S. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); El Maalam, K.; Ben Ali, M. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Laboratoire of Magnetism and the Physics of the high Energies, URAC 12, Departement of physique, B.P. 1014, Faculty of science, Mohammed V University, Rabat (Morocco); Hamedoun, M.; Mounkachi, O. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Masrour, R. [Laboratory of Materials, Processes, Environment and Quality, Cady Ayyed University, National School of Applied Sciences, Route Sidi Bouzid – BP 63, 46000 Safi (Morocco); Hlil, E.K. [Institut Néel, CNRS-UJF, B.P. 166, 38042 Grenoble Cedex (France); Benyoussef, A. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Laboratoire of Magnetism and the Physics of the high Energies, URAC 12, Departement of physique, B.P. 1014, Faculty of science, Mohammed V University, Rabat (Morocco); Hassan II Academy of Science and Technology, Rabat (Morocco)

    2016-05-01

    In this work we report the synthesis, the microstructural characterization and the magnetic properties of tin spinel ferrites doped manganese (Sn{sub 1−x}Mn{sub x}Fe{sub 2}O{sub 4} with x=0.25, 0.5, 0.75, and 1) nanoparticles prepared by co-precipitation method. The effect of annealing temperature on the structure, morphology and magnetic properties of Sn{sub 0.5}Mn{sub 0.5}Fe{sub 2}O{sub 4} has been investigated. The synthesized nanoparticle sizes have been controlled between 4 and 9 nm, with uniform spherical morphology as confirmed by transmission electron microscopy (TEM). All the samples prepared possess single domain magnetic. The nanoparticles of Sn{sub 0.5}Mn{sub 0.5}Fe{sub 2}O{sub 4} with 4 nm in diameter have a blocking temperature close to 100 K. In addition, the cation distribution obtained from the X-ray diffraction of this sample was confirmed by magnetic measurement. For the Sn{sub 1−x}Mn{sub x}Fe{sub 2}O{sub 4}; (0≤x≤1) samples, the magnetization and coercive fields increase when the augmentation of Mn content increases. For x=0.5, such parameters decrease when the calcination temperature increases. - Highlights: • We have studied the microstructural and the magnetic properties of Sn{sub 1-x}MnxFe{sub 2}O{sub 4}. • The nanoparticles of Sn{sub 0.5}Mn{sub 0.5}Fe{sub 2}O{sub 4} have a blocking temperature around 100 K. • The Ms and Hc increase with the augmentation of Mn content.

  7. Anisotropic nanomaterials: Synthesis, optical and magnetic properties, and applications

    Science.gov (United States)

    Banholzer, Matthew John

    As nanoscience and nanotechnology mature, anisotropic metal nanostructures are emerging in a variety of contexts as valuable class of nanostructures due to their distinctive attributes. With unique properties ranging from optical to magnetic and beyond, these structures are useful in many new applications. Chapter two discusses the nanodisk code: a linear array of metal disk pairs that serve as surface-enhanced Raman scattering substrates. These multiplexing structures employ a binary encoding scheme, perform better than previous nanowires designs (in the context of SERS) and are useful for both convert encoding and tagging of substrates (based both on spatial disk position and spectroscopic response) as well as biomolecule detection (e.g. DNA). Chapter three describes the development of improved, silver-based nanodisk code structures. Work was undertaken to generate structures with high yield and reproducibility and to reoptimize the geometry of each disk pair for maximum Raman enhancement. The improved silver structures exhibit greater enhancement than Au structures (leading to lower DNA detection limits), convey additional flexibility, and enable trinary encoding schemes where far more unique structures can be created. Chapter four considers the effect of roughness on the plasmonic properties of nanorod structures and introduces a novel method to smooth the end-surfaces of nanorods structures. The smoothing technique is based upon a two-step process relying upon diffusion control during nanowires growth and selective oxidation after each step of synthesis is complete. Empirical and theoretical work show that smoothed nanostructures have superior and controllable optical properties. Chapter five concerns silica-encapsulated gold nanoprisms. This encapsulation allows these highly sensitive prisms to remain stable and protected in solution, enabling their use as class-leading sensors. Theoretical study complements the empirical work, exploring the effect of

  8. Synthesis of FeCo magnetic nanoalloys and investigation of heating properties for magnetic fluid hyperthermia

    Science.gov (United States)

    Çelik, Özer; Fırat, Tezer

    2018-06-01

    In this study, size controlled FeCo colloidal magnetic nanoalloys in the range of 11.5-37.2 nm were synthesized by surfactant assistant ball milling method. Magnetic separation technique was performed subsequent to synthesis process so as to obtain magnetic nanoalloy fluid with narrow size distribution. Particle distribution was determined by transmission electron microscope (TEM) while X-ray diffraction (XRD) measurements verified FeCo alloy formation as BCC structure. Vibrating sample magnetometer (VSM) method was used to investigate magnetic properties of nanoalloys. Maximum saturation magnetization and maximum coercivity were obtained as 172 Am2/kg for nanoparticles with the mean size of 37.2 nm and 19.4 mT for nanoparticles with the mean size of 13.3 nm, respectively. The heating ability of FeCo magnetic nanoalloys was determined through calorimetrical measurements for magnetic fluid hyperthermia (MFH) applications. Heat generation mechanisms were investigated by using linear response theory and Stoner-Wohlfarth (S-W) model. Specific absorption rate (SAR) values were obtained in the range of 2-15 W/g for magnetic field frequency of 171 kHz and magnetic field strength in between 6 and 14 mT.

  9. Synthesis, characterization and magnetic properties of Fe-Al nanopins

    International Nuclear Information System (INIS)

    Zhang, W.S.; Brueck, E.; Li, W.F.; Si, P.Z.; Geng, D.Y.; Zhang, Z.D.

    2005-01-01

    We report the synthesis of Fe-Al nanopins using arc discharge. The morphology and chemical composition of the Fe-Al nanopins were studied by means of X-ray diffraction, X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), and high-resolution transmission electron microscopy (HRTEM). The nanopins are composed of a spherical base of about 20-100 nm and a needle-like tip of about several hundred nanometers. EDX and HRTEM studies indicate that the spherical base is mainly composed of α-Fe and FeAl core coated with a thin Al 2 O 3 layer, while the needle-like part contains only Al and O and corresponds to Al 2 O 3 . The formation mechanism of the nanopins is suggestive of a vapor-liquid-solid (VLS) growth process. The as-prepared Fe-Al nanopins show ferromagnetic properties. The temperature dependence of the magnetization at high temperatures indicates the existence of some phase transformations

  10. Synthesis, thermal and magnetic properties of RE-diborides

    Energy Technology Data Exchange (ETDEWEB)

    Novikov, V.V., E-mail: vvnovikov@mail.ru [Training-Research Center ' Bryansk Physical Laboratory' , Petrovsky Bryansk State University, 14, Bezhitskaya St, 241036 Bryansk (Russian Federation); Matovnikov, A.V. [Training-Research Center ' Bryansk Physical Laboratory' , Petrovsky Bryansk State University, 14, Bezhitskaya St, 241036 Bryansk (Russian Federation); Volkova, O.S. [Lomonosov Moscow State University, GSP-1, Leninskie Gory, 119991 Moscow (Russian Federation); Vasil' ev, A.N., E-mail: vasil@mig.phys.msu.ru [Lomonosov Moscow State University, GSP-1, Leninskie Gory, 119991 Moscow (Russian Federation)

    2017-04-15

    Techniques of synthesis of RE diborides (RB{sub 2}) are developed (R=Tb, Dy, Ho, Er, Lu). Temperature dependence of magnetisation, a heat capacity, a lattice parameters of diborides in the range of 2–300 K are measured. According to joint calorimetric and X-ray research the analysis of a phonon component of a heat capacity and thermal expansion of RE-diborides is carried out by Debye-Einstein's models, the parameters of the model are determined. The change of magnetisation of the ferromagnetic RB{sub 2} compounds with growth of temperature caused by violation of ordering in the system of the atomic magnetic moments is compared with the change of entropy of a magnetic subsystem calculated from calorimetric data. Analytical expansion for calculation of a magnetic component of a heat capacity by RB{sub 2} magnetisation data at the temperatures of 2–300 K is obtained. - Highlights: • 1 Techniques of synthesis of RE diborides (RB{sub 2}) are developed (R=Tb, Dy, Ho, Er, Lu). • 2 Temperature dependence of magnetisation of diborides at 2–300 K is determined. • 3 Calculation method of RB{sub 2} magnetic heat capacity from magnetic data is obtained.

  11. The impact of the chemical synthesis on the magnetic properties of intermetallic PdFe nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Castellanos-Rubio, I.; Insausti, M.; Muro, I. Gil de [Universidad del País Vasco, UPV/EHU, Dpto. de Química Inorgánica (Spain); Arias-Duque, D. Carolina; Hernández-Garrido, Juan Carlos [Universidad de Cadiz, Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Facultad de Ciencias (Spain); Rojo, T.; Lezama, L., E-mail: luis.lezama@ehu.es [Universidad del País Vasco, UPV/EHU, Dpto. de Química Inorgánica (Spain)

    2015-05-15

    Palladium-rich Iron nanoparticles in the 4–8 nm range have been produced by a combination of two methods: the thermal decomposition of organometallic precursors and the reduction of metallic salts by a polyol. Herein, it is shown how the details of the synthesis have a striking impact on the magnetic and morphological properties of the final products. In the synthesis of these bimetallic nanoparticles, the use of high reaction temperatures plays an essential role in attaining good chemical homogeneity, which has proved to have a key influence on the magnetic properties. Magnetic characterization has been performed by electron magnetic resonance and magnetization measurements, which have confirmed the superparamagnetic-like behavior at room temperature. No clear traces of magnetic polarization in palladium atoms have been detected. The combination of long-term stability and homogeneous chemical and magnetic properties makes these particles very suitable for a wide range of applications in nanotechnology.

  12. The impact of the chemical synthesis on the magnetic properties of intermetallic PdFe nanoparticles

    International Nuclear Information System (INIS)

    Castellanos-Rubio, I.; Insausti, M.; Muro, I. Gil de; Arias-Duque, D. Carolina; Hernández-Garrido, Juan Carlos; Rojo, T.; Lezama, L.

    2015-01-01

    Palladium-rich Iron nanoparticles in the 4–8 nm range have been produced by a combination of two methods: the thermal decomposition of organometallic precursors and the reduction of metallic salts by a polyol. Herein, it is shown how the details of the synthesis have a striking impact on the magnetic and morphological properties of the final products. In the synthesis of these bimetallic nanoparticles, the use of high reaction temperatures plays an essential role in attaining good chemical homogeneity, which has proved to have a key influence on the magnetic properties. Magnetic characterization has been performed by electron magnetic resonance and magnetization measurements, which have confirmed the superparamagnetic-like behavior at room temperature. No clear traces of magnetic polarization in palladium atoms have been detected. The combination of long-term stability and homogeneous chemical and magnetic properties makes these particles very suitable for a wide range of applications in nanotechnology

  13. Synthesis, characterization and magnetic properties of room-temperature nanofluid ferromagnetic graphite

    OpenAIRE

    Souza, N. S.; Sergeenkov, S.; Speglich, C.; Rivera, V. A. G.; Cardoso, C. A.; Pardo, H.; Mombru, A. W.; Rodrigues, A. D.; de Lima, O. F.; Araujo-Moreira, F. M.

    2009-01-01

    We report the chemical synthesis route, structural characterization, and physical properties of nanofluid magnetic graphite (NFMG) obtained from the previously synthesized bulk organic magnetic graphite (MG) by stabilizing the aqueous ferrofluid suspension with an addition of active cationic surfactant. The measured magnetization-field hysteresis curves along with the temperature dependence of magnetization confirmed room-temperature ferromagnetism in both MG and NFMG samples. (C) 2009 Americ...

  14. Synthesis, structure, thermal, transport and magnetic properties of VN ceramics

    Czech Academy of Sciences Publication Activity Database

    Huber, Š.; Jankovský, O.; Sedmidubský, D.; Luxa, J.; Klimová, K.; Hejtmánek, Jiří; Sofer, Z.

    2016-01-01

    Roč. 42, č. 16 (2016), s. 18779-18784 ISSN 0272-8842 R&D Projects: GA ČR GA13-20507S Institutional support: RVO:68378271 Keywords : vanadium mononitride * phase transition * electronic structure * heat capacity * transport properties Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.986, year: 2016

  15. Synthesis and magnetic properties of superparamagnetic CoAs nanostructures

    Science.gov (United States)

    Desai, P.; Ashokaan, N.; Masud, J.; Pariti, A.; Nath, M.

    2015-03-01

    This article provides a comprehensive guide on the synthesis and characterization of superparamagnetic CoAs nanoparticles and elongated nanostructures with high blocking temperature, (TB), via hot-injection precipitation and solvothermal methods. Cobalt arsenides constitute an important family of magnetically active solids that find a variety of applications ranging from magnetic semiconductors to biomedical imaging. While the higher temperature hot-injection precipitation technique (300 °C) yields pure CoAs nanostructures, the lower temperature solvothermal method (200 °C) yields a mixture of CoAs nanoparticles along with other Co-based impurity phases. The synthesis in all these cases involved usage of triphenylarsine ((C6H5)3As) as the As precursor which reacts with solid Co2(CO)8 by ligand displacement to yield a single source precursor. The surfactant, hexadecylamine (HDA) further assists in controlling the morphology of the nanostructures. HDA also provides a basic medium and molten flux-like conditions for the redox chemistry to occur between Co and As at elevated temperatures. The influence of the length of reaction time was investigated by studying the evolution of product morphology over time. It was observed that while spontaneous nucleation at higher temperature followed by controlled growth led to the predominant formation of short nanorods, with longer reaction time, the nanorods were further converted to nanoparticles. The size of the nanoparticles obtained, was mostly in the range of 10-15 nm. The key finding of this work is exceptionally high coercivity in CoAs nanostructures for the first time. Coercivity observed was as high as 0.1 T (1000 Oe) at 2 K. These kinds of magnetic nanostructures find multiple applications in spintronics, whereas the superparamagnetic nanoparticles are viable for use in magnetic storage, ferrofluids and as contrast enhancing agents in MRI.

  16. Synthesis and magnetic properties of prussian blue modified Fe nanoparticles

    International Nuclear Information System (INIS)

    Arun, T.; Prakash, K.; Justin Joseyphus, R.

    2013-01-01

    Fe nanoparticles are prepared using a unique polyol process and modified with prussian blue (PB) at various concentrations. The presence of PB in the Fe nanoparticles are confirmed from thermal, Fourier transform infrared spectroscopy and electron microscopic analyses. The prussian blue existed on ;the surface of the nanoparticles when the concentration is 200 μM and in excess with 1000 μM. ;Fe nanoparticles are reduced in size using Pt as nucleating agent and modified with the optimum concentration of PB. The saturation magnetization decreases with the concentration of PB whereas the coercivity is influenced by the size of the Fe nanoparticles. The presence of oxide layer in Fe nanoparticles helps in the surface modification with PB. The Fe nanoparticles of particle size 53 nm modified with 200 μM of PB showed a saturation magnetization of 110 emu/g. The magnetic properties suggest that the PB modified Fe nanoparticles are better candidates for detoxification applications. - Highlights: • Fe nanoparticles surface modified with prussian blue (PB) were synthesized. • Optimum PB concentration on size reduced Fe showed better magnetic properties. • Coercivity decreased with increasing concentration of PB. • Fe-PB nanoparticles could be used for detoxification applications

  17. Synthesis, photoluminescence and magnetic properties of barium vanadate nanoflowers

    International Nuclear Information System (INIS)

    Xu, Jing; Hu, Chenguo; Xi, Yi; Peng, Chen; Wan, Buyong; He, Xiaoshan

    2011-01-01

    Graphical abstract: The flower-shaped barium vanadate was obtained for the first time. The photoluminescence and magnetic properties of the barium vanadate nanoflowers were investigated at room temperature. Research highlights: → In the paper, the flower-shaped barium vanadate were obtained for the first time. The CHM method used here is new and simple for preparation of barium vanadate. → The photoluminescence and magnetic properties of the barium vanadate nanoflowers were investigated at room temperature. The strong bluish-green emission was observed. → The ferromagnetic behavior of the barium vanadate nanoflowers was found with saturation magnetization of about 83.50 x 10 -3 emu/g, coercivity of 18.89 Oe and remnant magnetization of 4.63 x 10 -3 emu/g. → The mechanisms of PL and magnetic property of barium vanadate nanoflowers have been discussed. -- Abstract: The flower-shaped barium vanadate has been obtained by the composite hydroxide mediated (CHM) method from V 2 O 5 and BaCl 2 at 200 o C for 13 h. XRD and XPS spectrum of the as-synthesized sample indicate it is hexagonal Ba 3 V 2 O 8 with small amount of Ba 3 VO 4.8 coexistence. Scan electron microscope and transmission electron microscope display that the flower-shaped crystals are composed of nanosheets with thickness of ∼20 nm. The UV-visible spectrum shows that the barium vanadate sample has two optical gaps (3.85 eV and 3.12 eV). Photoluminescence spectrum of the barium vanadate flowers exhibits a visible light emission centered at 492 and 525 nm which might be attributed to VO 4 tetrahedron with T d symmetry in Ba 3 V 2 O 8 . The ferromagnetic behavior of the barium vanadate nanoflowers has been found with saturation magnetization of about 83.50 x 10 -3 emu/g, coercivity of 18.89 Oe and remnant magnetization of 4.63 x 10 -3 emu/g, which is mainly due to the presence of a non-orthovanadate phase with spin S = 1/2.

  18. Homogeneous Precipitation Synthesis and Magnetic Properties of Cobalt Ferrite Nanoparticles

    Directory of Open Access Journals (Sweden)

    Zhigang Liu

    2008-01-01

    Full Text Available Magnetic nanoparticles (NPs of cobalt ferrite have been synthesized via a homogeneous precipitation route using hexamethylenetetramine (HMT as the precipitant. The particle size, crystal structure, and magnetic properties of the synthesized particles were investigated by X-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer. The NPs are of cubic inverse spinel structure and nearly spherical shape. With the increase of oxidation time from 30 to 180 minutes in the reaction solution at 90∘C, the average particle size increases from ~30 nm to ~45 nm. The as-synthesized NPs ~30 nm in size show higher Ms (61.5 emu/g and moderate Hc (945 Oe and Mr/Ms (0.45 value compared with the materials synthesized by coprecipitation method using NaOH as precipitate at high pH value.

  19. Precipitation synthesis and magnetic properties of self-assembled magnetite-chitosan nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Bezdorozhev, Oleksii; Kolodiazhnyi, Taras; Vasylkiv, Oleg, E-mail: oleg.vasylkiv@nims.go.jp

    2017-04-15

    This paper reports the synthesis and magnetic properties of unique magnetite-chitosan nanostructures synthesized by the chemical precipitation of magnetite nanoparticles in the presence of chitosan. The influence of varying synthesis parameters on the morphology of the magnetic composites is determined. Depending on the synthesis parameters, magnetite-chitosan nanostructures of spherical (9–18 nm), rice-seed-like (75–290 nm) and lumpy (75–150 nm) shapes were obtained via self-assembly. Spherical nanostructures encapsulated by a 9–15 nm chitosan layer were assembled as well. The prospective morphology of the nanostructures is combined with their excellent magnetic characteristics. It was found that magnetite-chitosan nanostructures are ferromagnetic and pseudo-single domain. Rice-seed-like nanostructures exhibited a coercivity of 140 Oe and saturation magnetization of 56.7 emu/g at 300 K. However, a drop in the magnetic properties was observed for chitosan-coated spherical nanostructures due to the higher volume fraction of chitosan. - Highlights: • Magnetite-chitosan nanostructures are synthesized via self-assembly. • Different morphology can be obtained by adjusting the synthesis parameters. • An attractive combination of magnetic properties and morphology is obtained. • Magnetite-chitosan nanostructures are ferrimagnetic and pseudo-single domain.

  20. Precipitation synthesis and magnetic properties of self-assembled magnetite-chitosan nanostructures

    International Nuclear Information System (INIS)

    Bezdorozhev, Oleksii; Kolodiazhnyi, Taras; Vasylkiv, Oleg

    2017-01-01

    This paper reports the synthesis and magnetic properties of unique magnetite-chitosan nanostructures synthesized by the chemical precipitation of magnetite nanoparticles in the presence of chitosan. The influence of varying synthesis parameters on the morphology of the magnetic composites is determined. Depending on the synthesis parameters, magnetite-chitosan nanostructures of spherical (9–18 nm), rice-seed-like (75–290 nm) and lumpy (75–150 nm) shapes were obtained via self-assembly. Spherical nanostructures encapsulated by a 9–15 nm chitosan layer were assembled as well. The prospective morphology of the nanostructures is combined with their excellent magnetic characteristics. It was found that magnetite-chitosan nanostructures are ferromagnetic and pseudo-single domain. Rice-seed-like nanostructures exhibited a coercivity of 140 Oe and saturation magnetization of 56.7 emu/g at 300 K. However, a drop in the magnetic properties was observed for chitosan-coated spherical nanostructures due to the higher volume fraction of chitosan. - Highlights: • Magnetite-chitosan nanostructures are synthesized via self-assembly. • Different morphology can be obtained by adjusting the synthesis parameters. • An attractive combination of magnetic properties and morphology is obtained. • Magnetite-chitosan nanostructures are ferrimagnetic and pseudo-single domain.

  1. Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles

    Directory of Open Access Journals (Sweden)

    Sumeet Kumar

    2015-02-01

    Full Text Available In the present study, monodispersed CeO2 nanoparticles (NPs of size 8.5 ± 1.0, 11.4 ± 1.0 and 15.4 ± 1.0 nm were synthesized using the sol-gel method. Size-dependent structural, optical and magnetic properties of as-prepared samples were investigated by X-ray diffraction (XRD, field emission scanning electron microscope (FE-SEM, high resolution transmission electron microscopy (HR-TEM, ultra-violet visible (UV-VIS spectroscopy, Raman spectroscopy and vibrating sample magnetometer (VSM measurements. The value of optical band gap is calculated for each particle size. The decrease in the value of optical band gap with increase of particle size may be attributed to the quantum confinement, which causes to produce localized states created by the oxygen vacancies due to the conversion of Ce4+ into Ce3+ at higher calcination temperature. The Raman spectra showed a peak at ∼461 cm-1 for the particle size 8.5 nm, which is attributed to the 1LO phonon mode. The shift in the Raman peak could be due to lattice strain developed due to variation in particle size. Weak ferromagnetism at room temperature is observed for each particle size. The values of saturation magnetization (Ms, coercivity (Hc and retentivity (Mr are increased with increase of particle size. The increase of Ms and Mr for larger particle size may be explained by increase of density of oxygen vacancies at higher calcination temperature. The latter causes high concentrations of Ce3+ ions activate more coupling between the individual magnetic moments of the Ce ions, leading to an increase of Ms value with the particle size. Moreover, the oxygen vacancies may also produce magnetic moment by polarizing spins of f electrons of cerium (Ce ions located around oxygen vacancies, which causes ferromagnetism in pure CeO2 samples.

  2. Stacked nickelocenes: synthesis, structural characterization, and magnetic properties.

    Science.gov (United States)

    Trtica, Sabrina; Prosenc, Marc Heinrich; Schmidt, Michael; Heck, Jürgen; Albrecht, Ole; Görlitz, Detlef; Reuter, Frank; Rentschler, Eva

    2010-02-15

    The disubstitution of 1,8-diiodonaphthalene (1) with cyclopentadienyl nucleophiles reveals 1,8-(dicyclopentadienyl)-naphthalene, which rapidly undergoes Diels-Alder reaction forming 1,8-(3a',4',7',7a'-tetrahydro-4',7'-methanoindene-7a',8'-diyl)-naphthalene (2). A subsequent retro-Diels-Alder reaction in the presence of sodium hydride yields the disodium salt of 1,8-(dicyclopentadiendiyl)-naphthalene 3. The disodium salt 3 was the starting material to obtain the paramagnetic bisnickelocene derivative 4, which structure was obtained by X-ray structure analysis, revealing two nickelocenes kept together in a stacked fashion by a 1,8-naphthalene clamp. An electronic interaction between the two nickel atoms is found as a result of cyclic voltammetry, indicating five different oxidation states +4, +3, +2, +1, and 0. The magnetic properties of 4 in solution were studied by variable temperature paramagnetic (1)H NMR spectroscopy and Evans method and revealed Curie behavior between 213 and 293 K. The magnetic susceptibility of a powdered sample of 4 was measured, and an antiferromagnetic interaction with an exchange coupling of J(12) = -31.49 cm(-1) is found. In accord with experimental data, broken symmetry density functional theory (DFT) calculations revealed four antiferromagnetically coupled electrons resulting in an open shell singlet ground state.

  3. Synthesis, characterization and magnetic properties of Fe/MCM-48

    International Nuclear Information System (INIS)

    Oliva, M.I; Elias, V.R; Eimer, G.A; Silvetti, S.P; Urreta, S.E

    2008-01-01

    Mesoporous silicates called MCM-48 have a structure of interconnected pores with a cubic three dimensional arrangement, with diameters ranging from 1-10nm. This kind of pore configuration has elevated surface areas (more than 1000 m 2 /g) so these molecular MCM-48 sieves are useful for supporting and encapsulating nanophases of different transition metals, metal oxides and organometallic compounds. Nanocomposites are formed with potential applications in the areas of electronics, optics, magnetism, energy storage, drug transport and catalysis. For this work MCM-48 materials were synthesized and then modified with Fe by the wet impregnation method. Two sources of Fe were used: Fe(NO 3 ) 3 .9H 2 O and FeSO 4 .7H 2 O. The silica, previously roasted at 773 K, was suspended in a large amount of aqueous solution that initially contained the amount of iron to be deposited (5%p/p) and that was agitated for a short time. The mixture was then placed in a bath at 353K without agitation for 8 hours. Finally the water was eliminated in a rotating evaporator at 333K. The powder obtained was dried in a stove at 333K for 8 hours and calcined at 773K for 4 hours. The microstructure of the resulting composites was characterized by X-ray diffraction (XRD) and ultraviolet-visible diffuse reflectance (UVvis-DR). The magnetic properties were studied as a function of the temperature following zero field cooling (ZFC) and field cooling (FC) protocols between 300K and 5K and by measuring the hysterisis curves at different temperatures in the same range. The DRX studies confirmed a MCM-48 type structure for all the matrices, consistent with the high surface areas - around 1300 m 2 /g- measured. The structure and the surface areas of the composites were affected by the addition of the metal. While the UVvis-DR and DRX analyses of the composites obtained showed that the iron subjects in the final material are similar for both sources of iron used, they have different magnetic behaviors

  4. Synthesis, crystallographic and magnetic properties of protactinium pnictides

    International Nuclear Information System (INIS)

    Hery, Yves.

    1979-03-01

    From a theoretical point of view, protactinium lies in a very important place in the periodic system for it seems to be the first element of the actinide series where the 5f state is occupied. We have studied protactinium pnictides, particularly arsenides and antimonides. PaAs 2 , Pa 3 As 4 , PaSb 2 and Pa 3 Sb 4 were synthetized and their crystallographic properties were determined and discussed. We have measured the magnetic susceptibilities of PaC, PaAs 2 and PaSb 2 . Protactinium exhibits a dual character. In its monocarbide, which is a weakly diamagnet, it behaves as a transition element while in the temperature independent paramagnets PaAs 2 and PaSb 2 , it behaves like a 'f' element. This 'f' element character increases with increasing metal-metal distances. Furthermore the radial expansion of the protactinium 5f orbital seems to be more important than the Uranium one, and consequently the corresponding protactinium 5f electrons are less localized. In addition, some protactinium chalcogenides (βPaS 2 , γPaSe 2 and PaOSe) have been identified [fr

  5. Synthesis and Magnetic Properties of Maghemite (γ-Fe2O3 Short-Nanotubes

    Directory of Open Access Journals (Sweden)

    Xiao XH

    2010-01-01

    Full Text Available Abstract We report a rational synthesis of maghemite (γ-Fe2O3 short-nanotubes (SNTs by a convenient hydrothermal method and subsequent annealing process. The structure, shape, and magnetic properties of the SNTs were investigated. Room-temperature and low-temperature magnetic measurements show that the as-fabricated γ-Fe2O3 SNTs are ferromagnetic, and its coercivity is nonzero when the temperature above blocking temperature (TB. The hysteresis loop was operated to show that the magnetic properties of γ-Fe2O3 SNTs are strongly influenced by the morphology of the crystal. The unique magnetic behaviors were interpreted by the competition of the demagnetization energy of quasi-one-dimensional nanostructures and the magnetocrystalline anisotropy energy of particles in SNTs.

  6. Greener synthesis of magnetite nanoparticles using green tea extract and their magnetic properties

    Science.gov (United States)

    Karade, V. C.; Waifalkar, P. P.; Dongle, T. D.; Sahoo, Subasa C.; Kollu, P.; Patil, P. S.; Patil, P. B.

    2017-09-01

    The facile green synthesis method has been employed for the synthesis of biocompatible Fe3O4 magnetic nanoparticles (MNPs) using green tea extract. The effective reduction of ferric ions (Fe3+) were done using an aqueous green tea extract where it acts as reducing as well as capping agent. The effect of iron precursor to green tea extract ratio and reaction temperature was studied. The MNPs were characterized by x-ray diffraction, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, dynamic light scattering and vibrating sample magnetometer. It was observed that the reaction temperature strongly affects the magnetic and structural properties of MNPs. The magnetic measurements study showed that Fe3O4 MNPs are superparamagnetic at 300 K, while at 60 K have ferromagnetic as well as superparamagnetic contributions.

  7. 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)

  8. Single-step gas phase synthesis of stable iron aluminide nanoparticles with soft magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Vernieres, Jerome, E-mail: Jerome.vernieres@oist.jp; Benelmekki, Maria; Kim, Jeong-Hwan; Grammatikopoulos, Panagiotis; Diaz, Rosa E. [Nanoparticles by Design Unit, Okinawa Institute of Science and Technology (OIST) Graduate University, 1919-1 Tancha, Onna Son, Okinawa 904-0495 (Japan); Bobo, Jean-François [Centre d’Elaboration de Materiaux et d’Etudes Structurales (CEMES), 29 rue Jeanne Marvig, 31055 Toulouse Cedex 4 (France); Sowwan, Mukhles, E-mail: Mukhles@oist.jp [Nanoparticles by Design Unit, Okinawa Institute of Science and Technology (OIST) Graduate University, 1919-1 Tancha, Onna Son, Okinawa 904-0495 (Japan); Nanotechnology Research Laboratory, Al-Quds University, P.O. Box 51000, East Jerusalem, Palestine (Country Unknown)

    2014-11-01

    Soft magnetic alloys at the nanoscale level have long generated a vivid interest as candidate materials for technological and biomedical purposes. Consequently, controlling the structure of bimetallic nanoparticles in order to optimize their magnetic properties, such as high magnetization and low coercivity, can significantly boost their potential for related applications. However, traditional synthesis methods stumble upon the long standing challenge of developing true nanoalloys with effective control over morphology and stability against oxidation. Herein, we report on a single-step approach to the gas phase synthesis of soft magnetic bimetallic iron aluminide nanoparticles, using a versatile co-sputter inert gas condensation technique. This method allowed for precise morphological control of the particles; they consisted of an alloy iron aluminide crystalline core (DO{sub 3} phase) and an alumina shell, which reduced inter-particle interactions and also prevented further oxidation and segregation of the bimetallic core. Remarkably, the as-deposited alloy nanoparticles show interesting soft magnetic properties, in that they combine a high saturation magnetization (170 emu/g) and low coercivity (less than 20 Oe) at room temperature. Additional functionality is tenable by modifying the surface of the particles with a polymer, to ensure their good colloidal dispersion in aqueous environments.

  9. Synthesis and magnetic properties of SmOOH crystals

    Energy Technology Data Exchange (ETDEWEB)

    Samata, Hiroaki, E-mail: samata@maritime.kobe-u.ac.jp [Graduate School of Maritime Sciences, Kobe University, Fukaeminami, Higashinada, Kobe, Hyogo 658-0022 (Japan); Hanioka, Masashi [Graduate School of Maritime Sciences, Kobe University, Fukaeminami, Higashinada, Kobe, Hyogo 658-0022 (Japan); Ozawa, Tadashi C. [Materials Development Group, Superconducting Properties Unit, National Institute for Materials Science, Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2016-01-15

    Samarium oxyhydroxide (SmOOH) crystals were synthesized using a flux method. The as-grown crystals were yellowish, transparent, and elongated with a maximum length of approximately 1.0 mm. SmOOH adopts a monoclinic structure in the space group P2{sub 1}/m with a=0.4356 nm, b=0.3766 nm, c=0.6139 nm, and β=108.464°. The magnetic susceptibility of the SmOOH crystals exhibited typical Van Vleck paramagnetism, and the experimental data at temperatures above 200 K were in close agreement with the calculated results using a spin-orbit coupling constant λ=443 K (308 cm{sup −1}). - Highlights: • SmOOH crystals were synthesized via flux method and characterized. • Magnetic susceptibilities above 200 K agreed with theoretical Van Vleck values. • Discrepancies were observed at lower temperatures based on the crystalline field.

  10. Synthesis and magnetic properties of YMnO3 nanorods

    International Nuclear Information System (INIS)

    Dhinesh Kumar, R.; Jayavel, R.

    2012-01-01

    YMnO 3 nanorods have been synthesized by hydrothermal process at 200 deg C. The hexagonal phase of as-synthesized sample was confirmed by powder X-ray diffraction (XRD) analysis. High resolution scanning electron microscope (HRSEM) and Energy Dispersive X-ray (EDX) analysis have been carried out to study the surface morphology and elements presence in the sample. The magnetic behavior of the sample was studied by vibrating sample magnetometry (VSM) technique. (author)

  11. Synthesis, non-isothermal crystallization and magnetic properties of ...

    Indian Academy of Sciences (India)

    perties and modifies the physical properties of the matrix considerably. However ... perties and harmlessness to health. PEVA, in their different ..... crystals causing a depression in Tm and Tp. In all the cases, the crystallization enthalpy peak ...

  12. Uranium hetero-bimetallic complexes: synthesis, structure and magnetic properties

    International Nuclear Information System (INIS)

    Le Borgne, Th.

    2000-01-01

    The aim of this thesis is to synthesize molecular complexes with uranium and transition metal ions in close proximity, to determine the nature of the magnetic interaction between them. We decided to use Schiff bases as assembling ligands, which are unusual for uranium (IV). Although the simplest Schiff bases, such as H 2 Salen, lead to ligand exchange reactions, the bi-compartmental Schiff base H 4 L 6 (bis(3-hydroxy-salicylidene) - 2,2-dimethyl-propylene) allows the crystal structure determination of the complex [L 6 Cu(pyr)]U[L 6 Cu].2pyr, obtained by reaction of the metallo-ligand H 2 L 6 Cu with U(acac) 4 . In this manner, the complexes [L 6 Co(pyr)] 2 U and [L 6 Ni(pyr)] 2 U.pyr were also isolated, as well as the compounds in which the paramagnetic ions have been exchanged by the diamagnetic ions Zn II , Zr IV and Th IV ': [L 6 Zn(pyr)] 2 U, [L 6 Cu] 2 Zr and [L 6 Cu(pyr)]Th[L 6 Cu].2pyr. These complexes are the first which involve three metallic centres assembling by the means of a hexa-dentate Schiff base. The crystalline structures show, for all these complexes, the outstanding orthogonal arrangement of the two fragments L 6 M around the central atom which is in a dodecahedral environment of eight oxygen atoms of two Schiff bases. The syntheses of the isostructural complexes Cu2 II and Zn 2 U in which the uranium (IV) ion is close, in the first one, to the paramagnetic ion Cu II and, in the second one, to the diamagnetic ion Zn II , has allowed the use of the empiric method to determine the nature of the magnetic interaction between an f element and a transition metal. The comparison of the magnetic behaviour of two complexes Cu 2 U and Zn 2 U, expressed by the variation of χT vs T, reveals the ferromagnetic interaction in the heart of the triad Cu-U-Cu. The magnetic behaviour of the complexes Cu 2 Th et Cu 2 Zr which does not show any coupling between the two copper (II) ions and the weak antiferromagnetic interaction in the Ni 2 U compound, favour the

  13. Vanadium dioxide nanobelts: Hydrothermal synthesis and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Zakharova, G.S., E-mail: volkov@ihim.uran.ru [Institute of Solid State Chemistry, Ural Division, Russian Academy of Sciences, Pervomaiskaya ul. 91, Yekaterinburg 620041 (Russian Federation); Hellmann, I. [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung (IFW) Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Volkov, V.L. [Institute of Solid State Chemistry, Ural Division, Russian Academy of Sciences, Pervomaiskaya ul. 91, Yekaterinburg 620041 (Russian Federation); Taeschner, Ch.; Bachmatiuk, A.; Leonhardt, A.; Klingeler, R.; Buechner, B. [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung (IFW) Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany)

    2010-09-15

    VO{sub 2} (B) nanobelts were prepared by a hydrothermal method at 180 {sup o}C using V{sub 2}O{sub 5}.nH{sub 2}O sol and H{sub 2}C{sub 2}O{sub 4}.2H{sub 2}O as starting agents. The obtained nanobelts have diameters ranging from 50 to 100 nm in width, 20-30 nm in thickness with lengths up to 1.5 {mu}m. Measurements of the static magnetic susceptibility provide evidence for two phase transitions at T{sub 1} = 225 K and T{sub 2} = 290 K, respectively. Below T{sub 1}, the data suggest the presence quasi-free as well as of strongly antiferromagnetic correlated spins associated to V{sup 4+}-ions.

  14. Synthesis, characterization and magnetic properties of selected Laves and MAX phases

    International Nuclear Information System (INIS)

    Hamm, Christin Maria

    2017-01-01

    In this work the rare-earth free Laves phases Ti 2 M 3 Si with M = Mn, Fe, Co, Ni were synthesized by microwave heating and were structurally and magnetically characterized. Furthermore, the solid solution Ti 2 (Co 1-x Fe x ) 3 Si was synthesized by arc melting and spark plasma sintering, as well as their magnetic behavior was studied. In addition to the Laves phases, the focus was on the synthesis and characterization of aluminum-based MAX phases. For the first time the ternary carbides were prepared by microwave heating. The phase-pure representation of MAX phases was particularly challenging for synthetic solid-state chemistry. The susceptor-assisted microwave heating allows the synthesis of high-quality samples, which was shown in this work on M 2 AlC (M = Ti, V, Cr) and V 4 AlC 3 . Furthermore, for the first time, the doping of these materials with Mn and Fe was successful. In addition to the structural characterization of the new phases, the microstructure and magnetic properties are discussed in this work. Using these doped compounds as well as the compound V 4 AlC 3 , it has been shown that field-activated synthesis, particularly susceptor-assisted microwave heating, are a very good synthesis method for compounds which are hard or sometimes not synthesized by conventional methods.

  15. A review of the magnetic properties, synthesis methods and applications of maghemite

    Energy Technology Data Exchange (ETDEWEB)

    Shokrollahi, H., E-mail: shokrollahi@sutech.ac.ir

    2017-03-15

    It must be pointed out that maghemite (γ-Fe{sub 2}O{sub 3}) with a cubic spinel structure is a crucial material for various applications, including spin electronic devices, high-density magnetic recording, nano-medicines and biosensors. This paper has to do with a review study on the synthesis methods, magnetic properties and application of maghemite in the form of one-dimensional (1D) nanostructured materials, such as nanoparticles, nanotubes, nano-rods, and nanowires, as well as two-dimensional (2D) thin films. The results revealed that maghemite is widely used in the biomedical applications (hyperthermia, magnetic resonance imaging and drug delivery) and magnetic recording devices. The unmodified and Co/Mn modified maghemite thin films prepared by the dc-reactive magnetron sputtering show the excellent values of coercivity 2100 Oe and 3900 Oe, respectively, for the magnetic storage application. The super-paramagnetic particles with 7 nm size and the saturation magnetization of 80 emu/g prepared by the established thermolysis method are good candidates for bio-medical applications. - Highlights: • Among iron oxides, maghemite is one of the most important magnetic ceramics. • Maghemite is widely sued in magnetic recording and biomedicine. • This paper attempts to give an overview on the some important areas. • They contain synthetic methods, magnetic study, structural study and applications.

  16. Synthesis and magnetic properties of size-selected CoPt nanoparticles

    International Nuclear Information System (INIS)

    Tournus, F.; Blanc, N.; Tamion, A.; Hillenkamp, M.; Dupuis, V.

    2011-01-01

    CoPt nanoparticles are widely studied, in particular for their potentially very high magnetic anisotropy. However, their magnetic properties can differ from the bulk ones and they are expected to vary with the particle size. In this paper, we report the synthesis and characterization of well-defined CoPt nanoparticle samples produced in ultrahigh vacuum conditions following a physical route: the mass-selected low energy cluster beam deposition technique. This approach relies on an electrostatic deviation of ionized clusters which allows us to easily adjust the particle size, independently from the deposited equivalent thickness (i.e. the surface or volume particle density in a sample). Diluted samples made of CoPt particles, with different diameters, embedded in amorphous carbon are studied by transmission electron microscopy and superconducting interference device magnetometry, which gives access to the magnetic anisotropy energy distribution. We then compare the magnetic properties of two different particle sizes. The results are found to be consistent with an anisotropy constant (including its distribution) which does not evolve with the particle size in the range considered. - Highlights: → Samples of mass-selected CoPt nanoparticles are synthesized by an original physical method. → The magnetic properties of two different particle sizes are compared. → The anisotropy constant (including its dispersion) does not evolve in the range considered. → These results illustrate some invariance properties of ZFC curves.

  17. Synthesis of Ferrofluids Made of Iron Oxide Nanoflowers: Interplay between Carrier Fluid and Magnetic Properties

    Directory of Open Access Journals (Sweden)

    Federico Spizzo

    2017-11-01

    Full Text Available Ferrofluids are nanomaterials consisting of magnetic nanoparticles that are dispersed in a carrier fluid. Their physical properties, and hence their field of application are determined by intertwined compositional, structural, and magnetic characteristics, including interparticle magnetic interactions. Magnetic nanoparticles were prepared by thermal decomposition of iron(III chloride hexahydrate (FeCl3·6H2O in 2-pyrrolidone, and were then dispersed in two different fluids, water and polyethylene glycol 400 (PEG. A number of experimental techniques (especially, transmission electron microscopy, Mössbauer spectroscopy and superconducting quantum interference device (SQUID magnetometry were employed to study both the as-prepared nanoparticles and the ferrofluids. We show that, with the adopted synthesis parameters of temperature and FeCl3 relative concentration, nanoparticles are obtained that mainly consist of maghemite and present a high degree of structural disorder and strong spin canting, resulting in a low saturation magnetization (~45 emu/g. A remarkable feature is that the nanoparticles, ultimately due to the presence of 2-pyrrolidone at their surface, are arranged in nanoflower-shape structures, which are substantially stable in water and tend to disaggregate in PEG. The different arrangement of the nanoparticles in the two fluids implies a different strength of dipolar magnetic interactions, as revealed by the analysis of their magnetothermal behavior. The comparison between the magnetic heating capacities of the two ferrofluids demonstrates the possibility of tailoring the performances of the produced nanoparticles by exploiting the interplay with the carrier fluid.

  18. Synthesis, Optical, and Magnetic Properties of Graphene Quantum Dots and Iron Oxide Nanocomposites

    Directory of Open Access Journals (Sweden)

    M. Sajjad

    2018-01-01

    Full Text Available The combination of nanomaterial graphene quantum dots (GQDs with magnetic nanoparticles offers a unique set of optical and magnetic properties for future energy and medical applications. We report on the synthesis and engineering of GQDs and iron oxide (Fe3O4 nanocomposites (NCs by using a pulsed laser discharge technique. High-resolution transmission electron microscopy (HRTEM images showed a high yield of pure GQDs with 2–10 nm diameter. The hexagonal structures and lattice fringes associated with the C–C bond in GQDs were clearly identifiable. The structural and optical changes in GQDs and GQDs-Fe3O4 NC samples induced by UV light were investigated by the absorption and emission spectroscopy over the deep UV–visible spectral range. The photoluminescence spectra have shown subband π→π∗ transitions in GQDs-Fe3O4 NC. Magnetic properties of the GQDs-Fe3O4 NC samples have shown room temperature ferromagnetism induced by pure Fe3O4 nanoparticles and from the substantial spin polarized edges of GQD nanoparticles. It is concluded that the observed optical and magnetic properties could be further tailored in the studied nanocomposites for prospective medical applications.

  19. 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.

  20. Synthesis and magnetic properties of cobalt-iron/cobalt-ferrite soft/hard magnetic core/shell nanowires

    Science.gov (United States)

    Leandro Londoño-Calderón, César; Moscoso-Londoño, Oscar; Muraca, Diego; Arzuza, Luis; Carvalho, Peterson; Pirota, Kleber Roberto; Knobel, Marcelo; Pampillo, Laura Gabriela; Martínez-García, Ricardo

    2017-06-01

    A straightforward method for the synthesis of CoFe2.7/CoFe2O4 core/shell nanowires is described. The proposed method starts with a conventional pulsed electrodeposition procedure on alumina nanoporous template. The obtained CoFe2.7 nanowires are released from the template and allowed to oxidize at room conditions over several weeks. The effects of partial oxidation on the structural and magnetic properties were studied by x-ray spectrometry, magnetometry, and scanning and transmission electron microscopy. The results indicate that the final nanowires are composed of 5 nm iron-cobalt alloy nanoparticles. Releasing the nanowires at room conditions promoted surface oxidation of the nanoparticles and created a CoFe2O4 shell spinel-like structure. The shell avoids internal oxidation and promotes the formation of bi-magnetic soft/hard magnetic core/shell nanowires. The magnetic properties of both the initial single-phase CoFe2.7 nanowires and the final core/shell nanowires, reveal that the changes in the properties from the array are due to the oxidation more than effects associated with released processes (disorder and agglomeration).

  1. Effects of synthesis variables on the magnetic properties of CoFe{sub 2}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Briceno, Sarah, E-mail: sarahbriara@gmail.com [Laboratorio de Fisica de la Materia Condensada, Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas (IVIC), Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); Braemer-Escamilla, Werner; Silva, Pedro [Laboratorio de Fisica de la Materia Condensada, Centro de Fisica, Instituto Venezolano de Investigaciones Cientificas (IVIC), Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); Delgado, Gerzon E. [Laboratorio de Cristalografia, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101-A (Venezuela, Bolivarian Republic of); Plaza, Eric [Laboratorio de Microscopia Electronica. Instituto Zuliano de Investigaciones Tecnologicas. Apartado 331. Km. 15. La Canada (Venezuela, Bolivarian Republic of); Palacios, Jordana [Laboratorio de Polimeros, Centro de Quimica, Instituto Venezolano de Investigaciones Cientificas (IVIC), Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); Canizales, Edgard [Area de Analisis Quimico Inorganico. PDVSA. INTEVEP. Los Teques 1070-A (Venezuela, Bolivarian Republic of)

    2012-09-15

    Cobalt ferrite nanoparticles (CoFe{sub 2}O{sub 4}) have been synthesized using precipitation in water solution with polyethylene glycol as surfactant. Influence of various synthesis variables included pH, reaction time and annealing temperature on the magnetic properties and particle sizes has also been studied. Structural identification of the samples was carried out using Thermogravimetric and Differential thermal analysis, X-ray diffraction, Fourier transform infrared spectroscopy, Scanning electron microscopy, High resolution transmission electron microscopy. Vibrating sample magnetometer was used for the magnetic investigation of the samples. Magnetic properties of nanoparticles show strong dependence on the particle size. The magnetic properties increase with pH of the precipitating medium and annealing temperature while the coercivity goes through a maximum, peaking at around 25 nm. - Highlights: Black-Right-Pointing-Pointer CoFe{sub 2}O{sub 4} have been synthesized via chemical synthesis route using PEG as surfactant. Black-Right-Pointing-Pointer Influence of various synthesis variables on the magnetic properties has been studied. Black-Right-Pointing-Pointer Magnetic properties of nanoparticles show strong dependence on the particle size. Black-Right-Pointing-Pointer Magnetic properties increase with pH and annealing temperature.

  2. Microemulsion synthesis and magnetic properties of FexNi(1-x) alloy nanoparticles

    Science.gov (United States)

    Beygi, H.; Babakhani, A.

    2017-01-01

    This paper investigates synthesis of FexNi(1-x) bimetallic nanoparticles by microemulsion method. Through studying the mechanism of nanoparticles formation, it is indicated that synthesis of nanoparticles took placed by simultaneous reduction of metal ions and so nanoparticles structure is homogeneous alloy. FexNi(1-x) nanoparticles with different sizes, morphologies and compositions were synthesized by changing the microemulsion parameters such as water/surfactant/oil ratio, presence of co-surfactant and NiCl2·6H2O to FeCl2·4H2O molar ratio. Synthesized nanoparticles were characterized by transmission electron microscopy, particle size analysis, X-ray diffraction, atomic absorption and thermogravimetric analyses. The results indicated that, presence of butanol as co-surfactant led to chain-like arrangement of nanoparticles. Also, finer nanoparticles were synthesized by decreasing the amount of oil and water and increasing the amount of CTAB. The results of vibrating sample magnetometer suggested that magnetic properties of FexNi(1-x) alloy nanoparticles were affected by composition, size and morphology of the particles. Spherical and chain-like FexNi(1-x) alloy nanoparticles were superparamagnetic and ferromagnetic, respectively. Furthermore, higher iron in the composition of nanoparticles increases the magnetic properties.

  3. Effect of Synthesis Parameters on the Structure and Magnetic Properties of Magnetic Manganese Ferrite/Silver Composite Nanoparticles Synthesized by Wet Chemistry Method

    DEFF Research Database (Denmark)

    Huy, L.T.; Tam, L.T.; Phan, V.N.

    2016-01-01

    In the present work, magnetic manganese ferrite/silver (MnFe2O4-Ag) composite nanoparticles were synthesized by wet chemistry method. This synthesis process consists of two steps: first, the seed of manganese ferrite nanoparticles (MnFe2O4 NPs) was prepared by a coprecipitationmethod; second......, growth of silver nanoparticles (AgNPs) on the MnFe2O4 seed by modified photochemical reaction. We have conducted systematically the effects of synthesis parameters such as pH value, synthesis time, precursor salts concentration, mass ratio and stabilizing agents on the structure and magnetic properties......-prepared MnFe2O4-Ag magnetic nanocomposites display excellent properties of high crystallinity, long-term aggregation stability in aqueous medium, large saturation magnetization in the range of 15-20 emu/g, and small sizes of Ag-NPs similar to 20 nm. These exhibited properties made the MnFe2O4-Ag...

  4. Carbon nanotubes/magnetite hybrids prepared by a facile synthesis process and their magnetic properties

    International Nuclear Information System (INIS)

    Zhang Li; Ni, Qing-Qing; Natsuki, Toshiaki; Fu Yaqin

    2009-01-01

    In this paper, a facile synthesis process is proposed to prepare multiwalled carbon nanotubes/magnetite (MWCNTs/Fe 3 O 4 ) hybrids. The process involves two steps: (1) water-soluble CNTs are synthesized by one-pot modification using potassium persulfate (KPS) as oxidant. (2) Fe 3 O 4 is assembled along the treated CNTs by employing a facile hydrothermal process with the presence of hydrazine hydrate as the mineralizer. The treated CNTs can be easily dispersed in aqueous solvent. Moreover, X-ray photoelectron spectroscopy (XPS) analysis reveals that several functional groups such as potassium carboxylate (-COOK), carbonyl (-C=O) and hydroxyl (-C-OH) groups are formed on the nanotube surfaces. The MWCNTs/Fe 3 O 4 hybrids are characterized with respect to crystal structure, morphology, element composition and magnetic property by X-ray diffraction (XRD), transmission electron microscopy (TEM), XPS and superconducting quantum interference device (SQUID) magnetometer. XRD and TEM results show that the Fe 3 O 4 nanoparticles with diameter in the range of 20-60 nm were firmly assembled on the nanotube surface. The magnetic property investigation indicated that the CNTs/Fe 3 O 4 hybrids exhibit a ferromagnetic behavior and possess a saturation magnetization of 32.2 emu/g. Further investigation indicates that the size of assembled Fe 3 O 4 nanoparticles can be turned by varying experiment factors. Moreover, a probable growth mechanism for the preparation of CNTs/Fe 3 O 4 hybrids was discussed.

  5. Microwave Synthesis and Magnetic Properties of High Tc Superconductor MGB2

    International Nuclear Information System (INIS)

    Koeseoglu, Y.

    2004-01-01

    Polycrystalline powders of MgB 2 have been synthesized by microwave synthesis technique. Crystallographic information of the sample was investigated by powder X-ray diffraction (XRD). The main phase was determined as MgB2, and secondary phases as MgB4 and MgO. The temperature dependence of magnetic properties of polycrystalline MgB2, synthesized by using microwave heating of the constituents have been characterized by SQUID magnetometer and X-band EPR spectrometer. The transition temperature to the superconducting phase is observed as 39K for both measurements. An isotropic, strong and very narrow EPR signal corresponding to free electron g-value (ge=2.0023) is observed. The observed line broadening with decreasing temperature might arise from the dipolar interactions between the superparamagnetic nanoparticles. Normally, the internal magnetic field originating from magnetic entities is expected to be more uniform as a result of highly ordered magnetic moments at low temperatures; giving narrower ESR line in contrary in our case. While the ESR line is broadened, the signal intensity is drastically decreased just below T c =39 K corresponding to a transition temperature from normal to superconducting state. Some minor changes in both intensity and line width curves might be taken as signs for changes of local crystalline field symmetry around weakly localized conduction electrons or holes, which are the sources of ESR signal in MgB 2 compound

  6. Synthesis and magnetic property of T4 virus-supported gold-coated iron ternary nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Xu Ziming; Sun Hongjing; Gao Faming, E-mail: fmgao@ysu.edu.cn; Hou Li; Li Na [Yanshan University, Key Laboratory of Applied Chemistry (China)

    2012-12-15

    Herein, we present a novel method based on the use of the symmetrical T4 bacteriophage capsid as a scaffold for preparing the gold-coated iron ternary core/shell nanostructure. Results showed that the thick gold shell was obtained to effectively protect Fe core from oxidation. Magnetic measurements showed that the nanocomposites were superparamagnetic at room temperature with a blocking temperature of about 35 K. At 3 K, its coercivity of 1142.86 Oe was larger than the existing experimental values. The magnetic property of Au/T4 was also tested, demonstrating the source of the magnetic sample arising from the Fe core only. The absorption spectrum of the Fe-Au/T4 complex was measured and compared with gold/virus. Different thickness gold shells were controlled in the synthesis by tuning the Au salt addition. On the basis of results and discussion, we further speculated the general growing mechanism of the template-supported Fe-Au process.

  7. Synthesis and magnetic property of T4 virus-supported gold-coated iron ternary nanocomposite

    Science.gov (United States)

    Xu, Ziming; Sun, Hongjing; Gao, Faming; Hou, Li; Li, Na

    2012-12-01

    Herein, we present a novel method based on the use of the symmetrical T4 bacteriophage capsid as a scaffold for preparing the gold-coated iron ternary core/shell nanostructure. Results showed that the thick gold shell was obtained to effectively protect Fe core from oxidation. Magnetic measurements showed that the nanocomposites were superparamagnetic at room temperature with a blocking temperature of about 35 K. At 3 K, its coercivity of 1142.86 Oe was larger than the existing experimental values. The magnetic property of Au/T4 was also tested, demonstrating the source of the magnetic sample arising from the Fe core only. The absorption spectrum of the Fe@Au/T4 complex was measured and compared with gold/virus. Different thickness gold shells were controlled in the synthesis by tuning the Au salt addition. On the basis of results and discussion, we further speculated the general growing mechanism of the template-supported Fe@Au process.

  8. Enhancement of structural and magnetic properties of M-type hexaferrite permanent magnet based on synthesis temperature

    Science.gov (United States)

    Anjum, Safia; Sehar, Fatima; Mustafa, Zeeshan; Awan, M. S.

    2018-01-01

    The main purpose of this research work is to develop the single domain magnetic particles of M-type barium hexaferrite (BaFe12O19) using oxide precursors employing conventional powder metallurgy technique. The phase formation and magnetic performance of the powders and magnets will be optimized by adjusting calcination and sintering temperatures. The synthesis of M-type barium hexaferrite was carried out in two sections. A series of four samples have been prepared by initial wet mixed powders calcined at different temperatures, i.e., 750, 850, 950 and 1050 °C. On the basis of structural analysis, the sample calcined at 950 °C has been selected and further divided into four parts to sintered them at 1100, 1150, 1200 and 1250 °C. The structural measurements depict the confirmation of M-type barium hexaferrite structure. SEM micrographs show the hexagonal-shaped grains. The abrupt decrease in coercivity for the sample sintered at 1250 °C has been seen which may be due to high sintering temperature, at which the particles have multi-domain properties.

  9. Synthesis, properties, and application in peptide chemistry of a magnetically separable and reusable biocatalyst

    Science.gov (United States)

    Liria, Cleber W.; Ungaro, Vitor A.; Fernandes, Raphaella M.; Costa, Natália J. S.; Marana, Sandro R.; Rossi, Liane M.; Machini, M. Teresa

    2014-11-01

    Enzyme-catalyzed chemical processes are selective, very productive, and generate little waste. Nevertheless, they may be optimized using enzymes bound to solid supports, which are particularly important for protease-mediated reactions since proteases undergo fast autolysis in solution. Magnetic nanoparticles are suitable supports for this purpose owing to their high specific surface area and to be easily separated from reaction media. Here we describe the immobilization of bovine α-chymotrypsin (αCT) on silica-coated superparamagnetic nanoparticles (Fe3O4@silica) and the characterization of the enzyme-nanoparticle hybrid (Fe3O4@silica-αCT) in terms of protein content, properties, recovery from reaction media, application, and reuse in enzyme-catalyzed peptide synthesis. The results revealed that (i) full acid hydrolysis of the immobilized protease followed by amino acid analysis of the hydrolyzate is a reliable method to determine immobilization yield; (ii) despite showing lower amidase activity and a lower K cat/ K m value for a specific substrate than free αCT, the immobilized enzyme is chemically and thermally more stable, magnetically recoverable from reaction media, and can be consecutively reused for ten cycles to catalyze the amide bond hydrolysis and ester hydrolysis of the protected dipeptide Z-Ala-Phe-OMe. Altogether, these properties indicate the potential of Fe3O4@silica-αCT to act as an efficient, suitably stable, and reusable catalyst in amino acid, peptide, and protein chemistry as well as in proteomic studies.

  10. Enhancing the magnetic properties of magnetic nanoparticles

    DEFF Research Database (Denmark)

    Ahlburg, Jakob; Saura-Múzquiz, Matilde; Stingaciu, Marian

    with a similar magnetic performance. There are several different ways of enhancing magnetic properties of 3d magnetic compounds. This includes, size control, core-shell particles or mixing hard and soft magnetic materials together to achieve an exchange coupling between the compounds and enhancing the magnetic...... energy product. In order to control the particle size, a hydrothermal synthesis is preferred. This followed by reduction or the oxides into either core shell particles, or a mixture of magnetic oxides and a metallic phase....

  11. Synthesis and study of the magnetic properties of thallium-based over-doped superconducting compounds

    International Nuclear Information System (INIS)

    Opagiste, C.

    1994-07-01

    The synthesis, structure and magnetic properties of the normal and superconducting states of over-doped Tl 2 Ba 2 Cu O 6±x and Tl 2 Ba 2 Ca Cu 2 O 8±x superconducting compounds, are presented. Synthesis under high pressure using Tl 2 Ba 2 O 5 as a precursor avoids thallium losses and Ba Cu O 2 formation. The entire over-doped region has been investigated (Tc ranging from 0 to 92 K) and the different stability zones for the two crystallographic structures have been explored. The orthorhombic structure is shown to be stoichiometric in cations, while the tetragonal one could present thallium deficiency. Clear correlations have been established between Tc and the lattice parameters for the two phases. It has been observed that the Meissner fraction increased with Tc and that the reversibility domain was more extended for samples having a Tc near the maximal value, which must be linked to the decrease of the anisotropy with over-doping. In the reversible regime, the mixed state is affected by thermal fluctuations around Tc. Evolution of the penetration depth with Tc is examined; it shows that the optimum doped compound (maximal Tc) behaves as a BCS type superconductor. The over-doping results in a penetration depth behaviour which strongly deviates from the standard model (BCS, two fluids). The zero temperature, obtained by extrapolation, seems to be independent of the over-doping. 54 figs., 3 tabs., 168 refs

  12. Thorium/uranium mixed oxide nano-crystals: Synthesis, structural characterization and magnetic properties

    International Nuclear Information System (INIS)

    Hudry, Damien; Griveau, Jean-Christophe; Apostolidis, Christos; Colineau, Eric; Rasmussen, Gert; Walter, Olaf; Wang, Di; Venkata Sai Kiran Chakravadhaluna; Courtois, Eglantine; Kubel, Christian

    2014-01-01

    One of the primary aims of the actinide community within nano-science is to develop a good understanding similar to what is currently the case for stable elements. As a consequence, efficient, reliable and versatile synthesis techniques dedicated to the formation of new actinide-based nano-objects (e.g., nano-crystals) are necessary. Hence, a 'library' dedicated to the preparation of various actinide based nano-scale building blocks is currently being developed. Nano-scale building blocks with tunable sizes, shapes and compositions are of prime importance. So far, the non-aqueous synthesis method in highly coordinating organic media is the only approach which has demonstrated the capability to provide size and shape control of actinide-based nano-crystals (both for thorium and uranium, and recently extended to neptunium and plutonium). In this paper, we demonstrate that the non-aqueous approach is also well adapted to control the chemical composition of the nano-crystals obtained when mixing two different actinides. Indeed, the controlled hot co-injection of thorium acetylacetonate and uranyl acetate (together with additional capping agents) into benzyl ether can be used to synthesize thorium/uranium mixed oxide nano-crystals covering the full compositional spectrum. Additionally, we found that both size and shape are modified as a function of the thorium/uranium ratio. Finally, the magnetic properties of the different thorium/uranium mixed oxide nano-crystals were investigated. Contrary to several reports, we did not observe any ferromagnetic behavior. As a consequence, ferromagnetism cannot be described as a universal feature of nano-crystals of non-magnetic oxides as recently claimed in the literature. (authors)

  13. 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.

  14. Synthesis of magnetic graphene oxide–TiO2 and their antibacterial properties under solar irradiation

    International Nuclear Information System (INIS)

    Chang, Ying-Na; Ou, Xiao-Ming; Zeng, Guang-Ming; Gong, Ji-Lai; Deng, Can-Hui; Jiang, Yan; Liang, Jie; Yuan, Gang-Qiang; Liu, Hong-Yu; He, Xun

    2015-01-01

    Highlights: • Magnetic graphene oxide–TiO 2 (MGO–TiO 2 ) composites were synthesized. • MGO–TiO 2 had excellent antibacterial activity toward Escherichia coli. • MGO–TiO 2 could effectively and rapidly separate from aqueous solution. • Carbonates and phosphates significantly reduced the bacterial survival rate. - Abstract: Titanium dioxide (TiO 2 ) has been intensively researched and increasingly used as antibacterial agent, but it suffers from separation inconvenience. Its effective removal from water after reaction while maintaining its high antibacterial activity becomes necessary. In this work, it was the first time the magnetic graphene oxide–TiO 2 (MGO–TiO 2 ) composites were prepared through a simple synthesis method. The results indicated that MGO–TiO 2 exhibited a good antibacterial activity against Escherichia coli. MGO–TiO 2 was found to almost completely inactivate the E. coli within 30 min under solar irradiation. The effect of inorganic ions present in E. coli suspension was also evaluated. Compared with other ions, HCO 3 − and HPO 4 2− had a greater influence on the antibacterial property

  15. Facile and rapid synthesis of nickel nanowires and their magnetic properties

    International Nuclear Information System (INIS)

    Tang Shaochun; Zheng Zhou; Vongehr, Sascha; Meng Xiangkang

    2011-01-01

    The present work reports a facile and rapid microwave-assisted route to synthesize nickel nanowires with a necklace-like morphology and lengths up to several hundreds of microns. The wires consist of many crystallites with an average size of 25 ± 2 nm. The synthesis does not use templates or magnetic fields and needs only 6 min, which is more than 480 times faster than that needed for Ni wires prepared at 180 °C using conventional heating. Nickel nanostructures with various morphologies including spheres, chains and irregular particles with porous surfaces can also be obtained by adjusting reaction parameters. Polyvinylpyrrolidone (PVP) is found to be vital for the formation of the one-dimensional chains and a high concentration of PVP smoothes their surfaces to result in the appearance of wires. This rapid one-pot procedure combines the formation of nanoparticles, their oriented assembly into chains, and the subsequent shaping of wires. The Ni nanostructures show variable magnetic properties. The prepared nickel wires have a high mechanical stability and exhibit much higher coercivity than bulk nickel, Ni nanoparticles and their aggregations, which promise potential applications in micromechanical sensors, memory devices and other fields.

  16. Synthesis, crystal structure and magnetic properties of U2RuGa8

    International Nuclear Information System (INIS)

    Grin', Yu.N.; Rogl', P.; Aksel'rud, L.G.; Pecharskij, V.K.; Yarmolyuk, Ya.P.

    1988-01-01

    Synthesis of a new uranium intermetallic compound of U 2 RuGa 8 composition was conducted. The compound crystallizes in Ho 2 CoGa 8 structural type, met earlier only in compounds of rare earths. Magnetic susceptibility of the compound is rather high and is practically independent of temperature in 80-300 K range. This feature is typical for paramagnetism of electron gas and testifies to the absence of localized magnetic moments on ruthenium and uranium atoms

  17. Influence of synthesis method on structural and magnetic properties of cobalt ferrite nanoparticles

    International Nuclear Information System (INIS)

    Gyergyek, Saso; Makovec, Darko; Kodre, Alojz; Arcon, Iztok; Jagodic, Marko; Drofenik, Miha

    2010-01-01

    properties are strongly affected by the synthesis method used.

  18. Radiolytic Synthesis of Magnetic Nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Grdanovska, Slavica; Tissot, Chanel; Barkatt, Aaron; Al-Sheikhly, Mohamad [Nuclear Engineering Program – Department of Materials Science and Engineering, University of Maryland, College Park, MD (United States)

    2011-07-01

    Magnetic nanocomposites, in which magnetic nanoparticles are encapsulated in polymeric matrices, have important applications in medicine, electronics and mechanical devices. However, the development of processes leading to magnetic nanocomposites with desirable, predictable and reproducible properties has turned out to be a difficult challenge. To date, most studies have concentrated on a magnetic oxide, primarily magnetite (Fe{sub 3}O{sub 4}), as the encapsulated phase. However, the synthesis of batches of magnetite with homogeneous properties at reasonably low temperature is a delicate operation. Indeed, commercial lots of magnetite powder, despite having bulk Fe{sub 3}O{sub 4} stoichiometry, turn out to have large variations in structure and in magnetic properties. The difficulties in controlling the product are greatly magnified when the particle size is in the nanometer range.

  19. Synthesis, magnetic and transport properties of oxygen-free CrN ceramics

    Czech Academy of Sciences Publication Activity Database

    Jankovský, O.; Sedmidubský, D.; Huber, Štěpán; Šimek, P.; Šofer, Z.

    2014-01-01

    Roč. 34, č. 16 (2014), s. 4131-4136 ISSN 0955-2219 R&D Projects: GA ČR GA13-20507S Institutional support: RVO:68378271 Keywords : chromium nitride * nitride ceramics * magnetotransport properties * thermoelectric properties Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.947, year: 2014

  20. A novel rhombohedron-like nickel ferrite nanostructure: Microwave combustion synthesis, structural characterization and magnetic properties

    Directory of Open Access Journals (Sweden)

    G. Suresh Kumar

    2016-09-01

    Full Text Available Research on nickel ferrite nanostructures has drawn a great interest because of its inherent chemical, physical and electronic properties. In this study, we have synthesized rhombohedron – like nickel ferrite nanostructure by a rapid microwave assisted combustion method using ethylenediamminetetraacetic acid as a chelating agent. X-ray diffraction, Fourier transform infrared spectrometer, transmission electron microscope and energy dispersive X-ray microanalyser were used to characterize the prepared sample. The magnetic behaviour was analysed by means of field dependent magnetization measurement which indicates that the prepared sample exhibits a soft ferromagnetic nature with saturation magnetization of 63.034 emu/g. This technique can be a potential method to synthesize novel nickel ferrite nanostructure with improved magnetic properties.

  1. Synthesis and magnetic properties of single-crystalline BaFe12O19 nanoparticles

    International Nuclear Information System (INIS)

    Yu Jiangying; Tang Shaolong; Zhai Lin; Shi Yangguang; Du Youwei

    2009-01-01

    Rod-like and platelet-like nanoparticles of simple-crystalline barium hexaferrite (BaFe 12 O 19 ) have been synthesized by the molten salt method. Both particle size and morphology change with the reaction temperature and time. The easy magnetization direction (0 0 l) of the BaFe 12 O 19 nanoparticles has been observed directly by performing X-ray diffraction on powders aligned at 0.5 T magnetic field. The magnetic properties of the BaFe 12 O 19 magnet were investigated with various sintering temperatures. The maximum values of saturation magnetization (σ s =65.8 emu/g), remanent magnetization (σ r =56 emu/g) and coercivity field (H ic =5251 Oe) of the aligned samples occurred at the sintering temperatures of 1100 deg. C. These results indicate that BaFe 12 O 19 nanoparticles synthesized by the molten salt method should enable detailed investigation of the size-dependent evolution of magnetism, microwave absorption, and realization of a nanodevice of magnetic media.

  2. Metal–organic coordination architectures of tetrazole heterocycle ligands bearing acetate groups: Synthesis, characterization and magnetic properties

    International Nuclear Information System (INIS)

    Hu, Bo-Wen; Zheng, Xiang-Yu; Ding, Cheng

    2015-01-01

    Two new coordination complexes with tetrazole heterocycle ligands bearing acetate groups, [Co(L) 2 ] n (1) and [Co 3 (L) 4 (N 3 ) 2 ·2MeOH] n (2) (L=tetrazole-1-acetate) have been synthesized and structurally characterized. Single crystal structure analysis shows that the cobalt-complex 1 has the 3D 3,6-connected (4 2 .6) 2 (4 4 .6 2 .8 8 .10)-ant topology. By introducing azide in this system, complex 2 forms the 2D network containing the [Co 3 ] units. And the magnetic properties of 1 and 2 have been studied. - Graphical abstract: The synthesis, crystal structure, and magnetic properties of the new coordination complexes with tetrazole heterocycle ligands bearing acetate groups are reported. - Highlights: • Two novel Cobalt(II) complexes with tetrazole acetate ligands were synthesized. • The magnetic properties of two complexes were studied. • Azide as co-ligand resulted in different structures and magnetic properties. • The new coordination mode of tetrazole acetate ligand was obtained.

  3. Synthesis and magnetic properties of inverted core-shell polyaniline-ferrite composite

    Energy Technology Data Exchange (ETDEWEB)

    Donescu, Dan [National Institute for Research & Development in Chemistry and Petrochemistry - ICECHIM, 202 Spl. Independentei, 060021, Bucharest (Romania); Fierascu, Radu Claudiu, E-mail: radu_claudiu_fierascu@yahoo.com [National Institute for Research & Development in Chemistry and Petrochemistry - ICECHIM, 202 Spl. Independentei, 060021, Bucharest (Romania); Ghiurea, Marius [National Institute for Research & Development in Chemistry and Petrochemistry - ICECHIM, 202 Spl. Independentei, 060021, Bucharest (Romania); Manaila-Maximean, Doina [University Politehnica of Bucharest, Department of Physics, 313 Spl. Independentei, 060042, Bucharest (Romania); Nicolae, Cristian Andi; Somoghi, Raluca; Spataru, Catalin Ilie [National Institute for Research & Development in Chemistry and Petrochemistry - ICECHIM, 202 Spl. Independentei, 060021, Bucharest (Romania); Stanica, Nicolae [Institute of Physical Chemistry “Ilie Murgulescu”, 202 Spl. Independentei, 060021, Bucharest (Romania); Raditoiu, Valentin [National Institute for Research & Development in Chemistry and Petrochemistry - ICECHIM, 202 Spl. Independentei, 060021, Bucharest (Romania); Vasile, Eugeniu [SC METAV – CD SA, 31 C. A. Rosetti Str., 021051, Bucharest (Romania)

    2017-08-31

    The present paper studies the effect of polyaniline grafting on magnetite functionalized with aminopropyltrimethoxysilane. All the compounds were characterized by analytical techniques (X-ray fluorescence, X-ray diffraction, Fourier transform infrared spectroscopy, thermal analysis, Transmission electron microscopy), as well as by determining their magnetic properties. The electron microscopy analysis of the hybrids shows similar morphologies for all the samples. The presence of the iron atoms on the surface of the final product supports the idea of the existence of an inverted core-shell type structure, the more polar ferrite orienting itself towards water. The correlation between the maximum grafting probability and the maximum magnetization is evidenced, demonstrating the importance of the polymer grafting method on the magnetic properties.

  4. Template-free synthesis of sub-micrometric cobalt fibers with controlled shape and structure. Characterization and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Lakhdar, Allagui [Laboratoire de Physique des Matériaux Lamellaires et Nano-Matériaux Hybrides, Faculté des Sciences de Bizerte, Université de Carthage, 7021 Bizerte (Tunisia); Borges, Joao P. [i3N/CENIMAT, Department of Materials Science, Faculty of Science and Technology, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516 Caparica (Portugal); Ben Haj Amara, Abdesslam [Laboratoire de Physique des Matériaux Lamellaires et Nano-Matériaux Hybrides, Faculté des Sciences de Bizerte, Université de Carthage, 7021 Bizerte (Tunisia); Dakhlaoui-Omrani, Amel, E-mail: dakhlaoui_amel@yahoo.fr [Department of Chemistry, Faculty of Sciences and Arts-Khulais, University of Jeddah, Khulais, P. O. Box 355, Postal Code 21921 (Saudi Arabia); Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National des Recherches en Sciences des Matériaux, Technopôle de Bordj Cedria, BP 73, 8027 Soliman (Tunisia)

    2017-03-01

    Sub-micrometric Co fibers were prepared via a modified polyol process at 90 °C under an external magnetic field of about 550 Oe, using ethelyne glycol as solvent and hydrazine as reducing agent. The structure, the size and the morphology of the as-elaborated products were highly controlled through properly monitoring the synthesis parameters (amount of NaOH added, the amount of the reducing agent, precursor’ concentration and precursors mixing protocol). The XRD characterization confirmed the formation of pure cobalt powders with either hexagonal compact (hcp) or face-centered-cubic (fcc) structure depending on the concentration of the metal precursor and sodium hydroxide. The scanning electron microscopy observations of the powders shows sub-micrometric fibers with about 0.4–0.6 µm in diameter and a length that could reach 15 µm. Fibers prepared at high reducing ratio were constituted of flower-like spheres that coalesce in the direction of the applied magnetic field. For their high contact surface, these fibers offer new opportunities for catalysis applications. The hysteresis loop measurements show an enhancement of the Hc of the as-obtained fibers compared to their bulk counterparts and permit to confirm the relationship between the structure and the magnetic properties of the materials. - Highlights: • Template free synthesis of cobalt sub-micrometric fibers. • High control of the structure the structure, the size and the morphology of the products through properly monitoring the synthesis parameters. • cobalt sub-micrometric fibers with enhanced magnetic properties compared to bulk cobalt.

  5. Synthesis, structure and magnetic properties of crystallographically aligned CuCr_2Se_4 thin films

    International Nuclear Information System (INIS)

    Esters, Marco; Liebig, Andreas; Ditto, Jeffrey J.; Falmbigl, Matthias; Albrecht, Manfred; Johnson, David C.

    2016-01-01

    We report the low temperature synthesis of highly textured CuCr_2Se_4 thin films using the modulated elemental reactant (MER) method. The structure of CuCr_2Se_4 is determined for the first time in its thin film form and exhibits cell parameters that are smaller than found in bulk CuCr_2Se_4. X-ray diffraction and precession electron diffraction show a strong degree of crystallographic alignment of the crystallites, where the axis is oriented perpendicular to the substrate surface, while being rotationally disordered within the plane. Temperature and field dependent in-plane and out-of-plane magnetization measurements show that the film is ferromagnetic with a Curie temperature of 406 K CuCr_2Se_4 synthesized utilizing the MER method shows stronger magnetic anisotropy (effective anisotropy: 1.82 × 10"6 erg cm"−"3; shape anisotropy: 1.07 × 10"6 erg cm"−"3), with the easy axis lying out of plane, and a larger magnetic moment (6 μ_B/f.u.) than bulk CuCr_2Se_4. - Highlights: • Crystallographically aligned, phase pure CuCr_2Se_4 were synthesized. • The degree of alignment decreases with annealing time. • The films are ferromagnetic with the easy axis along the direction. • The magnetization is larger than bulk CuCr_2Se_4 or other CuCr_2Se_4 films made to date.

  6. The influence of surfactant on the synthesis of gamma ferric oxide: implications on phase composition and magnetic properties

    International Nuclear Information System (INIS)

    Narasimhan, B.R.V.; Prabhakar, S.; Manohar, P.; Gnanam, F.D.

    2002-01-01

    It has already been established that ferrous carbonate precipitated from the reaction of ferrous sulphate and sodium carbonate, on direct thermal decomposition yields gamma ferric oxide. The present work describes the effect of sodium lauryl sulphate (Sodium dodecyl sulphate) on the synthesis of gamma ferric oxide when it is introduced during the precipitation of ferrous carbonate. Since ferrous carbonate undergoes rapid oxidation on standing in air, the extent of oxidation in presence of sodium lauryl sulphate is also studied using oxidation-reduction potential measurements. The ferric oxide powders are characterized for phase analysis (XRD), magnetic properties (VSM) and particle size analysis. (author)

  7. Synthesis and magnetic properties of carbon-coated FeRu, CoRu, and NiRu nanoalloys

    Energy Technology Data Exchange (ETDEWEB)

    El-Gendy, A.A.; Khavrus, V.O.; Hampel, S.; Leonhardt, A.; Klingeler, R.; Buechner, B. [Leibniz Institute for Solid State and Materials Research (IFW) Dresden (Germany)

    2010-07-01

    Carbon coated FeRu, CoRu and NiRu nanoalloys have been synthesised by high pressure chemical vapour deposition (HPCVD). The formation of the core-shell nanoalloys with a mean diameter around 8 nm has been confirmed by means of high resolution transmission electron microscopy imaging (HRTEM), energy dispersive X-ray (EDX) analysis, and X-ray diffraction (XRD). We show the effect of the synthesis parameters on the actual composition of the nanoalloys and on their magnetic properties and we discuss their feasibility for applications in medical hyperthermia.

  8. Physical and magnetic properties, microstructure of bonded magnet NdFeB prepared by using synthesis rubber

    International Nuclear Information System (INIS)

    Suprapedi; Sardjono, P.; Muljadi

    2016-01-01

    The magnet permanent has been made by using NdFeB (NQP-B) powder with purity 99.90% and polymer rubber with purity 90%. This research was done to determine the effect of the polymer (rubber) composition as binder in the manufacture of bonded magnet NdFeB on physical properties, microstructure and magnetic properties. Bonded magnets are magnet material made from a mixture of magnetic powder as a filler and the polymer as a matrix material or as binder to bind the magnetic particles. The NdFeB (NQP-B) powder fractions of bonded magnets NdFeB investigated were as follows: a) 97 wt.% of NdFeB (NQP-B) and 3 wt.% of rubber,b) 95wt.% of NdFeB (NQP-B) and 5 wt.% of rubber, c) 93 wt.% of NdFeB (NQP-B) and 7 wt.% of rubber, d) 91 wt.% of NdFeB (NQP-B) and 9 wt.% of rubber. Both raw materials were mixed by using mixer until homogen with total weight about 16 g for each sample, then added 0.3 ml of catalyst and mixed again and put in dies mould and compacted at pressure 30 MPa, then dried for 2 hours at room temperature. The dried samples was characterized such as: bulk density measurement and magnetic properties by using BH-curve permeagraph. The bulk density values of the sample bonded NdFeB magnets using the binder 3% wt. and 5% wt. rubber are respectively 4,70 g/cm 3 and 4.88 g/cm 3 . The result from BH- curve shows that the highest value of remanence (Br = 5.12 kGauss) is at sample with 3% wt. of rubber, but sample with 5% wt. of rubber has lowest value of remanance (Br = 4.40 kGauss). Based on the observation of the SEM photograph shown that the rubber material has been successfully covered the whole surface of the grain and fill some of the voids that are in the grain boundary. (paper)

  9. Physical and magnetic properties, microstructure of bonded magnet NdFeB prepared by using synthesis rubber

    Science.gov (United States)

    Suprapedi; Sardjono, P.; Muljadi

    2016-11-01

    The magnet permanent has been made by using NdFeB (NQP-B) powder with purity 99.90% and polymer rubber with purity 90%. This research was done to determine the effect of the polymer (rubber) composition as binder in the manufacture of bonded magnet NdFeB on physical properties, microstructure and magnetic properties. Bonded magnets are magnet material made from a mixture of magnetic powder as a filler and the polymer as a matrix material or as binder to bind the magnetic particles. The NdFeB (NQP-B) powder fractions of bonded magnets NdFeB investigated were as follows: a) 97 wt.% of NdFeB (NQP-B) and 3 wt.% of rubber,b) 95wt.% of NdFeB (NQP-B) and 5 wt.% of rubber, c) 93 wt.% of NdFeB (NQP-B) and 7 wt.% of rubber, d) 91 wt.% of NdFeB (NQP-B) and 9 wt.% of rubber. Both raw materials were mixed by using mixer until homogen with total weight about 16 g for each sample, then added 0.3 ml of catalyst and mixed again and put in dies mould and compacted at pressure 30 MPa, then dried for 2 hours at room temperature. The dried samples was characterized such as: bulk density measurement and magnetic properties by using BH-curve permeagraph. The bulk density values of the sample bonded NdFeB magnets using the binder 3% wt. and 5% wt. rubber are respectively 4,70 g/cm3 and 4.88 g/cm3. The result from BH- curve shows that the highest value of remanence (Br = 5.12 kGauss) is at sample with 3% wt. of rubber, but sample with 5% wt. of rubber has lowest value of remanance (Br = 4.40 kGauss). Based on the observation of the SEM photograph shown that the rubber material has been successfully covered the whole surface of the grain and fill some of the voids that are in the grain boundary.

  10. Synthesis, Characterization, and Magnetic Properties of Pure and EDTA-Capped NiO Nanosized Particles

    Directory of Open Access Journals (Sweden)

    H. T. Rahal

    2017-01-01

    Full Text Available The effect of ethylenediaminetetraacetic acid (EDTA as a capping agent on the structure, morphology, optical, and magnetic properties of nickel oxide (NiO nanosized particles, synthesized by coprecipitation method, was investigated. Nickel chloride hexahydrate and sodium hydroxide (NaOH were used as precursors. The resultant nanoparticles were characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, and scanning electron microscopy (SEM. XRD patterns showed that NiO have a face-centered cubic (FCC structure. The crystallite size, estimated by Scherrer formula, has been found in the range of 28–33 nm. It is noticed that EDTA-capped NiO nanoparticles have a smaller size than pure nanoparticles. Thus, the addition of 0.1 M capping agent EDTA can form a nucleation point for nanoparticles growth. The optical and magnetic properties were investigated by Fourier transform infrared spectroscopy (FTIR and UV-vis absorption spectroscopy (UV as well as electron paramagnetic resonance (EPR and magnetization measurements. FTIR spectra indicated the presence of absorption bands in the range of 402–425 cm−1, which is a common feature of NiO. EPR for NiO nanosized particles was measured at room temperature. An EPR line with g factor ≈1.9–2 is detected for NiO nanoparticles, corresponding to Ni2+ ions. The magnetic hysteresis of NiO nanoparticles showed that EDTA capping recovers the surface magnetization of the nanoparticles.

  11. Synthesis and magnetic properties of Ta/NdFeB-based composite microwires

    Energy Technology Data Exchange (ETDEWEB)

    Szary, P., E-mail: philipp.szary@uni.lu; Périgo, E. A.; Michels, A. [Physics and Materials Science Research Unit, University of Luxembourg, 162 Avenue de la Faïencerie, L-1511 Luxembourg, Grand Duchy of Luxembourg (Luxembourg); Luciu, I.; Duday, D.; Wirtz, T.; Choquet, P. [Science and Analysis of Materials (SAM), Centre de Recherche Public—Gabriel Lippmann, 41, rue du Brill, L-4422 Belvaux, Grand Duchy of Luxembourg (Luxembourg)

    2015-05-07

    Magnetic NdFeB-based microwire composites have been prepared by the direct current magnetron sputtering technique in a specifically designed sputtering chamber for thin-film deposition in wire geometry. As substrate wire material, we have employed steel and Ta. Annealing of the substrate wires during the deposition process was performed by ohmic heating through the application of a direct current. Samples were characterized by means of vibrating sample magnetometry (VSM) and scanning electron microscopy. Best properties have been encountered when using Ta wires as core (substrate) material. The VSM data show a dramatic impact of the current applied during the deposition process on the magnetic properties. For higher current values, i.e., higher annealing temperatures, the wires exhibit a reversal process that is typical for a two-phase system. Moreover, an increase of the coercive field (and remanent magnetization) is observed, which is ascribed to a modification of the magnetic phase present in the sample due to the annealing. We find an indication for the formation of a magnetic easy-axis direction which is azimuthally oriented around the wire axis.

  12. Synthesis and magnetic properties of bundled and dispersed Co3O4 nanowires

    International Nuclear Information System (INIS)

    Zhang, B.B.; Wang, P.F.; Xu, J.C.; Han, Y.B.; Jin, H.X.; Jin, D.F.; Peng, X.L.; Hong, B.; Li, J.; Yang, Y.T.; Gong, J.; Ge, H.L.; Wang, X.Q.

    2016-01-01

    Highlights: • Co 3 O 4 nanowires possessed the same diameter and the different interwires distance. • All samples possessed antiferromagnetism and superparamagnetism at high temperature. • The exchange bias effect was observed at low temperature. • The surface spin coupling restrained the surface effect of magnetic nanostructures. - Abstract: The magnetic Co 3 O 4 nanowires were synthesized using the templates of SBA-15, and then the well-dispersed nanowires (D-wires) were separated from the bundled ordered nanowires (B-wires) with the centrifugal technique. TEM images indicated that D-wires were highly dispersed Co 3 O 4 nanowires and B-wires existed in bundles. All samples possessed the antiferromagnetism and superparamagnetism at high temperature. After revealing the intrinsic magnetic properties of Co 3 O 4 nanowires with D-wires, the magnetic behavior of B-wires was discussed in detail, and then the magnetic interaction between neighboring nanowires could be deduced. The exchange bias effect from the body Co 3 O 4 antiferromagnetism and surface ferromagnetism was observed at low temperature. The magnetization of B-wires was higher than that of D-wires, which was attributed to the constraint of the surface spin coupling between the neighboring nanowires to the surface affect of nanostructures.

  13. Highly temperature responsive core-shell magnetic particles: synthesis, characterization and colloidal properties.

    Science.gov (United States)

    Rahman, Md Mahbubor; Chehimi, Mohamed M; Fessi, Hatem; Elaissari, Abdelhamid

    2011-08-15

    Temperature responsive magnetic polymer submicron particles were prepared by two step seed emulsion polymerization process. First, magnetic seed polymer particles were obtained by emulsion polymerization of styrene using potassium persulfate (KPS) as an initiator and divinylbenzne (DVB) as a cross-linker in the presence of oil-in-water magnetic emulsion (organic ferrofluid droplets). Thereafter, DVB cross-linked magnetic polymer particles were used as seed in the precipitation polymerization of N-isopropylacrylamide (NIPAM) to induce thermosensitive PNIPAM shell onto the hydrophobic polymer surface of the cross-linked magnetic polymer particles. To impart cationic functional groups in the thermosensitive PNIPAM backbone, the functional monomer aminoethylmethacrylate hydrochloride (AEMH) was used to polymerize with NIPAM while N,N'-methylenebisacrylamide (MBA) and 2, 2'-azobis (2-methylpropionamidine) dihydrochloride (V-50) were used as a cross-linker and as an initiator respectively. The effect of seed to monomer (w/w) ratio along with seed nature on the final particle morphology was investigated. Dynamic light scattering (DLS) results demonstrated particles swelling at below volume phase transition temperature (VPTT) and deswelling above the VPTT. The perfect core (magnetic) shell (polymer) structure of the particles prepared was confirmed by Transmission Electron Microscopy (TEM). The chemical composition of the particles were determined by thermogravimetric analysis (TGA). The effect of temperature, pH, ionic strength on the colloidal properties such as size and zeta potential of the micron sized thermo-sensitive magnetic particles were also studied. In addition, a short mechanistic discussion on the formation of core-shell morphology of magnetic polymer particles has also been discussed. Copyright © 2011 Elsevier Inc. All rights reserved.

  14. Enhancing the magnetic properties of magnetic nanoparticles

    DEFF Research Database (Denmark)

    Ahlburg, Jakob; Saura-Múzquiz, Matilde; Stingaciu, Marian

    with a similar magnetic performance. There are several different ways of enhancing magnetic properties of 3d magnetic compounds. This includes, size control, core-shell particles or mixing hard and soft magnetic materials together to achieve an exchange coupling between the compounds and enhancing the magnetic...... energy product. In order to control the particle size, a hydrothermal synthesis is preferred. This followed by reduction or the oxides into either core shell particles, or a mixture of magnetic oxides and a metallic phase.......Strong magnets with a high energy product are vital when optimizing the efficiency in the electric industry. But since the rare earth metals, normally used for making strong permanent magnets, are both expensive and difficult to mine, a great demand has come to cheaper types of magnets...

  15. 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.

  16. 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.

  17. Fe{sub 3}C/Fe nanoparticles with urea: Synthesis, structure and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaobai [College of Chemistry, Jilin University, Changchun, 130012 (China); School of Chemical and Pharmaceutical Engineering, Jilin Institute of Chemical Technology, Jilin, 132022 (China); Zhang, Daguang [Department of Orthopaedic Surgery, the First Hospital of Jilin University, Changchun, 130021 China (China); Ren, Xiaozhen; Gao, Jiajia [College of Chemistry, Jilin University, Changchun, 130012 (China); Han, Yu [Department of Chemistry, College of Science, Yanbian University, Yanji, 133002 China (China); Chen, Xiaodong [College of Chemistry, Jilin University, Changchun, 130012 (China); Shi, Zhan [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun, 130012 (China); Yang, Hua [College of Chemistry, Jilin University, Changchun, 130012 (China)

    2016-12-15

    Fe{sub 3}C/Fe nanocomposites were synthesized by a sol–gel method. Using urea as carbon source and reduce agent in the reaction process. The CTAB works as the surfactant and the bromine contained in CTAB plays a catalytic role. Appropriate choices of the amount of urea and CTAB, reaction temperature and time are very important to obtain high-quality of products. Above 650 °C, the precursor gel turned into the nanocomposites composed of iron carbide and iron. Their structures and magnetic properties are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). The possible formation mechanism of as-prepared nanostructures is discussed. - Highlights: • The Fe{sub 3}C/Fe composites were synthetized by sol–gel method. • Their structure, magnetic properties are researched by XRD, VSM and TEM. • The possible formation mechanisms of the composites is discussed.

  18. In situ X-ray powder diffraction, synthesis, and magnetic properties of InVO 3

    Science.gov (United States)

    Lundgren, Rylan J.; Cranswick, Lachlan M. D.; Bieringer, Mario

    2006-12-01

    We report the first synthesis and high-temperature in situ X-ray diffraction study of InVO 3. Polycrystalline InVO 3 has been prepared via reduction of InVO 4 using a carbon monoxide/carbon dioxide buffer gas. InVO 3 crystallizes in the bixbyite structure in space group Ia-3 (206) with a=9.80636(31) Å with In 3+/V 3+ disorder on the (8 b) and (24 d) cation sites. In situ powder X-ray diffraction experiments and thermal gravimetric analysis in a CO/CO 2 buffer gas revealed the existence of the metastable phase InVO 3. Bulk samples with 98.5(2)% purity were prepared using low-temperature reduction methods. The preparative methods limited the crystallinity of this new phase to approximately 225(50) Å. Magnetic susceptibility and neutron diffraction experiments suggest a spin-glass ground state for InVO 3.

  19. Synthesis and structural, magnetic and magnetotransport properties of permalloy powders containing nanoparticles prepared by arc discharge

    International Nuclear Information System (INIS)

    Prakash, Tushara; Williams, Grant V.M.; Kennedy, John; Murmu, Peter P.; Leveneur, Jérôme; Chong, Shen V.; Rubanov, Sergey

    2014-01-01

    Highlights: • New method of arc discharge used to synthesise permalloy containing nanoparticles. • The highest quality powders were made using a 78% Ni permalloy rod in N 2 . • The Saturation moment was slightly less and the coercive field was low (3 mT). • MR contributions from the spin-dependent tunneling between the particles. - Abstract: We report the synthesis of permalloy powders that were made using an arc-discharge method and with 78% or 45% Ni concentrations in N 2 or Ar. Our research was motivated by the fact that magnetic nanoparticles displaying large magnetoresistances are useful for magnetic field sensors applications. The permalloy powders contained some nanoparticles and the particle sizes ranged from 10 nm to ∼20 μm. The highest quality powders were made using a 78% Ni permalloy rod in N 2 where the coercivity was low (0.3 mT) and the saturation moment per formula unit was slightly less than that expected for the bulk compound. Magnetoresistance was observed in a cold pressed pellet where it is likely to be dominated by the ordinary magnetoresistance and spin-dependent tunneling between the particles

  20. Synthesis, thermionic emission and magnetic properties of (NdxGd1–x)B6

    International Nuclear Information System (INIS)

    Bao Li-Hong; Zhang Jiu-Xing; Zhou Shen-Lin; Tegus

    2011-01-01

    Polycrystalline rare-earth hexaborides (Nd x Gd 1–x )B 6 (x = 0, 0.2, 0.6, 0.8, 1) were prepared by the reactive spark plasma sintering (SPS) method using mixed powder of GdH 2 , NdH 2 and B. The effects of Nd doping on the crystal structure, the grain orientation, the thermionic emission and the magnetic properties of the hexaboride were investigated by X-ray diffraction, electron backscattered diffraction and magnetic measurements. It is found that all the samples sintered by the SPS method exhibit high densities (> 95%) and high values of Vickers hardness (2319 kg/mm 2 ). The values are much higher than those obtained in the traditional method. With the increase of Nd content, the thermionic emission current density increases from 11 to 16.30 A/cm 2 and the magnetic phase transition temperature increases from 5.85 to 7.95 K. Thus, the SPS technique is a suitable method to synthesize the dense rare-earth hexaborides with excellent properties. (interdisciplinary physics and related areas of science and technology)

  1. 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.

  2. Synthesis, structure and magnetic properties of DyAl2 nanoparticles

    International Nuclear Information System (INIS)

    Zhang, W.S.; Brueck, E.; Zhang, Z.D.; Tegus, O.; Li, W.F.; Si, P.Z.; Geng, D.Y.; Klaasse, J.C.P.; Buschow, K.H.J.

    2006-01-01

    DyAl 2 nanoparticles have been prepared by means of arc discharge in a mixture of argon and hydrogen gas. The structure of DyAl 2 nanoparticles is studied by means of X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. X-ray photoelectron spectroscopy shows that the as-prepared DyAl 2 nanoparticles are coated with a layer of Al 2 O 3 phase on the surface, and their sizes vary from 20 nm to about 100 nm. The DyAl 2 nanoparticles exhibit ferromagnetic properties that are different from bulk DyAl 2 compound. The gradual decrease of the magnetization with increasing temperature in a wide temperature range reveals the size distribution of the DyAl 2 nanoparticles. The magnetic-entropy changes are derived from the isothermal magnetization curves measured at different temperatures. The magnetic-entropy change of the DyAl 2 nanoparticles is lower than that of the bulk DyAl 2 material but has a broadened peak

  3. Synthesis, electrical and magnetic properties of sodium borosilicate glasses containing Co-ferrites nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Othman, H.A. [Department of Physics, Faculty of Science, Menoufia University, Shibin El-Kom 32511, Menoufia (Egypt); Eltabey, M.M. [Department of Basic Engineering Science, Faculty of Engineering, Menoufia University, Shibin El-Kom, Menoufia (Egypt); Department of Physics, Faculty of Science, Jazan University (Saudi Arabia); Ibrahim, Samia E.; El-Deen, L.M. Sharaf; Elkholy, M.M. [Department of Physics, Faculty of Science, Menoufia University, Shibin El-Kom 32511, Menoufia (Egypt)

    2017-02-01

    Co-ferrites nanoparticles that have been prepared by the co-precipitation method were added to sodium borosilicate (Na{sub 2}O–B{sub 2}O{sub 3}–SiO{sub 2}) glass matrix by the solid solution method and they were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and magnetization measurements. (XRD) revealed the formation of the Co-ferrite magnetic crystalline phase embedded in an amorphous matrix in all the samples. The investigated samples by (TEM) showed the formation of the cobalt ferrite nanoparticles with a spherical shape and highly monodispersed with an average size about 13 nm. IR data revealed that the BO{sub 3} and BO{sub 4} are the main structural units of these samples network. IR spectra of the investigated samples showed the characteristic vibration bands of Co-ferrite. Composition and frequency dependent dielectric properties of the prepared samples were measured at room temperature in the frequency range 100–100 kHz. The conductivity was found to increase with increasing cobalt ferrite content. The variations of conductivity and dielectric properties with frequency and composition were discussed. Magnetic hysteresis loops were traced at room temperature using VSM and values of saturation magnetization M{sub S} and coercive field H{sub C} were determined. The obtained results revealed that a ferrimagnetic behavior were observed and as Co-ferrite concentration increases the values of M{sub S} and H{sub C} increase from 2.84 to 8.79 (emu/g) and from 88.4 to 736.3 Oe, respectively.

  4. Synthesis, molecular structure and magnetic properties of a rhenium(IV) compound with catechol

    Science.gov (United States)

    Cuevas, A.; Geis, L.; Pintos, V.; Chiozzone, R.; Sanchíz, J.; Hummert, M.; Schumann, H.; Kremer, C.

    2009-03-01

    A novel Re(IV) complex containing catechol as ligand has been prepared and characterized. The crystal structure of (HNEt 3)(NBu 4)[ReCl 4(cat)]·H 2cat was determined. The rhenium ion presents a distorted octahedral geometry, being bonded to a bidentate catecholate group and four chloride anions. The magnetic properties of the complex were studied, a /2 D/ (the energy gap between ±3/2 and ±1/2 Kramers doublets) value of 190(10) cm -1. This is the largest /2 D/ value reported for Re(IV) up to now.

  5. A facile hydrothermal synthesis, characterization and magnetic properties of mesoporous CoFe{sub 2}O{sub 4} nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, M. Penchal, E-mail: reddy@nimte.ac.cn [Center for Advanced Materials, Qatar University, Doha 2713 (Qatar); Mohamed, A.M.A. [Center for Advanced Materials, Qatar University, Doha 2713 (Qatar); Department of Metallurgical and Materials Engineering, Faculty of Petroleum and Mining Engineering, Suez University, Suez 4372 (Egypt); Zhou, X.B.; Du, S.; Huang, Q. [Ningbo Institute of Materials Technology and Engineering (NIMTE), Chinese Academy of Sciences (CAS), Ningbo 315201, Zhejiang, RP China (China)

    2015-08-15

    Mesoporous CoFe{sub 2}O{sub 4} nanospheres with an average size of 180 nm were fabricated via a facile hydrothermal process using ethylene glycol as solvent and sodium acetate (NaAc) as electrostatic stabilizer. In this method, ethylene glycol plays a vital role in the formation of cobalt nanoospheres as a solvent and reducing agent. The structure and morphology of the prepared materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The nanospheres exhibited ferromagnetic properties with high saturation magnetization value of about 60.19 emu/g at room temperature. The BET surface area of the nanospheres was determined using the nitrogen absorption method. The porous CoFe{sub 2}O{sub 4} nanospheres displayed good magnetic properties, which may provide a very promising candidate for their applications in target drug delivery. - Highlights: • CoFe{sub 2}O{sub 4} nanospheres were prepared by hydrothermal synthesis for the first time. • Average grain size was found to be 180 nm. • Its structural, morphological, magnetic behavior was studied. • TEM observations confirmed the spherical morphology of the mesoporous ferrites.

  6. In situ synthesis of graphene/cobalt nanocomposites and their magnetic properties

    International Nuclear Information System (INIS)

    Ji Zhenyuan; Shen Xiaoping; Song You; Zhu Guoxing

    2011-01-01

    Graphene, which possesses unique nanostructure and excellent properties, is considered as a low cost alternative to carbon nanotubes in nanocomposites. In this study, we present a simple in situ approach for the deposition of cobalt (Co) nanoparticles onto surfaces of graphene sheets by hydrazine hydrate reduction. The as-synthesized composites were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, transmission electron microscopy (TEM) and thermogravimetry and differential scanning calorimetry. It was shown that the as-formed Co nanoparticles were densely and homogeneously deposited on the surfaces of the graphene sheets and as a result, the restacking of the as-reduced graphene sheets was effectively inhibited. Magnetic studies reveal that the graphene/Co nanocomposite displays ferromagnetic behavior with saturation magnetizations of 53.4 emu g -1 , remanent magnetization of 6.0 emu g -1 and coercivity of 226 Oe at room temperature, which make it promising for practical applications in future nanotechnology.

  7. Surfactant-assisted hydrothermal synthesis of CdS nanotips: optical and magnetic properties

    International Nuclear Information System (INIS)

    Mondal, Biswajit; Saha, Shyamal Kumar

    2012-01-01

    CdS nanotips with size 5–8 nm are synthesized by hydrothermal process using polyacrylamide (PAM) as surfactant. The shape of nanocrystals (NCs) changes from particles to nanorods or nanotips depending upon the amount of PAM used. Optical properties of the CdS NCs vary with hydrothermal temperature (T H ) due to formation of “S” vacancies. The Rietveld refinement of XRD data shows that “S” site occupancy decreases with increase in T H and amount of PAM indicating the formation of “S” vacancies. Size-dependent magnetic properties in these NCs indicate that the micron-size rods are diamagnetic in nature while the microrods ended with sharp tips show ferromagnetism even at room temperature. The origin of this ferromagnetism in nanotips is explained by the variation in density of “S” defects at the nanotips as well as in the nanorods. These ferromagnetic nanotips grown in the rods as side growth have potential applications in magnetic force microscopes.

  8. 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.

  9. 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.

  10. MnS spheres: Shape-controlled synthesis and its magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Kezhen [Institute of Catalysis for Energy and Environment, College of Chemistry and Chemical Engineering, Shenyang Normal University, Shenyang, 110034 (China); Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Nankai University, Tianjin, 300071 (China); State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, 430070 (China); Wang, Yan-Qin, E-mail: wangyanqin@tyut.edu.cn [Shanxi Key Lab. of Material Strength & Structural Impact, College of Mechanics, Taiyuan University of Technology, Taiyuan, 030024 (China); Rengaraj, Selvaraj, E-mail: srengaraj1971@yahoo.com [Department of Chemistry, College of Science, Sultan Qaboos University, Muscat, 123 (Oman); Al Wahaibi, Bushra [Department of Chemistry, College of Science, Sultan Qaboos University, Muscat, 123 (Oman); Mohamed Jahangir, A.R. [Biyaq Oil Field Services LLC, Mina Al Fahal, Muscat, 123 (Oman)

    2017-06-01

    Sphere-like MnS hierarchical microstructures were successfully synthesized by a simple hydrothermal approach, which are composed of the size tunable and self-assembled nanoparticles. These hierarchical microspheres are γ-MnS phase, which is confirmed by X-ray diffraction (XRD) results, and the stoichiometry of MnS microspheres is checked by XPS measurement. Morphological studies performed by scanning electron microscopy (SEM) method show that the as-prepared γ-MnS samples are hierarchical microspheres. The size and morphology of composed nanoparticles can be turned by the concentration of L-Cystein molecules. Here, L-Cystein not only plays a role of sulfur source but also capping agent. Furthermore, a rational mechanism about the formation and evolution of the products is proposed. The present work shows that the origin of the observed difference of magnetic properties is due to the morphology difference of MnS crystals. - Highlights: • Sphere-like MnS hierarchical microstructures were synthesized and characterized. • The size and morphology of MnS crystals can be turned by the concentration of L-Cystein molecules. • The morphology of MnS hierarchitectures exerts a remarkable effect on their magnetic property.

  11. Iron oxide nanoparticles: the Influence of synthesis method and size on composition and magnetic properties

    International Nuclear Information System (INIS)

    Carvalho, M.D.; Henriques, F.; Ferreira, L.P.; Godinho, M.; Cruz, M.M.

    2013-01-01

    Iron oxide nanoparticles with mean diameter ranging from 7 to 20 nm were synthesized using two routes: the precipitation method in controlled atmosphere and a reduction–precipitation method under air, in some cases followed by a hydrothermal treatment. The smallest nanoparticles were obtained by the reduction–precipitation method. In order to establish the composition of the iron oxide nanoparticles and its relation with size, the morphological, structural and magnetic properties of the prepared samples were investigated using X-ray diffraction, transmission electron microscopy, Mössbauer spectroscopy and SQUID magnetometry. The results allow to conclude that the nanoparticles can be essentially described as Fe 3−x O 4 , x decreasing with the particle size increase. The composition and magnetic behavior of the synthesized iron oxide nanoparticles are directly related with their size. The overall results are compatible with a core@shell structure model, where a magnetite core is surrounded by an oxidized magnetite layer (labeled as maghemite), the magnetite core dimension depending on the average particle size. - Graphical abstract: TEM images and Mössbauer spectroscopy spectra of Fe 3−x O 4 samples with different sizes. Highlights: ► Fe 3−x O 4 nanoparticles with a mean size between 7 and 20 nm were synthesized. ► The smallest nanoparticles were obtained by a reduction precipitation method, under air. ► The increase of particles size was succeeded using a hydrothermal treatment at 150 °C. ► The magnetic properties of the nanoparticles are directly related with their size

  12. Synthesis and magnetic properties of LiFePO4 substitution magnesium

    Science.gov (United States)

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

    2017-06-01

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

  13. 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

  14. Synthesis, characterization and magnetic properties of highly monodispersed PtNi nanoparticles

    International Nuclear Information System (INIS)

    Du, Juan-Juan; Yang, Yi; Zhang, Rong-Hua; Zhou, Xin-Wen

    2015-01-01

    In this paper, we report the controlled-synthesis of PtNi nanoparticles through galvanic displacement reaction and chemical reduction. The size, composition and morphology of the products are characterized by transmission electron microscopy (TEM), powder X-ray diffraction (XRD), energy dispersed X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analyses. The structure and composition of the PtNi nanoparticles can be controlled by adjusting the synthetic conditions. The possible formation mechanism is obtained from the academic analysis and experimental studies. The results of the magnetic measurement illustrate that the PtNi nanoparticles show a superparamagnetic behavior with a blocking temperature (T B ) about 8.0 K. - Highlights: • Highly monodispersed PtNi nanoparticles were synthesized by galvanic displacement reaction. • The formation of Pt nanocrystals was the foremost step because of its self-catalysis effect. • The PtNi nanoparticles show a superparamagnetic behavior with a T B about 8.0 K

  15. Microemulsion synthesis and magnetic properties of Fe{sub x}Ni{sub (1−x)} alloy nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Beygi, H., E-mail: hossein.beygi@stu-mail.um.ac.ir; Babakhani, A.

    2017-01-01

    This paper investigates synthesis of Fe{sub x}Ni{sub (1−x)} bimetallic nanoparticles by microemulsion method. Through studying the mechanism of nanoparticles formation, it is indicated that synthesis of nanoparticles took placed by simultaneous reduction of metal ions and so nanoparticles structure is homogeneous alloy. Fe{sub x}Ni{sub (1−x)} nanoparticles with different sizes, morphologies and compositions were synthesized by changing the microemulsion parameters such as water/surfactant/oil ratio, presence of co-surfactant and NiCl{sub 2}·6H{sub 2}O to FeCl{sub 2}·4H{sub 2}O molar ratio. Synthesized nanoparticles were characterized by transmission electron microscopy, particle size analysis, X-ray diffraction, atomic absorption and thermogravimetric analyses. The results indicated that, presence of butanol as co-surfactant led to chain-like arrangement of nanoparticles. Also, finer nanoparticles were synthesized by decreasing the amount of oil and water and increasing the amount of CTAB. The results of vibrating sample magnetometer suggested that magnetic properties of Fe{sub x}Ni{sub (1−x)} alloy nanoparticles were affected by composition, size and morphology of the particles. Spherical and chain-like Fe{sub x}Ni{sub (1−x)} alloy nanoparticles were superparamagnetic and ferromagnetic, respectively. Furthermore, higher iron in the composition of nanoparticles increases the magnetic properties. - Highlights: • Fe{sub x}Ni{sub (1−x)} alloy NPs synthesized by simultaneous metal ions reduction in microemulsion. • Finer NPs synthesized at lower amount of oil and water and higher amount of CTAB. • Chain-like Fe{sub x}Ni{sub (1−x)} NPs are ferromagnetic; higher aspect ratio, more magnetization. • Spherical Fe{sub x}Ni({sub 1−x)} NPs with smaller size (7 nm) are superparamagnetic. • Spherical Fe{sub x}Ni{sub (1−x)} nanoparticles with higher x had increased magnetic properties.

  16. Synthesis, magnetic and ethanol gas sensing properties of semiconducting magnetite nanoparticles

    Science.gov (United States)

    Al-Ghamdi, Ahmed A.; Al-Hazmi, Faten; Al-Tuwirqi, R. M.; Alnowaiser, F.; Al-Hartomy, Omar A.; El-Tantawy, Farid; Yakuphanoglu, F.

    2013-05-01

    The superparamagnetic magnetite (Fe3O4) nanoparticles with an average size of 7 nm were synthesized using a rapid and facile microwave hydrothermal technique. The structure of the magnetite nanoparticles was characterized by X-ray diffraction (X-ray), field effect scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). The prepared Fe3O4 was shown to have a cubic phase of pure magnetite. Magnetization hysteresis loop shows that the synthesized magnetite exhibits no hysteretic features with a superparamagnetic behavior. The ethanol gas sensing properties of the synthesized magnetite were investigated, and it was found that the responsibility time is less than 10 s with good reproducibility for ethanol sensor. Accordingly, it is evaluated that the magnetite nanoparticles can be effectively used as a solid state ethanol sensor in industrial commercial product applications.

  17. Solid-state synthesis, structural and magnetic properties of CoPd films

    Science.gov (United States)

    Myagkov, V. G.; Bykova, L. E.; Zhigalov, V. S.; Tambasov, I. A.; Bondarenko, G. N.; Matsynin, A. A.; Rybakova, A. N.

    2015-05-01

    The results of the investigation of the structural and magnetic properties of CoPd films with equiatomic composition have been presented. The films have been synthesized by vacuum annealing of polycrystalline Pd/Co and epitaxial Pd/α-Co(110) and Pd/β-Co(001) bilayer samples. It has been shown that, for all samples, the annealing to 400°C does not lead to the mixing of layers and the formation of compounds. A further increase in the annealing temperature results in the formation of a disordered CoPd phase at the Pd/Co interface, which is fully completed after annealing at 650°C. The epitaxial relationships between the disordered CoPd phase and the MgO(001) substrate are determined as follows: CoPd(110)<

  18. Hydrothermal synthesis of mixed zinc–cobalt ferrite nanoparticles: structural and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Coppola, P. [Univ. de Brasília, Complex Fluids Group, Instituto de Química (Brazil); Silva, F. G. da [Univ. de Brasília, Laboratório de Nanociência Ambiental e Aplicada - LNAA, Faculdade UnB Planaltina (Brazil); Gomide, G.; Paula, F. L. O. [Univ. de Brasília, Complex Fluids Group, Instituto de Física (Brazil); Campos, A. F. C. [Univ. de Brasília, Laboratório de Nanociência Ambiental e Aplicada - LNAA, Faculdade UnB Planaltina (Brazil); Perzynski, R. [Sorbonne Universités, UPMC Univ. Paris 06, CNRS, Laboratoire PHENIX (France); Kern, C. [Univ. de Brasília, Complex Fluids Group, Instituto de Química (Brazil); Depeyrot, J. [Univ. de Brasília, Complex Fluids Group, Instituto de Física (Brazil); Aquino, R., E-mail: reaquino@unb.br [Univ. de Brasília, Laboratório de Nanociência Ambiental e Aplicada - LNAA, Faculdade UnB Planaltina (Brazil)

    2016-05-15

    We synthesize Zn-substituted cobalt ferrite (Zn{sub x}Co{sub 1−x}Fe{sub 2}O{sub 4}, with 0 ≤ x ≤ 1) magnetic nanoparticles by a hydrothermal co-precipitation method in alkaline medium. The chemical composition is evaluated by atomic absorption spectroscopy and energy-dispersive X-ray spectroscopy techniques. The structure and morphology of the nanopaticles are investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. XRD Rietveld refinements reveal the cation distribution among the tetrahedral (A) and octahedral (B) sites. It shows that up to x ~0.5 zinc ions occupy preferably A-sites, above which Zn ions begin also a gradual occupancy of B-sites. TEM images show nanoparticles with different shapes varying from spheres, cubes, to octahedrons. Hysteresis loop properties are studied at 300 and 5 K. These properties are strongly influenced by the Zn and Co proportion in the nanoparticle composition. At 300 K, only samples with high Co content present hysteresis. At 5 K, the reduced remanent magnetization ratio (M{sub R}/M{sub S}) and the coercivity (H{sub C}) suggest that nanoparticles with x < 0.5 have cubic anisotropy. A kink on the hysteresis loop, close to the remanence, is observed at low temperature. This feature is presumably associated to interplay between hard and soft anisotropy regimes in the powder samples.Graphical Abstract.

  19. Synthesis, characterization and magnetic properties of a manganese (II) silicate containing frustrated S=5/2 zig–zag ladders

    International Nuclear Information System (INIS)

    Brandão, P.; Santos, A.M. dos; Paixão, L.S.; Reis, M.S.

    2014-01-01

    The hydrothermal synthesis, structural characterization and magnetic properties of a manganese silicate with ideal formula of NaMn 2 Si 3 O 8 (OH) is reported. This compound is a synthetic analog to the naturally occurring mineral Serandite. The crystal structure comprises MnO 6 octahedra and SiO 4 tetrahedra. The MnO 6 share four edges with neighboring octahedra forming double chains. These chains are connected by silicate chains Si 3 O 8 (OH) resulting in an open framework structure with six-member ring channels where sodium ions are located. From the magnetic point of view, the intra-chain exchange between neighboring S=5/2 manganese ions is weak, partly due to the distortion observed in the octahedra, but also due to the frustrated topology of the chain. A successful fitting of the magnetic susceptibility was obtained by considering a double chain numerical model with Monte Carlo derived empirical parameters. -- Graphical abstract: A manganese silicate prepared hydrothermally with formula NaMn 2 Si 3 O 8 (OH) possessing the structure of the mineral Serandite contains doubled chains of edge-sharing MnO 6 octahedra. The magnetic susceptibility was measured and shows an antiferromagnetic behavior. Highlights: • Characterization of a synthetic analog to the mineral Serandite: NaMn 2 Si 3 O 8 (OH). • Fitting of the magnetic susceptibility considering a classical regular chain. • Weak metal–oxygen–metal super-exchange interactions; antiferromagnetic in nature. • Elevated degree of frustration along the chain, without sign of interchain ordering

  20. Synthesis of magnetic polymeric microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Gervald, A Yu; Gritskova, Inessa A; Prokopov, Nikolai I [M.V. Lomonosov Moscow State Academy of Fine Chemical Technology, Moscow (Russian Federation)

    2010-05-13

    The key types of magnetic polymeric microspheres are considered. Methods of synthesis of different types of magnetic nanoparticles and of preparation of stable magnetic fluids on their basis are outlined. The overview of the methods for the manufacture of magnetic polymeric microspheres is presented. The effect of the synthesis conditions on the characteristics of magnetic polymeric microspheres such as the diameter and the particle size distribution and the content of magnetic material is discussed by particular examples. The application fields of magnetic polymeric microspheres are briefly surveyed.

  1. Synthesis of magnetic polymeric microspheres

    International Nuclear Information System (INIS)

    Gervald, A Yu; Gritskova, Inessa A; Prokopov, Nikolai I

    2010-01-01

    The key types of magnetic polymeric microspheres are considered. Methods of synthesis of different types of magnetic nanoparticles and of preparation of stable magnetic fluids on their basis are outlined. The overview of the methods for the manufacture of magnetic polymeric microspheres is presented. The effect of the synthesis conditions on the characteristics of magnetic polymeric microspheres such as the diameter and the particle size distribution and the content of magnetic material is discussed by particular examples. The application fields of magnetic polymeric microspheres are briefly surveyed.

  2. Synthesis and room-temperature ferromagnetic properties of single-crystalline Co-doped SnO2 nanocrystals via a high magnetic field

    International Nuclear Information System (INIS)

    Xu Yongbin; Tang Yongjun; Li Chuanjun; Cao Guanghui; Ren Weili; Xu Hui; Ren Zhongming

    2009-01-01

    The magnetic field-assisted approach has been used in the synthesis of Co-doped SnO 2 diluted magnetic semiconductor nanocrystals. By annealing under the condition with or without magnetic field, 1D growth of the nanostructures can be induced, and the magnetic properties of the obtained nanocrystals are improved. Various techniques such as X-ray diffraction (XRD), transmission electron microscope (TEM), UV-visible spectrometry (UV-vis), Raman spectrometry and vibrating sample magnetometer (VSM) have been used to characterize the obtained products. The results show that the magnetic field holds important effects on the crystal growth of the Co-doped SnO 2 nanostructures, and improvement of magnetic properties. The intrinsic reasons are discussed.

  3. Synthesis, characterization, magnetic and electrochemical properties of a new 3D hexa-copper-substituted germanotungstate

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yanzhou; Luo, Jie; Zhang, Yanting [Institute of Molecular and Crystal Engineering, Henan Key Lab of Polyoxometalate Chemistry, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); Zhao, Junwei, E-mail: zhaojunwei@henu.edu.cn [Institute of Molecular and Crystal Engineering, Henan Key Lab of Polyoxometalate Chemistry, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); Basic Experiment Teaching Center, Henan University, Kaifeng, Henan 475004 (China); Chen, Lijuan, E-mail: ljchen@henu.edu.cn [Institute of Molecular and Crystal Engineering, Henan Key Lab of Polyoxometalate Chemistry, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Ma, Pengtao; Niu, Jingyang [Institute of Molecular and Crystal Engineering, Henan Key Lab of Polyoxometalate Chemistry, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China)

    2013-09-15

    An inorganic–organic hybrid hexa-copper-substituted germanotungstate Na{sub 2}[Cu(dap){sub 2}]{sub 2}[Cu(dap){sub 2}] ([Cu{sub 6}(H{sub 2}O){sub 2}(dap){sub 2}][B-α-GeW{sub 9}O{sub 34}]{sub 2})·4H{sub 2}O (1) (dap=1,2-diaminopropane) has been hydrothermally prepared and characterized by elemental analyses, inductively coupled plasma atomic emission spectrometry (ICP–AES) analyses, IR spectra, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and single-crystal X-ray diffraction. 1 displays the six-connected 3D network with the long topological (O′Keefe) vertex symbol is 4·4·6{sub 4}·4·4·4·4·6{sub 4}·4·4·4·6{sub 4}·4·4·4 and the short vertex (Schläfli) symbol of 4{sup 12}6{sup 3}. Magnetic measurements indicate that there are the overall ferromagnetic exchange interactions in the belt-like hexa-Cu{sup II} cluster in 1. Furthermore, the electrochemical behavior and electrocatalysis of 1 modified carbon paste electrode (1-CPE) have been studied. The reductions of nitrite, bromate and hydrogen peroxide are principally mediated by the W{sup VI}-based wave. - Graphical abstract: A hexa-Cu{sup II} sandwiched germanotungstate has been synthesized and structurally characterized. The magnetic, solid-state electrochemical and electrocatalytic properties have been investigated. Display Omitted - Highlights: • Transition-metal substituted polyoxometalates. • Hexa-copper-substituted germanotungstate. • Six-connected 3D network. • Electrocatalytic reduction of nitrite, bromate and hydrogen peroxide.

  4. Synthesis, characterization, magnetic and electrochemical properties of a new 3D hexa-copper-substituted germanotungstate

    International Nuclear Information System (INIS)

    Li, Yanzhou; Luo, Jie; Zhang, Yanting; Zhao, Junwei; Chen, Lijuan; Ma, Pengtao; Niu, Jingyang

    2013-01-01

    An inorganic–organic hybrid hexa-copper-substituted germanotungstate Na 2 [Cu(dap) 2 ] 2 [Cu(dap) 2 ] ([Cu 6 (H 2 O) 2 (dap) 2 ][B-α-GeW 9 O 34 ] 2 )·4H 2 O (1) (dap=1,2-diaminopropane) has been hydrothermally prepared and characterized by elemental analyses, inductively coupled plasma atomic emission spectrometry (ICP–AES) analyses, IR spectra, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and single-crystal X-ray diffraction. 1 displays the six-connected 3D network with the long topological (O′Keefe) vertex symbol is 4·4·6 4 ·4·4·4·4·6 4 ·4·4·4·6 4 ·4·4·4 and the short vertex (Schläfli) symbol of 4 12 6 3 . Magnetic measurements indicate that there are the overall ferromagnetic exchange interactions in the belt-like hexa-Cu II cluster in 1. Furthermore, the electrochemical behavior and electrocatalysis of 1 modified carbon paste electrode (1-CPE) have been studied. The reductions of nitrite, bromate and hydrogen peroxide are principally mediated by the W VI -based wave. - Graphical abstract: A hexa-Cu II sandwiched germanotungstate has been synthesized and structurally characterized. The magnetic, solid-state electrochemical and electrocatalytic properties have been investigated. Display Omitted - Highlights: • Transition-metal substituted polyoxometalates. • Hexa-copper-substituted germanotungstate. • Six-connected 3D network. • Electrocatalytic reduction of nitrite, bromate and hydrogen peroxide

  5. Synthesis, structural, dielectric and magnetic properties of polyol assisted copper ferrite nano particles

    Energy Technology Data Exchange (ETDEWEB)

    Pavithradevi, S. [Assistant Professor, Department of Physics, Park College of Engineering and Technology, Coimbatore (India); Suriyanarayanan, N., E-mail: madurasuri2210@yahoo.com [Prof & Head, Department of Physics, Government College of Technology, Coimbatore (India); Boobalan, T. [Lecturer, Department of Physics, PSG Polytechnic College, Coimbatore (India)

    2017-03-15

    Nanocrystalline copper ferrite CuFe{sub 2}O{sub 4} is synthesized by co-precipitation method in ethylene glycol as chelating agent, using sodium Hydroxide as precipitator at pH 8. The as synthesized CuFe{sub 2}O{sub 4} is annealed at temperatures of 350 °C, 700 °C, and 1050 °C for 2 h respectively. The thermal analysis of the synthesized sample is done by TG technique. It is shown that at 260 °C ethylene glycol has evaporated completely and after 715 °C, spinel ferrite is formed with a cubic structure. The calculated lattice parameters are in agreement with the reported values. FTIR spectra of CuFe{sub 2}O{sub 4} nano particles are as synthesized and annealed at 1050 °C and recorded between 400 cm{sup −1} and 4000 cm{sup −1}. It shows that when the temperature increases ethylene glycol gradually evaporates. Finally, nano crystalline single phase spinel ferrite is obtained. X-ray diffraction (XRD) and electron diffraction (EDS) studies show that the sample is indexed as the face centered cubic spinel structure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that the particles are flaky and spherical with the crystallite size in the range of 25–34 nm. From the dielectric studies, the dielectric constant decreases as the frequency increases. Low value of dielectric loss at higher frequencies suggests that the material is suitable for high frequency applications. AC conductivity increases with frequency. The magnetic properties of the samples are measured using a vibrating sample magnetometer (VSM) at room temperature, which shows that the sample exhibited a typical super paramagnetic behavior at low temperature. The saturation magnetization, remanant magnetism, and coercivity increases with applied field. - Highlights: • Complete removal of hematite phase along with ethylene glycol at 1050 °C. • Large decrease in particle sizes noticed along with ethylene glycol. • Ethylene glycol improves purity of the

  6. Bioinspired synthesis of magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    David, Anand [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    The synthesis of magnetic nanoparticles has long been an area of active research. Magnetic nanoparticles can be used in a wide variety of applications such as magnetic inks, magnetic memory devices, drug delivery, magnetic resonance imaging (MRI) contrast agents, and pathogen detection in foods. In applications such as MRI, particle uniformity is particularly crucial, as is the magnetic response of the particles. Uniform magnetic particles with good magnetic properties are therefore required. One particularly effective technique for synthesizing nanoparticles involves biomineralization, which is a naturally occurring process that can produce highly complex nanostructures. Also, the technique involves mild conditions (ambient temperature and close to neutral pH) that make this approach suitable for a wide variety of materials. The term 'bioinspired' is important because biomineralization research is inspired by the naturally occurring process, which occurs in certain microorganisms called 'magnetotactic bacteria'. Magnetotactic bacteria use biomineralization proteins to produce magnetite crystals having very good uniformity in size and morphology. The bacteria use these magnetic particles to navigate according to external magnetic fields. Because these bacteria synthesize high quality crystals, research has focused on imitating aspects of this biomineralization in vitro. In particular, a biomineralization iron-binding protein found in a certain species of magnetotactic bacteria, magnetospirillum magneticum, AMB-1, has been extracted and used for in vitro magnetite synthesis; Pluronic F127 gel was used to increase the viscosity of the reaction medium to better mimic the conditions in the bacteria. It was shown that the biomineralization protein mms6 was able to facilitate uniform magnetite synthesis. In addition, a similar biomineralization process using mms6 and a shorter version of this protein, C25, has been used to synthesize cobalt ferrite

  7. Synthesis and structural, magnetic, thermal, and transport properties of several transition metal oxides and aresnides

    Energy Technology Data Exchange (ETDEWEB)

    Das, Supriyo [Iowa State Univ., Ames, IA (United States)

    2010-01-01

    Oxide compounds containing the transition metal vanadium (V) have attracted a lot of attention in the field of condensed matter physics owing to their exhibition of interesting properties including metal-insulator transitons, structural transitions, ferromagnetic and an- tiferromagnetic orderings, and heavy fermion behavior. Binary vanadium oxides VnO2n-1 where 2 ≤ n ≤ 9 have triclinic structures and exhibit metal-insulator and antiferromagnetic transitions.[1–6] The only exception is V7O13 which remains metallic down to 4 K.[7] The ternary vanadium oxide LiV2O4 has the normal spinel structure, is metallic, does not un- dergo magnetic ordering and exhibits heavy fermion behavior below 10 K.[8] CaV2O4 has an orthorhombic structure[9, 10] with the vanadium spins forming zigzag chains and has been suggested to be a model system to study the gapless chiral phase.[11, 12] These provide great motivation for further investigation of some known vanadium compounds as well as to ex- plore new vanadium compounds in search of new physics. This thesis consists, in part, of experimental studies involving sample preparation and magnetic, transport, thermal, and x- ray measurements on some strongly correlated eletron systems containing the transition metal vanadium. The compounds studied are LiV2O4, YV4O8, and YbV4O8. The recent discovery of superconductivity in RFeAsO1-xFx (R = La, Ce, Pr, Gd, Tb, Dy, Sm, and Nd), and AFe2As2 (A = Ba, Sr, Ca, and Eu) doped with K, Na, or Cs at the A site with relatively high Tc has sparked tremendous activities in the condensed matter physics community and a renewed interest in the area of superconductivity as occurred following the discovery of the layered cuprate high Tc superconductors in 1986. To discover more supercon- ductors

  8. 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.

  9. Large-scale synthesis of Ni-Ag core-shell nanoparticles with magnetic, optical and anti-oxidation properties

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chung-Che; Chen, Dong-Hwang [Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan 701, Taiwan (China)

    2006-07-14

    The large-scale synthesis and characterization of Ni-core/Ag-shell (Ni at Ag) nanoparticles by the successive hydrazine reduction of nickel chloride and silver nitrate in ethylene glycol using polyethyleneimine (PEI) as a protective agent are described. The resultant Ni at Ag nanoparticles had a mean core diameter of 6.2 nm and a shell thickness of 0.85 nm, without significant change in the nickel concentration of 0.25-25 mM for the Ag coating. Also, both Ni cores and Ag nanoshells had an fcc structure and PEI was capped on the particle surface. X-ray photoelectron spectroscopy analysis confirmed that the Ni cores were fully covered by Ag nanoshells. In addition, the Ni at Ag nanoparticles exhibited a characteristic absorption band at 430 nm and were nearly superparamagnetic. Based on the weight of Ni cores, the saturation magnetization (M{sub s}), remanent magnetization (M{sub r}) and coercivity (H{sub c}) were obtained as 17.2 emu g{sup -1}, 4.0 emu g{sup -1} and 81 Oe, respectively. Furthermore, the resultant Ni at Ag nanoparticles exhibited better anti-oxidation properties than Ni nanoparticles did due to the protection of the Ag nanoshells.

  10. Synthesis of magnetic graphene oxide–TiO{sub 2} and their antibacterial properties under solar irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Ying-Na [College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082 (China); Ou, Xiao-Ming [China National Engineering Research Center for Agrochemicals, Hunan Research Institute of Chemical Industry, Changsha 410014 (China); Zeng, Guang-Ming [College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082 (China); Gong, Ji-Lai, E-mail: jilaigong@gmail.com [College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082 (China); Deng, Can-Hui; Jiang, Yan; Liang, Jie; Yuan, Gang-Qiang; Liu, Hong-Yu; He, Xun [College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082 (China)

    2015-07-15

    Highlights: • Magnetic graphene oxide–TiO{sub 2} (MGO–TiO{sub 2}) composites were synthesized. • MGO–TiO{sub 2} had excellent antibacterial activity toward Escherichia coli. • MGO–TiO{sub 2} could effectively and rapidly separate from aqueous solution. • Carbonates and phosphates significantly reduced the bacterial survival rate. - Abstract: Titanium dioxide (TiO{sub 2}) has been intensively researched and increasingly used as antibacterial agent, but it suffers from separation inconvenience. Its effective removal from water after reaction while maintaining its high antibacterial activity becomes necessary. In this work, it was the first time the magnetic graphene oxide–TiO{sub 2} (MGO–TiO{sub 2}) composites were prepared through a simple synthesis method. The results indicated that MGO–TiO{sub 2} exhibited a good antibacterial activity against Escherichia coli. MGO–TiO{sub 2} was found to almost completely inactivate the E. coli within 30 min under solar irradiation. The effect of inorganic ions present in E. coli suspension was also evaluated. Compared with other ions, HCO{sub 3}{sup −} and HPO{sub 4}{sup 2−} had a greater influence on the antibacterial property.

  11. Hydrothermal synthesis, off-axis electron holography and magnetic properties of Fe3O4 nanoparticles

    DEFF Research Database (Denmark)

    Almeida, Trevor P.; Muxworthy, Adrian R.; Williams, Wyn

    2014-01-01

    The hydrothermal synthesis of Fe3O4 nanoparticles (NPs) (<50 nm) from mixed FeCl3 / FeCl2 precursor solution at pH ~ 12 has been confirmed using complementary characterisation techniques of transmission electron microscopy and X-ray diffractometry. Off-axis electron holography allowed for visuali......The hydrothermal synthesis of Fe3O4 nanoparticles (NPs) (holography allowed...

  12. Effect of the synthesis conditions on the magnetic and electrical properties of the BaFeO3-x oxide: A metamagnetic behavior

    International Nuclear Information System (INIS)

    Gil de Muro, Izaskun; Insausti, Maite; Lezama, Luis; Rojo, Teofilo

    2005-01-01

    The BaFeO 2.95 oxide has been obtained from thermal decomposition of the [BaFe(C 3 H 2 O 4 ) 2 (H 2 O) 4 ] metallo-organic precursor at 800 deg. C under atmospheric oxygen pressure as small and homogeneous particles. From electronic paramagnetic resonance data, a metallic behavior in the 230-130K temperature range has been observed. Magnetic measurements confirm the existence of a ferro-antiferromagnetic transition at 178K. The magnetic properties of the BaFeO 2.95 oxide are strongly dependent on both temperature and magnetic field with a metamagnetic behavior. The synthesis conditions play an important role on the morphology and the electrical and magnetic properties. The syntherization of the sample produces a dramatic change in the transport properties and the existence of conductivity disappears

  13. Synthesis and magnetic properties of rare-earth free MnBi alloy: A high-energy hard magnetic material

    Science.gov (United States)

    Sharma, Sanjeev Kumar; Prakash, H. R.; Ram, S.; Pradhan, D.

    2018-04-01

    MnBi is a rare-earth free high-energy magnetic material useful for the permanent magnet based devices. In a simple method, a MnBi alloy was prepared by arc melting method using Mn and Bi metals in 60:40 atomic ratio. In terms of the X-ray diffraction, a crystalline MnBi phase is formed with Bi as impurity phase of the as-prepared alloy. FESEM image of chemically etched sample shows small grains throughout the alloy. SEAD pattern and lattice image were studied to understand the internal microstructure of the alloy. The thermomagnetic curves measured in ZFC-FC cycles over 5-380 K temperatures at 500 Oe field, shows the induced magnetization of 5-25 % in the sample. The coercivity values, 7.455 kOe (13.07 emu/g magnetization) at 380 K, and 5.185k Oe (14.75 emu/g magnetization) at 300 K, are observed in the M-H hysteresis loops. A decreased value 0.181kOe (18.05 emu/g magnetization) appears at 100 K due to the change in the magnetocrystalline anisotropy. The results are useful to fabricate small MnBi magnets for different permanent magnets based devices.

  14. Synthesis and magnetic properties of hexagonal Y(Mn,Cu)O3 multiferroic materials

    International Nuclear Information System (INIS)

    Jeuvrey, L.; Peña, O.; Moure, A.; Moure, C.

    2012-01-01

    Single-phase hexagonal-type solid solutions based on the multiferroic YMnO 3 material were synthesized by a modified Pechini process. Copper doping at the B-site (YMn 1−x Cu x O 3 ; x 1+y MnO 3 ; y 3+ two-dimensional lattice. The magnetic transition at T N decreases from 70 K down to 49 K, when x(Cu) goes from 0 to 15 at%. Weak ferromagnetic Mn 3+ –Mn 4+ interactions created by the substitution of Mn 3+ by Cu 2+ , are visible through the coercive field and spontaneous magnetization but do not modify the overall magnetic frustration. Presence of Mn 3+ –Mn 4+ pairs leads to an increase of the electrical conductivity due to thermally-activated small-polaron hopping mechanisms. Results show that local ferromagnetic interactions can coexist within the frustrated state in the hexagonal polar structure. - Highlights: ► Hexagonal-type solid solutions of Y(Mn,Cu)O 3 synthesized by Pechini process. ► Chemical substitution at B site inhibits geometrical magnetic frustration. ► Magnetic transition decreases with Cu-doping. ► Local ferromagnetic Mn–Mn interactions coexist with the frustrated state.

  15. Poly(o-phenylenediamine)/NiCoFe{sub 2}O{sub 4} nanocomposites: Synthesis, characterization, magnetic and dielectric properties

    Energy Technology Data Exchange (ETDEWEB)

    Kannapiran, Nagarajan [PG and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India); Muthusamy, Athianna, E-mail: muthusrkv@gmail.com [PG and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India); Chitra, Palanisamy; Anand, Siddeswaran [PG and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India); Jayaprakash, Rajan [Nanotechnology Laboratory, Department of Physics, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India)

    2017-02-01

    In this study, poly(o-phenylenediamine) (PoPD)/NiCoFe{sub 2}O{sub 4} nanocomposites were synthesized by in-situ oxidative chemical polymerization method with different amount of NiCoFe{sub 2}O{sub 4} nanoparticles. The NiCoFe{sub 2}O{sub 4} nanoparticles were prepared by auto-combustion method. The structural, morphological, thermal properties of the synthesized PoPD/NiCoFe{sub 2}O{sub 4} nanocomposites were characterized by fourier transform infrared spectrum (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Magnetic properties of NiCoFe{sub 2}O{sub 4} nanoparticles and PoPD/NiCoFe{sub 2}O{sub 4} nanocomposites were studied by vibrating sample magnetometer (VSM). The FTIR and XRD techniques were used to confirm the formation of PoPD/NiCoFe{sub 2}O{sub 4} nanocomposites. The average crystalline size of NiCoFe{sub 2}O{sub 4} nanoparticles and PoPD/NiCoFe{sub 2}O{sub 4} nanocomposites were calculated from XRD. From the SEM analysis, spherical morphology of the PoPD was confirmed. The TGA results showed that the NiCoFe{sub 2}O{sub 4} nanoparticles have improved the thermal stability of PoPD. Dielectric properties of PoPD/NiCoFe{sub 2}O{sub 4} nanocomposites at different temperatures have been carried in the frequency range 50 Hz to 5 MHz. - Highlights: • Auto-combustion method was support to achieve less particle size. • Green synthesis of PoPD and nanocomposites by in-situ oxidative chemical polymerization method. • For the first time, PoPD incorporated with NiCoFe{sub 2}O{sub 4} nanoparticles. • Ferrite content affects the magnetic and dielectric properties of the nanocomposites.

  16. Synthesis and magnetic properties of heteronuclear 3d-4f compound

    International Nuclear Information System (INIS)

    Cristovao, B.; Ferenc, W.

    2007-01-01

    A novel heteronuclear 3d-4f compound having formula NdCu 3 L 3 ·13H 2 O (where H 3 L = Schiff base derived from 5-bromosalicylaldehyde and glycylglycine and L 3 = C 11 H 8 N 2 O 4 Br) was obtained. It was characterized by elemental and thermal analyses and magnetic measurements. The Cu(II)-Nd(III) compound is stable up to 323 K. During dehydration process the water molecules are lost in two stages. The magnetic susceptibility data for this complex change with temperature according to the Curie-Weiss law with Θ = -35 K. The magnetic moment values decrease from 5.00μ B at 303 K to 4.38μB at 76 K. (author)

  17. Synthesis, crystal structure and magnetic properties of an alternating manganese chain

    International Nuclear Information System (INIS)

    Ramos Silva, Manuela; Matos Beja, Ana; Antonio Paixao, Jose; Martin-Gil, Jesus

    2006-01-01

    A new 1D complex has been prepared and characterized. X-ray single crystal structure confirms that the Mn(II) ions assemble in alternating chains with Mn-Mn distances of 3.8432(13) and 4.4428(14) A. A 3D network of hydrogen bonds links the chains together. The temperature dependence of the magnetic susceptibility reveals that this compound undergoes a magnetic transition and exhibits an antiferromagnetic interaction in the low-temperature phase with two alternating exchange interactions of -2.32(1) and -5.55(1) cm -1 . - Graphical abstract: Portion of the dimeric manganese chain showing the two alternating exchange interactions paths

  18. Nitrocyclopropanes: synthesis and properties

    Energy Technology Data Exchange (ETDEWEB)

    Averina, Elena B; Yashin, N V; Kuznetsova, Tamara S; Zefirov, Nikolai S [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

    2009-10-31

    State-of-the-art data on the methods of synthesis, properties and transformations of nitro- and- dinitrocyclopropanes of different structure is generalized and described systematically. The attention is focused on stereoselective cyclopropanation methods, new approaches to the synthesis of natural products and their synthetic analogues with diversified biological activities, in particular, of aminocyclopropane acids based on nitrocyclopropanes, and the formation of structures of energetic compounds.

  19. Synthesis, crystal structure and magnetic properties of [Cu(mal)(abpt ...

    African Journals Online (AJOL)

    Complex 1 consist of a neutral mononuclear [Cu(mal)(abpt)(H2O)] unit and water molecule of crystallization in a distorted square pyramidal coordination sphere, while complex 2 is viewed as being made up of [Cu(sq)(abpt)2] units with the squarato ligand bridging the two copper(II) cations. Variable temperature magnetic ...

  20. Synthesis and magnetic properties of a 1-D helical chain derived ...

    Indian Academy of Sciences (India)

    mounted on the tip of a glass pin using mineral oil and placed in the cold .... applied magnetic field of 0.5 Tesla, between 2–300 K. (figure 4). .... edges CSIR for financial support. ... Seo J S, Whang D, Lee H, Jun S I, Oh J, Jeon Y J and. Kim K ...

  1. Synthesis, structure and magnetic properties of the one-dimensional bimetallic oxide [Cu(terpy)Mo2O7

    International Nuclear Information System (INIS)

    Burkholder, Eric; Gabriel Armatas, N.; Golub, Vladimir; O'Connor, Charles J.; Zubieta, Jon

    2005-01-01

    The hydrothermal reaction of Cu(CH 3 CO 2 ) 2 .H 2 O, Na 2 MoO 4 and terpyridine at 140 deg. C for 48 h yields [Cu(terpy)Mo 2 O 7 ] (1), a bimetallic one-dimensional oxide. The structure consists of ruffled chains of edge- and corner-sharing {MoO 5 } square pyramids, decorated with {CuN 3 O 2 } '4+1' axially distorted square pyramids. The Cu(II) polyhedra are disposed so as to produce an alternating pattern of Cu-Cu distances across the {Mo 2 O 2 } rhombi of the chain of 6.25 and 6.82 A. This structural feature is reflected in the magnetic properties which are characteristic of a dimer rather than a linear chain, consistent with an alternating antiferromagnetic Heisenberg chain. -- Graphical abstract: Hydrothermal synthesis provided the one-dimensional bimetallic oxide [Cu(terpy)Mo 2 O 7 ], a material consisting of a zig-zag {Mo 2 O 7 } n 2 n - chain, decorated with {Cu(terpy)} 2+ groups exhibiting alternating short-long Cu-Cu distances between copper sites

  2. Synthesis and magnetic properties of hexagonal Y(Mn,Cu)O{sub 3} multiferroic materials

    Energy Technology Data Exchange (ETDEWEB)

    Jeuvrey, L., E-mail: laurent.jeuvrey@univ-rennes1.fr [Sciences Chimiques de Rennes, UMR-CNRS 6226, Universite de Rennes 1, 35042 Rennes cedex (France); Pena, O. [Sciences Chimiques de Rennes, UMR-CNRS 6226, Universite de Rennes 1, 35042 Rennes cedex (France); Moure, A.; Moure, C. [Electroceramics Department, Instituto de Ceramica y Vidrio, CSIC, C/Kelsen 5, 28049, Madrid (Spain)

    2012-03-15

    Single-phase hexagonal-type solid solutions based on the multiferroic YMnO{sub 3} material were synthesized by a modified Pechini process. Copper doping at the B-site (YMn{sub 1-x}Cu{sub x}O{sub 3}; x<0.15) and self-doping at the A-site (Y{sub 1+y}MnO{sub 3}; y<0.10) successfully maintained the hexagonal structure. Self-doping was limited to y(Y)=2 at% and confirmed that excess yttrium avoids formation of ferromagnetic manganese oxide impurities but creates vacancies at the Mn site. Chemical substitution at the B-site inhibits the geometrical frustration of the Mn{sup 3+} two-dimensional lattice. The magnetic transition at T{sub N} decreases from 70 K down to 49 K, when x(Cu) goes from 0 to 15 at%. Weak ferromagnetic Mn{sup 3+}-Mn{sup 4+} interactions created by the substitution of Mn{sup 3+} by Cu{sup 2+}, are visible through the coercive field and spontaneous magnetization but do not modify the overall magnetic frustration. Presence of Mn{sup 3+}-Mn{sup 4+} pairs leads to an increase of the electrical conductivity due to thermally-activated small-polaron hopping mechanisms. Results show that local ferromagnetic interactions can coexist within the frustrated state in the hexagonal polar structure. - Highlights: Black-Right-Pointing-Pointer Hexagonal-type solid solutions of Y(Mn,Cu)O{sub 3} synthesized by Pechini process. Black-Right-Pointing-Pointer Chemical substitution at B site inhibits geometrical magnetic frustration. Black-Right-Pointing-Pointer Magnetic transition decreases with Cu-doping. Black-Right-Pointing-Pointer Local ferromagnetic Mn-Mn interactions coexist with the frustrated state.

  3. Synthesis, structure, and magnetic properties of two 1-D helical coordination polymeric Cu(II) complexes

    Science.gov (United States)

    Bian, He-Dong; Yang, Xiao-E.; Yu, Qing; Chen, Zi-Lu; Liang, Hong; Yan, Shi-Ping; Liao, Dai-Zheng

    2008-01-01

    Two helical coordination polymeric copper(II) complexes bearing amino acid Schiff bases HL or HL', which are condensed from 2-hydroxy-1-naphthaldehyde with 2-aminobenzoic acid or L-valine, respectively, have been prepared and characterised by X-ray crystallography. In [CuL] n ( 1) the copper(II) atoms are bridged by syn- anti carboxylate groups giving infinite 1-D right-handed helical chains which are further connected by weak C-H⋯Cu interactions to build a 2-D network. While in [CuL'] n ( 2) the carboxylate group acts as a rare monatomic bridge to connect the adjacent copper(II) atoms leading to the formation of a left-handed helical chain. Magnetic susceptibility measurements indicate that 1 exhibits weak ferromagnetic interactions whereas an antiferromagnetic coupling is established for 2. The magnetic behavior can be satisfactorily explained on the basis of the structural data.

  4. Synthesis and magnetic properties of bulk transparent PMMA/Fe-oxide nanocomposites

    Science.gov (United States)

    Li, Shanghua; Qin, Jian; Fornara, Andrea; Toprak, Muhammet; Muhammed, Mamoun; Kim, Do Kyung

    2009-05-01

    PMMA/Fe-oxide nanocomposites are fabricated by a chemical method. Monodispersed Fe-oxide nanoparticles are well dispersed in the PMMA matrix by in situ polymerization, resulting in a bulk transparent polymeric nanocomposite. The magnetic behavior of the PMMA/Fe-oxide nanocomposites is investigated. The transparent PMMA/Fe-oxide nanocomposite has potentially interesting magneto-optic applications without compromising the advantages of a lightweight, noncorrosive polymeric material with very high transparency even for bulk samples.

  5. Synthesis and magnetic properties of bulk transparent PMMA/Fe-oxide nanocomposites

    International Nuclear Information System (INIS)

    Li Shanghua; Qin Jian; Fornara, Andrea; Toprak, Muhammet; Muhammed, Mamoun; Kim, Do Kyung

    2009-01-01

    PMMA/Fe-oxide nanocomposites are fabricated by a chemical method. Monodispersed Fe-oxide nanoparticles are well dispersed in the PMMA matrix by in situ polymerization, resulting in a bulk transparent polymeric nanocomposite. The magnetic behavior of the PMMA/Fe-oxide nanocomposites is investigated. The transparent PMMA/Fe-oxide nanocomposite has potentially interesting magneto-optic applications without compromising the advantages of a lightweight, noncorrosive polymeric material with very high transparency even for bulk samples.

  6. Influence of synthesis approach on structural and magnetic properties of lithium ferrite nanoparticles

    International Nuclear Information System (INIS)

    Dar, M. Abdullah; Shah, Jyoti; Siddiqui, W.A.; Kotnala, R.K.

    2012-01-01

    Highlights: ► Nanocrystalline Li 0.5 Fe 2.5 O 4 ferrites were synthesized with an average crystallite size of 12.3 nm and 5.7 nm by chemical co-precipitation and reverse microemulsion technique respectively. ► The non-saturated M–H loops, absence of hysteresis, remanence and coercivity at room temperature is indicative of the presence of superparamagnetic and single-domain particles for both the materials. ► The blocking temperature T B shifts to lower temperature with the increase of applied field, which is attributed to the reduction of magnetocrystalline anisotropy constant. ► At high temperature, microemulsion synthesized nanoparticles are observed to show a maxima immediately below the Curie temperature which is attributed to the cumulative effect of the anisotropy variation of temperature and particle size growth during the measurement. - Abstract: Nanocrystalline Li 0.5 Fe 2.5 O 4 ferrite particles were synthesized with an average crystallite size of 12.3 nm and 5.7 nm by chemical coprecipitation and reverse microemulsion technique respectively. Zero-field cooled (ZFC) and field cooled (FC) magnetization measurements at different magnetic fields and magnetic hysteresis loops at different temperatures have been measured. The non-saturation of M–H loops with a very low coercivity and remenance at room temperature confirms the presence of superparamagnetic (SPM) nature and single-domain ferrite particles. The blocking temperature (T B ) has been found to shift towards the lower temperature region with the increase in applied magnetic field. It has been attributed to the reduction of magnetocrystalline anisotropy constant and blocking temperature dereases from 145 K to 110 K with increase in field from 50 Oe to 1000 Oe in the samples synthesized by microemulsion method. At high temperature, microemulsion synthesized nanoparticles show a maximum in magnetization versus temperature plot just below the Curie temperature (T C ) which has been attributed

  7. Low temperature synthesis, magnetic and electrical properties of iron-magnesium superparamagnetic nanoalloy

    Energy Technology Data Exchange (ETDEWEB)

    Nazir, Rabia [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Mazhar, Muhammad [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan)], E-mail: mazhar42pk@yahoo.com; Akhtar, Muhammad Javed; Nadeem, Muhammad; Siddique, Muhammad [Physics Division, Pinstech, P.O. Nilore, Islamabad (Pakistan); Shah, Raza [HEJ Research Institute of Chemistry, University of Karachi, Karachi 75270 (Pakistan); Hasanain, S. Khurshid [Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

    2009-06-24

    A low temperature chemical approach which beats the miscibility barrier of Fe and Mg has been designed to synthesize Fe-Mg{sub 2} nanoalloy and tested to result nanoparticles of average 30 nm size. The nanoalloy is amorphous in nature and characterized by XPRD, AFM, magnetometery, Moessbauer and impedance spectroscopies. The result of magnetic measurement suggests the sample to be superparamagnetic as evidenced by the {sup 57}Fe Moessbauer spectroscopy. The two Mg atoms occupy different positions around iron resulting in two phase system as shown by Moessbauer and impedance spectroscopies.

  8. Low temperature synthesis, magnetic and electrical properties of iron-magnesium superparamagnetic nanoalloy

    International Nuclear Information System (INIS)

    Nazir, Rabia; Mazhar, Muhammad; Akhtar, Muhammad Javed; Nadeem, Muhammad; Siddique, Muhammad; Shah, Raza; Hasanain, S. Khurshid

    2009-01-01

    A low temperature chemical approach which beats the miscibility barrier of Fe and Mg has been designed to synthesize Fe-Mg 2 nanoalloy and tested to result nanoparticles of average 30 nm size. The nanoalloy is amorphous in nature and characterized by XPRD, AFM, magnetometery, Moessbauer and impedance spectroscopies. The result of magnetic measurement suggests the sample to be superparamagnetic as evidenced by the 57 Fe Moessbauer spectroscopy. The two Mg atoms occupy different positions around iron resulting in two phase system as shown by Moessbauer and impedance spectroscopies.

  9. Synthesis and magnetic Properties of dinuclear oxovanadium(IV) complexes bridged by tetracarboxylato groups

    International Nuclear Information System (INIS)

    Li, Y.-T.; Guan, H.-S.; Yan, C.-W.

    2004-01-01

    Three novel μ-tetracarboxylato-bridged oxovanadium(IV) complexes described by the overall formula [(VO) 2 (PMTA)L 2 ] where PMTA stands for the tetraanion of pyromellitic acid, and L denotes 2,2'-bipyridine(bpy), 4,4'-dimethyl-2,2'-bipyridine (Me 2 bpy) or 1,10-phenanthroline (phen), respectively, have been synthesized and characterized by elemental analyses, molar conductivity and room-temperature magnetic moment measurements, IR, ESR, and electronic spectral studies. It is proposed that these complexes have PMTA-bridged structures and consist of two oxovanadium(IV) ions, each in the square-pyramidal environment. The [(VO) 2 (PMTA)(bpy) 2 ] (1) and [(VO) 2 (PMTA)(phen) 2 ] (2) complexes were further characterized by variable temperature (4.2 - 300 K) magnetic susceptibility measurements and the observed data were fitted to the modified Bleaney-Bowers equation by the least-squares, giving the exchange integral J = -2.75 cm -1 for (1) and J -3.91 cm -1 for (2). This results indicates that there is a weak antiferromagnetic spin-exchange interaction between the two VO 2+ ions within each molecule. (author)

  10. A copper-based layered coordination polymer: synthesis, magnetic properties and electrochemical performance in supercapacitors.

    Science.gov (United States)

    Liu, Qi; Liu, Xiuxiu; Shi, Changdong; Zhang, Yanpeng; Feng, Xuejun; Cheng, Mei-Ling; Su, Seng; Gu, Jiande

    2015-11-28

    A copper-based layered coordination polymer ([Cu(hmt)(tfbdc)(H2O)]; hmt = hexamethylenetetramine, tfbdc = 2,3,5,6-tetrafluoroterephthalate; Cu-LCP) has been synthesized, and it has been structurally and magnetically characterized. The Cu-LCP shows ferromagnetic interactions between the adjacent copper(II) ions. Density functional theory calculations on the special model of Cu-LCP support the occurrence of ferromagnetic interactions. As an electrode material for supercapacitors, Cu-LCP exhibits a high specific capacitance of 1274 F g(-1) at a current density of 1 A g(-1) in 1 M LiOH electrolyte, and the capacitance retention is about 88% after 2000 cycles.

  11. Sonochemical synthesis, structure and magnetic properties of air-stable Fe3O4/Au nanoparticles

    International Nuclear Information System (INIS)

    Wu Wei; He Quanguo; Chen Hong; Tang Jianxin; Nie Libo

    2007-01-01

    Air-stable nanoparticles of Fe 3 O 4 /Au were prepared via sonolysis of a solution mixture of hydrogen tetrachloroaureate(III) trihydrate (HAuCl 4 ) and (3-aminopropyl)triethoxysilane (APTES)-coated Fe 3 O 4 nanoparticles with further drop-addition of sodium citrate. The Fe 3 O 4 /Au nanoparticles were characterized by x-ray powder diffraction (XRD), ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS) and superconducting quantum interference device (SQUID) magnetometry. Nanoparticles of Fe 3 O 4 /Au obtained under appropriate conditions possess a very high saturation magnetization of about 63 emu g -1 and their average diameter is about 30 nm

  12. Low temperature synthesis, photoluminescence, magnetic properties of the transition metal doped wurtzite ZnS nanowires

    International Nuclear Information System (INIS)

    Cao, Jian; Han, Donglai; Wang, Bingji; Fan, Lin; Fu, Hao; Wei, Maobin; Feng, Bo; Liu, Xiaoyan; Yang, Jinghai

    2013-01-01

    In this paper, we synthesized the transition metal ions (Mn, Cu, Fe) doped and co-doped ZnS nanowires (NWs) by a one-step hydrothermal method. The results showed that the solid solubility of the Fe 2+ ions in the ZnS NWs was about two times larger than that of the Mn 2+ or Cu 2+ ions in the ZnS NWs. There was no phase transformation from hexagonal to cubic even in a large quantity transition metal ions introduced for all the samples. The Mn 2+ /Cu 2+ /Fe 2+ related emission peaks can be observed in the Mn 2+ ,Cu 2+ and Fe 2+ doped ZnS NWs. The ferromagnetic properties of the co-doped samples were investigated at room temperature. - graphical abstract: The stable wurtzite ZnS:TM 2+ (TM=Mn, Cu, Fe) nanowires with room temperature ferromagnetism properties were obtained. The different elongation of unit cell caused by the different doped ions was observed. Highlights: ► The transition metal ions doped wurtzite ZnS nanowires were synthesized at 180 °C. ► There was no phase transformation from hexagonal to cubic even in a large quantity introduced for all the samples. ► The room temperature ferromagnetism properties of the co-doped nanowires were investigated

  13. Synthesis, characterization and properties

    Indian Academy of Sciences (India)

    Unknown

    work, we report herein the synthesis, structural cha- racterization and properties of a chiral Mn(IV) mononuclear ... atmosphere with a platinum disc working electrode, a platinum wire auxiliary electrode and a Ag/AgCl ... SMART APEX CCD area detector system [λ(Mo-. Kα) = 0⋅71073 Å], graphite monochromator, 2400.

  14. Ferrites nanoparticles MFe2O4 (M = Ni and Zn: hydrothermal synthesis and magnetic properties

    Directory of Open Access Journals (Sweden)

    Pérez Mazariego, J. L.

    2008-06-01

    Full Text Available MFe2O4 (M = Ni and Zn nanoparticles were prepared by the hydrothermal method. The obtained samples were characterized by X-ray and electron diffraction, Scanning and Transmission Electron Microscopy and Mössbauer spectroscopy. The transmission images show homogeneous shape and particle size ranging from 10 to 40 nm, depending on the nature of the M cation. Mössbauer spectroscopy yields to a ratio of occupancy between the A and B sites of 0.7 in the case of NiFe2O4 oxide. DC magnetization (2-300 K measurements reveal a superparamagnetic behaviour for the ZnFe2O4 sample with a blocking temperature of 20 K. By contrast, in the case of the NiFe2O4 ferrite the blocking temperature appears to be above 300 K and at lower temperature, it shows a ferrimagnetic behaviour arising from the superexchange interactions that take place in this inverse spinel. Mössbauer spectroscopy results confirm the bulk magnetic measurements.Se han preparado mediante el método hidrotermal nanopartículas de ferritas MFe2O4 (M = Ni, Zn. Las muestras obtenidas fueron caracterizadas mediante difracción de rayos X y electrones, microscopía electrónica de transmisión y barrido y espectroscopia Mössbauer. Las imágenes de transmisión muestran partículas de forma y tamaño homogéneo de 10 a 40 nm según la naturaleza del catión M. La espectroscopia Mössbauer revela una relación de ocupación entre los sitios A y B por los átomos de hierro de 0.7 en el caso del óxido NiFe2O4. Las medidas de magnetización DC (2 – 300 K muestran un comportamiento superparamagnético para la muestra ZnFe2O4 con una temperatura de bloqueo de 20 K. En el caso de las nanopartículas de NiFe2O4 la temperatura de bloqueo parece estar por encima de los 300 K mostrando por debajo de la misma, comportamiento ferrimagnético provocado por las interacciones de superintercambio que tienen lugar en esta espinela inversa. Los resultados de espectroscopia Mössbauer confirman los datos de las

  15. 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.

  16. Effect of Synthesis Temperature on Structure and Magnetic Properties of (La,Nd)0.7Sr0.3MnO3 Nanoparticles.

    Science.gov (United States)

    Shlapa, Yulia; Solopan, Sergii; Bodnaruk, Andrii; Kulyk, Mykola; Kalita, Viktor; Tykhonenko-Polishchuk, Yulia; Tovstolytkin, Alexandr; Belous, Anatolii

    2017-12-01

    Two sets of Nd-doped La 0.7 Sr 0.3 MnO 3 nanoparticles were synthesized via sol-gel method with further heat treatment at 1073 and 1573 K, respectively. Crystallographic and magnetic properties of obtained nanoparticles were studied, and the effect of synthesis conditions on these properties was investigated. According to X-ray data, all particles crystallized in the distorted perovskite structure. Magnetic parameters, such as saturation magnetization, coercivity, Curie temperature, and specific loss power, which is released on the exposure of an ensemble of nanoparticles to AC magnetic field, were determined for both sets of samples. The correlation between the values of Curie temperature and maximal heating temperature under AC magnetic field was found. It was revealed that for the samples synthesized at 1573 K, the dependences of crystallographic and magnetic parameters on Nd content were monotonous, while for the samples synthesized at 1073 K, they were non-monotonous. It was concluded that Nd-doped La 0.7 Sr 0.3 MnO 3 nanoparticles are promising materials for self-controlled magnetic hyperthermia applications, but the researchers should be aware of the unusual behavior of the particles synthesized at relatively low temperatures.

  17. Synthesis and magnetic properties of CoFe2O4 spinel ferrite nanoparticles doped with lanthanide ions

    International Nuclear Information System (INIS)

    Kahn, Myrtil L.; Zhang, Z. John

    2001-01-01

    Lanthanide ions have been doped into cobalt spinel ferrites using an oil-in-water micellar method to form CoLn 0.12 Fe 1.88 O 4 nanoparticles with Ln=Ce, Sm, Eu, Gd, Dy, or Er. Doping with lanthanide ions (Ln III ) modulates the magnetic properties of cobalt spinel ferrite nanoparticles. In particular cases of Gd 3+ or Dy 3+ ions, a dramatic increase in the blocking temperature and coercivity is observed. Indeed, the introduction of only 4% of Gd 3+ ions increases the blocking temperature ∼100 K and the coercivity 60%. Initial studies on the magnetic properties of these doped nanoparticles clearly demonstrate that the relationship between the modulation of magnetic properties and the nature of doped Ln III ions is interesting but very complex. [copyright] 2001 American Institute of Physics

  18. Polystyrene/magnetite nanocomposite synthesis and characterization: investigation of magnetic and electrical properties for using as microelectromechanical systems (MEMS

    Directory of Open Access Journals (Sweden)

    Omidi Mohammad Hassan

    2017-02-01

    Full Text Available In this work, a novel polystyrene/Fe3O4 nanocomposite prepared by in-situ method is presented. Magnetic Fe3O4 nanoparticles were encapsulated by polystyrene. The FT-IR spectra confirmed polystyrene/Fe3O4 nanocomposite preparation. The electrical properties of prepared nanocomposite were investigated by cyclic voltammetry (CV. The CV analysis showed good electrical conductivity of the synthesized nanocomposite. Magnetic properties of the nanocomposite were studied by vibrating sample magnetometer (VSM. The VSM analysis confirmed magnetic properties of the nanocomposite. The morphology and the size of the synthesized nanocomposite were investigated by field emission scanning electron microscope (FESEM. According to the VSM and CV results, such nanocomposite can be used in microelectromechanical systems.

  19. 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.

  20. CoFe2O4 nanocrystalline powders prepared by citrate-gel methods: Synthesis, structure and magnetic properties

    International Nuclear Information System (INIS)

    Cannas, C.; Falqui, A.; Musinu, A.; Peddis, D.; Piccaluga, G.

    2006-01-01

    Nanocrystalline CoFe 2 O 4 powders were prepared by decomposition of metal ion citrate precursors. Four samples were synthesized from precursor solutions having different pH values in the range 2 physisorption and Transmission Electron Microscopy. Magnetic properties were explored by a SQUID magnetometer. Three out of the four samples, coming from solutions of pH 2, 4 and 7, were produced by an autocombustion reaction and are very similar as regards average size of the nanoparticles (about 20 nm), their morphology and the magnetic properties, while the fourth sample was produced by a slower thermal decomposition and is composed of smaller nanoparticles (about 10 nm)

  1. Synthesis of Fe Ni Alloy Nano materials by Proteic Sol-Gel Method: Crystallographic, Morphological, and Magnetic Properties

    International Nuclear Information System (INIS)

    Santos, C.M.D.; Martins, A.F.N.; Sasaki, J.M.; Costa, B. C.; Ribeiro, T.S.; Braga, T.P.; Soares, J.M.

    2016-01-01

    Proteic Sol-Gel method was used for the synthesis of Fe Ni alloy at different temperature conditions and flow reduction. The solids were characterized by XRD, H_2-TPR, SEM, TEM, Moessbauer spectroscopy, and VSM. It was observed by X-ray diffraction pure Fe Ni alloy in the samples reduced at 600 degree (40 ml/min H_2 flow) and 700 degree (25 ml/min H_2 flow). The Fe Ni alloy presented stability against the oxidizing atmosphere up to 250 degree. The morphology exhibited agglomerates relatively spherical and particles in the range of 10-40 nm. Moessbauer spectroscopy showed the presence of disordered ferromagnetic Fe Ni alloy, and magnetic hysteresis loop revealed a typical behavior of soft magnetic material.

  2. Iron(iii) bis(pyrazol-1-yl)acetate based decanuclear metallacycles: synthesis, structure, magnetic properties and DFT calculations.

    Science.gov (United States)

    Gajewska, Małgorzata J; Bieńko, Alina; Herchel, Radovan; Haukka, Matti; Jerzykiewicz, Maria; Ożarowski, Andrzej; Drabent, Krzysztof; Hung, Chen-Hsiung

    2016-09-27

    The synthesis, structural aspects, magnetic interpretation and theoretical rationalizations for a new member of the ferric wheel family, a decanuclear iron(iii) complex with the formula [Fe 10 (bdtbpza) 10 (μ 2 -OCH 3 ) 20 ] (1), featuring the N,N,O tridentate bis(3,5-di-tert-butylpyrazol-1-yl)acetate ligand, are reported. The influence of the steric effect on both the core geometry and coordination mode is observed. Temperature dependent (2.0-300 K range) magnetic susceptibility studies carried out on complexes 1 established unequivocally antiferromagnetic (AF) interactions between high-spin iron(iii) centers (S = 5/2), leading to a ground state S = 0. The mechanism of AF intramolecular coupling was proved using a broken-symmetry approach within the density functional method at the B3LYP/def2-TZVP(-f)/def2-SVP level of theory.

  3. Synthesis of FeNi Alloy Nanomaterials by Proteic Sol-Gel Method: Crystallographic, Morphological, and Magnetic Properties

    Directory of Open Access Journals (Sweden)

    Cássio Morilla dos Santos

    2016-01-01

    Full Text Available Proteic Sol-Gel method was used for the synthesis of FeNi alloy at different temperature conditions and flow reduction. The solids were characterized by XRD, H2-TPR, SEM, TEM, Mössbauer spectroscopy, and VSM. It was observed by X-ray diffraction pure FeNi alloy in the samples reduced at 600°C (40 mL/min H2 flow and 700°C (25 mL/min H2 flow. The FeNi alloy presented stability against the oxidizing atmosphere up to 250°C. The morphology exhibited agglomerates relatively spherical and particles in the range of 10–40 nm. Mössbauer spectroscopy showed the presence of disordered ferromagnetic FeNi alloy, and magnetic hysteresis loop revealed a typical behavior of soft magnetic material.

  4. Structure and magnetic properties of Co and Ni nano-ferrites prepared by a two step direct microemulsions synthesis

    Czech Academy of Sciences Publication Activity Database

    Pulišová, Petra; Kováč, J.; Voigt, A.; Raschman, P.

    2013-01-01

    Roč. 341, september (2013), s. 93-99 ISSN 0304-8853 Institutional support: RVO:61388980 Keywords : Precipitation in microemulsion s * Ferrite nano-powder * Magnetic properties * ZFC * FC measurements Subject RIV: CA - Inorganic Chemistry Impact factor: 2.002, year: 2013

  5. Synthesis, structure and magnetic properties of distorted Y{sub x}La{sub 1-x}FeO{sub 3}: Effects of mechanochemical activation and composition

    Energy Technology Data Exchange (ETDEWEB)

    Cristobal, A.A. [Instituto de Investigaciones en Ciencia y Tecnologia de Materiales, INTEMA (CONICET-UNMdP), J.B. Justo 4302 B7608FDQ, Mar del Plata (Argentina); Botta, P.M., E-mail: pbotta@fi.mdp.edu.ar [Instituto de Investigaciones en Ciencia y Tecnologia de Materiales, INTEMA (CONICET-UNMdP), J.B. Justo 4302 B7608FDQ, Mar del Plata (Argentina); Aglietti, E.F.; Conconi, M.S. [Centro de Tecnologia de Recursos Minerales y Ceramica, CETMIC (CIC-CONICET), Camino P. Centenario y 506 B1897ZCA, Gonnet (Argentina); Bercoff, P.G. [Facultad de Matematica, Astronomia y Fisica, FaMAF UNC and IFEG (CONICET), Ciudad Universitaria (5000), Cordoba (Argentina); Porto Lopez, J.M. [Instituto de Investigaciones en Ciencia y Tecnologia de Materiales, INTEMA (CONICET-UNMdP), J.B. Justo 4302 B7608FDQ, Mar del Plata (Argentina)

    2011-11-01

    Highlights: {yields} Y{sub x}La{sub 1-x}FeO{sub 3} phases (0 {<=} x {<=} 1) were prepared at RT by mechanochemical treatment. {yields} The obtained materials showed an anisotropic distortion of its crystal structure. {yields} Combination of Y-doping and mechanochemistry produced weak ferromagnetic materials. {yields} Thermal treatments improved the structural order, leading to antiferromagnetic solids. {yields} Neel temperature decreased with x due to less stable magnetic structures. - Abstract: The influence of mechanochemical treatment on the synthesis and properties of Y{sub x}La{sub 1-x}FeO{sub 3} (0 {<=} x {<=} 1) orthoferrites is studied. Solid mixtures of the corresponding metal oxides were treated in a high-energy ball-mill. X-ray diffraction revealed that during the milling the disappearance of the reactants and a fast conversion to orthoferrite phase take place. Magnetic measurements showed a weak ferromagnetic behavior of the obtained materials, observing higher magnetization for larger x. The activated powders heated at 600 and 800 deg. C showed a progressive crystalline ordering together with a significant drop of magnetization. Thermal treatments at 1000 deg. C produced the formation of the phase Y{sub 3}Fe{sub 5}O{sub 12} for the samples richer in yttrium, increasing the magnetization. Rietveld refinements of the diffraction patterns and dynamical scanning calorimetry were used respectively to determine the lattice parameters and Neel temperatures for the formed orthoferrites. The effect of the composition on the structure and magnetic behavior is discussed.

  6. Synthesis, nanostructure and magnetic properties of FeCo-reduced graphene oxide composite films by one-step electrodeposition

    International Nuclear Information System (INIS)

    Cao, Derang; Li, Hao; Wang, Zhenkun; Wei, Jinwu; Wang, Jianbo; Liu, Qingfang

    2015-01-01

    FeCo-reduced graphene oxide (FeCo-RGO) composite film was fabricated on indium tin oxide substrate using one-step electrodeposition method. Raman spectroscopy and field emission scanning electron microscope results show that the reduced graphene oxide is coprecipitated with the FeCo film. The energy-dispersive spectrometer results demonstrate that the atomic ratio of Fe/Co in FeCo-RGO composite film is larger than that of the FeCo film under the same fabrication condition. As a result, the FeCo-RGO composite film exhibits good soft magnetic properties and high-frequency properties as well as the FeCo film. The magnetic anisotropy field and saturation magnetization of FeCo-RGO composite film are increased when compared with FeCo film. Furthermore, the ferromagnetic resonance frequency is improved from 2.15 GHz for the FeCo film to 3.9 GHz for the FeCo-RGO composite film. - Highlights: • FeCo-reduced graphene oxide composite film was fabricated on indium tin oxide substrate. • One step electrodeposition method was used. • Good soft magnetic properties were exhibited by the composite films. • Increase of resonance frequency from 2.15 GHz for FeCo film to 3.9 GHz for composite film

  7. 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

  8. 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.

  9. Synthesis and anomalous magnetic properties of LaFeO{sub 3} nanoparticles by hot soap method

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Tatsuo, E-mail: tfujii@cc.okayama-u.ac.jp [Department of Applied Chemistry, Okayama University, Tsushima-naka 3-1-1, Okayama 700-8530 (Japan); Matsusue, Ikkoh; Nakatsuka, Daisuke; Nakanishi, Makoto; Takada, Jun [Department of Applied Chemistry, Okayama University, Tsushima-naka 3-1-1, Okayama 700-8530 (Japan)

    2011-10-03

    Highlights: {yields} Nanocrystalline LaFeO{sub 3} particles were synthesized by using hot soap technique. {yields} Average diameter of the obtained LaFeO{sub 3} nanoparticles was about 15 nm. {yields} They exhibited superparamagnetic behavior with a blocking temperature of 30 K. {yields} Large magnetization due to the presence of uncompensated surface spins was induced. - Abstract: Nanocrystalline LaFeO{sub 3} particles were synthesized at low temperatures by using hot soap technique. The synthesis was based on the thermal decomposition of organometallic compounds precipitated in a hot coordinating solvent. Moderate heat treatment at low temperature far below the combustion point of organic compounds produced spherical LaFeO{sub 3} nanoparticles with average diameter of about 15 nm. The crystalline phase, structure and particle size of obtained products were characterized by X-ray diffraction, infrared spectroscopy and transmission electron microscopy observations. In spite of the antiferromagnetic nature of bulk LaFeO{sub 3}, the obtained nanoparticles exhibited anomalous large magnetization. Superparamagnetic behavior with a blocking temperature of about 30 K was observed in both magnetization and Moessbauer spectroscopic analyses.

  10. Hydrothermal synthesis of HoMn{sub 2}O{sub 5} nanorods and their size-dependent magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Yichao; Wu, Songping, E-mail: chwsp@scut.edu.cn; Xu, Rui

    2017-03-01

    The HoMn{sub 2}O{sub 5} nanorods were synthesized by a surfactant-assisted hydrothermal process. The length of nanorods is readily controllable with basically constant diameter. HoMn{sub 2}O{sub 5} nanorods show recognizable divagation at T{sub N}(Ho) of 13 K between FC and ZFC curve due to the contribution of the magnetic ordering of holmium. Size-dependent magnetic properties (i.e. a critical length for magnetization) of HoMn{sub 2}O{sub 5} nanorods can be ascribed to the competition between surface strain and uncompensated spin at the surface. - Highlights: • HoMn{sub 2}O{sub 5} nanorods were synthesized by a surfactant-assisted hydrothermal route. • HoMn{sub 2}O{sub 5} nanorods show recognizable divagation at T{sub N}(Ho) of 13 K between FC and ZFC. • Size-dependent magnetic properties of HoMn{sub 2}O{sub 5} nanorods can be observed.

  11. Synthesis, structure and magnetic properties of crystallographically aligned CuCr{sub 2}Se{sub 4} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Esters, Marco [Department of Chemistry, University of Oregon, Eugene, OR 97403 (United States); Liebig, Andreas [Institut für Physik, Universität Augsburg, 86159 Augsburg (Germany); Ditto, Jeffrey J.; Falmbigl, Matthias [Department of Chemistry, University of Oregon, Eugene, OR 97403 (United States); Albrecht, Manfred [Institut für Physik, Universität Augsburg, 86159 Augsburg (Germany); Johnson, David C., E-mail: davej@uoregon.edu [Department of Chemistry, University of Oregon, Eugene, OR 97403 (United States)

    2016-06-25

    We report the low temperature synthesis of highly textured CuCr{sub 2}Se{sub 4} thin films using the modulated elemental reactant (MER) method. The structure of CuCr{sub 2}Se{sub 4} is determined for the first time in its thin film form and exhibits cell parameters that are smaller than found in bulk CuCr{sub 2}Se{sub 4}. X-ray diffraction and precession electron diffraction show a strong degree of crystallographic alignment of the crystallites, where the <111> axis is oriented perpendicular to the substrate surface, while being rotationally disordered within the plane. Temperature and field dependent in-plane and out-of-plane magnetization measurements show that the film is ferromagnetic with a Curie temperature of 406 K CuCr{sub 2}Se{sub 4} synthesized utilizing the MER method shows stronger magnetic anisotropy (effective anisotropy: 1.82 × 10{sup 6} erg cm{sup −3}; shape anisotropy: 1.07 × 10{sup 6} erg cm{sup −3}), with the easy axis lying out of plane, and a larger magnetic moment (6 μ{sub B}/f.u.) than bulk CuCr{sub 2}Se{sub 4}. - Highlights: • Crystallographically aligned, phase pure CuCr{sub 2}Se{sub 4} were synthesized. • The degree of alignment decreases with annealing time. • The films are ferromagnetic with the easy axis along the <111> direction. • The magnetization is larger than bulk CuCr{sub 2}Se{sub 4} or other CuCr{sub 2}Se{sub 4} films made to date.

  12. Synthesis and Magnetic Properties of Nearly Monodisperse CoFe2O4Nanoparticles Through a Simple Hydrothermal Condition

    Directory of Open Access Journals (Sweden)

    Li Xing-Hua

    2010-01-01

    Full Text Available Abstract Nearly monodisperse cobalt ferrite (CoFe2O4 nanoparticles without any size-selection process have been prepared through an alluring method in an oleylamine/ethanol/water system. Well-defined nanospheres with an average size of 5.5 nm have been synthesized using metal chloride as the law materials and oleic amine as the capping agent, through a general liquid–solid-solution (LSS process. Magnetic measurement indicates that the particles exhibit a very high coercivity at 10 K and perform superparamagnetism at room temperature which is further illuminated by ZFC/FC curves. These superparamagnetic cobalt ferrite nanomaterials are considered to have potential application in the fields of biomedicine. The synthesis method is possible to be a general approach for the preparation of other pure binary and ternary compounds.

  13. Hydrothermal synthesis, crystal structure, luminescent and magnetic properties of a new mononuclear GdIII coordination complex

    Science.gov (United States)

    Coban, Mustafa Burak

    2018-06-01

    A new GdIII coordination complex, {[Gd(2-stp)2(H2O)6].2(4,4'-bipy).4(H2O)}, complex 1, (2-stp = 2-sulfoterephthalate anion and 4,4'-bipy = 4,4'-bipyridine), has been synthesized by hydrothermal method and characterized by elemental analysis, solid state UV-Vis and FT-IR spectroscopy, single-crystal X-ray diffraction, solid state photoluminescence and variable-temperature magnetic measurements. The crystal structure determination shows that GdIII ions are eight coordinated and adopt a distorted square-antiprismatic geometry. Molecules interacting through intra- and intermolecular (O-H⋯O, O-H⋯N) hydrogen bonds in complex 1, give rise to 3D hydrogen bonded structure and the discrete lattice 4,4'-bipy molecules occupy the channel of the 3D structure. π-π stacking interactions also exist 4,4'-bipy-4,4'-bipy and 4,4'-bipy-2-stp molecule rings in 3D structures. Additionally, solid state photoluminescence properties of complex 1 at room temperature have been investigated. Under the excitation of UV light (at 349 nm), the complex 1 exhibited green emissions (at 505 nm) of GdIII ion in the visible region. Furthermore, Variable-temperature magnetic susceptibility and isothermal magnetization as function of external magnetic field studies reveal that complex 1 displays possible antiferromagnetic interaction.

  14. 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.

  15. Microemulsion synthesis and magnetic properties of hydroxyapatite-encapsulated nano CoFe{sub 2}O{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Foroughi, Firoozeh [Department of Materials Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Isfahan (Iran, Islamic Republic of); Hassanzadeh-Tabrizi, S.A., E-mail: tabrizi1980@gmail.com [Young Researchers and Elite Club, Najafabad Branch, Islamic Azad University, Najafabad, Isfahan (Iran, Islamic Republic of); Amighian, Jamshid [Department of Materials Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Isfahan (Iran, Islamic Republic of)

    2015-05-15

    Hydroxyapatite-encapsulated cobalt ferrite (CoFe{sub 2}O{sub 4}) nanopowders were synthesized by one step microemulsion method. The powders were characterized by X-ray Diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometer. TEM results showed that nanoparticles calcined at 700 °C have core–shell morphology. It was found that the resultant phases, morphology and magnetic properties of the samples depend on calcining temperature. The synthesized nanoparticles showed a maximum saturation magnetization of 7.8 emu/g with a wasp-waisted hysteresis loop. The magnetion was reduced by increasing calcining temperature to 900 °C. This reduction is due to the reaction of cobalt ferrite with hydroxyapatite which leads to CaFe{sub 12}(PO{sub 4}){sub 8}(OH){sub 12} phase. - Highlights: • Hydroxyapatite-encapsulated cobalt ferrite nanopowders were synthesized by a microemulsion method. • The characterization of nanoparticles was performed using various analytical tools, such as TEM, FE-SEM, FTIR, XRD and VSM. • The nanoparticles showed a maximum saturation magnetization of 7.8 emu/g. • The samples indicated a wasp-waisted hysteresis loop.

  16. Aloe vera plant-extracted solution hydrothermal synthesis and magnetic properties of magnetite (Fe3O4) nanoparticles

    Science.gov (United States)

    Phumying, Santi; Labuayai, Sarawuth; Thomas, Chunpen; Amornkitbamrung, Vittaya; Swatsitang, Ekaphan; Maensiri, Santi

    2013-06-01

    Magnetite (Fe3O4) nanoparticles have been successfully synthesized by a novel hydrothermal method using ferric acetylacetonate (Fe(C5H8O2)3) and aloe vera plant-extracted solution. The influences of different reaction temperatures and times on the structure and magnetic properties of the synthesized Fe3O4 nanoparticles were investigated. The synthesized nanoparticles are crystalline and have particle sizes of ˜6-30 nm, as revealed by transmission electron microscopy (TEM). The results of X-ray diffraction (XRD), High resolution TEM (HRTEM) and selected area electron diffraction (SAED) indicate that the synthesized Fe3O4 nanoparticles have the inverse cubic spinel structure without the presence of any other phase impurities. The hysteresis loops of the Fe3O4 nanoparticles at room temperature show superparamagnetic behavior and the saturation magnetization of the Fe3O4 samples increases with increasing reaction temperature and time.

  17. Synthesis and magnetic properties of PrFe11V1-xTix and their nitrides

    International Nuclear Information System (INIS)

    Tang, S.L.; Wang, B.W.; Zhang, C.; Jin, X.M.; Zhang, S.Y.; Du, Y.W.

    1997-01-01

    We have succeeded in synthesizing PrFe 11 V 1-x Ti x (x=0.2 1) compound and their nitrides with the ThMn 12 -type structure. The phase formation and magnetic properties have been investigated by x-ray diffraction, differential thermometric analysis, and magnetic measurement. The stable temperature range of the 1-12 phase for PrFe 11 V 1-x Ti x alloys has been determined as a function of Ti content. PrFe 11 V compounds with the ThMn 12 -type structure do not exist and PrFe 11 Ti compounds with the TnMn 12 -type structure are obtained by annealing in a narrow temperature range between 1303 and 1383 K. Furthermore, 1-12 phase with the ThMn 12 -type structure can be obtained at lower temperature and wider temperature range with decreasing Ti content x (0.2≤x≤1). PrFe 11 V 1-x Ti x N y with x=0.2 1 has a T c of about 730 785 K, B a larger than 8 T and M s in the range 144 148 emu/g. These intrinsic magnetic properties are highly favorable for permanent magnet applications. As a preliminary, an intrinsic coercivity of 5.4 kOe is obtained for PrFe 11 V 0.5 Ti 0.5 N y at room temperature by using mechanical alloying technique. copyright 1997 American Institute of Physics

  18. Jingle-bell-shaped ferrite hollow sphere with a noble metal core: Simple synthesis and their magnetic and antibacterial properties

    International Nuclear Information System (INIS)

    Li Siheng; Wang Enbo; Tian Chungui; Mao Baodong; Kang Zhenhui; Li Qiuyu; Sun Guoying

    2008-01-01

    In this paper, a simple strategy is developed for rational fabrication of a class of jingle-bell-shaped hollow structured nanomaterials marked as Ag(MFe 2 O 4 ) (M=Ni, Co, Mg, Zn), consisting of ferrite hollow shells and metal nanoparticle cores, using highly uniform colloidal Ag(C) microspheres as template. The final composites were obtained by direct adsorption of metal cations Fe 3+ and M 2+ on the surface of the Ag(C) spheres followed by calcination process to remove the middle carbon shell and transform the metal ions into pure phase ferrites. The as-prepared composites were characterized by X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray analysis (EDX), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis spectroscopy and SQUID magnetometer. The results showed that the composites possess the magnetic property of the ferrite shell and the optical together with antibacterial property of the Ag core. - Graphical abstract: MFe 2 O 4 (M=Ni, Co, Mg, Zn) hollow spheres with a noble metal nanoparticle core were successfully prepared by using colloidal metal(C) core-shell spheres as templates with no need of surface modification. The shell thickness and magnetic properties of the ferrite hollow spheres could be controlled by varying the synthetic parameters

  19. Controllable synthesis, crystal structure and magnetic properties of Monomer-Dimer Cocrystallized MnIII Salen-type composite material

    Science.gov (United States)

    Wu, Qiong; Wu, Wei; Wu, Yongmei; Li, Weili; Qiao, Yongfeng; Wang, Ying; Wang, Baoling

    2018-04-01

    By the reaction of manganese-Schiff-base complexes with penta-anionic Anderson heteropolyanion, a new supramolecular architecture [Mn2(Salen)2(H2O)2][Mn(Salen)(H2O)2]2Na[IMo6O24]·8H2O (1) (salen = N,N‧-ethylene-bis (salicylideneiminate) has been isolated. Compound 1 was characterized by the single-crystal X-ray diffraction, elemental, IR and thermal gravimetric analyses. Structural analysis reveals that the unit cell simultaneously contains MnIII-Salen dimer and monomer cation fragments, for which the Anderson-type polyanions serve as counter anions. In the packing arrangement, all the MnIII dimers are well separated by polyoxometalate units and form tertiary structure together with MnIII monomers. Interestingly, different from the previous work, in the exact same reaction conditions, we are able to template MnIII-Salen complexes into different configurations by varying the charge state of polyanions. Besides, the magnetic properties of 1 were also examined by using both dc and ac magnetic field of the superconducting quantum interference devices. Most importantly, our fitting of the experimental data to a Heisenberg-type spin model shows that there exists a ferromagnetic exchange interaction ∼5 K between the spins (S = 2) on MnIII in the dimer, while antiferromagnetic ones exist among monomers and dimer (∼2 K). This meta-magnetic state could induce a slight spin frustration at low temperature, which would in turn affect the magnetic behavior. In addition, our ac field measurement of the susceptibilities suggests a typical signature for a single-molecule magnet.

  20. Metal-organic coordination architectures of tetrazole heterocycle ligands bearing acetate groups: Synthesis, characterization and magnetic properties

    Science.gov (United States)

    Hu, Bo-Wen; Zheng, Xiang-Yu; Ding, Cheng

    2015-12-01

    Two new coordination complexes with tetrazole heterocycle ligands bearing acetate groups, [Co(L)2]n (1) and [Co3(L)4(N3)2·2MeOH]n (2) (L=tetrazole-1-acetate) have been synthesized and structurally characterized. Single crystal structure analysis shows that the cobalt-complex 1 has the 3D 3,6-connected (42.6)2(44.62.88.10)-ant topology. By introducing azide in this system, complex 2 forms the 2D network containing the [Co3] units. And the magnetic properties of 1 and 2 have been studied.

  1. A novel asymmetric chair-like hydroxyl-bridged tetra-copper compound: Synthesis, supramolecular structure and magnetic property

    Science.gov (United States)

    Wang, Xiao-Feng; Du, Ke-Jie; Wang, Hong-Qing; Zhang, Xue-Li; Nie, Chang-Ming

    2017-06-01

    A new polynuclear Cu(II) compound, [Cu4(bpy)4(OH)4(H2O)(BTC)]NO3·8H2O (1), was prepared by self-assembly from the solution of copper(II) nitrate and two kinds of ligands, 2,2‧-bipyridine (bpy) and benzene-tricarboxylic acid (H3BTC). Single crystal structure analysis reveals that 1 features a rare asymmetric chair-like hydroxyl-bridged tetra-copper cluster: [Cu4(OH)4] core along with one H2O and one BTC3- occupied each terminal coordinated site. In addition, the magnetic property has been investigated.

  2. Modifications in the rhombohedral degree of distortion and magnetic properties of Ba-doped BiFeO3 as a function of synthesis methodology

    International Nuclear Information System (INIS)

    Rojas-George, G.; Silva, J.; Castañeda, R.; Lardizábal, D.; Graeve, O.A.; Fuentes, L.; Reyes-Rojas, A.

    2014-01-01

    We present an analysis of crystallographic symmetry and the origin of the pseudo-cubic character of doped BiFeO 3 . Specifically, barium-doped bismuth ferrite, Bi 1−x Ba x FeO 3 (x = 0.05, 0.075, 0.1, 0.125), perovskite-type nanoparticles have been synthesized by implementing five modifications to the sol–gel technique (citric acid-assisted sol–gel method, ethylene glycol method, tartaric acid-assisted sol–gel method, polyvinyl alcohol–ethylene glycol method, and EDTA complexing sol–gel method) and their final pseudo-cubic character is discussed. The effect of the carboxylic groups and hydroxyl groups during synthesis is critical to obtain single phase BBFO. Fourier transform infrared spectroscopy and thermogravimetric analysis is used to study the decomposition and thermal behavior of the precursors and their relation to the final nanoparticle characteristics. X-ray diffraction analysis shows a single phase with symmetry changes for four of the five synthesis methodologies employed. Only the EDTA complexing sol–gel method, where EDTA is used as dissolver and chelating agent, is not satisfactory in all concentration ranges. Rietveld results suggest that the degree of distortion of the rhombohedral symmetry in the crystallized BiFeO 3 powders decreases 12% as a result of progressive substitution of Bi 3+ by Ba 2+ and that there is no shift from rhombohedral to tetragonal symmetry. Magnetization properties of samples with a low-distortion rhombohedral structure show higher magnetic saturation and remanent magnetization than samples with high-distortion rhombohedral structure. - Highlights: • Ba–BiFeO 3 : rhombohedral distortion degree is highly affected by the chemical method. • Rietveld results show no shift in BBFO from rhombohedral to tetragonal symmetry. • The low-distortion rhombohedral structure show higher magnetic saturation. • To stabilize a metal complex is necessary a balance between COOH − and OH − groups

  3. MAGNETIC WOVEN FABRICS - PHYSICAL AND MAGNETIC PROPERTIES

    Directory of Open Access Journals (Sweden)

    GROSU Marian C

    2015-05-01

    Full Text Available A coated material is a composite structure that consists of at least two components: base material and coating layer. The purpose of coating is to provide special properties to base material, with potential to be applied in EMI shielding and diverse smart technical fields. This paper reports the results of a study about some physical and magnetic properties of coated woven fabrics made from cotton yarns with fineness of 17 metric count. For this aim, a plain woven fabric was coated with a solution hard magnetic polymer based. As hard magnetic powder, barium hexaferrite (BaFe12O19 was selected. The plain woven fabric used as base has been coated with five solutions having different amounts of hard magnetic powder (15% - 45% in order to obtain five different magnetic woven fabrics. A comparison of physical properties regarding weight (g/m2, thickness (mm, degree of charging (% and magnetic properties of magnetic woven samples were presented. Saturation magnetizing (emu/g, residual magnetizing (emu/g and coercive force (kA/m of pure hard magnetic powder and woven fabrics have been studied as hysteresis characteristics. The magnetic properties of the woven fabrics depend on the mass percentage of magnetic powder from coating solution. Also, the residual magnetism and coercive field of woven fabrics represents only a part of bulk barium hexafferite residual magnetism and coercive field.

  4. Synthesis of ferrofluids based on cobalt ferrite nanoparticles: Influence of reaction time on structural, morphological and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Amirabadizadeh, Ahmad; Salighe, Zohre; Sarhaddi, Reza, E-mail: reza.sarhaddi@birjand.ac.ir; Lotfollahi, Zahra

    2017-07-15

    Highlights: • Ferrofluids based on cobalt ferrite nanoparticles were synthesized by co-precipitation method. • The crystallite and particle size of cobalt ferrite can be controlled effectively by reaction time. • The ferrofluids have lower values of saturation magnetization and coercivity as compared to nanoparticles. • By increasing the size of nanoparticles, the narrower and sharper spikes of ferrofluids are formed. - Abstract: In this work, for first time the ferrofluids based on the cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles were prepared by the co-precipitation method at different reaction times (0.5–6.5 h). Crystal structure, morphology and magnetic properties of the cobalt ferrite nanoparticles and the ferrofluids based on the nanoparticles were studied by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and vibrating sample magnetometer (VSM). The XRD patterns of CoFe{sub 2}O{sub 4} nanoparticles synthesized at different reaction times indicated that all samples are single phase in accordance with inverse cubic spinel structure with space group Fd-3m, and no impurity phase was observed. By increasing the reaction time to 3.5 h, the lattice parameter and the average crystallites size increased and then afterwards decreased by increasing the reaction time. The microscopic studies indicated the formation of nanosized particles with nearly spherical in shape, whereas the average particle size for all samples is found to be less than 50 nm. The results of VSM also showed that the saturation magnetization and coercivity field of the cobalt ferrite nanoparticles and the ferrofluids were influenced by reaction time, whereas the ferrofluids have lower values of magnetic parameters than that of nanoparticles.

  5. Magnetic nanoparticles based nano-composites: synthesis, contribution of the fillers dispersion and the chains conformation on the reinforcement properties

    International Nuclear Information System (INIS)

    Robbes, Anne-Sophie

    2011-01-01

    The mechanical properties of polymeric nano-composite films can be considerably enhanced by the inclusion of inorganic nanoparticles due to two main effects: (i) the local structure of fillers dispersion and (ii) the potential modification of the chains conformation and dynamics in the vicinity of the filler/polymer interface. However, the precise mechanisms which permit to correlate these contributions at nano-metric scale to the macroscopic mechanical properties of the materials are actually poorly described. In such a context, we have synthesized model nano-composites based on magnetic nanoparticles of maghemite γ-Fe 2 O 3 (naked or grafted with a polystyrene (PS) corona by radical controlled polymerization) dispersed in a PS matrix, that we have characterized by combining small angle scattering (X-Ray and neutron) and transmission electronic microscopy. By playing on different parameters such as the particle size, the concentration, or the size ratio between the grafted chains and the ones of the matrix in the case of the grafted fillers, we have obtained nano-composite films a large panel of controlled and reproducible controlled filler structures, going from individual nanoparticles or fractal aggregates up to the formation of a connected network of fillers. By applying an external magnetic field during the film processing, we succeeded in aligning the different structures along the direction of the field and we obtained materials with remarkable anisotropic reinforcement properties. The conformation of the chains of the matrix, experimentally determined thanks to the specific properties of neutron contrast of the system, is not affected by the presence of the fillers, whatever their confinement, the dispersion the fillers or their chemical state surface. The alignment of the fillers along the magnetic field has allowed us to describe precisely the evolution of the reinforcement modulus of the materials with the structural reorganization of the fillers and

  6. Synthesis, structure and magnetic properties of La{sub 3}Co{sub 2}SbO{sub 9}: A double perovskite with competing antiferromagnetic and ferromagnetic interactions

    Energy Technology Data Exchange (ETDEWEB)

    Franco, D.G.; Fuertes, V.C.; Blanco, M.C. [INFIQC (CONICET), Departamento de Fisicoquimica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba, Ciudad Universitaria, X5000HUA Cordoba (Argentina); Fernandez-Diaz, M.T. [Institute Laue-Langevin (ILL) 156X, F-38042 Grenoble Cedex 9 (France); Sanchez, R.D., E-mail: rodo@cab.cnea.gov.ar [Centro Atomico Bariloche, CNEA and Instituto Balseiro, Universidad Nacional de Cuyo, Av. Bustillo 9500, 8400 Rio Negro (Argentina); Carbonio, R.E., E-mail: carbonio@fcq.unc.edu.ar [INFIQC (CONICET), Departamento de Fisicoquimica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba, Ciudad Universitaria, X5000HUA Cordoba (Argentina)

    2012-10-15

    The synthesis, structural characterization, and magnetic properties of La{sub 3}Co{sub 2}SbO{sub 9} double perovskite are reported. The crystal structure has been refined by X-ray and neutron powder diffraction data in the monoclinic space group P2{sub 1}/n. Co{sup 2+} and Sb{sup 5+} have the maximum order allowed for the La{sub 3}Co{sub 2}SbO{sub 9} stoichiometry. Rietveld refinements of powder neutron diffraction data show that at room temperature the cell parameters are a=5.6274(2) A, b=5.6842(2) A, c=7.9748(2) A and {beta}=89.999(3) Degree-Sign . Magnetization measurements indicate the presence of ferromagnetic correlations with T{sub C}=55 K attributed to the exchange interactions for non-linear Co{sup 2+}-O-Sb{sup 5+}-O-Co{sup 2+} paths. The effective magnetic moment obtained experimentally is {mu}{sub exp}=4.38 {mu}{sub B} (per mol Co{sup 2+}), between the theoretical one for spin only (3.87 {mu}{sub B}) and spin-orbit value (6.63 {mu}{sub B}), indicating partially unquenched contribution. The low magnetization value at high magnetic field and low temperature (1 {mu}{sub B}/f.u., 5 T and 5 K) and the difference between ZFC and FC magnetization curves (at 5 kOe) indicate that the ferromagnetism do not reach a long range order and that the material has an important magnetic frustration. - Graphical abstract: Co-O-Co (Yellow octahedra only) rich zones (antiferromagnetic) are in contact with Co-O-Sb-O-Co (Red and yellow octahedra) rich zones (Ferromagnetic) to give the peculiar magnetic properties, as a consequence, a complex hysteresis loop can be observed composed by a main and irreversible curve in all the measured range, superimposed with a ferromagnetic component at low fields. Highlights: Black-Right-Pointing-Pointer La{sub 3}Co{sub 2}SbO{sub 9} has small Goldschmidt Tolerance Factor (t) due to the small size of La{sup 3+}. Black-Right-Pointing-Pointer Small t determines an angle for the path Co{sup 2+}-O-Sb{sup 5+}-O-Co{sup 2+} of 153 Degree-Sign . Black

  7. Synthesis, structure and magnetic properties of La3Co2SbO9: A double perovskite with competing antiferromagnetic and ferromagnetic interactions

    International Nuclear Information System (INIS)

    Franco, D.G.; Fuertes, V.C.; Blanco, M.C.; Fernández-Díaz, M.T.; Sánchez, R.D.; Carbonio, R.E.

    2012-01-01

    The synthesis, structural characterization, and magnetic properties of La 3 Co 2 SbO 9 double perovskite are reported. The crystal structure has been refined by X-ray and neutron powder diffraction data in the monoclinic space group P2 1 /n. Co 2+ and Sb 5+ have the maximum order allowed for the La 3 Co 2 SbO 9 stoichiometry. Rietveld refinements of powder neutron diffraction data show that at room temperature the cell parameters are a=5.6274(2) Å, b=5.6842(2) Å, c=7.9748(2) Å and β=89.999(3)°. Magnetization measurements indicate the presence of ferromagnetic correlations with T C =55 K attributed to the exchange interactions for non-linear Co 2+ –O–Sb 5+ –O–Co 2+ paths. The effective magnetic moment obtained experimentally is μ exp =4.38 μ B (per mol Co 2+ ), between the theoretical one for spin only (3.87 μ B ) and spin-orbit value (6.63 μ B ), indicating partially unquenched contribution. The low magnetization value at high magnetic field and low temperature (1 μ B /f.u., 5 T and 5 K) and the difference between ZFC and FC magnetization curves (at 5 kOe) indicate that the ferromagnetism do not reach a long range order and that the material has an important magnetic frustration. - Graphical abstract: Co–O–Co (Yellow octahedra only) rich zones (antiferromagnetic) are in contact with Co–O–Sb–O–Co (Red and yellow octahedra) rich zones (Ferromagnetic) to give the peculiar magnetic properties, as a consequence, a complex hysteresis loop can be observed composed by a main and irreversible curve in all the measured range, superimposed with a ferromagnetic component at low fields. Highlights: ► La 3 Co 2 SbO 9 has small Goldschmidt Tolerance Factor (t) due to the small size of La 3+ . ► Small t determines an angle for the path Co 2+ –O–Sb 5+ –O–Co 2+ of 153°. ► Ferromagnetism is attributed to exchange interactions for Co 2+ –O–Sb 5+ –O–Co 2+ paths. ► Ferromagnetic nanoclusters are embedded in an antiferromagnetic

  8. Poly(o-phenylenediamine)/NiCoFe2O4 nanocomposites: Synthesis, characterization, magnetic and dielectric properties

    Science.gov (United States)

    Kannapiran, Nagarajan; Muthusamy, Athianna; Chitra, Palanisamy; Anand, Siddeswaran; Jayaprakash, Rajan

    2017-02-01

    In this study, poly(o-phenylenediamine) (PoPD)/NiCoFe2O4 nanocomposites were synthesized by in-situ oxidative chemical polymerization method with different amount of NiCoFe2O4 nanoparticles. The NiCoFe2O4 nanoparticles were prepared by auto-combustion method. The structural, morphological, thermal properties of the synthesized PoPD/NiCoFe2O4 nanocomposites were characterized by fourier transform infrared spectrum (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Magnetic properties of NiCoFe2O4 nanoparticles and PoPD/NiCoFe2O4 nanocomposites were studied by vibrating sample magnetometer (VSM). The FTIR and XRD techniques were used to confirm the formation of PoPD/NiCoFe2O4 nanocomposites. The average crystalline size of NiCoFe2O4 nanoparticles and PoPD/NiCoFe2O4 nanocomposites were calculated from XRD. From the SEM analysis, spherical morphology of the PoPD was confirmed. The TGA results showed that the NiCoFe2O4 nanoparticles have improved the thermal stability of PoPD. Dielectric properties of PoPD/NiCoFe2O4 nanocomposites at different temperatures have been carried in the frequency range 50 Hz to 5 MHz.

  9. Core@shell@shell structured carbon-based magnetic ternary nanohybrids: Synthesis and their enhanced microwave absorption properties

    Science.gov (United States)

    Yang, Erqi; Qi, Xiaosi; Xie, Ren; Bai, Zhongchen; Jiang, Yang; Qin, Shuijie; Zhong, Wei; Du, Youwei

    2018-05-01

    High encapsulation efficiency of core@shell@shell structured carbon-based magnetic ternary nanohybrids have been synthesized in high yield by chemical vapor deposition of acetylene directly over octahedral-shaped Fe2O3 nanoparticles. By controlling the pyrolysis temperature, Fe3O4@Fe3C@carbon nanotubes (CNTs) and Fe@Fe3C@CNTs ternary nanohybrids could be selectively produced. The optimal RL values for the as-prepared ternary nanohybrids could reach up to ca. -46.7, -52.7 and -29.5 dB, respectively. The excellent microwave absorption properties of the obtaiend ternary nanohybrids were proved to ascribe to the quarter-wavelength matching model. Moreover, the as-prepared Fe@Fe3C@CNTs ternary nanohybrids displayed remarkably enhanced EM wave absorption capabilities compared to Fe3O4@Fe3C@CNTs due to their excellent dielectric loss abilities, good complementarities between the dielectric loss and the magnetic loss, and high attenuation constant. Generally, this strategy can be extended to explore other categories of core@shell or core@shell@shell structured carbon-based nanohybrids, which is very beneficial to accelerate the advancements of high performance MAMs.

  10. Controllable synthesis, magnetic and biocompatible properties of Fe3O4 and α-Fe2O3 nanocrystals

    International Nuclear Information System (INIS)

    Zhou, Xi; Shi, Yanfeng; Ren, Lei; Bao, Shixiong; Han, Yu; Wu, Shichao; Zhang, Honggang; Zhong, Lubin; Zhang, Qiqing

    2012-01-01

    Iron oxide nanocrystals (NCs) with a series of well-controlled morphologies (octahedron, rod, wire, cube and plate) and compositions (Fe 3 O 4 and α-Fe 2 O 3 ) were synthesized via a facile hydrothermal process. The morphological and compositional control of various iron oxide NCs was based on the regulations of precursor thermolysis kinetics and surfactants. The obtained samples were characterized by XRD, SEM, TEM, SQUID and cytotoxicity test. These as-prepared iron oxide NCs showed excellent magnetic properties and good biocompatibility, paving the way for their high-efficiency bio-separation and bio-detection applications. - Graphical Abstract: Schematic illustration for the formation of iron oxide NCs (Fe 3 O 4 and α-Fe 2 O 3 ) with different controlled morphologies and compositions. Highlights: ► Iron oxide NCs with a series of well-controlled morphologies (octahedron, rod, wire, cube, and plate) and compositions (Fe 3 O 4 and α-Fe 2 O 3 ) were synthesized via a facile hydrothermal method. ► The mechanism of the morphological and compositional control process is directly related to precursor thermolysis kinetics and surfactants. ► These iron oxide NCs exhibited excellent magnetic response and good biocompatibility, which should have great applications in the cell separation and biodetection.

  11. Effects of size reduction on the structure and magnetic properties of core-shell Ni3Si/silica nanoparticles prepared by electrochemical synthesis

    Czech Academy of Sciences Publication Activity Database

    Pigozzi, G.; Mukherji, D.; Elerman, Y.; Strunz, Pavel; Gilles, R.; Hoelzel, M.; Barbier, B.; Schmutz, P.

    2014-01-01

    Roč. 584, JAN (2014), s. 119-127 ISSN 0925-8388 Institutional support: RVO:61389005 Keywords : intermetallics * nanostructured materials * transition metal alloys and compounds * electrochemical synthesis * crystal structure * magnetic measurements Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.999, year: 2014

  12. Solvothermal synthesis and good microwave absorbing properties for magnetic porous-Fe3O4/graphene nanocomposites

    Directory of Open Access Journals (Sweden)

    Xiaojun Zeng

    2017-05-01

    Full Text Available The magnetic porous-Fe3O4/graphene nanocomposites have been fabricated by a facile solvothermal method. The porous Fe3O4 nanospheres are embedded uniformly in the graphene oxide (GO sheets to form a 3D Fe3O4/GO nanocomposite network. The dielectric properties for the Fe3O4/GO composites can be greatly improved by the 7 wt% GO additions. Good impedance matching can be also obtained in these Fe3O4/GO composites, which is proved to dominate their excellent microwave absorbing properties including the minimum reflection loss (RL value of -43.7 dB at 6.8 GHz with a sample thickness of 5 mm and a broad absorption bandwidth of 5.92 GHz (below -10 dB. These porous-Fe3O4/GO composites also exhibit the good structural stability and low density, which shows their great potential application in high-performance electromagnetic microwave-absorbing materials.

  13. A series of novel lanthanide carboxyphosphonates with a 3D framework structure: synthesis, structure, and luminescent and magnetic properties.

    Science.gov (United States)

    Chen, Kai; Dong, Da-Peng; Sun, Zhen-Gang; Jiao, Cheng-Qi; Li, Chao; Wang, Cheng-Lin; Zhu, Yan-Yu; Zhao, Yan; Zhu, Jiang; Sun, Shou-Hui; Zheng, Ming-Jing; Tian, Hui; Chu, Wei

    2012-08-28

    By introduction of 1,4-benzenedicarboxylic acid as the second organic ligand, a series of novel lanthanide carboxyphosphonates with a 3D framework structure, namely, [Ln(3)(H(2)L)(HL)(2)(bdc)(2)(H(2)O)]·7H(2)O (Ln = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8); H(3)L = H(2)O(3)PCH(2)NC(5)H(9)COOH; H(2)bdc = HOOCC(6)H(4)COOH) have been synthesized under hydrothermal conditions. Compounds are isostructural and feature a 3D framework in which Ln(III) polyhedra are interconnected by bridging {CPO(3)} tetrahedra into 2D inorganic layers parallel to the ab plane. The organic groups of H(2)L(-) are grafted on the two sides of the layer. These layers are further cross-linked by the bdc(2-) ligands from one layer to the Ln atoms from the other into a pillared-layered architecture with one-dimensional channel system along the a axis. The thermal stability of compounds has been investigated. Luminescent properties of compounds , and the magnetic properties of compound have also been studied.

  14. Jingle-bell-shaped ferrite hollow sphere with a noble metal core: Simple synthesis and their magnetic and antibacterial properties

    Science.gov (United States)

    Li, Siheng; Wang, Enbo; Tian, Chungui; Mao, Baodong; Kang, Zhenhui; Li, Qiuyu; Sun, Guoying

    2008-07-01

    In this paper, a simple strategy is developed for rational fabrication of a class of jingle-bell-shaped hollow structured nanomaterials marked as Ag@ MFe 2O 4 ( M=Ni, Co, Mg, Zn), consisting of ferrite hollow shells and metal nanoparticle cores, using highly uniform colloidal Ag@C microspheres as template. The final composites were obtained by direct adsorption of metal cations Fe 3+ and M 2+ on the surface of the Ag@C spheres followed by calcination process to remove the middle carbon shell and transform the metal ions into pure phase ferrites. The as-prepared composites were characterized by X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray analysis (EDX), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis spectroscopy and SQUID magnetometer. The results showed that the composites possess the magnetic property of the ferrite shell and the optical together with antibacterial property of the Ag core.

  15. Polyfuran Conducting Polymers: Synthesis, Properties, and Applications.

    OpenAIRE

    González-Tejera, M.J.; Sánchez de la Blanca, Emilia; Carrillo Ramiro, Isabel

    2008-01-01

    In this review, polyfuran (PFu) synthesis methods and the nucleation mechanism; the electrochemical, structural, morphological, and magnetic properties of PFu; thermal behavior; theoretical calculations on PFu, as well as its applications reported to date, have been compiled. Not only PFu homopolymers have been reviewed, but also PFu co-polymers, PFu bipolymers, and PFu composites. The results are listed, discussed, and compared. It is hoped that this assembly of all the relevant data might e...

  16. Synthesis and characterization of functional magnetic nanocomposites

    Science.gov (United States)

    Gass, J.; Sanders, J.; Srinath, S.; Srikanth, H.

    2006-03-01

    Magnetic nanoparticles and carbon nanotubes have been excellent functional materials that could be dispersed in polymer matrices for various applications. However, uniform dispersion of particles in polymers without agglomeration is quite challenging. We have fabricated PMMA/polypyrrole bilayer structures embedded with Fe3O4 magnetite nanoparticles synthesized using wet chemical synthesis. Agglomeration-free dispersion of nanoparticles was achieved by coating the particles with surfactants and by dissolving both the particles and PMMA in chlorobenzene. Structural characterization was done using XRD and TEM. Magnetic properties of the bilayer structures indicated superparamagnetic behavior that is desirable for RF applications as the magnetic losses are reduced. Our polymer nanocomposite bilayer films with conducting polymer coatings are potential candidates for tunable RF applications with integrated EMI suppression. We will also report on our studies of pumped ferrofluids flowing past carbon nanotubes that are arranged in microchannel arrays. Magnetization under various flow conditions is investigated and correlated with the hydrodynamic properties. This scheme provides a novel method of energy conversion and storage using nanocomposite materials.

  17. Liquid-phase synthesis of nickel nanoparticles stabilized by PVP and study of their structural and magnetic properties

    Czech Academy of Sciences Publication Activity Database

    Singh, M.; Kumar, M.; Štěpánek, F.; Ulbrich, P.; Svoboda, P.; Šantavá, Eva; Singla, M.L.

    2011-01-01

    Roč. 2, č. 6 (2011), s. 409-414 ISSN 0976-3961 Institutional research plan: CEZ:AV0Z10100520 Keywords : nanoparticles * magnetic materials * electron microscopy * superparamagnetism Subject RIV: BM - Solid Matter Physics ; Magnetism

  18. Electronic, electrical and magnetic ceramics synthesis and characterization

    International Nuclear Information System (INIS)

    Calix, V.S.; Saligan, P.P.; Naval, P.C.

    1989-01-01

    This paper describes the research and development activities of the Philippine Nuclear Research Institute (PNRI) on the synthesis and characterization of soft and hard ferrites and some beta alumina type superionic conductor materials. XRD, XRF and Moessbauer effect spectrometry are used to determine the structure phases, compositions and some magnetic properties of the materials. Effects of composition and preparation methods on the bulk electronic and magnetic properties are also discussed. (Auth.). 6 figs.; 3 tabs

  19. Dinuclear Cu(II) complexes of isomeric bis-(3-acetylacetonate)benzene ligands: synthesis, structure, and magnetic properties.

    Science.gov (United States)

    Rancan, Marzio; Dolmella, Alessandro; Seraglia, Roberta; Orlandi, Simonetta; Quici, Silvio; Sorace, Lorenzo; Gatteschi, Dante; Armelao, Lidia

    2012-05-07

    Highly versatile coordinating ligands are designed and synthesized with two β-diketonate groups linked at the carbon 3 through a phenyl ring. The rigid aromatic spacer is introduced in the molecules to orient the two acetylacetone units along different angles and coordination vectors. The resulting para, meta, and ortho bis-(3-acetylacetonate)benzene ligands show efficient chelating properties toward Cu(II) ions. In the presence of 2,2'-bipyridine, they promptly react and yield three dimers, 1, 2, and 3, with the bis-acetylacetonate unit in bridging position between two metal centers. X-ray single crystal diffraction shows that the compounds form supramolecular chains in the solid state because of intermolecular interactions. Each of the dinuclear complexes shows a magnetic behavior which is determined by the combination of structural parameters and spin polarization effects. Notably, the para derivative (1) displays a moderate antiferromagnetic coupling (J = -3.3 cm(-1)) along a remarkably long Cu···Cu distance (12.30 Å).

  20. Modifications in the rhombohedral degree of distortion and magnetic properties of Ba-doped BiFeO{sub 3} as a function of synthesis methodology

    Energy Technology Data Exchange (ETDEWEB)

    Rojas-George, G. [Centro de Investigación en Materiales Avanzados S.C., Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua, Chih. 31109 (Mexico); Silva, J. [Universidad Autónoma de Ciudad Juárez, Ave. del Charro 450 Norte, Cd. Juárez, Chih. 32310 (Mexico); Castañeda, R.; Lardizábal, D. [Centro de Investigación en Materiales Avanzados S.C., Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua, Chih. 31109 (Mexico); Graeve, O.A. [Department of Mechanical and Aerospace Engineering, University of California, San Diego, 9500 Gilman Dr. – MC 0411, La Jolla, CA 92093-0411 (United States); Fuentes, L. [Centro de Investigación en Materiales Avanzados S.C., Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua, Chih. 31109 (Mexico); Reyes-Rojas, A., E-mail: armando.reyes@cimav.edu.mx [Centro de Investigación en Materiales Avanzados S.C., Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua, Chih. 31109 (Mexico)

    2014-07-01

    We present an analysis of crystallographic symmetry and the origin of the pseudo-cubic character of doped BiFeO{sub 3}. Specifically, barium-doped bismuth ferrite, Bi{sub 1−x}Ba{sub x}FeO{sub 3} (x = 0.05, 0.075, 0.1, 0.125), perovskite-type nanoparticles have been synthesized by implementing five modifications to the sol–gel technique (citric acid-assisted sol–gel method, ethylene glycol method, tartaric acid-assisted sol–gel method, polyvinyl alcohol–ethylene glycol method, and EDTA complexing sol–gel method) and their final pseudo-cubic character is discussed. The effect of the carboxylic groups and hydroxyl groups during synthesis is critical to obtain single phase BBFO. Fourier transform infrared spectroscopy and thermogravimetric analysis is used to study the decomposition and thermal behavior of the precursors and their relation to the final nanoparticle characteristics. X-ray diffraction analysis shows a single phase with symmetry changes for four of the five synthesis methodologies employed. Only the EDTA complexing sol–gel method, where EDTA is used as dissolver and chelating agent, is not satisfactory in all concentration ranges. Rietveld results suggest that the degree of distortion of the rhombohedral symmetry in the crystallized BiFeO{sub 3} powders decreases 12% as a result of progressive substitution of Bi{sup 3+} by Ba{sup 2+} and that there is no shift from rhombohedral to tetragonal symmetry. Magnetization properties of samples with a low-distortion rhombohedral structure show higher magnetic saturation and remanent magnetization than samples with high-distortion rhombohedral structure. - Highlights: • Ba–BiFeO{sub 3}: rhombohedral distortion degree is highly affected by the chemical method. • Rietveld results show no shift in BBFO from rhombohedral to tetragonal symmetry. • The low-distortion rhombohedral structure show higher magnetic saturation. • To stabilize a metal complex is necessary a balance between COOH{sup

  1. Magnetically frustrated double perovskites: synthesis, structural properties, and magnetic order of Sr{sub 2}BOsO{sub 6} (B = Y, In, Sc)

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Avijit Kumar; Sarapulova, Angelina; Adler, Peter; Kanungo, Sudipta; Mikhailova, Daria; Schnelle, Walter; Hu, Zhiwei; Kuo, Changyang; Yan, Binghai; Felser, Claudia; Tjeng, Liu Hao [Max-Planck-Institut fuer Chemische Physik fester Stoffe,Dresden (Germany); Reehuis, Manfred [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Berlin (Germany); Siruguri, Vasudeva; Rayaprol, Sudhindra [UGC-DAE Consortium for Scientific Research (CSR), Mumbai Centre, Mumbai (India); Soo, Yunlian [Department of Physics, National Tsing Hua University, Hsinchu (China); Jansen, Martin [Max-Planck-Institut fuer Chemische Physik fester Stoffe,Dresden (Germany); Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany)

    2015-02-15

    Double perovskites Sr{sub 2}BOsO{sub 6} (B = Y, In, and Sc) were prepared from the respective binary metal oxides, and their structural, magnetic, and electronic properties were investigated. At room temperature all these compounds crystallize in the monoclinic space group P2{sub 1}/n. They contain magnetic osmium (Os{sup 5+}, t{sub 2g}{sup 3}) ions and are antiferromagnetic insulators with Neel temperatures T{sub N} = 53 K, 26 K, and 92 K for B = Y, In, and Sc, respectively. Powder neutron diffraction studies on Sr{sub 2}YOsO{sub 6} and Sr{sub 2}InOsO{sub 6} showed that the crystal structures remain unchanged down to 3 K. The Y and In compounds feature a type I antiferromagnetic spin structure with ordered Os moments of 1.91 μ{sub B} and 1.77 μ{sub B}, respectively. The trend in T{sub N} does not simply follow the development of the lattice parameters, which suggests that d{sup 0} compared to d{sup 10} ions on the B site favor a somewhat different balance of exchange interactions in the frustrated Os{sup 5+} fcc-like lattice. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Synthesis and characterization of anisotropic magnetic hydrogels

    Energy Technology Data Exchange (ETDEWEB)

    Hinrichs, Stephan, E-mail: stephan.hinrichs@chemie.uni-hamburg.de; Nun, Nils; Fischer, Birgit, E-mail: birgit.fischer@chemie.uni-hamburg.de

    2017-06-01

    Multiresponsive hydrogels are an interesting new class of materials. They offer the advantage, that they respond to different stimuli like temperature, pH and magnetic fields. By this they can change their properties which makes the hydrogels ideal candidates for many applications in the technical as well as medical field. Here we present the synthesis and characterization of hydrogels - micro- as well as macrogels - which consist of an iron oxide core, varying in phase and morphology, embedded in a thermoresponsive polymer, consisting of poly N-isopropylacrylamide. By using dynamic light scattering we investigated the thermoresponsive properties. In addition we were able to follow the formation of the macrogel by monitoring the shear viscosity.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-04-15

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

  4. Room-temperature synthesis of three-dimensional porous ZnO@CuNi hybrid magnetic layers with photoluminescent and photocatalytic properties

    Science.gov (United States)

    Guerrero, Miguel; Zhang, Jin; Altube, Ainhoa; García-Lecina, Eva; Roldan, Mònica; Baró, Maria Dolors; Pellicer, Eva; Sort, Jordi

    2016-01-01

    Abstract A facile synthetic approach to prepare porous ZnO@CuNi hybrid films is presented. Initially, magnetic CuNi porous layers (consisting of phase separated CuNi alloys) are successfully grown by electrodeposition at different current densities using H2 bubbles as a dynamic template to generate the porosity. The porous CuNi alloys serve as parent scaffolds to be subsequently filled with a solution containing ZnO nanoparticles previously synthesized by sol-gel. The dispersed nanoparticles are deposited dropwise onto the CuNi frameworks and the solvent is left to evaporate while the nanoparticles impregnate the interior of the pores, rendering ZnO-coated CuNi 3D porous structures. No thermal annealing is required to obtain the porous films. The synthesized hybrid porous layers exhibit an interesting combination of tunable ferromagnetic and photoluminescent properties. In addition, the aqueous photocatalytic activity of the composite is studied under UV−visible light irradiation for the degradation of Rhodamine B. The proposed method represents a fast and inexpensive approach towards the implementation of devices based on metal-semiconductor porous systems, avoiding the use of post-synthesis heat treatment steps which could cause deleterious oxidation of the metallic counterpart, as well as collapse of the porous structure and loss of the ferromagnetic properties. PMID:27877868

  5. Effect of surfactant for magnetic properties of iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Haracz, S. [Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614 Poznań (Poland); Hilgendorff, M. [Freie Universität Berlin, Fachbereich Physik, Arnimalle 14, 14195 Berlin (Germany); Rybka, J.D. [Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614 Poznań (Poland); Giersig, M. [Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614 Poznań (Poland); Freie Universität Berlin, Fachbereich Physik, Arnimalle 14, 14195 Berlin (Germany)

    2015-12-01

    Highlights: • Dynamic behavior of magnetic nanoparticles. • Synthesis of iron oxide nanoparticles. • Effect of surfactant for magnetic properties. - Abstract: For different medical applications nanoparticles (NPs) with well-defined magnetic properties have to be used. Coating ligand can change the magnetic moment on the surface of nanostructures and therefore the magnetic behavior of the system. Here we investigated magnetic NPs in a size of 13 nm conjugated with four different kinds of surfactants. The surface anisotropy and the magnetic moment of the system were changed due to the presence of the surfactant on the surface of iron oxide NPs.

  6. Template synthesis and magnetic properties of highly aligned barium hexaferrite (BaFe12O19) nanofibers

    International Nuclear Information System (INIS)

    Huang, Boneng; Li, Congju; Wang, Jiaona

    2013-01-01

    Using electrospun poly(ethylene terephthalate)/citric acid (PET/CA) microfibers as the template, highly aligned barium hexaferrite (BaFe 12 O 19 ) nanofibers with diameters of ca. 800 nm and lengths up to 2 cm were synthesized by sol–gel precursor coating technique and subsequent high temperature calcination. Structural and morphological investigations revealed that individual BaFe 12 O 19 nanofibers were composed of numerous nanocrystallites stacking alternatively along the nanofiber axis, the average grain size was ca. 225 nm and the single crystallites on each BaFe 12 O 19 nanofibers were of random orientations. The formation mechanism of aligned BaFe 12 O 19 nanofibers was proposed based on experiment. The magnetic measurement revealed that the aligned BaFe 12 O 19 nanofibers exhibited orientation-dependent magnetic behavior with respect to the applied magnetic field. The magnetic anisotropy with the easy magnetizing axis along the length of the nanofibers was due to the shape anisotropy. Such aligned magnetic nanofibers can find relevance in application requiring an orientation-dependent physical response. - Highlights: ► A simple method was used to synthesize the aligned BaFe 12 O 19 nanofibers. ► The aligned BaFe 12 O 19 nanofibers display an obvious orientation-dependent magnetic behavior. ► The method can be readily applied to other aligned one-dimensional inorganic nanomaterials

  7. Synthesis of magnetic systems producing field with maximal scalar characteristics

    International Nuclear Information System (INIS)

    Klevets, Nickolay I.

    2005-01-01

    A method of synthesis of the magnetic systems (MSs) consisting of uniformly magnetized blocks is proposed. This method allows to synthesize MSs providing maximum value of any magnetic field scalar characteristic. In particular, it is possible to synthesize the MSs providing the maximum of a field projection on a given vector, a gradient of a field modulus and a gradient of a field energy on a given directing vector, a field magnitude, a magnetic flux through a given surface, a scalar product of a field or a force by a directing function given in some area of space, etc. The synthesized MSs provide maximal efficiency of permanent magnets utilization. The usage of the proposed method of MSs synthesis allows to change a procedure of projecting in principal, namely, to execute it according to the following scheme: (a) to choose the sizes, a form and a number of blocks of a system proceeding from technological (economical) reasons; (b) using the proposed synthesis method, to find an orientation of site magnetization providing maximum possible effect of magnet utilization in a system obtained in (a). Such approach considerably reduces a time of MSs projecting and guarantees maximal possible efficiency of magnets utilization. Besides it provides absolute assurance in 'ideality' of a MS design and allows to obtain an exact estimate of the limit parameters of a field in a working area of a projected MS. The method is applicable to a system containing the components from soft magnetic material with linear magnetic properties

  8. Plasma-assisted synthesis and study of structural and magnetic properties of Fe/C core shell

    Science.gov (United States)

    Shinde, K. P.; Ranot, M.; Choi, C. J.; Kim, H. S.; Chung, K. C.

    2017-07-01

    Pure and carbon-encapsulated iron nanoparticles with an average diameter of 25 nm were synthesized by using the DC plasma arc discharge method. Fe core nanoparticles were encapsulated with carbon layer, which is acting as protection layer against both oxidation and chemical reaction. The morphology and the Fe/C core/shell structure of the nanoparticles were studied by using field emission scanning electron microscopy and transmission electron microscopy. The x-ray diffraction study showed that the α-Fe phase exists with γ-Fe as an impurity. The studied samples have been interrelated with the variation of saturation magnetization, remanent magnetization and coercive field with the amount of carbon coating. The pure α-Fe sample shows saturation magnetization = 172 emu/g, and coercive field = 150 Oe, on the other hand few layer carbon coated α-Fe sample shows saturation magnetization =169 emu/g with higher coercive field 398 Oe.

  9. Plasma-assisted synthesis and study of structural and magnetic properties of Fe/C core shell

    Directory of Open Access Journals (Sweden)

    K. P. Shinde

    2017-07-01

    Full Text Available Pure and carbon-encapsulated iron nanoparticles with an average diameter of 25 nm were synthesized by using the DC plasma arc discharge method. Fe core nanoparticles were encapsulated with carbon layer, which is acting as protection layer against both oxidation and chemical reaction. The morphology and the Fe/C core/shell structure of the nanoparticles were studied by using field emission scanning electron microscopy and transmission electron microscopy. The x-ray diffraction study showed that the α-Fe phase exists with γ-Fe as an impurity. The studied samples have been interrelated with the variation of saturation magnetization, remanent magnetization and coercive field with the amount of carbon coating. The pure α-Fe sample shows saturation magnetization = 172 emu/g, and coercive field = 150 Oe, on the other hand few layer carbon coated α-Fe sample shows saturation magnetization =169 emu/g with higher coercive field 398 Oe.

  10. Superconducting selenides intercalated with organic molecules: synthesis, crystal structure, electric and magnetic properties, superconducting properties, and phase separation in iron based-chalcogenides and hybrid organic-inorganic superconductors

    Science.gov (United States)

    Krzton-Maziopa, Anna; Pesko, Edyta; Puzniak, Roman

    2018-06-01

    Layered iron-based superconducting chalcogenides intercalated with molecular species are the subject of intensive studies, especially in the field of solid state chemistry and condensed matter physics, because of their intriguing chemistry and tunable electric and magnetic properties. Considerable progress in the research, revealing superconducting inorganic–organic hybrid materials with transition temperatures to superconducting state, T c, up to 46 K, has been brought in recent years. These novel materials are synthesized by low-temperature intercalation of molecular species, such as solvates of alkali metals and nitrogen-containing donor compounds, into layered FeSe-type structure. Both the chemical nature as well as orientation of organic molecules between the layers of inorganic host, play an important role in structural modifications and may be used for fine tuning of superconducting properties. Furthermore, a variety of donor species compatible with alkali metals, as well as the possibility of doping also in the host structure (either on Fe or Se sites), makes this system quite flexible and gives a vast array of new materials with tunable electric and magnetic properties. In this review, the main aspects of intercalation chemistry are discussed with a particular attention paid to the influence of the unique nature of intercalating species on the crystal structure and physical properties of the hybrid inorganic–organic materials. To get a full picture of these materials, a comprehensive description of the most effective chemical and electrochemical methods, utilized for synthesis of intercalated species, with critical evaluation of their strong and weak points, related to feasibility of synthesis, phase purity, crystal size and morphology of final products, is included as well.

  11. 1D and 2D Cobalt(II) Coordination Polymers, Co(ox)(en):Synthesis, Structures and Magnetic Properties

    International Nuclear Information System (INIS)

    Kang, Jae Un; Lee, Yu Mi; Kim, Seung Joo; Yun, Ho Seop; Do, Jung Hwan

    2014-01-01

    Two ethylenediamine cobalt(II) oxalate complexes Co(ox)(en), 1 and Co(ox)(en)·2H 2 O, 2 have been hydrothermally synthesized and characterized by single crystal X-ray diffraction, IR spectrum, TG analysis, and magnetic measurements. In 1, Co atoms are coordinated by two bis-bidentate oxalate ions in transconfiguration to form Co(ox) chains, which are further bridged by ethylenediamine molecules to produce 2D grid layers, Co(ox)(en). In 2, Co atoms are coordinated by bridging oxalate ions in cis - configuration to form Co(ox) chains, and the additional chelation of ethylenediamine to Co atoms completes 1D zigzag chain, Co(en)(ox). Two lattice water molecules stabilize the chains through hydrogen bonding. Magnetic susceptibility measurements indicate that both complexes exhibit weak antiferromagnetic coupling between cobalt(II) ions with the susceptibility maxima at 23 K for 1 and 20 K for 2, respectively. In 1 and 2, the oxalate ligands afford a much shorter and more effective pathway for the magnetic interaction between cobalt ions compared to the ethylenediamine ligands, so the magnetic behaviors of both complexes could be well described with 1D infinite magnetic chain model

  12. Wet chemical synthesis and magnetic properties of single crystal Co nanochains with surface amorphous passivation Co layers

    Directory of Open Access Journals (Sweden)

    Zhou Shao-Min

    2011-01-01

    Full Text Available Abstract In this study, for the first time, high-yield chain-like one-dimensional (1D Co nanostructures without any impurity have been produced by means of a solution dispersion approach under permanent-magnet. Size, morphology, component, and structure of the as-made samples have been confirmed by several techniques, and nanochains (NCs with diameter of approximately 60 nm consisting of single-crystalline Co and amorphous Co-capped layer (about 3 nm have been materialized. The as-synthesized Co samples do not include any other adulterants. The high-quality NC growth mechanism is proposed to be driven by magnetostatic interaction because NC can be reorganized under a weak magnetic field. Room-temperature-enhanced coercivity of NCs was observed, which is considered to have potential applications in spin filtering, high density magnetic recording, and nanosensors. PACS: 61.46.Df; 75.50; 81.07.Vb; 81.07.

  13. Self-propagating high temperature synthesis and magnetic

    Indian Academy of Sciences (India)

    Ni–Zn ferrite powders were synthesized by self-propagating high temperature synthesis (SHS) method. X-ray diffraction, TEM and vibrating sample magnetometry (VSM) were used to characterize the phase composition, microstructure and magnetic properties of the combustion products. The effect of the combustion ...

  14. Synthesis of nanoparticles of manganese MnFe2O4 by co-precipitation micellar ferrite: structural and magnetic properties

    International Nuclear Information System (INIS)

    Alvarez-Paneque, A.; Diaz, S.; Diaz, C.; Santiago-Jacinto, E.; Reguera, E.

    2008-01-01

    Full text: The microemulsion method was used in reverse, shaped micelles by dodecyl of sodium (NaDBS) in toluene/water system, for MnFe2O4 manganese ferrite magnetic nanoparticles. Were also variants of heat treatments to improve the crystallinity of the material obtained. These were, treatments to reflux to 100 ° C or treatments in an inert atmosphere at temperatures that were varied between 350 and 600 ° C. The retrieved material was characterized by x-ray diffraction (XRD), transmission electron microscopy of high and low resolution (HR-TEM and TEM, respectively), Mössbauer Spectroscopy and vibrational magnetometry. Powder XRD patterns revealed the formation of phase MnFe2O4, cubic type Spinel, of space group Fd3m, accompanied by the minority phase Hematite (a-Fe203) group spatial R-3 c. The size of the nanoparticles was estimated from the profile setting from the pattern of powder by the method of Le Bail, obtaining sizes mean that varied between 5 and 25 mn depending on the heat treatment to which they were subjected. This result was corroborated from TEM micrographs. The vibrational magnetometer showed that the smaller MnFe2O4 nanoparticles, prepared following this route of synthesis They presented a superparamagnetic behavior at room temperature (coercive field and) remanence approximately zeros), which was also confirmed by the study of Mössbauer Spectroscopy. Was also the magnetically inactive layer thickness, of around 0.9 nm, responsible for the decrease in the values of saturation magnetization (as) to decrease the size of nanoparticles. Was obtained a set of nanoparticles with superparamagnetic behavior based in the MnFe2O4 around 5.9 NM in diameter and a-Fe203 around 6.6 NM, as phase secondary. They managed to get this material and the desired magnetic properties optimum crystallinity, applying heat treatment variant proposed in this work, and that It consists of making a reflux at 100 ° C, before the treatment on solid phase under flow N2

  15. Synthesis and magnetic properties of (Eu–Ni) substituted Y-type hexaferrite by surfactant assisted co-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Irshad, E-mail: irshadalibzu@gmail.com [Department of Physics, BahauddinZakariya University, Multan, P.O# 60800 (Pakistan); Islam, M.U. [Department of Physics, BahauddinZakariya University, Multan, P.O# 60800 (Pakistan); Sadiq, Imran [Department of Physics, BahauddinZakariya University, Multan, P.O# 60800 (Pakistan); Centre of Excellence in Solid State Physics, University of The Punjab, Lahore (Pakistan); Karamat, Nazia [Institute of Chemical Science, Bahauddin Zakariya University, Multan 60800 (Pakistan); Iftikhar, Aisha [Department of Physics, BahauddinZakariya University, Multan, P.O# 60800 (Pakistan); Khan, M. Azhar [Department of Physics, Islamia University of Bahawalpur, 63100 Pakistan (Pakistan); Shah, Afzal [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Athar, Muhammad [Institute of Chemical Science, Bahauddin Zakariya University, Multan 60800 (Pakistan); Shakir, Imran [Sustainable Energy Technologies (SET) Center, College of Engineering, King Saud University (Saudi Arabia); Ashiq, Muhammad Naeem, E-mail: naeemashiqqau@yahoo.com [Institute of Chemical Science, Bahauddin Zakariya University, Multan 60800 (Pakistan)

    2015-07-01

    A series of (Eu–Ni) substituted Y-type hexaferrite with composition Sr{sub 2}Co{sub (2−x)}Ni{sub x}Eu{sub y}Fe{sub (12−y)}O{sub 22} (x=0.0–1, Y=0.0–0.1) were prepared by the surfactant assisted co-precipitation method. The present samples were sintered at 1050 °C for 8 h. The shape of the particles is plate-like which is very advantageous for various applications and the grain size varies from 73 to 269 nm. The values of saturation magnetization (M{sub s}), remanent magnetization (M{sub r}) and magnetic moment (n{sub B}) were found to decrease which are attributed to the weakening of super exchange interactions. The values of in-plane Squareness ratios (M{sub r}/M{sub s}) ranging from 0.41 to 0.65 whereas in case of out of plane measurement it varies from 0.30 to 0.62.The investigated samples can be used in perpendicular recording media (PRM) due to high value of coercivity 2300 Oe which is analogous to the those of M-type and W-type hard magnetic. - Highlights: • The present samples sintered at 1050 °C for 8 h. • The grain size varies from 73 to 269 nm. • The magnetic moment varies from 15.27 to 6.07. • The shape of grains is plate like for microwave devices. • The present samples can be used in PRM due to high value of coercivity i.e. 2300 Oe.

  16. Facile synthesis of Ca-doped manganite nanoparticles by a nonaqueous sol-gel method and their magnetic properties

    International Nuclear Information System (INIS)

    Zhou, S.M.; Zhao, S.Y.; He, L.F.; Guo, Y.Q.; Shi, L.

    2010-01-01

    Perovskite manganite La 1-x Ca x MnO 3 (x=1/3, 1/2 and 2/3) nanoparticles with the average particle size of about 20 nm have been synthesized by a facile nonaqueous sol-gel method using methanol as a solvent and characterized by X-ray diffraction, transmission electron microscopy and superconducting quantum interference device magnetometer. Magnetic measurements reveal that although their bulk counterparts have quite different magnetic ground states, the three-nanosized samples exhibit similar ferromagnetic behaviors below about 270 K. This result implies that with the particle size reduced to nanoscale, the ferromagnetism for x=1/3 is weaken, while it is enhanced, accompanied by the suppression of the charge ordering, for x=1/2 and 2/3. Moreover, the exchange bias phenomena are observed in the two latter nanoparticles, which is of special interest for potential applications.

  17. Synthesis, Crystal Structures, Magnetic Properties, and Theoretical Investigation of a New Series of NiII-LnIII-WV Heterotrimetallics: Understanding the SMM Behavior of Mixed Polynuclear Complexes.

    Science.gov (United States)

    Vieru, Veacheslav; Pasatoiu, Traian D; Ungur, Liviu; Suturina, Elizaveta; Madalan, Augustin M; Duhayon, Carine; Sutter, Jean-Pascal; Andruh, Marius; Chibotaru, Liviu F

    2016-12-05

    The polynuclear compounds containing anisotropic metal ions often exhibit efficient barriers for blocking of magnetization at fairly arbitrary geometries. However, at variance with mononuclear complexes, which usually become single-molecule magnets (SMM) under the sole requirement of a highly axial crystal field at the metal ion, the factors influencing the SMM behavior in polynuclear complexes, especially, with weakly axial magnetic ions, still remain largely unrevealed. As an attempt to clarify these conditions, we present here the synthesis, crystal structures, magnetic behavior, and ab initio calculations for a new series of Ni II -Ln III -W V trimetallics, [(CN) 7 W(CN)Ni(H 2 O)(valpn)Ln(H 2 O) 4 ]·H 2 O (Ln = Y 1, Eu 2, Gd 3, Tb 4, Dy 5, Lu 6). The surprising finding is the absence of the magnetic blockage even for compounds involving strongly anisotropic Dy III and Tb III metal ions. This is well explained by ab initio calculations showing relatively large transversal components of the g-tensor in the ground exchange Kramers doublets of 1 and 4 and large intrinsic tunneling gaps in the ground exchange doublets of 3 and 5. In order to get more insight into this behavior, another series of earlier reported compounds with the same trinuclear [W V Ni II Ln III ] core structure, [(CN) 7 W(CN)Ni(dmf)(valdmpn)Ln(dmf) 4 ]·H 2 O (Ln = Gd III 7, Tb III 8a, Dy III 9, Ho III 10), [(CN) 7 W(CN)Ni(H 2 O)(valdmpn)Tb(dmf) 2.5 (H 2 O) 1.5 ]·H 2 O·0.5dmf 8b, and [(CN) 7 W(CN)Ni(H 2 O)(valdmpn)Er(dmf) 3 (H 2 O) 1 ]·H 2 O·0.5dmf 11, has been also investigated theoretically. In this series, only 8b exhibits SMM behavior which is confirmed by the present ab initio calculations. An important feature for the entire series is the strong ferromagnetic coupling between Ni(II) and W(V), which is due to an almost perfect trigonal dodecahedron geometry of the octacyano wolframate fragment. The reason why only 8b is an SMM is explained by positive zero-field splitting on the nickel

  18. Synthesis and magnetic properties of the thin film exchange spring system of MnBi/FeCo

    Science.gov (United States)

    Sabet, S.; Hildebrandt, E.; Alff, L.

    2017-10-01

    Manganese bismuth thin films with a nominal thickness of ∼40 nm were grown at room temperature onto quartz glass substrate in a DC magnetron sputtering unit. In contrast to the usual multilayer approach, the MnBi films were deposited using a single sputtering target with a stoichiometry of Mn55Bi45 (at. %). A subsequent in-situ annealing step was performed in vacuum in order to form the ferromagnetic LTP of MnBi. X-ray diffraction confirmed the formation of a textured LTP MnBi hard phase after annealing at 330 °C. This film shows a maximum saturation magnetization of 530 emu/cm3, high out-of-plane coercivity of 15 kOe induced by unreacted bismuth. The exchange coupling effect was investigated by deposition of a second layer of FeCo with 1 nm and 2 nm thickness onto the LTP MnBi films. The MnBi/FeCo double layer showed as expected higher saturation magnetization with increasing thickness of the FeCo layer while the coercive field remained constant. The fabrication of the MnBi/FeCo double layer for an exchange spring magnet was facilitated by deposition from a single stoichiometric target.

  19. Facile hydrothermal synthesis of alpha manganese sesquioxide (α-Mn2O3) nanodumb-bells: Structural, magnetic, optical and photocatalytic properties

    International Nuclear Information System (INIS)

    Gnanam, S.; Rajendran, V.

    2013-01-01

    Highlights: ► α-Mn 2 O 3 nanoparticles sizes of 35–42 nm have been prepared by hydrothermal process. ► Shapes of α-Mn 2 O 3 : Dumb-bell, Cauliflower, spherical with rod, spherical with wires. ► The strong UV emission can be attributed to high purity and perfect crystallinity. ► Photocatalytic activity of α–Mn 2 O 3 was studied by degradation of Remazol red B dye. - Abstract: Nanometer scale cubic bixbyite α-Mn 2 O 3 has been synthesized by a facile hydrothermal method, at a temperature of 450 °C in the presence of various surfactants. The X-ray diffraction (XRD) analysis shows that the average crystallite size of the sample is ∼35–42 nm. The shapes of the α-Mn 2 O 3 nanoparticles include: Dumb-bell-like (anionic surfactant), Cauliflower-like (nonionic surfactant), spherical with rods (cationic surfactant) and spherical with wires (surface modifier). The shapes of α-Mn 2 O 3 nanoparticles depend on the type of surfactant used in the synthesis. The magnetic property of the anionic surfactant assisted sample was primarily studied, using the vibrating sample magnetometer (VSM). The optical absorption spectra confirmed the effectiveness of the selected capping agents, as the anionic capped α-Mn 2 O 3 colloids absorbed at shorter wavelength than the other agents, indicating a much smaller crystallite size. The property of strong UV emissions may be attributed to the high purity and perfect crystallinity of the as-prepared α-Mn 2 O 3 . The surfactants-assisted catalyst was tested for its photocatalytic activity towards the photodegradation of the harmful organic dye Remazol Red B, using a multilamp photo reactor. Possible formation mechanisms have also been proposed for the as-synthesized anionic surfactant assisted samples.

  20. Detonation-synthesis nanodiamonds: synthesis, structure, properties and applications

    Energy Technology Data Exchange (ETDEWEB)

    Dolmatov, Valerii Yu [Federal State Unitary Enterprise Special Design-Technology Bureau (FSUE SDTB) ' ' Tekhnolog' ' at the St Petersburg State Institute of Technology (Technical University) (Russian Federation)

    2007-04-30

    The review outlines the theoretical foundations and industrial implementations of modern detonation synthesis of nanodiamonds and chemical purification of the nanodiamonds thus obtained. The structure, key properties and promising fields of application of detonation-synthesis nanodiamonds are considered.

  1. Detonation-synthesis nanodiamonds: synthesis, structure, properties and applications

    International Nuclear Information System (INIS)

    Dolmatov, Valerii Yu

    2007-01-01

    The review outlines the theoretical foundations and industrial implementations of modern detonation synthesis of nanodiamonds and chemical purification of the nanodiamonds thus obtained. The structure, key properties and promising fields of application of detonation-synthesis nanodiamonds are considered.

  2. Magnetic properties of iron nanoparticle

    International Nuclear Information System (INIS)

    Carvell, J.; Ayieta, E.; Gavrin, A.; Cheng, Ruihua; Shah, V. R.; Sokol, P.

    2010-01-01

    Magnetic properties of Fe nanoparticles with different sizes synthesized by a physical deposition technique have been investigated experimentally. We have used a high pressure sputtering technique to deposit iron nanoparticles on a silicon substrate. The nanoparticles are then analyzed using atomic force microscopy (AFM), transmission electron microscopy (TEM), and superconducting quantum interference device techniques. TEM and AFM data show that the particle size could be tuned by adjusting the deposition conditions. The magnetic properties have been investigated from temperature dependent magnetization M(T) and field dependent magnetization M(H) measurements. The results show that two phases including both ferromagnetic and superparamagnetic particles are present in our system. From these data we extracted the superparamagnetic critical size to be 9 nm for our samples. Ferromagnetic particles are single magnetic domain particles and the magnetic properties can be explained by the Stoner and Wohlfarth model. For the superparamagnetic phase, the effective anisotropy constant, K eff , decreases as the particle size increases.

  3. Template Synthesis, Crystal Structure, and Magnetic Properties of a Dinuclear Copper(II) Complex with Cooperative Hydrogen Bonding

    International Nuclear Information System (INIS)

    Kang, Shin Geol; Nam, Kwang Hee; Min, Kil Sik; Lee, Uk

    2011-01-01

    The dinuclear complex with cooperative hydrogen bonds can be prepared by the metal-directed reaction of Eq. This work shows that the coordinated hydroxyl group trans to the secondary amino group is deprotonated more readily than that trans to the tertiary amino group and acts as the hydrogen-bond accepter. The lattice water molecules in act as bridges between the two mononuclear units through hydrogen bonds. The complex is quite stable as the dimeric form even in various polar solvents. The complex exhibits a weak antiferromagnetic interaction between the metal ions in spite of relatively long Cu···Cu distance. This strongly supports the suggestion that the antiferromagnetic behavior is closely related to the cooperative hydrogen bonds. The design and synthesis of polynuclear transition metal complexes have received much attention because of their potential applications in various fields, such as catalysis, supramolecular chemistry, and materials chemistry. Until now, various types of dinuclear copper(II) complexes have been prepared and investigated. Some dinuclear copper(II) complexes resulting from cooperative hydrogen bonding, such as containing two N_2O_2 donor sets, are also reported

  4. Progress in electrochemical synthesis of magnetic iron oxide nanoparticles

    International Nuclear Information System (INIS)

    Ramimoghadam, Donya; Bagheri, Samira; Hamid, Sharifah Bee Abd

    2014-01-01

    Recently, magnetic iron oxide particles have been emerged as significant nanomaterials due to its extensive range of application in various fields. In this regard, synthesis of iron oxide nanoparticles with desirable properties and high potential applications are greatly demanded. Therefore, investigation on different iron oxide phases and their magnetic properties along with various commonly used synthetic techniques are remarked and thoroughly described in this review. Electrochemical synthesis as a newfound method with unique advantages is elaborated, followed by design approaches and key parameters to control the properties of the iron oxide nanoparticles. Additionally, since the dispersion of iron oxide nanoparticles is as important as its preparation, surface modification issue has been a serious challenge which is comprehensively discussed using different surfactants. Despite the advantages of the electrochemical synthesis method, this technique has been poorly studied and requires deep investigations on effectual parameters such as current density, pH, electrolyte concentration etc. - Highlights: • IONPs are applied in chemical industries, medicine, magnetic storage etc. • Electrochemical synthesis (EC) is convenient, eco-friendly, selective and low-cost. • EC key factors are current density, pH, electrolyte concentration, electrode type. • Organic, inorganic and biological materials can be used to modify IONPs’ surface. • The physicochemical properties of IONPs can be controlled by adding surfactants

  5. Synthesis, characterization and magnetic properties of novel μ-oxamido heterodinuclear copper(II) - lanthanide(III) complexes

    International Nuclear Information System (INIS)

    Li, Y.T.; Miao, M.M.; Liao, D.Z.; Jiang, Z.H.; Wang, G.L.

    1995-01-01

    Six novel μ-oxamido heterobinuclear complexes have been prepared and identified as Cu(oxpn)Ln(L) 2 (ClO 4 ) 3 , where oxpn denotes the N, N'-bis(3-aminopropyl)oxamido dianion, L, 1,10-phenanthroline (phen) and Ln stands for La, Nd, Gd, Tb, Ho, Er. The complexes Cu(oxpn)Gd(oxpn)Gd(phen) 2 (ClO 4 ) 3 were characterized with variable temperature magnetic susceptibility (4-300 K). The exchange integral J (Cu-Gd) was found to be 2.03 cm -1 . The result is commensurate with ferromagnetic interaction between the adjacent metal ions. One plausible mechanism that can cause a ferromagnetic coupling between Gd(III) and Cu(II) is also discussed in terms of spin polarized. (author). 32 refs, 3 figs, 3 tabs

  6. Synthesis, structural, magnetic and optical properties of Sr2CoSn based inverse Heusler alloy nanoparticles

    Science.gov (United States)

    Asvini, V.; Saravanan, G.; Kalaiezhily, R. K.; Ravichandran, K.

    2018-05-01

    The peculiar ternary full Heusler alloy Sr2CoSn nanoparticles are synthesized by co-precipitation method. X- ray diffraction pattern confirms the formation of XA or Xα structure of Sr2CoSn. Using Williamson-Hall plot (W-H plot), we are able to use the uniform deformation model and get low value of strain induced broadening. UV-Visible absorption spectrum shows sharp absorption peak at 210 nm and the estimated band gap energy of Sr2CoSn Heusler alloy nanoparticles is Eg = 4.6 eV (from Tauc plot). The presence of Sr2CoSn with the particle size of approximately 90 nm was observed using high resolution scanning electron microscopy. The magnetization measurements were carried out using VSM and studied M verses H hysteresis studies.

  7. Sol-gel synthesis of 8 nm magnetite (Fe 3O 4) nanoparticles and their magnetic properties

    KAUST Repository

    Lemine, O. M.

    2012-10-01

    Magnetite (Fe 3O 4) nanoparticles were successfully synthesized by a sol-gel method. The obtained nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive analysis by X-ray (EDAX), transmission electron microscopy (TEM), superconducting quantum interference device (SQUID) and Mössbauer spectrometry. XRD and Mössbauer measurements indicate that the obtained nanoparticles are single phase. TEM analysis shows the presence of spherical nanoparticles with homogeneous size distribution of about 8 nm. Room temperature ferromagnetics behavior was confirmed by SQUID measurements. The mechanism of nanoparticles formation and the comparison with recent results are discussed. Finally, the synthesized nanoparticles present a potential candidate for hyperthermia application given their saturation magnetization. © 2012 Elsevier Ltd. All rights reserved.

  8. Sol-gel synthesis of 8 nm magnetite (Fe 3O 4) nanoparticles and their magnetic properties

    KAUST Repository

    Lemine, O. M.; Omri, Karim; Zhang, Bei; El Mir, Lassaad; Sajieddine, Mohammed; Alyamani, Ahmed Y.; Bououdina, M.

    2012-01-01

    Magnetite (Fe 3O 4) nanoparticles were successfully synthesized by a sol-gel method. The obtained nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive analysis by X-ray (EDAX), transmission electron microscopy (TEM), superconducting quantum interference device (SQUID) and Mössbauer spectrometry. XRD and Mössbauer measurements indicate that the obtained nanoparticles are single phase. TEM analysis shows the presence of spherical nanoparticles with homogeneous size distribution of about 8 nm. Room temperature ferromagnetics behavior was confirmed by SQUID measurements. The mechanism of nanoparticles formation and the comparison with recent results are discussed. Finally, the synthesized nanoparticles present a potential candidate for hyperthermia application given their saturation magnetization. © 2012 Elsevier Ltd. All rights reserved.

  9. Unexpected ferromagnetic interaction in a new tetranuclear copper(II) complex: synthesis, crystal structure, magnetic properties, and theoretical studies.

    Science.gov (United States)

    Fondo, Matilde; García-Deibe, Ana M; Corbella, Monstserrat; Ruiz, Eliseo; Tercero, Javier; Sanmartín, Jesús; Bermejo, Manuel R

    2005-07-11

    The new tetranuclear carbonate complex [Cu2L)2(CO3)] x 8H2O (1 x 8H2O) (H3L = (2-(2-hydroxyphenyl)-1,3-bis[4-(2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine) has been obtained by two different synthetic routes and fully characterized. Recrystallization of 1 x 8H2O in methanol yields single crystals of {[(Cu2L)2(CO3)]}2 x 12H2O (1 x 6H2O), suitable for X-ray diffraction studies. The crystal structure of 1 x 6H2O shows two crystallographically different tetranuclear molecules in the asymmetric unit, 1a and 1b. Both molecules can be understood as self-assembled from two dinuclear [Cu2L]+ cations, joined by a mu4-eta(2):eta(1):eta(1) carbonate ligand. The copper atoms of each crystallographically different [(Cu2L)2(CO3)] molecule present miscellaneous coordination polyhedra: in both 1a and 1b, two metal centers are in square pyramidal environments, one displays a square planar chromophore and the other one has a geometry that can be considered as an intermediate between square pyramid and trigonal bipyramid. Magnetic studies reveal net intramolecular ferromagnetic coupling between the metal atoms. Density functional calculations allow the assignment of the different magnetic coupling constants and explain the unexpected ferromagnetic behavior, because of the presence of an unusual NCN bridging moiety and countercomplementarity of the phenoxo (or carbonate) and NCN bridges.

  10. Construction of three lanthanide metal-organic frameworks: Synthesis, structure, magnetic properties and highly selective sensing of metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiu-Mei, E-mail: zhangxiumeilb@126.com; Li, Peng; Gao, Wei; Liu, Feng; Liu, Jie-Ping

    2016-12-15

    Three lanthanide metal-organic frameworks (Ln-MOFs), [Ln(TZI)(H{sub 2}O){sub 4}]·3H{sub 2}O (Ln=Gd (1) and Tb (2) and Dy (3), H{sub 3}TZI=5-(1H-tetrazol-5-yl)isophthalic acid), have been synthesized under hydrothermal conditions. Single crystal X-ray diffraction reveals that 1–3 are isostructural and display a 1D double chain based on dinuclear motifs with (μ-COO){sub 2} double bridges. Magnetic studies indicate antiferromagnetic interactions in 1, ferromagnetic interactions in 2 and 3. Furthermore, compound 3 displays a slow relaxation behavior. Compound 2 exhibits intense characteristic green emission of Tb(III) ions in the solid state, which can be observed by the naked eye under UV light. Interestingly, 2 can selectively sense Pb{sup 2+} and Fe{sup 3+} ions through luminescence enhancement and quenching, respectively. The luminescence quenching mechanisms have been investigated in detail. The study on luminescence Ln-MOFs as a probe for sensing Pb{sup 2+} and Fe{sup 3+} ions is exceedingly rare example. - Graphical abstract: Three Ln-MOFs were successfully synthesized using a 5-(1H-tetrazol-5-yl)isophthalic acid ligand. They displays different magnetic behavior. Especially, the Dy(III) compound slow relaxation behavior. Interestingly, the Tb(III) compound can selectively sense Pb{sup 2+} and Fe{sup 3+} ions through luminescence enhancement and quenching, respectively. - Highlights: • Three Ln-MOFs with tetrazolate dicarboxylate ligand. • Dy(III) compound displays slow relaxation behavior. • The Tb(III) compound shows highly selective luminescence sensing of the Fe{sup 3+} and Pb{sup 2+} ions.

  11. Synthesis, structure, magnetic, electrical and electrochemical properties of Al, Cu and Mg doped MnO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Hashem, Ahmed M., E-mail: ahmedh242@yahoo.com [National Research Centre, Inorganic Chemistry Department, Behoes St., Dokki, Cairo (Egypt); Institute for Complex Materials, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Abuzeid, Hanaa M. [National Research Centre, Inorganic Chemistry Department, Behoes St., Dokki, Cairo (Egypt); Narayanan, N. [Institute for Complex Materials, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Ehrenberg, Helmut [Institute for Complex Materials, IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Materials Science, Technische Universitaet Darmstadt, Petersenstr. 23, D-64287 Darmstadt (Germany); Julien, C.M. [Universite Pierre et Marie Curie, Physicochimie des Electrolytes, Colloides et Sciences Analytiques (PECSA), 4 place Jussieu, 75005 Paris (France)

    2011-10-17

    Highlights: {yields} Al, Mg and Cu doped MnO{sub 2} as cathode in Li-ion batteries. {yields} Pure phase MnO{sub 2} for virgin and doped MnO{sub 2} were obtained. {yields} Doping elements improve the electrical conductivity of MnO{sub 2}. {yields} Electrochemical behaviour of MnO{sub 2} improved after doping by Al, Mg and Cu. - Abstract: Pure and doped manganese dioxides were prepared by wet-chemical method using fumaric acid and potassium permanganate as raw materials. X-ray diffraction patterns show that pure and Al, Cu and Mg doped manganese dioxides (d-MnO{sub 2}) crystallized in the cryptomelane-MnO{sub 2} structure. Thermal analysis show that, with the assistance of potassium ions inside the 2 x 2 tunnel, the presence of Al, Cu and Mg doping elements increases the thermal stability of d-MnO{sub 2}. The electrical conductivity of d-MnO{sub 2} increases in comparison with pure MnO{sub 2}, while Al-doped MnO{sub 2} exhibits the lower resistivity. As shown in the magnetic measurements, the value of the experimental effective magnetic moment of Mn ions decreases with introduction of dopants, which is attributed to the presence of a mixed valency of high-spin state Mn{sup 4+}/Mn{sup 3+}. Doped MnO{sub 2} materials show good capacity retention in comparison with virgin MnO{sub 2}. Al-doped MnO{sub 2} shows the best electrochemical results in terms of capacity retention and recharge efficiency.

  12. Assembling Metal Ions Induced Cyanide-Bridged Heterometallic 1D and Ion-Pair Complexes: Synthesis, Crystal Structures and Magnetic Properties

    International Nuclear Information System (INIS)

    Kong, Lingqian; Zhao, Zengdian; Chen, Kexun; Wang, Ping; Zhang, Daopeng

    2013-01-01

    We obtained a heterobimetallic one-dimensional cyanide-bridged Mn(II)-Ni(II) complex and an Co(III)-Ni(II) ion-pair complex with [Ni(CN) 4 ] 2- as building block and M(II)-phenanthroline (M = Mn, Co) compounds as assembling segment. The different structural types of complexes 1 and 2 indicate that the property of the metal ions the assembling segment contained have obvious influence on the structure of the cyanide-bridged complex. Investigation over the magnetic properties of complex 1 reveals an overall weak antiferromagnetic coupling between the adjacent Mn(II) ions bridged by the antiferromagnetic [-NC-Ni-CN-] unit. Among of all the molecular magnetism systems, for the well known reasons, cyanide-containing complexes have been widely employed as bridges to assemble homo/hetero-metallic molecular magnetic materials by using the cyanide bridge transferring magnetic coupling between the neighboring paramagnetic ions, in whichsome showed interesting magnetic properties, such as high-Tc magnets, spin crossover materials, single-molecule magnets (SMMs) and single-chain magnets (SCMs)

  13. Assembling Metal Ions Induced Cyanide-Bridged Heterometallic 1D and Ion-Pair Complexes: Synthesis, Crystal Structures and Magnetic Properties

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Lingqian [Liaocheng Univ., Liaocheng (China); Zhao, Zengdian; Chen, Kexun; Wang, Ping; Zhang, Daopeng [Shandong Univ. of Technology, Zibo (China)

    2013-07-15

    We obtained a heterobimetallic one-dimensional cyanide-bridged Mn(II)-Ni(II) complex and an Co(III)-Ni(II) ion-pair complex with [Ni(CN){sub 4}]{sup 2-} as building block and M(II)-phenanthroline (M = Mn, Co) compounds as assembling segment. The different structural types of complexes 1 and 2 indicate that the property of the metal ions the assembling segment contained have obvious influence on the structure of the cyanide-bridged complex. Investigation over the magnetic properties of complex 1 reveals an overall weak antiferromagnetic coupling between the adjacent Mn(II) ions bridged by the antiferromagnetic [-NC-Ni-CN-] unit. Among of all the molecular magnetism systems, for the well known reasons, cyanide-containing complexes have been widely employed as bridges to assemble homo/hetero-metallic molecular magnetic materials by using the cyanide bridge transferring magnetic coupling between the neighboring paramagnetic ions, in whichsome showed interesting magnetic properties, such as high-Tc magnets, spin crossover materials, single-molecule magnets (SMMs) and single-chain magnets (SCMs)

  14. Self-assembly of novel manganese (II) compounds based on bifunctional-group ligands: Synthesis, structures, and magnetic properties

    Science.gov (United States)

    Yan, Juan-zhi; Lu, Li-ping; Zhu, Miao-li; Feng, Si-si

    2018-06-01

    Four manganese (II) compounds are obtained by the reaction of manganese salts, triazole-derivatives and auxiliary reagents in aqueous solution or mix-solvents by routine or hydrothermal reactions. X-ray crystal structure analyses reveal that a neutral 0D compound [Mn(Hmctrz)2(H2O)2] (1) (H2mctrz = 1H-1,2,4-triazole-3-carboxylic acid) displays a centro-symmetric mononuclear octahedral entity with two Hmctrz- anions and two water molecules; two neutral 2D clusters [Mn(Hdctrz)(H2O)2]n (2) (H3dctrz = 1H-1,2,4-triazole-3,5-dicarboxylic acid) and [Mn2(pbtrz)(btca)]n·4nH2O (3) (pbtrz = 1,3-bis(1,2,4-triazol-1-yl)-propane&H4btca = benzene-1,2,4,5-tetracarboxylic acid) possess layer structures with Hdctrz2- linkers (2) and Mn(II)-pbtrz-Mn(II) building blocks periodically extended by μ-btca4- connectors (3); [Mn(pbtrz)]n·nOAc·nOH (4) shows a 3D diamond-shaped cationic framework with the anion void volume of 49.2%. Nitrogenous bases are used as the auxiliary ligand in compound 3 and the temple ligand in compounds 1, 2, and 4. Compounds 1-4 show antiferromagnetic coupling that has been fitted by different models with the molecular field approximate with D = - 0.129(1) cm-1 for 1, J = - 0.354(4) cm-1 for 2 and J = - 0.696(6) cm-1 for 3, respectively. The magnetic differences can be related to different superexchange interactions transmitted by the crystal lattice and/or the zero field splitting (ZFS) of the 6A1g single-ion states of 1 and the syn-anti-COO- of 2 as well as the mixed magnetic bridges of μ1-O and μ-pbtrz-μ-COO- of 3.

  15. Magnetic nanomaterials undamentals, synthesis and applications

    CERN Document Server

    Sellmyer, David J

    2017-01-01

    Timely and comprehensive, this book presents recent advances in magnetic nanomaterials research, covering the latest developments, including the design and preparation of magnetic nanoparticles, their physical and chemical properties as well as their applications in different fields, including biomedicine, magnetic energy storage, wave–absorbing and water remediation. By allowing researchers to get to the forefront developments related to magnetic nanomaterials in various disciplines, this is invaluable reading for the nano, magnetic, energy, medical, and environmental communities.

  16. Hybrid nanostructures: synthesis, morphology and functional properties

    International Nuclear Information System (INIS)

    Povolotskaya, A V; Povolotskiy, A V; Manshina, A A

    2015-01-01

    Hybrid nanostructures representing combinations of different materials and possessing properties that are absent in separate components forming the hybrid are discussed. Particular attention is given to hybrid structures containing plasmonic and magnetic nanoparticles, methods of their synthesis and the relationship between the composition, structure and properties. The functional features of the hybrid nanomaterials of various morphology (with core–shell structures, with encapsulated metal nanoparticles and with metal nanoparticles on the surface) are considered. The unique properties of these hybrid materials are demonstrated, which are of interest for solving problems of catalysis and photocatalysis, detecting impurities in various media, in vivo visualization, bioanalysis, as well as for the design of optical labels and multifunctional diagnostic nanoplatforms. The bibliography includes 182 references

  17. Solvothermal synthesis of Zn1−xMnxO nanoparticles using oxalate precursor route: Optical and magnetic properties

    Directory of Open Access Journals (Sweden)

    Tokeer Ahmad

    2017-05-01

    Full Text Available Nanoparticles of Zn1−xMnxO (x = 0.022, 0.061 and 0.098 were synthesized by a modified solvothermal method through the oxalate precursor route. The precursors were characterized by TG/DTA analysis. Their kinetics has also been studied using the Freeman and Carroll method. The prepared oxide nanoparticles were investigated by powder X-ray diffraction (PXRD, transmission electron microscopy (TEM, optical and BET surface area studies. PXRD patterns were matched with hexagonal ZnO structure, however few impurity peaks of ZnMnO3 appeared. Reflectance measurements showed that Mn2+ is incorporated in the Zn matrix. The band gap decreases on increasing Mn concentration. The particle size decreases from 18 to 9 nm and the surface area increases (255.4–582.9 m2g−1 on increasing Mn concentration. All these solid solutions show paramagnetic behaviour with very weak antiferromagnetic interactions. The effective magnetic moment of these nanoparticles comes out to be 4.91, 4.77 and 4.18 μB/Mn2+.

  18. Synthesis, physical properties and band structure of non-magnetic Y{sub 3}AlC

    Energy Technology Data Exchange (ETDEWEB)

    Ghule, S.S. [Bharati Vidyapeeth Deemed University College of Engineering, Pune-Satara Road, Pune 411043 (India); Garde, C.S., E-mail: gardecs@gmail.com [Vishwakarma Institute of Information Technology, S. no. 2/3/4, Kondhwa(Bk), Pune 411048 (India); Ramakrishnan, S. [Tata Institute of Fundamental Research, Navynagar, Mumbai 400005 (India); Singh, S. [Indian Institute of Science Education and Research, Dr Homi Bhabha Road, Pashan, Pune 411008 (India); Rajarajan, A.K. [Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Laad, Meena [Symbiosis Institute of Technology (SIT), Symbiosis International University (SIU), Lavale, Pune 412115 (India)

    2016-10-01

    Y{sub 3}AlC has been synthesized by arc melting and subsequent annealing. Rietveld analysis of the powder x-ray diffraction (XRD) data confirms cubic Pm-3m structure. Electrical resistivity (ρ) of Y{sub 3}AlC exhibits metallic behaviour. No sign of superconductivity is observed down to the lowest measurement temperatures of 4.2 K in ρ, and 2 K in magnetic susceptibility (χ) and specific heat (C{sub p}) measurements. The value of the electronic specific heat coefficient γ is 1.36 mJ/K{sup 2} mol from which the density of states (DOS) at the Fermi energy (E{sub F}) is obtained as 0.57 states/eV.unit cell. The value of Debye temperature θ{sub D} is estimated to be 315 K. Electronic band structure calculations of Y{sub 3}AlC reveal a pseudo-gap in the DOS at E{sub F} leading to a small value of 0.5 states/eV unit cell which matches quite well with that obtained from γ. Non-zero value of the DOS indicates metallic behaviour as confirmed by our ρ data. Covalent and ionic bonding seem to co-exist with metallic bonding in Y{sub 3}AlC as indicated by van Arkel- Ketelaar triangle for Zintl-like systems.

  19. Two Organic Cation Salts Containing Tetra(isothiocyanatecobaltate(II: Synthesis, Crystal Structures, Spectroscopic, Optical and Magnetic Properties

    Directory of Open Access Journals (Sweden)

    Zheng Zhang

    2017-03-01

    Full Text Available Single crystals of two hybrid organic-inorganic molecular solids, benzyl pyridinium tetra(isothiocyanatecobalt ([BzPy]2[Co(NCS4] (1 and benzyl quinolinium tetra(isothiocyanatecobalt ([BzQl]2[Co(NCS4] (2, were grown using a slow evaporation growth technique at room temperature and their IR, UV-Vis, X-ray crystal structures, luminescence, and magnetism were reported. The crystal structural analysis revealed that two molecular solids crystallize in the monoclinic space group P21/c of 1 and P21/n of 2. The cations form a dimer through weak C–H···π/π···π interactions in 1 and 2, and the adjacent cation (containing N(6 atom in 2 forms a columnar structure through π···π weak interactions between the quinoline and benzene rings, while the anions in 1 form a layer structure via short S···Co interactions. The anions (A and cations (C are arranged alternatively into a column in the sequence of ···A–CC–A–CC–A··· for 1, while the two anions and cationic dimer in 2 form an alliance by the C–H···π, C–H···S and C–H···N hydrogen bonds. A weak S···π interaction was found in 1 and 2. The two molecular solids show a broad fluorescence emission around 400 nm in the solid state at room temperature, and weak antiferromagnetic coupling behavior when the temperature is lowered.

  20. Ibuprofen: Synthesis, production and properties

    Directory of Open Access Journals (Sweden)

    Mijin Dušan Ž.

    2003-01-01

    Full Text Available Since its introduction in 1969, ibuprofen has become one of the most common painkillers in the world. Ibuprofen in an NSAID (non-steroidal anti-inflammatory drug and like other drugs of its class it possesses analgetic, antipyretic and anti-inflammatory properties. While ibuprofen is a relatively simple molecule, there is still sufficient structural complexity to ensure that a large number of different synthetic approaches are possible. Since the introduction of pharmaceutical products containing ibuprofen, industrial and academic scientists have developed many potential production processes. This paper describes the history, synthesis and production, as well as the properties and stability of ibuprofen.

  1. Synthesis and characterization of structural and magnetic properties of polyaniline-cobalt ferrite (PA-CoFe) nanocomposites

    Science.gov (United States)

    Thakur, Sonika; Kaur, Parminder; Singh, Lakhwant

    2018-05-01

    The growing interest in the investigation of the properties of modified conducting polymers stems from their potential applications in various fields such as in sensing and catalytic devices. The present work reports the modification of conducting polymer polyaniline with cobalt ferrite (CoFe) nanoparticles, where CoFe nanoparticles are added in different successive weight percents. The composite samples were synthesized by in-situ chemical oxidative polymerization technique. The density of the samples has been found to increase with an increase in the CoFe content. Structural analysis of the synthesized sample has been done using X-ray diffraction studies. Perusal of the hysteresis curves of the prepared samples depicts that the introduction of CoFe into the polymer matrix leads to enhancement in the ferromagnetic behavior of the synthesized samples, suggesting that these nanocomposites have excellent microwave absorbing capacity.

  2. Synthesis and magnetic properties of hard magnetic (CoFe{sub 2}O{sub 4})-soft magnetic (Fe{sub 3}O{sub 4}) nano-composite ceramics by SPS technology

    Energy Technology Data Exchange (ETDEWEB)

    Fei Chunlong [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Hubei Key Laboratory on Organic and Polymeric Opto-electronic Materials, Wuhan University, Wuhan 430072 (China); Zhang Yue [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Hubei Key Laboratory on Organic and Polymeric Opto-electronic Materials, Wuhan University, Wuhan 430072 (China); Key Laboratory for the Green Preparation and Application of Functional Materials of Ministry of Education, Hubei University, Wuhan 430062 (China); Yang Zhi; Liu Yong [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Hubei Key Laboratory on Organic and Polymeric Opto-electronic Materials, Wuhan University, Wuhan 430072 (China); Xiong Rui, E-mail: wudawujiron@163.co [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Hubei Key Laboratory on Organic and Polymeric Opto-electronic Materials, Wuhan University, Wuhan 430072 (China) and Key Laboratory for the Green Preparation and Application of Functional Materials of Ministry of Education, Hubei University, Wuhan 430062 (China); Shi Jing [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Hubei Key Laboratory on Organic and Polymeric Opto-electronic Materials, Wuhan University, Wuhan 430072 (China); International Center for Materials Physics, Shen Yang 110015 (China); Ruan Xuefeng [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Hubei Key Laboratory on Organic and Polymeric Opto-electronic Materials, Wuhan University, Wuhan 430072 (China)

    2011-07-15

    CoFe{sub 2}O{sub 4}/Fe{sub 3}O{sub 4} nano-composite ceramics were synthesized by Spark Plasma Sintering. The X-ray diffraction patterns show that all samples are composed of CoFe{sub 2}O{sub 4} and Fe{sub 3}O{sub 4} phases when the sintering temperature is below 900 {sup o}C. It is found that the magnetic properties strongly depend on the sintering temperature. The two-step hysteresis loops for samples sintered below 500 {sup o}C are observed, but when sintering temperature reaches 500 {sup o}C, the step disappears, which indicates that the CoFe{sub 2}O{sub 4} and Fe{sub 3}O{sub 4} are well exchange coupled. As the sintering temperature increases from 500 to 800 {sup o}C, the results of X-ray diffractometer indicate the constriction of crystalline regions due to the ion diffusion at the interfaces of CoFe{sub 2}O{sub 4}/Fe{sub 3}O{sub 4} phases, which have great impact on the magnetic properties. - Research highlights: In this work, a series of CoFe{sub 2}O{sub 4}/Fe{sub 3}O{sub 4} nano-composite ceramics were prepared through SPS. The magnetic properties of these ceramics have been studied in detail. It is found that the magnetic properties strongly depend on the sintering temperature.

  3. Facile hydrothermal synthesis of alpha manganese sesquioxide ({alpha}-Mn{sub 2}O{sub 3}) nanodumb-bells: Structural, magnetic, optical and photocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Gnanam, S., E-mail: gnanam.nanoscience@gmail.com [Department of Physics, Presidency College, Chennai 600005, Tamilnadu (India); Rajendran, V. [Department of Physics, Presidency College, Chennai 600005, Tamilnadu (India)

    2013-02-15

    Highlights: Black-Right-Pointing-Pointer {alpha}-Mn{sub 2}O{sub 3} nanoparticles sizes of 35-42 nm have been prepared by hydrothermal process. Black-Right-Pointing-Pointer Shapes of {alpha}-Mn{sub 2}O{sub 3}: Dumb-bell, Cauliflower, spherical with rod, spherical with wires. Black-Right-Pointing-Pointer The strong UV emission can be attributed to high purity and perfect crystallinity. Black-Right-Pointing-Pointer Photocatalytic activity of {alpha}-Mn{sub 2}O{sub 3} was studied by degradation of Remazol red B dye. - Abstract: Nanometer scale cubic bixbyite {alpha}-Mn{sub 2}O{sub 3} has been synthesized by a facile hydrothermal method, at a temperature of 450 Degree-Sign C in the presence of various surfactants. The X-ray diffraction (XRD) analysis shows that the average crystallite size of the sample is {approx}35-42 nm. The shapes of the {alpha}-Mn{sub 2}O{sub 3} nanoparticles include: Dumb-bell-like (anionic surfactant), Cauliflower-like (nonionic surfactant), spherical with rods (cationic surfactant) and spherical with wires (surface modifier). The shapes of {alpha}-Mn{sub 2}O{sub 3} nanoparticles depend on the type of surfactant used in the synthesis. The magnetic property of the anionic surfactant assisted sample was primarily studied, using the vibrating sample magnetometer (VSM). The optical absorption spectra confirmed the effectiveness of the selected capping agents, as the anionic capped {alpha}-Mn{sub 2}O{sub 3} colloids absorbed at shorter wavelength than the other agents, indicating a much smaller crystallite size. The property of strong UV emissions may be attributed to the high purity and perfect crystallinity of the as-prepared {alpha}-Mn{sub 2}O{sub 3}. The surfactants-assisted catalyst was tested for its photocatalytic activity towards the photodegradation of the harmful organic dye Remazol Red B, using a multilamp photo reactor. Possible formation mechanisms have also been proposed for the as-synthesized anionic surfactant assisted samples.

  4. SYNTHESIS, CRYSTAL STRUCTURE AND MAGNETIC ...

    African Journals Online (AJOL)

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    Much of the current effort on such extended hybrid metal organic complexes is ... In this paper, we report the synthesis, single crystal X-ray diffraction analysis and ..... with g = 2.0 (0.37 cm3 mol−1 K), and smoothly increases to a value of 0.45 ...

  5. Synthesis, structure, optical, photoluminescence and magnetic properties of K2[Co(C2O4)2(H2O)2]·4H2O

    Science.gov (United States)

    Narsimhulu, M.; Hussain, K. A.

    2018-06-01

    The synthesis, crystal structure, optical, photoluminescence and magnetic behaviour of potassium bis(oxalato)cobaltate(II)tertrahydrate{K2[Co(C2O4)2(H2O)2]·4H2O} are described. The compound was grown at room temperature from mixture of aqueous solutions by slow evaporation method. The X-ray crystallographic data showed that the compound belongs to the monoclinic crystal system with P21/n space group and Z = 4. The UV-visible diffuse absorbance spectra exhibited bands at 253, 285 and 541 nm in the visible and ultraviolet regions. The optical band gap of the compound was estimated as 3.4 eV. At room temperature, an intense photoluminescence was observed from this material around 392 nm when it excited at 254 nm. The variable temperature dc magnetic susceptibility measurements exposed paramagnetic behaviour at high temperatures and antiferromagnetic ordering at low temperatures.

  6. The magnetic properties of the hollow cylindrical ideal remanence magnet

    DEFF Research Database (Denmark)

    Bjørk, Rasmus

    2016-01-01

    We consider the magnetic properties of the hollow cylindrical ideal remanence magnet. This magnet is the cylindrical permanent magnet that generates a uniform field in the cylinder bore, using the least amount of magnetic energy to do so. The remanence distribution of this magnet is derived...

  7. Properties and synthesis of milrinone

    Directory of Open Access Journals (Sweden)

    Mirković Jelena M.

    2013-01-01

    Full Text Available Milrinone, 1,6-dihydro-2-methyl-6-oxo-[3,4’-bipyridine]-5-carbonitrile, is a positive inotropic cardiotonic agent with vasodilator properties that acts as selective phosphodiesterase 3 inhibitor in cardiac and vascular smooth muscle. Trade names of milrinone are Primacor, Corotrop, Corotrope, and Milrila. Milrinone, an amrinone derivative, is 20 to 50 times more active than amrinone and possesses reduced propensity to side effects. The use of milrinone has created controversy in the medical as the result of increased mortality rate among patients that received high amounts of milrinone in oral form. Reaserch show that it can be benifitial for patients with severe congestive heart failure when used as short-time intravenous therapy. Milrinone properties, stability, as well as mechanism of action and synthesis under laboratory and industry conditions have been described in this paper. For industrial purposes milrinone is synthesized by condensation of cyanoacetamide with 4-(dimethylamino-3-(4-pyridinyl-3-buten-2-one and 4-ethoxy-3-(4-pyridinyl-3-buten-2-one in presence of a base, or by the reaction of 1-(4-pyridinyl- 2-propanone with ethoxymethylenmalononitrile or 4-alkoxy-3-(4-pyridinyl-3-buten-2-one with malononitrile without the use of external base. The starting compound for these syntheses is 4-picoline. Alternative synthesis of milrinone starts from 2-methyl-3-(4-pyridylidiene-1,1,5-tricyano-1,4-pentadiene-5-carboxamide and 2-methyl-6-oxo-1,6-dihydro-3,4’-bipyridine-5-carboxamide. Lastly, methods for milrinone synthesis in laboratory, injection preparation and purification have been summarized.

  8. Magnetic properties of hematite nanoparticles

    DEFF Research Database (Denmark)

    Bødker, Franz; Hansen, Mikkel Fougt; Bender Koch, Christian

    2000-01-01

    The magnetic properties of hematite (alpha-Fe2O3) particles with sizes of about 16 nm have been studied by use of Mossbauer spectroscopy, magnetization measurements, and neutron diffraction. The nanoparticles are weakly ferromagnetic at temperatures at least down to 5 K with a spontaneous...... magnetization that is only slightly higher than that of weakly ferromagnetic bulk hematite. At T greater than or similar to 100 K the Mossbauer spectra contain a doublet, which is asymmetric due to magnetic relaxation in the presence of an electric field gradient in accordance with the Blume-Tjon model......, Simultaneous fitting of series of Mossbauer spectra obtained at temperatures from 5 K to well above the superparamagnetic blocking temperature allowed the estimation of the pre-exponential factor in Neel's expression for the superparamagnetic relaxation time, tau(0) = (6 +/- 4) X 10(-11) s and the magnetic...

  9. Synthesis and properties of nickel cobalt boron nanoparticles

    Science.gov (United States)

    Patel, J.; Pankhurst, Q. A.; Parkin, I. P.

    2005-01-01

    Amorphous cobalt nickel boride nanoparticles were synthesised by chemical reduction synthesis in aqueous solution. Careful control of synthesis conditions and post reaction oxidation enabled the nanoparticles to be converted into a core-shell structure comprising of an amorphous Co-Ni-B core and an outer metal oxide sheet. These particles had interesting magnetic properties including saturation magnetisations and coercivities of the order of 80 emu/g and 170 Oe respectively, making them suitable for a potential use as an exchange-pinned magnetic material.

  10. Magnetic materials. Properties and applications

    International Nuclear Information System (INIS)

    Bar'yakhtar, V.

    1998-01-01

    Main theoretical and experimental results of physics of magnetic materials have been stated. Special attention was paid to the problem of creation of magnetic materials for information recording and presentation. The results of fundamental researches have been considered for their effect on creation of magnetic materials with the properties required for production as well as the reverse effect of production financing on the development of fundamental investigations. The relations between the development of high technologies and the society requirements, financing volumes and the level of NIKOR. (author)

  11. Fe2.25W0.75O4/reduced graphene oxide nanocomposites for novel bifunctional photocatalyst: One-pot synthesis, magnetically recyclable and enhanced photocatalytic property

    International Nuclear Information System (INIS)

    Guo, Jinxue; Jiang, Bin; Zhang, Xiao; Zhou, Xiaoyu; Hou, Wanguo

    2013-01-01

    Fe 2.25 W 0.75 O 4 /reduced graphene oxide (RGO) composites were prepared for application of novel bifunctional photocatalyst via simple one-pot hydrothermal method, employing graphene oxide (GO), Na 2 WO 4 , FeSO 4 and sodium dodecyl benzene sulfonate (SDBS) as the precursors. Transmission electron microscope (TEM) results indicate that the well-dispersed Fe 2.25 W 0.75 O 4 nanoparticles were deposited on the surface of RGO sheets homogeneously. Magnetic characterization reveals that Fe 2.25 W 0.75 O 4 and Fe 2.25 W 0.75 O 4 /RGO show ferromagnetic behaviors. So this novel bifunctional photocatalyst could achieve magnetic separation and collection with the aid of external magnet. The composites exhibit enhanced photocatalytic performance on degradation of methyl orange (MO) compared with pure Fe 2.25 W 0.75 O 4 under low-power ultraviolet light irradiation due to the introduction of RGO. Moreover, this hybrid catalyst possesses long-term excellent photocatalytic performance due to its good thermal stability. This bifunctional photocatalyst, which combines magnetic property and excellent photocatalytic activity, would be a perfect candidate in applications of catalytic elimination of environmental pollutants and other areas. - Graphical abstract: Magnetically recyclable Fe 2.25 W 0.75 O 4 /reduced graphene oxide nanocomposites with enhanced photocatalytic property Display Omitted - Highlights: ●Fe 2.25 W 0.75 O 4 growth, deposition and GO reduction occurred simultaneously. ●Composite possessed ferromagnetic and enhanced photocatalytic properties. ●Composite is utilized as a magnetically separable and high-efficient photocatalyst. ●Photocatalyst showed good photocatalytic and thermal stability during cyclic use

  12. Synthesis and characterization of robust magnetic carriers for bioprocess applications

    Energy Technology Data Exchange (ETDEWEB)

    Kopp, Willian, E-mail: willkopp@gmail.com [Federal University of São Carlos-UFSCar, Graduate Program in Chemical Engineering, Rodovia Washington Luiz, km 235, São Carlos, São Paulo 13565-905 (Brazil); Silva, Felipe A., E-mail: eq.felipe.silva@gmail.com [Federal University of São Carlos-UFSCar, Graduate Program in Chemical Engineering, Rodovia Washington Luiz, km 235, São Carlos, São Paulo 13565-905 (Brazil); Lima, Lionete N., E-mail: lionetenunes@yahoo.com.br [Federal University of São Carlos-UFSCar, Graduate Program in Chemical Engineering, Rodovia Washington Luiz, km 235, São Carlos, São Paulo 13565-905 (Brazil); Masunaga, Sueli H., E-mail: sueli.masunaga@gmail.com [Department of Physics, Montana State University-MSU, 173840, Bozeman, MT 59717-3840 (United States); Tardioli, Paulo W., E-mail: pwtardioli@ufscar.br [Department of Chemical Engineering, Federal University of São Carlos-UFSCar, Rodovia Washington Luiz, km 235, São Carlos, São Paulo 13565-905 (Brazil); Giordano, Roberto C., E-mail: roberto@ufscar.br [Department of Chemical Engineering, Federal University of São Carlos-UFSCar, Rodovia Washington Luiz, km 235, São Carlos, São Paulo 13565-905 (Brazil); Araújo-Moreira, Fernando M., E-mail: faraujo@df.ufscar.br [Department of Physics, Federal University of São Carlos-UFSCar, Rodovia Washington Luiz, km 235, São Carlos, São Paulo 13565-905 (Brazil); and others

    2015-03-15

    Highlights: • Silica magnetic microparticles were synthesized for applications in bioprocesses. • The process to produce magnetic microparticles is inexpensive and easily scalable. • Microparticles with very high saturation magnetization were obtained. • The structure of the silica magnetic microparticles could be controlled. - Abstract: Magnetic carriers are an effective option to withdraw selected target molecules from complex mixtures or to immobilize enzymes. This paper describes the synthesis of robust silica magnetic microparticles (SMMps), particularly designed for applications in bioprocesses. SMMps were synthesized in a micro-emulsion, using sodium silicate as the silica source and superparamagnetic iron oxide nanoparticles as the magnetic core. Thermally resistant particles, with high and accessible surface area, narrow particle size distribution, high saturation magnetization, and with superparamagnetic properties were obtained. Several reaction conditions were tested, yielding materials with saturation magnetization between 45 and 63 emu g{sup −1}, particle size between 2 and 200 μm and average diameter between 11.2 and 15.9 μm, surface area between 49 and 103 m{sup 2} g{sup −1} and pore diameter between 2 and 60 nm. The performance of SMMps in a bioprocess was evaluated by the immobilization of Pseudomonas fluorescens lipase on to octyl modified SMMp, the biocatalyst obtained was used in the production of butyl butyrate with good results.

  13. Connection between microstructure and magnetic properties of soft magnetic materials

    International Nuclear Information System (INIS)

    Bertotti, G.

    2008-01-01

    The magnetic behavior of soft magnetic materials is discussed with some emphasis on the connection between macroscopic properties and underlying micromagnetic energy aspects. It is shown that important conceptual gaps still exist in the interpretation of macroscopic magnetic properties in terms of the micromagnetic formulation. Different aspects of hysteresis modeling, power loss prediction and magnetic non-destructive evaluation are discussed in this perspective

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-01-01

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

  15. Synthesis of pure iron magnetic nanoparticles in large quantity

    International Nuclear Information System (INIS)

    Tiwary, C S; Kashyap, S; Chattopadhyay, K; Biswas, K

    2013-01-01

    Free nanoparticles of iron (Fe) and their colloids with high saturation magnetization are in demand for medical and microfluidic applications. However, the oxide layer that forms during processing has made such synthesis a formidable challenge. Lowering the synthesis temperature decreases rate of oxidation and hence provides a new way of producing pure metallic nanoparticles prone to oxidation in bulk amount (large quantity). In this paper we have proposed a methodology that is designed with the knowledge of thermodynamic imperatives of oxidation to obtain almost oxygen-free iron nanoparticles, with or without any organic capping by controlled milling at low temperatures in a specially designed high-energy ball mill with the possibility of bulk production. The particles can be ultrasonicated to produce colloids and can be bio-capped to produce transparent solution. The magnetic properties of these nanoparticles confirm their superiority for possible biomedical and other applications. (paper)

  16. Synthesis and magnetic properties of layered MnPSxSe3-x (0 < x < 3) and corresponding intercalation compounds of 2,2'-bipyridine

    International Nuclear Information System (INIS)

    Yan, Xiaobing; Chen, Xingguo; Qin, Jingui

    2011-01-01

    Graphical abstract: A series of new layered MnPS x Se 3-x (0 x Se 3-x exhibited antiferromagnetism similar to MnPS 3 or MnPSe 3 , but the intercalation of 2,2'-bipyridine can dramatically change the properties of MnPS x Se 3-x slab. Research highlights: → A series of new MnPS x Se 3-x are designed and synthesized for the first time and their layered structure has been determined. → The intercalation chemistry has been initially studied via the intercalation of 2,2'-bipyridine with MnPS x Se 3-x . → The magnetic properties of the series MnPS x Se 3-x and the corresponding intercalation compounds of 2,2'-bipydine have been studied. And the relationship between the structure and the magnetic propertied has been primarily explored. -- Abstract: In this work, we synthesize a series of new MnPS x Se 3-x (0 1-y PS x Se 3-x (bipy) 4y , x = 1.2, 1.8 and 2.4) via the intercalation of 2,2'-bipyridine with MnPS x Se 3-x . XRD results confirm that MnPS x Se 3-x compounds show the layered structure and can be regarded as the solid solution of MnPS 3 and MnPSe 3 . Magnetic measurements indicate that MnPS x Se 3-x compounds exhibit paramagnetism with negative Weiss constant in the paramagnetic temperature region, and an antiferromagnetic phase transition occurs at the Neel temperature. It is found that the magnetic properties of MnPS x Se 3-x slab are dramatically changed after the intercalation of 2,2'-bipyridine, which is close related to the relative ratio of S and Se atom as well as the intralayered Mn 2+ vacancies of MnPS x Se 3-x slab.

  17. Facile microwave synthesis of uniform magnetic nanoparticles with minimal sample processing

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, Thomas, E-mail: tom.schneider@ubc.ca [Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, V6T 1Z3 Canada (Canada); Löwa, Anna; Karagiozov, Stoyan [Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, V6T 1Z3 Canada (Canada); Sprenger, Lisa [Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, V6T 1Z3 Canada (Canada); TU Dresden, Chair of Magnetofluiddynamics, Measuring and Automation Technology, Dresden, 01062 Germany (Germany); Gutiérrez, Lucía [Instituto Universitario de Nanociencia de Aragón (INA), University of Zaragoza, Zaragoza, 50018 Spain (Spain); Esposito, Tullio; Marten, Gernot; Saatchi, Katayoun [Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, V6T 1Z3 Canada (Canada); Häfeli, Urs O., E-mail: urs.hafeli@ubc.ca [Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, V6T 1Z3 Canada (Canada)

    2017-01-01

    We present a simple and rapid method for the synthesis of small magnetic nanoparticles (diameters in the order of 5–20 nm) and narrow size distributions (CV's of 20–40%). The magnetite nanoparticles were synthesized in green solvents within minutes and the saturation magnetization of the particles was tunable by changes in the reaction conditions. We show that this particle synthesis method requires minimal processing steps and we present the successful coating of the particles with reactive bisphosphonates after synthesis without washing or centrifugation. We found minimal batch-to-batch variability and show the scalability of the particle synthesis method. We present a full characterization of the particle properties and believe that this synthesis method holds great promise for facile and rapid generation of magnetic nanoparticles with defined surface coatings for magnetic targeting applications. - Highlights: ●Rapid and facile synthesis of magnetic nanoparticles. ●Microwave synthesis in green solvent. ●Magnetite MNPs with small sizes and high saturation magnetization. ●Tunable particle properties depending on heating duration. ●Scalable MNP synthesis.

  18. Synthesis, characterization and magnetic property of maghemite (γ-Fe{sub 2}O{sub 3}) nanoparticles and their protective coating with pepsin for bio-functionalization

    Energy Technology Data Exchange (ETDEWEB)

    Bandhu, A.; Sutradhar, S.; Mukherjee, S. [Solid State Research Laboratory, Department of Physics, Burdwan University, Burdwan 713104, West Bengal (India); Greneche, J.M. [Laboratoire de Physique de l’Etat Condensé – UMR CNRS 6087, Université du Maine, 72085, Le Mans Cedex 9 (France); Chakrabarti, P.K., E-mail: pabitra_c@hotmail.com [Solid State Research Laboratory, Department of Physics, Burdwan University, Burdwan 713104, West Bengal (India)

    2015-10-15

    Highlights: • Maghemite nanoparticles were prepared by a modified co-precipitation method. • Nanoparticles were then successfully coated with pepsin for bio-functionlization. • XRD and Mössbauer spectra confirmed the maghemite phase of the nanoparticles. • Magnetic data were analysed to evaluate particle size, anisotropy etc. - Abstract: Maghemite nanoparticles (γ-Fe{sub 2}O{sub 3}) are prepared by co-precipitation method. To obtain bio-functionalized magnetic nanoparticles for magnetically controlled drug delivery, the prepared nanoparticles are successfully coated with pepsin, a bio-compatible polymer and digestive enzyme. Crystallographic phase of the nanoparticles is confirmed by X-ray diffractograms (XRD), high resolution transmission electron microscopy (HRTEM) and {sup 57}Fe Mössbauer spectrometry. The average size of nanoparticles/nanocrystallites is estimated from the (3 1 1) peak of the XRD pattern using Debye–Scherrer formula. Results of HRTEM of coated and bare samples are in good agreement with those extracted from the XRD analysis. The dynamic magnetic properties are observed and different quantities viz., coercive field, magnetization, remanence, hysteresis losses etc., are estimated, which confirmed the presence of superparamagnetic relaxation of nanoparticles. Mössbauer spectra of the samples recorded at both 300 and 77 K, confirmed that the majority of particles are maghemite together with a very small fraction of magnetite nanoparticles.

  19. Synthesis, characterization and magnetic property of maghemite (γ-Fe2O3) nanoparticles and their protective coating with pepsin for bio-functionalization

    International Nuclear Information System (INIS)

    Bandhu, A.; Sutradhar, S.; Mukherjee, S.; Greneche, J.M.; Chakrabarti, P.K.

    2015-01-01

    Highlights: • Maghemite nanoparticles were prepared by a modified co-precipitation method. • Nanoparticles were then successfully coated with pepsin for bio-functionlization. • XRD and Mössbauer spectra confirmed the maghemite phase of the nanoparticles. • Magnetic data were analysed to evaluate particle size, anisotropy etc. - Abstract: Maghemite nanoparticles (γ-Fe 2 O 3 ) are prepared by co-precipitation method. To obtain bio-functionalized magnetic nanoparticles for magnetically controlled drug delivery, the prepared nanoparticles are successfully coated with pepsin, a bio-compatible polymer and digestive enzyme. Crystallographic phase of the nanoparticles is confirmed by X-ray diffractograms (XRD), high resolution transmission electron microscopy (HRTEM) and 57 Fe Mössbauer spectrometry. The average size of nanoparticles/nanocrystallites is estimated from the (3 1 1) peak of the XRD pattern using Debye–Scherrer formula. Results of HRTEM of coated and bare samples are in good agreement with those extracted from the XRD analysis. The dynamic magnetic properties are observed and different quantities viz., coercive field, magnetization, remanence, hysteresis losses etc., are estimated, which confirmed the presence of superparamagnetic relaxation of nanoparticles. Mössbauer spectra of the samples recorded at both 300 and 77 K, confirmed that the majority of particles are maghemite together with a very small fraction of magnetite nanoparticles

  20. Synthesis and atomic scale characterization of Er2O3 nanoparticles: enhancement of magnetic properties and changes in the local structure

    Science.gov (United States)

    Corrêa, Eduardo L.; Bosch-Santos, Brianna; Freitas, Rafael S.; Potiens, Maria da Penha A.; Saiki, Mitiko; Carbonari, Artur W.

    2018-05-01

    In the investigation reported in this paper a modified thermal decomposition method was developed to produce very small Er2O3 nanoparticles (NPs). Particles structure, shape and size were characterized by x-ray diffraction and transmission electron microscopy which showed that the synthesis by thermal decomposition under O2 atmosphere produced very small and monodisperse NPs, allowing the investigation of finite-size and surface effects. Results of magnetization measurements showed that the smallest particles present the highest values of susceptibility that decrease as particle size increases. Specific heat measurements indicate that the sample with the smallest NPs (diameter ∼5 nm) has a Néel temperature of 0.54 K. The local structure of particles was investigated by measurements of hyperfine interactions with perturbed angular correlation spectroscopy using 111Cd as probe nuclei replacing the cationic sites. Results showed that the relative population of sites 8b increases in both the core and surface layer of particles.

  1. Gelatine-assisted synthesis of magnetite nanoparticles for magnetic hyperthermia

    Energy Technology Data Exchange (ETDEWEB)

    Alves, André F.; Mendo, Sofia G. [Universidade de Lisboa, Centro de Química e Bioquímica, Faculdade de Ciências (Portugal); Ferreira, Liliana P. [Universidade de Lisboa, Biosystems and Integrative Sciences Institute, Faculdade de Ciências (Portugal); Mendonça, Maria Helena [Universidade de Lisboa, Centro de Química e Bioquímica, Faculdade de Ciências (Portugal); Ferreira, Paula [University of Aveiro, Department of Materials and Ceramic Engineering, CICECO - Aveiro Institute of Materials (Portugal); Godinho, Margarida; Cruz, Maria Margarida [Universidade de Lisboa, Biosystems and Integrative Sciences Institute, Faculdade de Ciências (Portugal); Carvalho, Maria Deus, E-mail: mdcarvalho@ciencias.ulisboa.pt [Universidade de Lisboa, Centro de Química e Bioquímica, Faculdade de Ciências (Portugal)

    2016-01-15

    Magnetite nanoparticles were synthesized by the co-precipitation method exploring the use of gelatine and agar as additives. For comparison, magnetite nanoparticles were also prepared by standard co-precipitation, by co-precipitation with the addition of a surfactant (sodium dodecyl sulphate) and by the thermal decomposition method. The structure and morphology of the synthesized nanoparticles were investigated by powder X-ray diffraction and transmission electron microscopy. Their magnetic properties were studied by SQUID magnetometry and {sup 57}Fe Mössbauer spectroscopy. The nanoparticles potential for applications in magnetic hyperthermia was evaluated through heating efficiency under alternating magnetic field. The results show that all synthesis methods produce Fe{sub 3−x}O{sub 4} nanoparticles with similar sizes. The nanoparticles synthesized in the gelatine medium display the narrowest particle size distribution, the lowest oxidation degree, one of the highest saturation magnetization values and the best hyperthermia efficiency, proving that this gelatine-assisted synthesis is an efficient, environmental friendly, and low-cost method to produce magnetite nanoparticles. Graphical Abstract: A new gelatine-assisted method is an efficient and low-cost way to synthesize magnetite nanoparticles with enhanced magnetic hyperthermia.

  2. Ammonia synthesis using magnetic induction method (MIM)

    Science.gov (United States)

    Puspitasari, P.; Razak, J. Abd; Yahya, N.

    2012-09-01

    The most challenging issues for ammonia synthesis is to get the high yield. New approach of ammonia synthesis by using Magnetic Induction Method (MIM) and the Helmholtz Coils has been proposed. The ammonia detection was done by using Kjeldahl Method and FTIR. The system was designed by using Autocad software. The magnetic field of MIM was vary from 100mT-200mT and the magnetic field for the Helmholtz coils was 14mT. The FTIR result shows that ammonia has been successfully formed at stretching peaks 1097,1119,1162,1236, 1377, and 1464 cm-1. UV-VIS result shows the ammonia bond at 195nm of wavelength. The ammonia yield was increase to 244.72μmole/g.h by using the MIM and six pairs of Helmholtz coils. Therefore this new method will be a new promising method to achieve the high yield ammonia at ambient condition (at 25δC and 1atm), under the Magnetic Induction Method (MIM).

  3. Electrical and Magnetic Properties of Polyvinyl Alcohol-Cobalt ...

    Indian Academy of Sciences (India)

    7

    synthesis methods of shape, size, magnetic properties of cobalt ferrite ... substance was then ground into a fine powder and calcined at 600oC for 10 hours and .... From the particles distribution pattern of CFO nanoparticles in Figure 2(a), it is.

  4. Hydrothermal synthesis of Ag@TiO2–Fe3O4 nanocomposites using sonochemically activated precursors: magnetic, photocatalytic and antibacterial properties

    International Nuclear Information System (INIS)

    Bokare, Anuja; Singh, Hema; Nair, Roopa; Sabharwal, Sushma; Athawale, Anjali A; Pai, Mrinal

    2014-01-01

    Fe 3 O 4 –TiO 2 nanocomposites have been synthesized by hydrothermal method using sonochemically activated precursors. X-ray diffraction analysis of the samples reveals the formation of pure phase composites. The optical properties of the composites are superior to TiO 2 as noted from the red shift in the diffused reflectance spectra of the composites. The presence of nanocubes of Fe 3 O 4 , nanospheres of TiO 2 and heterojunctions of the two in the composite samples have been observed in transmission electron micrographs. The magnetic properties of the samples were determined with the help of vibrating sample magnetometry (VSM) and magnetic force microscopy (MFM). The photocatalytic activity of the samples was investigated in terms of degradation of methyl orange (MO) dye. The composites could be easily separated from the reaction mixture after photocatalysis due to their magnetic behaviour. However, the photocatalytic activity of the composites was observed to be lower compared to bare TiO 2 . The composite (15% Fe 3 O 4 –TiO 2 ) when modified by coating it with Ag showed enhanced photocatalytic activity. Further, the antibacterial activities of the samples were also examined using E. coli as a model organism. Positive results were obtained only for the Ag coated composite with lower MIC (minimum inhibition concentration) values. (paper)

  5. Hydrothermal synthesis of Ag@TiO2-Fe3O4 nanocomposites using sonochemically activated precursors: magnetic, photocatalytic and antibacterial properties

    Science.gov (United States)

    Bokare, Anuja; Singh, Hema; Pai, Mrinal; Nair, Roopa; Sabharwal, Sushma; Athawale, Anjali A.

    2014-12-01

    Fe3O4-TiO2 nanocomposites have been synthesized by hydrothermal method using sonochemically activated precursors. X-ray diffraction analysis of the samples reveals the formation of pure phase composites. The optical properties of the composites are superior to TiO2 as noted from the red shift in the diffused reflectance spectra of the composites. The presence of nanocubes of Fe3O4, nanospheres of TiO2 and heterojunctions of the two in the composite samples have been observed in transmission electron micrographs. The magnetic properties of the samples were determined with the help of vibrating sample magnetometry (VSM) and magnetic force microscopy (MFM). The photocatalytic activity of the samples was investigated in terms of degradation of methyl orange (MO) dye. The composites could be easily separated from the reaction mixture after photocatalysis due to their magnetic behaviour. However, the photocatalytic activity of the composites was observed to be lower compared to bare TiO2. The composite (15% Fe3O4-TiO2) when modified by coating it with Ag showed enhanced photocatalytic activity. Further, the antibacterial activities of the samples were also examined using E. coli as a model organism. Positive results were obtained only for the Ag coated composite with lower MIC (minimum inhibition concentration) values.

  6. Synthesis of {alpha}-Fe{sub 2}O{sub 3} nanobelts and nanoflakes by thermal oxidation and study to their magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Su Xinghua [School of Materials Science and Engineering, Chang' an University, Xi' an 710061 (China); Yu Chengshou [Department of Materials Science and Engineering, Lanzhou University, Lanzhou 730000 (China); Qiang Chengwen, E-mail: qiangchw04@gmail.com [Department of Materials Science and Engineering, Lanzhou University, Lanzhou 730000 (China); Institute of Modern Physics, Chinese Academy of Science, Lanzhou 730000 (China)

    2011-08-15

    {alpha}-Fe{sub 2}O{sub 3} nanobelts and nanoflakes have been successfully synthesized by oxidation of iron-coated ITO glass in air. The X-ray diffraction, Raman spectrum and scanning electron microscopy are carried out to characterize the nanobelts and nanoflakes. The formation mechanism has been presented. Significantly, the magnetic investigations show that the magnetic properties are strongly shape-dependent. The magnetization measurements of belt-like and flake-like {alpha}-Fe{sub 2}O{sub 3} in perpendicular exhibit ferromagnetic feature with the coercivity (H{sub c}) and saturation magnetization (M{sub s}) of 334.5 Oe and 1.35 emu/g, 239.5 Oe and 0.12 emu/g, respectively. For the parallel, belt-like and flake-like {alpha}-Fe{sub 2}O{sub 3} also exhibit ferromagnetic feature with the H{sub c} and M{sub s} of 205.5 Oe and 1.44 emu/g, 159.6 Oe and 0.15 emu/g, respectively.

  7. Synthesis, magnetic properties and electronic structure of the S  =  ½ uniform spin chain system InCuPO5

    Science.gov (United States)

    Koteswararao, B.; Hazra, Binoy K.; Rout, Dibyata; Srinivasarao, P. V.; Srinath, S.; Panda, S. K.

    2017-07-01

    We have studied the structural and magnetic properties and electronic structure of the compound InCuPO5 synthesized by a solid state reaction method. The structure of InCuPO5 comprises S  =  ½ uniform spin chains formed by corner-shared CuO4 units. Magnetic susceptibility (χ(T)) data show a broad maximum at about 65 K, a characteristic feature of one-dimensional (1D) magnetism. The χ(T) data are fitted to the coupled S  =  ½ Heisenberg antiferromagnetic (HAFM) uniform chain model that gives the intra-chain coupling (J/k B) between nearest-neighbor Cu2+ ions as  -100 K and the ratio of inter-chain to intra-chain coupling (J‧/J) as about 0.07. The exchange couplings estimated from the magnetic data analysis are in good agreement with the values computed from the electronic structure calculations based on the density functional theory  +  Hubbard U (DFT  +  U) approach. The combination of theoretical and experimental analysis confirms that InCuPO5 is a candidate material for weakly coupled S  = ½ uniform chains. A detailed theoretical analysis of the electronic structure further reveals that the system is insulating with a gap of 2.4 eV and a local moment of 0.70 µ B/Cu.

  8. In Situ Studies and Magnetic Properties of the Cmcm Polymorph of LiCoPO4 with a Hierarchical Dumbbell-Like Morphology Synthesized by Easy Single-Step Polyol Synthesis

    Directory of Open Access Journals (Sweden)

    Carlos Alarcón-Suesca

    2016-11-01

    Full Text Available LiCoPO4 (LCP exists in three different structural modifications: LCP-Pnma (olivine structure, LCP-Pn21a (KNiPO4 structure type, and LCP-Cmcm (Na2CrO4 structure type. The synthesis of the LCP-Cmcm polymorph has been reported via high pressure/temperature solid-state methods and by microwave-assisted solvothermal synthesis. Phase transitions from both LCP-Pn21a and LCP-Cmcm to LCP-Pnma upon heating indicates a metastable behavior. However, a precise study of the structural changes during the heating process and the magnetic properties of LCP-Cmcm are hitherto unknown. Herein, we present the synthesis and characterization of LCP-Cmcm via a rapid and facile soft-chemistry approach using two different kinetically controlled pathways, solvothermal and polyol syntheses, both of which only require relatively low temperatures (~200 °C. Additionally, by polyol, method a dumbbell-like morphology is obtained without the use of any additional surfactant or template. A temperature-dependent in situ powder XRD shows a transition from LCP-Cmcm at room temperature to LCP-Pnma and finally to LCP-Pn21a at 575 and 725 °C, respectively. In addition to that, the determination of the magnetic susceptibility as a function of temperature indicates a long-range antiferromagnetic order below TN = 11 K at 10 kOe and 9.1 K at 25 kOe. The magnetization curves suggests the presence of a metamagnetic transition.

  9. 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.

  10. Synthesis, characterization and magnetic properties of NiFe{sub 2−x}Ce{sub x}O{sub 4} nanoribbons by electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jianan; Jing, Panpan; Zhang, Xinlei; Cao, Derang; Wei, Jinwu; Pan, Lining [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Liu, Zhenlin [Analysis and researching center of Gansu province, Lanzhou 730000 (China); Wang, Jianbo [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Key Laboratory for Special Function Materials and Structural Design of the Ministry of the Education, Lanzhou University, Lanzhou 730000 (China); Liu, Qingfang, E-mail: liuqf@lzu.edu.cn [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China)

    2017-03-01

    NiFe{sub 2−x}Ce{sub x}O{sub 4} (x = 0–0.03) nanoribbons have been successfully fabricated using electrospinning technique and followed by calcining in air at 500 °C. The crystalline, morphologies and compositions of NiFe{sub 2−x}Ce{sub x}O{sub 4} nanoribbons are characterized by X-ray diffraction, selected area electron diffraction, transmission electron microscope, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy (EDX). The results show that the components, mean crystallite sizes and morphologies change along with the content of Ce{sup 3+}. A formation mechanism of NiFe{sub 2-x}Ce{sub x}O{sub 4} nanoribbons is proposed. The magnetic hysteresis loops of NiFe{sub 2−x}Ce{sub x}O{sub 4} nanoribbons reveals that the coercivity changes from 165 Oe to 64 Oe and saturation magnetizations change from 40.97 emu/g to 25.05 emu/g at room temperature. Morevover, the Mössbauer spectra of {sup 57}Fe in NiFe{sub 2−x}Ce{sub x}O{sub 4} nanoribbons is discussed in detail. It is believed that this work will play important role in magnetic application with the advantage of excellent magnetic properties, efficient functionalization and relatively low cost. - Highlights: • The NiFe{sub 2−x}Ce{sub x}O{sub 4} nanoribbons have been fabricated using electrospinning technique. • Ce{sup 3+} ions occupy B sites by replacing Fe{sup 3+} ions. • The coercivity changes from 165 Oe to 64 Oe. • The saturation magnetizations change from 40.97 emu/g to 25.05 emu/g.

  11. Synthesis of flexible magnetic nanohybrid based on bacterial cellulose under ultrasonic irradiation

    International Nuclear Information System (INIS)

    Zheng, Yi; Yang, Jingxuan; Zheng, Weili; Wang, Xiao; Xiang, Cao; Tang, Lian; Zhang, Wen; Chen, Shiyan; Wang, Huaping

    2013-01-01

    Flexible magnetic membrane based on bacterial cellulose (BC) was successfully prepared by in-situ synthesis of the Fe 3 O 4 nanoparticles under different conditions and its properties were characterized. The results demonstrated that the Fe 3 O 4 nanoparticles coated with PEG were well homogeneously dispersed in the BC matrix under ultrasonic irradiation with the saturation magnetization of 40.58 emu/g. Besides that, the membranes exhibited the striking flexibility and mechanical properties. This study provided a green and facile method to inhibit magnetic nanoparticle aggregation without compromising the mechanical properties of the nanocomposites. Magnetically responsive BC membrane would have potential applications in electronic actuators, information storage, electromagnetic shielding coating and anti-counterfeit. - Highlights: ► Flexible magnetic film is prepared by in situ synthesis on bacterial cellulose. ► Ultrasound and PEG are used together to inhibit the nanoparticle aggregation. ► The magnetic membrane demonstrates the great superparamagnetic behavior

  12. Green urea synthesis catalyzed by hematite nanowires in magnetic field

    International Nuclear Information System (INIS)

    Yahya, Noorhana; Qureshi, Saima; Rehman, Zia ur; Alqasem, Bilal; Fai Kait, Chong

    2017-01-01

    The catalytic activity of hematite (α-Fe 2 O 3 ) nanowires under the influence of magnetic field on urea synthesis is considered green. The adsorption and subsequent dissociative reaction of hydrogen, nitrogen and carbon dioxide gases on the α-Fe 2 O 3 (111) nanowires were investigated using the density functional theory (DFT) method. The average adsorption energy is −4.12 kcal/mole at different sites. The adsorption of gases resulted in a difference in density and net spin of electrons from 68 to 120 and 0–21 respectively. In addition, it induces magnetic moment value of 36.33 µB, which confirms the enhanced magnetic behaviour of hematite. α-Fe 2 O 3 nanowires (NWs) synthesized by heating iron wire in a box furnace at (750−800) °C and as synthesized α-Fe 2 O 3 nanoparticles (NPs) were received to use as a catalyst in the magnetic reaction of urea synthesis. X-ray Diffractometer (XRD) confirms the peaks of rhombohedral structure of α-Fe 2 O 3 and Raman spectrum analyses confirms the α-Fe 2 O 3 peaks at 410 cm −1 , 500 cm −1 and 616 cm −1 . The needle-like shape of hematite nanowires with length ranging from 16–25) μm and diameter from 74 to 145 nm confirmed by Field emission scanning electron microscopy (FESEM). The magnetic properties of the nanowires exhibited different levels of saturation magnetization, for α-Fe 2 O 3 perpendicularly aligned direction (13.18 emu/g) and random direction (10.73 emu/g). Urea synthesis was done under magnetic field ranges from 0.0 to 2.5 T. The activation energy of α-Fe 2 O 3 NWs for urea production is lower than NPs in the range of 0–1 T, whereas it is reversed for higher magnetic induction values. Fourier transform infrared spectroscopy (FTIR) confirmed the formation of urea at the peaks of 1690–1600 cm −1 . This green urea employing magnetically induced method could be a contender to the Haber-Bosch process currently used by the current industry which utilizes high temperature and high pressure

  13. Bi-Component Nanostructured Arrays of Co Dots Embedded in Ni80Fe20 Antidot Matrix: Synthesis by Self-Assembling of Polystyrene Nanospheres and Magnetic Properties.

    Science.gov (United States)

    Coïsson, Marco; Celegato, Federica; Barrera, Gabriele; Conta, Gianluca; Magni, Alessandro; Tiberto, Paola

    2017-08-23

    A bi-component nanostructured system composed by a Co dot array embedded in a Ni 80 Fe 20 antidot matrix has been prepared by means of the self-assembling polystyrene nanospheres lithography technique. Reference samples constituted by the sole Co dots or Ni 80 Fe 20 antidots have also been prepared, in order to compare their properties with those of the bi-component material. The coupling between the two ferromagnetic elements has been studied by means of magnetic and magneto-transport measurements. The Ni 80 Fe 20 matrix turned out to affect the vortex nucleation field of the Co dots, which in turn modifies the magneto-resistance behaviour of the system and its spinwave properties.

  14. Synthesis and properties of bimetallic aluminium alkoxides

    International Nuclear Information System (INIS)

    Vyshinskaya, K.I.; Vasil'ev, G.A.; Vishnyakova, T.A.

    1997-01-01

    A single stage method of aluminium bimetallic alkoxide synthesis, which consists in activated aluminium reaction with metal salts in the relevant alcohols, has been developed. Properties of the compounds prepared are described

  15. Photocatalytically active titanium dioxide nanopowders: Synthesis, photoactivity and magnetic separation

    International Nuclear Information System (INIS)

    Nikkanen, J-P; Heinonen, S; Saarivirta, E Huttunen; Honkanen, M; Levänen, E

    2013-01-01

    Two approaches were used to obtain nanocrystalline titanium dioxide (TiO 2 ) photocatalyst powders. Firstly, low-temperature synthesis method and secondly liquid flame spraying. The structural properties of the produced powders were determined with X-ray diffraction, transmission electron microscopy and nitrogen adsorption tests. The photocatalytic properties of the powders were studied with methylene blue (MB) discoloration tests. After discolorations tests, TiO 2 was coagulated with magnetite particles using FeCl 3 ·6 H 2 O at a fixed pH value. Magnetic separation of coagulated TiO 2 and magnetite was carried out by a permanent magnet. The obtained results showed that the particle size of the powders synthesized at low-temperature was very small and the specific surface area high. The phase content of the powder was also shown to depend greatly on the acidity of the synthesis solution. Powder synthesized by liquid flame spraying was mixture of anatase and rutile phases with essentially larger particle size and lower specific surface area than those of low-temperature synthesized powders. The MB discoloration test showed that photocatalytic activity depends on the phase structure as well as the specific surface area of the synthesized TiO 2 powder. The magnetic separation of TiO 2 –magnetite coagulate from solution proved to be efficient around pH:8

  16. Morphology-controlled synthesis and novel microwave electromagnetic properties of hollow urchin-like chain Fe-doped MnO2 under 10 T high magnetic field

    International Nuclear Information System (INIS)

    Yuping, Duan; Jia, Zhang; Hui, Jing; Shunhua, Liu

    2011-01-01

    Fe-doped MnO 2 with a hollow sea urchin-like ball chain shape was first synthesized under a high magnetic field of 10 T. The formation mechanism was investigated and discussed in detail. The synthesized samples were characterized by XRD, SEM, TEM, EMPA, and vector network analysis. By doping MnO 2 with Fe, the relative complex permittivity of MnO 2 and its corresponding loss tangent clearly decreases, but its relative complex permeability and its corresponding loss tangent markedly increases. Moreover, the theoretically calculated values of reflection loss show that with increasing the Fe content, the as-prepared Fe-doped MnO 2 exhibits good microwave absorption capability. -- Graphical Abstract: Fe-doped MnO 2 with a hollow sea urchin-like ball chain shape was first synthesized in a high magnetic field of 10 T via a simple chemical process. Display Omitted Highlights: → Fe-doped MnO 2 with a hollow sea urchin-like ball chain shape was first synthesized. → We investigated formation mechanism and electromagnetic properties of the Fe-doped MnO 2 . → By doping MnO 2 with Fe, the electromagnetic properties are improved obviously.

  17. Three Cyanide-Bridged One-Dimensional Single Chain Co"I"I"I-Mn"I"I Complexes: Rational Design, Synthesis, Crystal Structures and Magnetic Properties

    International Nuclear Information System (INIS)

    Zhang, Daopeng; Zhao, Zengdian; Wang, Ping; Chen, Xia

    2012-01-01

    Two pyridinecarboxamide dicyanidecobalt(III) building blocks and two mononuclear seven-coordinated macrocycle manganese(II) compounds have been rationally selected to assemble cyanide-bridged heterobimetallic complexes, resulting in three cyanide-bridged Co"I"I"I-Mn"I"I complexes. Single X-ray diffraction analysis show that these complexes {[Mn(L"1)][Co(bpb)]}ClO_4·CH_3OH·0.5H_2O (1), {[Mn(L"2)][Co(bpb)]}ClO_4·0.5CH_3OH (2) and {[Mn(L"1)][Cobpmb]}ClO_4·H_2O (3) (L"1 = 3,6-diazaoctane-1,8-diamine, L"2 = 3,6-dioxaoctano-1,8- diamine: bpb"2"- = 1,2-bis(pyridine-2-carboxamido)benzenate, bpmb"2"- = 1,2-bis(pyridine-2-carboxamido)-4- methyl-benzenate) all present predictable one-dimensional single chain structures. The molecular structures of these one-dimensional complexes consists of alternating units of [Mn(L)]"2"+ (L = L"1 or L"2) and [Co(L')(CN)_2]"- (L' = bpb"2"-, or bpmb"2"-), forming a cyanide-bridged cationic polymeric chain with free ClO_4"- as the balance anion. The coordination geometry of manganese(II) ion in the three one-dimensional complexes is a slightly distorted pentagonal-bipyrimidal with two cyanide nitrogen atoms at the trans positions and N_5 or N_3O_2 coordinating mode at the equatorial plane from ligand L"1 or L"2. Investigation over magnetic properties of these complexes reveals that the very weak magnetic coupling between neighboring Mn(II) ions connected by the diamagnetic dicyanidecobalt(III) building block. A best-fit to the magnetic susceptibility of complex 1 leads to the magnetic coupling constants J = .0.084(3) cm"-"1

  18. Synthesis of α-Fe2O3 and Fe-Mn Oxide Foams with Highly Tunable Magnetic Properties by the Replication Method from Polyurethane Templates

    Directory of Open Access Journals (Sweden)

    Yuping Feng

    2018-02-01

    Full Text Available Open cell foams consisting of Fe and Fe-Mn oxides are prepared from metallic Fe and Mn powder precursors by the replication method using porous polyurethane (PU templates. First, reticulated PU templates are coated by slurry impregnation. The templates are then thermally removed at 260 °C and the debinded powders are sintered at 1000 °C under N2 atmosphere. The morphology, structure, and magnetic properties are studied by scanning electron microscopy, X-ray diffraction and vibrating sample magnetometry, respectively. The obtained Fe and Fe-Mn oxide foams possess both high surface area and homogeneous open-cell structure. Hematite (α-Fe2O3 foams are obtained from the metallic iron slurry independently of the N2 flow. In contrast, the microstructure of the FeMn-based oxide foams can be tailored by adjusting the N2 flow. While the main phases for a N2 flow rate of 180 L/h are α-Fe2O3 and FeMnO3, the predominant phase for high N2 flow rates (e.g., 650 L/h is Fe2MnO4. Accordingly, a linear magnetization versus field behavior is observed for the hematite foams, while clear hysteresis loops are obtained for the Fe2MnO4 foams. Actually, the saturation magnetization of the foams containing Mn increases from 5 emu/g to 52 emu/g when the N2 flow rate (i.e., the amount of Fe2MnO4 is increased. The obtained foams are appealing for a wide range of applications, such as electromagnetic absorbers, catalysts supports, thermal and acoustic insulation systems or wirelessly magnetically-guided porous objects in fluids.

  19. Synthesis of α-Fe₂O₃ and Fe-Mn Oxide Foams with Highly Tunable Magnetic Properties by the Replication Method from Polyurethane Templates.

    Science.gov (United States)

    Feng, Yuping; Fornell, Jordina; Zhang, Huiyan; Solsona, Pau; Barό, Maria Dolors; Suriñach, Santiago; Pellicer, Eva; Sort, Jordi

    2018-02-11

    Open cell foams consisting of Fe and Fe-Mn oxides are prepared from metallic Fe and Mn powder precursors by the replication method using porous polyurethane (PU) templates. First, reticulated PU templates are coated by slurry impregnation. The templates are then thermally removed at 260 °C and the debinded powders are sintered at 1000 °C under N₂ atmosphere. The morphology, structure, and magnetic properties are studied by scanning electron microscopy, X-ray diffraction and vibrating sample magnetometry, respectively. The obtained Fe and Fe-Mn oxide foams possess both high surface area and homogeneous open-cell structure. Hematite (α-Fe₂O₃) foams are obtained from the metallic iron slurry independently of the N₂ flow. In contrast, the microstructure of the FeMn-based oxide foams can be tailored by adjusting the N₂ flow. While the main phases for a N₂ flow rate of 180 L/h are α-Fe₂O₃ and FeMnO₃, the predominant phase for high N₂ flow rates (e.g., 650 L/h) is Fe₂MnO₄. Accordingly, a linear magnetization versus field behavior is observed for the hematite foams, while clear hysteresis loops are obtained for the Fe₂MnO₄ foams. Actually, the saturation magnetization of the foams containing Mn increases from 5 emu/g to 52 emu/g when the N₂ flow rate (i.e., the amount of Fe₂MnO₄) is increased. The obtained foams are appealing for a wide range of applications, such as electromagnetic absorbers, catalysts supports, thermal and acoustic insulation systems or wirelessly magnetically-guided porous objects in fluids.

  20. Synthesis of α-Fe2O3 and Fe-Mn Oxide Foams with Highly Tunable Magnetic Properties by the Replication Method from Polyurethane Templates

    Science.gov (United States)

    Feng, Yuping; Fornell, Jordina; Zhang, Huiyan; Solsona, Pau; Barό, Maria Dolors; Suriñach, Santiago; Sort, Jordi

    2018-01-01

    Open cell foams consisting of Fe and Fe-Mn oxides are prepared from metallic Fe and Mn powder precursors by the replication method using porous polyurethane (PU) templates. First, reticulated PU templates are coated by slurry impregnation. The templates are then thermally removed at 260 °C and the debinded powders are sintered at 1000 °C under N2 atmosphere. The morphology, structure, and magnetic properties are studied by scanning electron microscopy, X-ray diffraction and vibrating sample magnetometry, respectively. The obtained Fe and Fe-Mn oxide foams possess both high surface area and homogeneous open-cell structure. Hematite (α-Fe2O3) foams are obtained from the metallic iron slurry independently of the N2 flow. In contrast, the microstructure of the FeMn-based oxide foams can be tailored by adjusting the N2 flow. While the main phases for a N2 flow rate of 180 L/h are α-Fe2O3 and FeMnO3, the predominant phase for high N2 flow rates (e.g., 650 L/h) is Fe2MnO4. Accordingly, a linear magnetization versus field behavior is observed for the hematite foams, while clear hysteresis loops are obtained for the Fe2MnO4 foams. Actually, the saturation magnetization of the foams containing Mn increases from 5 emu/g to 52 emu/g when the N2 flow rate (i.e., the amount of Fe2MnO4) is increased. The obtained foams are appealing for a wide range of applications, such as electromagnetic absorbers, catalysts supports, thermal and acoustic insulation systems or wirelessly magnetically-guided porous objects in fluids. PMID:29439450

  1. The magnetic properties of the hollow cylindrical ideal remanence magnet

    DEFF Research Database (Denmark)

    Bjørk, Rasmus

    2016-01-01

    We consider the magnetic properties of the hollow cylindrical ideal remanence magnet. This magnet is the cylindrical permanent magnet that generates a uniform field in the cylinder bore, using the least amount of magnetic energy to do so. The remanence distribution of this magnet is derived...... and the generated field is compared to that of a Halbach cylinder of equal dimensions. The ideal remanence magnet is shown in most cases to generate a significantly lower field than the equivalent Halbach cylinder, although the field is generated with higher efficiency. The most efficient Halbach cylinder is shown...... to generate a field exactly twice as large as the equivalent ideal remanence magnet....

  2. Synthesis, microstructure, and physical properties of metallic barcode nanowires

    Science.gov (United States)

    Park, Bum Chul; Kim, Young Keun

    2017-05-01

    With rapid progress in nanotechnology, nanostructured materials have come closer to our life. Single-component nanowires are actively investigated because of their novel properties, attributed to their nanoscale dimensions and adjustable aspect ratio, but their technical limitations cannot be resolved easily. Heterostructured nanomaterials gained attention as alternatives because they can improve the existing single-component structure or add new functions to it. Among them, barcode nanowires (BNWs), comprising at least two different functional segments, can perform multiple functions for use in biomedical sensors, information encoding and security, and catalysts. BNW applications require reliable response to the external field. Hence, researchers have been attempting to improve the reliability of synthesis and regulate the properties precisely. This article highlights the recent progress and prospects for the synthesis, properties, and applications of metallic BNWs with focus on the dependence of the magnetic, optical, and mechanical properties on material, composition, shape, and microstructure.

  3. Green urea synthesis catalyzed by hematite nanowires in magnetic field

    Science.gov (United States)

    Yahya, Noorhana; Qureshi, Saima; Rehman, Zia ur; Alqasem, Bilal; Fai Kait, Chong

    2017-04-01

    The catalytic activity of hematite (α-Fe2O3) nanowires under the influence of magnetic field on urea synthesis is considered green. The adsorption and subsequent dissociative reaction of hydrogen, nitrogen and carbon dioxide gases on the α-Fe2O3 (111) nanowires were investigated using the density functional theory (DFT) method. The average adsorption energy is -4.12 kcal/mole at different sites. The adsorption of gases resulted in a difference in density and net spin of electrons from 68 to 120 and 0-21 respectively. In addition, it induces magnetic moment value of 36.33 μB, which confirms the enhanced magnetic behaviour of hematite. α-Fe2O3 nanowires (NWs) synthesized by heating iron wire in a box furnace at (750-800) °C and as synthesized α-Fe2O3 nanoparticles (NPs) were received to use as a catalyst in the magnetic reaction of urea synthesis. X-ray Diffractometer (XRD) confirms the peaks of rhombohedral structure of α-Fe2O3 and Raman spectrum analyses confirms the α-Fe2O3 peaks at 410 cm-1, 500 cm-1 and 616 cm-1. The needle-like shape of hematite nanowires with length ranging from 16-25) μm and diameter from 74 to 145 nm confirmed by Field emission scanning electron microscopy (FESEM). The magnetic properties of the nanowires exhibited different levels of saturation magnetization, for α-Fe2O3 perpendicularly aligned direction (13.18 emu/g) and random direction (10.73 emu/g). Urea synthesis was done under magnetic field ranges from 0.0 to 2.5 T. The activation energy of α-Fe2O3 NWs for urea production is lower than NPs in the range of 0-1 T, whereas it is reversed for higher magnetic induction values. Fourier transform infrared spectroscopy (FTIR) confirmed the formation of urea at the peaks of 1690-1600 cm-1. This green urea employing magnetically induced method could be a contender to the Haber-Bosch process currently used by the current industry which utilizes high temperature and high pressure.

  4. Synthesis, structural and magnetic characterization of soft magnetic nanocrystalline ternary FeNiCo particles

    Energy Technology Data Exchange (ETDEWEB)

    Toparli, Cigdem [Department of Metallurgical & Materials Eng., Istanbul Technical University, 34469 Istanbul (Turkey); Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf (Germany); Ebin, Burçak [Department of Metallurgical & Materials Eng., Istanbul Technical University, 34469 Istanbul (Turkey); Nuclear Chemistry and Industrial Material Recycling, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, S-412 96 Gothenburg (Sweden); Gürmen, Sebahattin, E-mail: gurmen@itu.edu.tr [Department of Metallurgical & Materials Eng., Istanbul Technical University, 34469 Istanbul (Turkey)

    2017-02-01

    The present study focuses on the synthesis, microstructural and magnetic properties of ternary FeNiCo nanoparticles. Nanocrystalline ternary FeNiCo particles were synthesized via hydrogen reduction assisted ultrasonic spray pyrolysis method in single step. The effect of precursor concentration on the morphology and the size of particles was investigated. The syntheses were performed at 800 °C. Structure, morphology and magnetic properties of the as-prepared products were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) studies. Scherer calculation revealed that crystallite size of the ternary particles ranged between 36 and 60 nm. SEM and TEM investigations showed that the particle size was strongly influenced by the precursor concentration and Fe, Ni, Co elemental composition of individual particles was homogeneous. Finally, the soft magnetic properties of the particles were observed to be a function of their size. - Highlights: • Ternary FeNiCo alloy nanocrystalline particles were synthesized in a single step. • Cubic crystalline structure and spherical morphology was observed by XRD, SEM and TEM investigations. • The analysis of magnetic properties indicates the soft magnetic features of particles.

  5. Magnetic materials fundamentals, products, properties, applications

    CERN Document Server

    Hilzinger, Rainer

    2013-01-01

    At a practical level, this compendium reviews the basics of soft and hard magnetic materials, discusses the advantages of the different processing routes for the exploitation of the magnetic properties and hence assists in proper, fail-safe and economic application of magnetic materials. Essential guidelines and formulas for the calculation of the magnetic and electrical properties, temperature and long-term stability of permanent magnets, of inductive components and magnetic shielding are compiled. Selected fields of application and case studies illustrate the large diversity of technical applications. Application engineers will appreciate the comprehensive compilation of the properties and detailed characteristic curves of modern soft and hard magnetic materials. Materials scientists will enjoy the presentation of the different processing routes and their impact on the magnetic properties and students will profit from the survey from the basics of magnetism down to the applications in inductive components, ...

  6. Hybrid Pd/Fe{sub 3}O{sub 4} nanowires: Fabrication, characterization, optical properties and application as magnetically reusable catalyst for the synthesis of N-monosubstituted ureas under ligand-free conditions

    Energy Technology Data Exchange (ETDEWEB)

    Nasrollahzadeh, Mahmoud, E-mail: mahmoudnasr81@gmail.com [Department of Chemistry, Faculty of Science, University of Qom, Qom 37185-359 (Iran, Islamic Republic of); Azarian, Abbas [Department of Physics, University of Qom, Qom (Iran, Islamic Republic of); Ehsani, Ali [Department of Chemistry, Faculty of Science, University of Qom, Qom 37185-359 (Iran, Islamic Republic of); Sajadi, S.Mohammad [Department of Petroleum Geoscience, Faculty of Science, Soran University, PO Box 624, Soran, Kurdistan Regional Government (Iraq); Babaei, Ferydon [Department of Physics, University of Qom, Qom (Iran, Islamic Republic of)

    2014-07-01

    Highlights: • Preparation of Pd/Fe{sub 3}O{sub 4} nanowires as magnetically reusable catalysts. • The optical properties of the catalyst were studied using Gans theory. • N-arylation of benzylurea and in situ hydrogenolysis of 1-benzyl-3-arylureas. - Abstract: This paper reports the synthesis and use of Pd/Fe{sub 3}O{sub 4} nanowires, as magnetically separable catalysts for ligand-free amidation coupling reactions of aryl halides with benzylurea under microwave irradiation. Then, the in situ hydrogenolysis of the products was performed to afford the N-monosubstituted ureas from good to excellent yields. This method has the advantages of high yields, simple methodology and easy work up. The catalyst can be recovered by using a magnet and reused several times without significant loss of its catalytic activity. The catalyst was characterized using the powder XRD, SEM, EDS and UV–vis spectroscopy. Experimental absorbance spectra was compared with results from the Gans theory.

  7. Synthesis and magnetic properties of bacterial cellulose—ferrite (MFe2O4, M  =  Mn, Co, Ni, Cu) nanocomposites prepared by co-precipitation method

    Science.gov (United States)

    Sriplai, Nipaporn; Mongkolthanaruk, Wiyada; Pinitsoontorn, Supree

    2017-09-01

    The magnetic nanocomposites based on bacterial cellulose (BC) matrix and ferrite (MFe2O4, M  =  Mn, Co, Ni and Cu) nanoparticles (NPs) were fabricated. The never-dried and freeze-dried BC nanofibrils were used as templates and a co-precipitation method was applied for NPs synthesis. The nanocomposites were either freeze-dried or annealed before subjected to characterization. The x-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy showed that only MnFe2O4 and CoFe2O4 NPs could be successfully incorporated in the BC nanostructures. The results also indicated that the BC template should be freeze-dried prior to the co-precipitation process. The magnetic measurement by a vibrating sample magnetometer (VSM) showed that the strongest ferromagnetic signal was found for BC-CoFe2O4 nanocomposites. The morphological investigation by a scanning electron microscope (SEM) showed the largest volume fraction of NPs in the BC-CoFe2O4 sample which was complimentary to the magnetic property measurement. Annealing resulted in the collapse of the opened nanostructure of the BC composites. Invited talk at 5th Thailand International Nanotechnology Conference (Nano Thailand-2016), 27-29 November 2016, Nakhon Ratchasima, Thailand.

  8. Effect of synthesis methods with different annealing temperatures on micro structure, cations distribution and magnetic properties of nano-nickel ferrite

    Energy Technology Data Exchange (ETDEWEB)

    El-Sayed, Karimat [XRD Lab, Physics Department, Faculty of Science, Ain-Shams University, Cairo (Egypt); Mohamed, Mohamed Bakr, E-mail: mbm1977@yahoo.com [XRD Lab, Physics Department, Faculty of Science, Ain-Shams University, Cairo (Egypt); Hamdy, Sh.; Ata-Allah, S.S. [Reactor Physics Department, NRC, Atomic Energy Authority, P.O. Box 13759, Cairo (Egypt)

    2017-02-01

    Nano-crystalline NiFe{sub 2}O{sub 4} was synthesized by citrate and sol–gel methods at different annealing temperatures and the results were compared with a bulk sample prepared by ceramic method. The effect of methods of preparation and different annealing temperatures on the crystallize size, strain, bond lengths, bond angles, cations distribution and degree of inversions were investigated by X-ray powder diffraction, high resolution transmission electron microscope, Mössbauer effect spectrometer and vibrating sample magnetometer. The cations distributions were determined at both octahedral and tetrahedral sites using both Mössbauer effect spectroscopy and a modified Bertaut method using Rietveld method. The Mössbauer effect spectra showed a regular decrease in the hyperfine field with decreasing particle size. Saturation magnetization and coercivity are found to be affected by the particle size and the cations distribution. - Highlights: • Annealed nano NiFe{sub 2}O{sub 4} was prepared by different methods. • The crystallite sizes are critical. • Mössbauer spectra show superparamagnetic doublet. • Cations distributions by MÓ§ssbauer and Bertaut method are constituents. • Cations distribution are significantly affects the magnetic properties.

  9. Synthesis, structural, dielectric and magnetic properties of CuFe{sub 2}O{sub 4}/MnO{sub 2} nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Kashif, E-mail: kashiiu007@gmail.com [Department of Physics, International Islamic University, Islamabad (Pakistan); Bahadur, Ali [Department of Chemistry, Quaid-i-Azam University, Islamabad (Pakistan); Jabbar, Abdul [Department of Chemistry, Allama Iqbal Open University, Islamabad (Pakistan); Iqbal, Shahid [School of chemistry and chemical engineering, university of Chinese academy of sciences, Beijing 10049 (China); Ahmad, Ijaz [Department of Chemistry, Allama Iqbal Open University, Islamabad (Pakistan); Bashir, Muhammad Imran [Department of Physics, Quaid-i-Azam University, Islamabad (Pakistan)

    2017-07-15

    Novel nanocomposite of (1-x)CuFe{sub 2}O{sub 4}/xMnO{sub 2} [x=10% to 50 wt%] has been synthesized by two step wet chemical route without impurity. The x-ray diffraction analysis shows the formation of both phases with crystallite size 40–100 nm which is consist ant with estimated size of SEM.The FTIR spectra confirms the characteristics vibration of ferrites atoms at tetrahedral and octahedral sites along with Mn-O vibration mode, which also confirms the coexistence of both phases. The dielectric properties studied by LCR meter in frequency range of 1 K Hz to 2 MHz.The dielectric constant and tangent loss shows same dispersion of ferrites while a.c. conductivity decreases with increase in MnO{sub 2} contents. The real and imaginary part of impedance also calculated which shows decreasing trend at higher frequency. The magnetic characterization performed by vibrating sample magnetometer (VSM) at room temperature, which shows normal ferromagnetic behavior of ferrites but saturation magnetization and coercivity decreases with incorporation of MnO{sub 2} contents.

  10. Magnetic properties of diluted magnetic semiconductors

    NARCIS (Netherlands)

    Jonge, de W.J.M.; Swagten, H.J.M.

    1991-01-01

    A review will be given of the magnetic characteristics of diluted magnetic semiconductors and the relation with the driving exchange mechanisms. II–VI as well as IV–VI compounds will be considered. The relevance of the long-range interaction and the role of the carrier concentration will be

  11. Synthesis, characterization, temperature dependent electrical and magnetic properties of Ca{sub 3}Co{sub 4}O{sub 9} by a starch assisted sol–gel combustion method

    Energy Technology Data Exchange (ETDEWEB)

    Agilandeswari, K.; Ruban Kumar, A., E-mail: arubankumar@vit.ac.in

    2014-09-01

    In this present work we discussed the synthesis of pure Ca{sub 3}Co{sub 4}O{sub 9} ceramic powder by a starch assisted sol–gel combustion method. The products were characterized by powder X-ray diffraction (XRD), thermogravimetric and differential thermal analyses (TGA–DTA), Fourier transformation infrared spectroscopy (FTIR), scanning electron microscope (SEM) and UV–visible diffuse reflectance spectroscopy (DRS). X-ray diffraction pattern confirmed the formation of single phase Ca{sub 3}Co{sub 4}O{sub 9} at a sintering temperature of 1073 K, and it is also confirmed in the thermal analysis. SEM images indicate the presence of diffused microporous sphere like morphology and the grain sizes are in the range of 150–300 nm. Optical properties of Ca{sub 3}Co{sub 4}O{sub 9} ceramic show a band gap at an energy level of 2.10 eV. A maximum electrical resistivity of 0.002 mΩ cm was exhibited by Ca{sub 3}Co{sub 4}O{sub 9} that was decreased to 0.0012 mΩ cm, when the temperature increased from 300 K to 473 K. Dielectric studies were conducted at various temperatures from room temperature to 673 K and the results indicate that the space charge polarization contributes to the conduction mechanism. It also shows that the dielectric relaxation with activation energy is 0.96 eV. The magnetic properties as a function of temperature represent the ferri-paramagnetic phase transition at above 50 K. M–H curve shows the hysteresis loop with saturation magnetization (M{sub s}) and confirms the presence of soft magnetic materials. - Highlights: • Ca{sub 3}Co{sub 4}O{sub 9} has not yet been reported by this starch assisted sol–gel combustion method. • SEM image shows microporous sphere like morphology. • The optical and dielectric properties of Ca{sub 3}Co{sub 4}O{sub 9} sample were studied. • Temperature dependent magnetic property has been studied for Ca{sub 3}Co{sub 4}O{sub 9}. It behaves as a soft magnetic material at 5 K.

  12. Facile synthesis and enhanced magnetic, photocatalytic properties of one-dimensional Ag@Fe{sub 3}O{sub 4}-TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Xiaohua, E-mail: xhjia2003@126.com [School of Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, 212013 (China); Dai, Rongrong; Lian, Dandan; Han, Song [School of Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, 212013 (China); Wu, Xiangyang, E-mail: wuxy@ujs.edu.cn [School of Environment and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu, 212013 (China); Song, Haojie [Institute of Polymer Materials, School of Materials Science & Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2017-01-15

    Highlights: • One-dimensional triple heterostructure Ag@Fe{sub 3}O{sub 4}-TiO{sub 2} was successfully achieved by a facile co-precipitation and chemical-solution-deposition process method. • One-dimensional triple heterostructure Ag@Fe{sub 3}O{sub 4}-TiO{sub 2} exhibited enhanced photocatalytic properties and can be easily recovered by an extemal magnetic field. • The mechanisms for the enhanced photocatalytic effect of the heterostructure were discussed. - Abstract: Fe{sub 3}O{sub 4}-TiO{sub 2} heterostructures were synthesized through co-precipitation method based on TiO{sub 2} nanobelts. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibration sample magnetometry (VSM) were used to characterize the heterostructure nanocomposites. The results of XRD proved that the TiO{sub 2} nanobelt was anatase which was the most suitable crystal form for photocatalysis. SEM and TEM analysis indicated that Fe{sub 3}O{sub 4} nanoparticles were adhere to TiO{sub 2} nanobelts which have one-dimensional structure with 100–200 nm in width. The VSM measurements showed that the photocatalyst can be easily recovered by an extemal magnetic field. X-ray photoelectron spectroscopy (XPS) of Ag@Fe{sub 3}O{sub 4}-TiO{sub 2} nanocomposites studies confirm that Ag is in Ag{sup 0} state. Finally, the photodegradation of rhodamine B (RhB) by the obtained magnetic photocatalyst was investigated via UV–vis absorption spectra. The photocatalytic activity of the composites was observed to be lower compared to bare TiO{sub 2} due to the higher degree of recombination reactions after combined with Fe{sub 3}O{sub 4} nanoparticles. After coated the composite of 15% Fe{sub 3}O{sub 4}-TiO{sub 2} with Ag, the new nanocomposite of Ag@Fe{sub 3}O{sub 4}-TiO{sub 2} can be easily recovered after photocatalysis by an extemal magnetic field and showed enhanced photocatalytic activity. The mechanisms for the exhibited enhanced photocatalytic effect of

  13. Magnetic properties of layered superconductors

    International Nuclear Information System (INIS)

    Mansky, P.A.

    1993-01-01

    The organic superconductors (BEDT-TTF) 2 Cu(SNC) 2 and (TMTSF) 2 ClO 4 , with T c = 10K and 1.2K, have layered and highly anisotropic crystal structures. This thesis describes AC magnetic susceptibility measurements on these materials which illustrate the consequences of the discrete layered structure for the magnetic properties of the superconducting state. A DC magnetic field applied parallel to the layers of either material causes the rapid suppression of the AC screening response, and this indicates that the pinning restoring force for vortex motion parallel to the layers is anomalously weak in this orientation. This is believed to be due to the small size of the interlayer coherence length relative to the layer spacing. A simple estimate based on the energy and length scales relevant to Josephson coupled layers gives the correct order of magnitude for the pinning force. Pinning for vortices oriented perpendicular to the layers is larger by a factor of 500 for BEDT and 25 for TMTSF. When the DC field is applied at an angle to the layers, the initial suppression of the susceptibility is identical to that for a field parallel to the layers; when the field component normal to the layers exceeds a threshold, a sharp recovery of screening occurs. These observations indicate that the field initially enters the sample only in the direction parallel to the layers. The recovery of screening signals field penetration in the perpendicular direction at higher field strength, and is due to the onset of pinning by in-plane vortex cores. This magnetic open-quotes lock-inclose quotes effect is a qualitatively new behavior and is a direct consequence of weak interlayer coupling. The London penetration depth associated with interlayer currents is found to be on the order of hundreds of microns, comparable to that of a Josephson junction, and two to three orders of magnitude larger than for conventional superconductors

  14. Tunable dynamic response of magnetic gels: Impact of structural properties and magnetic fields

    Science.gov (United States)

    Tarama, Mitsusuke; Cremer, Peet; Borin, Dmitry Y.; Odenbach, Stefan; Löwen, Hartmut; Menzel, Andreas M.

    2014-10-01

    Ferrogels and magnetic elastomers feature mechanical properties that can be reversibly tuned from outside through magnetic fields. Here we concentrate on the question of how their dynamic response can be adjusted. The influence of three factors on the dynamic behavior is demonstrated using appropriate minimal models: first, the orientational memory imprinted into one class of the materials during their synthesis; second, the structural arrangement of the magnetic particles in the materials; and third, the strength of an external magnetic field. To illustrate the latter point, structural data are extracted from a real experimental sample and analyzed. Understanding how internal structural properties and external influences impact the dominant dynamical properties helps to design materials that optimize the requested behavior.

  15. Surface active monomers synthesis, properties, and application

    CERN Document Server

    Borzenkov, Mykola

    2014-01-01

    This brief includes information on the background?of and development of synthesis of various types of surface active monomers. The authors explain the importance of utilization of surface active monomers for creation of surface active polymers? and the various biomedical applications of such compounds . This brief introduces techniques for the synthesis of novel types of surface active monomers, their colloidal and polymerizable properties and application for needs of medicine and biology.

  16. Facile synthesis of enzyme-embedded magnetic metal-organic frameworks as a reusable mimic multi-enzyme system: mimetic peroxidase properties and colorimetric sensor.

    Science.gov (United States)

    Hou, Chen; Wang, Yang; Ding, Qinghua; Jiang, Long; Li, Ming; Zhu, Weiwei; Pan, Duo; Zhu, Hao; Liu, Mingzhu

    2015-11-28

    This work reports a facile and easily-achieved approach for enzyme immobilization by embedding glucose oxidase (GOx) in magnetic zeolitic imidazolate framework 8 (mZIF-8) via a de novo approach. As a demonstration of the power of such materials, the resulting GOx embedded mZIF-8 (mZIF-8@GOx) was utilized as a colorimetric sensor for rapid detection of glucose. This method was constructed on the basis of metal-organic frameworks (MOFs), which possessed very fascinating peroxidase-like properties, and the cascade reaction for the visual detection of glucose was combined into one step through the mZIF-8@GOx based mimic multi-enzyme system. After characterization by electron microscopy, X-ray diffraction, nitrogen sorption, fourier transform infrared spectroscopy and vibrating sample magnetometry, the as-prepared mZIF-8@GOx was confirmed with the robust core-shell structure, the monodisperse nanoparticle had an average diameter of about 200 nm and displayed superparamagnetism with a saturation magnetization value of 40.5 emu g(-1), it also exhibited a large surface area of 396.10 m(2) g(-1). As a peroxidase mimic, mZIF-8 was verified to be highly stable and of low cost, and showed a strong affinity towards H2O2. Meanwhile, the mZIF-8 embedded GOx also exhibited improved activity, stability and greatly enhanced selectivity in glucose detection. Moreover, the mZIF-8@GOx had excellent recyclability with high activity (88.7% residual activity after 12 times reuse).

  17. Metal-organic and supramolecular networks driven by 5-chloronicotinic acid: Hydrothermal self-assembly synthesis, structural diversity, luminescent and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Zhu-Qing, E-mail: zqgao2008@163.com [School of Chemical and Biological Engineering, Taiyuan University of Science and Technology, Taiyuan 030021 (China); Li, Hong-Jin [School of Chemical and Biological Engineering, Taiyuan University of Science and Technology, Taiyuan 030021 (China); Gu, Jin-Zhong, E-mail: gujzh@lzu.edu.cn [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Zhang, Qing-Hua [School of Chemical and Biological Engineering, Taiyuan University of Science and Technology, Taiyuan 030021 (China); Kirillov, Alexander M. [Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049–001 Lisbon (Portugal)

    2016-09-15

    Four new crystalline solids, namely [Co{sub 2}(µ{sub 2}-5-Clnic){sub 2}(µ{sub 3}-5-Clnic){sub 2}(µ{sub 2}-H{sub 2}O)]{sub n} (1), [Co(5-Clnic){sub 2}(H{sub 2}O){sub 4}]·2(5-ClnicH) (2), [Pb(µ{sub 2}-5-Clnic){sub 2}(phen)]{sub n} (3), and [Cd(5-Clnic){sub 2}(phen){sub 2}]·3H{sub 2}O (4) were generated by hydrothermal self-assembly methods from the corresponding metal(II) chlorides, 5-chloronicotinic acid (5-ClnicH) as a principal building block, and 1,10-phenanthroline (phen) as an ancillary ligand (optional). All the products 1–4 were characterized by IR spectroscopy, elemental analysis, thermogravimetric (TGA), powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. Their structures range from an intricate 3D metal-organic network 1 with the 3,6T7 topology to a ladder-like 1D coordination polymer 3 with the 2C1 topology, whereas compounds 2 and 4 are the discrete 0D monomers. The structures of 2 and 4 are further extended (0D→2D or 0D→3D) by hydrogen bonds, generating supramolecular networks with the 3,8L18 and ins topologies, respectively. Synthetic aspects, structural features, thermal stability, magnetic (for 1) and luminescent (for 3 and 4) properties were also investigated and discussed. - Graphical abstract: A new series of crystalline solids was self-assembled and fully characterized; their structural, topological, luminescent and magnetic features were investigated. Display Omitted.

  18. Rapid and large-scale synthesis of Co3O4 octahedron particles with very high catalytic activity, good supercapacitance and unique magnetic property

    CSIR Research Space (South Africa)

    Chowdhury, M

    2015-12-01

    Full Text Available Scarcity of rapid and large scale synthesis of functional materials, hinders the progress from laboratory scale to commercial applications. In this study, we report a rapid and large scale synthesis of Co(Sub3)O(sub4) octahedron micron size (1.3 µm...

  19. Synthesis, magnetic and spectral studies of lanthanide(III) chloride complexes of hydrazones of isonicotinic acid hydrazide

    International Nuclear Information System (INIS)

    Agarwal, R.K.; Agarwal, Himanshu; Prasad, Ram

    1996-01-01

    The synthesis, magnetic and spectral properties of trivalent lanthanide chlorides with N-isonicotinamidobenzalaldimine (INH-BENZ), N-isonicotinamidoanisalaldimine (INH-ANSL) and N-isonicotinamido-p-dimethylaminobenzalaldimine (INH-PDAB) are described. 13 refs., 2 tabs

  20. Magnetic Properties of Magnetic Nanoparticles for Efficient Hyperthermia

    Directory of Open Access Journals (Sweden)

    Ihab M. Obaidat

    2015-01-01

    Full Text Available Localized magnetic hyperthermia using magnetic nanoparticles (MNPs under the application of small magnetic fields is a promising tool for treating small or deep-seated tumors. For this method to be applicable, the amount of MNPs used should be minimized. Hence, it is essential to enhance the power dissipation or heating efficiency of MNPs. Several factors influence the heating efficiency of MNPs, such as the amplitude and frequency of the applied magnetic field and the structural and magnetic properties of MNPs. We discuss some of the physics principles for effective heating of MNPs focusing on the role of surface anisotropy, interface exchange anisotropy and dipolar interactions. Basic magnetic properties of MNPs such as their superparamagnetic behavior, are briefly reviewed. The influence of temperature on anisotropy and magnetization of MNPs is discussed. Recent development in self-regulated hyperthermia is briefly discussed. Some physical and practical limitations of using MNPs in magnetic hyperthermia are also briefly discussed.

  1. Robust Magnetic Properties of a Sublimable Single-Molecule Magnet.

    Science.gov (United States)

    Kiefl, Evan; Mannini, Matteo; Bernot, Kevin; Yi, Xiaohui; Amato, Alex; Leviant, Tom; Magnani, Agnese; Prokscha, Thomas; Suter, Andreas; Sessoli, Roberta; Salman, Zaher

    2016-06-28

    The organization of single-molecule magnets (SMMs) on surfaces via thermal sublimation is a prerequisite for the development of future devices for spintronics exploiting the richness of properties offered by these magnetic molecules. However, a change in the SMM properties due to the interaction with specific surfaces is usually observed. Here we present a rare example of an SMM system that can be thermally sublimated on gold surfaces while maintaining its intact chemical structure and magnetic properties. Muon spin relaxation and ac susceptibility measurements are used to demonstrate that, unlike other SMMs, the magnetic properties of this system in thin films are very similar to those in the bulk, throughout the full volume of the film, including regions near the metal and vacuum interfaces. These results exhibit the robustness of chemical and magnetic properties of this complex and provide important clues for the development of nanostructures based on SMMs.

  2. Modern permanent magnetic materials - preparation and properties

    International Nuclear Information System (INIS)

    Rodewald, W.

    1989-01-01

    First of all, the basic properties of the classical (steel, AlNiCo) permanent magnetic materials and the modern rare-earth (RE) permanent magnetic materials are compared. Since the properties of RE permanent magnets depend on the particular production process, the fundamentals of the main industrial processes (powder metallurgy, rapid-solidification technique) are described and the typical properties are explained. Furthermore the production processes in development such as mechanical alloying, melt spinning technique and extrusion upsetting are briefly outlined. For applying the permanent magnets, they have to be completely magnetized. The magnetization behaviour of the various RE permanent magnets is discussed by means of the internal demagnetization curve. Finally the various influences on the temperature stability of RE permanent magnets are compiled. (orig./MM) [de

  3. Electrochemical synthesis of magnetic nanostructures using anodic aluminum oxide templates

    Science.gov (United States)

    Gong, Jie

    In this dissertation, template electrodeposition was employed to fabricate high quality magnetic nanostructures suited for the reliable investigation of novel spintronics phenomena such as CIMS, BMR, and CPP-GMR. Several critical aspects/steps relating to the synthesis process were investigated in this work. In order to obtain high quality magnetic nanostructures, free-standing and Si-supported anodic aluminum oxide templates with closely controlled pore diameters, lengths, as well as constriction sizes, were synthesized by anodization, followed by appropriate post-processing. The pore opening size on the barrier layer can be controlled down to 5 nm by ion beam etching. After optimization of the compositional, structural, and magnetic properties of homogeneous FeCoNiCu layers electrodeposited under different conditions, the pulsed deposition process of FeCoNI/Cu multilayers on n-Si was studied. The influence of Cu deposition potential and Fe2+ concentration on microstructure, chemical and electrochemical properties, magnetic properties, and hence magnetotransport properties were assessed. The dissolution of the FM layer during potential transition was minimized in order to control interface sharpness. Combined with the systematic sublayer thickness and FM layer composition optimization, unprecedented GMR sensitivity of 0.11%/Oe at 5-15 Oe was obtained. Growth of multilayer nanowires was performed, and contact to a single wire was attempted using an electrochemical technique. We succeeded in addressing a small number of nanowires and measured a CPP-GMR of 17%. Template electrodeposition thus provides a promising way to repeatably fabricate prototypes for spin dependent transport studies.

  4. Two-dimensional layer architecture assembled by Keggin polyoxotungstate, Cu(II)-EDTA complex and sodium linker: Synthesis, crystal structures, and magnetic properties

    International Nuclear Information System (INIS)

    Liu Hong; Xu Lin; Gao Guanggang; Li Fengyan; Yang Yanyan; Li Zhikui; Sun Yu

    2007-01-01

    Reaction of Keggin polyoxotungstate with copper(II)-EDTA (EDTA=ethylenediamine tetraacetate) complex under mild conditions led to the formation of hybrid inorganic-organic compounds Na 4 (OH)[(Cu 2 EDTA)PW 12 O 40 ].17H 2 O (1) and Na 4 [(Cu 2 EDTA)SiW 12 O 40 ].19H 2 O (2). The single-crystal X-ray diffraction analyses reveal their two structural features: (1) one-dimensional chain structure consisting of Keggin polyoxotungstate and copper(II)-EDTA complex; (2) Two-dimensional layer architecture assembled by the one-dimensional chain structure and sodium linker. The results of magnetic measurements in the temperature range 300-2 K indicated the existence of ferromagnetic exchange interactions between the Cu II ions for both compounds. In addition, TGA analysis, IR spectra, and electrochemical properties were also investigated to well characterize these two compounds. - Graphical abstract: Two new polyoxometalate-based hybrids, Na 4 (OH)[Cu 2 (EDTA)PW 12 O 40 ].17H 2 O (1) and Na 4 [Cu 2 (EDTA)SiW 12 O 40 ].19H 2 O (2), have been synthesized and structurally characterized, which consist of one-dimensional chain structure assembled by Keggin polyoxotungstate and copper(II)-EDTA complex. The chains are further connected to form two-dimensional layer architecture assembled by the one-dimensional chain structure and sodium linker

  5. Synthesis, structure, and electrochemistry and magnetic properties of a novel 1D homochiral MnIII(5-Brsalen) coordination polymer with left-handed helical character

    Science.gov (United States)

    Dong, Dapeng; Yu, Naisen; Zhao, Haiyan; Liu, Dedi; Liu, Jia; Li, Zhenghua; Liu, Dongping

    2016-01-01

    A novel homochiral manganese (III) Mn(5-Brsalen) coordination polymer with left-handed helical character by spontaneous resolution on crystallization by using Mn(5-Brsalen) and 4,4-bipyridine, [MnIII(5-Brsalen)(4,4-bipy)]·ClO4·CH3OH (1) (4,4-bipy = 4,4-bipyridine) has been synthesized and structurally characterized by X-ray single-crystal diffraction, elemental analysis and infrared spectroscopy. In compound 1, each manganese(III) anion is six-coordinate octahedral being bonded to four atoms of 5-Brsalen ligand in an equatorial plane and two nitrogen atoms from a 4,4-bipyridine ligand in axial positions. The structure of compound 1 can be described a supramolecular 2D-like structure which was formed by the intermolecular π-stacking interactions between the neighboring chains of the aromatic rings of 4,4-bipyridine and 5-Brsalen molecules. UV-vis absorption spectrum, electrochemistry and magnetic properties of the compound 1 have also been studied.

  6. 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)

  7. Pillared-layer microporous metal-organic frameworks constructed by robust hydrogen bonds. Synthesis, characterization, and magnetic and adsorption properties of 2,2'-biimidazole and carboxylate complexes.

    Science.gov (United States)

    Ding, Bing-Bing; Weng, Yan-Qin; Mao, Zong-Wan; Lam, Chi-Keung; Chen, Xiao-Ming; Ye, Bao-Hui

    2005-11-28

    Two new isostructural complexes [M(H2biim)3][M(btc)(Hbiim)].2H2O (M = Co, (1); M = Ni, (2)) (btc = 1,3,5-benzenetricarboxylate; H2biim = 2,2'-biimidazole) have been synthesized and characterized by single-crystal X-ray diffraction. They present a unique structure consisting of two distinct units: the monomeric cations [M(H2biim)3]2+ and the two-dimensional (2D) anionic polymer [M(Hbiim)(btc)]2-. In the anionic moiety, the Hbiim- monoanion is simultaneously coordinated to one metal atom in a bidentate mode and further to another metal atom in a monodentate mode. The imidazolate groups bridge the two adjacent metal ions into a helical chain which is further arranged in left- and right-handed manners. These chains are bridged by btc ligands into a 2D brick wall structure. The most interesting aspect is that the [M(H2biim)3]2+ cations act as pillars and link the anionic layers via robust heteromeric hydrogen-bonded synthons (9) and (7) formed by the uncoordinated oxygen atoms of carboxylate groups and the H2biim ligands, resulting in a microporous metal-organic framework with one-dimensional (1D) channels (ca. 11.85 angstroms x 11.85 angstroms for 1 and 11.43 angstroms x 11.43 angstroms for 2). Magnetic properties of these two complexes have also been studied in the temperature range of 2-300 K, and their magnetic susceptibilities obey the Curie-Weiss law in the temperature range of 20-300 K (for 1) and 2-300 K (for 2), respectively, showing anti-ferromagnetic coupling through imidazolate bridging. Taking into consideration the Heisenberg infinite chain model as well as the possibility of chain-to-chain and chain-to-cation interactions, the anti-ferromagnetic exchange of 2 is analyzed via a correction for the molecular field, giving the values of g(cat) = 2.296, g(Ni) = 2.564, J = -13.30 cm(-1), and zJ' = -0.017 cm(-1). The microporous frameworks are stable at ca. 350 degrees C. They do not collapse after removal of the guest water molecules in the channels, and they

  8. SYNTHESIS AND CHARACTERIZATION OF ADVANCED MAGNETIC MATERIALS

    Energy Technology Data Exchange (ETDEWEB)

    Monica Sorescu

    2004-09-22

    The work described in this grant report was focused mainly on the properties of novel magnetic intermetallics. In the first project, we synthesized several 2:17 intermetallic compounds, namely Nd{sub 2}Fe{sub 15}Si{sub 2}, Nd{sub 2}Fe{sub 15}Al{sub 2}, Nd{sub 2}Fe{sub 15}SiAl and Nd{sub 2}Fe{sub 15}SiMn, as well as several 1:12 intermetallic compounds, such as NdFe{sub 10}Si{sub 2}, NdFe{sub 10}Al{sub 2}, NdFe{sub 10}SiAl and NdFe{sub 10}MnAl. In the second project, seven compositions of Nd{sub x}Fe{sub 100-x-y}B{sub y} ribbons were prepared by a melt spinning method with Nd and B content increasing from 7.3 and 3.6 to 11 and 6, respectively. The alloys were annealed under optimized conditions to obtain a composite material consisting of the hard magnetic Nd{sub 2}Fe{sub 14}B and soft magnetic {alpha}-Fe phases, typical of a spring magnet structure. In the third project, intermetallic compounds of the type Zr{sub 1}Cr{sub 1}Fe{sub 1}T{sub 0.8} with T = Al, Co and Fe were subjected to hydrogenation. In the fourth project, we performed three crucial experiments. In the first experiment, we subjected a mixture of Fe{sub 3}O{sub 4} and Fe (80-20 wt %) to mechanochemical activation by high-energy ball milling, for time periods ranging from 0.5 to 14 hours. In the second experiment, we ball-milled Fe{sub 3}O{sub 4}:Co{sup 2+} (x = 0.1) for time intervals between 2.5 and 17.5 hours. Finally, we exposed a mixture of Fe{sub 3}O{sub 4} and Co (80-20 wt %) to mechanochemical activation for time periods ranging from 0.5 to 10 hours. In all cases, the structural and magnetic properties of the systems involved were elucidated by X-ray diffraction (XRD), Moessbauer spectroscopy and hysteresis loop measurements. The four projects resulted in four papers, which were published in Intermetallics, IEEE Transactions on Magnetics, Journal of Materials Science Letters and Materials Chemistry and Physics. The contributions reveal for the first time in literature the effect of

  9. Synthesis and characterization of luminescence magnetic nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Kiplagat, Ayabei [DST/Mintek Nanotechnology Innovation Centre, Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville (South Africa); Onani, Martin O., E-mail: monani@uwc.ac.za [DST/Mintek Nanotechnology Innovation Centre, Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville (South Africa); Meyer, Mervin [DST/Mintek Nanotechnology Innovation Centre, Department of Biotechnology, University of the Western Cape, Private Bag X17, Bellville (South Africa); Akenga, Teresa A. [Department of Chemistry, University of Eldoret, P.O. Box 1125, Eldoret (Kenya); Dejene, Francis B. [Department of Physics, University of the Free State, QwaQwa Campus, Private Bag X13, Phuthadithaba 9866 (South Africa)

    2016-01-01

    We report a new type of indium based quantum dots which were conjugated to the magnetic Fe{sub 2}O{sub 3} nanoparticles. They were characterized by photoluminescence (PL), high resolution transmission electron microscopy (HRTEM), superconducting quantum interference device (SQUID) and fourier transform infra-red (FTIR). The photoluminescence characteristics of the coupled and uncoupled indium based quantum dots were investigated to determine whether the fluorescing property could be retained in the bifunctional system. Generally, the PL intensity of the quantum dots was observed to reduce significantly and with huge red shift most probably due to quenching effects for the MNPs. The average size of the coupled nanoparticles were found to range between 4 and 5 nm for the quantum dots and range of 6–13 nm for the Fe{sub 2}O{sub 3} magnetic nanoparticles as revealed by both HRTEM and XRD. The highest magnetic saturation reached for both bare and functionalized magnetic nanoparticles was 68.58 emu/g. The FTIR data revealed that the postulated functional groups were actually present in both the bare and functionalized nanoparticles. For instance, Fe–O was observed at around 580 cm{sup −1}, O–H at 3432 cm{sup −1} and thiol group at 2929 cm{sup −1} for meso-2,3-dimercaptosuccinic acid capped Fe{sub 2}O{sub 3} magnetic nanoparticles. The energy dispersive spectroscopy (EDS) also confirmed that all the elements of the nanocomposite were actually present in the designed material.

  10. Magnetic properties of Fe-Nd silica glass ceramics

    Science.gov (United States)

    Nayak, Manjunath T.; Desa, J. A. Erwin; Babu, P. D.

    2018-04-01

    Soda lime silica glass ceramics containing iron and neodymium have been synthesized. The XRD pattern revealed that the glass samples devitrified into multiple phases. Fe2O3 as an initial component converted into Fe3O4 in the sample during the synthesis, and was the main contributor to the magnetic property of the sample. The inclusion of Nd was found to enhance the magnetization of the sample at 5K. The coercivity of the sample increased with decrease in temperature from room to 5K.

  11. Annealing effects on magnetic properties of silicone-coated iron-based soft magnetic composites

    Science.gov (United States)

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

    2012-03-01

    This paper focuses on novel iron-based soft magnetic composites synthesis utilizing high thermal stability silicone resin to coat iron powder. The effect of an annealing treatment on the magnetic properties of synthesized magnets was investigated. The coated silicone insulating layer was characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. Silicone uniformly coated the powder surface, resulting in a reduction of the imaginary part of the permeability, thereby increasing the electrical resistivity and the operating frequency of the synthesized magnets. The annealing treatment increased the initial permeability, the maximum permeability, and the magnetic induction, and decreased the coercivity. Annealing at 580 °C increased the maximum permeability by 72.5%. The result of annealing at 580 °C shows that the ferromagnetic resonance frequency increased from 2 kHz for conventional epoxy resin coated samples to 80 kHz for the silicone resin insulated composites.

  12. Chemical Synthesis of alpha-Iron Cobalt and Metastable gamma-Iron Nickel Magnetic Nanoparticles with Tunable Magnetic Properties for Study of RF Heating and Magnetomechanical Responses in Polymeric Systems

    Science.gov (United States)

    McNerny, Katie L.

    The successful development of functionalized magnetic nanoparticles (MNPs) is necessary for a variety of biomedical applications including magnetic tagging of cells, bioseparation, cell sorting, cell tracking, targeted drug delivery, thermablative cancer therapies, diagnostics and sensing applications. For effective performance in many of these applications, the MNPs must be stable at various temperatures and chemical environments while also being easily dispersed in a variety of media. Chemical synthesis techniques have been developed to achieve desirable shapes, sizes and compositions of Fe-Co, Fe-Ni, as well as other Fe-based ternary alloy MNPs. These MNPs have been functionalized with surfactants, polymers, and antibodies for suspension in aqueous fluids that can be delivered intravenously to a desired location in the body and subsequently manipulated by alternating (AC) and direct (DC) magnetic fields. An exciting application for the gamma-FeNi MNPs that will be investigated is self-regulated heating of cancer tissue. Cancerous tissue is known to be more thermally sensitive than healthy tissue due to irregularities in tumor vasculature, and therefore MNPs can be used to heat and kill these cells while leaving healthy tissue unharmed. gamma-FeNi MNPs have tunable Curie temperatures (TC's) and can be further adjusted by the addition of an antiferromagnetic element such as Mn or Cr to reach temperatures required for killing cancer cells (between 40 and 50°C). The TC acts as an upper limit to heating as the material switches from being ferromagnetic to paramagnetic. These MNPs have been synthesized and characterized, and a model for self-regulated heating has been demonstrated. The vision for this project is to eventually functionalize the particles with a tumor-specific tag, for instance Herceptin, and to potentially attach a chemotherapeutic agent to the MNPs for combined heating and drug delivery. Transmission electron microscopy (TEM) has been used to show

  13. Green urea synthesis catalyzed by hematite nanowires in magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Yahya, Noorhana, E-mail: noorhana_yahya@petronas.com.my; Qureshi, Saima; Rehman, Zia ur; Alqasem, Bilal; Fai Kait, Chong

    2017-04-15

    The catalytic activity of hematite (α-Fe{sub 2}O{sub 3}) nanowires under the influence of magnetic field on urea synthesis is considered green. The adsorption and subsequent dissociative reaction of hydrogen, nitrogen and carbon dioxide gases on the α-Fe{sub 2}O{sub 3} (111) nanowires were investigated using the density functional theory (DFT) method. The average adsorption energy is −4.12 kcal/mole at different sites. The adsorption of gases resulted in a difference in density and net spin of electrons from 68 to 120 and 0–21 respectively. In addition, it induces magnetic moment value of 36.33 µB, which confirms the enhanced magnetic behaviour of hematite. α-Fe{sub 2}O{sub 3} nanowires (NWs) synthesized by heating iron wire in a box furnace at (750−800) °C and as synthesized α-Fe{sub 2}O{sub 3} nanoparticles (NPs) were received to use as a catalyst in the magnetic reaction of urea synthesis. X-ray Diffractometer (XRD) confirms the peaks of rhombohedral structure of α-Fe{sub 2}O{sub 3} and Raman spectrum analyses confirms the α-Fe{sub 2}O{sub 3} peaks at 410 cm{sup −1}, 500 cm{sup −1} and 616 cm{sup −1}. The needle-like shape of hematite nanowires with length ranging from 16–25) μm and diameter from 74 to 145 nm confirmed by Field emission scanning electron microscopy (FESEM). The magnetic properties of the nanowires exhibited different levels of saturation magnetization, for α-Fe{sub 2}O{sub 3} perpendicularly aligned direction (13.18 emu/g) and random direction (10.73 emu/g). Urea synthesis was done under magnetic field ranges from 0.0 to 2.5 T. The activation energy of α-Fe{sub 2}O{sub 3} NWs for urea production is lower than NPs in the range of 0–1 T, whereas it is reversed for higher magnetic induction values. Fourier transform infrared spectroscopy (FTIR) confirmed the formation of urea at the peaks of 1690–1600 cm{sup −1}. This green urea employing magnetically induced method could be a contender to the Haber-Bosch process

  14. Magnetic properties of metals and alloys

    International Nuclear Information System (INIS)

    Lyuborskij, F.E.; Livingston, D.D.; Chin, Zh.I.

    1987-01-01

    The nature of magnetic properties of materials and their dependence on the composition and the material structure are described. Properties and application of such materials as the alloys of the Fe-Ni-Co, Fe-Cr-Co, Co-rare earth, Fe-Si, Ni-Se system are considered. Application outlook for amorphous alloys of the (Fe, Ni, Co) 80 (metalloid) 20 type is shown. Methods for magnetic property measurement are pointed out

  15. Study on magnetic property and fracture behavior of magnetic materials

    International Nuclear Information System (INIS)

    Miya, Kenzo; Demachi, Kazuyuki; Aoto, Kazumi; Nagae, Yuji

    2002-04-01

    Establishment of evaluation methods of material degradation before crack initiation is needed very much to enhance the reliability of structural components. We remark magnetic methods in this report. Our objectives are to reveal the relation between degradation and magnetic property and to develop evaluation methods of material degradation, especially plastic deformation and stress corrosion cracking (SCC). In the former part of this report, evaluation methods for plastic deformation are discussed. At first, the study that shows the relation between the magnetic flux leakage and plastic deformation is reviewed. We developed the inverse analysis method of magnetization to specify the degradation distribution. Moreover, we propose inverse analysis of magnetic susceptibility for quantitative evaluation. In the latter part, the topic is SCC. We measured the magnetic flux leakage from the sample induced a SCC crack (Inconel 600). Inconel 600 is a paramagnetic material at room temperature but the sample shows ferromagnetic and the magnetic flux leakage was changed near the SCC crack. The possibility of detection of a SCC crack is shown by the inverse analysis result from the magnetic flux leakage. Finally, it is recognized by observation of the micro magnetic distributions by using a magnetic force microscope that the magnetization has relation with chromium depletion near grain boundaries and it is weak near the SCC crack. From these results, the magnetic method is very effective for evaluation of degradation. (author)

  16. The Characterization of the Magnetic Properties of Soft Magnetic Materials

    DEFF Research Database (Denmark)

    Larsen, Raino Michael

    1996-01-01

    The hysteresis curve and magnetic properties such as permeability, saturation induction, residual induction, coercive force and hysteresis losses are presented. The design and construction of equipment making it possible to measure true DC-values as well as AC-properties of toroid rings and cylin......The hysteresis curve and magnetic properties such as permeability, saturation induction, residual induction, coercive force and hysteresis losses are presented. The design and construction of equipment making it possible to measure true DC-values as well as AC-properties of toroid rings...

  17. Dextran Nanoparticle Synthesis and Properties.

    Science.gov (United States)

    Wasiak, Iga; Kulikowska, Aleksandra; Janczewska, Magdalena; Michalak, Magdalena; Cymerman, Iwona A; Nagalski, Andrzej; Kallinger, Peter; Szymanski, Wladyslaw W; Ciach, Tomasz

    2016-01-01

    Dextran is widely exploited in medical products and as a component of drug-delivering nanoparticles (NPs). Here, we tested whether dextran can serve as the main substrate of NPs and form a stable backbone. We tested dextrans with several molecular masses under several synthesis conditions to optimize NP stability. The analysis of the obtained nanoparticles showed that dextran NPs that were synthesized from 70 kDa dextran with a 5% degree of oxidation of the polysaccharide chain and 50% substitution with dodecylamine formed a NP backbone composed of modified dextran subunits, the mean diameter of which in an aqueous environment was around 100 nm. Dextran NPs could be stored in a dry state and reassembled in water. Moreover, we found that different chemical moieties (e.g., drugs such as doxorubicin) can be attached to the dextran NPs via a pH-dependent bond that allows release of the drug with lowering pH. We conclude that dextran NPs are a promising nano drug carrier.

  18. Magnetic Properties of NdAl2

    DEFF Research Database (Denmark)

    Bak, P.

    1974-01-01

    The magnetic properties of NdAl2 are calculated using a Hamiltonian including crystal-field and isotropic exchange interaction terms. A two-dimensional mean-field theory is evaluated to calculate single-crystal magnetization curves. It is shown that the magnetic properties can be understood using...... the crystal-field parameters derived from the magnetic exciton spectrum measured by Houmann et al. by means of inelastic neutron scattering. The combined lambda -Schottky anomaly in the heat capacity is explained. No additional parameters are introduced....

  19. Synthesis and study of the magnetic properties of thallium-based over-doped superconducting compounds; Synthese et etude des proprietes magnetiques des composes supraconducteurs surdopes a base de thallium

    Energy Technology Data Exchange (ETDEWEB)

    Opagiste, C.

    1994-07-01

    The synthesis, structure and magnetic properties of the normal and superconducting states of over-doped Tl{sub 2} Ba{sub 2} Cu O{sub 6{+-}x} and Tl{sub 2} Ba{sub 2} Ca Cu{sub 2} O{sub 8{+-}x} superconducting compounds, are presented. Synthesis under high pressure using Tl{sub 2} Ba{sub 2} O{sub 5} as a precursor avoids thallium losses and Ba Cu O{sub 2} formation. The entire over-doped region has been investigated (Tc ranging from 0 to 92 K) and the different stability zones for the two crystallographic structures have been explored. The orthorhombic structure is shown to be stoichiometric in cations, while the tetragonal one could present thallium deficiency. Clear correlations have been established between Tc and the lattice parameters for the two phases. It has been observed that the Meissner fraction increased with Tc and that the reversibility domain was more extended for samples having a Tc near the maximal value, which must be linked to the decrease of the anisotropy with over-doping. In the reversible regime, the mixed state is affected by thermal fluctuations around Tc. Evolution of the penetration depth with Tc is examined; it shows that the optimum doped compound (maximal Tc) behaves as a BCS type superconductor. The over-doping results in a penetration depth behaviour which strongly deviates from the standard model (BCS, two fluids). The zero temperature, obtained by extrapolation, seems to be independent of the over-doping. 54 figs., 3 tabs., 168 refs.

  20. Nanocrystalline permanent magnets with enhanced properties

    International Nuclear Information System (INIS)

    Leonowicz, M.

    2002-01-01

    Parameters of permanent magnets result from the combination of intrinsic properties such as saturation magnetization, magnetic exchange, and magnetocrystalline energy, as well as microstructural parameters such as phase structure, grain size, and orientation. Reduction of grain size into nanocrystalline regime (∼ 50 nm) leads to the enhanced remanence which derives from ferromagnetic exchange coupling between highly refined grains. In this study the fundamental phenomena, quantities, and structure parameters, which define nanophase permanent magnets are presented and discussed. The theoretical considerations are confronted with experimental data for nanocrystalline Sm-Fe-N type permanent magnets. (author)

  1. 2D and 3D organisation of nano-particles: synthesis and specific properties

    International Nuclear Information System (INIS)

    Taleb, Abdelhafed

    1998-01-01

    The first part of this research thesis addresses the synthesis of nano-particles of silver and cobalt in the inverse micellar system, and highlights the feasibility of two- and three-dimensional structures of these particles. The author first presents the micellar system (micro-emulsions, surfactant, properties of inverse micelles, functionalized inverse micelles, application to the synthesis of nano-particles), and then reports the study of the synthesis and organisation of colloids in 2D and 3D. He also reports the study of optical properties of metallic colloids: free electron approximation, optical properties of electron gases, optical properties of colloids, optical response of two-dimensional and three-dimensional nano-structures. The magnetic properties of colloids are then studied: magnetism of the massive metallic state, magnetic properties of nano-particles (influence of size, interactions and field, notions of magnetic order and disorder), effect of organisation. The second part of this thesis is made of a set of published articles: Synthesis of highly mono-disperse silver nano-particles from AOT reverse micelles (a way to 2D and 3D self-organisation), Optical properties of self-assembled 2D and 3D super-lattices of silver nano-particles, Collective optical properties of silver nano-particles organised in 2D super-lattices, Self assembled in 2D cobalt nano-sized particles, Self organisation of magnetic nano-sized cobalt particles, Organisation in 2D cobalt nano-particles (synthesis, characterization and magnetic properties) [fr

  2. Synthesis, crystal structure and magnetic property of a new 1D molecular material [1-(4'-chlorobenzyl)-4-aminopyridinium](+) bis(maleonitriledithiolato)nickel(-)

    International Nuclear Information System (INIS)

    Ni Chunlin; Dang Dongbin; Li Yizhi; Gao Song; Ni Zhaoping; Tian Zhengfang; Meng Qingjin

    2005-01-01

    A new ion-pair complex, [1-(4'-chlorobenzyl)-4-aminopyridinium](+)bis(maleonitrile-dithiolato) nickel(-),[ClbzPyNH 2 ][Ni(mnt) 2 ] (1), has been prepared and characterized. X-ray single crystal structure conforms that the Ni(mnt) 2 - anions and [ClbzPyNH 2 ] + cations of 1 form completely segregated uniform stacking columns with the Ni...Ni distance 3.944A in the Ni(mnt) 2 - stacking column. The temperature dependence of the magnetic susceptibility reveals that 1 undergoes a magnetic transition, and exhibits ferromagnetic interaction in the high-temperature phase and spin gap system in the low-temperature phase

  3. Synthesis of flower-like BaTiO3/Fe3O4 hierarchically structured particles and their electrorheological and magnetic properties.

    Science.gov (United States)

    Wang, Baoxiang; Yin, Yichao; Liu, Chenjie; Yu, Shoushan; Chen, Kezheng

    2013-07-21

    Flower-like BaTiO3/Fe3O4 hierarchically structured particles composed of nano-scale structures on micro-scale materials were synthesized by a simple solvothermal approach and characterized by the means of X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), magnetic testing and rotary viscometer. The influences on the morphology and structure of solvothermal times, type and amount of surfactant, EG : H2O ratio, etc. were studied. Magnetic testing results show that the samples have strong magnetism and they exhibit superparamagnetic behavior, as evidenced by no coercivity and the remanence at room temperature, due to their very small sizes, observed on the M-H loop. The saturation magnetization (M(s)) value can achieve 18.3 emu g(-1). The electrorheological (ER) effect was investigated using a suspension of the flower-like BaTiO3/Fe3O4 hierarchically structured particles dispersed in silicone oil. We can observe a slight shear-thinning behavior of shear viscosity at a low shear rate region even at zero applied electric field and a Newtonian fluid behavior at high shear rate regions.

  4. Facile synthesis, structure elucidation, and magnetic properties of perovskite BaTb{sub 1-x}Bi{sub x}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Farid, Muhammad Asim; Zhang, Hao; Li, Guobao; Liao, Fuhui; Lin, Jianhua [Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, 100871, Beijing (China); Yang, Aimei [College of Materials Science and Engineering, Guilin University of Technology, 541004, Guilin (China); Tian, Gengfang; Wu, Meimei [Neutron Scattering Laboratory, Department of Nuclear Physics, China Institute of Atomic Energy, 102413, Beijing (China)

    2017-03-17

    A series of perovskite BaTb{sub 1-x}Bi{sub x}O{sub 3} (0.0 ≤ x ≤ 0.25) solid solutions were synthesized by a typical solid-state method. Their structures were analyzed by a combination of X-ray diffraction, neutron diffraction, and selected-area electron diffraction. All of the materials crystalize in the P1 space group [a = 6.0582(1) Aa, b = 6.0473(1) Aa, c = 6.0693(1) Aa, α = 60.00(1) , β = 59.84(1) , γ = 60.06(1) for x = 0.0 at room temperature]. Magnetic measurements revealed that the magnetic-ordering temperature decreases with increasing Bi content in BaTb{sub 1-x}Bi{sub x}O{sub 3}; therefore, the presence of Bi decreases the magnetic interactions of Tb. Furthermore, the magnetic structure for BaTb{sub 1-x}Bi{sub x}O{sub 3} has been fully described in space group P1. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Magnetic properties of sulfur-doped graphene

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, J. [Department of Physics and Astronomy, Clemson University, Clemson, SC (United States); Clemson Nanomaterial Center, Clemson University, Clemson, SC (United States); Park, H. [Department of Physics, The Ohio State University, Columbus, OH (United States); Podila, R., E-mail: rpodila@g.clemson.edu [Department of Physics and Astronomy, Clemson University, Clemson, SC (United States); Clemson Nanomaterial Center, Clemson University, Clemson, SC (United States); COMSET, Clemson University, Clemson, SC (United States); Wadehra, A. [Department of Physics, The Ohio State University, Columbus, OH (United States); Ayala, P. [Faculty of Physics, University of Vienna, Vienna (Austria); Oliveira, L.; He, J. [Department of Physics and Astronomy, Clemson University, Clemson, SC (United States); Zakhidov, A.A.; Howard, A. [Alan G. MacDiarmid NanoTech Institute, The University of Texas at Dallas, Richardson, TX (United States); Wilkins, J. [Department of Physics, The Ohio State University, Columbus, OH (United States); Rao, A.M., E-mail: arao@g.clemson.edu [Department of Physics and Astronomy, Clemson University, Clemson, SC (United States); Clemson Nanomaterial Center, Clemson University, Clemson, SC (United States); COMSET, Clemson University, Clemson, SC (United States)

    2016-03-01

    While studying magnetism of d- and f-electron systems has been consistently an active research area in physics, chemistry, and biology, there is an increasing interest in the novel magnetism of p-electron systems, especially in graphene and graphene-derived nanostructures. Bulk graphite is diamagnetic in nature, however, graphene is known to exhibit either a paramagnetic response or weak ferromagnetic ordering. Although many groups have attributed this magnetism in graphene to defects or unintentional magnetic impurities, there is a lack of compelling evidence to pinpoint its origin. To resolve this issue, we systematically studied the influence of entropically necessary intrinsic defects (e.g., vacancies, edges) and extrinsic dopants (e.g., S-dopants) on the magnetic properties of graphene. We found that the saturation magnetization of graphene decreased upon sulfur doping suggesting that S-dopants demagnetize vacancies and edges. Our density functional theory calculations provide evidence for: (i) intrinsic defect demagnetization by the formation of covalent bonds between S-dopant and edges/vacancies concurring with the experimental results, and (ii) a net magnetization from only zig-zag edges, suggesting that the possible contradictory results on graphene magnetism in the literature could stem from different defect-types. Interestingly, we observed peculiar local maxima in the temperature dependent magnetizations that suggest the coexistence of different magnetic phases within the same graphene samples. - Highlights: • Magnetic properties of pristine and S-doped graphene were investigated. • Pristine graphene with intrinsic defects exhibits a non-zero magnetic moment. • The addition of S-dopants was found to quench the magnetic ordering. • DFT calculations confirmed that magnetization in graphene arises from defects. • DFT calculations show S-dopants quench local magnetic moment of defect structures.

  6. Magnetic properties of Ni(II)-Mn(III) LDHs

    Energy Technology Data Exchange (ETDEWEB)

    Giovannelli, F., E-mail: fabien.giovannelli@univ-tours.fr [LEMA, UMR 6157 CNRS-CEA, Universite Francois Rabelais, 3 place Jean Jaures, 41029 Blois (France); Zaghrioui, M.; Autret-Lambert, C. [LEMA, UMR 6157 CNRS-CEA, Universite Francois Rabelais, 3 place Jean Jaures, 41029 Blois (France); Delorme, F.; Seron, A. [BRGM, 3 Avenue Claude Guillemin, BP 36009, 45060 Orleans Cedex 2 (France); Chartier, T.; Pignon, B. [LEMA, UMR 6157 CNRS-CEA, Universite Francois Rabelais, 3 place Jean Jaures, 41029 Blois (France)

    2012-11-15

    The synthesis of Ni{sub 1-x}Mn{sub x}(OH){sub 2}(CO{sub 3}){sub x/2}{center_dot}nH{sub 2}O Layered Double Hydroxides (LDHs) for x = 0.2, 0.25 and 0.33, their characterisation by electron microscopy, X-ray diffraction and their magnetic properties are reported in this study. When x increases, the crystallinity of the nanoparticles is improved. The low temperature magnetic behaviour of these compounds is characteristic of the competition between in plane ferromagnetic and interlayer antiferromagnetic interactions. The ferromagnetism is due to in plane Ni cations interaction and decreases when manganese content increases (Tc decreases from 26 to 15 K when x increases from 0.2 to 0.33). It was found that the substitution of Ni by Mn ions favours the in plane antiferromagnetic order. This study demonstrates that magnetic interactions occur in LDH with non magnetic interlayer anions. -- Highlights: Black-Right-Pointing-Pointer The synthesis of Ni{sub 1-x}Mn{sub x}(OH){sub 2}(CO{sub 3}){sub x/2}{center_dot}nH{sub 2}O Layered Double Hydroxides have been performed. Black-Right-Pointing-Pointer The low temperature magnetic behaviour of these compounds has been studied. Black-Right-Pointing-Pointer The substitution of Ni by Mn ions favours the in plane antiferromagnetic order.

  7. SYNTHESES, SPECTROSCOPIC AND MAGNETIC PROPERTIES ...

    African Journals Online (AJOL)

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    suspension of II reacts with Mn(II), Ni(II), Cd(II), Fe(III) and UO2(VI) ions and ... There has been considerable interest in the synthesis and use of ... chelating abilities in recent years due to their practical convenience, operational flexibility and.

  8. Magnetic and Electrical Properties of Leachate

    Directory of Open Access Journals (Sweden)

    Kartika Kirana

    2011-11-01

    Full Text Available Heavy metals content as well as magnetic and electrical properties of leachate from Sarimukti, West Java were studied in an attempt to seek correlation between heavy metals content and magnetic/electrical properties. Such correlation is expected to open the way for the use of magnetic/electrical properties as proxy indicators for the concentration of heavy metals in the leachate. The number of leachate samples studied is 21; 15 were taken spatially at depth of 1 m while the remaining 6 samples were taken vertically at a particular point. Measurement results showed that the heavy metals content in the leachate has a smaller concentration, except for Fe. The correlation between magnetic susceptibility and heavy metals content was found to be not so significant. The best correlation coefficient between magnetic susceptibility with heavy metals in leachate was found in Zn. Correlation between electrical conductivity and heavy metal is also not so significant, except for Zn and Cd. The use of magnetic properties as proxy indicator for heavy metals content in leachate is plausible provided that the magnetic susceptibility exceeds certain threshold value. Correlation between magnetic susceptibility, electrical conductivity and heavy metal content would be good if each quantity has a large value.

  9. Synthesis and magnetic properties of a new borophosphate SrCo2BPO7 with a four-column ribbon structure.

    Science.gov (United States)

    Gou, Wenbin; He, Zhangzhen; Yang, Ming; Zhang, Weilong; Cheng, Wendan

    2013-03-04

    A new borophosphate SrCo2BPO7 is synthesized by a conventional high-temperature solid-state reaction. The titled compound is found to crystallize in monoclinic system with space group P21/c, which displays a distorted four-column ribbon structure. Both BO3 triangles and PO4 tetrahedra are isolated, while irregular triangles built by Co(2+) ions are found to exist between the connecting ribbons. Magnetic behaviors are investigated by means of susceptibility, magnetization, and heat capacity measurements. The results confirm that SrCo2BPO7 possesses a three-dimensional antiferromagnetic ordering at 25 K. The possible spin arrangements in the system are also suggested.

  10. Two new coordination polymers with flexible alicyclic carboxylate and bipyridyl co-ligands bearing trinuclear [Ni3(COO)6] SBUs: Synthesis, crystal structures, and magnetic properties

    Science.gov (United States)

    Zhu, Xian-Dong; Li, Yong; Gao, Jian-Gang; Wang, Fen-Hua; Li, Qing-Hai; Yang, Hong-Xun; Chen, Lei

    2017-02-01

    Two new coordination polymers generally formulated as [Ni3(Hchda)2(chda)2(bpy)2(H2O)2]n (1) and [Ni3(Hchda)2(chda)2(bpp)2(H2O)2]n (2) [H2chda = 1,1'-cyclohexanediacetic acid, bpy = 4,4'-bipyridine and bpp = 1,3-bis(4-pyridyl)propane], have been successfully assembled through mixed-ligands synthetic strategy with flexible alicyclic carboxylate and bipyridyl ligands. There structures feature trinuclear nickel secondary building units connected via the bridging bipyridyl spacers to form two-dimensional (4,4) grid layer. The nature of the different N-donor auxiliary ligands leads to the discrepancy in supramolecular structure of the two compounds. Magnetic studies indicate the ferromagnetic intra-complex magnetic interaction in the molecule for 1 and 2.

  11. Low-temperature synthesis, structural and magnetic properties of self-dopant LaMnO{sub 3+δ} nanoparticles from a metal-organic polymeric precursor

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Tokeer, E-mail: tahmad3@jmi.ac.in [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Lone, Irfan H.; Ubaidullah, Mohd. [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Coolhan, Kelsey [Department of Physics and Astronomy, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028 (United States)

    2013-11-15

    Graphical abstract: Monophasic and highly crystalline Self-dopant LaMnO{sub 3+δ} nanoparticles (72 nm) have been successfully synthesized at low temperature (773 K) by metal citrate complex method based on Pechini-type reaction route which showed ferromagnetic interaction. Surface areas of LaMnO{sub 3+δ} nanoparticles were found to be 157.4 and 153 m{sup 2} g{sup −1} for the samples annealed at 773 K and 1173 K, respectively. - Highlights: • Self-dopant LaMnO{sub 3+δ} nanoparticles using Pechini-type reaction route at 773 K. • Size range varies from 72 to 80 nm. • Surface area varies from 153 to 157 m{sup 2} g{sup −1}. • Extensive characterization using sophisticated techniques. - Abstract: Self-dopant LaMnO{sub 3+δ} nanoparticles have been successfully synthesized by metal citrate complex method based on Pechini-type reaction route, at low temperature (773 K). Powder X-ray diffraction and transmission electron microscope revealed pure and nanostructured phase of LaMnO{sub 3+δ} (δ = 0.125) with an average grain size of ∼72 nm (773 K) and ∼80 nm (1173 K). DC-magnetization measurements under an applied magnetic field of H = ±60 kOe showed an increase in the magnetization with the increase of calcination temperature. Ferromagnetic nature shown by non-stoichiometric LaMnO{sub 3+δ} was verified by well-defined hysteresis loop with large remanent magnetization (M{sub r}) and coercive field (H{sub c}). Surface areas of LaMnO{sub 3+δ} nanoparticles were found to be 157.4 and 153 m{sup 2} g{sup −1} for the samples annealed at 773 K and 1173 K, respectively.

  12. Topotactic synthesis, structure and magnetic properties of a new hexagonal polytype of silver cobaltate(III) AgCoO2+δ

    International Nuclear Information System (INIS)

    Muguerra, Herve; Colin, Claire; Anne, Michel; Julien, Marc-Henri; Strobel, Pierre

    2008-01-01

    A new form of delafossite-type AgCoO 2+δ was prepared using ion exchange from Na 0.75 CoO 2 in molten AgNO 3 -NH 4 NO 3 at 175 deg. C. Its structure was determined by the Rietveld refinement from X-ray powder diffraction measurements (XRD) data; it is hexagonal, space group P6 3 /mmc, a=2.871 and c=12.222 A. Its structure differs from previously reported AgCoO 2 (R3-barm, 3R polytype) by the stacking of Co-O layers; in the new phase, the 2H stacking of the precursor Na 0.75 CoO 2 is consistent with a topotactic ion exchange of Na by Ag. The new phase is found to contain a slight oxygen excess (δ=0.06). Magnetic susceptibility measurements show the absence of magnetic transition and a weak Curie term, consistent with the non-magnetic character of Co 3+ ions. - Graphical abstract: Comparison of the structures of high-temperature AgCoO 2 (left, 3R structure) and of new AgCoO 2+∂ (IE) (right, 6H structure). The latter is obtained topotactically from Na 0.7 CoO 2 by ion exchange in molten nitrates. Detailed studies showed that AgCoO 2+∂ (IE) is slightly over-stoichiometric in oxygen (∂=0.06)

  13. Topotactic synthesis, structure and magnetic properties of a new hexagonal polytype of silver cobaltate(III) AgCoO 2+δ

    Science.gov (United States)

    Muguerra, Hervé; Colin, Claire; Anne, Michel; Julien, Marc-Henri; Strobel, Pierre

    2008-11-01

    A new form of delafossite-type AgCoO 2+δ was prepared using ion exchange from Na 0.75CoO 2 in molten AgNO 3-NH 4NO 3 at 175 °C. Its structure was determined by the Rietveld refinement from X-ray powder diffraction measurements (XRD) data; it is hexagonal, space group P6 3/ mmc, a=2.871 and c=12.222 Å. Its structure differs from previously reported AgCoO 2 ( R3¯m, 3R polytype) by the stacking of Co-O layers; in the new phase, the 2H stacking of the precursor Na 0.75CoO 2 is consistent with a topotactic ion exchange of Na by Ag. The new phase is found to contain a slight oxygen excess ( δ=0.06). Magnetic susceptibility measurements show the absence of magnetic transition and a weak Curie term, consistent with the non-magnetic character of Co 3+ ions.

  14. Magnetic properties of singlet ground state systems

    International Nuclear Information System (INIS)

    Diederix, K.M.

    1979-01-01

    Experiments are described determining the properties of a magnetic system consisting of a singlet ground state. Cu(NO 3 ) 2 .2 1/2H 2 O has been studied which is a system of S = 1/2 alternating antiferromagnetic Heisenberg chains. The static properties, spin lattice relaxation time and field-induced antiferromagnetically ordered state measurements are presented. Susceptibility and magnetic cooling measurements of other compounds are summarised. (Auth.)

  15. Modeling of alkynes: synthesis and theoretical properties

    Directory of Open Access Journals (Sweden)

    Renato Rosseto

    2003-06-01

    Full Text Available In this paper we present the synthesis and simulation of alkynes derivatives. Semiempirical calculations were carried out for the ground and first excited states, including the spectroscopic properties of the absorption and emission (fluorescence and phosphorescence spectra by INDO/S-CI and DNdM-INDO/S-CI methods with geometries fully optimized by PM3/CI. The fact that the theoretical spectra are in accord with the experimental absorption spectra gives us a new possible approach on how structure modifications could affect the non-linear optical properties of alkynes.

  16. Synthesis and optical properties studies

    Directory of Open Access Journals (Sweden)

    N.A. El-Ghamaz

    2017-01-01

    Full Text Available 4-(4-Amino-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-ylideneamino-phenol (L1 and 4-(4-Amino-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-ylideneamino-benzoic acid (L2 have been synthesized by the condensation reaction of 4-aminoantipyrine (4-AAP and 4-aminophenol or 4-aminobenzoic acid in ethanolic solution and are characterized by various physico-chemical techniques. Thin films of L1 and L2 have been prepared by the conventional spin coating technique. X-ray diffraction patterns (XRD show an amorphous nature for both powder and thin films for L1 and L2 ligands. The optical absorption and refraction properties of L1 and L2 are investigated by spectrophotometric techniques at normal incidence of light in the wavelength range of 200–2500 nm. The absorption spectra show two peaks in the UV region which correspond to π → π∗ transition and a peak in UV–Vis region which may correspond to n → π∗ transition. The values of dispersion parameters Eo, Ed, εL, ε∞ and N/m* are calculated according to the single oscillator model. The presence of the OH group increases the value of ε∞ from 3.21 to 3.32 and the value of N/m* from 7.38 × 1053 to 2.08 × 1054 m−3Kg−1. The optical band transition is found to be indirect allowing fundamental energy gap values of 3.4 and 3.9 eV and onset energy gap values of 2.1 and 2.6 eV for L1 and L2, respectively.

  17. A simple aloe vera plant-extracted microwave and conventional combustion synthesis: Morphological, optical, magnetic and catalytic properties of CoFe2O4 nanostructures

    Science.gov (United States)

    Manikandan, A.; Sridhar, R.; Arul Antony, S.; Ramakrishna, Seeram

    2014-11-01

    Nanocrystalline magnetic spinel CoFe2O4 was synthesized by a simple microwave combustion method (MCM) using ferric nitrate, cobalt nitrate and Aloe vera plant extracted solution. For the comparative study, it was also prepared by a conventional combustion method (CCM). Powder X-ray diffraction, energy dispersive X-ray and selected-area electron diffraction results indicate that the as-synthesized samples have only single-phase spinel structure with high crystallinity and without the presence of other phase impurities. The crystal structure and morphology of the powders were revealed by high resolution scanning electron microscopy and transmission electron microscopy, show that the MCM products of CoFe2O4 samples contain sphere-like nanoparticles (SNPs), whereas the CCM method of samples consist of flake-like nanoplatelets (FNPs). The band gap of the samples was determined by UV-Visible diffuse reflectance and photoluminescence spectroscopy. The magnetization (Ms) results showed a ferromagnetic behavior of the CoFe2O4 nanostructures. The Ms value of CoFe2O4-SNPs is higher i.e. 77.62 emu/g than CoFe2O4-FNPs (25.46 emu/g). The higher Ms value of the sample suggest that the MCM technique is suitable for preparing high quality nanostructures for magnetic applications. Both the samples were successfully tested as catalysts for the conversion of benzyl alcohol. The resulting spinel ferrites were highly selective for the oxidation of benzyl alcohol and exhibit important difference among their activities. It was found that CoFe2O4-SNPs catalyst show the best performance, whereby 99.5% selectivity of benzaldehyde was achieved at close to 93.2% conversion.

  18. Superconducting property measuring system by magnetization method

    International Nuclear Information System (INIS)

    Ikisawa, K.; Mori, T.; Takasu, N.

    1988-01-01

    Superconducting property measuring system (CMS-370B) for high temperature oxide superconductor has been developed. This system adopts magnetization measurement. The superconducting properties are able to be measured automatically and continuously changing the temperature and external magnetic field. The critical current density as a function of temperature and magnetic field of high temperature superconductor YBa 2 Cu 3 O 7-y (YBCO) has been measured. This paper reports how it was confirmed that this system having the high performance and the accuracy gave the significant contribution to the superconducting material development

  19. Synthesis, crystal structure, and magnetic properties of quaternary iron selenides: Ba{sub 2}FePnSe{sub 5} (Pn=Sb, Bi)

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jian; Greenfield, Joshua T.; Kovnir, Kirill

    2016-10-15

    Two new barium iron pnictide–selenides, Ba{sub 2}FeSbSe{sub 5} and Ba{sub 2}FeBiSe{sub 5}, were synthesized by a high-temperature solid-state route and their crystal structures were determined using single crystal X-ray diffraction. Both compounds are isomorphic to the high pressure phase Ba{sub 3}FeS{sub 5} and crystallize in the orthorhombic space group Pnma (No. 62) with cell parameters of a=12.603(2)/12.619(2) Å, b=9.106(1)/9.183(1) Å, c=9.145(1)/9.123(1) Å and Z=4 for Ba{sub 2}FeSbSe{sub 5} and Ba{sub 2}FeBiSe{sub 5}, respectively. According to differential scanning calorimetry, Ba{sub 2}FePnSe{sub 5} compounds exhibit high thermal stability and melt congruently at 1055(5) K (Pn=Sb) and 1105(5) K (Pn=Bi). Magnetic characterizations reveal strong antiferromagnetic nearest-neighbor interactions in both compounds resulting in an antiferromagnetic ordering at 58(1) K for Ba{sub 2}FeSbSe{sub 5} and 79(2) K for Ba{sub 2}FeBiSe{sub 5}. The magnetic interactions between Fe{sup 3+} centers, which are at least 6 Å apart from each other, are mediated by superexchange interactions. - Graphical abstract: In Ba{sub 2}FeSbSe{sub 5} and Ba{sub 2}FeBiSe{sub 5} the magnetic interactions between Fe{sup 3+} centers, which are at least 6 Å apart from each other, are mediated by superexchange interactions. - Highlights: • New compounds Ba{sub 2}FeSbSe{sub 5} and Ba{sub 2}FeBiSe{sub 5} have been synthesized. • The crystal structure was determined by single crystal X-ray diffraction. • Both compounds melt congruently at temperatures above 1000 K. • Ba{sub 2}FeSbSe{sub 5} and Ba{sub 2}FeBiSe{sub 5} exhibit AFM ordering at 58 K (Sb) and 70 K (Bi). • Magnetic exchange between Fe{sup 3+} is mediated by either Se–Sb(Bi)–Se or Se–Ba–Se bridges.

  20. Properties of magnetically diluted nanocrystals prepared by mechanochemical route

    International Nuclear Information System (INIS)

    Balaz, P.; Skorvanek, I.; Fabian, M.; Kovac, J.; Steinbach, F.; Feldhoff, A.; Sepelak, V.; Jiang, J.; Satka, A.; Kovac, J.

    2010-01-01

    The bulk and surface properties of magnetically diluted Cd 0.6 Mn 0.4 S nanocrystals synthesized by solid state route in a planetary mill were studied. XRD, SEM, TEM (HRTEM), low-temperature N 2 sorption, nanoparticle size distribution as well as SQUID magnetometry methods have been applied. The measurements identified the aggregates of small nanocrystals, 5-10 nm in size. The homogeneity of produced particles with well developed specific surface area (15-66 m 2 g -1 ) was documented. The transition from the paramagnetic to the spin-glass-like phase has been observed below ∼40 K. The changes in the magnetic behaviour at low temperatures seem to be correlated with the formation of the new surface area as a consequence of milling. The magnetically diluted Cd 0.6 Mn 0.4 S nanocrystals are obtained in the simple synthesis step, making the process attractive for industrial applications.

  1. Dynamical properties of unconventional magnetic systems

    International Nuclear Information System (INIS)

    Helgesen, G.

    1997-05-01

    The Advanced Study Institute addressed the current experimental and theoretical knowledge of the dynamical properties of unconventional magnetic systems including low-dimensional and mesoscopic magnetism, unconventional ground state, quantum magnets and soft matter. The main approach in this Advanced Study Institute was to obtain basic understanding of co-operative phenomena, fluctuations and excitations in the wide range unconventional magnetic systems now being fabricated or envisioned. The report contains abstracts for lectures, invited seminars and posters, together with a list of the 95 participants from 24 countries with e-mail addresses

  2. Synthesis and magnetic properties of Co.sub.1-x./sub.Zn.sub.x./sub.Fe.sub.2./sub.O.sub.4+γ./sub. nanoparticles as materials for magnetic fluid hyperthermia

    Czech Academy of Sciences Publication Activity Database

    Veverka, Miroslav; Veverka, Pavel; Jirák, Zdeněk; Kaman, Ondřej; Knížek, Karel; Maryško, Miroslav; Pollert, Emil; Závěta, Karel

    2010-01-01

    Roč. 322, č. 16 (2010), s. 2386-2389 ISSN 0304-8853 R&D Projects: GA AV ČR KAN200200651; GA AV ČR KJB100100701; GA MŠk MEB090901 Institutional research plan: CEZ:AV0Z10100521 Keywords : magnetic nanoparticle * cobalt zinc ferrite * precipitation * magnetic behavior * magnetic fluid hyperthermia Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.689, year: 2010

  3. Magnetic properties of partially oxidized Fe films

    Science.gov (United States)

    Garcia, Miguel Angel; Lopez-Dominguez, Victor; Hernando, Antonio

    Hybrid magnetic nanostructures exhibit appealing properties due to interface and proximity effects. A simple and interesting system of hybrid magnetic nanomaterials are partially oxidized ferromagnetic films. We have fabricated Fe films by thermal evaporation and performed a partial oxidation to magnetite (Fe3O4) by annealing in air at different times and temperatures. The magnetic properties of the films evolve from those of pure metallic iron to pure magnetite, showing intermediate states where the proximity effects control the magnetic behavior. At some stages, the magnetization curves obtained by SQUID and MOKE magnetometry exhibit important differences due to the dissimilar contribution of both phases to the magneto-optical response of the system This work has been supported by the Ministerio Español de Economia y Competitividad (MINECO) MAT2013-48009-C4-1. V.L.D and M.A.G. acknowledges financial support from BBVA foundation.

  4. SYNTHESIS of MOLECULE/POLYMER-BASED MAGNETIC MATERIALS

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Joel S. [Univ. of Utah, Salt Lake City, UT (United States)

    2016-02-01

    We have synthesized and characterized several families of organic-based magnets, a new area showing that organic species can exhibit the technologically important property of magnetic ordering. Thin film magnets with ordering temperatures exceeding room temperature have been exceeded. Hence, organic-based magnets represent a new class of materials that exhibit magnetic ordering and do not require energy-intensive metallurgical processing and are based upon Earth-abundant elements.

  5. Synthesis, Spectroscopy, Thermal Analysis, Magnetic Properties and Biological Activity Studies of Cu(II and Co(II Complexes with Schiff Base Dye Ligands

    Directory of Open Access Journals (Sweden)

    Saeid Amani

    2012-05-01

    Full Text Available Three azo group-containing Schiff base ligands, namely 1-{3-[(3-hydroxy-propyliminomethyl]-4-hydroxyphenylazo}-4-nitrobenzene (2a, 1-{3-[(3-hydroxypropyl-iminomethyl]-4-hydroxyphenylazo}-2-chloro-4-nitrobenzene (2b and 1-{3-[(3-hydroxy-propyliminomethyl]-4-hydroxyphenylazo}-4-chloro-3-nitrobenzene (2c were prepared. The ligands were characterized by elemental analysis, FTIR spectroscopy, UV-Vis spectroscopy, 13C- and 1H-NMR spectroscopy and thermogravimetric analysis. Next the corresponding copper(II and cobalt(II metal complexes were synthesized and characterized by the physicochemical and spectroscopic methods of elemental analysis, FTIR spectroscopy, UV-Vis spectroscopy, magnetic moment measurements, and thermogravimetric analysis (TGA and (DSC. The room temperature effective magnetic moments of complexes are 1.45, 1.56, 1.62, 2.16, 2.26 and 2.80 B.M. for complexes 3a, 3b, 3c, 4a 4b, and 4c, respectively, indicating that the complexes are paramagnetic with considerable electronic communication between the two metal centers.

  6. Ultrathin magnetic structures II measurement techniques and novel magnetic properties

    CERN Document Server

    Heinrich, Bretislav

    2006-01-01

    The ability to understand and control the unique properties of interfaces has created an entirely new field of magnetism, with profound impact in technology and serving as the basis for a revolution in electronics. Our understanding of the physics of magnetic nanostructures has also advanced significantly. This rapid development has generated a need for a comprehensive treatment that can serve as an introduction to the field for those entering it from diverse fields, but which will also serve as a timely overview for those already working in this area. The four-volume work Ultra-Thin Magnetic

  7. Synthesis, structure and magnetic property of a two-dimensional coordination polymer decorated with sine wave-like 1D double chain

    Science.gov (United States)

    Yao, Xiao-Qiang; Li, Dan-Yang; Xiao, Guo-Bin; Ma, Heng-Chang; Lei, Zi-Qiang; Liu, Jia-Cheng

    2018-04-01

    A new compound, {[Co(BPFI)(NDC)]H2O·0.5DMF}n (1) has been synthesized under hydrothermal condition by the self-assembly of V-shaped N-containing rigid ligand BPFI with Co(II) ions in the presence of H2NDC acid, where BPFI = 2,8-di(1H-imidazole-1-yl)dibenzo[b,d]furan, H2NDC = naphthalene-1,4-dicarboxylic acid. Compound 1 was characterized by elemental analysis, single crystal X-ray diffraction, FT-IR spectroscopy and UV-visible spectra. Structural analysis reveals that compound 1 is a unique dinuclear Co-based 2D (4,4) layer structure decorated with parallel double chains. In addition, magnetic study reveals the existence of antiferromagnetic coupling interactions between the Co(II) ions within the dinuclear unit of 1.

  8. Uranium hetero-bimetallic complexes: synthesis, structure and magnetic properties; Complexes heterobimetalliques de l'uranium: synthese, structure et proprietes magnetiques

    Energy Technology Data Exchange (ETDEWEB)

    Le Borgne, Th

    2000-10-04

    The aim of this thesis is to synthesize molecular complexes with uranium and transition metal ions in close proximity, to determine the nature of the magnetic interaction between them. We decided to use Schiff bases as assembling ligands, which are unusual for uranium (IV). Although the simplest Schiff bases, such as H{sub 2}Salen, lead to ligand exchange reactions, the bi-compartmental Schiff base H{sub 4}L{sup 6} (bis(3-hydroxy-salicylidene) - 2,2-dimethyl-propylene) allows the crystal structure determination of the complex [L{sup 6}Cu(pyr)]U[L{sup 6}Cu].2pyr, obtained by reaction of the metallo-ligand H{sub 2}L{sup 6}Cu with U(acac){sub 4}. In this manner, the complexes [L{sup 6}Co(pyr)]{sub 2}U and [L{sup 6}Ni(pyr)]{sub 2}U.pyr were also isolated, as well as the compounds in which the paramagnetic ions have been exchanged by the diamagnetic ions Zn{sup II}, Zr{sup IV} and Th{sup IV}': [L{sup 6}Zn(pyr)]{sub 2}U, [L{sup 6}Cu]{sub 2}Zr and [L{sup 6}Cu(pyr)]Th[L{sup 6}Cu].2pyr. These complexes are the first which involve three metallic centres assembling by the means of a hexa-dentate Schiff base. The crystalline structures show, for all these complexes, the outstanding orthogonal arrangement of the two fragments L{sup 6}M around the central atom which is in a dodecahedral environment of eight oxygen atoms of two Schiff bases. The syntheses of the isostructural complexes Cu2{sup II} and Zn{sub 2}U in which the uranium (IV) ion is close, in the first one, to the paramagnetic ion Cu{sup II} and, in the second one, to the diamagnetic ion Zn{sup II}, has allowed the use of the empiric method to determine the nature of the magnetic interaction between an f element and a transition metal. The comparison of the magnetic behaviour of two complexes Cu{sub 2}U and Zn{sub 2}U, expressed by the variation of {chi}T vs T, reveals the ferromagnetic interaction in the heart of the triad Cu-U-Cu. The magnetic behaviour of the complexes Cu{sub 2}Th et Cu{sub 2}Zr which does not

  9. Synthesis and bio-applications of targeted magnetic-fluorescent composite nanoparticles

    International Nuclear Information System (INIS)

    Xia, Hui; Tong, Ruijie; Song, Yanling; Xiong, Fang; Li, Jiman; Wang, Shichao; Fu, Huihui; Wen, Jirui; Li, Dongze; Zeng, Ye; Zhao, Zhiwei; Wu, Jiang

    2017-01-01

    Magnetic-fluorescent nanoparticles have a tremendous potential in biology. As the benefits of these materials gained recognition, increasing attention has been given to the conjugation of magnetic-fluorescent nanoparticles with targeting ligands. The magnetic and fluorescent properties of nanoparticles offer several functionalities, including imaging, separation, and visualization, while the presence of a targeting ligand allows for selective cell and tissue targeting. In this review, methods for the synthesis of targeted magnetic-fluorescent nanoparticles are explored, and recent applications of these nanocomposites to the detection and separation of biomolecules, fluorescent and magnetic resonance imaging, and cancer diagnosis and treatment will be summarized. As these materials are further optimized, targeted magnetic-fluorescent nanoparticles hold great promise for the diagnosis and treatment of some diseases.

  10. Synthesis and bio-applications of targeted magnetic-fluorescent composite nanoparticles

    Science.gov (United States)

    Xia, Hui; Tong, Ruijie; Song, Yanling; Xiong, Fang; Li, Jiman; Wang, Shichao; Fu, Huihui; Wen, Jirui; Li, Dongze; Zeng, Ye; Zhao, Zhiwei; Wu, Jiang

    2017-04-01

    Magnetic-fluorescent nanoparticles have a tremendous potential in biology. As the benefits of these materials gained recognition, increasing attention has been given to the conjugation of magnetic-fluorescent nanoparticles with targeting ligands. The magnetic and fluorescent properties of nanoparticles offer several functionalities, including imaging, separation, and visualization, while the presence of a targeting ligand allows for selective cell and tissue targeting. In this review, methods for the synthesis of targeted magnetic-fluorescent nanoparticles are explored, and recent applications of these nanocomposites to the detection and separation of biomolecules, fluorescent and magnetic resonance imaging, and cancer diagnosis and treatment will be summarized. As these materials are further optimized, targeted magnetic-fluorescent nanoparticles hold great promise for the diagnosis and treatment of some diseases.

  11. Synthesis and bio-applications of targeted magnetic-fluorescent composite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Hui; Tong, Ruijie [Sichuan University, West China Medical Center (China); Song, Yanling [Shenyang University of Chemical Technology, College of Pharmaceutical and Biological Engineering (China); Xiong, Fang [Sichuan University, West China College of Stomatology (China); Li, Jiman [Sichuan Cancer Hospital, Pathology Department (China); Wang, Shichao; Fu, Huihui; Wen, Jirui; Li, Dongze; Zeng, Ye; Zhao, Zhiwei, E-mail: zzw2002400@126.com; Wu, Jiang, E-mail: jw@scu.edu.cn [Sichuan University, West China Medical Center (China)

    2017-04-15

    Magnetic-fluorescent nanoparticles have a tremendous potential in biology. As the benefits of these materials gained recognition, increasing attention has been given to the conjugation of magnetic-fluorescent nanoparticles with targeting ligands. The magnetic and fluorescent properties of nanoparticles offer several functionalities, including imaging, separation, and visualization, while the presence of a targeting ligand allows for selective cell and tissue targeting. In this review, methods for the synthesis of targeted magnetic-fluorescent nanoparticles are explored, and recent applications of these nanocomposites to the detection and separation of biomolecules, fluorescent and magnetic resonance imaging, and cancer diagnosis and treatment will be summarized. As these materials are further optimized, targeted magnetic-fluorescent nanoparticles hold great promise for the diagnosis and treatment of some diseases.

  12. Mild hydrothermal synthesis, crystal structure, thermal behaviour, spectroscopic and magnetic properties of (NH4)0.80Li0.20[Fe(AsO4)F

    International Nuclear Information System (INIS)

    Berrocal, Teresa; Mesa, Jose L.; Larrea, Edurne S.; Bazan, Begona; Pizarro, Jose L.; Lezama, Luis; Rojo, Teofilo; Arriortua, Maria I.

    2011-01-01

    The (NH 4 ) 0.80 Li 0.20 [Fe(AsO 4 )F] compound has been synthesized under mild hydrothermal conditions. The compound crystallize in the orthorhombic Pna2 1 space group, with cell parameters a=13.352(9), b=6.7049(9), c=10.943(2) A and Z=8. The compound belongs to the KTiO(PO 4 ) structure type, with chains alternating FeO 4 F 2 octahedra and AsO 4 tetrahedra, respectively, running along the 'a' and 'b' crystallographic axes. The diffuse reflectance spectrum in the visible region shows the forbidden electronic transitions characteristic of the Fe(III) d 5 -high spin cation in slightly distorted octahedral geometry. The Moessbauer spectrum at room temperature is characteristic of iron (III) cations. The ESR spectra, carried out from room temperature to 200 K, remain isotropic with variation in temperature; the g-value being 1.99(1). Magnetic measurements indicate the predominance of strong antiferromagnetic interactions. - Graphical Abstract: Three-dimensional structure of (NH 4 ) 0.80 Li 0.20 [Fe(AsO 4 )F], a fluoroarsenate containing lithium and ammonium in the structural cavities. Highlights: → (NH 4 ) 0.80 Li 0.20 [Fe(AsO 4 )F] has been synthesized by mild hydrothermal technique. → The compound exhibits a three-dimensional structure. → Moessbauer spectrum indicates the existence of Fe(III) cations. → Visible spectroscopy confirms the hexacoordination of Fe(III). → Magnetic measurements indicate the existence of a global antiferromagnetic ordering.

  13. Synthesis and characterization of ultrafine well-dispersed magnetic nanoparticles

    International Nuclear Information System (INIS)

    Liu, Z.L.; Wang, H.B.; Lu, Q.H.; Du, G.H.; Peng, L.; Du, Y.Q.; Zhang, S.M.; Yao, K.L.

    2004-01-01

    Ultrafine well-dispersed magnetic nanoparticles were directly prepared in aqueous solution using controlled coprecipitation method. The structure, size, size distributions and magnetic properties of the magnetic nanoparticles, characterized by TEM, XRD and VSM, indicated the formation of single domain nanoparticles with average size smaller than 5 nm. The magnetic nanoparticles show superparamagnetism and a lower saturation magnetization is found as a consequence of smaller particle size. The relevant conditions for obtaining these magnetic colloids are discussed and the so-prepared magnetic nanoparticles are stable in a wide pH range

  14. Tailoring the magnetic properties of cobalt-ferrite nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Vega, A. Estrada de la; Garza-Navarro, M. A., E-mail: marco.garzanr@uanl.edu.mx; Durán-Guerrero, J. G.; Moreno Cortez, I. E.; Lucio-Porto, R.; González-González, V. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica (Mexico)

    2016-01-15

    In this contribution, we report on the tuning of magnetic properties of cobalt-ferrite nanoclusters. The cobalt-ferrite nanoclusters were synthesized from a two-step approach that consists of the synthesis of cobalt-ferrite nanoparticles in organic media, followed by their dispersion into aqueous dissolution to form an oil-in-water emulsion. These emulsions were prepared at three different concentrations of the cationic surfactant cetyltrimethylammonium bromide (CTAB), in order to control the size and clustering density of the nanoparticles in the nanoclusters. The synthesized samples were characterized by transmission electron microscopy and their related techniques, such as bright-field and Z-contrast imaging, electron diffraction and energy-dispersive X-ray spectrometry; as well as static magnetic measures. The experimental evidence indicates that the size, morphology, and nanoparticles clustering density in the nanoclusters is highly dependent of the cobalt-ferrite:CTAB molar ratio that is used in their synthesis. In addition, due to the clustering of the nanoparticles into the nanoclusters, their magnetic moments are blocked to relax cooperatively. Hence, the magnetic response of the nanoclusters can be tailored by controlling the size and nanoparticles clustering density.

  15. Synthesis, structure and magnetic properties of cobalt(II) and copper(II) coordination polymers assembled by phthalate and 4-methylimidazole

    International Nuclear Information System (INIS)

    Baca, S.G.; Malinovskii, S.T.; Franz, Patrick; Ambrus, Christina; Stoeckli-Evans, Helen; Gerbeleu, Nicolae; Decurtins, Silvio

    2004-01-01

    New coordination polymers [M(Pht)(4-MeIm) 2 (H 2 O)] n (M=Co (1), Cu (2); Pht 2- =dianion of o-phthalic acid; 4-MeIm=4-methylimidazole) have been synthesized and characterized by IR spectroscopy, X-ray crystallography, thermogravimetric analysis and magnetic measurements. The crystal structures of 1 and 2 are isostructural and consist of [M(4-MeIm) 2 (H 2 O)] building units linked in infinite 1D helical chains by 1,6-bridging phthalate ions which also act as chelating ligands through two O atoms from one carboxylate group in the case of 1. In complex 1, each Co(II) atom adopts a distorted octahedral N 2 O 4 geometry being coordinated by two N atoms from two 4-MeIm, three O atoms of two phthalate residues and one O atom of a water molecule, whereas the square-pyramidal N 2 O 3 coordination of the Cu(II) atom in 2 includes two N atoms of N-containing ligands, two O atoms of two carboxylate groups from different Pht, and a water molecule. An additional strong O-H↑··O hydrogen bond between a carboxylate group of the phthalate ligand and a coordinated water molecule join the 1D helical chains to form a 2D network in both compounds. The thermal dependences of the magnetic susceptibilities of the polymeric helical Co(II) chain compound 1 were simulated within the temperature range 20-300 K as a single ion case, whereas for the Cu(II) compound 2, the simulations between 25 and 300 K, were made for a linear chain using the Bonner-Fisher approximation. Modelling the experimental data of compound 1 with MAGPACK resulted in: g=2.6, vertical bar D vertical bar=62 cm -1 . Calculations using the Bonner-Fisher approximation gave the following result for compound 2: g=2.18, J=-0.4 cm -1

  16. Synthesis of zinc substituted cobalt ferrites via reverse micelle technique involving in situ template formation: A study on their structural, magnetic, optical and catalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Charanjit; Jauhar, Sheenu [Department of Chemistry, Panjab University, Chandigarh 160014 (India); Kumar, Vinod [ICON Analytical Equipment (P) Ltd., Mumbai 400018 (India); Singh, Jagdish [Institute Instrumentation Centre, Indian Institute of Technology–Roorkee (India); Singhal, Sonal, E-mail: sonal1174@gmail.com [Department of Chemistry, Panjab University, Chandigarh 160014 (India)

    2015-04-15

    Nano-crystalline particles of visible light responsive Zn–Co ferrites having formula Zn{sub x}Co{sub 1-x}Fe{sub 2}O{sub 4} (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) were successfully synthesized via reverse micelle technique. Sodium dodecyl sulfate was used as a surfactant/templating agent. The ferrite formation was confirmed using powder X-Ray Diffraction (XRD) and Fourier Transform Infrared (FT-IR) spectroscopy. The spherical shape of the ferrite particles was established by High Resolution Transmission Electron Microscope (HR-TEM) analysis. From the magnetic studies, the ferromagnetic nature of CoFe{sub 2}O{sub 4} was known. However, the nano-particles exhibited a transition from ferromagnetic to super-paramagnetic upon increasing the zinc concentration. In addition, the photo-Fenton activity of ferrites was also studied by carrying out degradation of Rhodamine B (RhB) dye under visible light irradiation. The catalytic activity increased with increase in zinc ion concentration. - Highlights: • Controlled dimensions of Zn–Co ferrite nanoparticles by microemulsion technique. • Spherical shape with uniform size distribution of ∼5 nm was achieved. • Significant shift from ferromagnetic to superparamagnetic with Zn{sup 2+} ion doping. • Improved photocatalytic activity with Zn{sup 2+} ion doping.

  17. Synthesis, crystal structure, and magnetic properties of pyrochlore-type Eu{sub 2}Ta{sub 2}(O,N){sub 7+δ}

    Energy Technology Data Exchange (ETDEWEB)

    Anke, Bjoern; Hund, Sophie; Lorent, Christian; Lerch, Martin [Institut fuer Chemie, Technische Universitaet Berlin (Germany); Janka, Oliver; Block, Theresa; Poettgen, Rainer [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster (Germany)

    2017-12-13

    Pyrochlore-type Eu{sub 2}Ta{sub 2}(O,N){sub 7+δ} phases were prepared by reaction of ammonia with an amorphous europium tantalum oxide precursor. {sup 151}Eu Moessbauer and EPR spectroscopy as well as magnetic susceptibility measurements point to the presence of exclusively Eu{sup 3+}. For phase-pure samples (X-ray powder diffraction), the nitrogen content varies between 1.0 and 1.8 wt %, leading to compositions in the range Eu{sub 2}Ta{sub 2}O{sub 7.1}N{sub 0.6} - Eu{sub 2}Ta{sub 2}O{sub 6.5}N{sub 1.0}. Pyrochlore-type phases are structurally derived from the fluorite type with 1/8 of the anions missing, resulting in an ideal composition A{sub 2}B{sub 2}X{sub 7}. In Eu{sub 2}Ta{sub 2}(O,N){sub 7+δ} the excess anions partly occupy these vacancies. The prepared phases are colorless with a direct optical bandgap of 4.3 eV and they show the typical Van Vleck paramagnetic behavior known for trivalent Eu atoms. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Synthesis, Crystal Structure, and Magnetic Properties of Giant Unit Cell Intermetallics R117Co52+δSn112+γ (R = Y, La, Pr, Nd, Ho

    Directory of Open Access Journals (Sweden)

    Ping Chai

    2016-12-01

    Full Text Available Ternary intermetallics R117Co52+δSn112+γ (R = Y, La, Pr, Nd, and Ho have been prepared by arc-melting followed by annealing at 800 °C. All the compounds belong to the Tb117Fe52Ge112 structure type (space group Fm 3 ¯ m characterized by a complex giant cubic unit cell with a ~ 30 Å. The single-crystal structure determination of Y- and La-containing compounds reveals a significant structural disorder. A comparison of these and earlier reported crystal structures of R117Co52+δSn112+γ suggests that more extensive disorder occurs for structures that contain larger lanthanide atoms. This observation can be explained by the need to maintain optimal bonding interactions as the size of the unit cell increases. Y117Co56Sn115 exhibits weak paramagnetism due to the Co sublattice and does not show magnetic ordering in the 1.8–300 K range. Ho117Co55Sn108 shows ferromagnetic ordering at 10.6 K. Both Pr117Co54Sn112 and Nd117Co54Sn111 exhibit antiferromagnetic ordering at 17 K and 24.7 K, respectively, followed by a spin reorientation transition at lower temperature.

  19. Influence of pH and fuels on the combustion synthesis, structural, morphological, electrical and magnetic properties of CoFe{sub 2}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Shanmugavani, A. [Solid State Ionics and Energy Devices Laboratory, Department of Physics, Bharathiar University, Coimbatore 641 046 (India); Selvan, R.Kalai, E-mail: selvankram@buc.edu.in [Solid State Ionics and Energy Devices Laboratory, Department of Physics, Bharathiar University, Coimbatore 641 046 (India); Layek, Samar [Department of Physics, Indian Institute of Technology, Kanpur 208016 (India); Vasylechko, Leonid [Semiconductor Electronics Department, Lviv Polytechnic National University, 12 Bandera Street, Lviv 79013 (Ukraine); Sanjeeviraja, C. [Department of Physics, Alagappa Chettiar College of Engineering and Technology, Karaikudi 630 004 (India)

    2015-11-15

    Nanocrystalline spinel cobalt ferrite particles are synthesized by simple combustion method using aspartic acid and glycine as fuels. The single phase cubic structure of CoFe{sub 2}O{sub 4} is revealed through X-ray diffraction analysis (XRD). Further the Rietveld refinement confirms the formation of inverse spinel structure of CoFe{sub 2}O{sub 4}. The characteristic functional groups of Co–O and Fe–O are identified from Fourier Transform Infrared (FT-IR) analysis. Uniform distribution of of nearly spherical particles with the size range of 40–80 nm is identified through field emission scanning electron microscope (FESEM) images. The calculated DC conductivity is 1.469 × 10{sup −7} and 2.214 × 10{sup −8} S cm{sup −1}, for CoFe{sub 2}O{sub 4} synthesized using aspartic acid and glycine, respectively. The dielectric behavior obeys the Maxwell–Wagner interfacial polarization. The ferromagnetic behavior of CoFe{sub 2}O{sub 4} is identified using VSM analysis and the calculated coercivity is 27 Oe and saturation magnetization is 68 emu/g.

  20. Polymorphism and pressure driven thermal spin crossover phenomenon in [Fe(abpt) sub 2 (NCX) sub 2] (X = S, and Se): synthesis, structure and magnetic properties

    CERN Document Server

    Gaspar, A B; Real, J R; Muñoz, M C; Ksenofontov, V; Guetlich, P; Levchenko, G G

    2003-01-01

    The monomeric compounds [Fe(abpt) sub 2 (NCX) sub 2] (X= S (1), Se (2) and abpt 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole) have been synthesized and characterized. They crystallize in the monoclinic P2 sub 1 /n space group with a 11.637(2) Aa, b = 9.8021(14) Aa, c = 12.983 8(12) Aa, beta = 101.126(14) sup o , and Z= 2 for 1, and a = 11.601(2) Aa, b = 9.6666 (14) Aa, c = 12.883(2) Aa, beta = 101.449(10) sup o , and Z= 2 for 2. The unit cell contains a pair mononuclear [Fe(abpt) sub 2 (NCX) sub 2] units related by a center of symmetry. Each iron atom, located at a molecular inversion center, is in a distorted octahedral environment. Four of the six nitrogen atoms coordinated to the Fe(11) ion belong to the pyridine-N(1) and triazole-N (2) rings of two abpt ligands. The remaining trans positions are occupied by two nitrogen atoms, N(3), belonging to the two pseudo-halide ligands. The magnetic susceptibility measurements at ambient pressure have revealed that they are in the high-spin range in the 2 K-300 K te...

  1. Magnetic properties of sheet silicates

    International Nuclear Information System (INIS)

    Ballet, O.; Coey, J.M.D.

    1982-01-01

    Susceptibility, magnetisation and Moessbauer measurements are reported for a representative selection of 2:1 layer phyllosilicates. Eight samples from the mica, vermiculite and smectite groups include examples diluted in iron which are paramagnetic at all temperatures, as well as iron-rich silicates which order magnetically below 10 K. Anisotropic susceptibility of crystals of muscovite, biotite and vermiculite is quantitatively explained with a model where the Fe 2+ ions lie in sites of effective trigonal symmetry, the trigonal axis lying normal to the sheets. The ferrous ground state is an orbital singlet. Ferric iron gives an isotropic contribution to the susceptibility. Fe 2+ -Fe 2+ exchange interactions are ferromagnetic with Gapprox. equal to2 K, whereas Fe 3+ -Fe 3+ coupling is antiferromagnetic in the purely ferric minerals. A positive paramagnetic Curie temperature for glauconite may be attributable to Fe 2+ → Fe 3+ charge transfer. Magnetic order was found to set in inhomogeneously for glauconite at 1-7 K. One biotite sample showed an antiferromagnetic transition at Tsub(N) = 7 K marked by a well-defined susceptibility maximum. Its magnetic structure, consisting of ferromagnetic sheets with moments in their planes coupled antiferromagnetically by other, weak interactions, resembles that found earlier for the 1:1 mineral greenalite. (orig.)

  2. Magnetic self-assembly for the synthesis of magnetically exchange coupled MnBi/Fe–Co composites

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Xia [Department of Chemical and Biological Engineering and MINT Center, The University of Alabama, Tuscaloosa, AL 35487 (United States); Hong, Yang-Ki, E-mail: ykhong@eng.ua.edu [Department of Electrical and Computer Engineering and MINT Center, The University of Alabama, Tuscaloosa, AL 35487 (United States); Park, Jihoon; Lee, Woncheol [Department of Electrical and Computer Engineering and MINT Center, The University of Alabama, Tuscaloosa, AL 35487 (United States); Lane, Alan M. [Department of Chemical and Biological Engineering and MINT Center, The University of Alabama, Tuscaloosa, AL 35487 (United States); Cui, Jun [Energy and Environment Directorate, Pacific Northwestern National Laboratory, Richland, WA 99354 (United States)

    2015-11-15

    Exchange coupled hard/soft MnBi/Fe–Co core/shell structured composites were synthesized using a magnetic self-assembly process. MnBi particles were prepared by arc-melting, and Fe–Co nanoparticles were synthesized by an oleic acid assisted chemical reduction method. Grinding a mixture of micron-sized MnBi and Fe–Co nanoparticles in hexane resulted in MnBi/Fe–Co core/shell structured composites. The MnBi/Fe–Co (95/5 wt%) composites showed smooth magnetic hysteresis loops, enhanced remanent magnetization, and positive values in the ΔM curve, indicating exchange coupling between MnBi and Fe–Co particles. - Graphical abstract: Both MnBi and Fe–Co particles were dispersed in hexane for grinding. Because of the oleic acid used during the Fe–Co nanoparticle synthesis, they could be well dispersed in hexane. During the grinding, the size of MnBi particles was decreased, hexane was evaporated, and the Fe–Co nanoparticles were concentrated in the solvent and magnetically attracted by MnBi particles, forming a core/shell structure. - Highlights: • Exchange coupled MnBi/Fe–Co composites are synthesized through magnetic selfassembly. • Magnetic exchange coupling is demonstrated by smooth magnetic hysteresis loops, enhanced remanent magnetization, and dominant positive peak in the ΔM curve. • The experimental results in magnetic properties are close to the theoretical calculation results.

  3. Graphene optoelectronics synthesis, characterization, properties, and applications

    CERN Document Server

    bin M Yusoff, Abdul Rashid

    2014-01-01

    This first book on emerging applications for this innovative material gives an up-to-date account of the many opportunities graphene offers high-end optoelectronics.The text focuses on potential as well as already realized applications, discussing metallic and passive components, such as transparent conductors and smart windows, as well as high-frequency devices, spintronics, photonics, and terahertz devices. Also included are sections on the fundamental properties, synthesis, and characterization of graphene. With its unique coverage, this book will be welcomed by materials scientists, solid-

  4. Magnetic Properties of Electrically Contacted Fe4 Molecular Magnets

    Science.gov (United States)

    Burgess, Jacob; Malavolti, Luigi; Lanzilotto, Valeria; Mannini, Matteo; Totti, Frederico; Ninova, Silviya; Yan, Shichao; Choi, Deung-Jang; Rolf-Pissarczyk, Steffen; Cornia, Andrea; Sessoli, Roberta; Loth, Sebastian

    2015-03-01

    Single molecule magnets (SMMs) are often large and fragile molecules. This poses challenges for the construction of SMM based spintronics. Device geometries with two electronic leads contacting a molecule may be explored via scanning tunneling microscopy (STM). The Fe4 molecule stands out as a robust, thermally evaporable SMM, making it ideal for such an experiment. Here we present the first STM investigations of individual Fe4 molecules thermally evaporated onto a monolayer of Cu2N on a Cu (100) crystal. Using inelastic electron tunneling spectroscopy (IETS), spin excitations in single Fe4 molecules can be detected at meV energies. Analysis using a Spin Hamiltonian allows extraction of magnetic properties of individual Fe4 molecules, and investigation of the influence of the electronic leads. The tip and sample induce small changes in the magnetic properties of Fe4 molecules, making Fe4 a promising candidate for the development of spintronics devices based on SMMs.

  5. Properties of magnetic nano-particles

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1997-01-01

    The intrinsic thermodynamic magnetic properties of clusters are discussed using spin wave theory for a Heisenberg model, with a fixed magnitude of the spins S-i = S and site independent nearest neighbor exchange interaction. The consequences of the more realistic Hubbard model is considered...... in which we allow for a magnetization profile at T = 0 and a structural relaxation, which in turn will give rise to a site dependent exchange interaction. Et is concluded that correlation effects among the electrons play a very important role in small clusters, albeit not modifying the thermodynamic...... properties drastically. The finite cluster size gives foremost rise to a discrete excitation spectrum with a large energy gap to the ground state. The relaxation of the magnetization during the reversal of the external magnetic field is discussed. A first step towards a quantitative understanding...

  6. Three-dimensional magnetic properties of soft magnetic composite materials

    International Nuclear Information System (INIS)

    Lin, Z.W.; Zhu, J.G.

    2007-01-01

    A three-dimensional (3-D) magnetic property measurement system, which can control the three components of the magnetic flux density B vector and measure the magnetic field strength H vector in a cubic sample of soft magnetic material, has been developed and calibrated. This paper studies the relationship between the B and H loci in 3-D space, and the power losses features of a soft magnetic composite when the B loci are controlled to be circles with increasing magnitudes and ellipses evolving from a straight line to circle in three orthogonal planes. It is found that the B and H loci lie in the same magnetization plane, but the H loci and power losses strongly depend on the orientation, position, and process of magnetization. On the other hand, the H vector evolves into a unique locus, and the power loss approaches a unique value, respectively, when the B vector evolves into the round locus with the same magnitude from either a series of circles or ellipses

  7. Magnetic properties of heavy-fermion superconductors

    International Nuclear Information System (INIS)

    Rauchschwalbe, U.

    1986-01-01

    In the present thesis the magnetic properties of heavy-fermion superconductors are investigated. The magnetoresistance and the critical magnetic fields show a variety of anomalous phenomena. The Kondo lattices CeCu 2 Si and CeAl 3 are analysed by magnetoresistance and the field dependence of the resistivitis of UBe 13 , UPt 3 , URu 2 Si 2 and CeRu 3 Si are measured for temperatures < or approx. 1 K. (BHO)

  8. Investigation of Synthesis and Magnetic Properties of Rod-Shaped CoFe2O4 via Precipitation-Topotactic Reaction Employing α-FeOOH and γ-FeOOH As Templates

    Science.gov (United States)

    Cao, Xiaohui; Dong, Hongfei; Tan, Yuzhuo; Meng, Jinhong

    2018-03-01

    Rod-shaped CoFe2O4 was prepared by chemical precipitation-topotactic reaction method, and in this preparation needle-like γ-FeOOH and α-FeOOH were synthesized to use as template materials. The evolution of phase and morphology in the process of calcination exhibits that α-FeOOH and γ-FeOOH experienced different routes to form the α-Fe2O3 middle phase with different crystallinity and morphology. The synthesis process of CoFe2O4 revealed that the crystallinity, purity and morphology of CoFe2O4 depend on the α-Fe2O3 middle phase. The magnetic measurement showed that the CoFe2O4 prepared from α-FeOOH has higher saturation magnetization and coercivity, and the crystallinity and morphology may play important roles in achieving a better magnetic performance.

  9. Magnetic properties of confined electron gas

    International Nuclear Information System (INIS)

    Felicio, J.R.D. de.

    1977-04-01

    The effects of confinement by a two or three-dimensional harmonic potential on the magnetic properties of a free electron gas are investigated using the grand-canonical ensemble framework. At high temperatures an extension of Darwin's, Felderhof and Raval's works is made taking into account spin effects at low temperature. A comprehensive description of the magnetic properties of a free electron gas is given. The system is regarded as finite, but the boundary condition psi=0 is not introduced. The limits of weak and strong confinement are also analysed [pt

  10. Annealing effects on magnetic properties of silicone-coated iron-based soft magnetic composites

    International Nuclear Information System (INIS)

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

    2012-01-01

    This paper focuses on novel iron-based soft magnetic composites synthesis utilizing high thermal stability silicone resin to coat iron powder. The effect of an annealing treatment on the magnetic properties of synthesized magnets was investigated. The coated silicone insulating layer was characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. Silicone uniformly coated the powder surface, resulting in a reduction of the imaginary part of the permeability, thereby increasing the electrical resistivity and the operating frequency of the synthesized magnets. The annealing treatment increased the initial permeability, the maximum permeability, and the magnetic induction, and decreased the coercivity. Annealing at 580 °C increased the maximum permeability by 72.5%. The result of annealing at 580 °C shows that the ferromagnetic resonance frequency increased from 2 kHz for conventional epoxy resin coated samples to 80 kHz for the silicone resin insulated composites. - Highlights: ► Silicone uniformly coated the powder, increased the operating frequency of SMCs. ► The annealing treatment increased the DC properties of SMCs. ► Annealing at 580 °C increased the maximum permeability by 72.5%. ► Compared with epoxy coated, the SMCs had higher resistivity annealing at 580 °C.

  11. Ultrasonic-assisted synthesis and magnetic studies of iron oxide/MCM-41 nanocomposite

    International Nuclear Information System (INIS)

    Ursachi, Irina; Vasile, Aurelia; Ianculescu, Adelina; Vasile, Eugeniu; Stancu, Alexandru

    2011-01-01

    Highlights: → A quick and facile route for the synthesis of iron oxide/MCM-41 nanocomposite. → Magnetic nanoparticles were stabilized inside the pores of mesoporous silica MCM-41. → The pore size of MCM-41 dictates the properties of iron oxide nanoparticles. → The procedure provides a narrow size distribution of magnetic nanoparticles. - Abstract: Iron oxide nanoparticles were stabilized within the pores of mesoporous silica MCM-41 amino-functionalized by a sonochemical method. Formation of iron oxide nanoparticles inside the mesoporous channels of amino-functionalized MCM-41 was realized by wet impregnation using iron nitrate, followed by calcinations at 550 deg. C in air. The effect of functionalization level on structural and magnetic properties of obtained nanocomposites was studied. The resulting materials were characterized by powder X-ray diffraction (XRD), high-resolution transmission electron microscopy and selected area electron diffraction (HRTEM and SAED), vibrating sample and superconducting quantum interface magnetometers (VSM and SQUID) and nitrogen adsorption-desorption isotherms measurements. The HRTEM images reveal that the most of the iron oxide nanoparticles were dispersed inside the mesopores of silica matrix and the pore diameter of the amino-functionalized MCM-41 matrix dictates the particle size of iron oxide nanoparticles. The obtained material possesses mesoporous structure and interesting magnetic properties. Saturation magnetization value of magnetic iron oxide nanopatricles stabilized in MCM-41 amino-functionalized by in situ sonochemical synthesis was 1.84 emu g -1 . An important finding is that obtained magnetic nanocomposite materials exhibit enhanced magnetic properties than those of iron oxide/MCM-41 nanocomposite obtained by conventional method. The described method is providing a rather short preparation time and a narrow size distribution of iron oxide nanoparticles.

  12. Magnetic properties of rare-earth intermetallics

    International Nuclear Information System (INIS)

    Kirchmayr, H.

    1978-01-01

    A review is given of the concepts at present used to explain the magnetic properties of rare-earth intermetallics which have been the subject of numerous investigations in recent years. Rare-earth intermetallics with the formula Rsub(a)Bsub(b) are divided according to the magnetic moment of the B atom(s). If there is no magnetic moment present at the B-site, the exchange is only between the magnetic moments at the R-sites, which can only be of indirect character. One possible model is still the RKKY model, although it usually gives in practice only a qualitative description of the magnetic properties. Typical R-B compounds with the B-moment equal to zero are (for instance) the RA1 2 compounds, and related compounds such as the RZn and RCd compounds as well as compounds of the general formula RB 2 (B = Ni, Os, Ir, Pd, Ru or Rh). Of all intermetallics with nonzero B-moment, the R-3d intermetallics are the most important. These intermetallics can be formed with Mn, Fe, Co and Ni. In these systems there exist in principle three interactions, namely between the R-R, R-3d and 3d-3d atoms. The most important is usually the latter interaction. After a short discussion of the crystal structures which occur with R-3d intermetallics, the basic magnetic properties of R-3d intermetallics are presented. These properties are discussed with respect to the formation of a magnetic moment at the 3d site in the framework of present band theories. Special emphasis is given to a discussion of the localized or itinerant character of 3d electrons. (author)

  13. Magnetic properties of iron oxide nanoparticles prepared by seeded-growth route

    International Nuclear Information System (INIS)

    Espinosa, A.; Muñoz-Noval, A.; García-Hernández, M.; Serrano, A.; Jiménez de la Morena, J.; Figuerola, A.; Quarta, A.; Pellegrino, T.; Wilhelm, C.; García, M. A.

    2013-01-01

    In this work we investigate the magnetic properties of iron oxide nanoparticles obtained by two-step synthesis (seeded-growth route) with sizes that range from 6 to 18 nm. The initial seeds result monocrystalline and exhibit ferromagnetic behavior with low saturation field. The subsequent growth of a shell enhances the anisotropy inducing magnetic frustration, and, consequently, reducing its magnetization. This increase in anisotropy occurs suddenly at a certain size (∼10 nm). Electronic and structural analysis with X-ray absorption spectroscopy indicates a step reduction in the oxidation state as the particle reaches 10 nm size while keeping its overall structure in spite of the magnetic polydispersity. The formation of antiphase magnetic boundaries due to island percolation in the growing shells is hypothesized to be the mechanism responsible of the magnetic behavior, as a direct consequence of the two-step synthesis route of the nanoparticles.

  14. Magnetic properties of cyclically deformed austenite

    Energy Technology Data Exchange (ETDEWEB)

    Das, Arpan, E-mail: dasarpan1@yahoo.co.in

    2014-06-01

    In meta-stable austenitic stainless steels, low cycle fatigue deformation is accompanied by a partial stress/strain-induced solid state phase transformation of paramagnetic γ(fcc) austenite phase to ferromagnetic α{sup /}(bcc) martensite. The measured characteristic of magnetic properties, which are the saturation magnetization, susceptibility, coercivity, retentivity, and the area under the magnetic hysteresis loop are sensitive to the total strain amplitude imposed and the corresponding material behaviour. The morphologies and nucleation characteristics of deformation induced martensites (i.e., ϵ(hcp), α{sup /}(bcc)) have been investigated through analytical transmission electron microscope. It has been observed that deformation induced martensites can nucleate at a number of sites (i.e., shear band intersections, isolated shear bands, shear band–grain boundary intersection, grain boundary triple points, etc.) through multiple transformation sequences: γ(fcc)→ϵ(hcp), γ(fcc)→ϵ(hcp)→α{sup /}(bcc), γ(fcc)→ deformation twin →α{sup /}(bcc) and γ(fcc)→α{sup /}(bcc). - Highlights: • LCF tests were done at various strain amplitudes of 304LNSS. • Quantification of martensite was done through ferritecope. • Magnetic properties were characterised through VSM. • Correlation of magnetic properties with the cyclic plastic response was done. • TEM was done to investigate the transformation micro-mechanisms.

  15. Magnetic properties of the ferrimagnetic glass-ceramics for hyperthermia

    International Nuclear Information System (INIS)

    Bretcanu, O.; Verne, E.; Coeisson, M.; Tiberto, P.; Allia, P.

    2006-01-01

    Magnetic materials play a key-role in magnetic induction hyperthermia for the treatment of cancer. In this paper, we analyse the magnetic properties of ferrimagnetic glass-ceramics with the composition in the system SiO 2 -Na 2 O-CaO-P 2 O 5 -FeO-Fe 2 O 3 , as a function of the melting temperature. These materials were obtained by melting of commercial reagents in the temperature range of 1400-1550 o C. Room-temperature magnetic measurements were performed by means of a vibrating sample magnetometer at room temperature. The power loss was determined from calorimetric measurements, using a magnetic induction furnace. The highest power loss (61 W/g) has been obtained for samples melted at 1500 o C. The heat generation of the ferrimagnetic glass-ceramics prepared by two different synthesis methods (traditional melting and coprecipitation-derived) will be compared. These materials are expected to be useful in the localised treatment of cancer

  16. Synthesis of magnetic iron oxide nanoparticles toward arsenic removal from drinking water

    International Nuclear Information System (INIS)

    Starbird Perez, Ricardo; Montero Campos, Virginia

    2015-01-01

    A high contact area material is supplied to be used in the treatment of water contaminated with arsenic. Synthesis of iron nanoparticles is reported with superparamagnetic properties, stabilized with stearic acid. The characterization is performed through spectrophotometric, thermogravimetric and electronic transmission techniques. The presence of an emulsifier is evidenced and determinant for the stabilization of the iron oxide phase (maghemite or magnetite) with magnetic properties. The material is obtained and shows suitable properties to be used in the treatment of water for human consumption. (author) [es

  17. Magnetic Ground State Properties of Transition Metals

    DEFF Research Database (Denmark)

    Andersen, O. K.; Madsen, J.; Poulsen, U. K.

    1977-01-01

    We review a simple one-electron theory of the magnetic and cohesive properties of ferro- and nearly ferromagnetic transition metals at 0 K. The theory is based on the density functional formalism, it makes use of the local spin density and atomic sphere approximations and it may, with further app...

  18. Magnetic properties of four dimensional fermions

    Science.gov (United States)

    Bergman, Oren; Lifschytz, Gilad; Lippert, Matthew

    2013-12-01

    We investigate the Sakai-Sugimoto model at nonzero baryon chemical potential in a background magnetic field in the chiral symmetric phase. We find that a new form of baryonic matter shows up, and we investigate its properties. We find a generated axial current, a reduction in the amount of charge participating in dissipative interactions and a metamagnetic like phase transition at low temperature.

  19. Magnetic properties of TbTiGe

    International Nuclear Information System (INIS)

    Prokes, K.; Tegus, O.; Brueck, E.; Gortenmulder, T.J.; Boer, F.R. de; Buschow, K.H.J.

    2001-01-01

    We have studied the magnetic properties of the compound TbTiGe by means of neutron diffraction in the temperature range 1.7-310 K. We also report on magnetization measurements made at different temperatures and fields. The compound TbTiGe adopts the tetragonal CeFeSi-structure type and orders antiferromagnetically at T N =286 K. The structure is collinear antiferromagnetic in the whole temperature range below T N , with the magnetic moments aligned along the tetragonal c-axis. The uncommon shape of the temperature dependence of the magnetization observed in our sample is attributed to small amounts of the ferromagnetic low-temperature modification of TbTiGe

  20. Maghemite polymer nanocomposites with modulated magnetic properties

    International Nuclear Information System (INIS)

    Millan, A.; Palacio, F.; Falqui, A.; Snoeck, E.; Serin, V.; Bhattacharjee, A.; Ksenofontov, V.; Guetlich, P.; Gilbert, I.

    2007-01-01

    A method is presented for the production of maghemite polymer nanocomposites with modulated magnetic properties. Magnetic nanocomposites prepared using this method show regular variation in the magnetic blocking temperature from 2 K to 300 K, and variation in the saturation magnetization from 0 to 50 emu g -1 (Fe 2 O 3 ). The method is based on the in situ formation of maghemite nanoparticles in nitrogen-base polymer matrixes. The particle size can be varied regularly from 1.5 nm to 16 nm by changing the ratio of iron loading in the polymer and/or the Fe(II)/Fe(III) ratios. The particles are isolated and uniformly distributed within the matrix. The materials were characterized by electron microscopy, electron energy loss spectroscopy, Moessbauer spectroscopy, infrared spectroscopy, small angle X-ray scattering, wide angle X-ray scattering and magnetic measurements. The nanocomposites obtained are useful model material for the study of the magnetic behavior of magnetic nanoparticles, as well as for use in many industrial and biomedical applications

  1. Synthesis of magnetic microtubes decorated with nanowires and cells

    Science.gov (United States)

    Pomar, C. Diaz; Martinho, H.; Ferreira, F. F.; Goia, T. S.; Rodas, A. C. D.; Santos, S. F.; Souza, J. A.

    2018-04-01

    Antiferromagnetic and ferrimagnetic microtubes decorated with nanowires have been obtained during thermal oxidation process, which was assisted by in situ electrical resistivity measurements. The synthesis route including heat treatment and electrical current along with growth mechanism are presented. This simple method and the ability to tune in the magnetic moment of the obtained microtubes going from a nonmagnetic-like to a large magnetization saturation open an avenue for interesting applications. In vitro experiments involving adherence, migration, and proliferation of fibroblasts cell culture on the surface of the microtubes indicated the absence of cytotoxicity for this material. We have also calculated both torque and driving magnetic force for these microtubes with nanowires and cells as a function of external magnetic field gradient which were found to be robust opening the possibility for magnetic bio micro-robot device fabrication and application in biotechnology.

  2. Reduction Expansion Synthesis for Magnetic Alloy Powders

    Science.gov (United States)

    2015-12-01

    in Figure 1, the Army was able to address its need for printable plastic components, thus enabling a reduction in the total quantity of spare...NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release; distribution is unlimited REDUCTION EXPANSION SYNTHESIS FOR...Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202–4302, and to the Office of Management and Budget, Paperwork Reduction Project

  3. Synthesis of magnetic CoPt/SiO{sub 2} core-shell nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Seto, Takafumi [Research Consortium for Synthetic Nano-Function Materials Project (SYNAF), National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Koga, Kenji [Research Consortium for Synthetic Nano-Function Materials Project (SYNAF), National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Takano, Fumiyoshi [Research Consortium for Synthetic Nano-Function Materials Project (SYNAF), National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Akinaga, Hiroyuki [Research Consortium for Synthetic Nano-Function Materials Project (SYNAF), National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Orii, Takaaki [Research Consortium for Synthetic Nano-Function Materials Project (SYNAF), National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Hirasawa, Makoto [Research Consortium for Synthetic Nano-Function Materials Project (SYNAF), National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Murayama, Mitsuhiro [National Institute for Material Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan)

    2007-04-15

    Core-shell nanoparticles composed of ferromagnetic cobalt platinum cores covered by non-magnetic silica shells were synthesized by laser ablating a composite target in a helium background gas. The average diameter of the CoPt core was controlled by adjusting the CoPt/SiO{sub 2} ratio of the ablation target. The particles were also classified in the gas phase using an electrical mobility classifier. The present method successfully synthesized nearly monodispersed nanoparticles with an average core diameter of 2.5nm. This article describes the synthesis of the core-shell nanoparticles and investigates their magnetic properties.

  4. Synthesis of Beam Lines with Necessary Properties

    CERN Document Server

    Andrianov, Serge

    2005-01-01

    In this paper a new approach to the problem of synthesis of beam lines is discussed. Usually this problem can be overcome by the use of numerical simulation and optimal control theory methods. But this results in sufficiently great number of variable parameters and functions. Obviously, that this degrades quality of a modeling procedure. The suggested approach is demonstrated on a problem of a microprobe design problem. Essence of the problem is that necessary to design a high precision focusing system which satisfies some additional conditions. For solution of this problem we use an algebraic treatment based on Lie algebraic methods and computer algebra techniques. Using the symmetry ideology this approach allows rewriting beam properties to enough simple conditions for control parameters and functions. This leads a set of desired solutions and show results in some most suitable form. Moreover, this approach decreases the number of variable parameters.

  5. Spectroscopic properties of transition elements and their related magnetic properties

    International Nuclear Information System (INIS)

    Porcher, P.; Malta, O.L.

    1988-01-01

    The optical and magnetic properties of transition elements (nd N and nf N ions) are analysed. The phenomenological parameters introduced in the crystal-ligand field theory, the free ion interactions and crystalline matrix as well as electrostatic repulsion are studied. (M.J.C.) [pt

  6. Soft magnetic moldable composites: Properties and applications

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Leif, E-mail: leif.svensson@iprod.lth.se [Lund University, Division of Production and Materials Engineering, Box 188, 221 00 Lund (Sweden); Frogner, Kenneth, E-mail: kenneth.frogner@iprod.lth.se [Lund University, Division of Production and Materials Engineering, Box 188, 221 00 Lund (Sweden); Jeppsson, Peter, E-mail: peter.jeppsson@iprod.lth.se [Lund University, Division of Production and Materials Engineering, Box 188, 221 00 Lund (Sweden); Cedell, Tord, E-mail: tord.cedell@iprod.lth.se [Lund University, Division of Production and Materials Engineering, Box 188, 221 00 Lund (Sweden); Andersson, Mats, E-mail: mats.andersson@iprod.lth.se [Lund University, Division of Production and Materials Engineering, Box 188, 221 00 Lund (Sweden)

    2012-09-15

    A new type of electromagnetic soft magnetic material (SMM) is introduced, based on spherical iron powder particles and a suitable polymer binder. A key feature of this material is that it can be cast or molded into almost any 3D shape, hence the denotation soft magnetic moldable composite (SM{sup 2}C). The SM{sup 2}C is compared with a set of reference materials, such as ferrites, laminated steels, and soft magnetic composites, in terms of primary properties such as permeability and loss, and other properties, such as thermal conductivity and manufacturability. The SM{sup 2}C has the obvious disadvantage of relatively low permeability, but offers benefits such as relatively low losses and high potential for close integration into electromagnetic circuits. Some recent SM{sup 2}C applications are illustrated, and design and manufacturing aspects are discussed. - Highlights: Black-Right-Pointing-Pointer A new type of soft magnetic composite is introduced. Black-Right-Pointing-Pointer Properties are compared to other flux core materials. Black-Right-Pointing-Pointer The new material has low losses but also low permeability. Black-Right-Pointing-Pointer Potential benefits in freedom of design and manufacturing issues.

  7. Process optimization and properties of magnetically hard cobalt carbide nanoparticles via modified polyol method

    International Nuclear Information System (INIS)

    Zamanpour, Mehdi; Bennett, Steven P.; Majidi, Leily; Chen, Yajie; Harris, Vincent G.

    2015-01-01

    Highlights: • High-coercivity cobalt carbides were synthesized by polyol method. • No rare earth elements were used during synthesis process. • Process parameters (reaction temperature, precursors’ concentrations, surfactants and reaction duration) were studied/optimized. • Process was scaled-up to synthesis more than 5 g powders per batch. - Abstract: Cobalt carbide magnetic nanoparticles were successfully synthesized via a modified polyol process without using a rare-earth catalyst during the synthesis process. The present results show admixtures of Co 2 C and Co 3 C phases possessing magnetization values exceeding 47 emu/g and coercivity values exceeding 2.3 kOe at room temperature. Moreover, these experiments have illuminated the important role of the reaction temperature, hydroxyl ion concentrations and the reaction duration on the crystallographic structure and magnetic properties of the nanoparticles. The crystallographic structure and particle size of the Co x C nanoparticles were characterized by X-ray diffractometry and scanning electron microscopy. Vibrating sample magnetometry was used to determine magnetic properties. Scale-up of synthesis to more than 5 g per batch was demonstrated with no significant degradation of magnetic properties

  8. Process optimization and properties of magnetically hard cobalt carbide nanoparticles via modified polyol method

    Energy Technology Data Exchange (ETDEWEB)

    Zamanpour, Mehdi; Bennett, Steven P. [Center for Microwave Magnetic Materials and Integrated Circuits (CM3IC), Northeastern University, Boston, MA 02115 (United States); Majidi, Leily [Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA 02115 (United States); Chen, Yajie [Center for Microwave Magnetic Materials and Integrated Circuits (CM3IC), Northeastern University, Boston, MA 02115 (United States); Harris, Vincent G. [Center for Microwave Magnetic Materials and Integrated Circuits (CM3IC), Northeastern University, Boston, MA 02115 (United States); Department of Electrical and Computer Engineering, Northeastern University, Boston, MA 02115 (United States)

    2015-03-15

    Highlights: • High-coercivity cobalt carbides were synthesized by polyol method. • No rare earth elements were used during synthesis process. • Process parameters (reaction temperature, precursors’ concentrations, surfactants and reaction duration) were studied/optimized. • Process was scaled-up to synthesis more than 5 g powders per batch. - Abstract: Cobalt carbide magnetic nanoparticles were successfully synthesized via a modified polyol process without using a rare-earth catalyst during the synthesis process. The present results show admixtures of Co{sub 2}C and Co{sub 3}C phases possessing magnetization values exceeding 47 emu/g and coercivity values exceeding 2.3 kOe at room temperature. Moreover, these experiments have illuminated the important role of the reaction temperature, hydroxyl ion concentrations and the reaction duration on the crystallographic structure and magnetic properties of the nanoparticles. The crystallographic structure and particle size of the Co{sub x}C nanoparticles were characterized by X-ray diffractometry and scanning electron microscopy. Vibrating sample magnetometry was used to determine magnetic properties. Scale-up of synthesis to more than 5 g per batch was demonstrated with no significant degradation of magnetic properties.

  9. Structure and Magnetic Properties of Lanthanide Nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Dickerson, James Henry [Vanderbilt Univ., Nashville, TN (United States)

    2014-06-01

    We have had considerable success on this project, particularly in the understanding of the relationship between nanostructure and magnetic properties in lanthanide nanocrystals. We also have successfully facilitated the doctoral degrees of Dr. Suseela Somarajan, in the Department of Physics and Astronomy, and Dr. Melissa Harrison, in the Materials Science Program. The following passages summarize the various accomplishments that were featured in 9 publications that were generated based on support from this grant. We thank the Department of Energy for their generous support of our research efforts in this area of materials science, magnetism, and electron microscopy.

  10. Synthesis, characterization and study of the magnetic properties of a coordination polymer containing cobalt(II) and copper(II); Sintese, caracterizacao e estudo das propriedades magneticas de um polimero de coordenacao contendo cobalto(II) e cobre(II)

    Energy Technology Data Exchange (ETDEWEB)

    Cunha, Tamyris T. da; Stumpf, Humberto O.; Pereira, Cynthia L.M., E-mail: cynthialopes@ufmg.br [Departamento de Quimica, Instituto de Ciencias Exatas, Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil); Pires, Heber S.; Oliveira, Luiz F.C. de [Departamento de Quimica, Instituto de Ciencias Exatas, Universidade Federal de Juiz de Fora, MG (Brazil); Pedroso, Emerson F. [Departamento de Quimica, Centro Federal de Educacao Tecnologica de Minas Gerais, Belo Horizonte, MG (Brazil); Nunes, Wallace C. [Instituto de Fisica, Universidade Federal Fluminense, Niteroi, RJ (Brazil)

    2012-07-01

    This work describes the synthesis and characterization of two new compounds with ligand opy (N-(2-pyridyl)oxamate): the copper(II) precursor [Me{sub 4}N]{sub 2}[Cu(opy){sub 2}].5H{sub 2}O and Co{sup II} Cu{sup II} coordination polymer {l_brace}[Co Cu(opy){sub 2}]{r_brace}{sub n}x4nH{sub 2}O. This latter compound was obtained by reaction of [Me{sub 4}N]{sub 2}[Cu(opy){sub 2}].5H{sub 2}O and CoCl{sub 2}.6H{sub 2}O in water. The heterobimetallic Co{sup II} Cu{sup II} chain was characterized by elemental analysis, IR spectroscopy, thermogravimetry and magnetic measurements. Magnetic characterization revealed typical behavior of one-dimensional (1D) ferrimagnetic chain as shown in the curves of temperature (T) dependence of magnetic susceptibility ({chi}{sub M}), in the form of {chi}{sub M}T versus T, and dependence of magnetization (M) with applied field (H). (author)

  11. Magnetic properties of magnetic glass-like carbon prepared from furan resin alloyed with magnetic fluid

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Kazumasa, E-mail: naka@sss.fukushima-u.ac.jp [Materials Science Area, Graduate School of Symbiotic Systems Science and Technology, Fukushima University, 1 Kanayagawa, Fukushima 960-1296 (Japan); Okuyama, Kyoko [Materials Science Area, Graduate School of Symbiotic Systems Science and Technology, Fukushima University, 1 Kanayagawa, Fukushima 960-1296 (Japan); Takase, Tsugiko [Institute of Environmental Radioactivity (IER), Fukushima University, 1 Kanayagawa, Fukushima 960-1296 (Japan)

    2017-03-01

    Magnetic glass-like carbons that were heat-treated at different temperatures or were filled with different magnetic nanoparticle contents were prepared from furan resin alloyed with magnetic fluid (MF) or Fe{sub 3}O{sub 4} powder in their liquid-phase states during mixing. Compared to the Fe{sub 3}O{sub 4} powder-alloyed carbon, the MF-alloyed carbon has highly dispersed the nanoparticles, and has the excellent saturation magnetization and coercivity. It is implied that saturation magnetizations are related to changes in the types of phases for the nanoparticles and the relative intensities of X-ray diffraction peaks for iron and iron-containing compounds in the carbons. Additionally, the coercivities are possibly affected by the size and crystallinity of the nanoparticles, the relative amounts of iron, and the existence of amorphous compounds on the carbon surfaces. - Highlights: • Magnetic glass-like carbons were prepared from furan resin alloyed with magnetic fluid. • The nanoparticles of MF-alloyed GLCs were highly dispersed. • MF-alloyed GLCs had excellent magnetic properties compared to powder-alloyed ones. • The magnetic properties changed with treatment temperature and nanoparticle content. • The changes in magnetic properties were investigated with XRD and FE-SEM.

  12. Magnet properties of Mn70Ga30 prepared by cold rolling and magnetic field annealing

    International Nuclear Information System (INIS)

    Ener, Semih; Skokov, Konstantin P.; Karpenkov, Dmitriy Yu.; Kuz'min, Michael D.; Gutfleisch, Oliver

    2015-01-01

    The remanence and coercivity of arc melted Mn 70 Ga 30 can be substantially improved by cold rolling. For best performance the rolled material should be annealed at T=730 K in the presence of a magnetic field of 1 T. The so-obtained magnet has a remanence of 0.239 T and a coercivity of 1.24 T at room temperature. The underlying reason for the high coercivity and remanence is the increase of the content of a metastable ferrimagnetic D0 22 phase at the expense of the normally stable anti-ferromagnetic D0 19 . Magnetic field significantly increases the nucleation rate of the ferromagnetic D0 22 phase that leads to grain size refinement and as a consequence of improving remanence and coercive field. - Highlights: • Alternative synthesis method for D0 22 phase formation in Mn–Ga is developed. • Effect of cold rolling and annealing on magnetic properties of Mn 70 Ga 30 is examined. • Small magnetic fields are sufficient to accelerate nucleation of the D0 22 phase

  13. 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 ...

  14. Facile directing agent-free synthesis and magnetism of nanocrystalline Fe–Ni alloy with tunable shape

    International Nuclear Information System (INIS)

    Mohamed, Marwa A.A.

    2014-01-01

    Highlights: • Simple directing agent-free wet chemical method for high-yield synthesis of nc Fe-Ni particles with tunable shape. • The alloy morphology is controlled by varying synthesis conditions; concentration of metal ions and pH of reaction. • Synthesis conditions control the final shape of alloy particles via controlling their growth rate and capping with OH − ions. • The alloy magnetic behavior is driven away from soft magnetic toward hard one, by particles anisotropy and size reduction. • The branched wires morphology can be considered a new morphology of distinctive magnetic behavior, for nc Fe-Ni alloy. - Abstract: This article reports the synthesis of nanocrystalline (nc) Fe 20 Ni 80 particles with tunable shape, using a heterogeneous directing agent-free aqueous wet chemical method of mild synthesis conditions. The particle morphology has been controlled by varying synthesis conditions. The results demonstrate that the morphology of alloy particles changes from quasi-isotropic to anisotropic architecture by decreasing concentration of metal ions or increasing pH of reaction solution. Deep interpretations of such phenomena are reported. Magnetic behavior of the alloy is driven away from soft magnetic and toward hard magnetic behavior, by anisotropy and size reduction of alloy particles. This broadens practical applications of nc Fe 20 Ni 80 alloy. Overall, the study provides an effective economical way for high-yield synthesis of nc Fe–Ni particles with tailored shape and subsequently magnetic properties for a specific technological application. Additionally, it adds a new morphology, highly branched wires, of distinctive magnetic behavior to the known morphologies of nc Fe–Ni particles

  15. Study of the polymer permanent magnets properties - rare earths

    International Nuclear Information System (INIS)

    Takiishi, H.; Benini, H.R.; Lima, L.F.C.P.; Faria, R.N.

    1996-01-01

    An alternative method for permanent magnet production without the sintering step is polymer bonded magnets. In this work magnets were prepared from magnetic Sm Co 5 or Nd 15 Fe 77 B 8 alloys bonded with 10% wt of resin. For the Nd 15 Fe 77 B 8 alloy the hydrogenation - decomposition - desorption - recombination (HDDR) process have been employed in the preparation of the magnets. Results from the magnetic properties showed that no milling is necessary for the production of polymer bonded Nd-Fe-B magnets. The magnets showed good magnetic properties. (author)

  16. Preparation and properties of the magnetic absorbent polymer via the chemical transformation process

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shengyu, E-mail: liusytyut@sina.com [Department of Mineral Processing, College of Mining Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Key Laboratory of In-situ Property-improving Mining of Ministry of Education, Taiyuan University of Technology, Taiyuan 030024 (China); Zhang, Suhong, E-mail: zhangsh04@sina.com [Department of Mineral Processing, College of Mining Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Guo, Jianying; Wen, Jing; Qiao, Yan [Department of Mineral Processing, College of Mining Engineering, Taiyuan University of Technology, Taiyuan 030024 (China)

    2017-01-15

    Magnetic polyacrylic acid sodium polymer (MPAAS) was prepared by chemical transformation method. Key parameters were investigated in the synthesis process of the magnetic polymer and an optimum preparation condition was gained. The structure of the magnetic polymer was characterized by X-ray diffraction (XRD), Fourier transform infrared spectrosocopy (FTIR) and scanning electron microscope (SEM). Magnetic property of the magnetic polymer was measured by the magnet and superconducting quantum interference device (SQUID). Both the swelling ratio and kinetics and the water retention ratio and kinetics were investigated. Based on the results, it can be gained that both swelling rate and equilibrium swelling rate were lowered after magnetization while the water retention ability of the magnetic polymer is stronger than that of the polymer. - Highlights: • The preparation mechanism of the magnetic polymer was proposed. • The magnetic property of the magnetic polymer was related to reaction conditions. • Swelling ratio and kinetics of polymer and magnetic polymer were studied. • Water retention ratio and kinetics of polymer and magnetic polymer were studied.

  17. Preparation and properties of the magnetic absorbent polymer via the chemical transformation process

    International Nuclear Information System (INIS)

    Liu, Shengyu; Zhang, Suhong; Guo, Jianying; Wen, Jing; Qiao, Yan

    2017-01-01

    Magnetic polyacrylic acid sodium polymer (MPAAS) was prepared by chemical transformation method. Key parameters were investigated in the synthesis process of the magnetic polymer and an optimum preparation condition was gained. The structure of the magnetic polymer was characterized by X-ray diffraction (XRD), Fourier transform infrared spectrosocopy (FTIR) and scanning electron microscope (SEM). Magnetic property of the magnetic polymer was measured by the magnet and superconducting quantum interference device (SQUID). Both the swelling ratio and kinetics and the water retention ratio and kinetics were investigated. Based on the results, it can be gained that both swelling rate and equilibrium swelling rate were lowered after magnetization while the water retention ability of the magnetic polymer is stronger than that of the polymer. - Highlights: • The preparation mechanism of the magnetic polymer was proposed. • The magnetic property of the magnetic polymer was related to reaction conditions. • Swelling ratio and kinetics of polymer and magnetic polymer were studied. • Water retention ratio and kinetics of polymer and magnetic polymer were studied.

  18. The role of the nature of pillars in the structural and magnetic properties of magnetic pillared vlays

    DEFF Research Database (Denmark)

    Bachir, Cherifa; Lan, Yanhua; Mereacre, Valeriu

    2011-01-01

    of pillared clays by examining in detail the influence of the calcination temperature and the nature of different pillared clays on these properties. Magnetic layered systems from different pillared clays were prepared and characterized. Firstly, Ti-, Al-, and Zr-pillared clays (Ti-PILCs, Al-PILCs, and Zr......-PILCs, respectively) were produced at different calcination temperatures and then magnetic pillared clays (Ti-M-PILCs, Al-M-PILCs, and Zr-M-PILCs) were prepared at ambient temperature. The synthesis involves a reduction in aqueous solution of the original Fe-exchanged pillared clay using NaBH4. The structural....... Similar experiments with Al- and Zr-pillars have been discussed. A correlation between the XRF data, porosity, FF calculation, and magnetic properties led to the conclusion that the sample Al-M-PILC previously calcined at 500 degrees C was the most stable material after the magnetization process. The same...

  19. The critical properties of magnetic films

    International Nuclear Information System (INIS)

    Saber, M.; Ainane, A.; Essaoudi, I.; Miguel, J.J. de

    2010-01-01

    Within the framework of the transverse spin-1/2 Ising model and by using the effective field theory with a probability distribution technique that accounts for the self spin correlations, we have studied the critical properties of an L-layer film of simple cubic symmetry in which the exchanges strength are assumed to be different from the bulk values in N S surface layers. We derive and illustrate the expressions for the phase diagrams, order parameter profiles and susceptibility. In such films, the critical temperature can shift to either lower or higher temperature compared with the corresponding bulk value. We calculate also some magnetic properties of the film, such as the layer magnetizations, their averages and their profiles and the longitudinal susceptibility of the film. The film longitudinal susceptibility still diverges at the film critical temperature as does the bulk longitudinal susceptibility.

  20. Design and synthesis of plasmonic magnetic nanoparticles

    International Nuclear Information System (INIS)

    Lim, Jit Kang; Tilton, Robert D.; Eggeman, Alexander; Majetich, Sara A.

    2007-01-01

    Core-shell nanoparticles containing both iron oxide and gold are proposed for bioseparation applications. The surface plasmon resonance of gold makes it possible to track the positions of individual particles, even when they are smaller than the optical diffraction limit. The synthesis of water-dispersible iron oxide-gold nanoparticles is described. Absorption spectra show the plasmon peaks for Au shells on silica particles, suggesting that thin shells may be sufficient to impart a strong surface plasmon resonance to iron oxide-gold nanoparticles. Dark field optical microscopy illustrates the feasibility of single-particle detection. Calculations of magnetophoretic and drag forces for particles of different sizes reveal design requirements for effective separation of these small particles

  1. Magnesium substitutions in rare-earth metal germanides with the Gd5Si4 type. Synthesis, structure determination and magnetic properties of RE5-xMgxGe4 (RE=Gd-Tm, Lu and Y)

    Energy Technology Data Exchange (ETDEWEB)

    Sarrao, J L [Los Alamos National Laboratory; Thompson, Joe D [Los Alamos National Laboratory; Tobash, P H [UNIV. OF DE; Bobev, S [UNIV. OF DE

    2009-01-01

    A series of magnesium-substituted rare-earth metal germanides with a general formula RE{sub 5-x}Mg{sub x}Ge{sub 4} (x {approx} 1.0-2.3; RE =Gd-Tm, Lu, Y) have been synthesized by high-temperature reactions and structurally characterized by single-crystal X-ray diffraction. These compounds crystallize with the common Gd{sub 5}Si{sub 4} type in the orthorhombic space group Pnma (No. 62; Z =4; Pearson's code oP36) and do not appear to undergo temperature-induced crystallographic phase transitions down to 120 K. Replacing rare-earth metal atoms with Mg, up to nearly 45 % at., reduces the valence electron count and is clearly expressed in the subtle changes of the Ge-Ge and metal-metal bonding. Magnetization measurements as a function of the temperature and the applied field reveal complex magnetic structures at cryogenic temperatures, and Curie-Weiss paramagnetic behavior at higher temperatures. The observed local moment magnetism is consistent with RE+ ground states in all cases. In the magnetically ordered phases, the magnetization cannot reach saturation in fields up to 50 kOe. The structural trends across the series and the variations of hte magnetic properties as a function of the Mg content are also discussed. KEYWORDS: Rare-earth intermetallics, germanides, crystal structure,Gd{sub 5}Si{sub 4} type.

  2. Electro-magnetic properties of heavy nuclei

    International Nuclear Information System (INIS)

    Otsuka, Takaharu

    1989-01-01

    Two topics of electro-magnetic properties of heavy nuclei are discussed. The first topic is the M1 excitation from well-deformed heavy nuclei, and the other is the sudden increase of the isotope shift as a function of N in going away from the closed shell. These problems are considered in terms of the particle-number projected (Nilsson-) BCS calculation. (author)

  3. Graphene Nanoelectronics Metrology, Synthesis, Properties and Applications

    CERN Document Server

    2012-01-01

    Graphene is a perfectly two-dimensional single-atom thin membrane with zero bandgap. It has attracted huge attention due to its linear dispersion around the Dirac point, excellent transport properties, novel magnetic characteristics, and low spin-orbit coupling. Graphene and its nanostructures may have potential applications in spintronics, photonics, plasmonics and electronics. This book brings together a team of experts to provide an overview of the most advanced topics in theory, experiments, spectroscopy and applications of graphene and its nanostructures. It covers the state-of-the-art in tutorial-like and review-like manner to make the book useful not only to experts, but also newcomers and graduate students.

  4. Hyperfine Interactions and Some Magnetic Properties of Nanocrystalline Co40Fe50Ni10 and Co50Fe45Ni5 Alloys Prepared by Mechanical Synthesis and Subsequently Heat Treated

    International Nuclear Information System (INIS)

    Pikula, T.; Oleszak, D.; Pekala, M.

    2011-01-01

    Co 40 Fe 50 Ni 10 and Co 50 Fe 45 Ni 5 ternary alloys were prepared by mechanical alloying method. To check the stability of their structure thermal treatment was applied subsequently. As X-ray diffraction studies proved the final products of milling were the solid solutions with bcc lattice and the average grain sizes ranged of tens of nanometers. After heating of the Co 50 Fe 45 Ni 5 alloy up to 993 K the mixture of two solid solutions with bcc and fcc lattices was formed. In other cases thermal treatment did not change the type of the crystalline lattice. Moessbauer spectroscopy revealed hyperfine magnetic field distributions which reflected the different possible atomic surroundings of 57 Fe isotopes. Results of the macroscopic magnetic measurements proved that both investigated alloys had relatively good soft magnetic properties. (authors)

  5. Chemical synthesis of magnetic Fe-B and Fe-Co-B particles and chains

    International Nuclear Information System (INIS)

    Fulmer, P.; Kim, J.; Manthiram, A.; Sanchez, J.M.

    1999-04-01

    With an objective to develop magnetic materials with high saturation magnetization for the Magnetically Assisted Chemical Separation (MACS) process the chemical synthesis of Fe-B and Fe-Co-B alloys by reducing iron and cobalt chloride solutions with potassium borohydride has been investigated systematically. The influence of the concentration of the reactants, applied magnetic field, reaction atmosphere, and method of mixing the reactants on the microstructure, particle size, composition and magnetic properties has been studied. Both M-B (M = Fe and Co) particles and elongated chains composed of nanometer size M-B particles have been obtained depending on the reaction conditions. The Fe-B samples exhibit saturation magnetization of M S of 120--190 emu/g, remanent magnetization M r of 10--22 emu/g, and coercive field H c of 400--900 Oe. A high M S value of 190 emu/g, which is close to the theoretical value of 218 emu/g for pure Fe, has been achieved particularly for samples with well-defined chain structures. Increasing the Co content in the Fe-Co-B alloys increases the boron content and thereby decreases the crystallinity and M S values although marginal increase in H c (1,250 Oe) and M r (36 emu/g) values could be made in some Fe-Co-B compositions. The chain structure with high M S may be attractive for other magnetic separation processes as well

  6. Microstructure, magnetic properties and magnetic hardening in 2:17 Sm-Co magnets

    International Nuclear Information System (INIS)

    Tang, W.; Zhang, Y.; Hadjipanayis, G.C.

    2002-01-01

    A comprehensive and systematic study has been made on Sm(Co,Fe,M,L) z magnets (M=Cu or Ni, and L=Zr or Ti) to completely understand the effects of composition and processing on the microstructure and magnetic properties of magnets. Ti-containing magnets do not have a lamellar phase but exhibit only a cellular microstructure, resulting in a much lower coercivity (below 10 kOe). Ni-containing magnets exhibit a perfect cellular/lamellar microstructure, but without a large domain wall energy gradient at the interface of the 2:17 and 1:5 phases, leading to a low coercivity. Only in the magnets containing both Cu and Zr, a uniform and stable cellular/lamellar microstructure with a high domain wall energy gradient across the 1:5 phase is formed, resulting in high coercivity. These results indicate that the conditions for effective magnetic hardening are: (1) Formation of a cellular/lamellar microstructure, and (2) establishment of a domain wall energy gradient at the cell boundaries. Based on all of these experimental results, the magnetization reversal mechanism of 2:17 Sm-Co magnets can be explained by both the domain wall pinning and nucleation models. The nucleation mechanism holds at any temperature in the Cu-rich magnets, and only above the Curie temperature of the 1:5 phase in the alloys with the lower Cu content. In these cases, the 2:17 cells become magnetically decoupled. (orig.)

  7. Mechanochemical synthesis of nanocrystalline Fe and Fe–B magnetic alloys

    International Nuclear Information System (INIS)

    Mohammadi, Majid; Ghasemi, Ali; Tavoosi, Majid

    2016-01-01

    Mechanochemical synthesis and magnetic characterization of nanocrystalline Fe and Fe–B magnetic alloys was the goal of this study. In this regard, different Fe_2O_3–B_2O_3 powder mixtures with sufficient amount of CaH_2 were milled in a planetary ball mill in order to produce nanocrystalline Fe, Fe_9_5B_5 and Fe_8_5B_1_5 alloys. The produced samples were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The results showed that, nanocrystalline Fe, Fe_9_5B_5 and Fe_8_5B_1_5 alloys can be successfully synthesized by the reduction reaction of Fe_2O_3 and B_2O_3 with CaH_2 during mechanical alloying. The structure of produced Fe_9_5B_5 and Fe_8_5B_1_5 alloys was a combination of Fe and Fe_2B phases with average crystallite sizes of about 15 and 10 nm, respectively. The produced nanocrystalline alloys exhibited soft magnetic properties with the coercivity and saturation of magnetization in the range of 170–240 Oe and 9–28 emu/g, respectively. Increasing the boron content has a destructive effect on soft magnetic properties of Fe–B alloys. - Highlights: • We study the mechanochemical synthesis of nanocrystalline boron, Fe and Fe–B alloys. • We study the reduction reaction of B_2O_3–CaH_2 during milling. • We study the reduction reaction of Fe_2O_3–CaH_2 during milling. • We study the reduction reaction of Fe_2O_3–B_2O_3–CaH_2 during milling. • We study the effect of B on magnetic properties of nanocrystalline Fe–B alloys.

  8. The magnetic properties of mill scale-derived permanent magnet

    International Nuclear Information System (INIS)

    Woon, H.S.; Hashim, M.M.; Yahya, N.; Zakaria, A.; Lim, K.P.

    2005-01-01

    In the permanent magnet SrO-FeO-Fe 2 O 3 system, there exist several magnetically ordered compounds with a stable phase at room temperature. The most important are the M(SrFe 12 O 19 ), X(SrFe 15 O 23 ) and W(SrFe 18 O 27 ) phases with hexagonal close packed structure. In this project, M(SrFe 12 O 19 ) was prepared using mill scale, a steel-maker byproduct, as raw material. The Malaysia steel industry generates approximately 30,000 metric tons of waste products such as mill scale every year. Transportation and disposal of the byproducts are costly and the environmental regulations are becoming stricter. Hence, local steel mills are to find new ways to recycle the waste as a feedstock for the steel-making process or as a saleable product. The M(SrFe 12 O 19 ) was synthesized using the conventional ceramic process. The formation of the SrFe 12 O 19 was confirmed by X-ray diffraction. The magnetic properties such as the energy product (BH)max, coercive force (iHc) and remanence (Br) were also reported in this paper. (Author)

  9. Synthesis and superconducting properties of niobium germanium

    International Nuclear Information System (INIS)

    Kihlstrom, K.E.

    1982-01-01

    By carefully controlling temperature homogeneity during preparation of the Nb 3 Ge samples, homogeneous films have been prepared of high-T/sub c/Nb 3 Ge. Homogeneity is demonstrated by a sharp transition width (ΔT/sub c/ 6 amps/cm 2 which are the highest ever reported for any material at this temperature. The successful film synthesis has made it possible to study the superconducting properties of Nb 3 Ge. High quality A15 NbGe/(SiO/sub x/)/Pb tunnel juctions on electron beam codeposited oxygen-doped Nb 3 Ge have been fabricated. 2Δ/(k/sub B/T/sub c/ rises from the BCS limit in Ge-poor samples to become strong coupled (2Δk/sub B/T/sub c/ approx. 4.35) as stoichiometry is approached. The electron-phonon spectral function α 2 F(ω) and related microscopic parameters were obtained. As the T/sub c/ and gap increase, a movement of the lowest phonon branch to lower energies is observed with a resultant decrease in (ω 2 ). Thus lambda increases with T/sub c/ while (ω 2 ) decreases in agreement with the idea that mode softening is a major factor in the increase of T/sub c/ with approach to stoichiometry as previously found in Nb 3 Al by Kwo and Geballe

  10. Synthesis and properties of superheavy elements

    CERN Document Server

    Hofmann, S

    2003-01-01

    The nuclear shell model predicts that the next doubly magic shell-closure beyond sup 2 sup 0 sup 8 Pb is at a proton number Z = 114, 120, or 126 and at a neutron number N = 172 or 184. The outstanding of experimental investigations is the exploration of this region of spherical 'SuperHeavy Elements' (SHEs). Experimental methods are described which allowed for the identification of elements 107 to 112 in studies of cold fusion reactions based on lead and bismuth targets. Also presented are data which were obtained on the synthesis of elements 112, 114, and 116 in investigation of hot fusion reactions using actinide targets. The decay data reveal that for the heaviest elements, the dominant decay mode is alpha emission, not fission. Decay properties as well as reaction cross- sections are compared with the results of theoretical studies. Finally, plans are presented for the further development of the experimental set-up and the application of new techniques. At a higher sensitivity, the exploration of the regio...

  11. Novel metallomesogenic polyurethanes: Synthesis, characterization and properties

    International Nuclear Information System (INIS)

    Senthilkumar, Natarajan; Narasimhaswamy, Tanneru; Kim, Il-Jin

    2012-01-01

    A series of tetradentate Schiff base metallomesogenic diols were synthesized from two simple dihydroxy benzenes. The metallomesogenic diol was constructed from three ring containing mesogen linked through ester and azomethine with terminal hydroxy group. This upon complexation with copper(II) formed metallomesogenic diol with varying terminal chain length. A series of metallomesogenic polyurethanes were synthesized using these metallomesogenic diols as chain extenders for the prepolymers based on polytetramethylene glycol (PTMG) of varying molecular weight (M n = 650, 2000) and 2,4-toluene diisocyanate (TDI), or 4,4′-methylene bis(phenyl isocyanate) (MDI). The molar ratio of metallomesogenic diol and PTMG were varied in the polyurethane to find their role in liquid crystalline and mechanical properties. Extensive characterization of all metallomesogenic compounds and intermediates were carried out by FT-IR, 1 H and 13 C NMR, EPR, VSM, Mass (EI and FAB) and UV–visible spectroscopy. Hot stage polarizing microscope and differential scanning calorimetry were used to ensure the phase characteristics such as nature of phase, melting and clearing temperatures and phase range. The appearance of enantiotropic smectic A phases indicated high molecular polarizability of the core due to the metal ion. - Highlights: ► Design and synthesis of metallomesogenic diols. ► Metallomesogenic polyurethanes were prepared using these diols as chain extenders. ► Liquid crystalline and mechanical properties were studied. ► A square pyramidal structure for the copper(II) complexes have been proposed. ► Polyurethanes exhibited enantiotropic smectic A phases.

  12. Mechanical properties, microstructure and magnetic properties of composite magnet base on SrO.6Fe_2O_3 (SRM)-thermoplastic and thermoset polymer

    International Nuclear Information System (INIS)

    Grace Tj Sulungbudi; Aloma Karo Karo; Mujamilah; Sudirman

    2010-01-01

    The use of magnets in industrial applications do not always require high magnetic properties. Therefore, the use of polymer as a matrix that serves as a binder can be applied to obtain lightweight, flexible and cheap composite magnet. This report discuss composite magnet base on SrO.6Fe_2O_3(SRM)-thermoplastic and thermoset polymer. Thermoplastic polymer consist of polypropylene (PP) type of PP2 and PP10 and polyethylene (PE) type of LDPE were used. For thermoset polymer, epoxy and polyester were used. Synthesis of composite magnet based on thermoplastic polymer (PP2, PP10, LDPE) were carried using the blending method, while the thermoset composites magnet using casting method. Thermoplastic composite magnets were prepared with compositions of 50, 41, 38, 33 and 29 % weight of SRM with the blending temperature of 160 °C for LDPE and 180 °C for PP2 and PP10. For thermoset composite magnets, the compositions were 30, 40, 50 and 60 % by weight of SRM. The mechanical test conducted include tensile strength and elongation at break. Microstructure on the surface of the composite materials were observed using SEM (Scanning Electron Microscope) and the magnetic properties were measured using VSM (Vibrating Sample Magnetometer). The SEM results showed the formation of flat shape powder particle with size of 1.6 µm. In general, the mechanical properties of polypropylene polymer composite magnet are better than that using polyethylene (LDPE) binder. For polypropylene binder PP10 is better than PP2. Magnetic properties are not significantly affected by the change of polymer or binder types. (author)

  13. Magnetic microstructure and magnetic properties of spark plasma sintered NdFeB magnets

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Y.L., E-mail: hyl1019_lin@163.com [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Wang, Y.; Hou, Y.H.; Wang, Y.L.; Wu, Y.; Ma, S.C. [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Liu, Z.W.; Zeng, D.C. [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Tian, Y.; Xia, W.X. [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Zhong, Z.C., E-mail: zzhong2014@sina.com [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China)

    2016-02-01

    Nanocrystalline NdFeB magnets were prepared by spark plasma sintering (SPS) technique using melt-spun ribbons as starting materials. A distinct two-zone structure with coarse grain zone and fine grain zone was formed in the SPSed magnets. Multi-domain particle in coarse grain zone and exchange interaction domain for fine grain zone were observed. Intergranular non-magnetic phase was favorable to improve the coercivity due to the enhancement of domain wall pinning effects and increased exchange-decouple. The remanent polarization of 0.83 T, coercivity of 1516 kA/m, and maximum energy product of 118 kJ/m{sup 3} are obtained for an isotropic magnet. - Highlights: • Nanocrystalline NdFeB magnets were prepared by spark plasma sintering technique. • Multi-domain particle and exchange interaction domain were observed. • Magnetic microstructure and their relation to the properties were investigated.

  14. Radiative properties of strongly magnetized plasmas

    International Nuclear Information System (INIS)

    Weisheit, J.C.

    1993-11-01

    The influence of strong magnetic fields on quantum phenomena continues to be a topic of much interest to physicists and astronomers investigating a wide array of problems - the formation of high energy-density plasmas in pulsed power experiments, the crustal structure and radiative properties of neutron stars, transport coefficients of matter irradiated by subpicosecond lasers, the spectroscopy of magnetic white dwarf stars, the quantum Hall effect, etc. The passage of time finds more questions being asked than being answered in this subject, where even the hydrogen atom open-quotes paradigmclose quotes remains a major challenge. This theoretical program consists of two distinct parts: (1) investigation into the structure and transport properties of many-electron atoms in fields B > 10 8 Gauss; and (2) extension of spectral lineshape methods for diagnosing fields in strongly magnetized plasmas. Research during the past year continued to be focused on the first topic, primarily because of the interest and skills of Dr. E.P. Lief, the postdoctoral research associate who was hired to work on the proposal

  15. Gas-phase synthesis of magnetic metal/polymer nanocomposites

    Science.gov (United States)

    Starsich, Fabian H. L.; Hirt, Ann M.; Stark, Wendelin J.; Grass, Robert N.

    2014-12-01

    Highly magnetic metal Co nanoparticles were produced via reducing flame spray pyrolysis, and directly coated with an epoxy polymer in flight. The polymer content in the samples varied between 14 and 56 wt% of nominal content. A homogenous dispersion of Co nanoparticles in the resulting nanocomposites was visualized by electron microscopy. The size and crystallinity of the metallic fillers was not affected by the polymer, as shown by XRD and magnetic hysteresis measurements. The good control of the polymer content in the product nanocomposite was shown by elemental analysis. Further, the successful polymerization in the gas phase was demonstrated by electron microscopy and size measurements. The presented effective, dry and scalable one-step synthesis method for highly magnetic metal nanoparticle/polymer composites presented here may drastically decrease production costs and increase industrial yields.

  16. The enhancement of the magnetic properties of α-Fe{sub 2}O{sub 3} nanocatalyst using an external magnetic field for the production of green ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Alqasem, Bilal, E-mail: bilalalqasem@yahoo.com; Yahya, Noorhana, E-mail: noorhana_yahya@petronas.com.my; Qureshi, Saima, E-mail: saima_qureshi_25@yahoo.com; Irfan, Muhammad, E-mail: irfan-mohammad@hotmail.com; Ur Rehman, Zia, E-mail: zia545@hotmail.com; Soleimani, Hassan, E-mail: hassan.soleimani@petronas.com.my

    2017-03-15

    Highlights: • External magnetic field was applied during syntheses of α-Fe{sub 2}O{sub 3} nanocatalyst. • α-Fe{sub 2}O{sub 3} nanocatalyst with enhanced magnetic properties was synthesized. • Effect of magnetic properties and morphology of α-Fe{sub 2}O{sub 3} on ammonia yield was tested. • α-Fe{sub 2}O{sub 3} nanowires with improved saturation magnetization created high ammonia yield. • A maximum green ammonia yield of 24.174 × 10{sup −3} mol h{sup −1} g cat{sup −1} was produced. - Abstract: Hematite nanocatalysts with improved magnetic properties were synthesized using electrical resistive heating under the presence of a magnetic field and a gaseous environment containing oxygen and nitrogen. The synthesis temperature was varied from 500–850 °C in the absence and presence of a static magnetic field of 0.25 T. VSM hysteresis results showed that there is a clear improve in the magnetic properties of the nanocatalysts when an external magnetic field was used during the synthesis. It also showed that the nanowires amongst other shapes hold the highest saturation magnetization value. The produced α-Fe{sub 2}O{sub 3} nanocatalysts were used for ammonia synthesis under an external magnetic field strength ranging between 0.4–2 T. Correspondingly, (24.174 mmol h{sup −1} g cat{sup −1}) ammonia was yielded by applying an external magnetic field of 1.2 T and using the α-Fe{sub 2}O{sub 3} nanowires synthesized at 700 °C with the highest saturation magnetization value of 189.43 emu/g.

  17. Synthesis, characterization and a.c. magnetic analysis of magnetite nanoparticles

    International Nuclear Information System (INIS)

    Riani, P.; Napoletano, M.; Canepa, F.

    2011-01-01

    In the last years, the study of Fe-based magnetic nanoparticles (MNP) has attracted increasing interest either for the physical properties shown by nanosized materials (electric and magnetic properties are strongly affected by dimension and surface effects) either for the different technological applications of these materials (catalysis, drug delivery, magnetic resonance imaging, contaminants removal from groundwater, new exchange coupled magnets, soft nanomagnets for high frequency applications, etc.). In this article, the results obtained in the synthesis and characterization of the Fe 3 O 4 MNP is reported. The magnetite nanoparticles were synthesized by a modified Massart method. Structural characterization was performed using X-ray diffraction analysis and a complete morphological and dimensional study was carried out by means of Transmission Electron Microscopy, and a.c. magnetic susceptibility measured as a function of the frequency of the applied magnetic field. Diameters of the superparamagnetic Fe 3 O 4 nanoparticles are ranging from 2 to 10 nm, as evidenced by all the techniques employed. The size distribution of the hydrated aggregates in solution has been obtained by quantitative analysis of the frequency dependence of the a.c. susceptibility. The mathematical approach adopted will be described and all the obtained results will be compared and discussed.

  18. Crystal structure, magnetic properties and advances in hexaferrites: A brief review

    Science.gov (United States)

    Jotania, Rajshree

    2014-10-01

    Hexaferrites are hard magnetic materials and specifically ferri-magnetic oxides with hexagonal magnetoplumbite type crystallographic structure. Hexagonal ferrites are used as permanent magnets, high-density perpendicular and magneto-optical recording media, and microwave devices like resonance isolators, filters, circulators, phase shifters because of their high magnetic permeability, high electrical resistivity and moderable permittivity. In addition to these; hexagonal ferrites have excellent chemical stability, mechanical hardness and low eddy current loss at high frequencies. The preparation of hexaferrites is a complicated process. Various experimental techniques like standard ceramic techniques, solvent free synthesis route, co precipitation, salt-melt, ion exchange, sol-gel, citrate synthesis, hydrothermal synthesis, spray drying, water-in-oil microemulsion, reverse micelle etc are used to prepare hexaferrite materials. Structural, dielectric and magnetic properties, crystallite size of hexaferrites depend upon nature of substituted ions, method of preparation, sintering temperature and time. The recent interest is nanotechnology, the development of hexaferrite fibres and composites with carbon nano tubes (CNT). Magnetic properties of some doped and un-doped hexaferrites are discussed here. Recent advances in hexaferrites also highlighted in present paper.

  19. Synthesis of ferrite nanoparticle by milling process for preparation of single domain magnet

    International Nuclear Information System (INIS)

    Suryadi; Hasbiyallah; Agus S W; Nurul TR; Budhy Kurniawan

    2009-01-01

    Study of ferrite nanoparticle synthesis for preparation of single domain magnet by milling of scrap magnet material have been done. Sample preparation were done using disk mill continued with high energy milling (HEM). Some powder were taken after 5, 10 dan 20 hours milling using HEM-E3D. The powder were then characterized using X-Ray Fluorescence (XRF), X-Ray Diffractometer (XRD) and Scanning Electron Microscope (SEM). XRF characterization result, confirmed by XRD analysis result, showed that the sample are of Strontium ferrite phase. Microstructure analysis result showed the occurrence of grain refining process of ferrite particle with increasing of milling time. Particle having size of nanometers successfully obtained, although in unhomogeneous distribution. Magnetic properties characterization result showed the increasing of hysteresis curve area of sample for longer milling time and sintering process. (author)

  20. Eco-friendly (green) synthesis of magnetically active gold nanoclusters

    Science.gov (United States)

    Kadasala, Naveen Reddy; Lin, Lu; Gilpin, Christopher; Wei, Alexander

    2017-12-01

    Au-FexOy composite nanoparticles (NPs) are of great technological interest due to their combined optical and magnetic properties. However, typical syntheses are neither simple nor ecologically friendly, creating a challenging situation for process scale-up. Here we describe conditions for preparing Au-FexOy NPs in aqueous solutions and at ambient temperatures, without resorting to solvents or amphiphilic surfactants with poor sustainability profiles. These magnetic gold nanoclusters (MGNCs) are prepared in practical yields with average sizes slightly below 100 nm, and surface plasmon resonances that extend to near-infrared wavelengths, and sufficient magnetic moment (up to 6 emu g-1) to permit collection within minutes by handheld magnets. The MGNCs also produce significant photoluminescence when excited at 488 nm. Energy dispersive X-ray (EDX) analysis indicates a relatively even distribution of Fe within the MGNCs, as opposed to a central magnetic core.

  1. Synthesis, characterization and study of the magnetic properties of Zn_9_1_-_x_)Eu_xO (0,0 ≤ x ≤ 0,035) by combustion reaction

    International Nuclear Information System (INIS)

    Soares, Monica Pereira

    2013-01-01

    Nanocrystallitics of Zinc Oxide containing different amounts of Europium (Zn_(_1_-_x_)Eu_xO - it being 0,0 ≤ x ≤ 0,035) were synthesized by a combustion reaction, with the aim of evaluating the effect of the concentration of Eu"3"+ in magnetic properties, after obtained. The chemical composition was determined by energy dispersive spectroscopy, X-ray (EDS). The structural characterization was performed by X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Spectroscopy Photoelectrons Excited by X-Rays (XPS) and Transmission Electron Microscopy (TEM). Crystalline structure powders of ZnO in wurtzite were formed after the thermal treatment at 550°C about one hour, with average size crystallites of 20 nm. The X-Ray Diffraction results showed presence of diffraction peaks of well-defined of ZnO primary characteristic phase and traces of oxide Europium (Eu_2O_3) as secondary stage for samples doped with 3.5% of Eu"3"+. The analyzes showed the magnetic samples exhibit ferromagnetism at room temperature dependent content of ions Eu"3"+, but for the sample doped with 3.5% Europium the magnetization drops considerably, due to the formation of Oxide Europium (Eu_2O_3) non-magnetic. This fact suggests that the ferromagnetism of samples is associated with the Eu"3"+ ions, it is occupying the interstices of matrix semiconductor wafer. (author)

  2. Recent progress on magnetic iron oxide nanoparticles: synthesis, surface functional strategies and biomedical applications

    Science.gov (United States)

    Wu, Wei; Wu, Zhaohui; Yu, Taekyung; Jiang, Changzhong; Kim, Woo-Sik

    2015-01-01

    This review focuses on the recent development and various strategies in the preparation, microstructure, and magnetic properties of bare and surface functionalized iron oxide nanoparticles (IONPs); their corresponding biological application was also discussed. In order to implement the practical in vivo or in vitro applications, the IONPs must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of IONPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The new functionalized strategies, problems and major challenges, along with the current directions for the synthesis, surface functionalization and bioapplication of IONPs, are considered. Finally, some future trends and the prospects in these research areas are also discussed. PMID:27877761

  3. Synthesis, characterization, and magnetic properties of the new boride solid solutions M{sub 0.5}Ru{sub 6.5}B{sub 3} (M = Cr, Mn, Co, Ni)

    Energy Technology Data Exchange (ETDEWEB)

    Misse, Patrick R.N.; Fokwa, Boniface P.T. [Institute of Inorganic Chemistry, RWTH Aachen University (Germany)

    2010-05-15

    Powder samples and single crystals of the borides M{sub 0.5}Ru{sub 6.5}B{sub 3} (M = Cr, Mn, Co, Ni) were synthesized by arc-melting the elements in a water-cooled copper crucible under argon. The new phases were structurally characterized by single-crystal and powder X-ray diffraction as well as EDX-Analyses. They crystallize in the hexagonal Th{sub 7}Fe{sub 3} structure type (space group P6{sub 3}mc, no. 186, Z = 2) and a pronounced site preferential M/Ru substitution is observed. Magnetic properties of the compounds were investigated and Pauli paramagnetism was observed in all cases. However, a strong temperature dependency is subsequently observed in Mn{sub 0.5}Ru{sub 6.5}B{sub 3} below 250 K, but no hint of magnetic ordering was found. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  4. Synthesis and properties of the diluted magnetic semiconductor ZnO doped with nickel ions by combustion reaction; Sintese e propriedades do semicondutor magnetico diluido ZnO dopado com ions de niquel por meio da reacao de combustao

    Energy Technology Data Exchange (ETDEWEB)

    Morais, A.; Torquato, R.A.; Costa, A.C.F.M, E-mail: m.artur@hotmail.com.br [Universidade Federal da Paraiba (UFPB), Joao Pessoa, PB (Brazil). Departamento de Engenharia de Materiais; Universidade Federal de Campina Grande (UFCG), PB (Brazil). Departamento de Engenharia de Materiais

    2017-10-01

    One of the greatest challenges for the development of the spintronics this creation of materials having semiconductivity and magnetism at above room temperatures, enabling the creation of devices with greater processing speeds. This work aims to synthesize by combustion reaction semiconductor ZnO doped with nickel ions at a concentration of 0.08 mol for applications such as diluted magnetic semiconductor (DMS). The combustion reaction is quite simple and promising in obtaining single-phase materials at the nanoscale. The obtained powder was subjected to the characterizations of X-ray diffraction (XRD), X-ray fluorescence, vibrating sample magnetometry (VSM), and UV-vis spectroscopy. The crystalline material exhibits ZnO crystalline structure and coercive field of 161,36 Oe, showing that the material exhibits the properties of an SMD. (author)

  5. Synthesis of FeSiBPNbCu nanocrystalline soft-magnetic alloys with high saturation magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zongzhen [China Iron and Steel Research Institute Group, Advanced Technology and Materials Co., Ltd., Beijing 100081 (China); Wang, Anding; Chang, Chuntao [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, 519 Zhuangshi Road, Zhenhai District, Ningbo, Zhejiang 315201 (China); Wang, Yanguo [Institute of Physics, Chinese Academy of Sciences, PO Box 603, Beijing 100080 (China); Dong, Bangshao [China Iron and Steel Research Institute Group, Advanced Technology and Materials Co., Ltd., Beijing 100081 (China); Zhou, Shaoxiong, E-mail: sxzhou@atmcn.com [China Iron and Steel Research Institute Group, Advanced Technology and Materials Co., Ltd., Beijing 100081 (China)

    2014-10-25

    Highlights: • Thermal stability of the FeSiBPNbCu alloys is strongly dependent on the Fe content. • The FeSiBPNbCu alloys with high Fe content exhibit good soft magnetic properties. • The coexistence of Cu, P and Nb leads to the excellent soft magnetic properties. - Abstract: A series of [Fe{sub 0.76+x}(Si{sub 0.4}B{sub 0.4}P{sub 0.2}){sub 0.24−x}]{sub 98.25}Nb{sub 1}Cu{sub 0.75} (x = 0–0.08) nanocrystalline soft-magnetic alloys with high saturation magnetization were synthesized by adjusting Fe content and improving the crystallization behavior, soft-magnetic properties and microstructure. It is found that the temperature interval between the two crystallization peaks is significantly enlarged from 50 to 180 °C when the Fe content of the alloys increases from x = 0 to x = 0.08, which greatly expands the optimum annealing temperature range. The alloys with higher Fe content are prone to form more uniform nanocomposite microstructure with better thermal stability and soft magnetic properties. The Fe-rich FeSiBPNbCu nanocrystalline alloys with x = 0.08 exhibit excellent soft-magnetic properties, including the high saturation magnetic flux density of up to 1.74 T, low coercivity of about 3.3 A/m and high effective permeability of more than 2.2 × 10{sup 4} at 1 kHz under a field of 1 A/m. The combination of excellent soft-magnetic properties, low cost and good productivity makes the FeSiBPNbCu alloys to be a kind of promising soft-magnetic materials for electrical and electronic industry applications.

  6. Effect of process on the magnetic properties of bonded NdFeB magnet

    International Nuclear Information System (INIS)

    Li, J.; Liu, Y.; Gao, S.J.; Li, M.; Wang, Y.Q.; Tu, M.J.

    2006-01-01

    The effects of magnetic separation, coupling treatment, lubricating treatment, preform and biaxial molding on the density and magnetic properties of bonded NdFeB magnet were investigated. The results demonstrate that magnetic separation separates the powders with low coercive force; coupling treatment improves the interfaces between the powders and the binders; decrease in volume fraction of the binder increases magnetic properties of the magnet; granular arrangement improves both the magnetic and mechanical properties when powders are arranged in certain size; lubricating treatment improves the formability of the magnet and preform and biaxial molding improves both density and magnetic properties greatly. Combining these methods, the density of the bonded NdFeB magnet can reach 6.52 g/cm 3 and the maximum energy product can reach 114 kJ/m 3

  7. Effect of process on the magnetic properties of bonded NdFeB magnet

    Energy Technology Data Exchange (ETDEWEB)

    Li, J. [School of Materials Science and Engineering, Sichuan University, Chengdu, 610065 (China); Liu, Y. [School of Materials Science and Engineering, Sichuan University, Chengdu, 610065 (China)]. E-mail: liuying5536@163.com; Gao, S.J. [School of Materials Science and Engineering, Sichuan University, Chengdu, 610065 (China); Li, M. [School of Materials Science and Engineering, Sichuan University, Chengdu, 610065 (China); Wang, Y.Q. [South-West Magnetic Science and Technology Developing Company, Mianyang, 621600 (China); Tu, M.J. [School of Materials Science and Engineering, Sichuan University, Chengdu, 610065 (China)

    2006-04-15

    The effects of magnetic separation, coupling treatment, lubricating treatment, preform and biaxial molding on the density and magnetic properties of bonded NdFeB magnet were investigated. The results demonstrate that magnetic separation separates the powders with low coercive force; coupling treatment improves the interfaces between the powders and the binders; decrease in volume fraction of the binder increases magnetic properties of the magnet; granular arrangement improves both the magnetic and mechanical properties when powders are arranged in certain size; lubricating treatment improves the formability of the magnet and preform and biaxial molding improves both density and magnetic properties greatly. Combining these methods, the density of the bonded NdFeB magnet can reach 6.52 g/cm{sup 3} and the maximum energy product can reach 114 kJ/m{sup 3}.

  8. ONE STEP SYNTHESIS OF MAGNETIC PARTICLES COVERED WITH CASEIN SURFACTANT

    Directory of Open Access Journals (Sweden)

    Jeaneth Patricia Urquijo Morales

    Full Text Available The one-step coprecipitation method is used to obtain magnetic nanoparticles controlling the pH (10 and 12, and casein surfactant (CS concentrations (1 % and 3 % (m/m. CS has not been used so far for stabilizing magnetic iron oxide ferrofluids. The magnetic nanoparticles have a magnetite core with maghemite in surface, and a shell of polymer. The transmission electron images confirm the crystallinity, particle size distribution in the range of 5-10 nm, and the spinel structure of the nanoparticles. Mössbauer results at 80 K showed line shapes dominated by magnetic relaxation effects with sextets and combinations of sextets and doublets. The interactions of the surfactant with the nanoparticle surface are strong showing at least two surfactant layers. The magnetic behavior was evaluated by moment versus temperature and magnetic field measurements. The nanoparticles showed superparamagnetic behavior at room temperature and blocked (irreversible behavior at 5 K. The saturation magnetization presented lower values than reported bulk systems due to the presence of a large layer of maghemite. The FC/ZFC magnetization vs. temperature curves confirmed the superparamagnetic nature of the iron oxide particles and the strong interactions for pH 12 samples and weak interactions for pH 10 samples. The particle growth was dominated by the surface properties of the nanoparticles.

  9. Polymer nanotube nanocomposites: synthesis, properties, and applications

    National Research Council Canada - National Science Library

    Mittal, Vikas

    2010-01-01

    ... in these commercially important areas of polymer technology. It sums up recent advances in nanotube composite synthesis technology, provides basic introduction to polymer nanotubes nanocomposite technology for the readers new to this field, provides valuable...

  10. Synthesis, crystal structure determination, thermal and magnetic properties of the new Cu{sub 0.73}Ni{sub 0.27}(HSeO{sub 3}){sub 2} compound

    Energy Technology Data Exchange (ETDEWEB)

    Hentech, I., E-mail: hentechimen@yahoo.fr [Laboratoire des Sciences des Matériaux et de l' Environnement, Faculté des Sciences de Sfax, BP 1171, Université de Sfax, 3000 (Tunisia); CMTR, ICMPE, UMR7182, CNRS – Université Paris Est Créteil, 2-8 rue Henri Dunant, F-94320 Thiais (France); Zehani, K. [CMTR, ICMPE, UMR7182, CNRS – Université Paris Est Créteil, 2-8 rue Henri Dunant, F-94320 Thiais (France); Kabadou, A.; Ben Salah, A.; Loukil, M. [Laboratoire des Sciences des Matériaux et de l' Environnement, Faculté des Sciences de Sfax, BP 1171, Université de Sfax, 3000 (Tunisia); Bessais, L. [CMTR, ICMPE, UMR7182, CNRS – Université Paris Est Créteil, 2-8 rue Henri Dunant, F-94320 Thiais (France)

    2017-01-15

    A novel three-dimensional Cu{sub 0.73}Ni{sub 0.27}(HSeO{sub 3}){sub 2} compound was prepared from an aqueous solution. This compound crystallizes in the monoclinic system with P2{sub 1}/n space group and with the following cell parameters: a=6.4379(3) Å; b=7.3555(3) Å; c=5.7522(3) Å; β=93.4341(1)°; V=271.90(2) Å{sup 3} and Z=2. The reported material has been structurally characterized by X-ray powder diffraction and confirmed by scanning electron microscope and energy dispersive spectroscopy (MEB/EDS) analysis. The copper/nickel atom is surrounded by an octahedron coordination of oxygen atoms from sex hydrogenoselenites anions. The presence of (HSeO{sub 3}){sup −} has been further confirmed by IR spectroscopy and this compound exhibits a phase transition at 356 K, this transition has been detected by differential scanning calorimetry and TG-DTA measurement. The magnetic property of this material was determined. The ferromagnetic ordering is further confirmed by the magnetic field dependence of the magnetization (Hysteresis loop) at 10 K. The substitution of Cu by Ni induces a ferro-paramagnetic transition at T=31 K. Field cooled (FC) and Zero field cooled (ZFC) magnetization measurements under an applied field of 100 Oe in the temperature range of 10–300 K were performed. These measurements have been resulted the blocking temperature (T{sub B}) at around 25 K. - Highlights: • A novel three-dimensional Cu{sub 0.73}Ni{sub 0.27}(HSeO{sub 3}){sub 2} compound was prepared from an aqueous solution. • Magnetic measurements reveal the occurrence of weak ferromagnetism at low temperature for this compound. • The substitution of Cu by Ni induces a ferro-paramagnetic transition at T=31 K.

  11. Synthesis and characterization of uniaxial ferrogels with Ni nanorods as magnetic phase

    International Nuclear Information System (INIS)

    Bender, P.; Guenther, A.; Tschoepe, A.; Birringer, R.

    2011-01-01

    In the present study, the rotation of magnetic nanorods in a soft hydrogel matrix induced by a homogeneous magnetic field is investigated. Magnetic nanorods of ∼151.2nm length and ∼17.7nm diameter are synthesized via current-pulsed electrodeposition of nickel into porous aluminum oxide-templates. The nanorods are processed towards a stable colloidal dispersion by dissolution of the alumina template in aqueous NaOH to which PVP (polyvinyl-pyrrolidone) is added as surfactant. These suspensions are used to prepare gelatine-based ferrogels of different shear modulus with either isotropic or uniaxial orientation-distribution of the nanorods. While magnetization measurements of rigid ferrogels mainly reflect the magnetic properties of the nickel nanorods, the magnetization behavior of soft ferrogels is significantly influenced by a field-induced rotation of the nickel nanorods in the low compliant matrix. A particular analysis of magnetization measurements on uniaxial ferrogels enables to quantify the rotation angle of the nanorods with respect to their initial orientation under the influence of a transversal homogeneous magnetic field. The analysis of the field-dependent rotation also allows to estimate the local shear modulus of the matrix which is demonstrated by an investigation of room temperature ageing process of the ferrogel. - Highlights: → We present the synthesis of ferrogels containing ferromagnetic Ni nanorods. → The torque in the homogeneous magnetic field leads to a rotation of the nanorods. → The rotation angle increases with decreasing shear modulus of the gel matrix. → The local shear modulus can be estimated by analyzing magnetization measurements.

  12. Synthesis and reaction of [[HC(CMeNAr)2]Mn]2 (Ar = 2,6-iPr2C6H3): the complex containing three-coordinate manganese(I) with a Mn-Mn bond exhibiting unusual magnetic properties and electronic structure.

    Science.gov (United States)

    Chai, Jianfang; Zhu, Hongping; Stückl, A Claudia; Roesky, Herbert W; Magull, Jörg; Bencini, Alessandro; Caneschi, Andrea; Gatteschi, Dante

    2005-06-29

    This paper reports on the synthesis, X-ray structure, magnetic properties, and DFT calculations of [[HC(CMeNAr)2]Mn]2 (Ar = 2,6-iPr2C6H3) (2), the first complex with three-coordinate manganese(I). Reduction of the iodide [[HC(CMeNAr)2]Mn(mu-I)]2 (1) with Na/K in toluene afforded 2 as dark-red crystals. The molecule of 2 contains a Mn2(2+) core with a Mn-Mn bond. The magnetic investigations show a rare example of a high-spin manganese(I) complex with an antiferromagnetic interaction between the two Mn(I) centers. The DFT calculations indicate a strong s-s interaction of the two Mn(I) ions with the open shell configuration (3d54s1). This suggests that the magnetic behavior of 2 could be correctly described as the coupling between two S1 = S2 = 5/2 spin centers. The Mn-Mn bond energy is estimated at 44 kcal mol(-1) by first principle calculations with the B3LYP functional. The further oxidative reaction of 2 with KMnO4 or O2 resulted in the formation of manganese(III) oxide [[HC(CMeNAr)2]Mn(mu-O)]2 (3). Compound 3 shows an antiferromagnetic coupling between the two oxo-bridged manganese(III) centers by magnetic measurements.

  13. Synthesis of micro-sized polystyrene magnetic particles

    International Nuclear Information System (INIS)

    Neves, Juliete S.; Suarez, Paulo A.Z.; Umpierre, Alexandre P.; Machado, Fabricio; Souza Junior, Fernando G. de

    2011-01-01

    The present work illustrates the synthesis of spherical and micro-sized polystyrene magnetic particles by using a water-based suspension polymerization process to incorporate in situ surface modified superparamagnetic Fe 3 O 4 nanoparticles. The crystallite size of Fe 3 O 4 was determined to be equal to 7.7 nm, based on Scherrer's equation and XRD measurement. According to EDX analyses, Fe 3 O 4 / polystyrene nanocomposites particles show strong characteristic peaks Kα and Kβ of iron at the interval from 6.38 KeV to 7.04 KeV with an amount of iron in the samples equal to 98 %, indicating that the inorganic material dispersed in the polystyrene matrix is essentially Fe in the form of iron oxide (Fe 3 O 4 ). The obtained polymeric materials presented good magnetic behavior, indicating that the modified Fe 3 O 4 nanoparticles were successfully dispersed in the polystyrene particles. (author)

  14. Magnetic properties of Proxima Centauri b analogues

    Science.gov (United States)

    Zuluaga, Jorge I.; Bustamante, Sebastian

    2018-03-01

    The discovery of a planet around the closest star to our Sun, Proxima Centauri, represents a quantum leap in the testability of exoplanetary models. Unlike any other discovered exoplanet, models of Proxima b could be contrasted against near future telescopic observations and far future in-situ measurements. In this paper we aim at predicting the planetary radius and the magnetic properties (dynamo lifetime and magnetic dipole moment) of Proxima b analogues (solid planets with masses of ∼ 1 - 3M⊕ , rotation periods of several days and habitable conditions). For this purpose we build a grid of planetary models with a wide range of compositions and masses. For each point in the grid we run the planetary evolution model developed in Zuluaga et al. (2013). Our model assumes small orbital eccentricity, negligible tidal heating and earth-like radiogenic mantle elements abundances. We devise a statistical methodology to estimate the posterior distribution of the desired planetary properties assuming simple lprior distributions for the orbital inclination and bulk composition. Our model predicts that Proxima b would have a mass 1.3 ≤Mp ≤ 2.3M⊕ and a radius Rp =1.4-0.2+0.3R⊕ . In our simulations, most Proxima b analogues develop intrinsic dynamos that last for ≥4 Gyr (the estimated age of the host star). If alive, the dynamo of Proxima b have a dipole moment ℳdip >0.32÷2.9×2.3ℳdip , ⊕ . These results are not restricted to Proxima b but they also apply to earth-like planets having similar observed properties.

  15. Synthesis and characterization of core–shell magnetic molecularly ...

    Indian Academy of Sciences (India)

    of hormones [24] or chemical compounds [25] and colour identification [26]. ... The magnetic properties were analysed with a vibrating sample magnetometer .... Transmission electron microscopy image of (a) Fe3O4 and (b) Fe3O4@SiO2.

  16. Self-propagating high temperature synthesis and magnetic ...

    Indian Academy of Sciences (India)

    Unknown

    phase composition, microstructure and magnetic properties of the combustion products. The effect ... The size and shapes of the ... Figure 3 shows the effect of combustion temperature on ... ducts at 1200°C are too hard to be ground easily and.

  17. Nanosilicon properties, synthesis, applications, methods of analysis and control

    CERN Document Server

    Ischenko, Anatoly A; Aslalnov, Leonid A

    2015-01-01

    Nanosilicon: Properties, Synthesis, Applications, Methods of Analysis and Control examines the latest developments on the physics and chemistry of nanosilicon. The book focuses on methods for producing nanosilicon, its electronic and optical properties, research methods to characterize its spectral and structural properties, and its possible applications. The first part of the book covers the basic properties of semiconductors, including causes of the size dependence of the properties, structural and electronic properties, and physical characteristics of the various forms of silicon. It presents theoretical and experimental research results as well as examples of porous silicon and quantum dots. The second part discusses the synthesis of nanosilicon, modification of the surface of nanoparticles, and properties of the resulting particles. The authors give special attention to the photoluminescence of silicon nanoparticles. The third part describes methods used for studying and controlling the structure and pro...

  18. Effects Of Hydrothermal Alteration On Magnetic Properties And Magnetic Signatures - Implications For Predictive Magnetic Exploration Models

    Science.gov (United States)

    Clark, D.

    2012-12-01

    Magnetics is the most widely used geophysical method in hard rock exploration and magnetic surveys are an integral part of exploration programs for many types of mineral deposit, including porphyry Cu, intrusive-related gold, volcanic-hosted epithermal Au, IOCG, VMS, and Ni sulfide deposits. However, the magnetic signatures of ore deposits and their associated mineralized systems are extremely variable and exploration that is based simply on searching for signatures that resemble those of known deposits and systems is rarely successful. Predictive magnetic exploration models are based upon well-established geological models, combined with magnetic property measurements and geological information from well-studied deposits, and guided by magnetic petrological understanding of the processes that create, destroy and modify magnetic minerals in rocks. These models are designed to guide exploration by predicting magnetic signatures that are appropriate to specific geological settings, taking into account factors such as tectonic province; protolith composition; post-formation tilting/faulting/ burial/ exhumation and partial erosion; and metamorphism. Patterns of zoned hydrothermal alteration are important indicators of potentially mineralized systems and, if properly interpreted, can provided vectors to ore. Magnetic signatures associated with these patterns at a range of scales can provide valuable information on prospectivity and can guide drilling, provided they are correctly interpreted in geological terms. This presentation reviews effects of the important types of hydrothermal alteration on magnetic properties within mineralized systems, with particular reference to porphyry copper and IOCG deposits. For example, an unmodified gold-rich porphyry copper system, emplaced into mafic-intermediate volcanic host rocks (such as Bajo de la Alumbrera, Argentina) exhibits an inner potassic zone that is strongly mineralized and magnetite-rich, which is surrounded by an outer

  19. Magnetic properties of NiMn2O4−δ (nickel manganite): Multiple magnetic phase transitions and exchange bias effect

    International Nuclear Information System (INIS)

    Tadic, Marin; Savic, S.M.; Jaglicic, Z.; Vojisavljevic, K.; Radojkovic, A.; Prsic, S.; Nikolic, Dobrica

    2014-01-01

    Highlights: • We have successfully synthesized NiMn 2 O 4−δ sample by complex polymerization synthesis. • Magnetic measurements reveal complex properties and triple magnetic phase transitions. • Magnetic measurements of M(H) show hysteretic behavior below 120 K. • Hysteresis properties after cooling of the sample in magnetic field show exchange bias effect. -- Abstract: We present magnetic properties of NiMn 2 O 4−δ (nickel manganite) which was synthesized by complex polymerization synthesis method followed by successive heat treatment and final calcinations in air at 1200 °C. The sample was characterized by using X-ray powder diffractometer (XRPD), scanning electron microscopy (SEM), field-emission scanning electron microscopy (FE-SEM) and superconducting quantum interference device (SQUID) magnetometer. The XRPD and FE-SEM studies revealed NiMn 2 O 4−δ phase and good crystallinity of particles. No other impurities have been observed by XRPD. The magnetic properties of the sample have been studied by measuring the temperature and field dependence of magnetization. Magnetic measurements of M(T) reveal rather complex magnetic properties and multiple magnetic phase transitions. We show three magnetic phase transitions with transition temperatures at T M1 = 35 K (long-range antiferromagnetic transition), T M2 = 101 K (antiferromagnetic-type transition) and T M3 = 120 K (ferromagnetic-like transition). We found that the T M1 transition is strongly dependent on the strength of the applied magnetic field (T M1 decreases with increasing applied field) whereas the T M3 is field independent. Otherwise, the T M2 maximum almost disappears in higher applied magnetic fields (H = 1 kOe and 10 kOe). Magnetic measurements of M(H) show hysteretic behavior below T M3 . Moreover, hysteresis properties measured after cooling of the sample in magnetic field of 10 kOe show exchange bias effect with an exchange bias field |H EB |=196 Oe. In summary, the properties that

  20. High-pressure synthesis, crystal structure, and magnetic properties of KSbO3-type 5d oxides K0.84OsO3 and Bi2.93Os3O11

    Science.gov (United States)

    Yuan, Yahua; Feng, Hai L.; Shi, Youguo; Tsujimoto, Yoshihiro; Belik, Alexei A.; Matsushita, Yoshitaka; Arai, Masao; He, Jianfeng; Tanaka, Masahiko; Yamaura, Kazunari

    2014-12-01

    5d Solid-state oxides K0.84OsO3 (Os5.16+; 5d 2.84) and Bi2.93Os3O11 (Os4.40+; 5d 3.60) were synthesized under high-pressure and high-temperature conditions (6 GPa and 1500-1700 °C). Their crystal structures were determined by synchrotron x-ray diffraction and their 5d electronic properties and tunnel-like structure motifs were investigated. A KSbO3-type structure with a space group of Im-3 and Pn-3 was determined for K0.84OsO3 and Bi2.93Os3O11, respectively. The magnetic and electronic transport properties of the polycrystalline compounds were compared with those obtained theoretically. It was revealed that the 5d tunnel-like structures are paramagnetic with metallic charge conduction at temperatures above 2 K. This was similar to what was observed for structurally relevant 5d oxides, including Bi3Re3O11 (Re4.33+; 5d 2.66) and Ba2Ir3O9 (Ir4.66+; 5d 4.33). The absence of long-range magnetic order seems to be common among 5d KSbO3-like oxides, regardless of the number of 5d electrons (between 2.6 and 4.3 per 5d atom).

  1. Plasma synthesis of nanostructures for improved thermoelectric properties

    International Nuclear Information System (INIS)

    Petermann, Nils; Hecht, Christian; Schulz, Christof; Wiggers, Hartmut; Stein, Niklas; Schierning, Gabi; Theissmann, Ralf; Stoib, Benedikt; Brandt, Martin S

    2011-01-01

    The utilization of silicon-based materials for thermoelectrics is studied with respect to the synthesis and processing of doped silicon nanoparticles from gas phase plasma synthesis. It is found that plasma synthesis enables the formation of spherical, highly crystalline and soft-agglomerated materials. We discuss the requirements for the formation of dense sintered bodies, while keeping the crystallite size small. Small particles a few tens of nanometres and below that are easily achievable from plasma synthesis, and a weak surface oxidation, both lead to a pronounced sinter activity about 350 K below the temperature usually needed for the successful densification of silicon. The thermoelectric properties of our sintered materials are comparable to the best results found for nanocrystalline silicon prepared by methods other than plasma synthesis.

  2. Obtaining Magnetic Properties of Meteorites Using Magnetic Scanner

    Science.gov (United States)

    Kletetschka, G.; Nabelek, L.; Mazanec, M.; Simon, K.; Hruba, J.

    2015-12-01

    Magnetic images of Murchison meteorite's and Chelyabinsk meteorite's thin section have been obtained from magnetic scanning system from Youngwood Science and Engineering (YSE) capable of resolving magnetic anomalies down to 10-3 mT range from about 0.3 mm distance between the probe and meteorite surface (resolution about 0.15 mm). Anomalies were produced repeatedly, each time after application of magnetic field pulse of varying amplitude and constant, normal or reversed, direction. This process resulted in both magnetizing and demagnetizing of the meteorite thin section, while keeping the magnetization vector in the plane of the thin section. Analysis of the magnetic data allows determination of coercivity of remanence (Bcr) for the magnetic sources in situ. Value of Bcr is critical for calculating magnetic forces applicable during missions to asteroids where gravity is compromised. Bcr was estimated by two methods. First method measured varying dipole magnetic field strength produced by each anomaly in the direction of magnetic pulses. Second method measured deflections of the dipole direction from the direction of magnetic pulses (Nabelek et al., 2015). Nabelek, L., Mazanec, M., Kdyr, S., and Kletetschka, G., 2015, Magnetic, in situ, mineral characterization of Chelyabinsk meteorite thin section: Meteoritics & Planetary Science.

  3. Magnetic properties of GdMnO3 nanoparticles embedded in mesoporous silica

    Science.gov (United States)

    Tajiri, Takayuki; Mito, Masaki; Deguchi, Hiroyuki; Kohno, Atsushi

    2018-05-01

    Perovskite manganite GdMnO3 nanoparticles were synthesized using mesoporous silica as a template, and their magnetic properties and crystal structure were investigated. Powder X-ray diffraction data indicated successful synthesis of the GdMnO3 nanoparticles, with mean particle sizes of 13.9 and 20.9 nm. The lattice constants for the nanoparticles were slightly different from those for the bulk material and varied with the particle size. The magnetic transition temperatures for the nanoparticles were higher than those of the bulk crystal. The synthesized GdMnO3 nanoparticles exhibited superparamagnetic behaviors: The blocking temperature, coercive field, and transition temperature depended on the particle size. Magnetic measurements and crystal structure analysis suggest that the changes in the magnetic properties for GdMnO3 nanoparticles can be attributed to the modulation of the crystallographic structure.

  4. Lanthanide phosphonates: Synthesis, thermal stability and magnetic characterization

    Energy Technology Data Exchange (ETDEWEB)

    Amghouz, Z., E-mail: amghouz.uo@uniovi.es [Departamentos de Quimica Fisica y Analitica y Quimica Organica e Inorganica, Universidad de Oviedo - CINN, 33006 Oviedo (Spain); Garcia, J.R.; Garcia-Granda, S. [Departamentos de Quimica Fisica y Analitica y Quimica Organica e Inorganica, Universidad de Oviedo - CINN, 33006 Oviedo (Spain); Clearfield, A. [Department of Chemistry, Texas A and M University, College Station, TX 77842-3012 (United States); Rodriguez Fernandez, J.; Pedro, I. de [CITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander (Spain); Blanco, J.A. [Departamento de Fisica, Universidad de Oviedo, 33007 Oviedo (Spain)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Report of the complete series of lanthanide 1,4-phenylbis(phosphonate). Black-Right-Pointing-Pointer Synthesis under conventional hydrothermal synthesis or microwave-assisted hydrothermal synthesis. Black-Right-Pointing-Pointer Cation size is the key factor for the structural and particles size variations. Black-Right-Pointing-Pointer Thermal behaviour is characterized by unusual very high thermal stability. - Abstract: Series of novel organic-inorganic hybrids materials based on trivalent lanthanides (Ln = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) and 1,4-phenylbis(phosphonate) obtained under hydrothermal conditions either by oven heat or microwave irradiation. The anhydrous compounds containing La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Ho, are isostructural. However, the compounds based on Y, Er, Tm, Yb, and Lu are hydrated and their structures have not yet been solved. The series of compounds are characterized by PXRD, TEM, SEM-EDX and thermal analyses (TG-MS and DSC). TEM study show a variable particles size with a minimum mean-particle size of ca. 30 nm. These compounds exhibit unusual very high thermal stability. The size of particles and the thermal stability are depending on lanthanide(III) cation features. All the investigated materials show paramagnetic behaviour. The magnetic susceptibility data follow a Curie-Weiss laws with paramagnetic effective moments in good agreement with those expected for Ln{sup 3+} free ions.

  5. Síntese e caracterização de copolímeros à base de metacrilato de metila e divinilbenzeno com propriedades magnéticas Synthesis and characterization of copolymers based on methyl methacrylate and divinylbenzene with magnetic properties

    Directory of Open Access Journals (Sweden)

    Cristiane N. Costa

    2012-01-01

    Full Text Available Neste trabalho, foram sintetizados materiais binários baseados em copolímeros de metacrilato de metila reticulados com divinilbenzeno contendo partículas de ferro com propriedades magnéticas pela técnica de polimerização em suspensão. Foram estudados os efeitos da concentração de ferro adicionado na polimerização, da razão molar MMA/DVB, do tipo de agente de suspensão e da velocidade de agitação na formação do copolímero. Os copolímeros foram caracterizados quanto à morfologia, à estabilidade térmica, ao teor de ferro incorporado, à distribuição de tamanho de partículas, às propriedades magnéticas, à área superficial, ao volume e ao tamanho de poros. Foram obtidas microesferas poliméricas com propriedades magnéticas que apresentaram bom controle morfológico esférico e partículas de ferro aglomeradas por toda a superfície da microesfera. As análises de propriedades magnéticas mostraram que os materiais obtidos não apresentaram ciclos de histerese, estando assim próximos de um material com propriedades superparamagnéticas, com magnetização de saturação entre 8,0 e 13,0 emu.g-1.In this work, copolymers based on methyl methacrylate and divinylbenzene containing iron with magnetic properties were produced using the suspension polymerization method. An investigation was performed of the effect from the concentration of iron added to the polymerization, the MMA/DVB molar ratio in the copolymer formation, type of suspension agent and stirring speed on the synthesis of the copolymers. The copolymers morphology, thermal stability, contents of embedded iron, particle size distribution, magnetic properties, surface area, volume and pore size were evaluated. Polymeric microspheres with magnetic properties were successfully obtained. These materials showed good control of the spherical shape and agglomeration of iron particles under the surface of the microsphere. The analysis of magnetic properties pointed to

  6. Synthesis, microstructures and properties of {gamma}-aluminum oxynitride

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xidong; Wang Fuming; Li Wenchao

    2003-02-15

    This paper deals with the synthesis, microstructures and properties of {gamma}-aluminum oxynitride (AlON). The thermodynamic properties of AlON were analyzed and the Gibbs energy of AlON with different compositions and temperatures were evaluated. Based on thermodynamic studies, AlON has been synthesized. The microstructures, mechanical properties and oxidation resistance of the synthetic AlON have been examined and discussed.

  7. Magnetic properties of frictional volcanic materials

    Science.gov (United States)

    Kendrick, Jackie E.; Lavallée, Yan; Biggin, Andrew; Ferk, Annika; Leonhardt, Roman

    2015-04-01

    During dome-building volcanic eruptions, highly viscous magma extends through the upper conduit in a solid-like state. The outer margins of the magma column accommodate the majority of the strain, while the bulk of the magma is able to extrude, largely undeformed, to produce magma spines. Spine extrusion is often characterised by the emission of repetitive seismicity, produced in the upper <1 km by magma failure and slip at the conduit margins. The rheology of the magma controls the depth at which fracture can occur, while the frictional properties of the magma are important in controlling subsequent marginal slip processes. Upon extrusion, spines are coated by a carapace of volcanic fault rocks which provide insights into the deeper conduit processes. Frictional samples from magma spines at Mount St. Helens (USA), Soufriere Hills (Montserrat) and Mount Unzen (Japan) have been examined using structural, thermal and magnetic analyses to reveal a history of comminution, frictional heating, melting and cooling to form volcanic pseudotachylyte. Pseudotachylyte has rarely been noted in volcanic materials, and the recent observation of its syn-eruptive formation in dome-building volcanoes was unprecedented. The uniquely high thermal conditions of volcanic environments means that frictional melt remains at elevated temperatures for longer than usual, causing slow crystallisation, preventing the development of some signature "quench" characteristics. As such, rock-magnetic tests have proven to be some of the most useful tools in distinguishing pseudotachylytes from their andesite/ dacite hosts. In volcanic pseudotachylyte the mass normalised natural remanent magnetisation (NRM) when further normalised with the concentration dependent saturation remanence (Mrs) was found to be higher than the host rock. Remanence carriers are defined as low coercive materials across all samples, and while the remanence of the host rock displays similarities to an anhysteretic remanent

  8. Properties of pseudo magnetism acting between bodies

    Directory of Open Access Journals (Sweden)

    Anish Deva

    Full Text Available A non-contact force has been found to be always acting between two bodies kept close to each other in different media. The properties of the force are different as compared to other non-contact forces such as gravitation and electrostatics, as was shown in our previous work. The aim of this paper is to find how the force behaves when two objects are brought near each other, one being completely immersed in the medium and the other kept just outside. The magnitude of the force in each medium has been calculated through experiments and then compared with each other. The discrepancies obtained between these magnitudes (10−5 N in water and 10−6 N in engine oil and the varied oscillation patterns (amplitude and frequency obtained from graphs have shown that the force behaves differently with different media. In general, the frequency of the force has been found to be of the order 10−2 Hz. The behaviour has also been found to depend on the nature of the material and shape of the object. This correlation has been ascertained by using a Gauss meter to measure the force acting between two objects and also that of an individual object. The polarity of the force i.e. whether attractive or repulsive, has been found to vary across the length of the objects and graphs have been plotted to demonstrate this property. Keywords: Non-contact force, Medium, Magnetism, Gravitation, Frequency

  9. Synthesis, crystal structure and magnetic properties of (acetato-κ²O,O')bis(5,5'-dimethyl-2,2'-bipyridine-κ²N,N')nickel(II) perchlorate monohydrate.

    Science.gov (United States)

    Farkašová, Nela; Černák, Juraj; Falvello, Larry R; Orendáč, Martin; Boča, Roman

    2015-04-01

    The title hydrated ionic complex, [Ni(CH3COO)(C12H12N2)2]ClO4·H2O or [Ni(ac)(5,5'-dmbpy)2]ClO4·H2O (where 5,5'-dmbpy is 5,5'-dimethyl-2,2'-bipyridine and ac is acetate), (1), was isolated as violet crystals from the aqueous ethanolic nickel acetate-5,5'-dmbpy-KClO4 system. Within the complex cation, the Ni(II) atom is hexacoordinated by two chelating 5,5'-dmbpy ligands and one chelating ac ligand. The mean Ni-N and Ni-O bond lengths are 2.0628 (17) and 2.1341 (15) Å, respectively. The water solvent molecule is disordered over two partially occupied positions and links two complex cations and two perchlorate anions into hydrogen-bonded centrosymmetric dimers, which are further connected by π-π interactions. The magnetic properties of (1) at low temperatures are governed by the action of single-ion anisotropy, D, which arises from the reduced local symmetry of the cis-NiO2N4 chromophore. The fitting of the variable-temperature magnetic data (2-300 K) gives g(iso) = 2.134 and D/hc = 3.13 cm(-1).

  10. L-arginine modified magnetic nanoparticles: green synthesis and characterization

    Science.gov (United States)

    Bagherpour, A. R.; Kashanian, F.; Seyyed Ebrahimi, S. A.; Habibi-Rezaei, M.

    2018-02-01

    In recent years, there has been considerable interest in Arg which is a unique, nontoxic, and biocompatible biomolecule since it can be utilized as an agent for the functionalization and subsequent stabilization of MNPs against oxidation and aggregation, during or after a synthesis procedure. Our studies demonstrate that Arg has great impacts on MNPs with the decreasing size of the particle. Also, saturation magnetization and electrostatic interactions of RMNPs have a direct impact on biological molecules such as proteins and nucleic acids. By controlling the concentration of Arg, it is possible to accurately control the above-mentioned characteristics, which are useful tools for applications such as connecting to antibodies, catalysis, drug loading, and modification of MNP stability. In the current study, three RMNPs with different Arg densities, i.e. 0.42, 1.62, and 2.29 μg per mg were successfully synthesized through a simple co-precipitation method (named p 0.5, p 1, and p 1.5, respectively) and verified by colorimetric determination. Also, the as-synthesized RMNP powders were characterized by XRD, SEM/EDAX, FTIR, VSM, and zeta potential analysis. The presence of a magnetic core was proved by XRD, FTIR, and EDAX. Colorimetric analysis showed the existence of Arg in the synthesized samples. According to the zeta potential and VSM results, increasing the cap of Arg on the MNP surface leads to an increase in the surface charge and decrease in the magnetization of the RMNPs, respectively.

  11. Effect of annealing process of iron powder on magnetic properties ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Iron powder magnetic cores are used as soft magnetic rotors, in micro special motors such as BS brake motors, refrigerator compressor motors and brushless servo motors. Heat treatment of iron powder played an important role in the magnetic properties and loss of the motor cores. After the annealing process,.

  12. Electrical Machines Laminations Magnetic Properties: A Virtual Instrument Laboratory

    Science.gov (United States)

    Martinez-Roman, Javier; Perez-Cruz, Juan; Pineda-Sanchez, Manuel; Puche-Panadero, Ruben; Roger-Folch, Jose; Riera-Guasp, Martin; Sapena-Baño, Angel

    2015-01-01

    Undergraduate courses in electrical machines often include an introduction to their magnetic circuits and to the various magnetic materials used in their construction and their properties. The students must learn to be able to recognize and compare the permeability, saturation, and losses of these magnetic materials, relate each material to its…

  13. Redox-active porous coordination polymers prepared by trinuclear heterometallic pivalate linking with the redox-active nickel(II) complex: synthesis, structure, magnetic and redox properties, and electrocatalytic activity in organic compound dehalogenation in heterogeneous medium.

    Science.gov (United States)

    Lytvynenko, A S; Kolotilov, S V; Kiskin, M A; Cador, O; Golhen, S; Aleksandrov, G G; Mishura, A M; Titov, V E; Ouahab, L; Eremenko, I L; Novotortsev, V M

    2014-05-19

    Linking of the trinuclear pivalate fragment Fe2CoO(Piv)6 by the redox-active bridge Ni(L)2 (compound 1; LH is Schiff base from hydrazide of 4-pyridinecarboxylic acid and 2-pyridinecarbaldehyde, Piv(-) = pivalate) led to formation of a new porous coordination polymer (PCP) {Fe2CoO(Piv)6}{Ni(L)2}1.5 (2). X-ray structures of 1 and 2 were determined. A crystal lattice of compound 2 is built from stacked 2D layers; the Ni(L)2 units can be considered as bridges, which bind two Fe2CoO(Piv)6 units. In desolvated form, 2 possesses a porous crystal lattice (SBET = 50 m(2) g(-1), VDR = 0.017 cm(3) g(-1) estimated from N2 sorption at 78 K). At 298 K, 2 absorbed a significant quantity of methanol (up to 0.3 cm(3) g(-1)) and chloroform. Temperature dependence of molar magnetic susceptibility of 2 could be fitted as superposition of χMT of Fe2CoO(Piv)6 and Ni(L)2 units, possible interactions between them were taken into account using molecular field model. In turn, magnetic properties of the Fe2CoO(Piv)6 unit were fitted using two models, one of which directly took into account a spin-orbit coupling of Co(II), and in the second model the spin-orbit coupling of Co(II) was approximated as zero-field splitting. Electrochemical and electrocatalytic properties of 2 were studied by cyclic voltammetry in suspension and compared with electrochemical and electrocatalytic properties of a soluble analogue 1. A catalytic effect was determined by analysis of the catalytic current dependency on concentrations of the substrate. Compound 1 possessed electrocatalytic activity in organic halide dehalogenation, and such activity was preserved for the Ni(L)2 units, incorporated into the framework of 2. In addition, a new property occurred in the case of 2: the catalytic activity of PCP depended on its sorption capacity with respect to the substrate. In contrast to homogeneous catalysts, usage of solid PCPs may allow selectivity due to porous structure and simplify separation of product.

  14. Properties and practical performance of SC magnets in accelerators

    International Nuclear Information System (INIS)

    Schmueser, P.

    1992-01-01

    A report is given on the properties and performance of superconducting accelerator magnets in the 5-6 Tesla regime. Most of the information stems from the industrially produced HERA magnets which were thoroughly tested both at industry and at DESY; data from prototype magnets for RHIC and SSC are also included. Persistent current effects were studied in detail. During the commissioning of the proton-electron collider HERA the superconducting magnets worked with high reliability and their properties were exactly as predicted from the magnetic measurements. (author) 11 refs.; 8 figs

  15. Hydrothermal synthesis and physicochemical properties of ruthenium(0) nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Dikhtiarenko, A., E-mail: dikhtiarenkoalla@uniovi.es [Departamento de Quimica Organica e Inorganica, Universidad de Oviedo - CINN, 33006 Oviedo (Spain); Khainakov, S.A.; Garcia, J.R.; Gimeno, J. [Departamento de Quimica Organica e Inorganica, Universidad de Oviedo - CINN, 33006 Oviedo (Spain); Pedro, I. de; Fernandez, J. Rodriguez [CITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander (Spain); Blanco, J.A. [Departamento de Fisica, Universidad de Oviedo, 33007 Oviedo (Spain)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Ruthenium nanoparticles were synthesized by hydrothermal technique. Black-Right-Pointing-Pointer The average size of the nanoparticles are depend on the reducing agent used. Black-Right-Pointing-Pointer The magnetic response seems to be dominated by a paramagnetic contribution characteristic of the band electronic magnetism of the ruthenium(0) nanoparticles. - Abstract: The synthesis of ruthenium nanoparticles in hydrothermal conditions using mild reducing agents (succinic acid, ascorbic acid and sodium citrate) is reported. The shape of the nanoparticles depends on the type of the reducing agent, while the size is more influenced by the pH of the medium. The magnetic response seems to be dominated by a paramagnetic contribution characteristic of the band electronic magnetism of the nanoparticles.

  16. Phase controlled synthesis of (Mg, Ca, Ba)-ferrite magnetic nanoparticles with high uniformity

    International Nuclear Information System (INIS)

    Wang, S.F.; Li, Q.; Zu, X.T.; Xiang, X.; Liu, W.; Li, S.

    2016-01-01

    (Mg, Ca, Ba)-ferrite magnetic nanoparticles were successfully synthesized through modifying the atomic ratio of polysaccharide and chelating agent at an optimal sintering temperature. In the process, the polysaccharide plays an important role in drastically shrinking the precursor during the gel drying process. In the metal-complex structure, M"2"+ ion active sites were coordinated by −OH of the water molecules except for EDTA anions. The MFe_2O_4 magnetic nanoparticles exhibited enhanced magnetic properties when compared with nano-MFe_2O_4 of similar particle size synthesized by other synthesis route reported in the literature. In particular, the sintering temperature improves the crystallinity and increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles significantly. - Graphical abstract: Schematic representation of the proposed model for MFe_2O_4 nanoparticle synthesis, starting from EDTA-chelated M"2"+ (M=Mg, Ca, or Ba) cations (left). High dispersion (Mg, Ca, Ba)-ferrite magnetic nanoparticles were prepared by a modified polyacrylamide gel route. Optimized utilization of polysaccharide, chelating agent, and sintering temperature allowed the formation of (Mg, Ca, Ba)-ferrite nanoparticles with a narrow diameter distribution. - Highlights: • We report a modified polyacrylamide gel route to synthesize (Mg, Ca, Ba)-ferrite magnetic nanoparticles. • Chelate mechanism of metal ions (Mg, Ca, Ba) and EDTA has been discussed. • Phase transformation process of (Mg, Ca, Ba)-ferrites has been discussed. • The preparation method increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles.

  17. Phase controlled synthesis of (Mg, Ca, Ba)-ferrite magnetic nanoparticles with high uniformity

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S.F., E-mail: wangshifa2006@yeah.net [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Science and technology on vacuum technology and physics laboratory, Lanzhou Institute of Physics, Lanzhou 730000, Gansu (China); Li, Q. [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Zu, X.T., E-mail: xtzu@uestc.edu.cn [Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Xiang, X.; Liu, W. [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Li, S., E-mail: sean.li@unsw.edu.au [School of Material Science and Engineering, University of New South Wales, Sydney 2052 (Australia)

    2016-12-01

    (Mg, Ca, Ba)-ferrite magnetic nanoparticles were successfully synthesized through modifying the atomic ratio of polysaccharide and chelating agent at an optimal sintering temperature. In the process, the polysaccharide plays an important role in drastically shrinking the precursor during the gel drying process. In the metal-complex structure, M{sup 2+} ion active sites were coordinated by −OH of the water molecules except for EDTA anions. The MFe{sub 2}O{sub 4} magnetic nanoparticles exhibited enhanced magnetic properties when compared with nano-MFe{sub 2}O{sub 4} of similar particle size synthesized by other synthesis route reported in the literature. In particular, the sintering temperature improves the crystallinity and increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles significantly. - Graphical abstract: Schematic representation of the proposed model for MFe{sub 2}O{sub 4} nanoparticle synthesis, starting from EDTA-chelated M{sup 2+} (M=Mg, Ca, or Ba) cations (left). High dispersion (Mg, Ca, Ba)-ferrite magnetic nanoparticles were prepared by a modified polyacrylamide gel route. Optimized utilization of polysaccharide, chelating agent, and sintering temperature allowed the formation of (Mg, Ca, Ba)-ferrite nanoparticles with a narrow diameter distribution. - Highlights: • We report a modified polyacrylamide gel route to synthesize (Mg, Ca, Ba)-ferrite magnetic nanoparticles. • Chelate mechanism of metal ions (Mg, Ca, Ba) and EDTA has been discussed. • Phase transformation process of (Mg, Ca, Ba)-ferrites has been discussed. • The preparation method increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles.

  18. The effect of saturation magnetization of nanocatalyst and oscillating magnetic field for green urea synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Yahya, Noorhana, E-mail: noorhana_yahya@petronas.com.my; Alqasem, Bilal, E-mail: bilalalqasem@yahoo.com; Irfan, Muhammad; Qureshi, Saima; Rehman, Zia Ur; Shafie, Afza; Soleimani, Hassan

    2017-02-15

    Hematite and cupric oxide nanowires have been synthesized using the oxidation method for green urea production. Hematite nanowires were obtained by the oxidation of an iron wire at a temperature of 650 °C and ambient pressure in the presence of N{sub 2} and O{sub 2} gases. Cupric oxide nanowires were obtained by the same method at 700 °C, using a copper wire. The X-ray diffraction results show the formation of rhombohedral structure of α-Fe{sub 2}O{sub 3} and monoclinic phase of CuO. FE-SEM results reveal the formation of nanowires with dimensions ranging between 5–15 µm and 4–12 µm in length and a diametere ranging between 50–150 nm and 50–250 nm for α-Fe{sub 2}O{sub 3} and CuO respectively. The VSM results show that the saturation magnetization values for hematite and cupric oxide were 132.8700 and 0.0124 emu/g, respectively. The nanowires were used as catalyst for green urea synthesis in the presence of an oscillating and a static magnetic fields. The use of nanocatalyst with high saturation magnetization gives a higher yield of urea due to the increase in the singlet to triplet conversion. The highest yield of urea 11243 ppm was achieved by applying an oscillating magnetic field of frequency 0.5 MHz and using α-Fe{sub 2}O{sub 3} nanowires as nanocatalyst. - Highlights: • Effect of saturation magnetization of nanocatalyst on urea yield was investigated • Using nanocatalyst with high saturation magnetization value improved urea yield. • Effect of oscillating magnetic field frequency on the urea yield was investigated. • The highest urea yield was achieved by applying 0.5 MHz oscillating magnetic field.

  19. The effect of saturation magnetization of nanocatalyst and oscillating magnetic field for green urea synthesis

    International Nuclear Information System (INIS)

    Yahya, Noorhana; Alqasem, Bilal; Irfan, Muhammad; Qureshi, Saima; Rehman, Zia Ur; Shafie, Afza; Soleimani, Hassan

    2017-01-01

    Hematite and cupric oxide nanowires have been synthesized using the oxidation method for green urea production. Hematite nanowires were obtained by the oxidation of an iron wire at a temperature of 650 °C and ambient pressure in the presence of N 2 and O 2 gases. Cupric oxide nanowires were obtained by the same method at 700 °C, using a copper wire. The X-ray diffraction results show the formation of rhombohedral structure of α-Fe 2 O 3 and monoclinic phase of CuO. FE-SEM results reveal the formation of nanowires with dimensions ranging between 5–15 µm and 4–12 µm in length and a diametere ranging between 50–150 nm and 50–250 nm for α-Fe 2 O 3 and CuO respectively. The VSM results show that the saturation magnetization values for hematite and cupric oxide were 132.8700 and 0.0124 emu/g, respectively. The nanowires were used as catalyst for green urea synthesis in the presence of an oscillating and a static magnetic fields. The use of nanocatalyst with high saturation magnetization gives a higher yield of urea due to the increase in the singlet to triplet conversion. The highest yield of urea 11243 ppm was achieved by applying an oscillating magnetic field of frequency 0.5 MHz and using α-Fe 2 O 3 nanowires as nanocatalyst. - Highlights: • Effect of saturation magnetization of nanocatalyst on urea yield was investigated • Using nanocatalyst with high saturation magnetization value improved urea yield. • Effect of oscillating magnetic field frequency on the urea yield was investigated. • The highest urea yield was achieved by applying 0.5 MHz oscillating magnetic field.

  20. Structure and magnetic properties of Alnico ribbons

    Science.gov (United States)

    Zhang, Ce; Li, Ying; Han, Xu-Hao; Du, Shuai-long; Sun, Ji-bing; Zhang, Ying

    2018-04-01

    Al-Ni-Co alloy has been widely applied in various industrial fields due to its excellent thermal and magnetic stability. In this paper, new Al-Ni-Co ribbons are prepared by simple processes combining melt-spinning with annealing, and their phase transition, microstructure and magnetic properties are studied. The results show that after as-spun ribbons are annealed, the grain size of ribbons increases from 1.1 ± 0.3 μm to 4.8 ± 0.8 μm, but still much smaller than that of the bulk Al-Ni-Co alloy manufactured by traditional technologies. In addition, some rod-like Al70Co20Ni10-type, Al9Co2-type and Fe2Nb-type phases are precipitated at grain boundaries; simultaneously, the distinct spinodal decomposition microstructure with periodic ingredient variation is thoroughly formed in all grains by the reaction of α → α1 + α2. Furthermore, the α1 and α2 distribute alternately like a maze, the Fe-Co-rich α1 phase holds 35.9-47.3 vol%, while the Al-Ni-rich α2 phase occupies the rest. Finally, the coercivity of annealed ribbons can reach to 485.3 ± 76.6 Oe. If the annealed ribbons are further aged at 560 °C, their Hc even increases to 738.1 ± 81.0 Oe. The coercivity mechanism is discussed by the combination of microstructure and domain structure.

  1. Ground state magnetic properties of Fe nanoislands on Cu(111)

    International Nuclear Information System (INIS)

    Kishi, Tomoya; David, Melanie; Nakanishi, Hiroshi; Kasai, Hideaki; Dino, Wilson Agerico; Komori, Fumio

    2005-01-01

    We investigate magnetic properties of Fe nanoislands on Cu(111) in the relaxed structure within the density functional theory. We observe that the nanoislands exhibit the ferromagnetic properties with large magnetic moment. We find that the change in the magnetic moment of each Fe atom is induced by deposition on Cu(111) and structure relaxation of Fe nanoislands. Moreover, we examine the stability of ferromagnetic states of Fe nanoislands by performing the total energy calculations. (author)

  2. Synthesis and spectroscopic characterization of magnetic hydroxyapatite nanocomposite using ultrasonic irradiation

    Science.gov (United States)

    Gopi, D.; Ansari, M. Thameem; Shinyjoy, E.; Kavitha, L.

    2012-02-01

    Nowadays magnetic hydroxyapatite (m-HAP) has potential applications in biomedicine more especially for bone cancer treatment. In this paper the functionalization of the hydroxyapatite (HAP) with magnetite nanoparticle (MNP) through ultrasonic irradiation technique is reported and its spectral investigation has been carried out. The ultrasonic irradiation with two different frequencies of 28 kHz and 35 kHz at the power of 150 and 320 W, respectively, was employed for the synthesis of m-HAP. The ultrasound irradiation of 35 kHz at 320 W shows the efficient diffusion of MNP to the HAP host matrix leads to the formation of m-HAP. The ultrasonic irradiation technique does not require stabilizers as in the case of coprecipitation method hence the final product of pure m-HAP is obtained. The X-ray diffraction pattern shows the formation of magnetite nanoparticles which are functionalized with hydroxyapatite host matrix. The vibrating sample magnetometer curve exhibits the super paramagnetic property of the samples and the saturation magnetization ( Ms) value of the functionalized magnetic hydroxyapatite. The Ms value is found to be much less than that of pure magnetite nanoparticle and this decrement in Ms is due to the hindrance of magnetic domain of the particles with HAP. The portrayed Raman spectra discriminate between the m-HAP and MNP with corresponding vibrational modes of frequencies. The transmission electron micrograph shows excellent morphology of functionalized m-HAP in nanometer range. The atomic force microscopic investigation shows the 3-dimensional view of crust and trench shape of m-HAP. All these results confirm the formation of magnetic hydroxyapatite nanocomposite with typical magnetic property for biological applications.

  3. Fabrication and properties of submicrometer structures of magnetic materials

    International Nuclear Information System (INIS)

    Martin, J.I.; Velez, M.; Nogues, J.; Schuller, I.K.

    1998-01-01

    The method of electron beam lithography is described. This technique allows to fabricate well defined submicrometer structures of magnetic materials, that are suitable to show and study interesting physical properties by transport measurements either in Superconductivity or in Magnetism. In particular, using these structures, we have analyzed pinning effects of the vortex lattice in superconductors and magnetization reversal processes in magnetic materials. (Author) 15 refs

  4. The magnetic field dependent dynamic properties of magnetorheological elastomers based on hard magnetic particles

    Science.gov (United States)

    Wen, Qianqian; Wang, Yu; Gong, Xinglong

    2017-07-01

    In this study, novel magnetorheological elastomers based on hard magnetic particles (H-MREs) were developed and the magnetic field dependent dynamic properties of the H-MREs were further investigated. The storage modulus of H-MREs could not only be increased by increasing magnetic field but also be decreased by the increasing magnetic field of opposite orientation. For the anisotropic H-MREs with 80 wt% NdFeB particles, the field-induced increasing and decreasing modulus was 426 kPa and 118 kPa respectively. Moreover, the dynamic performances of H-MREs significantly depended on the pre-structure magnetic field, magnetizing field and test magnetic field. The H-MREs were initially magnetized and formed the chain-like microstructure by the pre-structure magnetic field. The field-induced increasing and decreasing modulus of H-MREs both raised with increasing of the magnetizing field. When the magnetizing field increased from 400 to 1200 kA m-1, the field induced decreasing modulus of the 80 wt% isotropic H-MREs raised from 3 to 47 kPa. The magnetic field dependent curves of H-MREs’ storage modulus were asymmetric if the magnetizing field was higher than the test magnetic field. Based on the dipolar model of MREs and magnetic properties of hard magnetic material, a reasonable explanation was proposed to understand the H-MREs’ field dependent mechanical behaviors.

  5. Mechanochemical synthesis of nanocrystalline Fe and Fe–B magnetic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi, Majid; Ghasemi, Ali, E-mail: ali13912001@yahoo.com; Tavoosi, Majid

    2016-12-01

    Mechanochemical synthesis and magnetic characterization of nanocrystalline Fe and Fe–B magnetic alloys was the goal of this study. In this regard, different Fe{sub 2}O{sub 3}–B{sub 2}O{sub 3} powder mixtures with sufficient amount of CaH{sub 2} were milled in a planetary ball mill in order to produce nanocrystalline Fe, Fe{sub 95}B{sub 5} and Fe{sub 85}B{sub 15} alloys. The produced samples were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The results showed that, nanocrystalline Fe, Fe{sub 95}B{sub 5} and Fe{sub 85}B{sub 15} alloys can be successfully synthesized by the reduction reaction of Fe{sub 2}O{sub 3} and B{sub 2}O{sub 3} with CaH{sub 2} during mechanical alloying. The structure of produced Fe{sub 95}B{sub 5} and Fe{sub 85}B{sub 15} alloys was a combination of Fe and Fe{sub 2}B phases with average crystallite sizes of about 15 and 10 nm, respectively. The produced nanocrystalline alloys exhibited soft magnetic properties with the coercivity and saturation of magnetization in the range of 170–240 Oe and 9–28 emu/g, respectively. Increasing the boron content has a destructive effect on soft magnetic properties of Fe–B alloys. - Highlights: • We study the mechanochemical synthesis of nanocrystalline boron, Fe and Fe–B alloys. • We study the reduction reaction of B{sub 2}O{sub 3}–CaH{sub 2} during milling. • We study the reduction reaction of Fe{sub 2}O{sub 3}–CaH{sub 2} during milling. • We study the reduction reaction of Fe{sub 2}O{sub 3}–B{sub 2}O{sub 3}–CaH{sub 2} during milling. • We study the effect of B on magnetic properties of nanocrystalline Fe–B alloys.

  6. Nanocomposite permanent magnetic materials Nd-Fe-B type: The influence of nanocomposite on magnetic properties

    Directory of Open Access Journals (Sweden)

    Talijan Nadežda M.

    2005-01-01

    Full Text Available The influence on the magnetic properties of nanocristalline ribbons and powders has character of microstructure, between others – the grain size volume of hard and soft magnetic phases and their distribution. Magnetic properties of ribbons and powders depend mainly on their chemical composition and parameters of their heat treatment [1]. Technology of magnets from nanocristalline ribbon consists of the following process: preparing the Nd-Fe- B alloy, preparing the ribbon, powdering of the ribbon, heat treatment of the powder and finally preparing the magnets. Nanocomposite permanent magnet materials based on Nd-Fe- B alloy with Nd low content are a new type of permanent magnetic material. The microstructure of this nanocomposite permanent magnet is composed of a mixture of magnetically soft and hard phases which provide so called exchange coupling effect.

  7. Synthesis of glycinamides using protease immobilized magnetic nanoparticles

    Directory of Open Access Journals (Sweden)

    Abha Sahu

    2016-12-01

    Full Text Available In the present investigation, Bacillus subtilis was isolated from slaughterhouse waste and screened for the production of protease enzyme. The purified protease was successfully immobilized on magnetic nanoparticles (MNPs and used for the synthesis of series of glycinamides. The binding and thermal stability of protease on MNPs was confirmed by FTIR spectroscopy and TGA analysis. The surface morphology of MNPs before and after protease immobilization was carried out using SEM analysis. XRD pattern revealed no phase change in MNPs after enzyme immobilization. The processing parameters for glycinamides synthesis viz. temperature, pH, and time were optimized using Response Surface Methodology (RSM by using Design Expert (9.0.6.2. The maximum yield of various amides 2 butyramidoacetic acid (AMD-1,83.4%, 2-benzamidoacetic acid (AMD-2,80.5% and 2,2′((carboxymethyl amino-2-oxoethyl-2-hydroxysuccinylbis(azanediyldiacetic acid (AMD-3,80.8% formed was observed at pH-8, 50 °C and 30 min. The synthesized immobilized protease retained 70% of the initial activity even after 8 cycles of reuse.

  8. Synthesis of dilute magnetic semiconductors by ion implantation

    International Nuclear Information System (INIS)

    Braunstein, G.H.; Dresselhaus, G.; Withrow, S.P.

    1986-01-01

    We have synthesized layers of CdMnTe by implantation of Mn into CdTe. Samples of CdTe have been implanted with Mn ions of 60 keV energy to fluences in the range 1 x 10 13 cm -2 to 2 x 10 16 cm -2 resulting in local concentrations of up to 10% at the maximum of the Mn distribution. Rutherford backscattering-channeling analysis has been used to study the radiation damage after implantation and after subsequent rapid thermal annealing (RTA). These experiments reveal that RTA for 15 sec at a temperature T greater than or equal to 700 0 C results in the complete recovery of the lattice order, without affecting the stoichiometry of CdTe. Photoluminescence (PL) measurements of a sample showing complete annealing reveal an increase in the band gap corresponding to the synthesis of very dilute (x approx. = 0.004) Cd/sub 1-x/Mn/sub x/Te. A shift of the excitonic PL peak to lower energies is observed when a magnetic field H less than or equal to 1T is applied. These measurements provide clear evidence for the synthesis of a DMS by ion implantation of Mn into CdTe

  9. Physical property control in core/shell inorganic nanostructures for fluorescence and magnetic targeting applications

    Science.gov (United States)

    Roberts, Stephen K.

    Nanomaterials show immense promise for the future in numerous areas of application. Properties that are unique from the bulk material and are tunable allow for innovation in material design. This thesis will focus on controlling the physical properties of core/shell nanostructures to enhance the utility of the materials. The first focus is on the impact of different solvent mixtures during the shell growth phase of SILAR based core/shell quantum dot synthesis is studied. Gaining insight into the mechanism for SILAR growth of core/shell nanoparticles allows improved synthetic yields and precursor binding, providing enhanced control to synthesis of core/shell nanoparticles. The second focus of this thesis is exploring the use of magnetic nanoparticles for magnetic drug targeting for cardiovascular conditions. Magnetic targeting for drug delivery enables increased local drug concentration, while minimizing non-specific interactions. In order to be effective for magnetic targeting, it must be shown that low magnetic strength is sufficient to capture flowing nanoparticles. By demonstrating the binding of a therapeutic agent to the surface at medicinal levels, the viability for use as a nanoparticle drug delivery system is improved.

  10. Dynamic rheological properties of viscoelastic magnetic fluids in uniform magnetic fields

    International Nuclear Information System (INIS)

    Yamaguchi, Hiroshi; Niu Xiaodong; Ye Xiaojiang; Li Mingjun; Iwamoto, Yuhiro

    2012-01-01

    The dynamic rheological properties of viscoelastic magnetic fluids in externally applied uniform magnetic fields are investigated by a laboratory-made cone-plate rheometer in this study. In particular, the effects of the magnetic field on the viscoelastic properties (the complex dynamic modulus) of the viscoelastic magnetic fluids are studied. In the investigation, three viscoelastic magnetic fluids are made by mixing a magnetic fluid and a viscoelastic fluid with different mass ratios. As a supplementation to the experimental investigation, a theoretical analysis is also presented. The present study shows that the viscosity and elasticity of the viscoelastic magnetic fluids are significantly influenced by the magnetic field and the concentrations of the magnetic particles in the test fluids. Theoretical analysis qualitatively explains the present findings. - Highlights: ► The dynamic rheological properties of the viscoelastic magnetic fluids in uniform magnetic fields are investigated. ► Both the magnetic field strength and the concentration of the magnetic particles in the fluids have significant effects on the viscosity and elasticity of the viscoelastic magnetic fluids. ► Theoretical prediction and analysis qualitatively explains the present findings.

  11. In situ synthesis of magnetic CaraPVA IPN nanocomposite hydrogels and controlled drug release

    International Nuclear Information System (INIS)

    Mahdavinia, Gholam Reza; Etemadi, Hossein

    2014-01-01

    In this work, the magnetic nanocomposite hydrogels that focused on targeted drug delivery were synthesized by incorporation of polyvinyl alcohol (PVA), kappa-carrageenan (Cara), and magnetite Fe 3 O 4 nanoparticles. The magnetic nanoparticles were obtained in situ in the presence of a mixture of polyvinyl alcohol/kappa-carrageenan (CaraPVA). The produced magnetite-polymers were cross-linked with freezing–thawing technique and subsequent with K + solution. The synthesized hydrogels were thoroughly characterized by transmittance electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and vibrating sample magnetometer (VSM) techniques. The dynamic swelling kinetic models of hydrogels were analyzed according to the first- and second-order kinetic models and were found that the experimental kinetics data followed the second-order model well. Drug loading and release efficiency were evaluated by diclofenac sodium (DS) as the model drug. The in vitro drug release studies from hydrogels exhibited significant behaviors on the subject of physiological simulated pHs and external magnetic fields. Investigation on the antibacterial activity revealed the ability of drug-loaded hydrogels to inactivate the Gram-positive Staphylococcus aureus (S. aureus) bacteria. The mucoadhesive properties of the hydrogels were studied and the hydrogels containing kappa-carrageenan showed good mucoadhesiveness in both simulated gastric and intestinal conditions. - Highlights: • In situ synthesis of magnetic kappa-carrageenan/PVA nanocomposite hydrogel. • Low salt sensitivity of magnetic nanocomposite hydrogels was observed. • The release of diclofenac sodium from hydrogels was pH-dependent. • The release of diclofenac sodium from magnetic hydrogels was affected by external magnetic field. • The hydrogels containing carrageenan component showed high mucoadhesiveness

  12. In situ synthesis of magnetic CaraPVA IPN nanocomposite hydrogels and controlled drug release

    Energy Technology Data Exchange (ETDEWEB)

    Mahdavinia, Gholam Reza, E-mail: grmnia@maragheh.ac.ir; Etemadi, Hossein

    2014-12-01

    In this work, the magnetic nanocomposite hydrogels that focused on targeted drug delivery were synthesized by incorporation of polyvinyl alcohol (PVA), kappa-carrageenan (Cara), and magnetite Fe{sub 3}O{sub 4} nanoparticles. The magnetic nanoparticles were obtained in situ in the presence of a mixture of polyvinyl alcohol/kappa-carrageenan (CaraPVA). The produced magnetite-polymers were cross-linked with freezing–thawing technique and subsequent with K{sup +} solution. The synthesized hydrogels were thoroughly characterized by transmittance electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and vibrating sample magnetometer (VSM) techniques. The dynamic swelling kinetic models of hydrogels were analyzed according to the first- and second-order kinetic models and were found that the experimental kinetics data followed the second-order model well. Drug loading and release efficiency were evaluated by diclofenac sodium (DS) as the model drug. The in vitro drug release studies from hydrogels exhibited significant behaviors on the subject of physiological simulated pHs and external magnetic fields. Investigation on the antibacterial activity revealed the ability of drug-loaded hydrogels to inactivate the Gram-positive Staphylococcus aureus (S. aureus) bacteria. The mucoadhesive properties of the hydrogels were studied and the hydrogels containing kappa-carrageenan showed good mucoadhesiveness in both simulated gastric and intestinal conditions. - Highlights: • In situ synthesis of magnetic kappa-carrageenan/PVA nanocomposite hydrogel. • Low salt sensitivity of magnetic nanocomposite hydrogels was observed. • The release of diclofenac sodium from hydrogels was pH-dependent. • The release of diclofenac sodium from magnetic hydrogels was affected by external magnetic field. • The hydrogels containing carrageenan component showed high

  13. Magnetic and Electric Properties of , ( Layered Perovskites

    Directory of Open Access Journals (Sweden)

    A. I. Ali

    2013-01-01

    Full Text Available The electric and magnetic properties of layered perovskites have been investigated systematically over the doping range . It was found that both Sr1.5Y0.5CoO4 and Sr1.4Y0.6CoO4 undergo ferromagnetic (FM transition around 145 K and 120 K, respectively. On the other hand, Sr1.3Y0.7CoO4 and Sr1.2Y0.8CoO4 compounds showed paramagnetic behavior over a wide range of temperatures. In addition, spin-glass transition ( was observed at 10 K for Sr1.3Y0.7CoO4. All investigated samples are semiconducting-like within the temperature range of 10–300 K. The temperature dependence of the electrical resistivity, , was described by two-dimensional variable range hopping (2D-VRH model at 50 K < ≤ 300 K. Comparison with other layered perovskites was discussed in this work.

  14. Size-dependent magnetic properties of iron oxide nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Patsula, Vitalii; Moskvin, Maksym; Dutz, S.; Horák, Daniel

    2016-01-01

    Roč. 88, January (2016), s. 24-30 ISSN 0022-3697 R&D Projects: GA MŠk(CZ) LH14318 Institutional support: RVO:61389013 Keywords : magnetic materials * chemical synthesis * infrared spectroscopy Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.059, year: 2016

  15. Rational synthesis of zerovalent iron/bamboo charcoal composites with high saturation magnetization

    Science.gov (United States)

    Mingshan Wu; Jianfeng Ma; Zhiyong Cai; Genlin Tian; Shumin Yang; Youhong Wang; Xing' e Liu

    2015-01-01

    The synthesis of magnetic biochar composites is a major new research area in advanced materials sciences. A series of magnetic bamboo charcoal composites (MBC800, MBC1000 and MBC1200) with high saturation magnetization (Ms) was fabricated in this work by mixing bamboo charcoal powder with an aqueous ferric chloride solution and subsequently...

  16. Inorganic anion-dependent assembly of zero-, one-, two- and three-dimensional Cu(II)/Ag(I) complexes under the guidance of the HSAB theory: Synthesis, structure, and magnetic property

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yaru; Xing, Zhiyan [School of Science, North University of China, Taiyuan, Shanxi 030051 (China); Zhang, Xiao [MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150080 (China); Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080 PR China (China); Liang, Guorui [School of Science, North University of China, Taiyuan, Shanxi 030051 (China)

    2017-02-15

    To systematically explore the influence of inorganic anions on building coordination complexes, five novel complexes based on 1-(benzotriazole-1-methyl)−2-propylimidazole (bpmi), [Cu(bpmi){sub 2}(Ac){sub 2}]·H{sub 2}O (1), [Cu(bpmi){sub 2}(H{sub 2}O){sub 2}]·2NO{sub 3}·2H{sub 2}O (2), [Cu(bpmi)(N{sub 3}){sub 2}] (3), [Ag(bpmi)(NO{sub 3})] (4) and [Cu{sub 3}(bpmi){sub 2}(SCN){sub 4}(DMF)] (5) (Ac{sup −}=CH{sub 3}COO{sup −}, DMF=N,N-Dimethylformamide) are synthesized through rationally introducing Cu(II) salts and Ag(I) salt with different inorganic anions. X-ray single-crystal analyses reveal that these complexes show interesting structural features from mononuclear (1), one-dimensional (2 and 3), two-dimensional (4) to three-dimensional (5) under the influence of inorganic anions with different basicities. The structural variation can be explained by the hard-soft-acid-base (HSAB) theory. Magnetic susceptibility measurement indicates that complex 3 exhibits an antiferromagnetic coupling between adjacent Cu(II) ions. - Graphical abstract: Five new Cu(II)/Ag(I) complexes show interesting structural features from mononuclear, one-dimension, two-dimension to three-dimension under the influence of inorganic anions. The structural variation can be explained by the HSAB theory. - Highlights: • Five inorganic anion-dependent complexes are synthesized. • Structural variation can be explained by the hard-soft-acid-base (HSAB) theory. • The magnetic property of complex has been studied.

  17. Synthesis and properties of porous zeolite aluminosilicate adsorbents

    International Nuclear Information System (INIS)

    Shilina, A.S.; Milinchuk, V.K.; Burukhin, S.B.; Gordienko, A.B.

    2015-01-01

    Environmentally safe non-energy-intensive methods of the synthesis have been developed and the properties of solid inorganic nanostructured zeolite-like adsorbents of a broad spectrum have been studied. The sorption capacities of the adsorbents with respect to various components of water pollution have been determined [ru

  18. Molecular clips based on propanediurea : synthesis and physical properties

    NARCIS (Netherlands)

    Jansen, Robertus Johannes

    2002-01-01

    This thesis describes the synthesis and physical properties of a series of molecular clips derived from the concave molecule propanediurea. These molecular clips are cavity-containing receptors that can bind a variety of aromatic guests. This binding is a result of hydrogen bonding and pi-pi

  19. Synthesis and properties of heterocyclic type I photoinitiators

    International Nuclear Information System (INIS)

    Liska, R.; Knaus, S.; Wendrinsky, J.

    1999-01-01

    The synthesis and properties of a series of new heterocyclic hydroxyalkylphenone-analogous photoinitiators (PIs) is described. The PIs are obtained by reaction of aromatic organolithium compounds with nitriles or by Friedel-Craft's-acylation. Preliminary photocalorimetric tests and UV absorption data are included

  20. Synthesis, structural and optical properties of nanoparticles (Al, V ...

    Indian Academy of Sciences (India)

    The synthesis by the sol–gel method, structural and optical properties of ZnO, Zn0.99Al0.01O (AlZ),. Zn0.9V0.1O (VZ) ... drops of the resulting suspension containing the synthesized .... ZnO films on silicon substrate, they thought that this emis-.

  1. Synthesis, characterization and emission properties of quinolin-8 ...

    Indian Academy of Sciences (India)

    Unknown

    chelated ruthenium organometallics. BIKASH KUMAR PANDA. Department of Inorganic ... Ruthenium organometallics; quinolin-8-olato chelation; emission properties; trivalent ruthenium. 1. Introduction. There is continuing ... chem.istry of orthometallated ruthenium compounds is of current interest in the context of synthesis ...

  2. Transition metal borides. Synthesis, characterization and superconducting properties

    Energy Technology Data Exchange (ETDEWEB)

    Kayhan, Mehmet

    2013-07-12

    A systematic study was done on the synthesis and superconducting properties of metal rich transition metal borides. Five different binary systems were investigated including the boride systems of niobium, tantalum, molybdenum, tungsten and rhenium. High temperature solid state methods were used in order to synthesize samples of different transition metal borides of the composition M{sub 2}B, MB, M{sub 3}B{sub 2}, MB{sub 2}, and M{sub 2}B{sub 4}. The reactions were carried out in three different furnaces with different sample containers: the electric arc (copper crucible), the high frequency induction furnace (boron nitride, tantalum or glassy carbon crucibles), and the conventional tube furnace (sealed evacuated quartz ampoules). The products obtained were characterized with X-ray powder diffractometry, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Phase analyses and crystal structure refinements using the Rietveld method and based on structure models known from literature were performed. A neutron diffraction measurement was done for W{sub 2}B{sub 4} to allow for a complete crystal structure determination, because of the presence of a heavy element like tungsten and a light element like boron that made it difficult to determine the accurate determination of the boron atom positions and occupancies from X-ray data. A new structure model for W{sub 2}B{sub 4} was proposed. Magnetic measurements in a SQUID magnetometer down to temperatures as low as 1.8 K were performed to several of the products in order to see if the transition metal borides become superconducting at low temperatures, and the results were compared with data from literature. Superconducting properties were found for the following compounds: NbB{sub 2} (T{sub C} = 3.5 K), β-MoB (T{sub C} = 2.4 K), β-WB (T{sub C} = 2.0 K), α-WB (T{sub C} = 4.3 K), W{sub 2}B{sub 4} (T{sub C} = 5.4 K), Re{sub 7}B{sub 3} (T{sub C} = 2.4 K). A relationship between the superconducting properties

  3. Transition metal borides. Synthesis, characterization and superconducting properties

    International Nuclear Information System (INIS)

    Kayhan, Mehmet

    2013-01-01

    A systematic study was done on the synthesis and superconducting properties of metal rich transition metal borides. Five different binary systems were investigated including the boride systems of niobium, tantalum, molybdenum, tungsten and rhenium. High temperature solid state methods were used in order to synthesize samples of different transition metal borides of the composition M 2 B, MB, M 3 B 2 , MB 2 , and M 2 B 4 . The reactions were carried out in three different furnaces with different sample containers: the electric arc (copper crucible), the high frequency induction furnace (boron nitride, tantalum or glassy carbon crucibles), and the conventional tube furnace (sealed evacuated quartz ampoules). The products obtained were characterized with X-ray powder diffractometry, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Phase analyses and crystal structure refinements using the Rietveld method and based on structure models known from literature were performed. A neutron diffraction measurement was done for W 2 B 4 to allow for a complete crystal structure determination, because of the presence of a heavy element like tungsten and a light element like boron that made it difficult to determine the accurate determination of the boron atom positions and occupancies from X-ray data. A new structure model for W 2 B 4 was proposed. Magnetic measurements in a SQUID magnetometer down to temperatures as low as 1.8 K were performed to several of the products in order to see if the transition metal borides become superconducting at low temperatures, and the results were compared with data from literature. Superconducting properties were found for the following compounds: NbB 2 (T C = 3.5 K), β-MoB (T C = 2.4 K), β-WB (T C = 2.0 K), α-WB (T C = 4.3 K), W 2 B 4 (T C = 5.4 K), Re 7 B 3 (T C = 2.4 K). A relationship between the superconducting properties and the compositional and structural features was discussed for metal diborides. Also it was

  4. Magnetic properties of multiferroic TbMnO{sub 3} doped with Al

    Energy Technology Data Exchange (ETDEWEB)

    Perez, F. [Centro de Ciencias de la Materia Condensada, Universidad Nacional Autonoma de Mexico, Km. 107.5 Carretera Tijuana-Ensenada, Ensenada, B.C. (Mexico); Escudero, R. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, A. Postal 70-360, Mexico, D.F. 04510 (Mexico); Heiras, J.

    2007-07-01

    The synthesis, characterization, and magnetic properties of polycrystalline Tb{sub 1-x}Al{sub x}MnO{sub 3} with x=0.05 and 0.1 is reported. Samples were synthesized by the conventional solid state reaction method producing single phase compounds. Rietveld refinements indicate that Al substitutes Tb in the structure. Samples were highly porous with grain sizes up to {proportional_to}10 {mu}m. The magnetic measurements show a magnetic ordering, starting from antiferromagnetism, for the undoped sample, to a weak ferromagnetic phase coexisting with the antiferromagnetic phase for the two x values. The magnetic ordering is attributed to two different contributions of Mn and Tb sublattices. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. In-situ synthesis of magnetic iron-oxide nanoparticle-nanofibre composites using electrospinning

    International Nuclear Information System (INIS)

    Burke, Luke; Mortimer, Chris J.; Curtis, Daniel J.; Lewis, Aled R.; Williams, Rhodri; Hawkins, Karl; Maffeis, Thierry G.G.; Wright, Chris J.

    2017-01-01

    We demonstrate a facile, one-step process to form polymer scaffolds composed of magnetic iron oxide nanoparticles (MNPs) contained within electrospun nano- and micro-fibres of two biocompatible polymers, Poly(ethylene oxide) (PEO) and Poly(vinyl pyrrolidone) (PVP). This was achieved with both needle and free-surface electrospinning systems demonstrating the scalability of the composite fibre manufacture; a 228 fold increase in fibre fabrication was observed for the free-surface system. In all cases the nanoparticle-nanofibre composite scaffolds displayed morphological properties as good as or better than those previously described and fabricated using complex multi-stage techniques. Fibres produced had an average diameter (Needle-spun: 125 ± 18 nm (PEO) and 1.58 ± 0.28 μm (PVP); Free-surface electrospun: 155 ± 31 nm (PEO)) similar to that reported previously, were smooth with no bead defects. Nanoparticle-nanofibre composites were characterised using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS) (Nanoparticle average diameter ranging from 8 ± 3 nm to 27 ± 5 nm), XRD (Phase of iron oxide nanoparticles identified as magnetite) and nuclear magnetic resonance relaxation measurements (NMR) (T1/T2: 32.44 for PEO fibres containing MNPs) were used to verify the magnetic behaviour of MNPs. This study represents a significant step forward for production rates of magnetic nanoparticle-nanofibre composite scaffolds by the electrospinning technique. - Graphical abstract: We present a novel facile, one-step process for the in-situ synthesis of magnetic iron oxide nanoparticle-nanofibre composites using both needle and free-surface electrospinning. This is a significant step forward for production rates of magnetic nanoparticle-nanofibre scaffolds both in terms of fibre and nanoparticle production. - Highlights: • We present a novel process for the in-situ synthesis of magnetic iron oxide nanoparticle

  6. In-situ synthesis of magnetic iron-oxide nanoparticle-nanofibre composites using electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Burke, Luke; Mortimer, Chris J. [Biomaterials, Biofouling and Biofilms Engineering Laboratory (B3EL), Systems and Process Engineering Centre, College of Engineering, Swansea University, Fabian Way, Swansea SA1 8EN (United Kingdom); Systems and Process Engineering Centre, College of Engineering, Swansea University, Fabian Way, Swansea SA1 8EN (United Kingdom); Curtis, Daniel J.; Lewis, Aled R.; Williams, Rhodri [Systems and Process Engineering Centre, College of Engineering, Swansea University, Fabian Way, Swansea SA1 8EN (United Kingdom); Hawkins, Karl [Centre for NanoHealth (CNH), Swansea University, Singleton Park, Swansea SA2 8PP (United Kingdom); Maffeis, Thierry G.G. [Systems and Process Engineering Centre, College of Engineering, Swansea University, Fabian Way, Swansea SA1 8EN (United Kingdom); Wright, Chris J., E-mail: c.wright@swansea.ac.uk [Biomaterials, Biofouling and Biofilms Engineering Laboratory (B3EL), Systems and Process Engineering Centre, College of Engineering, Swansea University, Fabian Way, Swansea SA1 8EN (United Kingdom); Systems and Process Engineering Centre, College of Engineering, Swansea University, Fabian Way, Swansea SA1 8EN (United Kingdom); Centre for NanoHealth (CNH), Swansea University, Singleton Park, Swansea SA2 8PP (United Kingdom)

    2017-01-01

    We demonstrate a facile, one-step process to form polymer scaffolds composed of magnetic iron oxide nanoparticles (MNPs) contained within electrospun nano- and micro-fibres of two biocompatible polymers, Poly(ethylene oxide) (PEO) and Poly(vinyl pyrrolidone) (PVP). This was achieved with both needle and free-surface electrospinning systems demonstrating the scalability of the composite fibre manufacture; a 228 fold increase in fibre fabrication was observed for the free-surface system. In all cases the nanoparticle-nanofibre composite scaffolds displayed morphological properties as good as or better than those previously described and fabricated using complex multi-stage techniques. Fibres produced had an average diameter (Needle-spun: 125 ± 18 nm (PEO) and 1.58 ± 0.28 μm (PVP); Free-surface electrospun: 155 ± 31 nm (PEO)) similar to that reported previously, were smooth with no bead defects. Nanoparticle-nanofibre composites were characterised using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS) (Nanoparticle average diameter ranging from 8 ± 3 nm to 27 ± 5 nm), XRD (Phase of iron oxide nanoparticles identified as magnetite) and nuclear magnetic resonance relaxation measurements (NMR) (T1/T2: 32.44 for PEO fibres containing MNPs) were used to verify the magnetic behaviour of MNPs. This study represents a significant step forward for production rates of magnetic nanoparticle-nanofibre composite scaffolds by the electrospinning technique. - Graphical abstract: We present a novel facile, one-step process for the in-situ synthesis of magnetic iron oxide nanoparticle-nanofibre composites using both needle and free-surface electrospinning. This is a significant step forward for production rates of magnetic nanoparticle-nanofibre scaffolds both in terms of fibre and nanoparticle production. - Highlights: • We present a novel process for the in-situ synthesis of magnetic iron oxide nanoparticle

  7. Synthesis, characterization and photoluminescence properties of ...

    Indian Academy of Sciences (India)

    Further, TEM image of azo-GO indicates some dark spots on the GO sheets due to azo functionalization. AFM ... Introduction. Photochromic compounds, which can easily undergo ... change in optical properties and morphologies.9,10.

  8. Synthesis, microstructure and mechanical properties of ceria ...

    Indian Academy of Sciences (India)

    Unknown

    ceria stabilized zirconia powders with improved mechanical properties. Ce–ZrO2 with 20 wt% ... structural ceramic materials (Garvie et al 1975; Evans and. Cannon 1986) ... thermal expansion matching with that of iron alloys. (Tsukuma and ...

  9. Photothermal investigation of local and depth dependent magnetic properties

    International Nuclear Information System (INIS)

    Pelzl, J; Meckenstock, R

    2010-01-01

    To achieve a spatially resolved measurement of magnetic properties two different photothermal approaches are used which rely on heat dissipated by magnetic resonance absorption or thermal modulation of the magnetic properties, respectively. The heat produced by modulated microwave absorption is detected by the classical photothermal methods such as photoacoustic effect and mirage effect. Examples comprise depth resolution of the magnetization of layered tapes and visualisation of magnetic excitations in ferrites. The second photothermal technique relies on the local modulation of magnetic properties by a thermal wave generated with an intensity modulated laser beam incident on the sample. This technique has a higher spatial resolution and sensitivity and has been used to characterize lateral magnetic properties of multilayers and spintronic media. To extend the lateral resolution of the ferromagnetic resonance detection into the nm-range techniques have been developed which are based on the detection of the modulated thermal microwave response by the thermal probe of an atomic force microscope (AFM) or by detection the thermal expansion of the magnetic sample in the course of the resonant microwave absorption with an AFM or tunnelling microscope. These thermal near field based techniques in ferromagnetic resonance have been successfully applied to image magnetic inhomogeneities around nano-structures and to measure the ferromagnetic resonance from magnetic nano-dots.

  10. Effect of magnetic field on the physical properties of water

    Science.gov (United States)

    Wang, Youkai; Wei, Huinan; Li, Zhuangwen

    2018-03-01

    In this study, the effect of magnetic field (MF) on the partial physical properties of water are reported, tap water (TW) and 4 types of magnetized water (MW) were measured in the same condition. It was found that the properties of TW were changed following the MF treatment, shown as the increase of evaporation amount, the decrease of specific heat and boiling point after magnetization, the changes depend on the magnetization effect. In addition, magnetic field strength (MFS) has a marked influence on the magnetization effect, the optimal magnetizing condition was determined as the MFS of 300 mT. The findings of this study offered a facile approach to improve cooling and power generation efficiency in industrial.

  11. Optimization of Iron Oxide Tracer Synthesis for Magnetic Particle Imaging

    Directory of Open Access Journals (Sweden)

    Sabina Ziemian

    2018-03-01

    Full Text Available The optimization of iron oxide nanoparticles as tracers for magnetic particle imaging (MPI alongside the development of data acquisition equipment and image reconstruction techniques is crucial for the required improvements in image resolution and sensitivity of MPI scanners. We present a large-scale water-based synthesis of multicore superparamagnetic iron oxide nanoparticles stabilized with dextran (MC-SPIONs. We also demonstrate the preparation of single core superparamagnetic iron oxide nanoparticles in organic media, subsequently coated with a poly(ethylene glycol gallic acid polymer and phase transferred to water (SC-SPIONs. Our aim was to obtain long-term stable particles in aqueous media with high MPI performance. We found that the amplitude of the third harmonic measured by magnetic particle spectroscopy (MPS at 10 mT is 2.3- and 5.8-fold higher than Resovist for the MC-SPIONs and SC-SPIONs, respectively, revealing excellent MPI potential as compared to other reported MPI tracer particle preparations. We show that the reconstructed MPI images of phantoms using optimized multicore and specifically single-core particles are superior to that of commercially available Resovist, which we utilize as a reference standard, as predicted by MPS.

  12. Nucleon magnetic moments and magnetic properties of vacuum in QCD

    International Nuclear Information System (INIS)

    Ioffe, B.L.; Smilga, A.V.

    1983-01-01

    Magnetic moments of a proton and a neutron are calculated in the QCD sum rule approach. The substantial role of the external electromagnetic field induced vacuum expectation values, the most important of which is connected with quark condensate magnetic susceptibility, is demonstrated. The results are μsub(p)=3.0, μsub(n)=2.0(+-10%) that is in a perfect agreement with experiment. The invariant amplitudes of Δ→pγ transition are also calculated

  13. Phase composition and magnetic properties in nanocrystalline permanent magnets based on misch-metal

    Science.gov (United States)

    Ma, Q.; Wang, J.; Zhang, Z. Y.; Zhang, X. F.; Liu, F.; Liu, Y. L.; Jv, X. M.; Li, Y. F.; Wang, G. F.

    2017-09-01

    The magnetic properties and phase composition of magnets based on misch-metal (MM) with nominal composition of MM13+xFe84-xB6.5 with x = 0.5, 1, 1.5, 2 and 2.5 using melt-spinning method were investigated. For x = 1.5, it could exhibit best magnetic properties (Hcj = 753.02 kA m-1, (BH)max = 70.77 kJ m-3). X-ray diffraction and energy dispersive spectroscopy show that the multi hard magnetic phase of RE2Fe14B (RE = La, Ce, Pr, Nd) existed in the magnets. The domain wall pinning effect and the exchange coupling interaction between grains are dependent on the abnormal RE-rich phase composition. Optimizing the phase constitution is necessary to improve magnetic properties in MM-Fe-B magnets for utilizing the rare earth resource in a balanced manner.

  14. Process and magnetic properties of cold pressed Ne Fe B bonded magnets

    International Nuclear Information System (INIS)

    Rodrigues, DAniel; Concilio, Gilberto Vicente; Landgraf, Fernando Jose Gomes; Zanchetta, Antonio Carlos

    1996-01-01

    Bonded magnets are polymer composites based on a mixture of a hard magnetic powder and a polymer. This mixture is processed as a traditional powder metallurgy material, cold pressed, or like a thermoplastic material, by injection molding. The polymeric phase to a large extent determines the mechanical properties of the composite, while magnetic powder determines its magnetic properties. They are less expensive and easier to produce, specially in the case of high complexity parts. This paper presents the relationship between process variables and magnetic properties of cold pressed Nd Fe B bonded magnets produced from melt spun flakes mixed with thermosetting resins. The experiments were done using Statistical Design of Experiments. The variables investigates were: uniaxial compaction pressure, binder type; binder content; size of Nd Fe B particles; addition of lubricant; and addition of small quantities of magnetic additives, particles of ferrites, iron, or alnico. (author)

  15. Magnetic properties of a doped graphene-like bilayer

    Energy Technology Data Exchange (ETDEWEB)

    Guo, An-Bang [School of Science, Shenyang University of Technology, Shenyang 110870 (China); Jiang, Wei, E-mail: weijiang.sut.edu@gmail.com [School of Science, Shenyang University of Technology, Shenyang 110870 (China); Zhang, Na [Shenyang Normal University, Shenyang 110034 (China)

    2017-05-15

    A doped graphene-like bilayer is described using a four-sublattice Heisenberg model both ferromagnetic and antiferrimagnetic couplings. The magnetic properties of the bilayer system are studied using the Heisenberg model, retarded Green's function and the linear spin-wave approximation. The spin-wave spectra, energy gap, and the magnetization and quantum fluctuation of the system at the ground state are calculated with various intra- and interlayer couplings. The results indicate that the effect of antiferromagnetic exchange coupling on the magnetic properties of the system is significant. Magnetizations at low temperature show intersection points due to the quantum effects.

  16. New materials graphyne, graphdiyne, graphone, and graphane: review of properties, synthesis, and application in nanotechnology