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Sample records for reduced-dimensional magnetic materials

  1. Science and technology of reduced-dimensional magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Heffner, R.H.; Bishop, A.R.; Hundley, M.F.; Jia, Q.; Neumeier, J.J.; Trugman, S.A.; Thompson, J.D.; Wu, X.D.; Zhang, J.

    1998-12-31

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). This work involved the synthesis of single crystal and thin film samples of magnetoresistive manganites (LaMnO{sub 3} doped with Ca and Sr) and the characterization of their electronic transport properties to understand the underlying physical mechanisms responsible for the colossal magnetoresistance (CMR) of these materials. The experimental program was supplemented by a modeling effort that sought to develop microscopic mathematical models of the observed phenomena. The authors succeeded in finding an important relation between the magnetization and resistivity in these materials, which helps to explain the importance of lattice distortions accompanied by clusters of ferromagnetic spins (called spin-lattice polarons) in the CMR phenomena. In addition, they developed rudimentary tunnel junctions of CMR-insulator-CMR multilayers that will lead to possible applications of these materials as magnetic sensors.

  2. Correlation effects driven by reduced dimensionality in magnetic ...

    Indian Academy of Sciences (India)

    2015-06-02

    Jun 2, 2015 ... Enhanced correlations resulting from the reduced dimensionality of the surface alloys lead to the modification of the core level and valence band electronic structures resulting in the appearance of distinct satellite features. Apart from this, surface alloying-induced strong modifications in the substrate surface ...

  3. Revealing Optical Properties of Reduced-Dimensionality Materials at Relevant Length Scales.

    Science.gov (United States)

    Ogletree, D Frank; Schuck, P James; Weber-Bargioni, Alexander F; Borys, Nicholas J; Aloni, Shaul; Bao, Wei; Barja, Sara; Lee, Jiye; Melli, Mauro; Munechika, Keiko; Whitelam, Stephan; Wickenburg, Sebastian

    2015-10-14

    Reduced-dimensionality materials for photonic and optoelectronic applications including energy conversion, solid-state lighting, sensing, and information technology are undergoing rapid development. The search for novel materials based on reduced-dimensionality is driven by new physics. Understanding and optimizing material properties requires characterization at the relevant length scale, which is often below the diffraction limit. Three important material systems are chosen for review here, all of which are under investigation at the Molecular Foundry, to illustrate the current state of the art in nanoscale optical characterization: 2D semiconducting transition metal dichalcogenides; 1D semiconducting nanowires; and energy-transfer in assemblies of 0D semiconducting nanocrystals. For each system, the key optical properties, the principal experimental techniques, and important recent results are discussed. Applications and new developments in near-field optical microscopy and spectroscopy, scanning probe microscopy, and cathodoluminescence in the electron microscope are given detailed attention. Work done at the Molecular Foundry is placed in context within the fields under review. A discussion of emerging opportunities and directions for the future closes the review. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Magnetic Materials

    Science.gov (United States)

    1985-03-01

    L -:• •.1 S..+.: s• S,’S .+m • , ++ d ’N .,.++.+ ii L+ i+- -..’ *4’.. ’-t. COMM4ITTEE ON MAGNETIC MATERIALS Chairman ROBERT M. WRITE, Principal...Motors; Sung Ho Jin, AT&T Bell Labs; G. Rodrigue, ... -- =.• Georgia Tech; J. Houze , Allegheny-Ludlum; R. Sundahl, AT&T Bell Labs; (. I... R. O’Handley...this report. Robert M. White Chairman *’-’ . ,i-.. .- ABSTRACT Magnetic materials play a fundamental role in many of the electrical and electronic

  5. Novel functional magnetic materials fundamentals and applications

    CERN Document Server

    2016-01-01

    This book presents current research on advanced magnetic materials and multifunctional composites. Recent advances in technology and engineering have resulted from the development of advanced magnetic materials with improved functional magnetic and magneto-transport properties. Certain industrial sectors, such as magnetic sensors, microelectronics, and security, demand cost-effective materials with reduced dimensionality and desirable magnetic properties such as enhanced magnetic softness, giant magnetic field sensitivity, and large magnetocaloric effect.  Expert chapters present the most up-to-date information on the fabrication process, processing, tailoring of properties, and applications of different families of modern functional materials for advanced smart applications. Topics covered include novel magnetic materials and applications; amorphous and nanocrystalline magnetic materials and applications; hard magnetic materials; magnetic shape memory alloys; and magnetic oxides. The book's highly interdis...

  6. Magnetism Materials and Applications

    CERN Document Server

    Trémolet de Lacheisserie, Étienne; Schlenker, Michel

    2005-01-01

    This book treats permanent magnet (hard) materials, magnetically soft materials for low-frequency applications and for high-frequency electronics, magnetostrictive materials, superconductors, magnetic-thin films and multilayers, and ferrofluids. Chapters are dedicated to magnetic recording, the role of magnetism in magnetic resonance imaging (MRI), and instrumentation for magnetic measurements.   

  7. Frontiers in Magnetic Materials

    CERN Document Server

    Narlikar, Anant V

    2005-01-01

    Frontiers in Magnetic Materials focuses on the current achievements and state-of-the-art advancements in magnetic materials. Several lines of development- High-Tc Superconductivity, Nanotechnology and refined experimental techniques among them – raised knowledge and interest in magnetic materials remarkably. The book comprises 24 chapters on the most relevant topics written by renowned international experts in the field. It is of central interest to researchers and specialists in Physics and Materials Science, both in academic and industrial research, as well as advanced students.

  8. Handbook of Advanced Magnetic Materials

    CERN Document Server

    Liu, Yi; Shindo, Daisuke

    2006-01-01

    From high-capacity, inexpensive hard drives to mag-lev trains, recent achievements in magnetic materials research have made the dreams of a few decades ago reality. The objective of Handbook of Advanced Magnetic Materials is to provide a timely, comprehensive review of recent progress in magnetic materials research. This broad yet detailed reference consists of four volumes: 1.) Nanostructured advanced magnetic materials, 2.) Characterization and simulation of advanced magnetic materials, 3.) Processing of advanced magnetic materials, and 4.) Properties and applications of advanced magnetic materials The first volume documents and explains recent development of nanostructured magnetic materials, emphasizing size effects. The second volume provides a comprehensive review of both experimental methods and simulation techniques for the characterization of magnetic materials. The third volume comprehensively reviews recent developments in the processing and manufacturing of advanced magnetic materials. With the co...

  9. Materials for superconducting magnets

    Science.gov (United States)

    Komarek, P.

    1988-07-01

    The major construction materials for the magnet area, as they are the superconductor, the stabilizer, solders, electric and thermal insulations are reviewed concerning the optimal data achieved so far for the specific use in fusion. The magnet technology for fusion is already well advanced, so that sufficient material data are available for design purposes, but with one important exception, the irradiation damage behaviour. The paper tries to review the state of the art specifically in this resp'ect. Irradiation data on the superconductors have in most cases not been measured in a fusion project relevant manner, e.g. in-situ 4 K measurements of prototype conductors with stabilizer and solder bond are missing. For the wide spread amount on organic insulations, polyimide based systems show better irradiation resistance than epoxy based materials, but the later are the major ones used in magnet technology. The interpretation of all data available so far allows still both an optimistic and a conservative point of view on irradiation limits for the magnet materials. Not underestimated should be the importance of a very high strength low temperature steel for the conductor/winding structure, because it occupies a large fraction of the overall cross section and implies a good potential for savings or current density increase.

  10. Skyrmions in magnetic materials

    CERN Document Server

    Seki, Shinichiro

    2016-01-01

    This brief reviews current research on magnetic skyrmions, with emphasis on formation mechanisms, observation techniques, and materials design strategies. The response of skyrmions, both static and dynamical, to various electromagnetic fields is also covered in detail. Recent progress in magnetic imaging techniques has enabled the observation of skyrmions in real space, as well as the analysis of their ordering manner and the details of their internal structure. In metallic systems, conduction electrons moving through the skyrmion spin texture gain a nontrivial quantum Berry phase, which provides topological force to the underlying spin texture and enables the current-induced manipulation of magnetic skyrmions. On the other hand, skyrmions in an insulator can induce electric polarization through relativistic spin-orbit interaction, paving the way for the control of skyrmions by an external electric field without loss of Joule heating. Because of its nanometric scale, particle nature, and electric controllabil...

  11. Ligand-Stabilized Reduced-Dimensionality Perovskites

    KAUST Repository

    Quan, Li Na

    2016-02-03

    Metal halide perovskites have rapidly advanced thin film photovoltaic performance; as a result, the materials’ observed instabilities urgently require a solution. Using density functional theory (DFT), we show that a low energy of formation, exacerbated in the presence of humidity, explains the propensity of perovskites to decompose back into their precursors. We find, also using DFT, that intercalation of phenylethylammonium between perovskite layers introduces quantitatively appreciable van der Waals interactions; and these drive an increased formation energy and should therefore improve material stability. Here we report the reduced-dimensionality (quasi-2D) perovskite films that exhibit improved stability while retaining the high performance of conventional three-dimensional perovskites. Continuous tuning of the dimensionality, as assessed using photophysical studies, is achieved by the choice of stoichiometry in materials synthesis. We achieved the first certified hysteresis-free solar power conversion in a planar perovskite solar cell, obtaining a 15.3% certified PCE, and observe greatly improved performance longevity.

  12. Magnetism and metallurgy of soft magnetic materials

    CERN Document Server

    Chen, Chih-Wen

    2011-01-01

    Soft magnetic materials are economically and technologically the most important of all magnetic materials. In particular, the development of new materials and novel applications for the computer and telecommunications industries during the past few decades has immensely broadened the scope and altered the nature of soft magnetic materials. In addition to metallic substances, nonmetallic compounds and amorphous thin films are coming increasingly important. This thorough, well-organized volume - on of the most comprehensive treatments available - offers a coherent, logical presentation of the p

  13. Topological excitations in magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Bazeia, D., E-mail: bazeia@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, 58051-970 João Pessoa, PB (Brazil); Doria, M.M. [Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro (Brazil); Dipartimento di Fisica, Università di Camerino, I-62032 Camerino (Italy); Rodrigues, E.I.B. [Departamento de Física, Universidade Federal da Paraíba, 58051-970 João Pessoa, PB (Brazil)

    2016-05-20

    In this work we propose a new route to describe topological excitations in magnetic systems through a single real scalar field. We show here that spherically symmetric structures in two spatial dimensions, which map helical excitations in magnetic materials, admit this formulation and can be used to model skyrmion-like structures in magnetic materials.

  14. High performance soft magnetic materials

    CERN Document Server

    2017-01-01

    This book provides comprehensive coverage of the current state-of-the-art in soft magnetic materials and related applications, with particular focus on amorphous and nanocrystalline magnetic wires and ribbons and sensor applications. Expert chapters cover preparation, processing, tuning of magnetic properties, modeling, and applications. Cost-effective soft magnetic materials are required in a range of industrial sectors, such as magnetic sensors and actuators, microelectronics, cell phones, security, automobiles, medicine, health monitoring, aerospace, informatics, and electrical engineering. This book presents both fundamentals and applications to enable academic and industry researchers to pursue further developments of these key materials. This highly interdisciplinary volume represents essential reading for researchers in materials science, magnetism, electrodynamics, and modeling who are interested in working with soft magnets. Covers magnetic microwires, sensor applications, amorphous and nanocrystalli...

  15. Experiments on Magnetic Materials

    Science.gov (United States)

    Schneider, C. S.; Ertel, John P.

    1978-01-01

    Describes the construction and use of a simple apparatus to measure the magnetization density and magnetic susceptibility of ferromagnetic, paramagnetic, and the diamagnetic solids and liquids. (Author/GA)

  16. Bragg diffraction from magnetic materials

    DEFF Research Database (Denmark)

    Lebech, B.

    2002-01-01

    -ray scattering when studying crystalline properties of matter. In addition, neutrons possess magnetic moments of the same order of magnitude as the atomic magnetic moments in elements and this makes neutrons highly suited for studies of the order and interactions between the magnetic moments in magnetic...... materials. This will be illustrated by reviewing the ordered magnetic structures found in some simple elements and in some chemically more complex systems containing several magnetic elements. The different scattering techniques (two- and three-axis neutron scattering, small angle neutron scattering...

  17. Nanostructured electronic and magnetic materials

    Indian Academy of Sciences (India)

    Research and development in nanostructured materials is one of the most intensely studied areas in science. As a result of concerted R & D efforts, nanostructured electronic and magnetic materials have achieved commercial success. Specific examples of novel industrially important nanostructured electronic and magnetic ...

  18. Magnetic Materials for Current Transformers

    CERN Document Server

    Aguilera, S; Ruffieux, P

    2013-01-01

    At CERN, the circulating beam current measurement is provided by two types of transformers, the Direct Current Current Transformers (DCCT) and the Fast Beam Current Transformers (FBCT). Each type of transformer requires different magnetic characteristics regarding parameters such as permeability, coercivity and shape of the magnetization curve. Each transformer is built based on toroidal cores of a magnetic material which gives these characteristics. For example, DCCTs consist of three cores, two for the measurement of the DC component and one for the AC component. In order to study the effect of changes in these parameters on the current transformers, several interesting raw materials based on their as-cast properties were selected with the annealing process used to tune their properties for the individual needs of each transformer. First annealing tests show that the magnetization curve, and therefore the permeability, of the material can be modified, opening the possibility for building and studying a vari...

  19. Magnetic bubble materials.

    Science.gov (United States)

    Giess, E A

    1980-05-23

    Physicists, materials scientists, and engineers combined to bring solid-state bubble devices into the computer memory and recording marketplace. Devices with smaller bubbles are being developed for increased data capacity and lower cost. Epitaxial garnet films made by isothermal dipping in molten solutions helped put the technology in place and will probably satisfy the material needs of future devices with bubbles scaled down from 2 to 0.5 micrometer in size.

  20. TOPICAL REVIEW: Electron holography of magnetic materials

    Science.gov (United States)

    Shindo, Daisuke; Murakami, Yasukazu

    2008-09-01

    Electron holography, which visualizes magnetic and/or electric fields in materials on the nanometre scale, is a powerful tool for the study of fundamental issues in physics as well as the characterization of advanced materials. This paper presents an overview of recent electron holography studies on advanced magnetic materials, which include hard magnetic materials (both nucleation-type and pinning-type magnets), soft magnetic materials (both classical alloys and recently developed nanostructured materials), magnetic recording materials (Co-CoO tape and other related topics) and magnetic functional materials (ferromagnetic shape memory alloys and colossal magnetoresistive manganites).

  1. Superconducting materials suitable for magnets

    CERN Multimedia

    CERN. Geneva. Audiovisual Unit

    2002-01-01

    The range of materials available for superconducting magnets is steadily expanding, even as the choice of material becomes potentially more complex. When virtually all magnets were cooled by helium at ~2-5 K it was easy to separate the domain of Nb-Ti from those of Nb3Sn applications and very little surprise that more than 90% of all magnets are still made from Nb-Ti. But the development of useful conductors of the Bi-Sr-Ca-Cu-O and YBa2Cu3Ox high temperature superconductors, coupled to the recent discovery of the 39 K superconductor MgB2 and the developing availability of cryocoolers suggests that new classes of higher temperature, medium field magnets based on other than Nb-based conductors could become available in the next 5-10 years. My talks will discuss the essential physics and materials science of these 5 classes of material - Nb-Ti, Nb3Sn, MgB2, Bi-Sr-Ca-Cu-O and YBa2Cu3Ox - in the context of those aspects of their science, properties and fabrication properties, which circumscribe their applications...

  2. Method and apparatus for separating materials magnetically

    Science.gov (United States)

    Hise, Jr., Eugene C.; Holman, Allen S.

    1982-01-01

    Magnetic and non-magnetic materials are separated by passing stream thereof past coaxial current-carrying coils which produce a magnetic field wherein intensity varies sharply with distance radially of the axis of the coils.

  3. Fundamentals and applications of magnetic materials

    CERN Document Server

    Krishnan, Kannan M

    2016-01-01

    Students and researchers looking for a comprehensive textbook on magnetism, magnetic materials and related applications will find in this book an excellent explanation of the field. Chapters progress logically from the physics of magnetism, to magnetic phenomena in materials, to size and dimensionality effects, to applications. Beginning with a description of magnetic phenomena and measurements on a macroscopic scale, the book then presents discussions of intrinsic and phenomenological concepts of magnetism such as electronic magnetic moments and classical, quantum, and band theories of magnetic behavior. It then covers ordered magnetic materials (emphasizing their structure-sensitive properties) and magnetic phenomena, including magnetic anisotropy, magnetostriction, and magnetic domain structures and dynamics. What follows is a comprehensive description of imaging methods to resolve magnetic microstructures (domains) along with an introduction to micromagnetic modeling. The book then explores in detail size...

  4. Physics and measurements of magnetic materials

    CERN Document Server

    Sgobba, S

    2010-01-01

    Magnetic materials, both hard and soft, are used extensively in several components of particle accelerators. Magnetically soft iron-nickel alloys are used as shields for the vacuum chambers of accelerator injection and extraction septa; Fe-based material is widely employed for cores of accelerator and experiment magnets; soft spinel ferrites are used in collimators to damp trapped modes; innovative materials such as amorphous or nanocrystalline core materials are envisaged in transformers for high-frequency polyphase resonant convertors for application to the International Linear Collider (ILC). In the field of fusion, for induction cores of the linac of heavy-ion inertial fusion energy accelerators, based on induction accelerators requiring some 107 kg of magnetic materials, nanocrystalline materials would show the best performance in terms of core losses for magnetization rates as high as 105 T/s to 107 T/s. After a review of the magnetic properties of materials and the different types of magnetic behaviour...

  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. Magnetic imaging and its applications to materials

    CERN Document Server

    De Graef, Marc

    2000-01-01

    Volume 36 provides an extensive introduction to magnetic imaging,including theory and practice, utilizing a wide range of magnetic sensitive imaging methods. It also illustrates the applications of these modern experimental techniques together with imaging calculations to today's advanced magnetic materials. This book is geared towards the upper-level undergraduate students and entry-level graduate students majoring in physics or materials science who are interested in magnetic structure and magnetic imaging. Researchers involved in studying magnetic materials should alsofind the book usef

  7. Neutron scattering of advanced magnetic materials

    Science.gov (United States)

    Yusuf, S. M.; Kumar, Amit

    2017-09-01

    An overview of notable contributions of neutron scattering in the advancement of magnetic materials has been presented. A brief description of static neutron scattering techniques, viz., diffraction, depolarization, small angle scattering, and reflectivity, employed in the studies of advanced magnetic materials, is given. Apart from providing the up-to-date literature, this review highlights the importance of neutron scattering techniques in achieving microscopic as well as mesoscopic understanding of static magnetic properties of the following selective classes of advanced magnetic materials: (i) magnetocaloric materials, (ii) permanent magnets, (iii) multiferroic materials, (iv) spintronic materials, and (v) molecular magnetic materials. In the area of magnetocaloric materials, neutron diffraction studies have greatly improved the understanding of magneto-structural coupling by probing (i) atomic site distribution, (ii) evolution of structural phases and lattice parameters across the TC, and (iii) microscopic details of magnetic ordering in several potential magnetocaloric materials. Such an understanding is vital to enhance the magnetocaloric effect. Structural and magnetic investigations, employing neutron diffraction and allied techniques, have helped to improve the quality of permanent magnets by tailoring (understanding) structural phases, magnetic ordering, crystallinity, microstructure (texture), and anisotropy. The neutron diffraction studies of structural distortions/instabilities and magnetic ordering in multiferroic materials have improved the microscopic understanding of magnetoelectric coupling that allows one to control magnetic order by an electric field and electric order by a magnetic field in multiferroic materials. In the field of molecular magnetic materials, neutron diffraction studies have enhanced the understanding of (i) structural and magnetic ordering, (ii) short-range structural and magnetic correlations, (iii) spin density distribution

  8. Materials for room temperature magnetic refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Rosendahl Hansen, B.

    2010-07-15

    Magnetic refrigeration is a cooling method, which holds the promise of being cleaner and more efficient than conventional vapor-compression cooling. Much research has been done during the last two decades on various magnetic materials for this purpose and today a number of materials are considered candidates as they fulfill many of the requirements for a magnetic refrigerant. However, no one material stands out and the field is still active with improving the known materials and in the search for a better one. Magnetic cooling is based on the magnetocaloric effect, which causes a magnetic material to change its temperature when a magnetic field is applied or removed. For room temperature cooling, one utilizes that the magnetocaloric effect peaks near magnetic phase transitions and so the materials of interest all have a critical temperature within the range of 250 - 310 K. A magnetic refrigerant should fulfill a number of criteria, among these a large magnetic entropy change, a large adiabatic temperature change, preferably little to no thermal or magnetic hysteresis and the material should have the stability required for long term use. As the temperature range required for room temperature cooling is some 40 - 50 K, the magnetic refrigerant should also be able to cover this temperature span either by exhibiting a very broad peak in magnetocaloric effect or by providing the opportunity for creating a materials series with varying transition temperatures. (Author)

  9. Thin Magnetically Soft Wires for Magnetic Microsensors

    Directory of Open Access Journals (Sweden)

    Arcady Zhukov

    2009-11-01

    Full Text Available Recent advances in technology involving magnetic materials require development of novel advanced magnetic materials with improved magnetic and magneto-transport properties and with reduced dimensionality. Therefore magnetic materials with outstanding magnetic characteristics and reduced dimensionality have recently gained much attention. Among these magnetic materials a family of thin wires with reduced geometrical dimensions (of order of 1–30 μm in diameter have gained importance within the last few years. These thin wires combine excellent soft magnetic properties (with coercivities up to 4 A/m with attractive magneto-transport properties (Giant Magneto-impedance effect, GMI, Giant Magneto-resistance effect, GMR and an unusual re-magnetization process in positive magnetostriction compositions exhibiting quite fast domain wall propagation. In this paper we overview the magnetic and magneto-transport properties of these microwires that make them suitable for microsensor applications.

  10. Magnetism and Structure in Functional Materials

    CERN Document Server

    Planes, Antoni; Saxena, Avadh

    2005-01-01

    Magnetism and Structure in Functional Materials addresses three distinct but related topics: (i) magnetoelastic materials such as magnetic martensites and magnetic shape memory alloys, (ii) the magnetocaloric effect related to magnetostructural transitions, and (iii) colossal magnetoresistance (CMR) and related magnanites. The goal is to identify common underlying principles in these classes of materials that are relevant for optimizing various functionalities. The emergence of apparently different magnetic/structural phenomena in disparate classes of materials clearly points to a need for common concepts in order to achieve a broader understanding of the interplay between magnetism and structure in this general class of new functional materials exhibiting ever more complex microstructure and function. The topic is interdisciplinary in nature and the contributors correspondingly include physicists, materials scientists and engineers. Likewise the book will appeal to scientists from all these areas.

  11. Magnetic Moment Distribution in Layered Materials

    Science.gov (United States)

    Nicholson, D. M. C.; Zhang, X.-G.; Wang, Y.; Shelton, W. A.; Butler, W. H.; Stocks, G. M.; MacLaren, J. M.

    1996-03-01

    Thin layers of magnetic material surrounded by non-magnetic layers display a reduced moment per atom relative to the bulk magnetic material. Plots of sturation magnetization versus magnetic layer thickness can be explained in terms of magnetically dead layers at interfaces. First principles calculations indicate a more complex distribution of magnetic moments. Moment distributions calculated in the local density approximation restricted to colinear spins and with unrestricted spin orientations will be presented for Cu/Ni/Cu, Cu/permalloy/Cu, and Mo/Ni/Mo structures. Work supported by Division of Materials Science, the Mathematical Information and Computational Science Division of the Office of Computational Technology Research, and by the Assistant Secretary of Defence Programs, Technology Management Group, Technology Transfer Initiative, US DOE under subcontract DEAC05-84OR21400 with Martin-Marietta Energy Systems, Inc.

  12. Electronic states in systems of reduced dimensionality

    Energy Technology Data Exchange (ETDEWEB)

    Ulloa, S.E.

    1992-04-15

    This report briefly discusses the following research: magnetically modulated systems, inelastic magnetotunneling, ballistic transport review, screening in reduced dimensions, raman and electron energy loss spectroscopy; and ballistic quantum interference effects. (LSP).

  13. Materials for Room Temperature Magnetic Refrigeration

    DEFF Research Database (Denmark)

    Hansen, Britt Rosendahl

    Magnetic refrigeration is a cooling method, which holds the promise of being cleaner and more efficient than conventional vapor-compression cooling. Much research has been done during the last two decades on various magnetic materials for this purpose and today a number of materials are considere...... cooling is some 40 – 50 K, the magnetic refrigerant should also be able to cover this temperature span either by exhibiting a very broad peak in magnetocaloric effect or by providing the opportunity for creating a materials series with varying transition temperatures.......Magnetic refrigeration is a cooling method, which holds the promise of being cleaner and more efficient than conventional vapor-compression cooling. Much research has been done during the last two decades on various magnetic materials for this purpose and today a number of materials are considered...... candidates as they fulfill many of the requirements for a magnetic refrigerant. However, no one material stands out and the field is still active with improving the known materials and in the search for a better one. Magnetic cooling is based on the magnetocaloric effect, which causes a magnetic material...

  14. SQUID measurements of magnetization for a magnetically tagged composite material

    Science.gov (United States)

    Ma, Yu Pei; Wikswo, John P.; Fitzpatrick, Gerald

    2001-04-01

    Magnetic anomalies produced by a magnetically tagged composite material under stress may provide useful information for non-destructive inspection of the material. Magneto-optic methods (MOI) have been used previously to demonstrate that for a fiberglass and epoxy composite sample that is tagged with the magnetostrictive material Terfenol-D, tensile stress above a critical value alters the initial magnetization in regions near a structural defect. We have used a vector SQUID gradiometer, which can measure three components of the magnetic field, to study the stress response of the material. The SQUID detected a large remnant magnetization near the crack after degaussing without any applied tension. After the sample was magnetized, mainly in the z direction, the tensile stress reduces the magnetization Mz throughout the sample length, except that it increased (or decreased) the magnetization in the y direction in the immediate vicinity of the crack. For better understanding of the measured data, we also simulated three components of the magnetic field.

  15. Magnetic material arrangement in oriented termites: a magnetic resonance study

    Science.gov (United States)

    Alves, O. C.; Wajnberg, E.; de Oliveira, J. F.; Esquivel, D. M. S.

    2004-06-01

    Temperature dependence of the magnetic resonance is used to study the magnetic material in oriented Neocapritermes opacus (N.o.) termite, the only prey of the migratory ant Pachycondyla marginata (P.m.). A broad line in the g=2 region, associated to isolated nanoparticles shows that at least 97% of the magnetic material is in the termite's body (abdomen + thorax). From the temperature dependence of the resonant field and from the spectral linewidths, we estimate the existence of magnetic nanoparticles 18.5 ± 0.3 nm in diameter and an effective magnetic anisotropy constant, Keff between 2.1 and 3.2 × 10 4 erg/cm 3. A sudden change in the double integrated spectra at about 100 K for N.o. with the long body axis oriented perpendicular to the magnetic field can be attributed to the Verwey transition, and suggests an organized film-like particle system.

  16. Sintered soft magnetic materials. Properties and applications

    Science.gov (United States)

    Bas, J. A.; Calero, J. A.; Dougan, M. J.

    2003-01-01

    A comparison is presented of the characteristics and production requirements of a variety of materials used to produce sintered soft magnetic parts. These include pure iron, phosphorous-iron, silicon-iron, nickel-iron, and cobalt-iron, together with new coated materials based on encapsulated iron powders. In these bonded materials an organic and/or inorganic insulator is used to coat the metallic powder particles giving a magnetic composite. The suitability of the different materials for use in both direct and alternating current applications is reviewed, and examples are provided of their application in both the automotive and other sectors. The results of a comparative study of motors using stators and rotors based on both conventional laminated materials and the insulated iron powders are presented, in which the new materials show advantages of reduced hysteresis losses at high frequencies, and isotropy of magnetic properties. Nevertheless, the applications of these materials in electrical motors requires the modification of existing designs.

  17. Nanostructured electronic and magnetic materials

    Indian Academy of Sciences (India)

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

    analytical chemistry, drug delivery, bioencapsulation, and in electronic, magnetic, optical and mechanical devices. ... The reaction governing electrochromism, which basically is a reversible coloration process under the .... 3.3a Storage applications: The route to progress in memory technology is cost reduction and the ...

  18. Electronic structure and magnetism of complex materials

    CERN Document Server

    Papaconstantopoulos, D A

    2003-01-01

    Recent developments in electronic structure theory have led to a new understanding of magnetic materials at the microscopic level. This enables a truly first-principles approach to investigations of technologically important magnetic materials. Among these advances have been practical schemes for handling non-collinear magnetic systems, including relativity, understanding of the origins and role of orbital magnetism within band structure formalisms, density functional approaches for magnons and low-lying spin excitations, understanding of the interplay of orbital, spin and lattice orderings in complex oxides, transport theories for layered systems, and the theory of magnetic interactions in doped semiconductors. The book covers these recent developments with review articles by some of the main originators of these advances.

  19. Magnetic Nanostructures and Spintronic Materials

    Energy Technology Data Exchange (ETDEWEB)

    Pechan, Michael [Miami Univ., Oxford, OH (United States)

    2016-01-26

    Over the 28 years of this grant, the PI explored magnetodynamics and magnetostatics in wide-ranging topics such as spin-glasses, exchange springs, exchange bias, perpendicular anisotropy, multiferroics, metal organic frameworks, magnetic vortices, core/shell nanoparticles and laterally confined spin waves. There was even a foray into superconductivity following the Woodstock of Physics in 1987. The work was performed in the context of an undergraduate and Masters program utilizing electron magnetic resonance as a primary research tool, although developments were also made in magneto-optical Kerr effect, torque and vibrating sample magnetometry. The work was largely done in collaboration with scientists from other universities and industrial laboratories both within the US and internationally.

  20. Handbook of magnetic materials, v. 19

    CERN Document Server

    2011-01-01

    Volume 19 of the Handbook of Magnetic Materials, as the preceding volumes, has a dual purpose. As a textbook it is intended to help those who wish to be introduced to a given topic in the field of magnetism without the need to read the vast amount of literature published. As a work of reference it is intended for scientists active in magnetism research. To this dual purpose, Volume 19 is composed of topical review articles written by leading authorities. In each of these articles an extensive description is given in graphical as well as in tabular form, much emphasis being placed on the discussion of the experimental material in the framework of physics, chemistry and material science. It provides readers with novel trends and achievements in magnetism.

  1. Magnetization and magnetostriction in highly magnetostrictive materials

    Energy Technology Data Exchange (ETDEWEB)

    Thoelke, Jennifer Beth [Iowa State Univ., Ames, IA (United States)

    1993-05-26

    The majority of this research has been in developing a model to describe the magnetostrictive properties of Terfenol-D, Tbsub>1-xDyxFey (x = 0.7-0.75 and y = 1.8--2.0), a rare earth-iron alloy which displays much promise for use in device applications. In the first chapter an introduction is given to the phenomena of magnetization and magnetostriction. The magnetic processes responsible for the observed magnetic properties of materials are explained. An overview is presented of the magnetic properties of rare earths, and more specifically the magnetic properties of Terfenol-D. In the second chapter, experimental results are presented on three composition of Tb< with x = 0.7, y= 1.9, 1.95, and x= 0.73, y= 1.95. The data were taken for various levels of prestress to show the effects of composition and microstructure on the magnetic and magnetostrictive properties of Terfenol-D. In the third chapter, a theoretical model is developed based on the rotation of magnetic domains. The model is used to explain the magnetic and magnetostrictive properties of Terfenol-D, including the observed negative strictions and large change in strain. The fourth chapter goes on to examine the magnetic properties of Terfenol-D along different crystallographic orientations. In the fifth chapter initial data are presented on the time dependence of magnetization in nickel.

  2. Designing magnetic composite materials using aqueous magnetic fluids

    CERN Document Server

    Galicia, J A; Cousin, F; Guemghar, D; Menager, C; Cabuil, V

    2003-01-01

    In this paper, we report on how to take advantage of good knowledge of both the chemistry and the stability of an aqueous magnetic colloidal suspension to realize different magnetic composites. The osmotic pressure of the magnetic nanoparticles is set prior to the realization of the composite to a given value specially designed for the purpose for each hybrid material: magnetic particles in polymer networks, particles as probes for studying the structure of clay suspensions and shape modification of giant liposomes. First, we show that the introduction of magnetic particles in polyacrylamide gels enhances their Young modulus and reduces the swelling caused by water. The particles cause both a mechanical and an osmotic effect. The latter is strongly dependent on the ionic strength and is attributed to an attraction between particles and the polymeric matrix. In the second part, we determine the microscopic structure of suspensions of laponite as a function of concentration, by combining SANS and magneto-optica...

  3. Levitating a Magnet Using a Superconductive Material.

    Science.gov (United States)

    Juergens, Frederick H.; And Others

    1987-01-01

    Presented are the materials and a procedure for demonstrating the levitation of a magnet above a superconducting material. The demonstration can be projected with an overhead projector for a large group of students. Kits to simplify the demonstration can be purchased from the Institute for Chemical Education of the University of Wisconsin-Madison.…

  4. Superconductivity and magnetism: Materials properties and developments

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, N.H.; Bay, N.; Grivel, J.C. (eds.) [and others

    2003-07-01

    The 24th Risoe International Symposium on Materials Science focuses on development of new materials, devices and applications, as well as experimental and theoretical studies of novel and unexplained phenomena in superconductivity and magnetism, e.g. within high.T{sub c} superconductivity, magnetic superconductors, MgB{sub 2}, CMR materials, nanomagnetism and spin-tronics. The aim is to stimulate exchange of ideas and establish new collaborations between leading Danish and international scientists. The topics are addressed by presentations from 24 invited speakers and by 41 contributed papers. (ln)

  5. Correlation effects driven by reduced dimensionality in magnetic ...

    Indian Academy of Sciences (India)

    2015-06-02

    Jun 2, 2015 ... the role of electron correlations in dictating the electronic structure of this surface alloy. Similar behaviour has also been observed for c(2×2) Mn/Cu(1 0 0), c(2×2) Mn/Ni(1 0 0). [8,19] andc(2×2) Mn/Ag(1 0 0) [20] surface alloys and submonolayers of Mn on Fe(1 0 0). [21] substrates. For Mn films on Ni and Fe ...

  6. Magnetic spectroscopy and microscopy of functional materials

    Energy Technology Data Exchange (ETDEWEB)

    Jenkins, Catherine Ann [Univ. of Mainz (Germany)

    2011-05-01

    Heusler intermetallics Mn2Y Ga and X2MnGa (X; Y =Fe, Co, Ni) undergo tetragonal magnetostructural transitions that can result in half metallicity, magnetic shape memory, or the magnetocaloric effect. Understanding the magnetism and magnetic behavior in functional materials is often the most direct route to being able to optimize current materials for todays applications and to design novel ones for tomorrow. Synchrotron soft x-ray magnetic spectromicroscopy techniques are well suited to explore the the competing effects from the magnetization and the lattice parameters in these materials as they provide detailed element-, valence-, and site-specifc information on the coupling of crystallographic ordering and electronic structure as well as external parameters like temperature and pressure on the bonding and exchange. Fundamental work preparing the model systems of spintronic, multiferroic, and energy-related compositions is presented for context. The methodology of synchrotron spectroscopy is presented and applied to not only magnetic characterization but also of developing a systematic screening method for future examples of materials exhibiting any of the above effects. The chapter progression is as follows: an introduction to the concepts and materials under consideration (Chapter 1); an overview of sample preparation techniques and results, and the kinds of characterization methods employed (Chapter 2); spectro- and microscopic explorations of X2MnGa/Ge (Chapter 3); spectroscopic investigations of the composition series Mn2Y Ga to the logical Mn3Ga endpoint (Chapter 4); and a summary and overview of upcoming work (Chapter 5). Appendices include the results of a Think Tank for the Graduate School of Excellence MAINZ (Appendix A) and details of an imaging project now in progress on magnetic reversal and domain wall observation in the classical Heusler material Co2FeSi (Appendix B).

  7. Electronic, Optical, and Thermal Properties of Reduced-Dimensional Semiconductors

    Science.gov (United States)

    Huang, Shouting

    Reduced-dimensional materials have attracted tremendous attention because of their new physics and exotic properties, which are of great interests for fundamental science. More importantly, the manipulation and engineering of matter on an atomic scale yield promising applications for many fields including nanoelectronics, nanobiotechnology, environments, and renewable energy. Because of the unusual quantum confinement and enhanced surface effect of reduced-dimensional materials, traditional empirical models suffer from necessary but unreliable parameters extracted from previously-studied bulk materials. In this sense, quantitative, parameter-free approaches are highly useful for understanding properties of reduced-dimensional materials and, furthermore, predicting their novel applications. The first-principles density functional theory (DFT) is proven to be a reliable and convenient tool. In particular, recent progress in many-body perturbation theory (MBPT) makes it possible to calculate excited-state properties, e.g., quasiparticle (QP) band gap and optical excitations, by the first-principles approach based on DFT. Therefore, during my PhD study, I employed first-principles calculations based on DFT and MBPT to systematically study fundamental properties of typical reduced-dimensional semiconductors, i.e., the electronic structure, phonons, and optical excitations of core-shell nanowires (NWs) and graphene-like two-dimensional (2D) structures of current interests. First, I present first-principles studies on how to engineer band alignments of nano-sized radial heterojunctions, Si/Ge core-shell NWs. Our calculation reveals that band offsets in these one-dimensional (1D) nanostructures can be tailored by applying axial strain or varying core-shell sizes. In particular, the valence band offset can be efficiently tuned across a wide range and even be diminished via applied strain. Two mechanisms contribute to this tuning of band offsets. Furthermore, varying the

  8. Magnetic and Superconducting Materials at High Pressures

    Energy Technology Data Exchange (ETDEWEB)

    Struzhkin, Viktor V. [Carnegie Inst. of Washington, Washington, DC (United States)

    2015-03-24

    The work concentrates on few important tasks in enabling techniques for search of superconducting compressed hydrogen compounds and pure hydrogen, investigation of mechanisms of high-Tc superconductivity, and exploring new superconducting materials. Along that route we performed several challenging tasks, including discovery of new forms of polyhydrides of alkali metal Na at very high pressures. These experiments help us to establish the experimental environment that will provide important information on the high-pressure properties of hydrogen-rich compounds. Our recent progress in RIXS measurements opens a whole field of strongly correlated 3d materials. We have developed a systematic approach to measure major electronic parameters, like Hubbard energy U, and charge transfer energy Δ, as function of pressure. This technique will enable also RIXS studies of magnetic excitations in iridates and other 5d materials at the L edge, which attract a lot of interest recently. We have developed new magnetic sensing technique based on optically detected magnetic resonance from NV centers in diamond. The technique can be applied to study superconductivity in high-TC materials, to search for magnetic transitions in strongly correlated and itinerant magnetic materials under pressure. Summary of Project Activities; development of high-pressure experimentation platform for exploration of new potential superconductors, metal polyhydrides (including newly discovered alkali metal polyhydrides), and already known superconductors at the limit of static high-pressure techniques; investigation of special classes of superconducting compounds (high-Tc superconductors, new superconducting materials), that may provide new fundamental knowledge and may prove important for application as high-temperature/high-critical parameter superconductors; investigation of the pressure dependence of superconductivity and magnetic/phase transformations in 3d transition metal compounds, including

  9. Final Technical Progress Report NANOSTRUCTURED MAGNETIC MATERIALS

    Energy Technology Data Exchange (ETDEWEB)

    Charles M. Falco

    2012-09-13

    This report describes progress made during the final phase of our DOE-funded program on Nanostructured Magnetic Materials. This period was quite productive, resulting in the submission of three papers and presentation of three talks at international conferences and three seminars at research institutions. Our DOE-funded research efforts were directed toward studies of magnetism at surfaces and interfaces in high-quality, well-characterized materials prepared by Molecular Beam Epitaxy (MBE) and sputtering. We have an exceptionally well-equipped laboratory for these studies, with: Thin film preparation equipment; Characterization equipment; Equipment to study magnetic properties of surfaces and ultra-thin magnetic films and interfaces in multi-layers and superlattices.

  10. A Reptation Model for Magnetic Materials

    Science.gov (United States)

    2006-01-01

    A Reptation Model for Magnetic Materials Thomas R. Braun ∗, Ralph C. Smith † and Marcelo J. Dapino ‡ ∗Center for Research in Scientific Computation...North Carolina State Univ., Raleigh, NC 27695 †Department of Mechanical Engineering, The Ohio State University, Columbus, OH 43210 Abstract Reptation ...comprehensive material characterization or model-based control design. Because the microscopic mechanisms which cause reptation are complex, we characterize

  11. Magnetic Levitational Assembly for Living Material Fabrication.

    Science.gov (United States)

    Tasoglu, Savas; Yu, Chu Hsiang; Liaudanskaya, Volha; Guven, Sinan; Migliaresi, Claudio; Demirci, Utkan

    2015-07-15

    Functional living materials with microscale compositional topographies are prevalent in nature. However, the creation of biomaterials composed of living micro building blocks, each programmed by composition, functionality, and shape, is still a challenge. A powerful yet simple approach to create living materials using a levitation-based magnetic method is presented. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Giant magnetoresistance materials for magnetic recording technology

    Energy Technology Data Exchange (ETDEWEB)

    Heffner, R.H.; Adams, C.D.; Brosha, E.L. [and others

    1997-12-01

    This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). This work focused on a class of transition-metal-oxide (TMO) materials (LaMnO{sub 3} doped with Ca, Ba, or Sr) that exhibits an insulator-to-metal transition near a ferromagnetic phase transition temperature. This yields a very large magnetoresistance; thus these materials may have important uses as magnetic sensors in a variety of applications, ranging from automobiles to read heads for magnetic storage. In addition, the transport current in the ferromagnetic state is likely to be very highly polarized, which means that additional device applications using the phenomena of spin-polarized tunneling can be envisioned. Use of these materials as magnetic sensors depends upon learning to control the synthesis parameters (principally temperature, pressure and composition) to achieve a specific carrier concentration and/or mobility. A second challenge is the high magnetic fields ({ge}1 Tesla) currently required to achieve a large change in resistance. The authors began an investigation of two novel approaches to this field-sensitivity problem, involving the development of multilayer structures of the TMO materials. Finally, they began to explore the use of epitaxial strain as a means of changing the transport properties in thin-film multilayers.

  13. Thermoinduced magnetization in nanoparticles of antiferromagnetic materials

    DEFF Research Database (Denmark)

    Mørup, Steen; Frandsen, Cathrine

    2004-01-01

    We show that there is a thermoinduced contribution to the magnetic moment of nanoparticles of antiferromagnetic materials. It arises from thermal excitations of the uniform spin-precession mode, and it has the unusual property that its magnitude increases with increasing temperature. This has the...

  14. Alignment of molecular materials in high magnetic fields

    NARCIS (Netherlands)

    Christianen, P.C.M.; Shklyarevskiy, O.I.; Boamfa, M.I.; Maan, J.C.

    2004-01-01

    The potential of using high magnetic fields to align functional molecular materials is discussed, illustrated by magnetic orientation of two different types of materials. Alignment of side chain polymer liquid crystals leads to macroscopically ordered, transparant and strongly birefringent material.

  15. Dynamic Characterization of Thin Film Magnetic Materials

    Science.gov (United States)

    Gu, Wei

    A broadband dynamic method for characterizing thin film magnetic material is presented. The method is designed to extract the permeability and linewidth of thin magnetic films from measuring the reflection coefficient (S11) of a house-made and short-circuited strip line testing fixture with or without samples loaded. An adaptive de-embedding method is applied to remove the parasitic noise of the housing. The measurements were carried out with frequency up to 10GHz and biasing magnetic fields up to 600 Gauss. Particular measurement setup and 3-step experimental procedures are described in detail. The complex permeability of a 330nm thick continuous FeGaB, 435nm thick laminated FeGaB film and a 100nm thick NiFe film will be induced dynamically in frequency-biasing magnetic field spectra and compared with a theoretical model based on Landau-Lifshitz-Gilbert (LLG) equations and eddy current theories. The ferromagnetic resonance (FMR) phenomenon can be observed among these three magnetic materials investigated in this thesis.

  16. Magnetic and electrical control of engineered materials

    Science.gov (United States)

    Schuller, Ivan K.; de La Venta Granda, Jose; Wang, Siming; Ramirez, Gabriel; Erekhinskiy, Mikhail; Sharoni, Amos

    2016-08-16

    Methods, systems, and devices are disclosed for controlling the magnetic and electrical properties of materials. In one aspect, a multi-layer structure includes a first layer comprising a ferromagnetic or ferrimagnetic material, and a second layer positioned within the multi-layer structure such that a first surface of the first layer is in direct physical contact with a second surface of the second layer. The second layer includes a material that undergoes structural phase transitions and metal-insulator transitions upon experiencing a change in temperature. One or both of the first and second layers are structured to allow a structural phase change associated with the second layer cause a change magnetic properties of the first layer.

  17. Magnetic levitation from negative permeability materials

    Energy Technology Data Exchange (ETDEWEB)

    Coffey, Mark W., E-mail: mcoffey@mines.edu [Department of Physics, Colorado School of Mines, Golden, CO 80401 (United States)

    2012-09-03

    As left-handed materials and metamaterials are becoming more prevalent, we examine the effect of negative permeability upon levitation force. We first consider two half spaces of differing permeability and a point magnetic source, so that the method of images may be employed. We determine that the resulting force may be larger than for conventional magnetic materials. We then illustrate the inclusion of a finite sample thickness. -- Highlights: ► The effect of negative permeability upon levitation force is considered. ► Such an effect could be realized with metamaterials. ► The resulting force may be larger than with conventional materials. ► The analysis is extended to allow for a finite sample thickness. ► Representative numerical values are given.

  18. Optimizing Energy Conversion: Magnetic Nano-materials

    Science.gov (United States)

    McIntyre, Dylan; Dann, Martin; Ilie, Carolina C.

    2015-03-01

    We present herein the work started at SUNY Oswego as a part of a SUNY 4E grant. The SUNY 4E Network of Excellence has awarded SUNY Oswego and collaborators a grant to carry out extensive studies on magnetic nanoparticles. The focus of the study is to develop cost effective rare-earth-free magnetic materials that will enhance energy transmission performance of various electrical devices (solar cells, electric cars, hard drives, etc.). The SUNY Oswego team has started the preliminary work for the project and graduate students from the rest of the SUNY 4E team (UB, Alfred College, Albany) will continue the project. The preliminary work concentrates on analyzing the properties of magnetic nanoparticle candidates, calculating molecular orbitals and band gap, and the fabrication of thin films. SUNY 4E Network of Excellence Grant.

  19. Hybrid nanostructured materials with tunable magnetic characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Martínez, Nubia E.; Garza-Navarro, M. A., E-mail: marco.garzanr@uanl.edu.mx; García-Gutiérrez, Domingo; González-González, Virgilio A.; Torres-Castro, Alejandro; Ortiz-Méndez, U. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica (Mexico)

    2014-12-15

    We report on the development of hybrid nanostructured materials (HNM) based on spinel-metal-oxide nanoparticles (SMON) stabilized in carboxymethyl-cellulose (CMC)/cetyltrimethyl-ammonium-bromide (CTAB) templates, with tunable magnetic characteristics. These HNM were synthesized using a one-pot chemical approach to obtain CMC/CTAB templates with controllable size and morphology, where the SMON could be densely arranged. The synthesized HNM were characterized by transmission electron microscopy and its related techniques, such as bright field (BF) and Z-contrast (HAADF-STEM) imaging, and selected area electron diffraction, as well as static magnetic measuring. Experimental evidence suggests that the morphology and size of the CMC/CTAB templates are highly dependent on the weight ratio of CTAB:SMON, as well as the hydration days of the CMC that is used for the synthesis of the HNM. Controlling these parameters allows modifying the density of the SMON arrangement in the CMC/CTAB templates. Moreover, magnetic features such as remanence, coercivity, and blocking/de-blocking processes of the particles’ magnetic moments are highly dependent on the interactions among the SMON assembled in the templates. Hence, the magnetic characteristics of HNM can be modulated or tuned by controlling the manner the SMON are arranged within the CMC/CTAB templates.

  20. Thermal contraction of superconducting magnet materials

    Science.gov (United States)

    Gladky, V. N.; Kozub, S. S.; Veshchikov, A. T.; Escher, U.

    This paper reports on the design of a quartz dilatometer used to measure the thermal contraction of structural glass cloth based laminates and of uniaxial glass fibre based laminates along and normal to the glass fibres within the 293-77 K and 293-4 K temperature ranges. The contraction of the structural and insulation materials and of the coil of the superconducting (SO magnets for the UNK was studied during cool-down from 300 to 4 K.

  1. Research on magnetic materials of interest in transportation

    Science.gov (United States)

    2000-04-01

    This paper reports the results of an investigation on magnetic materials of interest in the transportation field. It includes information about the present state of magnetic materials and examines the recently discovered phenomenon referred to as col...

  2. Magnetic filtration process, magnetic filtering material, and methods of forming magnetic filtering material

    Science.gov (United States)

    Taboada-Serrano, Patricia; Tsouris, Constantino; Contescu, Cristian I; McFarlane, Joanna

    2013-10-08

    The present invention provides magnetically responsive activated carbon, and a method of forming magnetically responsive activated carbon. The method of forming magnetically responsive activated carbon typically includes providing activated carbon in a solution containing ions of ferrite forming elements, wherein at least one of the ferrite forming elements has an oxidation state of +3 and at least a second of the ferrite forming elements has an oxidation state of +2, and increasing pH of the solution to precipitate particles of ferrite that bond to the activated carbon, wherein the activated carbon having the ferrite particles bonded thereto have a positive magnetic susceptibility. The present invention also provides a method of filtering waste water using magnetic activated carbon.

  3. Transport and magnetic properties in topological materials

    Science.gov (United States)

    Liang, Tian

    The notion of topology has been the central topic of the condensed matter physics in recent years, ranging from 2D quantum hall (QH) and quantum spin hall (QSH) states, 3D topological insulators (TIs), topological crystalline insulators (TCIs), 3D Dirac/Weyl semimetals, and topological superconductors (TSCs) etc. The key notion of the topological materials is the bulk edge correspondence, i.e., in order to preserve the symmetry of the whole system (bulk+edge), edge states must exist to counter-compensate the broken symmetry of the bulk. Combined with the fact that the bulk is topologically protected, the edge states are robust due to the bulk edge correspondence. This leads to interesting phenomena of chiral edge states in 2D QH, helical edge states in 2D QSH, "parity anomaly'' (time reversal anomaly) in 3D TI, helical edge states in the mirror plane of TCI, chiral anomaly in Dirac/Weyl semimetals, Majorana fermions in the TSCs. Transport and magnetic properties of topological materials are investigated to yield intriguing phenomena. For 3D TI Bi1.1Sb0.9Te 2S, anomalous Hall effect (AHE) is observed, and for TCI Pb1-x SnxSe, Seebeck/Nernst measurements reveal the anomalous sign change of Nernst signals as well as the massive Dirac fermions. Ferroelectricity and pressure measurements show that TCI Pb1-xSnxTe undergoes quantum phase transition (QPT) from trivial insulator through Weyl semimetal to anomalous insulator. Dirac semimetals Cd3As2, Na 3Bi show interesting results such as the ultrahigh mobility 10 7cm2V-1s-1 protected from backscattering at zero magnetic field, as well as anomalous Nernst effect (ANE) for Cd3As2, and the negative longitudinal magnetoresistance (MR) due to chiral anomaly for Na3Bi. In-plane and out-of-plane AHE are observed for semimetal ZrTe5 by in-situ double-axes rotation measurements. For interacting system Eu2Ir2O7, full angle torque magnetometry measurements reveal the existence of orthogonal magnetization breaking the symmetry of

  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. Use of an apparatus for separating magnetic pieces of material

    NARCIS (Netherlands)

    Rem, P.C.; Berkhout, S.P.M.

    2010-01-01

    Using of an apparatus for separating magnetic pieces of scrap-material of a first group from magnetic pieces of scrap- material of a second group, wherein a mixture of pieces of scrap-material from the first group and from the second group is collectively transported with a conveyor to a separating

  6. Mechanical and magnetic properties of composite materials with polymer matrix

    OpenAIRE

    Grujić A.; Talijan N.; Stojanović D.; Stajić-Trošić J.; Burzić Z.; Balanović Lj.; Aleksić R.

    2010-01-01

    Many of modern technologies require materials with unusual combinations of properties that cannot be met by the conventional metal alloys, ceramics, and polymeric materials. Material property combinations and ranges have been extended by the development of composite materials. Development of Nd-Fe-B/polymer composite magnetic materials has significantly increased interest in research and development of bonded magnets, since particles of Nd-Fe-B alloys are proved to be very suitable for their ...

  7. A novel magnetic valve using room temperature magnetocaloric materials

    DEFF Research Database (Denmark)

    Eriksen, Dan; Bahl, Christian; Pryds, Nini

    2012-01-01

    Magnetocaloric materials with near-room-temperature tuneable Curie temperatures have been utilized to develop a novel magnetic valve technology. The temperature dependent attractive force between the materials and a permanent magnet assembly is used to actuate valves as a response to temperature...... changes. This is made possible by the strong temperature dependence of the magnetization close to the Curie temperature of the magnetocaloric materials. Different compositions of both La0.67(Ca,Sr)0.33MnO3 and La(Fe,Co,Si)13 have been considered for use in prototype valves. Based on measured magnetization...... data a 3D finite element model has been set up to calculate the magnetic force between (graded) blocks of these materials and a permanent magnet assembly. The results have been used to calculate equilibrium points for actuation systems where the magnetic force is balanced by a spring force...

  8. Focus on Materials Analysis and Processing in Magnetic Fields

    Directory of Open Access Journals (Sweden)

    Yoshio Sakka, Noriyuki Hirota, Shigeru Horii and Tsutomu Ando

    2009-01-01

    Full Text Available Recently, interest in the applications of feeble (diamagnetic and paramagnetic magnetic materials has grown, whereas the popularity of ferromagnetic materials remains steady and high. This trend is due to the progress of superconducting magnet technology, particularly liquid-helium-free superconducting magnets that can generate magnetic fields of 10 T and higher. As the magnetic energy is proportional to the square of the applied magnetic field, the magnetic energy of such 10 T magnets is in excess of 10 000 times that of conventional 0.1 T permanent magnets. Consequently, many interesting phenomena have been observed over the last decade, such as the Moses effect, magnetic levitation and the alignment of feeble magnetic materials. Researchers in this area are widely spread around the world, but their number in Japan is relatively high, which might explain the success of magnetic field science and technology in Japan.Processing in magnetic fields is a rapidly expanding research area with a wide range of promising applications in materials science. The 3rd International Workshop on Materials Analysis and Processing in Magnetic Fields (MAP3, which was held on 14–16 May 2008 at the University of Tokyo, Japan, focused on various topics including magnetic field effects on chemical, physical, biological, electrochemical, thermodynamic and hydrodynamic phenomena; magnetic field effects on the crystal growth and processing of materials; diamagnetic levitation, the magneto-Archimedes effect, spin chemistry, magnetic orientation, control of structure by magnetic fields, magnetic separation and purification, magnetic-field-induced phase transitions, properties of materials in high magnetic fields, the development of NMR and MRI, medical applications of magnetic fields, novel magnetic phenomena, physical property measurement by magnetic fields, and the generation of high magnetic fields.This focus issue compiles 13 key papers selected from the proceedings

  9. Preparation of Magnetic Composite Materials: Experiments for Secondary School Students

    Czech Academy of Sciences Publication Activity Database

    Baldíková, Eva; Pospíšková, K.; Maděrová, Zdeňka; Šafaříková, Miroslava; Šafařík, Ivo

    2016-01-01

    Roč. 110, č. 1 (2016), s. 64-68 ISSN 0009-2770 Keywords : dyes removal * nanoparticles * mechanochemistry * technology * adsorbent * fe3o4 * magnet ic modification * magnet ic composite materials * magnet ic separation * microwave-assisted synthesis * mechanochemical synthesis Impact factor: 0.387, year: 2016

  10. Inkjet printing of magnetic materials with aligned anisotropy

    Science.gov (United States)

    Song, Han; Spencer, Jeremy; Jander, Albrecht; Nielsen, Jeffrey; Stasiak, James; Kasperchik, Vladek; Dhagat, Pallavi

    2014-05-01

    3-D printing processes, which use drop-on-demand inkjet printheads, have great potential in designing and prototyping magnetic materials. Unlike conventional deposition and lithography, magnetic particles in the printing ink can be aligned by an external magnetic field to achieve both high permeability and low hysteresis losses, enabling prototyping and development of novel magnetic composite materials and components, e.g., for inductor and antennae applications. In this work, we report an inkjet printing technique with magnetic alignment capability. Magnetic films with and without particle alignment are printed, and their magnetic properties are compared. In the alignment-induced hard axis direction, an increase in high frequency permeability and a decrease in hysteresis losses are observed. Our results suggest that unique magnetic structures with arbitrary controllable anisotropy, not feasible otherwise, may be fabricated via inkjet printing.

  11. FOREWORD: Focus on Materials Analysis and Processing in Magnetic Fields Focus on Materials Analysis and Processing in Magnetic Fields

    Science.gov (United States)

    Sakka, Yoshio; Hirota, Noriyuki; Horii, Shigeru; Ando, Tsutomu

    2009-03-01

    Recently, interest in the applications of feeble (diamagnetic and paramagnetic) magnetic materials has grown, whereas the popularity of ferromagnetic materials remains steady and high. This trend is due to the progress of superconducting magnet technology, particularly liquid-helium-free superconducting magnets that can generate magnetic fields of 10 T and higher. As the magnetic energy is proportional to the square of the applied magnetic field, the magnetic energy of such 10 T magnets is in excess of 10 000 times that of conventional 0.1 T permanent magnets. Consequently, many interesting phenomena have been observed over the last decade, such as the Moses effect, magnetic levitation and the alignment of feeble magnetic materials. Researchers in this area are widely spread around the world, but their number in Japan is relatively high, which might explain the success of magnetic field science and technology in Japan. Processing in magnetic fields is a rapidly expanding research area with a wide range of promising applications in materials science. The 3rd International Workshop on Materials Analysis and Processing in Magnetic Fields (MAP3), which was held on 14-16 May 2008 at the University of Tokyo, Japan, focused on various topics including magnetic field effects on chemical, physical, biological, electrochemical, thermodynamic and hydrodynamic phenomena; magnetic field effects on the crystal growth and processing of materials; diamagnetic levitation, the magneto-Archimedes effect, spin chemistry, magnetic orientation, control of structure by magnetic fields, magnetic separation and purification, magnetic-field-induced phase transitions, properties of materials in high magnetic fields, the development of NMR and MRI, medical applications of magnetic fields, novel magnetic phenomena, physical property measurement by magnetic fields, and the generation of high magnetic fields. This focus issue compiles 13 key papers selected from the proceedings of MAP3. Other

  12. High performance of low cost soft magnetic materials

    Indian Academy of Sciences (India)

    Administrator

    Abstract. The consistent interest in supporting research and development of magnetic materials during the last century is revealed in their steadily increasing market. In this work, the soft magnetic nanocrystalline. FINEMET alloy was prepared with commercial purity raw materials and compared for the first time with the.

  13. Experimental Tape Casting of Adjacently Graded Materials for Magnetic Refrigeration

    DEFF Research Database (Denmark)

    Bulatova, Regina

    graded thin films. The motivation to create such adjacently segmented structures stemmed from a search of material and a materials design alternative to the expensive rare earth element gadolinium which is widely used as a magnetic regenerator in the emerging magnetic refrigeration technology...

  14. High Field Pulse Magnets with New Materials

    Science.gov (United States)

    Li, L.; Lesch, B.; Cochran, V. G.; Eyssa, Y.; Tozer, S.; Mielke, C. H.; Rickel, D.; van Sciver, S. W.; Schneider-Muntau, H. J.

    2004-11-01

    High performance pulse magnets using the combination of CuNb conductor and Zylon fiber composite reinforcement with bore sizes of 24, 15 and 10 mm have been designed, manufactured and tested to destruction. The magnets successfully reached the peak fields of 64, 70 and 77.8 T respectively with no destruction. Failures occurred near the end flanges at the layer. The magnet design, manufacturing and testing, and the mode of the failure are described and analyzed.

  15. 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.

  16. A new class of natural magnetic materials - The ordering alloys

    Science.gov (United States)

    Wasilewski, Peter

    1988-01-01

    It is shown that tetrataenite (approximately FeNi), found in many meteorites, and Josephinite (approximately FeNi3), found in many serpentinized peridotites and possibly in Allende, are atomically ordered alloys. Data are presented, showing magnetic hysteresis loops, coercivity-temperature behavior at cryogenic temperatures, and thermomagnetic curves, that show that these ordered magnetic materials have unique magnetic properties and do not fit the conventional rock magnetism paradigms represented by Fe3O4 serpentinites. The ordered state is characterized by induced magnetic anisotropy, reaching the extreme for the tetragonal truly uniaxial anisotropy in FeNi. It is suggested that these ordered magnetic alloys should be considered a new class of natural magnetic materials.

  17. Structural materials for large superconducting magnets for tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Long, C.J.

    1976-12-01

    The selection of structural materials for large superconducting magnets for tokamak-type fusion reactors is considered. The important criteria are working stress, radiation resistance, electromagnetic interaction, and general feasibility. The most advantageous materials appear to be face-centered-cubic alloys in the Fe-Ni-Cr system, but high-modulus composites may be necessary where severe pulsed magnetic fields are present. Special-purpose structural materials are considered briefly.

  18. Phase-field modeling of microstructure evolutions in magnetic materials

    Science.gov (United States)

    Koyama, Toshiyuki

    2008-01-01

    Recently, the phase-field method has been extended and utilized across many fields of materials science. Since this method can incorporate, systematically, the effect of the coherency induced by lattice mismatch and the applied stress as well as the external electrical and magnetic fields, it has been applied to many material processes including solidification, solid-state phase transformations and various types of complex microstructure changes. In this paper, we focus on the recent phase-field simulations of real magnetic materials, and the simulation method for magnetic materials is explained comprehensively. Several applications of the phase-field method to clarifying the microstructure changes in magnetic materials, such as Ni2MnGa ferromagnetic shape memory alloy, FePt nanogranular thin film, Co–Sm–Cu rare-earth magnet, Fe–Cr–Co spinodal magnet, and Fe–C steel with external magnetic field, are demonstrated. Furthermore, the general concept of the effective strategy for controlling microstructure in magnetic materials is proposed. PMID:27877924

  19. Mechanical and magnetic properties of composite materials with polymer matrix

    Directory of Open Access Journals (Sweden)

    Grujić A.

    2010-01-01

    Full Text Available Many of modern technologies require materials with unusual combinations of properties that cannot be met by the conventional metal alloys, ceramics, and polymeric materials. Material property combinations and ranges have been extended by the development of composite materials. Development of Nd-Fe-B/polymer composite magnetic materials has significantly increased interest in research and development of bonded magnets, since particles of Nd-Fe-B alloys are proved to be very suitable for their production. This study investigates the mechanical and magnetic properties of compression molded Nd-Fe-B magnets with different content of magnetic powder in epoxy matrix. Mechanical properties were investigated at ambient temperature according to ASTM standard D 3039-00. The obtained results show that tensile strength and elongation decrease with an increase of Nd-Fe-B particles content in epoxy matrix. The modulus of elasticity increases, which means that in exploitation material with higher magnetic powder content, subjected to the same level of stress, undergoes 2 to 3.5 times smaller deformation. Scanning Electron Microscopy (SEM was used to examine the morphology of sample surfaces and fracture surfaces caused by the tensile strength tests. The results of SQUID magnetic measurements show an increase of magnetic properties of the investigated composites with increasing content of Nd-Fe-B particles.

  20. Modular Approaches to Flouride-Bridged Molecular Magnetic Materials

    DEFF Research Database (Denmark)

    Pedersen, Kasper Steen

    parameter make complexes with central ions from the 4d and 5d series particularly interesting building blocks for magnetic materials. The main obstacle is the common inherent lability of hexafluoridometallates towards hydrolysis, a tendency that is strongly diminished for several 4d and 5d [MF6]2– complexes...... spectroscopy. Lanthanides are interesting components for magnetic materials and have a huge underexplored potential in molecular magnetic systems. Advancements are, however, significantly hindered by their complicated electronic and magnetic nature. In this project, we have studied the properties of a class...

  1. MSWI boiler fly ashes: magnetic separation for material recovery.

    Science.gov (United States)

    De Boom, Aurore; Degrez, Marc; Hubaux, Paul; Lucion, Christian

    2011-07-01

    Nowadays, ferrous materials are usually recovered from Municipal Solid Waste Incineration (MSWI) bottom ash by magnetic separation. To our knowledge, such a physical technique has not been applied so far to other MSWI residues. This study focuses thus on the applicability of magnetic separation on boiler fly ashes (BFA). Different types of magnet are used to extract the magnetic particles. We investigate the magnetic particle composition, as well as their leaching behaviour (EN 12457-1 leaching test). The magnetic particles present higher Cr, Fe, Mn and Ni concentration than the non-magnetic (NM) fraction. Magnetic separation does not improve the leachability of the NM fraction. To approximate industrial conditions, magnetic separation is also applied to BFA mixed with water by using a pilot. BFA magnetic separation is economically evaluated. This study globally shows that it is possible to extract some magnetic particles from MSWI boiler fly ashes. However, the magnetic particles only represent from 23 to 120 g/kg of the BFA and, though they are enriched in Fe, are composed of similar elements to the raw ashes. The industrial application of magnetic separation would only be profitable if large amounts of ashes were treated (more than 15 kt/y), and the process should be ideally completed by other recovery methods or advanced treatments. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Utilizing Materials With Controllable Curie Temperatures for Magnetic Actuation Purposes

    DEFF Research Database (Denmark)

    Eriksen, Dan; Bahl, Christian R.H.; Smith, Anders

    2013-01-01

    The magnetic force between a permanent magnet and different blocks of ferromagnetic materials was measured and calculated as a function of distance and temperature in the vicinity of the Curie temperature of the materials. The calculations were carried out using a 3-D finite-element model...... of the system. On the basis of forces predicted by the model a number of equilibrium points were calculated for a system where the magnetic force on a ferromagnetic block of material is balanced by a linear spring force. It is shown how these calculation procedures can be used as a tool for designing autonomous...

  3. Magnetic Materials Suitable for Fission Power Conversion in Space Missions

    Science.gov (United States)

    Bowman, Cheryl L.

    2012-01-01

    Terrestrial fission reactors use combinations of shielding and distance to protect power conversion components from elevated temperature and radiation. Space mission systems are necessarily compact and must minimize shielding and distance to enhance system level efficiencies. Technology development efforts to support fission power generation scenarios for future space missions include studying the radiation tolerance of component materials. The fundamental principles of material magnetism are reviewed and used to interpret existing material radiation effects data for expected fission power conversion components for target space missions. Suitable materials for the Fission Power System (FPS) Project are available and guidelines are presented for bounding the elevated temperature/radiation tolerance envelope for candidate magnetic materials.

  4. 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...

  5. Magnetic properties of nano-multiferroic materials

    Science.gov (United States)

    Ramam, Koduri; Diwakar, Bhagavathula S.; Varaprasad, Kokkarachedu; Swaminadham, Veluri; Reddy, Venu

    2017-11-01

    Latent magnetization in the multiferroics can be achieved via the structural distortion with respect to particle size and destroying the spiral spin structure, which plays the vital role in high-performance applications. In this investigation, multifunctional single phase Bi1-xLaxFe1-yCoyO3 nanomaterials were synthesized by co-precipitation technique. The chemical composition, phase genesis, morphology and thermal characteristics of the Bi1-xLaxFe1-yCoyO3 were studied by FTIR, XRD, SEM/EDS, TEM and TGA. XRD studies confirmed single phase distorted rhombohedral structure in Bi1-xLaxFe1-yCoyO3. The novelty in magnetic behavior of the Bi0.85La0.15Fe0.75Co0.25O3 multiferroic at room temperature showed both ferro and anti-ferromagnetic nature with higher order remanent magnetization among other nanocomposites in this study. This magnetic anomaly in Bi0.85La0.15Fe0.75Co0.25O3 is due to doping and size effects on the crystal structure that leads to spin-orbit interactions. Besides, Bi0.85La0.15Fe0.75Co0.25O3 integrated graphene oxide (GO) nanocomposite has shown the change in the magnetic hysteresis that indicates the effect of the semiconducting behavior of GO on the ordered magnetic moments in the multiferroic. This kind of magnetic anomaly could form advanced multiferroic devices.

  6. Low gravity on earth by magnetic levitation of biological material.

    Science.gov (United States)

    Valles, James M; Guevorkian, Karine

    2002-07-01

    The use of a magnetic field gradient levitation apparatus as a tool for investigating gravisensing mechanisms in biological systems and as a low gravity simulator for biological systems is described. The basic principles are described. Differences between its application to pure materials and the heterogeneous materials of biological materials are emphasized.

  7. Annual Conference on Magnetism and Magnetic Materials, 29th, Pittsburgh, PA, November 8-11, 1983, Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, R.; Koon, N.C.; Cooper, B.R.

    1984-03-15

    Various topics on magnetism and magnetic materials are addressed. The subjects considered include: spin glasses, amorphous magnetism, actinide and rare earth intermetallics, magnetic excitation, itinerant magnetism and magnetic structure, valence instabilities, Kondo effect, transport and Hall effects, mixed valence and Kondo compounds, superconductivity and magnetism, d and f electron magnetism and superconductivity, Fe-based microcrystalline and permanent magnetic alloys, hard and soft magnetic materials, and magnetooptics. Also discussed are: numerical methods for magnetic field computation, recording theory and experiments, recording heads and media, magnetic studies via hyperfine interactions, magnetic semiconductors, magnet insulators, transition metal systems, random fields, critical phenomena and magnetoelastic effects and resonance, surfaces and interfaces, magnetostatic waves and resonance, bubble materials and implantation, bubble devices and physics, magnetic separation, ferrofluids, magnetochemistry, new techniques and materials, and new applications.

  8. Annual Conference on Magnetism and Magnetic Materials, 29th, Pittsburgh, PA, November 8-11, 1983, Proceedings

    Science.gov (United States)

    Hasegawa, R.; Koon, N. C.; Cooper, B. R.

    1984-03-01

    Various topics on magnetism and magnetic materials are addressed. The subjects considered include: spin glasses, amorphous magnetism, actinide and rare earth intermetallics, magnetic excitation, itinerant magnetism and magnetic structure, valence instabilities, Kondo effect, transport and Hall effects, mixed valence and Kondo compounds, superconductivity and magnetism, d and f electron magnetism and superconductivity, Fe-based microcrystalline and permanent magnetic alloys, hard and soft magnetic materials, and magnetooptics. Also discussed are: numerical methods for magnetic field computation, recording theory and experiments, recording heads and media, magnetic studies via hyperfine interactions, magnetic semiconductors, magnet insulators, transition metal systems, random fields, critical phenomena and magnetoelastic effects and resonance, surfaces and interfaces, magnetostatic waves and resonance, bubble materials and implantation, bubble devices and physics, magnetic separation, ferrofluids, magnetochemistry, new techniques and materials, and new applications. For individual items see A84-27016 to A84-27043

  9. Replacing critical rare earth materials in high energy density magnets

    Science.gov (United States)

    McCallum, R. William

    2012-02-01

    High energy density permanent magnets are crucial to the design of internal permanent magnet motors (IPM) for hybride and electric vehicles and direct drive wind generators. Current motor designs use rare earth permanent magnets which easily meet the performance goals, however, the rising concerns over cost and foreign control of the current supply of rare earth resources has motivated a search for non-rare earth based permanent magnets alloys with performance metrics which allow the design of permanent magnet motors and generators without rare earth magnets. This talk will discuss the state of non-rare-earth permanent magnets and efforts to both improve the current materials and find new materials. These efforts combine first principles calculations and meso-scale magnetic modeling with advance characterization and synthesis techniques in order to advance the state of the art in non rare earth permanent magnets. The use of genetic algorithms in first principle structural calculations, combinatorial synthesis in the experimental search for materials, atom probe microscopy to characterize grain boundaries on the atomic level, and other state of the art techniques will be discussed. In addition the possibility of replacing critical rare earth elements with the most abundant rare earth Ce will be discussed.

  10. Inertial and magnetic sensing of human movement near ferromagnetic materials

    NARCIS (Netherlands)

    Roetenberg, D.; Luinge, Hendrik J.; Veltink, Petrus H.

    2003-01-01

    This paper describes a Kalman filter design to estimate orientation of human body segments by fusing gyroscope, accelerometer and magnetometer signals. Ferromagnetic materials near the sensor disturb the local magnetic field and therefore the orientation estimation. The magnetic disturbance can be

  11. Ansys Analysis of Weakly Magnetic Materials in MR Tomography

    Directory of Open Access Journals (Sweden)

    Miroslav Steinbauer

    2004-01-01

    Full Text Available The paper deals with the impact of weakly magnetic materials on magnetic field in MR tomography. The resultsobtained by finite element method modelling as well as data measured by MR tomography are introduced. Method ofmagnetic susceptibility determination using MRI is discussed.

  12. Introduction to Frustrated Magnetism Materials, Experiments, Theory

    CERN Document Server

    Lacroix, Claudine; Mila, Frédéric

    2011-01-01

    The field of Highly Frustrated Magnetism has developed and expanded considerably over the last 15 years. Originating with canonical geometric frustration of interactions, it today extends over other phenomena with many degrees of freedom, including magneto-elastic couplings, orbital degrees of freedom, dilution effects, and electron doping. It is also demonstrated that the concept of frustration impacts many other fields in physics beyond magnetism. This book represents a state-of-the-art review aimed at a broad audience with tutorial chapters and more topical ones, which encompass solid-state chemistry as well as experimental and theoretical physics.

  13. Advanced Electric and Magnetic Material Models for FDTD Electromagnetic Codes

    CERN Document Server

    Poole, Brian R; Nelson, Scott D

    2005-01-01

    The modeling of dielectric and magnetic materials in the time domain is required for pulse power applications, pulsed induction accelerators, and advanced transmission lines. For example, most induction accelerator modules require the use of magnetic materials to provide adequate Volt-sec during the acceleration pulse. These models require hysteresis and saturation to simulate the saturation wavefront in a multipulse environment. In high voltage transmission line applications such as shock or soliton lines the dielectric is operating in a highly nonlinear regime, which requires nonlinear models. Simple 1-D models are developed for fast parameterization of transmission line structures. In the case of nonlinear dielectrics, a simple analytic model describing the permittivity in terms of electric field is used in a 3-D finite difference time domain code (FDTD). In the case of magnetic materials, both rate independent and rate dependent Hodgdon magnetic material models have been implemented into 3-D FDTD codes an...

  14. ADVANCED ELECTRIC AND MAGNETIC MATERIAL MODELS FOR FDTD ELECTROMAGNETIC CODES

    Energy Technology Data Exchange (ETDEWEB)

    Poole, B R; Nelson, S D; Langdon, S

    2005-05-05

    The modeling of dielectric and magnetic materials in the time domain is required for pulse power applications, pulsed induction accelerators, and advanced transmission lines. For example, most induction accelerator modules require the use of magnetic materials to provide adequate Volt-sec during the acceleration pulse. These models require hysteresis and saturation to simulate the saturation wavefront in a multipulse environment. In high voltage transmission line applications such as shock or soliton lines the dielectric is operating in a highly nonlinear regime, which require nonlinear models. Simple 1-D models are developed for fast parameterization of transmission line structures. In the case of nonlinear dielectrics, a simple analytic model describing the permittivity in terms of electric field is used in a 3-D finite difference time domain code (FDTD). In the case of magnetic materials, both rate independent and rate dependent Hodgdon magnetic material models have been implemented into 3-D FDTD codes and 1-D codes.

  15. FMR measurements in fire ants: evidence of magnetic material

    Energy Technology Data Exchange (ETDEWEB)

    Esquivel, Darci M.S.; Acosta-Avalos, Daniel; El-Jaick, Lea J.; Cunha, Alexandra D.M.; Malheiros, Maria G.; Wajnberg, Eliane [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Linhares, Marilia P. [Centro de Ciencias do Estado, do Rio de Janeiro, Rio de Janeiro, RJ (Brazil)

    1998-01-01

    Based on the behavioral and the localization of iron-containing tissue fire ants were examined by EPR for magnetic material. Results suggest the presence of magnetite particles. (author) 12 refs., 1 fig.

  16. Final Report: Nanoscale Dynamical Heterogeneity in Complex Magnetic Materials

    Energy Technology Data Exchange (ETDEWEB)

    Kevan, Stephen [Univ. of Oregon, Eugene, OR (United States)

    2016-05-27

    A magnetic object can be demagnetized by dropping it on a hard surface, but what does ‘demagnetized’ actually mean? In 1919 Heinrich Barkhausen proved the existence of magnetic domains, which are regions of uniform magnetization that are much larger than atoms but much smaller than a macroscopic object. A material is fully magnetized when domain magnetizations are aligned, while it is demagnetized when the domain magnetizations are randomly oriented and the net magnetization is zero. The heterogeneity of a demagnetized object leads to interesting questions. Magnets are unstable when their poles align, and stable when their poles anti-align, so why is the magnetized state ever stable? What do domains look like? What is the structure of a domain wall? How does the magnetized state transform to the demagnetized state? How do domains appear and disappear? What are the statistical properties of domains and how do these vary as the domain pattern evolves? Some of these questions remain the focus of intense study nearly a century after Barkhausen’s discovery. For example, just a few years ago a new kind of magnetic texture called a skyrmion was discovered. A skyrmion is a magnetic domain that is a nanometer-scale, topologically protected vortex. ‘Topologically protected’ means that skyrmions are hard to destroy and so are stable for extended periods. Skyrmions are characterized by integral quantum numbers and are observed to move with little dissipation and so could store and process information with very low power input. Our research project uses soft x-rays, which offer very high magnetic contrast, to probe magnetic heterogeneity and to measure how it evolves in time under external influences. We will condition a soft x-ray beam so that the wave fronts will be coherent, that is, they will be smooth and well-defined. When coherent soft x-ray beam interacts with a magnetic material, the magnetic heterogeneity is imprinted onto the wave fronts and projected into

  17. Magnetic properties measurement of soft magnetic composite material (SOMALOY 700) by using 3-D tester

    Science.gov (United States)

    Asari, Ashraf; Guo, Youguang; Zhu, Jianguo

    2017-08-01

    Core losses of rotating electrical machine can be predicted by identifying the magnetic properties of the magnetic material. The magnetic properties should be properly measured since there are some variations of vector flux density in the rotating machine. In this paper, the SOMALOY 700 material has been measured under x, y and z- axes flux density penetration by using the 3-D tester. The calibrated sensing coils are used in detecting the flux densities which have been generated by the Labview software. The measured sensing voltages are used in obtaining the magnetic properties of the sample such as magnetic flux density B, magnetic field strength H, hysteresis loop which can be used to calculate the total core loss of the sample. The results of the measurement are analyzed by using the Mathcad software before being compared to another material.

  18. Digital lock-in detection of site-specific magnetism in magnetic materials

    Science.gov (United States)

    Haskel, Daniel [Naperville, IL; Lang, Jonathan C [Naperville, IL; Srajer, George [Oak Park, IL

    2008-07-22

    The polarization and diffraction characteristics of x-rays incident upon a magnetic material are manipulated to provide a desired magnetic sensitivity in the material. The contrast in diffracted intensity of opposite helicities of circularly polarized x-rays is measured to permit separation of magnetic signals by element type and by atomic environment. This allows for the direct probing of magnetic signals from elements of the same species in nonequivalent atomic environments to better understand the behavior and characteristics of permanent magnetic materials. By using known crystallographic information together with manipulation of the polarization of x-rays having energies tuned near element-specific electronic excitations and by detecting and comparing the incident and diffracted photons at the same frequency, more accurate magnetic measurements can be made over shorter observation periods.

  19. Static magnetic field concentration and enhancement using magnetic materials with positive permeability

    CERN Document Server

    Sun, F

    2013-01-01

    In this paper a novel compressor for static magnetic fields is proposed based on finite embedded transformation optics. When the DC magnetic field passes through the designed device, the magnetic field can be compressed inside the device. After it passes through the device, one can obtain an enhanced static magnetic field behind the output surface of the device (in a free space region). We can also combine our compressor with some other structures to get a higher static magnetic field enhancement in a free space region. In contrast with other devices based on transformation optics for enhancing static magnetic fields, our device is not a closed structure and thus has some special applications (e.g., for controlling magnetic nano-particles for gene and drag delivery). The designed compressor can be constructed by using currently available materials or DC meta-materials with positive permeability. Numerical simulation verifies good performance of our device.

  20. Magnetic materials in Japan research, applications and potential

    CERN Document Server

    2013-01-01

    Please note this is a Short Discount publication. This, the third report in Elsevier's Materials Technology in Japan series, concentrates on magnetic materials as a topic gaining worldwide attention, and each chapter looks not only at current research, but also describes the technology as it is being applied and its future potential. Magnetic-related research is the second largest field of research in Japan after semiconductors, with the estimated number of researchers and engineers engaged in magnetics-related activities currently at 20,000. This research report serves as both a review of

  1. Non-destructive magnetic adaptive testing of ferromagnetic materials

    Science.gov (United States)

    Tomás̆, I.

    2004-01-01

    A simple way of measuring and processing of magnetic parameters, intended to optimize their ability to reflect mechanical and structural alterations of ferromagnetic materials is described here. The method is adaptive with respect to the investigated material and to the investigated structural alterations of the sample, as it always utilizes that particular range of the measured data, that is the most sensitive to the explored material and to its explored structural change. The optimum elements of the suitably defined matrices of the magnetic variables, based on the measurement of families of minor hysteresis loops, are more sensitive than any of the traditional parameters obtained from the saturation-to-saturation loop. In order to get the optimum elements, the samples do not have to be measured up to their saturation value, but to a pre-determined lower magnetization value only. The method is illustrated on magnetic reflection of plastic deformation of a construction steel sample.

  2. Magnetic Sensors Based on Amorphous Ferromagnetic Materials: A Review.

    Science.gov (United States)

    Morón, Carlos; Cabrera, Carolina; Morón, Alberto; García, Alfonso; González, Mercedes

    2015-11-11

    Currently there are many types of sensors that are used in lots of applications. Among these, magnetic sensors are a good alternative for the detection and measurement of different phenomena because they are a "simple" and readily available technology. For the construction of such devices there are many magnetic materials available, although amorphous ferromagnetic materials are the most suitable. The existence in the market of these materials allows the production of different kinds of sensors, without requiring expensive manufacture investments for the magnetic cores. Furthermore, these are not fragile materials that require special care, favouring the construction of solid and reliable devices. Another important feature is that these sensors can be developed without electric contact between the measuring device and the sensor, making them especially fit for use in harsh environments. In this review we will look at the main types of developed magnetic sensors. This work presents the state of the art of magnetic sensors based on amorphous ferromagnetic materials used in modern technology: security devices, weapon detection, magnetic maps, car industry, credit cards, etc.

  3. Magnetic Sensors Based on Amorphous Ferromagnetic Materials: A Review

    Directory of Open Access Journals (Sweden)

    Carlos Morón

    2015-11-01

    Full Text Available Currently there are many types of sensors that are used in lots of applications. Among these, magnetic sensors are a good alternative for the detection and measurement of different phenomena because they are a “simple” and readily available technology. For the construction of such devices there are many magnetic materials available, although amorphous ferromagnetic materials are the most suitable. The existence in the market of these materials allows the production of different kinds of sensors, without requiring expensive manufacture investments for the magnetic cores. Furthermore, these are not fragile materials that require special care, favouring the construction of solid and reliable devices. Another important feature is that these sensors can be developed without electric contact between the measuring device and the sensor, making them especially fit for use in harsh environments. In this review we will look at the main types of developed magnetic sensors. This work presents the state of the art of magnetic sensors based on amorphous ferromagnetic materials used in modern technology: security devices, weapon detection, magnetic maps, car industry, credit cards, etc.

  4. Magnetic Sensors Based on Amorphous Ferromagnetic Materials: A Review

    Science.gov (United States)

    Morón, Carlos; Cabrera, Carolina; Morón, Alberto; García, Alfonso; González, Mercedes

    2015-01-01

    Currently there are many types of sensors that are used in lots of applications. Among these, magnetic sensors are a good alternative for the detection and measurement of different phenomena because they are a “simple” and readily available technology. For the construction of such devices there are many magnetic materials available, although amorphous ferromagnetic materials are the most suitable. The existence in the market of these materials allows the production of different kinds of sensors, without requiring expensive manufacture investments for the magnetic cores. Furthermore, these are not fragile materials that require special care, favouring the construction of solid and reliable devices. Another important feature is that these sensors can be developed without electric contact between the measuring device and the sensor, making them especially fit for use in harsh environments. In this review we will look at the main types of developed magnetic sensors. This work presents the state of the art of magnetic sensors based on amorphous ferromagnetic materials used in modern technology: security devices, weapon detection, magnetic maps, car industry, credit cards, etc. PMID:26569244

  5. Magnetic Properties of Nanoparticles of Antiferromagnetic Materials

    DEFF Research Database (Denmark)

    Mørup, Steen; Frandsen, Cathrine; Bødker, Franz

    2003-01-01

    The magnetic properties of antiferromagnetic nanoparticles have been studied by Mossbauer spectroscopy and neutron scattering. Temperature series of Mossbauer spectra of non-interacting, superparamagnetic hematite nanoparticles were fitted by use of the Blume-Tjon relaxation model. It has been...... of the parameters obtained from Mossbauer spectroscopy and neutron scattering. In samples of interacting hematite nanoparticles, the relaxation was significantly suppressed. The Mossbauer data for these samples are in accordance with a mean field model for an ordered state of strongly interacting particles. Mixing...... nanoparticles of hematite with CoO nanoparticles resulted in suppression of the superparamagnetic relaxation, whereas NiO nanoparticles had the opposite effect....

  6. Magnetic preferential orientation of metal oxide superconducting materials

    Science.gov (United States)

    Capone, Donald W.; Dunlap, Bobby D.; Veal, Boyd W.

    1990-01-01

    A superconductor comprised of a polycrystalline metal oxide such as YBa.sub.2 Cu.sub.3 O.sub.7-X (where 0material permits the use of an applied magnetic field to orient the individual crystals when in the superconducting state to substantially increase current transport between adjacent grains. In another embodiment, the anisotropic paramagnetic susceptibility of rare-earth ions substituted into the oxide material is made use of as an applied magnetic field orients the particles in a preferential direction. This latter operation can be performed with the material in the normal (non-superconducting) state.

  7. Multimaterial magnetically assisted 3D printing of composite materials

    Science.gov (United States)

    Kokkinis, Dimitri; Schaffner, Manuel; Studart, André R.

    2015-10-01

    3D printing has become commonplace for the manufacturing of objects with unusual geometries. Recent developments that enabled printing of multiple materials indicate that the technology can potentially offer a much wider design space beyond unusual shaping. Here we show that a new dimension in this design space can be exploited through the control of the orientation of anisotropic particles used as building blocks during a direct ink-writing process. Particle orientation control is demonstrated by applying low magnetic fields on deposited inks pre-loaded with magnetized stiff platelets. Multimaterial dispensers and a two-component mixing unit provide additional control over the local composition of the printed material. The five-dimensional design space covered by the proposed multimaterial magnetically assisted 3D printing platform (MM-3D printing) opens the way towards the manufacturing of functional heterogeneous materials with exquisite microstructural features thus far only accessible by biological materials grown in nature.

  8. Multimaterial magnetically assisted 3D printing of composite materials

    Science.gov (United States)

    Kokkinis, Dimitri; Schaffner, Manuel; Studart, André R.

    2015-01-01

    3D printing has become commonplace for the manufacturing of objects with unusual geometries. Recent developments that enabled printing of multiple materials indicate that the technology can potentially offer a much wider design space beyond unusual shaping. Here we show that a new dimension in this design space can be exploited through the control of the orientation of anisotropic particles used as building blocks during a direct ink-writing process. Particle orientation control is demonstrated by applying low magnetic fields on deposited inks pre-loaded with magnetized stiff platelets. Multimaterial dispensers and a two-component mixing unit provide additional control over the local composition of the printed material. The five-dimensional design space covered by the proposed multimaterial magnetically assisted 3D printing platform (MM-3D printing) opens the way towards the manufacturing of functional heterogeneous materials with exquisite microstructural features thus far only accessible by biological materials grown in nature. PMID:26494528

  9. Magnetic resonance imaging of granular materials

    Science.gov (United States)

    Stannarius, Ralf

    2017-05-01

    Magnetic Resonance Imaging (MRI) has become one of the most important tools to screen humans in medicine; virtually every modern hospital is equipped with a Nuclear Magnetic Resonance (NMR) tomograph. The potential of NMR in 3D imaging tasks is by far greater, but there is only "a handful" of MRI studies of particulate matter. The method is expensive, time-consuming, and requires a deep understanding of pulse sequences, signal acquisition, and processing. We give a short introduction into the physical principles of this imaging technique, describe its advantages and limitations for the screening of granular matter, and present a number of examples of different application purposes, from the exploration of granular packing, via the detection of flow and particle diffusion, to real dynamic measurements. Probably, X-ray computed tomography is preferable in most applications, but fast imaging of single slices with modern MRI techniques is unmatched, and the additional opportunity to retrieve spatially resolved flow and diffusion profiles without particle tracking is a unique feature.

  10. Investigation of the magnetic properties of soft magnetic materials using LabVIEW

    Energy Technology Data Exchange (ETDEWEB)

    Nafalski, A.; Goel, O.E. [Flinders Univ. of South Australia, Bedford Park, SA (Australia); Kundu, A. [Northern Territory Univ., Casuarina, NT (Australia)

    1995-12-31

    Magnetic properties of soft magnetic materials are crucially important in the operation of electromagnetic devices. Traditional methods of determining these properties have involved tedious and time consuming manual measurements. Use of computers has provided means of accelerating the measurement and ensuring greater measurement accuracy. The merging visual and graphical programming languages based on the concept of `virtual instrument` are now enabling the measurement of systems to be much more user-friendly in addition to a number of further benefits. Virtual instrumentation offers significant advantages in implementing a measurement system for the investigation of magnetic properties of soft magnetic materials. This paper describes LabVIEW, a proprietary graphical programming language used in the development of computer-aided techniques for measuring magnetic properties of materials. The software is considered to be versatile and flexible, and has the advantage of reducing the cost of dedicated instrumentation hardware. (author). 6 figs., 3 refs.

  11. Models and materials for generalized Kitaev magnetism

    Science.gov (United States)

    Winter, Stephen M.; Tsirlin, Alexander A.; Daghofer, Maria; van den Brink, Jeroen; Singh, Yogesh; Gegenwart, Philipp; Valentí, Roser

    2017-12-01

    The exactly solvable Kitaev model on the honeycomb lattice has recently received enormous attention linked to the hope of achieving novel spin-liquid states with fractionalized Majorana-like excitations. In this review, we analyze the mechanism proposed by Jackeli and Khaliullin to identify Kitaev materials based on spin-orbital dependent bond interactions and provide a comprehensive overview of its implications in real materials. We set the focus on experimental results and current theoretical understanding of planar honeycomb systems (Na2IrO3, α-Li2IrO3, and α-RuCl3), three-dimensional Kitaev materials (β- and γ-Li2IrO3), and other potential candidates, completing the review with the list of open questions awaiting new insights.

  12. Structure and magnetism in novel group IV element-based magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Tsui, Frank [Univ. of North Carolina, Chapel Hill, NC (United States)

    2013-08-14

    The project is to investigate structure, magnetism and spin dependent states of novel group IV element-based magnetic thin films and heterostructures as a function of composition and epitaxial constraints. The materials systems of interest are Si-compatible epitaxial films and heterostructures of Si/Ge-based magnetic ternary alloys grown by non-equilibrium molecular beam epitaxy (MBE) techniques, specifically doped magnetic semiconductors (DMS) and half-metallic Heusler alloys. Systematic structural, chemical, magnetic, and electrical measurements are carried out, using x-ray microbeam techniques, magnetotunneling spectroscopy and microscopy, and magnetotransport. The work is aimed at elucidating the nature and interplay between structure, chemical order, magnetism, and spin-dependent states in these novel materials, at developing materials and techniques to realize and control fully spin polarized states, and at exploring fundamental processes that stabilize the epitaxial magnetic nanostructures and control the electronic and magnetic states in these complex materials. Combinatorial approach provides the means for the systematic studies, and the complex nature of the work necessitates this approach.

  13. Magnetic actuation of thick film multi-material compliant mechanisms

    Science.gov (United States)

    Vogtmann, Dana; St. Pierre, Ryan; Bergbreiter, Sarah

    2017-12-01

    This work presents models and experimental validation of magnetically actuated silicon mechanisms with elastomer hinges. Combining both highly compliant hinges and magnetic actuation results in mechanisms that can be actuated with large torques, large displacements, and high power. A single link mechanism is modeled, fabricated, and tested as a proof-of-concept device for this approach. The fabricated elastomer used in this work is characterized for its static and dynamic properties, and the dipoles of the magnetic materials used are also characterized. Using these measured material properties, the modeled behavior of the single link mechanism is then compared to experimental results in both static and dynamic tests. The resulting link can be statically actuated over 150° (75.1° in both directions) with a maximum applied power from the magnetic field of 0.70 mW at resonance.

  14. Magnetic Nanostructures Patterned by Self-Organized Materials

    Science.gov (United States)

    2016-01-05

    and Monte-Carlo simulations, using commercial codes and our own codes. In thin films , we have been working on the control of magnetic anisotropy in...parent continuous film , which depends on the hole size introduced in the Co thin film . This effect is related to the reversibility of the magnetic...materials and interfaces; domain wall dynamics; and inter-element interactions. There are fundamental questions in these topics that we addressed, such as

  15. Numerical Modeling of Multi-Material Active Magnetic Regeneration

    DEFF Research Database (Denmark)

    Nielsen, Kaspar Kirstein; Engelbrecht, Kurt; Bahl, Christian Robert Haffenden

    2009-01-01

    and the specific heat as a function of temperature at constant magnetic field. A 2.5-dimensional numerical model of an active magnetic regenerative (AMR) refrigerator device is presented. The experimental AMR located at Risø DTU has been equipped with a parallel-plate based regenerator made of the two materials......Magnetic refrigeration is a potentially environmentally-friendly alternative to vapour compression technology that is presented in this paper. The magnetocaloric effect in two magnetocaloric compounds in the La(Fe,Co,Si)13 series is presented in terms of their adiabatic temperature change...

  16. Towards Magnetic Carbo-meric Molecular Materials.

    Science.gov (United States)

    Poidevin, Corentin; Malrieu, Jean-Paul; Trinquier, Georges; Lepetit, Christine; Allouti, Faycal; Alikhani, M Esmail; Chauvin, Remi

    2016-04-04

    Numerous studies have underlined the putative diradical character of π-conjugated molecules that can be described by closed-shell Lewis structures, for instance, p-dimethylene p-n phenylenes, or long polyacenes. In the latter compounds, the only way to save the aromaticity of the six-membered rings is to give up the Lewis electron pairing in the singlet biradical ground state. The present work considers the possibility of doing the same by using the basic C2 units of carbo-meric architectures. A series of acyclic and cyclic carbo-meric architectures is studied by using UB3LYP DFT broken-symmetry calculations, including spin decontaminations and subsequent geometry optimization of the singlet diradical. The C2 units are shown to stabilize the singlet biradical by spin delocalization, two of them playing approximately the same role as one radical-insulating 1,4 phenylene moiety. The results are generalized to the investigation of open-shell polyradical singlet states of rigid hydrocarbon structures, the symmetry and rigidity of which can assist cooperativity and self spin polarization effect. Several synthesis targets with challenging magnetic/spin properties are suggested in the carbo-mer series. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Tessellated permanent magnet circuits for flow-through, open gradient separations of weakly magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Lee R. [Department of Biomedical Engineering, Cleveland Clinic, 9500 Euclid Ave., Cleveland OH 44195 (United States); Williams, P. Stephen [Cambrian Technologies, Inc., Cleveland, OH (United States); Chalmers, Jeffrey J. [William G. Lowrie Department of Chemical and Biomedical Engineering, The Ohio State University, Columbus 151 W. Woodruff Avenue, OH 43210 (United States); Zborowski, Maciej, E-mail: zborowm@ccf.org [Department of Biomedical Engineering, Cleveland Clinic, 9500 Euclid Ave., Cleveland OH 44195 (United States)

    2017-04-01

    Emerging microfluidic-based cell assays favor label-free red blood cell (RBC) depletion. Magnetic separation of RBC is possible because of the paramagnetism of deoxygenated hemoglobin but the process is slow for open-gradient field configurations. In order to increase the throughput, periodic arrangements of the unit magnets were considered, consisting of commercially available Nd-Fe-B permanent magnets and soft steel flux return pieces. The magnet design is uniquely suitable for multiplexing by magnet tessellation, here meaning the tiling of the magnet assembly cross-sectional plane by periodic repetition of the magnet and the flow channel shapes. The periodic pattern of magnet magnetizations allows a reduction of the magnetic material per channel with minimal distortion of the field cylindrical symmetry inside the magnet apertures. A number of such magnet patterns are investigated for separator performance, size and economy with the goal of designing an open-gradient magnetic separator capable of reducing the RBC number concentration a hundred-fold in 1 mL whole blood per hour. - Highlights: • Simple geometry of commercial, off-the-shelf NdFeB magnet blocks is amenable to generate high fields and open gradients. • Periodic pattern of permanent magnet blocks (tessellation) reduces the number of blocks per separation channel and improves the efficiency of separator design. • Split-flow lateral transport thin (SPLITT) fractionation model predicts 100-fold reduction of red blood cells from 1 mL whole blood sample in 1 h, suitable for laboratory medicine applications.

  18. Dynamic material strength measurement utilizing magnetically applied pressure-shear

    Directory of Open Access Journals (Sweden)

    Alexander C.S.

    2012-08-01

    Full Text Available Magnetically applied pressure-shear (MAPS is a recently developed technique used to measure dynamic material strength developed at Sandia National Laboratories utilizing magneto-hydrodynamic (MHD drive pulsed power systems. MHD drive platforms generate high pressures by passing a large current through a pair of parallel plate conductors which, in essence, form a single turn magnet coil. Lorentz forces resulting from the interaction of the self-generated magnetic field and the drive current repel the plates and result in a high pressure ramp wave propagating in the conductors. This is the principle by which the Sandia Z Machine operates for dynamic material testing. MAPS relies on the addition of a second, external magnetic field applied orthogonally to both the drive current and the self-generated magnetic field. The interaction of the drive current and this external field results in a shear wave being induced directly in the conductors. Thus both longitudinal and shear stresses are generated. These stresses are coupled to a sample material of interest where shear strength is probed by determining the maximum transmissible shear stress in the state defined by the longitudinal compression. Both longitudinal and transverse velocities are measured via a specialized velocity interferometer system for any reflector (VISAR. Pressure and shear strength of the sample are calculated directly from the VISAR data. Results of tests on several materials at modest pressures (∼10GPa will be presented and discussed.

  19. Dynamic material strength measurement utilizing magnetically applied pressure-shear

    Science.gov (United States)

    Alexander, C. S.

    2012-08-01

    Magnetically applied pressure-shear (MAPS) is a recently developed technique used to measure dynamic material strength developed at Sandia National Laboratories utilizing magneto-hydrodynamic (MHD) drive pulsed power systems. MHD drive platforms generate high pressures by passing a large current through a pair of parallel plate conductors which, in essence, form a single turn magnet coil. Lorentz forces resulting from the interaction of the self-generated magnetic field and the drive current repel the plates and result in a high pressure ramp wave propagating in the conductors. This is the principle by which the Sandia Z Machine operates for dynamic material testing. MAPS relies on the addition of a second, external magnetic field applied orthogonally to both the drive current and the self-generated magnetic field. The interaction of the drive current and this external field results in a shear wave being induced directly in the conductors. Thus both longitudinal and shear stresses are generated. These stresses are coupled to a sample material of interest where shear strength is probed by determining the maximum transmissible shear stress in the state defined by the longitudinal compression. Both longitudinal and transverse velocities are measured via a specialized velocity interferometer system for any reflector (VISAR). Pressure and shear strength of the sample are calculated directly from the VISAR data. Results of tests on several materials at modest pressures (˜10GPa) will be presented and discussed.

  20. Exploring Magnetic Elastocaloric Materials for Solid-State Cooling

    Science.gov (United States)

    Liu, Jian; Zhao, Dewei; Li, Yang

    2017-08-01

    In the past decade, there has been an increased surge in the research on elastocaloric materials for solid-state refrigerators. The strong coupling between structure and magnetism inspires the discovery of new multi-field driven elastocaloric alloys. This work is devoted to magnetic shape memory alloys suitable for mechanical cooling applications. Some novel characteristics in magnetostructural transition materials other than conventional shape memory alloys are overviewed. From the physical and engineering points of view, we have put forward general strategies to maximize elastocaloric temperature change to increase performance reversibility and to improve mechanical properties. The barocaloric effect as a sister-cooling alternative is also discussed.

  1. Exploring Magnetic Elastocaloric Materials for Solid-State Cooling

    Science.gov (United States)

    Liu, Jian; Zhao, Dewei; Li, Yang

    2017-09-01

    In the past decade, there has been an increased surge in the research on elastocaloric materials for solid-state refrigerators. The strong coupling between structure and magnetism inspires the discovery of new multi-field driven elastocaloric alloys. This work is devoted to magnetic shape memory alloys suitable for mechanical cooling applications. Some novel characteristics in magnetostructural transition materials other than conventional shape memory alloys are overviewed. From the physical and engineering points of view, we have put forward general strategies to maximize elastocaloric temperature change to increase performance reversibility and to improve mechanical properties. The barocaloric effect as a sister-cooling alternative is also discussed.

  2. Magneto optical properties of silver doped magnetic nanocomposite material

    Directory of Open Access Journals (Sweden)

    N. Abirami

    2017-11-01

    Full Text Available Magnetic composite materials challenge traditional materials in broad applications such as transformer, sensors and electrical motors. In this work by studying the permittivity and permeability spectra of silver doped magnetic nanocomposite system, the variation of the effective refractive index with frequency is investigated for different filling factor. It is found that the value of resonance frequency decrease with filling factor. The polariton dispersion of the system is also studied. This study of the nanocomposite system can be exploited in designing modern optical devices.PACS: 75.50-y, 71.36.+c, 78.67.Sc, 78.20.Ci. Keywords: Permittivity, Permeability, Nanocomposite system, Polariton

  3. Is an Apple Magnetic: Magnetic Response of Everyday Materials Supporting Views About the Nature of Science

    Science.gov (United States)

    Laumann, Daniel

    2017-03-01

    Magnetism and its various applications are essential for our daily life and for many technological developments. The term magnetism is almost always used as a synonym for ferromagnetism. However, the magnetic properties of the elements of the periodic table indicate that the vast majority of elements are not ferromagnetic, but rather, diamagnetic or paramagnetic. Typically, only ferromagnetism is discussed in classrooms, which can create a distorted picture. This article supplies the further development of an experiment demonstrating the dia- and paramagnetic properties with an electronic balance and a neodymium magnet. It focuses on an investigation of ordinary materials that occur in pupils' everyday environment. The experiment is applicable both for a quantitative measurement of the magnetic (volume) susceptibility χV and can serve as a phenomenological approach to dia- and paramagnetism. Moreover, it encourages a discussion about typical beliefs regarding the nature of science, comparing the behavior of common objects in weak and in strong magnetic fields.

  4. Substitution effects in magnetic and superconducting materials

    Directory of Open Access Journals (Sweden)

    Peña, O.

    1999-10-01

    Full Text Available Chemical substitutions at very low level have been proved to be a very effective tool to change important physical parameters in many kinds of materials. These modifications may be the result of, for instance, subtle variations of the position of the Fermi level with respect to the density of states, presence of additional electrons which may change the hole carrier concentration, steric effects which impose contraints in the crystallographic lattice, mixed-valence states resultating from the dismutation of chemical components, etc. We review herein three systems in which the substitution effects are at the origin of new physical states : the high-Tc superconductor bismuth cuprate of the 2212 family, the mixed-valence manganese perovskites representative of giant magneto-resistive compounds, and the Chevrel phase materials in which a structural transition may inhibit the superconducting state.

    Las substituciones químicas a un nivel muy pequeño se han probado como una importante herramienta para cambiar los parámetros físicos en una gran variedad de materiales. Estas modificaciones pueden ser el resultado de, por ejemplo, muy ligeras variaciones de la posición del nivel de Fermi con respecto a la densidad de estados, presencia de electrones adicionales que pueden cambiar la concentración de portadores tipo huecos, efectos estéricos que imponen restricciones en la red cristalográfica, estados de valencia mixtos resultantes de la dismutación de los componentes químicos, etc. Aquí se revisan tres sistemas donde los efectos de substitución son el origen de nuevos estados físicos: los superconductores de alta temperatura basados en cupratos de bismuto de la familia 2212, las perovskitas de manganeso de valencia mixta representantes de compuestos con magnetorresistencia gigante, y los materiales con fases de Chevrelt cuya transición estructural puede inhibir el estado superconductor.

  5. Synthesizing and Playing with Magnetic Nanoparticles: A Comprehensive Approach to Amazing Magnetic Materials

    Science.gov (United States)

    Dalverny, Anne-Laure; Leyral, Géraldine; Rouessac, Florence; Bernaud, Laurent; Filhol, Jean-Sébastien

    2018-01-01

    Magnetic iron oxide nanoparticles were synthesized and stabilized using ammonium cations or poly(vinyl alcohol) to produce amazing materials such as safer aqueous ferrofluids, ferrogels, ferromagnetic inks, plastics, and nanopowders illustrating how versatile materials can be produced just by simple modifications. The synthesis is fast, reliable,…

  6. 2nd Latin American Workshop on Magnetism, Magnetic Materials, and Their Applications

    CERN Document Server

    Sanchez, J

    1994-01-01

    During August 24-27, 1993, approximately 60 scientists from the Americas, Europe and Japan, gathered in the city of Guanajuato, in the state of Guanajuato, Mexico, at the II Latin American Workshop on Magnetism, Magnetic Materials and their Applications. The group of scientists converging into the beautiful city of Guanajuato had come from Argentina, Chile, Brazil, Venezuela, Cuba, several places in Mexico, U. S. A. , Japan, Spain, France, Italy, Germany, Austria, Switzerland, and Denmark. The event attested to the success of the previous Workshop on Magnetism, Magnetic Materials and their Applications, held in Havana, Cuba, in 1991, as well as to the interest, level of activity and quality of the work being carried out in Latin America in the area of magnetism and magnetic materials. Equally important to everyone present was the fact that we had come to honor a friend, Professor L. M. Falicov, on his sixtieth birthday. The choice of a Latin American Workshop on magnetism as a Festschrift for Leo Falicov was,...

  7. Microstructure characterization and magnetic properties of nano structured materials

    Energy Technology Data Exchange (ETDEWEB)

    Sun, X.C

    2000-07-01

    The present thesis deals with the unique microstructural properties and their novel magnetic properties of core-shell Ni-Ce nano composite particles, carbon encapsulated Fe, Co, and Ni nanoparticles and the nano crystallization behavior of typical ferromagnetic Fe{sub 78}Si{sub 9}B{sub 13} ribbons. These properties have intensively been investigated by high resolution transmission electron microscopy (HREM), X-ray diffraction (XRD), scanning electron microscopy (Sem), X-ray energy dispersive spectroscopy [eds.]; selected area electron diffraction pattern (SAED), Ft-IR, differential scanning calorimeter (DSC). In addition, magnetic moments measurements at different temperatures and applied fields have been performed by transmission Moessbauer spectroscopy, superconducting quantum interference device magnetometer (SQUID), and vibrating sample magnetometer (VSM). The present studies may provide the insights for the better understanding of the correlation between the unique microstructure and novel magnetic properties for several magnetic nano structured materials. (Author)

  8. Determining magnetic susceptibilities of everyday materials using an electronic balance

    Science.gov (United States)

    Laumann, Daniel; Heusler, Stefan

    2017-05-01

    The magnetic properties of an object and its interaction with an external magnetic field can be described through the magnetic (volume) susceptibility χV, which divides nearly all kinds of matter into diamagnetic, paramagnetic, and ferromagnetic substances. Quantitative measurements of χV are usually technically sophisticated or require the investigation of substances with high values of χV to reveal meaningful results. Here, we show that both diamagnetic and paramagnetic effects in everyday materials can be measured using only an electronic balance and a neodymium magnet, both of which are within the reach of typical introductory college and high school physics classrooms. The experimental results match related literature values remarkably well.

  9. Effective magnetic field computation in Tokamaks in presence of magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Chiariello, Andrea G.; Formisano, Alessandro [Dip. di Ing. Industriale e dell’Informazione, Seconda Università di Napoli, Via Roma 29, I-81031 Napoli (Italy); Fresa, Raffaele [Scuola di Ingegneria, Università della Basilicata, Potenza (Italy); Consorzio EURATOM/ENEA/CREATE (Italy); Ledda, Francesco, E-mail: francesco.ledda@unina2.it [Dip. di Ing. Industriale e dell’Informazione, Seconda Università di Napoli, Via Roma 29, I-81031 Napoli (Italy); Martone, Raffaele; Pizzo, Francesco [Dip. di Ing. Industriale e dell’Informazione, Seconda Università di Napoli, Via Roma 29, I-81031 Napoli (Italy)

    2015-10-15

    Magnetic materials play an important role in the magnetic fields distribution inside Tokamaks, and their contributions must be carefully computed. In some applications, when 3D geometries are involved and high accuracy must be achieved, finite elements may reveal too computationally demanding and different approaches must be considered. In this paper, two possible solutions are presented. The first one is based on the discretization of magnetic parts into rectangular prisms with constant magnetization density; analytical formulas are then used to compute the field contribution due to each brick. The second one is based on the representation of the effect of magnetic materials as a set of dipoles, by using again analytical formulas to evaluate the contribution to the magnetic field. Iterative procedures are applied to evaluate the magnetization density in prisms. The efficiency and accuracy of both models are validated against commercial codes on a test case, and then applied to the computation of magnetic field in presence of Neutral Beam Injector in an ITER-like geometry.

  10. Magnetic mesoporous materials for removal of environmental wastes.

    Science.gov (United States)

    Kim, Byoung Chan; Lee, Jinwoo; Um, Wooyong; Kim, Jaeyun; Joo, Jin; Lee, Jin Hyung; Kwak, Ja Hun; Kim, Jae Hyun; Lee, Changha; Lee, Hongshin; Addleman, R Shane; Hyeon, Taeghwan; Gu, Man Bock; Kim, Jungbae

    2011-09-15

    We have synthesized two different magnetic mesoporous materials that can be easily separated from aqueous solutions by applying a magnetic field. Synthesized magnetic mesoporous materials, Mag-SBA-15 (magnetic ordered mesoporous silica) and Mag-OMC (magnetic ordered mesoporous carbon), have a high loading capacity of contaminants due to high surface area of the supports and high magnetic activity due to the embedded iron oxide particles. Application of surface-modified Mag-SBA-15 was investigated for the collection of mercury from water. The mercury adsorption using Mag-SBA-15 was rapid during the initial contact time and reached a steady-state condition, with an uptake of approximately 97% after 7h. Application of Mag-OMC for collection of organics from water, using fluorescein as an easily trackable model analyte, was explored. The fluorescein was absorbed into Mag-OMC within minutes and the fluorescent intensity of solution was completely disappeared after an hour. In another application, Mag-SBA-15 was used as a host of tyrosinase, and employed as recyclable catalytic scaffolds for tyrosinase-catalyzed biodegradation of catechol. Crosslinked tyrosinase in Mag-SBA-15, prepared in a two step process of tyrosinase adsorption and crosslinking, was stable enough for catechol degradation with no serious loss of enzyme activity. Considering these results of cleaning up water from toxic inorganic and organic contaminants, magnetic mesoporous materials have a great potential to be employed for the removal of environmental contaminants and potentially for the application in large-scale wastewater treatment plants. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Frustrated Magnetism and Electronic Properties of Hollandite Oxide Materials

    Science.gov (United States)

    Larson, Amber Marie

    Microporous transition metal oxides with the hollandite structure type have been prepared by standard solid-state techniques with varying compositions. With a nominal formula of Ax M8O16 and a framework of edge and corner-sharing MO6 octahedra, hollandites feature a pseudo-one dimensional tunnel occupied loosely by cation A. The metastability of these open-framework materials, combined with the ability of accommodating a variety of redox-active transition metals leads to unique and indispensable properties. Inherent to the triangular connectivity of the M cations in the hollandite framework, these materials frequently exhibit frustrated magnetic behavior. This thesis demonstrates that it is possible to significantly affect the magnetic and transport properties of these microporous materials through tuning of their chemical compositions. We have shown that it is possible to synthesize polycrystalline and single crystal hollandite materials under ambient conditions utilizing salt flux techniques. Our efforts to characterize the structure-property relationships provide some of the first magnetic structure determinations of these complex frameworks. The interesting behavior of these materials is a result of the interplay between charge, orbital, and spin degrees of freedom. This work shows that the hollandite framework is quite versatile, leading to the real possibility of tuning the material properties to achieve desired effects and opening up many potential applications for these microporous oxides.

  12. Ligand design for multidimensional magnetic materials: a metallosupramolecular perspective.

    Science.gov (United States)

    Pardo, Emilio; Ruiz-García, Rafael; Cano, Joan; Ottenwaelder, Xavier; Lescouëzec, Rodrigue; Journaux, Yves; Lloret, Francesc; Julve, Miguel

    2008-06-07

    The aim and scope of this review is to show the general validity of the 'complex-as-ligand' approach for the rational design of metallosupramolecular assemblies of increasing structural and magnetic complexity. This is illustrated herein on the basis of our recent studies on oxamato complexes with transition metal ions looking for the limits of the research avenue opened by Kahn's pioneering research twenty years ago. The use as building blocks of mono-, di- and trinuclear metal complexes with a novel family of aromatic polyoxamato ligands allowed us to move further in the coordination chemistry-based approach to high-nuclearity coordination compounds and high-dimensionality coordination polymers. In order to do so, we have taken advantage of the new developments of metallosupramolecular chemistry and in particular, of the molecular-programmed self-assembly methods that exploit the coordination preferences of metal ions and specifically tailored ligands. The judicious choice of the oxamato metal building block (substitution pattern and steric requirements of the bridging ligand, as well as the electronic configuration and magnetic anisotropy of the metal ion) allowed us to control the overall structure and magnetic properties of the final multidimensional nD products (n = 0-3). These species exhibit interesting magnetic properties which are brand-new targets in the field of molecular magnetism, such as single-molecule or single-chain magnets, and the well-known class of molecule-based magnets. This unique family of molecule-based magnetic materials expands on the reported examples of nD species with cyanide and related oxalato and dithiooxalato analogues. Moreover, the development of new oxamato metal building blocks with potential photo or redox activity at the aromatic ligand counterpart will provide us with addressable, multifunctional molecular materials for future applications in molecular electronics and nanotechnology.

  13. Magnetic characterisation of recording materials: design, instrumentation and experimental methods

    NARCIS (Netherlands)

    Samwel, E.O.

    1995-01-01

    The progress being made in the field of magnetic recording is extremely fast. The need to keep this progress going, leads to new types of recording materials which require advanced measurement systems and measurement procedures. Furthermore, the existing measurement methods need to be reviewed as

  14. Static Magnetic Properties of AL800 Garnet Material

    Energy Technology Data Exchange (ETDEWEB)

    Kuharik, J. [Fermilab; Madrak, R. [Fermilab; Makarov, A. [Fermilab; Pellico, W. [Fermilab; Sun, S. [Fermilab; Tan, C. Y. [Fermilab; Terechkine, I. [Fermilab

    2017-05-17

    A second harmonic tunable RF cavity is being devel-oped for the Fermilab Booster. This device, which prom-ises reduction of the particle beam loss at the injection, transition, and extraction stages, employs perpendicularly biased garnet material for frequency tuning. The required range of the tuning is significantly wider than in previously built and tested tunable RF devices. As a result, the mag-netic field in the garnet comes fairly close to the gyromag-netic resonance line at the lower end of the frequency range. The chosen design concept of a tuner for the cavity cannot ensure uniform magnetic field in the garnet mate-rial; thus, it is important to know the static magnetic prop-erties of the material to avoid significant increase in the lo-cal RF loss power density. This report summarizes studies performed at Fermilab to understand variations in the mag-netic properties of the AL800 garnet material used to build the tuner of the cavity.

  15. Model of the magnetization of nanocrystalline materials at low temperatures

    Science.gov (United States)

    Bian, Q.; Niewczas, M.

    2014-07-01

    A theoretical model incorporating the material texture has been developed to simulate the magnetic properties of nanocrystalline materials at low temperatures where the effect of thermal energy on magnetization is neglected. The method is based on Landau-Lifshitz-Gilbert (LLG) theory and it describes the magnetization dynamics of individual grains in the effective field. The modified LLG equation incorporates the intrinsic fields from the intragrain magnetocrystalline and grain boundary anisotropies and the interacting fields from intergrain dipolar and exchange couplings between the neighbouring grains. The model is applied to study magnetic properties of textured nanocrystalline Ni samples at 2K and is capable to reproduce closely the hysteresis loop behaviour at different orientations of applied magnetic field. Nanocrystalline Ni shows the grain boundary anisotropy constant K 1 s = - 6.0 × 104 J / m 3 and the intergrain exchange coupling denoted by the effective exchange constant Ap = 2.16 × 10-11 J/m. Analytical expressions to estimate the intergrain exchange energy density and the effective exchange constant have been formulated.

  16. Theory of neutron scattering by electrons in magnetic materials

    Science.gov (United States)

    Lovesey, S. W.

    2015-10-01

    A theory of neutron scattering by magnetic materials is reviewed with emphasis on the use of electronic multipoles that have universal appeal, because they are amenable to calculation and appear in theories of many other experimental techniques. The conventional theory of magnetic neutron scattering, which dates back to Schwinger (1937 Phys. Rev. 51 544) and Trammell (1953 Phys. Rev. 92 1387), yields an approximation for the scattering amplitude in terms of magnetic dipoles formed with the spin (S) and orbital angular momentum (L) of valence electrons. The so-called dipole-approximation has been widely adopted by researchers during the past few decades that has seen neutron scattering develop to its present status as the method of choice for investigations of magnetic structure and excitations. Looking beyond the dipole-approximation, however, reveals a wealth of additional information about electronic degrees of freedom conveniently encapsulated in magnetic multipoles. In this language, the dipole-approximation retains electronic axial dipoles, S and L. At the same level of approximation are polar dipoles—called anapoles or toroidal dipoles—allowed in the absence of a centre of inversion symmetry. Anapoles are examples of magneto-electric multipoles, time-odd and parity-odd irreducible tensors, that have come to the fore as signatures of electronic complexity in materials.

  17. Acrylamide-based magnetic nanosponges: a new smart nanocomposite material.

    Science.gov (United States)

    Bonini, Massimo; Lenz, Sebastian; Falletta, Ester; Ridi, Francesca; Carretti, Emiliano; Fratini, Emiliano; Wiedenmann, Albrecht; Baglioni, Piero

    2008-11-04

    Nanocomposite materials consisting of CoFe2O4 magnetic nanoparticles and a polyethylene glycol-acrylamide gel matrix have been synthesized. The structure of such materials was studied by means of small-angle scattering of X-rays and polarized neutrons, showing that the CoFe2O4 nanoparticles were successfully and homogeneously embedded in the gel structure. Magnetic, viscoelastic, and water retention properties of the nanocomposite gel confirm that the properties of both nanoparticles and gel are combined in the resulting nanomagnetic gel. Scanning electron microscopy highlights the nanocomposite nature of the material, showing the presence of a gel structure with different pore size distributions (pores with micron and nano-size distributions) that can be used as active sponge-like nanomagnetic container for water-based formulations as oil-in-water microemulsions.

  18. Nanomodified heat-accumulating materials controlled by a magnetic field

    Science.gov (United States)

    Shchegolkov, Alexander; Shchegolkov, Alexey; Dyachkova, Tatyana; Bodin, Nikolay; Semenov, Alexander

    2017-11-01

    The paper presents studies of nanomodified heat-accumulating materials controlled by a magnetic field. In order to obtain controlled heat-accumulating materials, synthetic motor oil CASTROL 0W30, ferromagnetic particles, CNTs and paraffin were used. Mechanically activated carbon nanotubes with ferromagnetic particles were used for the nanomodification of paraffin. Mechanoactivation ensured the production of ferromagnetic particles with an average particle size of 5 µm. Using an extrusion plant, a mixture of CNTs and ferromagnetic particles was introduced into the paraffin. Further, the nanomodified paraffin in a granular form was introduced into synthetic oil. To conduct experimental studies, a contactless method for measuring temperature was used. The thermal contact control with the help of the obtained nanomodified material is possible with a magnetic induction of 1250 mT, and a heat flux of about 74 kW/m2 is provided at the same time.

  19. Developing Antitumor Magnetic Hyperthermia: Principles, Materials and Devices.

    Science.gov (United States)

    Tishin, Alexander M; Shtil, Alexander A; Pyatakov, Alexander P; Zverev, Vladimir I

    2016-01-01

    Methods of local or loco-regional anticancer treatment are of the utmost importance because the therapeutic 'power' is applied directly to the disease site. Consequently, general toxicity is minimized. Hyperthermia, that is, a sustained increase of intratumoral temperature up to 45oC, has been investigated as a perspective treatment modality alone and/or in combination with ionizing radiation or chemotherapy. Still, the surrounding tissues can be damaged by the external heat. Development of new materials and devices gave rise to methods of inducing hyperthermia by a high frequency magnetic or electromagnetic field applied to the tumor with exogenous nanosized particles captured within it. The idea of this approach is the release of local heat in the vicinity of the magnetic nanoparticle in a time-varying magnetic field due to transfer of external magnetic field energy into the heat. Therefore, tumor cells are heated whereas the peritumoral non-malignant tissues are spared. This review analyzes recent advances in understanding physical principles that underlie magnetic hyperthermia as well as novel approaches to obtain nanoparticles with optimized physico-chemical, toxicological and tumoricidal properties. Special focus is made on the construction of devices for therapeutic purposes. The review covers recent patents and general literature sources regarding magnetic hyperthermia, the developing approach to treat otherwise intractable malignancies.

  20. [Application of magnetic materials in analysis on Chinese herb medicines].

    Science.gov (United States)

    Xu, Li-Wei; Wang, Jiu-Rong; Han, Xue-Feng

    2012-12-01

    China is the cradle of Chinese herb medicines,with rich plant resources. However, traditional processing methods have many disadvantages, such as high comsumption of organic solvent, long extraction time and high loss of effective constituents. For the purpose of rational use of Chinese herb medicines and accurate analysis on their constituents,the sample pre-treatment method with magnetic nanoparticles as the carrier brought new opportunities in recent years. after consulting literatures,the essay summarizes traditional extraction methods of Chinese herb medicines, characteristics of magnetic materials and their application in the analysis on Chinese herb medicines.

  1. Highly magnetic nanoporous carbon/iron-oxide hybrid materials.

    Science.gov (United States)

    Alam, Sher; Anand, Chokkalingam; Lakhi, Kripal Singh; Choy, Jin-Ho; Cha, Wang Soo; Elzhatry, Ahmed; Al-Deyab, Salem S; Ohya, Yutaka; Vinu, Ajayan

    2014-11-10

    The preparation of size-controllable Fe2O3 nanoparticles grown in nanoporous carbon with tuneable pore diameters is reported. These hybrid materials exhibit strong non-linear magnetic properties and a magnetic moment of approximately 229 emu g(-1), which is the highest value ever reported for nanoporous hybrids, and can be attributed to the nanosieve effect and the strong interaction between the nanoparticles and the carbon walls. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Symposium Q: Magnetic Thin Films, Heterostructures, and Device Materials

    Science.gov (United States)

    2007-05-22

    001)/-y - Manganese (001)Bilayers. Harm Wieldraaijer, Wim J.M. de Jonge and Juergen T Kohlhepp; Applied Physics, 11:30 AM Q4.8 Eindhoven University of...on the BiFeO 3 film, implying an antiferromagnetic-ferroelectric coupling iq this material. This work is supported by an ONR-MURI and a LBL-LDRD...with evidence of manganese is observed for all samples, consistent with tunneling between a metal induced magnetism3. Through magnetic and structural

  3. Analysis of ringing due to magnetic core materials used in pulsed nuclear magnetic resonance applications

    Science.gov (United States)

    Prabhu Gaunkar, Neelam; Nlebedim, Cajetan; Hadimani, Ravi; Bulu, Irfan; Song, Yi-Qiao; Mina, Mani; Jiles, David

    Oil-field well logging instruments employ pulsed nuclear magnetic resonance (NMR) techniques and use inductive sensors to detect and evaluate the presence of particular fluids in geological formations. Acting as both signal transmitters and receivers most inductive sensors employ magnetic cores to enhance the quality and amplitude of signals recorded during field measurements. It is observed that the magnetic core also responds to the applied input signal thereby generating a signal (`ringing') that interferes with the measurement of the signals from the target formations. This causes significant noise and receiver dead time and it is beneficial to eliminate/suppress the signals received from the magnetic core. In this work a detailed analysis of the magnetic core response and in particular loading of the sensor due to the presence of the magnetic core is presented. Pulsed NMR measurements over a frequency band of 100 kHz to 1MHz are used to determine the amplitude and linewidth of the signals acquired from different magnetic core materials. A lower signal amplitude and a higher linewidth are vital since these would correspond to minimal contributions from the magnetic core to the inductive sensor response and thus leading to minimized receiver dead time.

  4. Ultra-low field nuclear magnetic resonance and magnetic resonance imaging to discriminate and identify materials

    Science.gov (United States)

    Kraus, Robert H.; Matlashov, Andrei N.; Espy, Michelle A.; Volegov, Petr L.

    2010-03-30

    An ultra-low magnetic field NMR system can non-invasively examine containers. Database matching techniques can then identify hazardous materials within the containers. Ultra-low field NMR systems are ideal for this purpose because they do not require large powerful magnets and because they can examine materials enclosed in conductive shells such as lead shells. The NMR examination technique can be combined with ultra-low field NMR imaging, where an NMR image is obtained and analyzed to identify target volumes. Spatial sensitivity encoding can also be used to identify target volumes. After the target volumes are identified the NMR measurement technique can be used to identify their contents.

  5. Optimization of the magnetic properties of materials for fluxgate sensors

    Directory of Open Access Journals (Sweden)

    Luiz Carlos de Carvalho Benyosef

    2008-06-01

    Full Text Available A study was made of the variation of the magnetic properties of cobalt-based alloys using different compositions of CoFeSiB and CoFeSiBCr systems, which were produced by the melt-spinning technique and some of them subjected to a stress annealing treatment. A comparative study of core geometry and supporting material was also performed in order to obtain low noise fluxgate sensor core using amorphous magnetic ribbons of these alloys. The best alloy was a stress annealed Co67.5Fe3.5Si17.4B11.6 sample, which yielded fluxgate sensors with lower noise levels than those of commercial crystalline materials.

  6. Magnetic antiskyrmions above room temperature in tetragonal Heusler materials

    Science.gov (United States)

    Nayak, Ajaya K.; Kumar, Vivek; Ma, Tianping; Werner, Peter; Pippel, Eckhard; Sahoo, Roshnee; Damay, Franoise; Rößler, Ulrich K.; Felser, Claudia; Parkin, Stuart S. P.

    2017-08-01

    Magnetic skyrmions are topologically stable, vortex-like objects surrounded by chiral boundaries that separate a region of reversed magnetization from the surrounding magnetized material. They are closely related to nanoscopic chiral magnetic domain walls, which could be used as memory and logic elements for conventional and neuromorphic computing applications that go beyond Moore’s law. Of particular interest is ‘racetrack memory’, which is composed of vertical magnetic nanowires, each accommodating of the order of 100 domain walls, and that shows promise as a solid state, non-volatile memory with exceptional capacity and performance. Its performance is derived from the very high speeds (up to one kilometre per second) at which chiral domain walls can be moved with nanosecond current pulses in synthetic antiferromagnet racetracks. Because skyrmions are essentially composed of a pair of chiral domain walls closed in on themselves, but are, in principle, more stable to perturbations than the component domain walls themselves, they are attractive for use in spintronic applications, notably racetrack memory. Stabilization of skyrmions has generally been achieved in systems with broken inversion symmetry, in which the asymmetric Dzyaloshinskii-Moriya interaction modifies the uniform magnetic state to a swirling state. Depending on the crystal symmetry, two distinct types of skyrmions have been observed experimentally, namely, Bloch and Néel skyrmions. Here we present the experimental manifestation of another type of skyrmion—the magnetic antiskyrmion—in acentric tetragonal Heusler compounds with D2d crystal symmetry. Antiskyrmions are characterized by boundary walls that have alternating Bloch and Néel type as one traces around the boundary. A spiral magnetic ground-state, which propagates in the tetragonal basal plane, is transformed into an antiskyrmion lattice state under magnetic fields applied along the tetragonal axis over a wide range of temperatures

  7. Hybrid material as contrast agent in magnetic resonance images

    OpenAIRE

    Botella Asunción, Pablo; Cabrera García, Alejandro

    2015-01-01

    [EN] The invention relates to a contrast agent of magnetic resonance based on a hybrid material formed by an organo-metallic core derived from Prussian blue and a silica cover, and optionally, molecules of a poly(ethylene glycol), a fluorescent agent, a radio nucleus and/or a substance that directs to specific receptors, cells or tissues, joined by covalent bonding to the surface of the inorganic cover.

  8. Amorphous and Nanocrystalline High Temperature Magnetic Material for PWR

    Science.gov (United States)

    2006-03-01

    in collaboration with Magnetics, Inc. has produced nanopowders of the HITPERM materials. The work was extended to include study of...the interfacial stresses between the substrate and coating that arises during the coating processes. Alumina , Beryllia, Forsterite and Pt were...trial was performed to evaluate the efficacy of plasma synthesized ferrite coatings. NiZn ferrites were sprayed onto Alumina substrates using the

  9. Power Switches Utilizing Superconducting Material for Accelerator Magnets

    CERN Document Server

    March, S A; Yang, Y

    2009-01-01

    Power switches that utilize superconducting material find application in superconducting systems. They can be used for the protection of magnets as a replacement for warm DC breakers, as well as for the replacement of cold diodes. This paper presents a comparison of switches made of various superconducting materials having transport currents of up to 600 A and switching times of the order of milliseconds. The switches operate in the temperature range 4.2-77 K and utilize stainless steel clad YBCO tape and MgB2 tape with a nickel, copper, and iron matrix. Results from simulations and tests are reported.

  10. Giant spin Seebeck effect in a non-magnetic material.

    Science.gov (United States)

    Jaworski, C M; Myers, R C; Johnston-Halperin, E; Heremans, J P

    2012-07-11

    The spin Seebeck effect is observed when a thermal gradient applied to a spin-polarized material leads to a spatially varying transverse spin current in an adjacent non-spin-polarized material, where it gets converted into a measurable voltage. It has been previously observed with a magnitude of microvolts per kelvin in magnetically ordered materials, ferromagnetic metals, semiconductors and insulators. Here we describe a signal in a non-magnetic semiconductor (InSb) that has the hallmarks of being produced by the spin Seebeck effect, but is three orders of magnitude larger (millivolts per kelvin). We refer to the phenomenon that produces it as the giant spin Seebeck effect. Quantizing magnetic fields spin-polarize conduction electrons in semiconductors by means of Zeeman splitting, which spin-orbit coupling amplifies by a factor of ∼25 in InSb. We propose that the giant spin Seebeck effect is mediated by phonon-electron drag, which changes the electrons' momentum and directly modifies the spin-splitting energy through spin-orbit interactions. Owing to the simultaneously strong phonon-electron drag and spin-orbit coupling in InSb, the magnitude of the giant spin Seebeck voltage is comparable to the largest known classical thermopower values.

  11. The magnetic resonance force microscope: A new microscopic probe of magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Hammel, P.C.; Zhang, Z. [Los Alamos National Lab., NM (United States); Midzor, M.; Roukes, M.L. [California Inst. of Tech., Pasadena, CA (United States); Wigen, P.E. [Ohio State Univ., Columbus, OH (United States); Childress, J.R. [Univ. of Florida, Gainesville, FL (United States)

    1997-08-06

    The magnetic resonance force microscope (MRFM) marries the techniques of magnetic resonance imaging (MRI) and atomic force microscopy (AFM), to produce a three-dimensional imaging instrument with high, potentially atomic-scale, resolution. The principle of the MRFM has been successfully demonstrated in numerous experiments. By virtue of its unique capabilities the MRFM shows promise to make important contributions in fields ranging from three-dimensional materials characterization to bio-molecular structure determination. Here the authors focus on its application to the characterization and study of layered magnetic materials; the ability to illuminate the properties of buried interfaces in such materials is a particularly important goal. While sensitivity and spatial resolution are currently still far from their theoretical limits, they are nonetheless comparable to or superior to that achievable in conventional MRI. Further improvement of the MRFM will involve operation at lower temperature, application of larger field gradients, introduction of advanced mechanical resonators and improved reduction of the spurious coupling when the magnet is on the resonator.

  12. Multifunctional upconversion-magnetic hybrid nanostructured materials: synthesis and bioapplications.

    Science.gov (United States)

    Li, Xiaomin; Zhao, Dongyuan; Zhang, Fan

    2013-01-01

    The combination of nanotechnology and biology has developed into an emerging research area: nano-biotechnology. Upconversion nanoparticles (UCNPs) have attracted a great deal of attention in bioapplications due to their high chemical stability, low toxicity, and high signal-to-noise ratio. Magnetic nanoparticles (MNPs) are also well-established nanomaterials that offer controlled size, ability to be manipulated externally, and enhancement of contrast in magnetic resonance imaging (MRI). As a result, these nanoparticles could have many applications in biology and medicine, including protein purification, drug delivery, and medical imaging. Because of the potential benefits of multimodal functionality in biomedical applications, researchers would like to design and fabricate multifunctional upconversion-magnetic hybrid nanostructured materials. The hybrid nanostructures, which combine UCNPs with MNPs, exhibit upconversion fluorescence alongside superparamagnetism property. Such structures could provide a platform for enhanced bioimaging and controlled drug delivery. We expect that the combination of unique structural characteristics and integrated functions of multifunctional upconversion-magnetic nanoparticles will attract increasing research interest and could lead to new opportunities in nano-bioapplications.

  13. Multinuclear solid-state nuclear magnetic resonance of inorganic materials

    CERN Document Server

    MacKenzie, Kenneth J D

    2002-01-01

    Techniques of solid state nuclear magnetic resonance (NMR) spectroscopy are constantly being extended to a more diverse range of materials, pressing into service an ever-expanding range of nuclides including some previously considered too intractable to provide usable results. At the same time, new developments in both hardware and software are being introduced and refined. This book covers the most important of these new developments. With sections addressed to non-specialist researchers (providing accessible answers to the most common questions about the theory and practice of NMR asked by novices) as well as a more specialised and up-to-date treatment of the most important areas of inorganic materials research to which NMR has application, this book should be useful to NMR users whatever their level of expertise and whatever inorganic materials they wish to study.

  14. Percolation Phenomena For New Magnetic Composites And Tim Nanocomposites Materials

    Directory of Open Access Journals (Sweden)

    Ahmed Thabet Mohamed

    2015-01-01

    Full Text Available This paper presents a theoretical investigation in order to obtain new composite and nanocomposite magnetic industrial materials. The effective conductivity and thermal effective conductivity have been predicted by adding various types and percentages of conductive particles (Al2O3, MgO, ZnO, Graphite etc. to the main matrices of Epoxy, Iron and Silicon for formulating new composite and nanocomposite industrial materials. The characterization of effective conductivity of new polymeric composites has been investigated with various applied forces, inclusion types and their concentrations. In addition, the effect of inclusion types and their concentrations on the effective thermal conductivities of thermal interface nanocomposite industrial materials has been explained and discussed.

  15. High resistivity iron-based, thermally stable magnetic material for on-chip integrated inductors

    Science.gov (United States)

    Deligianni, Hariklia; Gallagher, William J.; Mason, Maurice; O'Sullivan, Eugene J.; Romankiw, Lubomyr T.; Wang, Naigang

    2017-03-07

    An on-chip magnetic structure includes a palladium activated seed layer and a substantially amorphous magnetic material disposed onto the palladium activated seed layer. The substantially amorphous magnetic material includes nickel in a range from about 50 to about 80 atomic % (at. %) based on the total number of atoms of the magnetic material, iron in a range from about 10 to about 50 at. % based on the total number of atoms of the magnetic material, and phosphorous in a range from about 0.1 to about 30 at. % based on the total number of atoms of the magnetic material. The magnetic material can include boron in a range from about 0.1 to about 5 at. % based on the total number of atoms of the magnetic material.

  16. High resistivity iron-based, thermally stable magnetic material for on-chip integrated inductors

    Energy Technology Data Exchange (ETDEWEB)

    Deligianni, Hariklia; Gallagher, William J.; Mason, Maurice; O' Sullivan, Eugene J.; Romankiw, Lubomyr T.; Wang, Naigang

    2017-10-17

    An on-chip magnetic structure includes a palladium activated seed layer and a substantially amorphous magnetic material disposed onto the palladium activated seed layer. The substantially amorphous magnetic material includes nickel in a range from about 50 to about 80 atomic % (at. %) based on the total number of atoms of the magnetic material, iron in a range from about 10 to about 50 at. % based on the total number of atoms of the magnetic material, and phosphorous in a range from about 0.1 to about 30 at. % based on the total number of atoms of the magnetic material. The magnetic material can include boron in a range from about 0.1 to about 5 at. % based on the total number of atoms of the magnetic material.

  17. Analysis of ringing effects due to magnetic core materials in pulsed nuclear magnetic resonance circuits

    Energy Technology Data Exchange (ETDEWEB)

    Prabhu Gaunkar, N., E-mail: neelampg@iastate.edu; Bouda, N. R. Y.; Nlebedim, I. C.; Hadimani, R. L.; Mina, M.; Jiles, D. C. [Department of Electrical and Computer Engineering, Iowa State University, Ames, Iowa 50011 (United States); Bulu, I.; Ganesan, K.; Song, Y. Q. [Schlumberger-Doll Research, Cambridge, Massachusetts 02139 (United States)

    2015-05-07

    This work presents investigations and detailed analysis of ringing in a non-resonant pulsed nuclear magnetic resonance (NMR) circuit. Ringing is a commonly observed phenomenon in high power switching circuits. The oscillations described as ringing impede measurements in pulsed NMR systems. It is therefore desirable that those oscillations decay fast. It is often assumed that one of the causes behind ringing is the role of the magnetic core used in the antenna (acting as an inductive load). We will demonstrate that an LRC subcircuit is also set-up due to the inductive load and needs to be considered due to its parasitic effects. It is observed that the parasitics associated with the inductive load become important at certain frequencies. The output response can be related to the response of an under-damped circuit and to the magnetic core material. This research work demonstrates and discusses ways of controlling ringing by considering interrelationships between different contributing factors.

  18. Knitted radar absorbing materials (RAM) based on nickel–cobalt magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Teber, Ahmet, E-mail: aht10003@engr.uconn.edu [Department of Electrical and Computer Engineering, University of Connecticut, Storrs, CT 06269 (United States); Unver, Ibrahim, E-mail: iunver@gtu.edu.tr [Department of Physics, Gebze Technical University, Kocaeli 41400 (Turkey); Kavas, Huseyin, E-mail: huseyin.kavas@medeniyet.edu.tr [Department of Physics, Istanbul Medeniyet University, Istanbul 34000 (Turkey); Aktas, Bekir, E-mail: aktas@gtu.edu.tr [Department of Physics, Gebze Technical University, Kocaeli 41400 (Turkey); Bansal, Rajeev, E-mail: rajeev@engr.uconn.edu [Department of Electrical and Computer Engineering, University of Connecticut, Storrs, CT 06269 (United States)

    2016-05-15

    There has been a long-standing interest in the development of flexible, lightweight, thin, and reconfigurable radar absorbing materials (RAM) for military applications such as camouflaging ground-based hardware against airborne radar observation. The use of polymeric Polyacrylonitrile (PAN) fabrics as a host matrix for magnetic metal nano-particles (either at the yarn-stage or after weaving the fabric) for shielding and absorbing applications has been described in the literature. In our experimental investigation, the relative concentrations of Nickel and Cobalt as well as the coating time are varied with a view to optimizing the microwave absorption characteristics of the resulting PAN-based composite material in the radar-frequency bands (X, K{sub u}, and K). It is found that the PAN samples with the shortest coating time have the best return losses (under −20 dB return loss over a moderate bandwidth). - Graphical abstract: Here, we added the graphical abstract that provides summary the contents of the article in a concise pictorial form. - Highlights: • Flexible lightweight, thin, reconfigurable radar absorbing materials are proposed. • Polyacrylonitrile (PAN) fabrics are coated with nickel, cobalt magnetic materials. • The coating times affects microwave constitutive parameters and absorption. • Microwave absorption measurements were done via transmission line technique. • Microwave absorption is due to dielectric losses rather than magnetic losses.

  19. Student understanding of electric and magnetic fields in materials

    Science.gov (United States)

    Mitchem, Savannah L.; Zohrabi Alaee, Dina; Sayre, Eleanor C.

    2017-09-01

    We discuss the clusters of resources that emerge when upper-division students write about electromagnetic fields in linear materials. The data analyzed for this paper come from students' written tests in an upper-division electricity and magnetism course. We examine how these clusters change with time and context. The evidence shows that students benefit from activating resources related to the internal structure of the atom when thinking about electric fields and their effect on materials. We argue that facilitating activation of certain resources by the instructor in the classroom can affect the plasticity of those resources in the student, making them more solid and easily activated. We find that the wording of the questions posed to students affects which resources are activated, and that students often fill in resources to link known phenomena to phenomena described by the question when lacking detailed mental models.

  20. Student understanding of electric and magnetic fields in materials

    CERN Document Server

    Mitchem, Savannah L; Sayre, Eleanor C

    2016-01-01

    We discuss the clusters of resources that emerge when upper-division students enrolled in an upper-division electricity and magnetism course write about fields in linear materials. We examine how these clusters change with time and context. The evidence shows that students benefit from activating resources related to the internal structure of the atom when thinking about electric fields and their effect on materials. We argue that facilitating activation of certain resources by the instructor in the classroom can affect the plasticity of those resources in the student, making them more solid and easily activated. We find that the wording of the questions posed to students affects which resources are activated, and that students often fill in resources to link known phenomena to phenomena described by the question when lacking detailed mental models.

  1. Electromagnetic Processing of Materials Materials Processing by Using Electric and Magnetic Functions

    CERN Document Server

    Asai, Shigeo

    2012-01-01

    This book is both a course book and a monograph. In fact, it has developed from notes given to graduate course students on materials processing in the years 1989 to 2006. Electromagnetic Processing of Materials (EPM), originates from a branch of materials science and engineering developed in the 1980s as a field aiming to create new materials and/or design processes by making use of various functions which appear when applying the electric and magnetic fields to materials. It is based on transport phenomena, materials processing and magnetohydrodynamics. The first chapter briefly introduces the history, background and technology of EPM. In the second chapter, the concept of transport phenomena is concisely introduced and in the third chapter the essential part of magnetohydrodynamics is transcribed and readers are shown that the concept of transport phenomena does not only apply to heat, mass and momentum, but also magnetic field. The fourth chapter describes electromagnetic processing of electrica...

  2. Materials processing in a magnetic force opposed to the gravity

    Energy Technology Data Exchange (ETDEWEB)

    Tournier, R.F. E-mail: tournier@labs.polycnrs-gre.fr; Beaugnon, E.; Noudem, J.; Rakotoarison, S

    2001-05-01

    High magnetic fields can levitate diamagnetic substances. Conducting paramagnetic liquids can be levitated by combining electromagnetic and magnetic forces. Some recent examples of magnetic processing are given to enlighten some experimental difficulties related to solidification. Levitation appears as a particular magnetic processing. There are other concepts to damp convection in magnetic liquids, to modify and orient the solidified microstructure. An exciting perspective is the convection suppression in a magnetic liquid by using much smaller magnetic forces than the levitation force.

  3. Materials, Strands, and Cables for Superconducting Accelerator Magnets. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Sumption, Mike D. [Ohio State University, Columbia, OH (United States); Collings, Edward W. [Ohio State University, Columbia, OH (United States)

    2014-09-19

    This report focuses on Materials, Strands and Cables for High Energy Physics Particle accelerators. In the materials area, work has included studies of basic reactions, diffusion, transformations, and phase assemblage of Nb3Sn. These materials science aspects have been married to results, in the form of flux pinning, Bc2, Birr, and transport Jc, with an emphasis on obtaining the needed Jc for HEP needs. Attention has also been paid to the “intermediate-temperature superconductor”, magnesium diboride emphasis being placed on (i) irreversibility field enhancement, (ii) critical current density and flux pinning, and (iii) connectivity. We also report on studies of Bi-2212. The second area of the program has been in the area of “Strands” in which, aside from the materials aspect of the conductor, its physical properties and their influence on performance have been studied. Much of this work has been in the area of magnetization estimation and flux jump calculation and control. One of the areas of this work was strand instabilities in high-performance Nb3Sn conductors due to combined fields and currents. Additionally, we investigated quench and thermal propagation in YBCO coated conductors at low temperatures and high fields. The last section, “Cables”, focussed on interstrand contact resistance, ICR, it origins, control, and implications. Following on from earlier work in NbTi, the present work in Nb3Sn has aimed to make ICR intermediate between the two extremes of too little contact (no current sharing) and too much (large and unacceptable magnetization and associated beam de-focussing). Interstrand contact and current sharing measurements are being made on YBCO based Roebel cables using transport current methods. Finally, quench was investigated for YBCO cables and the magnets wound from them, presently with a focus on 50 T solenoids for muon collider applications.

  4. Development of High-frequency Soft Magnetic Materials for Power Electronics

    Directory of Open Access Journals (Sweden)

    LIU Jun-chang

    2017-05-01

    Full Text Available The new requirements of high-frequency magnetic properties are put forward for electronic components with the rapid development of power electronics industry and the use of new electromagnetic materials. The properties of magnetic core, which is the key unit of electronic components, determine the performance of electronic components directly. Therefore, it's necessary to study the high-frequency soft magnetic materials. In this paper, the development history of four types of soft magnetic materials was reviewed. The advantages and disadvantages of each kind of soft magnetic materials and future development trends were pointed out. The emphases were placed on the popular soft magnetic composite materials in recent years. The tendency is to develop high-frequency soft magnetic composite materials with the particle size controllable, uniform coating layer on the core and a mass production method from laboratory to industrialization.

  5. Carbon based magnetism an overview of the magnetism of metal free carbon-based compounds and materials

    CERN Document Server

    Makarova, Tatiana

    2006-01-01

    Magnetism is one of the most intriguing phenomena observed in nature. Magnetism is relevant to physics and geology, biology and chemistry. Traditional magnets, an ubiquitous part of many everyday gadgets, are made of heavy iron- or nickel based materials. Recently there have been reports on the observation of magnetism in carbon, a very light and biocompatible element. Metal-free carbon structures exhibiting magnetic ordering represent a new class of materials and open a novel field of research that could lead to many new technologies. · The most complete, detailed, and accurate Guide in the magnetism of carbon · Dynamically written by the leading experts · Deals with recent scientific highlights · Gathers together chemists and physicists, theoreticians and experimentalists · Unified treatment rather than a series of individually authored papers · Description of genuine organic molecular ferromagnets · Unique description of new carbon materials with Curie temperatures well above ambient.

  6. Method and apparatus for separating materials magnetically. [Patent application; iron pyrite from coal

    Science.gov (United States)

    Hise, E.C. Jr.; Holman, A.S.; Friedlaender, F.J.

    1980-11-06

    Magnetic and nonmagnetic materials are separated by passing stream thereof past coaxial current-carrying coils which produce a magnetic field wherein intensity varies sharply with distance radially of the axis of the coils.

  7. Composite Materials with Magnetically Aligned Carbon Nanoparticles Having Enhanced Electrical Properties and Methods of Preparation

    Science.gov (United States)

    Hong, Haiping (Inventor); Peterson, G.P. (Bud) (Inventor); Salem, David R. (Inventor)

    2016-01-01

    Magnetically aligned carbon nanoparticle composites have enhanced electrical properties. The composites comprise carbon nanoparticles, a host material, magnetically sensitive nanoparticles and a surfactant. In addition to enhanced electrical properties, the composites can have enhanced mechanical and thermal properties.

  8. Artifacts by dental materials on magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Hyun Sook; Choi, Deuk Lin; Kim, Ki Jung [Soonchunhyang University Hospital, Asan (Korea, Republic of); Suh, Won Hyuck [Korea University Hospital, Seoul (Korea, Republic of)

    1992-05-15

    Magnetic resonance imaging (MRI) has proved to be a valuable method for evaluation of the head and neck. Unfortunately, metallic devices associated with certain dental fillings and appliances often cause variable artifacts that can obscure normal or pathologic conditions on MR and computed tomography. In this work, we assessed the MR appearance of dental prosthetic materials in vitro and in vivo including precious alloys, nonprecions alloys, resin, amalgam and titanium alloy. For in vivo studies, these materials were placed in healthy volunteer's mouths and then images were assessed. Analysis of the appearance of shape and extent of artifact, and observed influence of these artifacts on the image interpretation at 0.2 Tesla permanent type MR scanner were valuated. Material used as temporary or permanent filling of crowns such as amalgam, precious alloy and, microfilled resin did not cause artifact on the image. The size of the artifact produced by the nonprecious alloys was influenced by the ferromagnetism of the object and the volume prosthesis, and was related to the scanning sequence. Nonprecious alloys produced minimal local signal distortion, where precious alloys, and dental resin had no effect on the MR images in vivo. These results were mainly from a low field strength MR scanner used in this study.

  9. Correlation Between Domain Behavior and Magnetic Properties of Materials

    Energy Technology Data Exchange (ETDEWEB)

    Leib, Jeffrey Scott [Iowa State Univ., Ames, IA (United States)

    2003-01-01

    Correlation between length scales in the field of magnetism has long been a topic of intensive study. The long-term desire is simple: to determine one theory that completely describes the magnetic behavior of matter from an individual atomic particle all the way up to large masses of material. One key piece to this puzzle is connecting the behavior of a material's domains on the nanometer scale with the magnetic properties of an entire large sample or device on the centimeter scale. In the first case study involving the FeSiAl thin films, contrast and spacing of domain patterns are clearly related to microstructure and stress. Case study 2 most clearly demonstrates localized, incoherent domain wall motion switching with field applied along an easy axis for a square hysteresis loop. In case study 3, axis-specific images of the complex Gd-Si-Ge material clearly show the influence of uniaxial anisotropy. Case study 4, the only study with the sole intent of creating domain structures for imaging, also demonstrated in fairly simple terms the effects of increasing stress on domain patterns. In case study 5, it was proven that the width of magnetoresistance loops could be quantitatively predicted using only MFM. When all of the case studies are considered together, a dominating factor seems to be that of anisotropy, both magneticrostaylline and stress induced. Any quantitative bulk measurements heavily reliant on K coefficients, such as the saturation fields for the FeSiAl films, Hc in cases 1, 3, and 5, and the uniaxial character of the Gd5(Si2Ge2), transferred to and from the domain scale quite well. In-situ measurements of domain rotation and switching, could also be strongly correlated with bulk magnetic properties, including coercivity, Ms, and hysteresis loop shape. In most cases, the qualitative nature of the domain structures, when properly considered, matched quite well to what might have been expected

  10. Nuclear Magnetic Resonance Study of Nanoscale Ionic Materials

    KAUST Repository

    Oommen, Joanna Mary

    2010-08-13

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

  11. Numerical study and design optimization of electromagnetic energy harvesters integrated with flexible magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Sang Won [Hanyang University, Seoul (Korea, Republic of)

    2017-05-15

    This study presents a new design of an electromagnetic energy harvester integrated with a soft magnetic material. The harvester design optimizes the magnetic material characteristics and the size of a rectangular permanent magnet. The design employs a complete magnetic circuit made of (1) a thin-film soft magnetic material that facilitates a flexible but highly (magnetically) permeable beam and (2) an optimally-sized magnet that maximizes the harvester performance. The design is demonstrated to reduce magnetic flux leakage, and thus considerably enhances both magnetic flux density (B) and its change by time (dB/dt), which both influence harvester performance. The improvement in harvester performances strongly depends on critical design parameters, especially, the magnet size and characteristics of magnetic materials, including permeability, stiffness, and thickness. The analyses conclude that recently-introduced nanomaterials (having ultrahigh magnetic permeability) can potentially innovate harvester performances. However, the performance may be degraded without design optimization. Once optimized, the integrated nanomaterials facilitate a significant improvement compared with a conventional design without integrated magnetic materials.

  12. Journal of Applied Physics. Volume 63. Number 8. Part 2A. Proceedings of the Annual conference on Magnetism and Magnetic Materials (32nd) Held in Chicago, Illinois on 9-12 November 1987

    Science.gov (United States)

    Materials; Crystalline Magnetic Multilayers; Itinerant Magnetism and Electronic Structure; R-Fe Alloying and Processing; Low-Dimensional Magnetism; Compounds and Magnetochemistry ; and Magnetic Compounds and Alloys. Symposia.

  13. Characterization of magnetic material in the mound-building termite Macrotermes gilvus in Southeast Asia

    Science.gov (United States)

    Esa, Mohammad Faris Mohammad; Rahim, Faszly; Hassan, Ibrahim Haji; Hanifah, Sharina Abu

    2015-09-01

    Magnetic material such as magnetite are known as particles that respond to external magnetic field with their ferromagnetic properties as they are believed contribute to in responding to the geomagnetic field. These particles are used by terrestrial animals such as termites for navigation and orientation. Since our earth react as giant magnetic bar, the magnitude of this magnetic field present by intensity and direction (inclination and direction). The magnetic properties and presence of magnetite in termites Macrotermes gilvus, common mound-building termite were tested. M. gilvus termites was tested with a Vibrating Sample Magnetometer VSM to determine the magnetic properties of specimen. The crushed body sample was characterized with X-Ray Diffraction XRD to show the existent of magnetic material (magnetite) in the specimens. Results from VSM indicate that M. gilvus has diamagnetism properties. The characterization by XRD shows the existent of magnetic material in our specimen in low concentration.

  14. Far-infrared spectroscopy of lanthanide-based molecular magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Haas, Sabrina

    2015-05-13

    This thesis demonstrates the applicability of far-infrared spectroscopy for the study of the crystal-field splitting of lanthanides in single-molecular magnetic materials. The far-infrared studies of three different kinds of single-molecular-magnetic materials, a single-ion magnet, a single-chain magnet and an exchange-coupled cluster, yielded a deeper understanding of the crystal-field splitting of the lanthanides in these materials. In addition, our results offered the opportunity to gain a deeper insight into the relaxation processes of these materials.

  15. Apparatus and method for materials processing utilizing a rotating magnetic field

    Science.gov (United States)

    Muralidharan, Govindarajan; Angelini, Joseph A.; Murphy, Bart L.; Wilgen, John B.

    2017-04-11

    An apparatus for materials processing utilizing a rotating magnetic field comprises a platform for supporting a specimen, and a plurality of magnets underlying the platform. The plurality of magnets are configured for rotation about an axis of rotation intersecting the platform. A heat source is disposed above the platform for heating the specimen during the rotation of the plurality of magnets. A method for materials processing utilizing a rotating magnetic field comprises providing a specimen on a platform overlying a plurality of magnets; rotating the plurality of magnets about an axis of rotation intersecting the platform, thereby applying a rotating magnetic field to the specimen; and, while rotating the plurality of magnets, heating the specimen to a desired temperature.

  16. Magnetic and Electrical Characteristics of Cobalt-Based Amorphous Materials and Comparison to a Permalloy Type Polycrystalline Material

    Science.gov (United States)

    Wieserman, William R.; Schwarze, Gene E.; Niedra, Janis M.

    2005-01-01

    Magnetic component designers are always looking for improved soft magnetic core materials to increase the efficiency, temperature rating and power density of transformers, motors, generators and alternators, and energy density of inductors. In this paper, we report on the experimental investigation of commercially available cobalt-based amorphous alloys which, in their processing, were subjected to two different types of magnetic field anneals: A longitudinal magnetic field anneal or a transverse magnetic field anneal. The longitudinal field annealed material investigated was Metglas 2714A. The electrical and magnetic characteristics of this material were investigated over the frequency range of 1 to 200 kHz and temperature range of 23 to 150 C for both sine and square wave voltage excitation. The specific core loss was lower for the square than the sine wave voltage excitation for the same maximum flux density, frequency and temperature. The transverse magnetic field annealed core materials include Metglas 2714AF and Vacuumschmelze 6025F. These two materials were experimentally characterized over the frequency range of 10 to 200 kHz for sine wave voltage excitation and 23 C only. A comparison of the 2174A to 2714AF found that 2714AF always had lower specific core loss than 2714A for any given magnetic flux density and frequency and the ratio of specific core loss of 2714A to 2714AF was dependent on both magnetic flux density and frequency. A comparison was also made of the 2714A, 2714AF, and 6025F materials to two different tape thicknesses of the polycrystalline Supermalloy material and the results show that 2714AF and 6025F have the lowest specific core loss at 100 kHz over the magnetic flux density range of 0.1 to 0.4 Tesla.

  17. Secondary emission yield at low-primary energies of magnetic materials for anti-multipactor applications

    CERN Document Server

    Aguilera, L; Olano, L; Casas, A; Morales, P; Vázquez, M; Galán, L; Caspers, F; Costa-Pinto, P; Taborelli, M; Raboso, D

    2014-01-01

    Secondary electron emission processes under electron bombardment are central to many effects at surfaces and interfaces, and to many in vacuum high power RF electronic devices where multipactor can be very intense [1,2]. Ferrite materials are usually used in microwave components used in space telecommunication systems, as circulators, phase-shifters, switches, and isolators. The physics of the multipactor phenomenon existing in microwave devices based on ferrite materials is an important issue and it is urgent to be researched [3]. One difficulty in the analysis of the multipactor effect in RF components containing ferrite lies on the fact that this material is an anysotropic magnetic medium controlled by an applied permanent magnetic field, which is used to magnetize the ferrite material. SEY and other properties (structure, magnetic behaviour,...) of soft-magnetic materials were studied in this work. MnZn soft ferrites magnets are suitable in the situation of frequency < 3MHz, low loss and high μi. Comp...

  18. Magnetic mesoporous material for the sequestration of algae

    Science.gov (United States)

    Trewyn, Brian G.; Kandel, Kapil; Slowing, Igor Ivan; Lee, Show-Ling

    2014-09-09

    The present invention provides a magnetic mesoporous nanoparticle that includes a mesoporous silicate nanoparticle and iron oxide. The present invention also provides a method of using magnetic mesoporous nanoparticles to sequester microorganisms from a media.

  19. Knitted radar absorbing materials (RAM) based on nickel-cobalt magnetic materials

    Science.gov (United States)

    Teber, Ahmet; Unver, Ibrahim; Kavas, Huseyin; Aktas, Bekir; Bansal, Rajeev

    2016-05-01

    There has been a long-standing interest in the development of flexible, lightweight, thin, and reconfigurable radar absorbing materials (RAM) for military applications such as camouflaging ground-based hardware against airborne radar observation. The use of polymeric Polyacrylonitrile (PAN) fabrics as a host matrix for magnetic metal nano-particles (either at the yarn-stage or after weaving the fabric) for shielding and absorbing applications has been described in the literature. In our experimental investigation, the relative concentrations of Nickel and Cobalt as well as the coating time are varied with a view to optimizing the microwave absorption characteristics of the resulting PAN-based composite material in the radar-frequency bands (X, Ku, and K). It is found that the PAN samples with the shortest coating time have the best return losses (under -20 dB return loss over a moderate bandwidth).

  20. Magnetic nanofiber composite materials and devices using same

    Science.gov (United States)

    Chen, Xing; Zhou, Ziyao

    2017-04-11

    A nonreciprocal device is described. It includes a housing, a waveguide layer and at least one layer of magnetic nanofiber composite. The magnetic nanofiber composite layer is made up of a polymer base layer, a dielectric matrix comprising magnetic nanofibers. The nanofibers have a high aspect ratio and wherein said dielectric matrix is embedded in the polymer base layer.

  1. Mechanical alignment of particles for use in fabricating superconducting and permanent magnetic materials

    Science.gov (United States)

    Nellis, William J.; Maple, M. Brian

    1992-01-01

    A method for mechanically aligning oriented superconducting or permanently magnetic materials for further processing into constructs. This pretreatment optimizes the final crystallographic orientation and, thus, properties in these constructs. Such materials as superconducting fibers, needles and platelets are utilized.

  2. Biasing and fast degaussing circuit for magnetic materials

    Science.gov (United States)

    Dress, W.B. Jr.; McNeilly, D.R.

    1983-10-04

    A dual-function circuit is provided which may be used to both magnetically bias and alternately, quickly degauss a magnetic device. The circuit may be magnetically coupled or directly connected electrically to a magnetic device, such as a magnetostrictive transducer, to magnetically bias the device by applying a dc current and alternately apply a selectively damped ac current to the device to degauss the device. The circuit is of particular value in many systems which use magnetostrictive transducers for ultrasonic transmission in different propagation modes over very short time periods.

  3. Studies of Energy-Relevant Materials by Nuclear Magnetic Resonance

    Science.gov (United States)

    Cui, Jinfang

    In this thesis, we have used nuclear magnetic resonance (NMR) as a local probe to microscopically study three different families of energy-relevant complex materials, namely the 122 Fe-based superconductors Ca(Fe1-xCox)2As2, GeTe-based thermoelectric tellurides GeTe and detonation nanodiamond. In Chapter 3 and Chapter 4, we investigated the Co substitution effects on static and dynamic magnetic properties of the single-crystalline Ca(Fe 1-xCox)2As2 (x = 0, 0.023, 0.028, 0.033, 0.059) via 75As NMR and resistivity measurements. Robustness of the Fe magnetic moments was evidenced by only slight decreases of Hint, although T N is strongly suppressed with Co substitution in antiferromagnetic (AFM) state. In the paramagnetic (PM) state, the temperature dependence of Knight shift K for all crystals shows similar T-dependence of magnetic susceptibility chi. The spin fluctuations with the q = 0 components are suppressed with Delta/k B. On the other hand, the growth of the stripe-type AFM fluctuations with q = (pi, 0) or (0, pi) upon cooling in the PM state for all samples is evidenced by the T-dependence of (1/ T1Tchi). A pseudogap-like phenomenon, i.e., suppression of the AFM spin fluctuations, was discovered with decreasing temperature below a x-independent characteristic temperature T* ( 100 K) in samples with x ≥ 0.028. In addition, clear evidence for the coexistence and competition of the stripe-type antiferromagnetic and ferromagnetic (FM) spin correlations was given by modified Korringa ratio analysis in Chapter 4. In Chapter 5, we have carried out 125Te NMR measurements to study the electronic properties of Ge50Te50, Ag 2Ge48Te50 and Sb2Ge48Te 50. NMR shift K and 1/T1T of Ge50Te50 are nearly temperature independent at T electron correlations, while Korringa ratio increases slightly at high temperature, suggesting the slight enhancement of the electron correlation. In Chapter 6 and Chapter 7, we have used 13C NMR spectral editing technique to accurately analyze the

  4. Composite particles formed by complexation of poly(methacrylic acid) - stabilized magnetic fluid with chitosan: Magnetic material for bioapplications.

    Science.gov (United States)

    Safarik, Ivo; Stepanek, Miroslav; Uchman, Mariusz; Slouf, Miroslav; Baldikova, Eva; Nydlova, Leona; Pospiskova, Kristyna; Safarikova, Mirka

    2016-10-01

    A simple procedure for the synthesis of magnetic fluid (ferrofluid) stabilized by poly(methacrylic acid) has been developed. This ferrofluid was used to prepare a novel type of magnetically responsive chitosan-based composite material. Both ferrofluid and magnetic chitosan composite were characterized by a combination of microscopy (optical microscopy, TEM, SEM), scattering (static and dynamic light scattering, SANS) and spectroscopy (FTIR) techniques. Magnetic chitosan was found to be a perspective material for various bioapplications, especially as a magnetic carrier for immobilization of enzymes and cells. Lipase from Candida rugosa was covalently attached after cross-linking and activation of chitosan using glutaraldehyde. Baker's yeast cells (Saccharomyces cerevisiae) were incorporated into the chitosan composite during its preparation; both biocatalysts were active after reaction with appropriate substrates. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. [Magnetic micro-/nano-materials: functionalization and their applications in pretreatment for food samples].

    Science.gov (United States)

    Gao, Qiang; Feng, Yuqi

    2014-10-01

    Magnetic solid phase extraction technique, based on functional magnetic materials, is currently a hot topic in the separation and analysis of complex samples. This paper reviews the reported methods for the functionalization of magnetic micro-/nano-materials, such as sur- face grafting organic groups, coating carbon or inorganic oxide, grafting or coating polymer, being loaded to the surface or pores of supports, being introduced into the skeleton of sup- ports, and physically co-mixing methods. Moreover, we briefly introduce the applications of the functional magnetic micro-/nano-materials in pretreatment for food samples.

  6. Magnetic characterization of ferrite materials used in the ELENA magnetic pick-ups

    CERN Document Server

    Favia, Giorgia; CERN. Geneva. ATS Department

    2015-01-01

    The CERN Extra Low ENergy Antiproton (ELENA) Ring is a new synchrotron designed for cooling and further decelerating the 5.3 MeV antiprotons delivered by the CERN Antiproton Decelerator (AD). The ring is equipped with two magnetic pick-ups used for longitudinal beam diagnostics. These ultra low noise AC beam transformers consist of a doubly shielded, ferrite-loaded cavity with a ceramic gap in the beam pipe, a secondary winding to which an ultralow noise JFET head amplifier with feedback is connected. The JFET head amplifier is mounted close to the cavity and the AC beam transformers are covering respectively the 0.003-3MHz frequency range (low frequency type) and 0.8-30 MHz frequency range (high frequency type) [1]. The ferrite material used to couple primary and secondary in the beam transformer, has a key impact in the noise characteristics of the amplifier. For this reason a magnetic characterization of the selected ferrite rings has been carried out and is reported in the following.

  7. Synthesis and characterization of magnetic materials for self-controlled hyperthermia therapy

    OpenAIRE

    Barati, Mohammad Reza

    2017-01-01

    The major challenges in magnetic hyperthermia treatment (MHT) are the low heat generation of magnetic nanoparticles for cancer therapy and the avoidance of overheating via the temperature self-control characteristic at the ideal therapeutic range. Hence the aims of this PhD thesis are to develop a new magnetic implant material with high heat generation and temperature self-control capability, and to study their potential for safe MHT applications. In order to develop a ceramic magnetic im...

  8. High frequency transformers and high Q factor inductors formed using epoxy-based magnetic polymer materials

    Science.gov (United States)

    Sanchez, Robert O.; Gunewardena, Shelton; Masi, James V.

    2005-03-29

    An electrical component in the form of an inductor or transformer is disclosed which includes one or more coils and a magnetic polymer material located near the coils or supporting the coils to provide an electromagnetic interaction therewith. The magnetic polymer material is preferably a cured magnetic epoxy which includes a mercaptan derivative having a ferromagnetic atom chemically bonded therein. The ferromagnetic atom can be either a transition metal or rare-earth atom.

  9. Maximizing hysteretic losses in magnetic ferrite nanoparticles via model-driven synthesis and materials optimization.

    Science.gov (United States)

    Chen, Ritchie; Christiansen, Michael G; Anikeeva, Polina

    2013-10-22

    This article develops a set of design guidelines for maximizing heat dissipation characteristics of magnetic ferrite MFe2O4 (M = Mn, Fe, Co) nanoparticles in alternating magnetic fields. Using magnetic and structural nanoparticle characterization, we identify key synthetic parameters in the thermal decomposition of organometallic precursors that yield optimized magnetic nanoparticles over a wide range of sizes and compositions. The developed synthetic procedures allow for gram-scale production of magnetic nanoparticles stable in physiological buffer for several months. Our magnetic nanoparticles display some of the highest heat dissipation rates, which are in qualitative agreement with the trends predicted by a dynamic hysteresis model of coherent magnetization reversal in single domain magnetic particles. By combining physical simulations with robust scalable synthesis and materials characterization techniques, this work provides a pathway to a model-driven design of magnetic nanoparticles tailored to a variety of biomedical applications ranging from cancer hyperthermia to remote control of gene expression.

  10. Spin waves damping in nanometre-scale magnetic materials (Review Article)

    Science.gov (United States)

    Krivoruchko, V. N.

    2015-09-01

    Spin dynamics in magnetic nanostructured materials is a topic of great current interest. To describe spin motions in such magnetic systems, the phenomenological Landau-Lifshitz (LL), or the LL-Gilbert (LLG), equation is widely used. Damping term is one of the dominant features of magnetization dynamics and plays an essential role in these equations of motion. The form of this term is simple; however, an important question arises whether it provides a proper description of the magnetization coupling to the thermal bath and the related magnetic fluctuations in the real nanometre-scale magnetic materials. It is now generally accepted that for nanostructured systems the damping term in the LL (LLG) equation fails to account for the systematics of the magnetization relaxation, even at the linear response level. In ultrathin films and nanostructured magnets particular relaxation mechanisms arise, extrinsic and intrinsic, which are relevant at nanometre-length scales, yet are not so efficient in bulk materials. These mechanisms of relaxation are crucial for understanding the magnetization dynamics that results in a linewidth dependence on the nanomagnet's size. We give an overview of recent efforts regarding the description of spin waves damping in nanostructured magnetic materials. Three types of systems are reviewed: ultrathin and exchange-based films, magnetic nanometre-scale samples and patterned magnetic structures. The former is an example of a rare case where consideration can be done analytically on microscopic footing. The latter two are typical samples when analytical approaches hardly have to be developed and numerical calculations are more fruitful. Progress in simulations of magnetization dynamics in nanometre-scale magnets gives hopes that a phenomenological approach can provide us with a realistic description of spin motions in expanding diverse of magnetic nanostructures.

  11. Toward black-box-type full- and reduced-dimensional variational (ro)vibrational computations

    Science.gov (United States)

    Mátyus, Edit; Czakó, Gábor; Császár, Attila G.

    2009-04-01

    A black-box-type algorithm is presented for the variational computation of energy levels and wave functions using a (ro)vibrational Hamiltonian expressed in an arbitrarily chosen body-fixed frame and in any set of internal coordinates of full or reduced vibrational dimensionality. To make the required numerical work feasible, matrix representation of the operators is constructed using a discrete variable representation (DVR). The favorable properties of DVR are exploited in the straightforward and numerically exact inclusion of any representation of the potential and the kinetic energy including the G matrix and the extrapotential term. In this algorithm there is no need for an a priori analytic derivation of the kinetic energy operator, as all of its matrix elements at each grid point are computed numerically either in a full- or a reduced-dimensional model. Due to the simple and straightforward definition of reduced-dimensional models within this approach, a fully anharmonic variational treatment of large, otherwise intractable molecular systems becomes available. In the computer code based on the above algorithm, there is no inherent limitation for the maximally coupled number of vibrational degrees of freedom. However, in practice current personal computers allow the treatment of about nine fully coupled vibrational dimensions. Computation of vibrational band origins of full and reduced dimensions showing the advantages and limitations of the algorithm and the related computer code are presented for the water, ammonia, and methane molecules.

  12. Development of advanced biorefinery concepts using magnetically responsive materials

    Czech Academy of Sciences Publication Activity Database

    Šafařík, Ivo; Pospišková, K.; Baldíková, E.; Šafaříková, Miroslava

    2016-01-01

    Roč. 116, DEC (2016), s. 17-26 ISSN 1369-703X R&D Projects: GA ČR GA13-13709S Institutional support: RVO:67179843 Keywords : saccharomyces-cerevisiae cells * solid acid catalysts * Separation * Biocatalysis * Immobilization * Bioconversion * Magnetic particles * Magnetic enzymes and cells Subject RIV: EH - Ecology, Behaviour Impact factor: 2.892, year: 2016

  13. Development of advanced biorefinery concepts using magnetically responsive materials

    Czech Academy of Sciences Publication Activity Database

    Šafařík, Ivo; Pospíšková, K.; Baldíková, E.; Šafaříková, Miroslava

    2016-01-01

    Roč. 116, SI (2016), s. 17-26 ISSN 1369-703X Institutional support: RVO:60077344 Keywords : separation * biocatalysis * immobilization * bioconversion * magnetic particles * magnetic enzymes and cells Subject RIV: GM - Food Processing Impact factor: 2.892, year: 2016

  14. Ferromagnetic resonance of isotropic heterogeneous magnetic materials: theory and experiments

    CERN Document Server

    Chevalier, A; Le Floc'h, M

    2000-01-01

    Experimental variations of the ferromagnetic resonance (FMR) recorded on soft composite bodies are presented and their interpretation is undertaken. A successful application is performed for the Kittel expression of the FMR, initially written for an ellipsoid placed in vacuum, to a magnetic inclusion of the composite. This model includes the demagnetizing effects due to the magnetic inclusions.

  15. TOPICAL REVIEW: Phase-field modeling of microstructure evolutions in magnetic materials

    Directory of Open Access Journals (Sweden)

    Toshiyuki Koyama

    2008-01-01

    Full Text Available Recently, the phase-field method has been extended and utilized across many fields of materials science. Since this method can incorporate, systematically, the effect of the coherency induced by lattice mismatch and the applied stress as well as the external electrical and magnetic fields, it has been applied to many material processes including solidification, solid-state phase transformations and various types of complex microstructure changes. In this paper, we focus on the recent phase-field simulations of real magnetic materials, and the simulation method for magnetic materials is explained comprehensively. Several applications of the phase-field method to clarifying the microstructure changes in magnetic materials, such as Ni2MnGa ferromagnetic shape memory alloy, FePt nanogranular thin film, Co–Sm–Cu rare-earth magnet, Fe–Cr–Co spinodal magnet, and Fe–C steel with external magnetic field, are demonstrated. Furthermore, the general concept of the effective strategy for controlling microstructure in magnetic materials is proposed.

  16. EXPERIMENTATION OF THREE PHASE OUTER ROTATING SWITCHED RELUCTANCE MOTOR WITH SOFT MAGNETIC COMPOSITE MATERIALS

    Directory of Open Access Journals (Sweden)

    N. C. LENIN

    2017-01-01

    Full Text Available This paper presents the application of Soft Magnetic Composite (SMC material in Outer Rotating Switched Reluctance Motor (ORSRM. The presented stator core of the Switched Reluctance Motor was made of two types of material, the classical laminated silicon steel sheet and the soft magnetic composite material. First, the stator core made of laminated steel has been analysed. The next step is to analyse the identical geometry SRM with the soft magnetic composite material, SOMALOY for its stator core. The comparisons of both cores include the calculated torque and torque ripple, magnetic conditions, simplicity of fabrication and cost. The finite element method has been used to analyse the magnetic conditions and the calculated torque. Finally, tested results shows that SMC is a better choice for SRM in terms of torque ripple and power density.

  17. Development of a low-cost double rotor axial flux motor with soft magnetic composite and ferrite permanent magnet materials

    Science.gov (United States)

    Liu, Chengcheng; Zhu, Jianguo; Wang, Youhua; Guo, Youguang; Lei, Gang; Liu, Xiaojing

    2015-05-01

    This paper proposes a low-cost double rotor axial flux motor (DRAFM) with low cost soft magnetic composite (SMC) core and ferrite permanent magnets (PMs). The topology and operating principle of DRAFM and design considerations for best use of magnetic materials are presented. A 905 W 4800 rpm DRAFM is designed for replacing the high cost NdFeB permanent magnet synchronous motor (PMSM) in a refrigerator compressor. By using the finite element method, the electromagnetic parameters and performance of the DRAFM operated under the field oriented control scheme are calculated. Through the analysis, it is shown that that the SMC and ferrite PM materials can be good candidates for low-cost electric motor applications.

  18. Magnetic Nanowires as Materials for Cancer Cell Destruction

    KAUST Repository

    Contreras, Maria F.

    2015-12-01

    Current cancer therapies are highly cytotoxic and their delivery to exclusively the affected site is poorly controlled, resulting in unavoidable and often severe side effects. In an effort to overcome such issues, magnetic nanoparticles have been recently gaining relevance in the areas of biomedical applications and therapeutics, opening pathways to alternative methods. This led to the concept of magnetic particle hyperthermia in which magnetic nano beads are heated by a high power magnetic field. The increase in temperature kills the cancer cells, which are more susceptible to heat in comparison to healthy cells. In this dissertation, the possibility to kill cancer cells with magnetic nanowires is evaluated. The idea is to exploit a magnetomechanical effect, where nanowires cause cancer cell death through vibrating in a low power magnetic field. Specifically, the magnetic nanowires effects to cells in culture and their ability to induce cancer cell death, when combined with an alternating magnetic field, was investigated. Nickel and iron nanowires of 35 nm diameter and 1 to 5 μm long were synthesized by electrodeposition into nanoporous alumina templates, which were prepared using a two-step anodization process on highly pure aluminum substrates. For the cytotoxicity studies, the nanowires were added to cancer cells in culture, varying the incubation time and the concentration. The cell-nanowire interaction was thoroughly studied at the cellular level (mitochondrial metabolic activity, cell membrane integrity and, apoptosis/necrosis assay), and optical level (transmission electron and confocal microscopy). Furthermore, to investigate their therapeutic potential, an alternating magnetic field was applied varying its intensity and frequency. After the magnetic field application, cells health was measured at the mitochondrial activity level. Cytotoxicity results shed light onto the cellular tolerance to the nanowires, which helped in establishing the appropriate

  19. Streamlined approach to mapping the magnetic induction of skyrmionic materials

    Energy Technology Data Exchange (ETDEWEB)

    Chess, Jordan J., E-mail: jchess@uoregon.edu [Department of Physics, University of Oregon, Eugene, OR 97403 (United States); Montoya, Sergio A. [Center for Memory and Recording Research, University of California, San Diego, CA 92093 (United States); Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, CA 92093 (United States); Harvey, Tyler R. [Department of Physics, University of Oregon, Eugene, OR 97403 (United States); Ophus, Colin [National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Couture, Simon; Lomakin, Vitaliy; Fullerton, Eric E. [Center for Memory and Recording Research, University of California, San Diego, CA 92093 (United States); Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, CA 92093 (United States); McMorran, Benjamin J. [Department of Physics, University of Oregon, Eugene, OR 97403 (United States)

    2017-06-15

    Highlights: • A method to reconstruction the phase of electrons after pasting though a sample that requires a single defocused image is presented. • Restrictions as to when it is appropriate to apply this method are described. • The relative error associated with this method is compared to conventional transport of intensity equation analysis. - Abstract: Recently, Lorentz transmission electron microscopy (LTEM) has helped researchers advance the emerging field of magnetic skyrmions. These magnetic quasi-particles, composed of topologically non-trivial magnetization textures, have a large potential for application as information carriers in low-power memory and logic devices. LTEM is one of a very few techniques for direct, real-space imaging of magnetic features at the nanoscale. For Fresnel-contrast LTEM, the transport of intensity equation (TIE) is the tool of choice for quantitative reconstruction of the local magnetic induction through the sample thickness. Typically, this analysis requires collection of at least three images. Here, we show that for uniform, thin, magnetic films, which includes many skyrmionic samples, the magnetic induction can be quantitatively determined from a single defocused image using a simplified TIE approach.

  20. Modular Approaches to Flouride-Bridged Molecular Magnetic Materials

    DEFF Research Database (Denmark)

    Pedersen, Kasper Steen

    interactions in a lower total spin polynuclear complex had a larger magnetic entropy change during a adiabatic demagnetization than an, all ferromagnetically coupled, complex with a larger spin ground state. Diffuse orbitals and strong magnetic anisotropy resulting from large values of the spinorbit coupling...... of the relevance of the thermally activated Orbach process for magnetization relaxation that is commonly a priori assumed to be of importance in related systems. Furthermore, the chemical robustness of the Er(trensal) system has allowed for outof-crystal studies of vapor- and solution-deposited films...

  1. Is an Apple Magnetic: Magnetic Response of Everyday Materials Supporting Views about the Nature of Science

    Science.gov (United States)

    Laumann, Daniel

    2017-01-01

    Magnetism and its various applications are essential for our daily life and for many technological developments. The term "magnetism" is almost always used as a synonym for ferromagnetism. However, the magnetic properties of the elements of the periodic table indicate that the vast majority of elements are not ferromagnetic, but rather,…

  2. Rigorous joining of advanced reduced-dimensional beam models to three-dimensional finite element models

    Science.gov (United States)

    Song, Huimin

    In the aerospace and automotive industries, many finite element analyses use lower-dimensional finite elements such as beams, plates and shells, to simplify the modeling. These simplified models can greatly reduce the computation time and cost; however, reduced-dimensional models may introduce inaccuracies, particularly near boundaries and near portions of the structure where reduced-dimensional models may not apply. Another factor in creation of such models is that beam-like structures frequently have complex geometry, boundaries and loading conditions, which may make them unsuitable for modeling with single type of element. The goal of this dissertation is to develop a method that can accurately and efficiently capture the response of a structure by rigorous combination of a reduced-dimensional beam finite element model with a model based on full two-dimensional (2D) or three-dimensional (3D) finite elements. The first chapter of the thesis gives the background of the present work and some related previous work. The second chapter is focused on formulating a system of equations that govern the joining of a 2D model with a beam model for planar deformation. The essential aspect of this formulation is to find the transformation matrices to achieve deflection and load continuity on the interface. Three approaches are provided to obtain the transformation matrices. An example based on joining a beam to a 2D finite element model is examined, and the accuracy of the analysis is studied by comparing joint results with the full 2D analysis. The third chapter is focused on formulating the system of equations for joining a beam to a 3D finite element model for static and free-vibration problems. The transition between the 3D elements and beam elements is achieved by use of the stress recovery technique of the variational-asymptotic method as implemented in VABS (the Variational Asymptotic Beam Section analysis). The formulations for an interface transformation matrix and

  3. Penerapan Three Tier-Test untuk Identifikasi Kuantitas Siswa Yang Miskonsepsi Pada Materi Magnet

    Directory of Open Access Journals (Sweden)

    Reny Silviani

    2017-10-01

    Full Text Available Proses pembelajaran yang bersifat informative dan hanya ditekankan pada konsep teoritik saja dapat menyebabkan siswa kurang menguasai konsep ilmiah.Faktor yang menyebabkan rendahnya penguasaan konsep siswa adalah miskonsepsi. Miskonsepsi merupakan kekeliruan dalam memahami suatu konsep materi pembelajaran yang tidak akurat, yang dapat menyebabkan ketidaksesuaian antara konsep yang dimiliki pribadi dengan konsep ilmiah. Dengan adanya miskonsepsi yang terjadi, hal ini dapat menghambat siswa untuk menerima informasi yang baru, sehingga siswa menolak untuk mengubah miskonsepsinya menjadi konsep ilmiah. Penelitian ini bertujuan untuk mengidentifikasi mengenai kuantitas siswa yang miskonsepsi pada materi magnet. Penelitian ini merupakan penelitian deskriptif kuantitatif dengan teknik pengambilan sampel adalah purposive sampling.Instrumen penelitian yang digunakan adalah three tier-test. Penggunaan three tier-test yaitu untuk mengidentifikasi kuantita ssiswa yang miskonsepsi. Jawaban yang telah dianalisis, selanjutnya akan dihitung dalam bentuk persentase. Hasil dari penelitian menunjukkan bahwa terdapat 3 konsep distribusi atau sebaran miskonsepsi pada materi magnet, yaitu; 1. Semua benda berwarna perak ditarik magnet; 2. Tarikan magnet yang lebih besar pasti lebih kuat dari tarikan magnet yang kecil; 3. Semua logam dapat ditarik magnet.Miskonsepsi tertinggi terdapat pada konsep tarikan magnet yang lebih besar pasti lebih kuat dari tarikan magnet yang kecil. Diharapkan hasil dari penelitian ini dapat dijadikan referensi untuk mencari solusi dalam menurunkan kuantitas siswa yang miskonsepsik hususnya pada materi magnet.

  4. Perspectives on Permanent Magnetic Materials for Energy Conversion and Power Generation

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, LH; Jimenez-Villacorta, F

    2012-07-18

    Permanent magnet development has historically been driven by the need to supply larger magnetic energy in ever smaller volumes for incorporation in an enormous variety of applications that include consumer products, transportation components, military hardware, and clean energy technologies such as wind turbine generators and hybrid vehicle regenerative motors. Since the 1960s, the so-called rare-earth "supermagnets," composed of iron, cobalt, and rare-earth elements such as Nd, Pr, and Sm, have accounted for the majority of global sales of high-energy-product permanent magnets for advanced applications. In rare-earth magnets, the transition-metal components provide high magnetization, and the rare-earth components contribute a very large magnetocrystalline anisotropy that donates high resistance to demagnetization. However, at the end of 2009, geopolitical influences created a worldwide strategic shortage of rare-earth elements that may be addressed, among other actions, through the development of rare-earth-free magnetic materials harnessing sources of magnetic anisotropy other than that provided by the rare-earth components. Materials engineering at the micron scale, nanoscale, and Angstrom scales, accompanied by improvements in the understanding and characterization of nanoscale magnetic phenomena, is anticipated to result in new types of permanent magnetic materials with superior performance. DOI: 10.1007/s11661-012-1278-2 (C) The Minerals, Metals & Materials Society and ASM International 2012

  5. Perspectives for high-performance permanent magnets: applications, coercivity, and new materials

    Science.gov (United States)

    Hirosawa, Satoshi; Nishino, Masamichi; Miyashita, Seiji

    2017-03-01

    High-performance permanent magnets are indispensable in the production of high-efficiency motors and generators and ultimately for sustaining the green earth. The central issue of modern permanent magnetism is to realize high coercivity near and above room temperature on marginally hard magnetic materials without relying upon the critical elements such as heavy rare earths by means of nanostructure engineering. Recent investigations based on advanced nanostructure analysis and large-scale first principles calculations have led to significant paradigm shifts in the understandings of coercivity mechanism in Nd-Fe-B permanent magnets, which includes the discovery of the ferromagnetism of the thin (2 nm) intergranular phase surrounding the Nd2Fe14B grains, the occurrence of negative (in-plane) magnetocrystalline anisotropy of Nd ions and some Fe atoms at the interface which degrades coercivity, and visualization of the stochastic behaviors of magnetization in the magnetization reversal process at high temperatures. A major change may occur also in the motor topologies, which is currently overwhelmed by the magnetic flux weakening interior permanent magnet motor type, to other types with variable flux permanent magnet type in some applications to open up a niche for new permanent magnet materials. Keynote talk at 8th International Workshop on Advanced Materials Science and Nanotechnology (IWAMSN2016), 8-12 November 2016, Ha Long City, Vietnam.

  6. A novel approach in recognizing magnetic material with simplified algorithm

    KAUST Repository

    Talukdar, Abdul Hafiz Ibne

    2011-04-01

    In this article a cost-effective and simple system (circuit and algorithm) which allows recognizing different kinds of films by their magneto-field conductive properties is demonstrated. The studied signals are generated by a proposed circuit. This signal was further analyzed (recognized) in frequency domain creating the Fourier frequency spectrum which is easily used to detect the response of magnetic sample. The novel algorithm in detecting magnetic field is presented here with both simulation and experimental results. © 2011 IEEE.

  7. Magnetic-field- and pressure-induced quantum phases in complex materials.

    Science.gov (United States)

    Kim, Minjung; Barath, Harini; Chen, Xiaoqian; Joe, Young-Il; Fradkin, Eduardo; Abbamonte, Peter; Cooper, S Lance

    2010-03-12

    This Progress Report presents temperature-, magnetic-field-, and pressure-dependent Raman measurements of strongly correlated materials such as the charge-ordering manganese perovskites, the multiferroic material TbMnO(3), and the charge-density wave (CDW) materials 1T-TiSe(2) and Cu(x)TiSe(2). These studies illustrate the rich array of phases and properties that can be accessed with field and pressure tuning in these materials, and demonstrate the efficacy of using magnetic-field- and pressure-dependent scattering methods to elucidate the microscopic changes associated with highly tunable behavior in complex materials.

  8. Use of magnetic carbon composites from renewable resource materials for oil spill clean up and recovery

    Science.gov (United States)

    Viswanathan, Tito

    2014-02-11

    A method for separating a liquid hydrocarbon material from a body of water. In one embodiment, the method includes the steps of mixing a plurality of magnetic carbon-metal nanocomposites with a liquid hydrocarbon material dispersed in a body of water to allow the plurality of magnetic carbon-metal nanocomposites each to be adhered by an amount of the liquid hydrocarbon material to form a mixture, applying a magnetic force to the mixture to attract the plurality of magnetic carbon-metal nanocomposites each adhered by an amount of the liquid hydrocarbon material, and removing said plurality of magnetic carbon-metal nanocomposites each adhered by an amount of the liquid hydrocarbon material from said body of water while maintaining the applied magnetic force, wherein the plurality of magnetic carbon-metal nanocomposites is formed by subjecting one or more metal lignosulfonates or metal salts to microwave radiation, in presence of lignin/derivatives either in presence of alkali or a microwave absorbing material.

  9. New oxide magnetic material for sub-4K cryocoolers; Sankabutsu jiseitai no chikureizai eno oyo

    Energy Technology Data Exchange (ETDEWEB)

    Numazawa, T.; Sato, A.; Wada, H. [National Research Inst. of Metals, Tokyo (Japan). Tsukuba Magnet Lab.; Arai, O. [Tokyo Inst. of Tech., Tokyo (Japan)

    2000-05-29

    Aiming at improvement of refrigerating performance below 4 K, magnetic cryocoolers with large heat capacity in this region were examined. Noticing comparatively weak and simple magnetic interaction of oxide magnetic materials, possible substances which have large volume specific heat below 4 K were searched, and found perovskite system rare earth magnetic material GdAlO{sub 3}. Though GdAlO{sub 3} polycrystal shows {lambda} type ferromagnetic transition directly below 4 K, magnetic entropy of Gd is sufficiently maintained, and Gd has a large specific heat peak in 3 {approx} 4 K. Comparing with practical magnetic cryocooler HoCu{sub 2}, this GdAlO{sub 3} was found to have over 3.5 times specific heat. (NEDO)

  10. Temperature Dependence and Magnetic Properties of Injection Molding Tool Materials Used in Induction Heating

    DEFF Research Database (Denmark)

    Guerrier, Patrick; Nielsen, Kaspar Kirstein; Hattel, Jesper Henri

    2015-01-01

    To analyze the heating phase of an induction heated injection molding tool precisely, the temperature-dependent magnetic properties, B–H curves, and the hysteresis loss are necessary for the molding tool materials. Hence, injection molding tool steels, core materials among other materials have...

  11. Estimating body segment orientation by applying inertial and magnetic sensing near ferromagnetic materials

    NARCIS (Netherlands)

    Roetenberg, D.; Baten, Christian T.M.; Veltink, Petrus H.

    Inertial and magnetic sensors are very suitable for ambulatory monitoring of human posture and movements. However, ferromagnetic materials near the sensor disturb the local magnetic field and, therefore, the orientation estimation. A Kalman-based fusion algorithm was used to obtain dynamic

  12. Method of making magnetic, crosslinked chitosan support materials and products thereof

    OpenAIRE

    1997-01-01

    Method for magnetizing crosslinked chitosan support material involving the treatment of carboxyl group-containing, crosslinked chitosan gels with solutions of ferrous chloride followed by treatment with dilute aqueous alkali and then oxidation with molecular oxygen gas to produce highly-enriched magnetized chitosan particles, beads, films and/or coatings.

  13. Survey of high field superconducting material for accelerator magnets

    Energy Technology Data Exchange (ETDEWEB)

    Scahlan, R.; Greene, A.F.; Suenaga, M.

    1986-05-01

    The high field superconductors which could be used in accelerator dipole magnets are surveyed, ranking these candidates with respect to ease of fabrication and cost as well as superconducting properties. Emphasis is on Nb/sub 3/Sn and NbTi. 27 refs., 2 figs. (LEW)

  14. Materials science: Magnetic molecules back in the race

    Science.gov (United States)

    Sessoli, Roberta

    2017-08-01

    Single-molecule magnets have potential data-storage applications, but will need to work at a much higher temperature than has been possible. Two studies suggest that this goal could be met in the near future. See Letter p.439

  15. High performance of low cost soft magnetic materials

    Indian Academy of Sciences (India)

    The exhaustive characterization covers several diverse techniques: X-ray diffraction, Mössbauer spectroscopy, differential scanning calorimetry, differential thermal analysis and magnetic properties. In addition, a brief economic analysis is presented. For the alloys annealed at 813 K, the value of the grain size was 16 nm ...

  16. Exploring Ultrahigh Magnetic Field Processing of Materials for Developing Customized Microstructures and Enhanced Performance

    Energy Technology Data Exchange (ETDEWEB)

    Ludtka, GERALD M.

    2005-03-31

    Thermodynamic calculations based on Gibbs free energy in the magnetization-magnetic intensity-temperature (M-H-T) magnetic equation of state space demonstrate that significantly different phase equilibria may result for those material systems where the product and parent phases exhibit different magnetization responses. These calculations show that the Gibbs free energy is changed by a factor equal to -MdH, where M and H are the magnetization and applied field strength, respectively. Magnetic field processing is directly applicable to a multitude of alloys and compounds for dramatically influencing phase stability and phase transformations. This ability to selectively control microstructural stability and alter transformation kinetics through appropriate selection of the magnetic field strength promises to provide a very robust mechanism for developing and tailoring enhanced microstructures (and even nanostructures through accelerated kinetics) with superior properties for a broad spectrum of material applications. For this Industrial Materials for the Future (IMF) Advanced Materials for the Future project, ferrous alloys were studied initially since this alloy family exhibits ferromagnetism over part of its temperature range of stability and therefore would demonstrate the maximum impact of this novel processing mechanism. Additionally, with these ferrous alloys, the high-temperature parent phase, austenite, exhibits a significantly different magnetization response from the potential product phases, ferrite plus carbide or martensite; and therefore, the solid-state transformation behavior of these alloys will be dramatically influenced by the presence of ultrahigh magnetic fields. Finally, a thermodynamic calculation capability (within ThermoCalc for example) was developed during this project to enable parametric studies to be performed to predict the magnitude of the influence of magnetic processing variables on the phase stability (phase diagrams) in

  17. Magnetically guided micro-droplet using biological magnetic material for smart drug delivery system.

    Science.gov (United States)

    Oh, Darong; Lee, Suwon; Kim, Jinhyuk; Choi, Hongsoo; Seo, Jongmo; Koo, Kyo-in

    2014-01-01

    Biodegradable polymer droplet containing magnetosome demonstrates active propulsion by magnetic field. Magnetosome is extracted from magnetotactic bacteria, AMB-1. Mixture of magnetosome and sodium alginate composes into droplet using the microfluidic device applied Plateau-Rayleigh instability principle. The magnetosome-contained droplet selects its route at the bifurcate microchannels by magnetic field. This shows tissue targeting potential of the proposed drug delivery system.

  18. Magnetic properties of crystalline and amorphous phase-change materials doped with 3d impurities.

    Science.gov (United States)

    Zhang, Wei; Ronneberger, Ider; Li, Yan; Mazzarello, Riccardo

    2012-08-22

    First-principles study of the structural and magnetic properties of cubic and amorphous phase-change materials doped with 3d impurities. We find that Co- and Ni-doped Ge(2) Sb(2) Te(5) is non-magnetic, whereas Cr- and Mn-doped Ge(2) Sb(2) Te(5) is magnetic and exhibits a significant magnetic contrast between the two phases in the ferromagnetic configuration. These results are explained in terms of differences in local structure and hybridization of the impurity d-orbitals with the host states. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Magnetic materials as sorbents for metal/metalloid preconcentration and/or separation. A review.

    Science.gov (United States)

    Giakisikli, Georgia; Anthemidis, Aristidis N

    2013-07-30

    The use of magnetic materials in solid phase extraction has received considerable attention in recent years taking into account many advantages arising from the inherent characteristics of magnetic particles. Magnetic solid phase extraction (MSPE) methodology overcomes problems such as column packing and phase separation, which can be easily performed by applying an external magnetic field. The use of magnetic particles in automatic systems is growing over the last few years making the on-line operation of MSPE a promising technique in the frame of green chemistry. This article aims to provide all recent progress in the research of novel magnetic materials as sorbents for metal preconcentration and determination coupled with different detection systems as well as their implementation in sequential injection and microfluidic systems. In addition, a description of preparation, characterization as well as applications of various types of magnetic materials, either with organic or inorganic coating of the magnetic core, is presented. Concluding remarks and future trends are also commented. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Experimental investigation on the dynamic mechanical properties of soft magnetic entangled metallic wire material

    Science.gov (United States)

    Ma, Yanhong; Zhang, Qicheng; Zhang, Dayi; Hu, Wenzhong; Hong, Jie

    2017-05-01

    This work describes the dynamic characteristics of a novel soft magnetic entangled metallic wire material(SM-EMWM) by the dynamic tests for the first time. The mechanical properties of three batches of SM-EMWMs with different porosities have been investigated under different dynamic loads in different magnetic field intensities. The result shows that its properties (storage modulus and loss factor) have commendably controllable magnetic responses in the magnetic field. In particular, the dynamic damping is more remarkable than its quasi-static performance, and the loss factor can be improved above 50% in the magnetic field of 500 mT. The results indicate that SM-EMWM as a magneto-sensitive smart material possesses a considerable application prospect for the active vibration control with variable stiffness and damping.

  1. PREFACE: 3rd International Workshop on Materials Analysis and Processing in Magnetic Fields (MAP3)

    Science.gov (United States)

    Sakka, Yoshio; Hirota, Noriyuki; Horii, Shigeru; Ando, Tsutomu

    2009-07-01

    The 3rd International Workshop on Materials Analysis and Processing in Materials Fields (MAP3) was held on 14-16 May 2008 at the University of Tokyo, Japan. The first was held in March 2004 at the National High Magnetic Field Laboratory in Tallahassee, USA. Two years later the second took place in Grenoble, France. MAP3 was held at The University of Tokyo International Symposium, and jointly with MANA Workshop on Materials Processing by External Stimulation, and JSPS CORE Program of Construction of the World Center on Electromagnetic Processing of Materials. At the end of MAP3 it was decided that the next MAP4 will be held in Atlanta, USA in 2010. Processing in magnetic fields is a rapidly expanding research area with a wide range of promising applications in materials science. MAP3 focused on the magnetic field interactions involved in the study and processing of materials in all disciplines ranging from physics to chemistry and biology: Magnetic field effects on chemical, physical, and biological phenomena Magnetic field effects on electrochemical phenomena Magnetic field effects on thermodynamic phenomena Magnetic field effects on hydrodynamic phenomena Magnetic field effects on crystal growth Magnetic processing of materials Diamagnetic levitation Magneto-Archimedes effect Spin chemistry Application of magnetic fields to analytical chemistry Magnetic orientation Control of structure by magnetic fields Magnetic separation and purification Magnetic field-induced phase transitions Materials properties in high magnetic fields Development of NMR and MRI Medical application of magnetic fields Novel magnetic phenomena Physical property measurement by Magnetic fields High magnetic field generation> MAP3 consisted of 84 presentations including 16 invited talks. This volume of Journal of Physics: Conference Series contains the proceeding of MAP3 with 34 papers that provide a scientific record of the topics covered by the conference with the special topics (13 papers) in

  2. Tilted Magnetic Levitation Enables Measurement of the Complete Range of Densities of Materials with Low Magnetic Permeability.

    Science.gov (United States)

    Nemiroski, Alex; Soh, Siowling; Kwok, Sen Wai; Yu, Hai-Dong; Whitesides, George M

    2016-02-03

    Magnetic levitation (MagLev) of diamagnetic or weakly paramagnetic materials suspended in a paramagnetic solution in a magnetic field gradient provides a simple method to measure the density of small samples of solids or liquids. One major limitation of this method, thus far, has been an inability to measure or manipulate materials outside of a narrow range of densities (0.8 g/cm(3) levitated magnetically. Tilting the MagLev device relative to the gravitational vector enables the magnetic force to be decreased (relative to the magnetic force) along the axis of measurement. This approach enables many practical measurements over the entire range of densities observed in matter at ambient conditions-from air bubbles (ρ ≈ 0) to osmium and iridium (ρ ≈ 23 g/cm(3)). The ability to levitate, simultaneously, objects with a broad range of different densities provides an operationally simple method that may find application to forensic science (e.g., for identifying the composition of miscellaneous objects or powders), industrial manufacturing (e.g., for quality control of parts), or resource-limited settings (e.g., for identifying and separating small particles of metals and alloys).

  3. Nano-magnetic particles used in biomedicine: core and coating materials.

    Science.gov (United States)

    Karimi, Z; Karimi, L; Shokrollahi, H

    2013-07-01

    Magnetic nanoparticles for medical applications have been developed by many researchers. Separation, immunoassay, drug delivery, magnetic resonance imaging and hyperthermia are enhanced by the use of suitable magnetic nanoparticles and coating materials in the form of ferrofluids. Due to their low biocompatibility and low dispersion in water solutions, nanoparticles that are used for biomedical applications require surface treatment. Various kinds of coating materials including organic materials (polymers), inorganic metals (gold, platinum) or metal oxides (aluminum oxide, cobalt oxide) have been attracted during the last few years. Based on the recent advances and the importance of nanomedicine in human life, this paper attempts to give a brief summary on the different ferrite nano-magnetic particles and coatings used in nanomedicine. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Modeling Overlapping Laminations in Magnetic Core Materials Using 2-D Finite-Element Analysis

    DEFF Research Database (Denmark)

    Jensen, Bogi Bech; Guest, Emerson David; Mecrow, Barrie C.

    2015-01-01

    This paper describes a technique for modeling overlapping laminations in magnetic core materials using two-dimensional finite-element (2-D FE) analysis. The magnetizing characteristic of the overlapping region is captured using a simple 2-D FE model of the periodic overlapping geometry...... and a composite material is created, which has the same magnetization characteristic. The benefit of this technique is that it allows a designer to perform design and optimization of magnetic cores with overlapped laminations using a 2-D FE model rather than a 3-D FE model, which saves modeling and simulation...... time. The modeling technique is verified experimentally by creating a composite material of a lap joint with a 3-mm overlapping region and using it in a 2-D FE model of a ring sample made up of a stack of 20 laminations. The B-H curve of the simulated ring sample is compared with the B-H curve obtained...

  5. Straintronics-based magnetic tunneling junction: Dynamic and static behavior analysis and material investigation

    Science.gov (United States)

    Barangi, Mahmood; Mazumder, Pinaki

    2014-04-01

    We theoretically study the dynamic and static effects of mechanical stress on a straintronics device that includes a piezoelectric film combined with a magnetic tunneling junction. The inverse magnetostriction effect is studied in detail by realizing the varying magnetic susceptibility of the nanomagnet under stress. A dynamic model is developed based on the Landau-Lifshitz-Gilbert (LLG) equation, which provides a platform to simulate the magnetization vector's behavior, critical flipping voltage, and delay properties. Furthermore, by converting the LLG equation into a 2nd order damping differential equation, we develop a proximate approach. This approach predicts the dynamic behavior of the magnetization vector and its dependency on material properties and applied voltage across the device without using sophisticated numerical calculations of the LLG model. Different dynamic and static material properties are observed by simulating five common magnetostrictive materials, including a newly discovered alloy, Galfenol.

  6. Magnetic materials and devices for the 21st century: stronger, lighter, and more energy efficient.

    Science.gov (United States)

    Gutfleisch, Oliver; Willard, Matthew A; Brück, Ekkes; Chen, Christina H; Sankar, S G; Liu, J Ping

    2011-02-15

    A new energy paradigm, consisting of greater reliance on renewable energy sources and increased concern for energy efficiency in the total energy lifecycle, has accelerated research into energy-related technologies. Due to their ubiquity, magnetic materials play an important role in improving the efficiency and performance of devices in electric power generation, conditioning, conversion, transportation, and other energy-use sectors of the economy. This review focuses on the state-of-the-art hard and soft magnets and magnetocaloric materials, with an emphasis on their optimization for energy applications. Specifically, the impact of hard magnets on electric motor and transportation technologies, of soft magnetic materials on electricity generation and conversion technologies, and of magnetocaloric materials for refrigeration technologies, are discussed. The synthesis, characterization, and property evaluation of the materials, with an emphasis on structure-property relationships, are discussed in the context of their respective markets, as well as their potential impact on energy efficiency. Finally, considering future bottlenecks in raw materials, options for the recycling of rare-earth intermetallics for hard magnets will be discussed. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Experimental results for a magnetic refrigerator using three different types of magnetocaloric material regenerators

    DEFF Research Database (Denmark)

    Engelbrecht, Kurt; Bahl, Christian Robert Haffenden; Nielsen, Kaspar Kirstein

    2011-01-01

    family were compared. In an attempt to improve system performance, graded two-material regenerators were made from two different combinations of La(Fe,Co,Si)13 compounds having different magnetic transition temperatures. One combination of the La(Fe,Co,Si)13 materials yielded a higher performance, while...

  8. [Investigation of superconductivity and magnetism in d and f-electron materials

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1993-12-31

    Emphasis has been on high {Tc} cuprate susperconductors, along with some experiments on heavy fermion materials. Approach involved the preparation of novel materials, including high {Tc} oxide and rare earth and uranium intermetallic compounds in polycrystals and single crystals, and the investigation of transport, thermal, and magnetic properties of these materials down to 50 mK, in magnetic fields up to 10 tesla, and pressures up to 160 kbar. Other measurements, such as neutron scattering, {mu}SR, and photoemission, are carried out at national facilities.

  9. Development of magnetic materials for continuous ADR system; Uchu yo ADR jiseitai no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Numazawa, T.; Sato, A. [National Research Inst. of Metals, Tokyo (Japan); Arai, O. [Tokyo Inst. of Tech., Tokyo (Japan); Canavan, E.; Shirron, P.

    2000-05-29

    Next generation high resolution light quantum detector using micro-calorimeter such as XRS analyzing equipment mounted on Astro-E is at present under development. For these sensors, ultra-low temperature environment below 100 mK is indispensable, and a cooling system capable of generating ultra-low temperature under no coolant and no gravity is desired. This time, the Metallic Materials Research Institute participated in the development program of ADR for space proceeding in GSFC requested by NASA/Goddard space flight Center (GSFC). The feature of this cooling system is that magnetic materials are divided into multiple bodies in order to generate continuously 50 mK for realization of Carnot cycle. Ferric alum is used for lowest temperature generating magnetic material unit and use of DGGG magnetic material is under examination above 1 K. (NEDO)

  10. Preparation of hard magnetic materials in thin film form

    Energy Technology Data Exchange (ETDEWEB)

    Pigazo, F.; Palomares, F.J. [Instituto de Ciencia de Materiales de Madrid-CSIC, c/ Sor Juana Ines de la Cruz 3, 28049 Madrid (Spain); Cebollada, F. [EUITT-UPM, Carretera de Valencia km 7, 28031 Madrid (Spain); Gonzalez, J.M. [Unidad Asociada ICMM-IMA, c/ Sor Juana Ines de la Cruz 3, 28049 Madrid (Spain)], E-mail: jesus.m.gonzalez@icmm.csic.es

    2008-07-15

    We report on the preparation, by means of pulsed laser ablation deposition, of trilayers of nominal composition Cr/SmCo{sub 5}/Cr//Si with thicknesses in the order of 250/240/125 nm, respectively. According to the results of the structural, chemical and magnetic characterizations performed in our as-deposited samples, the Sm-Co layer was structurally amorphous, exhibited abrupt compositional interfaces with the capping and buffering layers, and coercivities of a few hundreds of Oe. Magnetic hardness was developed upon submitting the samples to current anneals under vacuum at temperatures in the range of 540-670 deg. C. The hardening process was followed in detail by correlating the phase distribution, the nature of the interlayer atomic diffusion processes, the occurrence of textures and the temperature dependence of the coercive force. From our results we conclude about (i) the occurrence of a large degree of Co diffusion/segregation, which results in the detection, from the diffraction and magnetometric results, of the presence of CoCr alloys in the treated samples, and (ii) the close correlation, evidenced from the fits of the temperature dependence of the coercive force to the micromagnetic model, between the coercivity optimization and the crystallinity enhancement of the SmCo{sub 5} grains.

  11. Magnetism of aniline modified graphene-based materials

    Energy Technology Data Exchange (ETDEWEB)

    Komlev, A.A., E-mail: KomlevAnton@hotmail.com [St. Petersburg State Electrotechnical University, St. Petersburg, 197376 (Russian Federation); Lappeenranta University of Technology, 53851 Lappeenranta (Finland); Makarova, T.L. [St. Petersburg State Electrotechnical University, St. Petersburg, 197376 (Russian Federation); Ioffe Physico-Technical Institute, 194021 St. Petersburg (Russian Federation); Lahderanta, E. [St. Petersburg State Electrotechnical University, St. Petersburg, 197376 (Russian Federation); Semenikhin, P.V.; Veinger, A.I.; Tisnek, T.V. [Ioffe Physico-Technical Institute, 194021 St. Petersburg (Russian Federation); Magnani, G. [Università degli studi di Parma, Dipartimento di Fisica e Scienze della Terra, 43124 Parma (Italy); Bertoni, G. [Istituto dei Materiali per l’Elettronica e il Magnetismo(IMEM-CNR), 43124 Parma (Italy); Pontiroli, D.; Ricco, M. [Università degli studi di Parma, Dipartimento di Fisica e Scienze della Terra, 43124 Parma (Italy)

    2016-10-01

    The possibility of producing magnetic graphene nanostructures by functionalization with aromatic radicals has been investigated. Functionalization of graphene basal plane was performed with three types of anilines: 4-bromoaniline, 4-nitroaniline and 4-chloroaniline. The samples were examined by composition analysis with energy-dispersive X-ray spectroscopy and magnetic measurements by SQUID magnetometry and electron paramagnetic resonance. Initial graphene was produced by thermal exfoliation. Both pristine and functionalized samples demonstrate strong paramagnetic contribution at low temperatures, which originates from intrinsic defects. Attachment of an organic molecule with the formation of a covalent bond with carbon atom on the basal plane generates a delocalized spin in the graphene π – electron system. Nitroaniline proved to be the most suitable and sufficiently reactive to attach to the basal plane carbon atoms in large amounts. Functionalization of graphene with nitroaniline resulted in appearance both ferromagnetic and antiferromagnetic features with a clear antiferromagnetic transition near 120 K. - Highlights: • Graphene was produced and functionalized by chloro-, bromo- and nitroaniline. • Nitroaniline was found to be the most suitable compound for functionalization. • Both SQUID and EPR revealed a carbon-related antiferromagnetic transition near 120 K. • Antiferomagnetic interactions are attributed to the extended defects on basal plane.

  12. Preparation and evaluation of magnetic carbonaceous materials for pesticide and metal removal.

    Science.gov (United States)

    Ohno, Masaki; Hayashi, Hiroki; Suzuki, Kazuyuki; Kose, Tomohiro; Asada, Takashi; Kawata, Kuniaki

    2011-07-15

    Magnetic carbonaceous materials were produced by carbonization of a cation exchange resin loaded with ferrous or ferric iron and activation using sieved oyster shell as the activation agent. The magnetic carbonaceous material with the maximum magnetic flux density on every axis (ESS-1) was obtained from the ferric-loaded resin by carbonization at 700°C, followed by activation with the oyster shell at 900°C, and magnetization. A separate step of carbonization and activation appears to cause more of a reduction reaction of Fe to form γ-Fe(2)O(3). The Fe compound in the magnetic carbonaceous material was identified from the XRD pattern as mainly γ-Fe(2)O(3). The magnetic flux density on every axis increased linearly as the amount of the oyster shell increased. Moreover, the adsorption ability of the products was evaluated for pesticides and metal ions. Both ESS-1 and a carbonaceous material obtained from the resin without ferric ion (RC) appear to have the highest adsorption ability for lead. Furthermore, the adsorption ability of ESS-1 might decrease by blockages of the pores with the loaded Fe compounds. Copyright © 2011 Elsevier Inc. All rights reserved.

  13. Nonlinear Magnetic Phenomena in Highly Polarized Target Materials

    CERN Document Server

    Kiselev, Yu F

    2007-01-01

    The report introduces and surveys nonlinear magnetic phenomena which have been observed at high nuclear polarizations in polarized targets of the SMC and of the COMPASS collaborations at CERN. Some of these phenomena, namely the frequency modulation eect and the distortion of the NMR line shape, promote the development of the polarized target technique. Others, as the spin-spin cross-relaxation between spin subsystems can be used for the development of quantum statistical physics. New findings bear on an electromagnetic noise and the spectrally resolved radiation from LiD with negatively polarized nuclei detected by low temperature bolometers. These nonlinear phenomena need to be taken into account for achieving the ultimate polarizations.

  14. Boronic acid-modified magnetic materials for antibody purification.

    Science.gov (United States)

    Dhadge, Vijaykumar L; Hussain, Abid; Azevedo, Ana M; Aires-Barros, Raquel; Roque, Ana C A

    2014-02-06

    Aminophenyl boronic acids can form reversible covalent ester interactions with cis-diol-containing molecules, serving as a selective tool for binding glycoproteins as antibody molecules that possess oligosaccharides in both the Fv and Fc regions. In this study, amino phenyl boronic acid (APBA) magnetic particles (MPs) were applied for the magnetic separation of antibody molecules. Iron oxide MPs were firstly coated with dextran to avoid non-specific binding and then with 3-glycidyloxypropyl trimethoxysilane to allow further covalent coupling of APBA (APBA_MP). When contacted with pure protein solutions of human IgG (hIgG) and bovine serum albumin (BSA), APBA_MP bound 170 ± 10 mg hIgG g(-1) MP and eluted 160 ± 5 mg hIgG g(-1) MP, while binding only 15 ± 5 mg BSA g(-1) MP. The affinity constant for the interaction between hIgG and APBA_MP was estimated as 4.9 × 10(5) M(-1) (Ka) with a theoretical maximum capacity of 492 mg hIgG adsorbed g(-1) MP (Qmax), whereas control particles bound a negligible amount of hIgG and presented an estimated theoretical maximum capacity of 3.1 mg hIgG adsorbed g(-1) MP (Qmax). APBA_MPs were also tested for antibody purification directly from CHO cell supernatants. The particles were able to bind 98% of IgG loaded and to recover 95% of pure IgG (purity greater than 98%) at extremely mild conditions.

  15. Investigation of alternative materials for impregnation of $Nb_{3}$ Sn magnets

    CERN Document Server

    Chichili, D R; Zlobin, A V

    2003-01-01

    Insulation is one of the most important elements of magnet design, which determines the electrical, mechanical, and thermal performance as well as lifetime of the magnet. The exposure to high radiation loads especially for the proposed LHC second-generation interaction region Nb/sub 3/Sn quadrupoles further limits the choices of the insulation materials. Traditionally Nb/sub 3/Sn magnets were impregnated with epoxy to improve both the mechanical and electrical properties. However, the acceptable radiation limit for epoxy is low which reduces the lifetime of the magnet. The paper presents the results of the feasibility study to replace epoxy with high radiation-resistant material during vacuum impregnation. The mechanical, thermal and electrical properties of samples impregnated with Matrimid were measured and compared with epoxy-impregnated samples. (9 refs).

  16. Magnetic susceptibility and electrical conductivity of metallic dental materials and their impact on MR imaging artifacts.

    Science.gov (United States)

    Starcuková, Jana; Starcuk, Zenon; Hubálková, Hana; Linetskiy, Igor

    2008-06-01

    The aim of this study was to test the hypothesis that dental materials vary significantly in MR-relevant material parameters-magnetic susceptibility and electrical conductivity, and that knowledge of these parameters may be used to estimate the quality of MR imaging in the presence of devices made of such materials. Magnetic susceptibility, electrical conductivity and artifacts were evaluated for 45 standardized cylindrical samples of dental alloys and amalgams. Magnetic susceptibility was determined by fitting the phase of gradient-echo MR images to numerically modeled data. Electrical conductivity was determined by standard electrotechnical measurements. Artifact sizes were measured in spin-echo (SE) and gradient-echo (GE) images at 1.5T according to the standards of the American Society for Testing and Materials. It has been confirmed that dental materials differ considerably in their magnetic susceptibility, electrical conductivity and artifacts. For typical dental devices, magnetic susceptibility differences were found of little clinical importance for diagnostic SE/GE imaging of the neck and brain, but significant for orofacial imaging. Short-TE GE imaging has been found possible even in very close distances from dental devices made of amalgams, precious alloys and titanium alloys. Nickel-chromium and cobalt-chromium artifacts were found still acceptable, but large restorations of aluminum bronzes may preclude imaging of the orofacial region. The influence of electrical conductivity on the artifact size was found negligible. MR imaging is possible even close to dental devices if they are made of dental materials with low magnetic susceptibility. Not all materials in current use meet this requirement.

  17. Magnetism in atomically thin quasi two-dimensional materials: Renormalized spin wave theory

    Science.gov (United States)

    Li, Zhenglu; Cao, Ting; Louie, Steven G.

    In this work, we apply renormalized spin wave theory to the magnetic behavior of atomically thin two-dimensional crystals. We find that magnon-magnon interaction plays an important role in renormalizing the magnetic transition temperature, and the magnetic behavior is largely dependent on the magnetic anisotropy and the thickness of the crystal in the two-dimensional limit. Our method is applicable to general magnetic crystals with input spin interaction parameters mapped out from either ab initio calculations or extracted from experiments. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, and by the National Science Foundation. Computational resources have been provided by NERSC and XSEDE.

  18. Effect of electrically insulating materials on magnetically induced electrical currents in a tissue-like medium

    Science.gov (United States)

    Hoffmeister, Brent K.; Shores, Andrew R.; Banerjee, Shubho; Malkin, Robert A.

    2006-04-01

    Time varying magnetic fields can induce eddy currents in a conductor. Electrical currents also can be induced magnetically in the human body, and there has been considerable interest in the bioeffects of this phenomenon. We present an analytical model derived from Faraday's law and Coulomb's law that provides physical insight into how electrically insulating materials in a tissue-like medium redirect magnetically induced currents. The model shows that charge accumulates at the tissue-insulator interface to produce a secondary electric field. This field combines with the magnetically induced electric field to alter the net electric field in the vicinity of the insulator, causing the electric current to flow around the insulator. The model is supplemented by measurements of magnetically induced electric fields in a volume of physiologic saline solution. Good agreement is found among the model, the measurements, and a finite element analysis model of the experiment.

  19. Skyrmion lattice in a magnetic film with spatially modulated material parameters

    Energy Technology Data Exchange (ETDEWEB)

    Sapozhnikov, M.V., E-mail: msap@ipmras.ru [Institute for Physics of Microstructures, RAS, Nizhny Novgorod 603950, GSP-105 (Russian Federation); N.I. Lobachevskii State University, Nizhny Novgorod 603950 (Russian Federation)

    2015-12-15

    The problem of the skyrmion stability in the magnetic film with perpendicular anisotropy inside the area with the changed material parameters is considered. The solution describing the conditions of such stabilization in the absence of Dzyaloshinskii–Moriya interaction is obtained analytically. The easy method of nanomodification of ordinary magnetic perpendicular media such as Co,Fe/Pt,Pd,Ru superlattices allowing the formation of the dense enough (with the period less than 100 nm) skyrmion lattices is suggested. By micromagnetic simulations it is shown that the skyrmion lattices can be initialized in the system by simple magnetization in the uniform external magnetic field. - Highlights: • The conditions of skyrmion stability in magnetic films are analytically calculated. • The skyrmion lattice initializing by the uniform field is numerically simulated. • The nanopatterning method to obtain high skyrmion density is suggested.

  20. Influence of Thermal Treatment on Magnetic Properties of Steel Sheet Material Utilised in Cable Routing System

    Directory of Open Access Journals (Sweden)

    Elemir Usak

    2013-01-01

    Full Text Available The influence of relax annealing aimed at removal of the residual stresses (so-called stress-relief annealing on various magnetic parameters, such as the relative magnetic amplitude permeability, coercivity, remanent flux density, etc. is discussed. Samples of steel cable tray material which is a part of commercially available cable routing system were investigated in order to find information about the properties important from the point of view of EMC requirements in extremely demanding industrial environment.

  1. Inductive heating with magnetic materials inside flow reactors.

    Science.gov (United States)

    Ceylan, Sascha; Coutable, Ludovic; Wegner, Jens; Kirschning, Andreas

    2011-02-07

    Superparamagnetic nanoparticles coated with silica gel or alternatively steel beads are new fixed-bed materials for flow reactors that efficiently heat reaction mixtures in an inductive field under flow conditions. The scope and limitations of these novel heating materials are investigated in comparison with conventional and microwave heating. The results suggest that inductive heating can be compared to microwave heating with respect to rate acceleration. It is also demonstrated that a very large diversity of different reactions can be performed under flow conditions by using inductively heated flow reactors. These include transfer hydrogenations, heterocyclic condensations, pericyclic reactions, organometallic reactions, multicomponent reactions, reductive cyclizations, homogeneous and heterogeneous transition-metal catalysis. Silica-coated iron oxide nanoparticles are stable under many chemical conditions and the silica shell could be utilized for further functionalization with Pd nanoparticles, rendering catalytically active heatable iron oxide particles. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Iron losses evaluation in soft magnetic materials with a sinusoidal voltage supply

    DEFF Research Database (Denmark)

    Nedelcu, Steluţa; Ritchie, Ewen; Leban, Krisztina Monika

    2013-01-01

    and it is proposing an identification procedure for the model coefficients from multi-frequency single sheet tests. The frequencies used are in the range 10 Hz and 150 Hz and with the values of magnetic flux density in the range 0.1 T and 1.4 T. The model was applied on six magnetic materials of different thicknesses...... (between 0.35 mm and 0.65 mm) and alloy compositions. Hysteresis and eddy currents loss coefficients have been considered as dependent on the frequency. For curve fitting of these coefficients third and fourth polynomials were employed, with good result for all the frequencies and magnetic flux density...

  3. Full-Vector, Low-Temperature Magnetic Measurements of Geologic Materials

    Science.gov (United States)

    Feinberg, J.; Sølheid, P.; Bowles, J. A.; Jackson, M. J.; Moskowitz, B. M.

    2010-12-01

    The magnetic properties of geologic materials offer insights into an enormous range of important geophysical phenomena ranging from core dynamics to paleoclimate. Low-temperature (pulse magnetizers. Used in conjunction with the in-line degausser on the IRM’s pass-through magnetometer, it will ultimately be possible to acquire anhysteretic remanence (ARM) and/or AF demagnetize samples at cryogenic temperatures. The intent of this presentation is to advertise the capabilities of the cryogenic insert and to encourage members of the rock magnetic community to plan on using the instrument to further their own research.

  4. Spin and Charge Transport in 2D Materials and Magnetic Insulator/Metal Heterostructures

    Science.gov (United States)

    Amamou, Walid

    Spintronic devices are very promising for future information storage, logic operations and computation and have the potential to replace current CMOS technology approaching the scaling limit. In particular, the generation and manipulation of spin current enables the integration of storage and logic within the same circuit for more powerful computing architectures. In this thesis, we examine the manipulation of spins in 2D materials such as graphene and metal/magnetic insulator heterostructures. In particular, we investigate the feasibility for achieving magnetization switching of a nanomagnet using graphene as a nonmagnetic channel material for All Spin Logic Device applications. Using in-situ MBE deposition of nanomagnet on graphene spin valve, we demonstrate the presence of an interfacial spin dephasing at the interface between the graphene and the nanomagnet. By introducing a Cu spacer between the nanomagnet and graphene, we demonstrate that this interfacial effect is related to an exchange interaction between the spin current and the disordered magnetic moment of the nanomagnet in the first monolayer. In addition to the newly discovered interfacial spin relaxation effect, the extracted contact resistance area product of the nanomagnet/graphene interface is relatively high on the order of 1Omicrom2. In practice, reducing the contact resistance will be as important as eliminating the interfacial relaxation in order to achieve magnetization switching. Furthermore, we examine spin manipulation in a nonmagnetic Pt using an internal magnetic exchange field produced by the adjacent magnetic insulator CoFe2O4 grown by MBE. Here, we report the observation of a strong magnetic proximity effect of Pt deposited on top of a perpendicular magnetic anisotropy (PMA) inverse spinel material Cobalt Ferrite (CFO, CoFe 2O4). The CFO was grown by MBE and its magnetization was characterized by Vibrating Sample Magnetometry (VSM) demonstrating the strong out of plane magnetic

  5. Mechanical alloying of Fe?Ni based nanostructured magnetic materials

    Science.gov (United States)

    Du, S. W.; Ramanujan, R. V.

    2005-04-01

    Alloys with the composition Fe 40Ni 38B 18Mo 4, Fe 49Ni 46Mo 5 and Fe 42Ni 40B 18 were processed from elemental powders by mechanical alloying and the microstructure was studied by differential scanning calorimetry (DSC), X-ray diffractometer (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. Nanocrystalline fcc solid solution was achieved as a result of mechanical alloying in all three alloy compositions and the grain size reduced to nanoscale but lattice strain was introduced. Molybdenum was found to affect the products of mechanical alloying, specifically, the Fe 3B phase formed in the Fe 42Ni 40B 18 alloy while no boride phase formed in the Fe 40Ni 38B 18Mo 4 alloy. SEM studies indicated that the presence of boron was found to make the milling process easier. Elemental mapping by SEM as well as XRD results showed that molybdenum does not dissolve easily in the Fe-Ni solid solution produced by milling. The DSC results suggested that an amorphous structure together with nanocrystals was obtained in the Fe 40Ni 38B 18Mo 4 and Fe 42Ni 40B 18 alloys. A two-stage crystallization process was found in the Fe 40Ni 38B 18Mo 4 and Fe 42Ni 40B 18 alloys, the presence of boron was found to make amorphization easier. TEM investigations were consistent with these XRD and DSC results. Heat-treated samples of the Fe 40Ni 38B 18Mo 4 and Fe 42Ni 40B 18 alloys milled for 100 h showed that molybdenum inhibited the grain growth. The saturation magnetization of the heat-treated Fe 40Ni 38B 18Mo 4 alloy milled for 100 h was stable, coercivity was reduced; on the other hand, the Ms of heat-treated Fe 42Ni 40B 18 alloy milled for 100 h decreased and the Hc increased. This difference in magnetic behavior is due to the alloying addition of molybdenum which affected the microstructural evolution during heat treatment, specifically by inhibition of the increase in grain size.

  6. Electronic states in systems of reduced dimensionality. Progress report, September 15, 1991--September 14, 1992

    Energy Technology Data Exchange (ETDEWEB)

    Ulloa, S.E.

    1992-04-15

    This report briefly discusses the following research: magnetically modulated systems, inelastic magnetotunneling, ballistic transport review, screening in reduced dimensions, raman and electron energy loss spectroscopy; and ballistic quantum interference effects. (LSP).

  7. Mechanical alloying of Fe-Ni based nanostructured magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Du, S.W. [School of Materials Engineering, Nanyang Technological University, B1k N4.1, Nanyang Ave., Singapore 639798 (Singapore); Ramanujan, R.V. [School of Materials Engineering, Nanyang Technological University, B1k N4.1, Nanyang Ave., Singapore 639798 (Singapore)]. E-mail: ramanujan@ntu.edu.sg

    2005-04-15

    Alloys with the composition Fe{sub 40}Ni{sub 38}B{sub 18}Mo{sub 4}, Fe{sub 49}Ni{sub 46}Mo{sub 5} and Fe{sub 42}Ni{sub 40}B{sub 18} were processed from elemental powders by mechanical alloying and the microstructure was studied by differential scanning calorimetry (DSC), X-ray diffractometer (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. Nanocrystalline fcc solid solution was achieved as a result of mechanical alloying in all three alloy compositions and the grain size reduced to nanoscale but lattice strain was introduced. Molybdenum was found to affect the products of mechanical alloying, specifically, the Fe{sub 3}B phase formed in the Fe{sub 42}Ni{sub 40}B{sub 18} alloy while no boride phase formed in the Fe{sub 40}Ni{sub 38}B{sub 18}Mo{sub 4} alloy. SEM studies indicated that the presence of boron was found to make the milling process easier. Elemental mapping by SEM as well as XRD results showed that molybdenum does not dissolve easily in the Fe-Ni solid solution produced by milling. The DSC results suggested that an amorphous structure together with nanocrystals was obtained in the Fe{sub 40}Ni{sub 38}B{sub 18}Mo{sub 4} and Fe{sub 42}Ni{sub 40}B{sub 18} alloys. A two-stage crystallization process was found in the Fe{sub 40}Ni{sub 38}B{sub 18}Mo{sub 4} and Fe{sub 42}Ni{sub 40}B{sub 18} alloys, the presence of boron was found to make amorphization easier. TEM investigations were consistent with these XRD and DSC results. Heat-treated samples of the Fe{sub 40}Ni{sub 38}B{sub 18}Mo{sub 4} and Fe{sub 42}Ni{sub 40}B{sub 18} alloys milled for 100 h showed that molybdenum inhibited the grain growth. The saturation magnetization of the heat-treated Fe{sub 40}Ni{sub 38}B{sub 18}Mo{sub 4} alloy milled for 100 h was stable, coercivity was reduced; on the other hand, the M {sub s} of heat-treated Fe{sub 42}Ni{sub 40}B{sub 18} alloy milled for 100 h decreased and the H {sub c} increased. This difference in magnetic

  8. Evaluation of Core Loss in Magnetic Materials Employed in Utility Grid AC Filters

    DEFF Research Database (Denmark)

    Beres, Remus Narcis; Wang, Xiongfei; Blaabjerg, Frede

    2016-01-01

    in the core, depending on the magnetic material of choice and current ripple specifications. Additionally, shunt or series reactors that exists in LCL or trap filters and which are subjected to sinusoidal excitations have different specifications and requirements. Therefore, the core losses of different...... magnetic materials adopted in utility grid ac filters have been investigated and measured for both sinusoidal and rectangular excitation, with and without dc bias condition. The core loss information can ensure cost effective passive filter designs and may avoid trial-error design procedures of the passive...

  9. Factors affecting coercivity in rare-earth based advanced permanent magnet materials

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, L.H. [Brookhaven National Lab., Upton, NY (United States); Sellers, C.H. [Lockheed Idaho Technologies Co., Idaho Falls, ID (United States); Panchanathan, V. [Magnequench International, Inc., Anderson, IN (United States)

    1997-02-01

    The relationships that link microstructural properties of advanced permanent magnet materials with magnetic properties such as the coercivity are often difficult to quantify, especially in materials with nano-scale structures. Recent work on RE{sub 2}Fe{sub 14}B-based powders fabricated with rapid-solidification techniques such as inert gas atomization (IGA) and melt-spinning provide insight into the nanostructural features which affect the acquisition and stability of coercivity. In all cases the coercivity is found to be a function of both the scale of the constituent microstructure and of the presence and distribution of minor phases.

  10. Ferromagnetism modulation by phase change in Mn-doped GeTe chalcogenide magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Adam, Adam Abdalla Elbashir [Huazhong University of Science and Technology, School of Optical and Electronic Information, Wuhan (China); Wuhan National Laboratory for Optoelectronics, Wuhan (China); Alneelain University, Faculty of Science and Technology, Khartoum (Sudan); Cheng, Xiaomin; Guan, Xiawei; Miao, Xiangshui [Huazhong University of Science and Technology, School of Optical and Electronic Information, Wuhan (China); Wuhan National Laboratory for Optoelectronics, Wuhan (China)

    2014-12-15

    In this work, an effective method to modulate the ferromagnetic properties of Mn-doped GeTe chalcogenide-based phase change materials is presented. The microstructure of the phase change magnetic material Ge{sub 1-x} Mn{sub x} Te thin films was studied. The X-ray diffraction results demonstrate that the as-deposited films are amorphous, and the crystalline films are formed after annealing at 350 C for 10 min. Crystallographic structure investigation shows the existence of some secondary magnetic phases. The lattice parameters of Ge{sub 1-x} Mn{sub x} Te (x = 0.04, 0.12 and 0.15) thin films are found to be slightly different with changes of Mn compositions. The structural analysis clearly indicates that all the films have a stable rhombohedral face-centered cubic polycrystalline structure. The magnetic properties of the amorphous and crystalline Ge{sub 0.96}Mn{sub 0.04}Te were investigated. The measurements of magnetization (M) as a function of the magnetic field (H) show that both amorphous and crystalline phases of Ge{sub 0.96}Mn{sub 0.04}Te thin film are ferromagnetic and there is drastic variation between amorphous and crystalline states. The temperature (T) dependence of magnetizations at zero field cooling (ZFC) and field cooling (FC) conditions of the crystalline Ge{sub 0.96}Mn{sub 0.04}Te thin film under different applied magnetic fields were performed. The measured data at 100 and 300 Oe applied magnetic fields show large bifurcations in the ZFC and FC curves while on the 5,000 Oe magnetic field there is no deviation. (orig.)

  11. Alluaudite class of high voltage sodium insertion materials: An interplay of polymorphism and magnetism

    Science.gov (United States)

    Dwibedi, Debasmita; Barpanda, Prabeer

    2017-05-01

    The research and development with sodium ion batteries has geared up manifold in last one decade, owing to their abundance, non-toxicity, uniform geographical distribution and electrochemical performance complimentary to lithium counterpart. This research often leads to various novel material discoveries such as Na2Fe2(SO4)3 sodium insertion material, which has recently registered the highest-ever Fe3+/Fe2+ redox potential (3.8 V vs. Na) having excellent cyclability and rate kinetics. This basically belongs to a family of materials-Alluaudites Na2M2(SO4)3 (M: Fe, Mn, Co, Ni). Such cathode insertion compounds are basically functional materials, involving redox active 3d transition metals that are often magnetic in nature. We have investigated the magnetic structure and properties of - Alluaudites Na2M2(SO4)3. These alluaudite shows wide structural diversity and polymorphism. Employing various experimental methods involving diffraction, magnetic susceptibility, Mössbauer spectroscopy and low temperature neutron powder diffraction data we have explored the magnetic properties exhibited by the Alluaudite class of insertion materials.

  12. Implementation of Cavity Perturbation Method for Determining Relative Permittivity of Non Magnetic Materials

    Directory of Open Access Journals (Sweden)

    FAHIM GOHARAWAN

    2017-04-01

    Full Text Available Techniques for the cavity measurement of the electrical characteristics of the materials are well established using the approximate method due to its simplicity in material insertion and fabrication. However, the exact method which requires more comprehensive mathematical analysis as well, owing to the practical difficulties for the material insertion, is not mostly used while performing the measurements as compared to approximate method in most of the works. In this work the comparative analysis of both the approximate as well as Exact method is performed and accuracy of the Exact method is established by performing the measurements of non-magnetic material Teflon within the cavity.

  13. Data mining for materials design: A computational study of single molecule magnet

    Energy Technology Data Exchange (ETDEWEB)

    Dam, Hieu Chi [Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Faculty of Physics, Vietnam National University, 334 Nguyen Trai, Hanoi (Viet Nam); Pham, Tien Lam; Ho, Tu Bao [Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Nguyen, Anh Tuan [Faculty of Physics, Vietnam National University, 334 Nguyen Trai, Hanoi (Viet Nam); Nguyen, Viet Cuong [HPC Systems, Inc., 3-9-15 Kaigan, Minato-ku, Tokyo 108-0022 (Japan)

    2014-01-28

    We develop a method that combines data mining and first principles calculation to guide the designing of distorted cubane Mn{sup 4+} Mn {sub 3}{sup 3+} single molecule magnets. The essential idea of the method is a process consisting of sparse regressions and cross-validation for analyzing calculated data of the materials. The method allows us to demonstrate that the exchange coupling between Mn{sup 4+} and Mn{sup 3+} ions can be predicted from the electronegativities of constituent ligands and the structural features of the molecule by a linear regression model with high accuracy. The relations between the structural features and magnetic properties of the materials are quantitatively and consistently evaluated and presented by a graph. We also discuss the properties of the materials and guide the material design basing on the obtained results.

  14. Materials Development and Spin Transport Study of Magnetic Insulator Based Heterostructures

    Science.gov (United States)

    Tang, Chi

    The subfield of magnetic insulator (MI) based spintronics is playing a substantial role in modern solid state physics research. Spin current in the MI is propagated in spin wave with a much longer decay length than spin-polarized carriers in conducting ferromagnet. In the MI-based hetereostructures, the adjacent non-magnetic materials can be magnetized in proximity of MI. Therefore, it is a promising system to study exotic transport phenomena such as quantum Anomalous Hall effect in topological insulator and graphene. Rare-earth Iron garnet (ReIG), a class of magnetic insulators with large electronic bandgap and high Curie temperature, stands out among various magnetic insulator materials and have attracted a great deal of attention in recent magnetic insulator based spintronics research. The first chapter of this dissertation gives a brief introduction to the spintronics research by introducing some essential concepts in the spintronics field and the most recent spin transport phenomena. The second chapter of this dissertation summarizes my work in the materials development of ReIG ferrimagnetic insulators, including exquisite control of high quality ultra-flat yttrium iron garnet (YIG) thin films with extremely low magnetic damping and engineering of strain induced robust perpendicular magnetic anisotropy in thulium iron garnet (TIG) and Bi-doped YIG films. The last chapter of this dissertation shows a systematic study in various ReIG based heterostructures, mainly divided into groups: ReIG (YIG & TIG)/heavy metal bilayers (Pd & Pt) and ReIG (YIG & TIG)/Dirac systems (graphene & topological insulator). The magneto-transport study disentangles the contribution from a spin current origin and proximity induced magnetism. Furthermore, the demonstration in the proximity coupling induced high-temperature ferromagnetic phase in low-dimensional Dirac systems, i.e. graphene and topological insulator surface states, provides new possibilities in the future spintronics

  15. A study of the dielectric and magnetic properties of multiferroic materials using the Monte Carlo method

    Directory of Open Access Journals (Sweden)

    A. Sosa

    2012-03-01

    Full Text Available A study of the dielectric and magnetic properties of multiferroic materials using the Monte Carlo (MC method is presented. Two different systems are considered: the first, ferroelectric-antiferromagnetic (FE-AFM recently studied by X. S. Gaoand J. M. Liu and the second antiferroelectric-ferromagnetic (AFE-FM. Based on the DIFFOUR-Ising hybrid microscopic model developed by Janssen, a Hamiltonian that takes into account the magnetoelectric coupling in both ferroic phases is proposed. The obtained results show that the existence of such coupling modifies the ferroelectric and magnetic ordering in both phases. Additionally, it is shown that the presence of a magnetic or an electric field influences the electric polarization and the magnetization, respectively, making evident the magnetoelectric effect.

  16. Nuclear magnetic resonance of laser-polarized noble gases in molecules, materials and organisms

    Energy Technology Data Exchange (ETDEWEB)

    Goodson, Boyd McLean [Univ. of California, Berkeley, CA (United States)

    1999-12-01

    Conventional nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) are fundamentally challenged by the insensitivity that stems from the ordinarily low spin polarization achievable in even the strongest NMR magnets. However, by transferring angular momentum from laser light to electronic and nuclear spins, optical pumping methods can increase the nuclear spin polarization of noble gases by several orders of magnitude, thereby greatly enhancing their NMR sensitivity. This dissertation is primarily concerned with the principles and practice of optically pumped nuclear magnetic resonance (OPNMR). The enormous sensitivity enhancement afforded by optical pumping noble gases can be exploited to permit a variety of novel NMR experiments across many disciplines. Many such experiments are reviewed, including the void-space imaging of organisms and materials, NMR and MRI of living tissues, probing structure and dynamics of molecules in solution and on surfaces, and zero-field NMR and MRI.

  17. Magnetic refrigeration at room temperature - from magnetocaloric materials to a prototype

    DEFF Research Database (Denmark)

    Kuhn, Luise Theil; Pryds, Nini; Bahl, Christian Robert Haffenden

    2011-01-01

    materials, their shaping and graded composition for technological use. Modelling the performance of a permanent magnet with optimum use of the flux and relatively low weight, and designing and constructing a prototype continuous magnetic refrigeration device have also been major tasks in the project......Based on the magnetocaloric effect, magnetic refrigeration at room temperature has for the past decade been a promising, environmentally friendly new energy technology predicted to have a significantly higher efficiency than the present conventional methods. However, so far only a few prototype...... refrigeration machines have been presented worldwide and there are still many scientific and technological challenges to be overcome. We report here on the MagCool project, which spans all the way from basic materials studies to the construction of a prototype. Emphasis has been on ceramic magnetocaloric...

  18. Magnetic Nanoparticles: Material Engineering and Emerging Applications in Lithography and Biomedicine

    Science.gov (United States)

    Bao, Yuping; Wen, Tianlong; Samia, Anna Cristina S.; Khandhar, Amit; Krishnan, Kannan M.

    2015-01-01

    We present an interdisciplinary overview of material engineering and emerging applications of iron oxide nanoparticles. We discuss material engineering of nanoparticles in the broadest sense, emphasizing size and shape control, large-area self-assembly, composite/hybrid structures, and surface engineering. This is followed by a discussion of several non-traditional, emerging applications of iron oxide nanoparticles, including nanoparticle lithography, magnetic particle imaging, magnetic guided drug delivery, and positive contrast agents for magnetic resonance imaging. We conclude with a succinct discussion of the pharmacokinetics pathways of iron oxide nanoparticles in the human body –– an important and required practical consideration for any in vivo biomedical application, followed by a brief outlook of the field. PMID:26586919

  19. Requirements for accurate estimation of anisotropic material parameters by magnetic resonance elastography: A computational study.

    Science.gov (United States)

    Tweten, D J; Okamoto, R J; Bayly, P V

    2017-12-01

    To establish the essential requirements for characterization of a transversely isotropic material by magnetic resonance elastography (MRE). Three methods for characterizing nearly incompressible, transversely isotropic (ITI) materials were used to analyze data from closed-form expressions for traveling waves, finite-element (FE) simulations of waves in homogeneous ITI material, and FE simulations of waves in heterogeneous material. Key properties are the complex shear modulus μ2 , shear anisotropy ϕ=μ1/μ2-1, and tensile anisotropy ζ=E1/E2-1. Each method provided good estimates of ITI parameters when both slow and fast shear waves with multiple propagation directions were present. No method gave accurate estimates when the displacement field contained only slow shear waves, only fast shear waves, or waves with only a single propagation direction. Methods based on directional filtering are robust to noise and include explicit checks of propagation and polarization. Curl-based methods led to more accurate estimates in low noise conditions. Parameter estimation in heterogeneous materials is challenging for all methods. Multiple shear waves, both slow and fast, with different propagation directions, must be present in the displacement field for accurate parameter estimates in ITI materials. Experimental design and data analysis can ensure that these requirements are met. Magn Reson Med 78:2360-2372, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  20. In situ nuclear magnetic resonance study of defect dynamics during deformation of materials

    NARCIS (Netherlands)

    Murty, K.L.; Detemple, K.; Kanert, O.; Peters, G; de Hosson, J.T.M.

    1996-01-01

    Nuclear magnetic resonance techniques can be used to monitor in situ the dynamical behaviour of point and line defects in materials during deformation. These techniques are non-destructive and non-invasive. We report here the atomic transport, in particular the enhanced diffusion during deformation

  1. Optical magnetic, and electrical properties of tektites, meteorites, and other space related materials

    Science.gov (United States)

    1974-01-01

    The scope of the project is reported to study the infrared absorption of water and the magnetic properties of the iron in tektites. Subsequently, the work was expanded to include the other properties of tektites and lunar materials. When the lunar samples became available, the emphasis of the research shifted from tektites to lunar samples.

  2. Hybrid wood materials with magnetic anisotropy dictated by the hierarchical cell structure.

    Science.gov (United States)

    Merk, Vivian; Chanana, Munish; Gierlinger, Notburga; Hirt, Ann M; Burgert, Ingo

    2014-06-25

    Anisotropic and hierarchical structures are bound in nature and highly desired in engineered materials, due to their outstanding functions and performance. Mimicking such natural features with synthetic materials and methods has been a highly active area of research in the last decades. Unlike these methods, we use the native biomaterial wood, with its intrinsic anisotropy and hierarchy as a directional scaffold for the incorporation of magnetic nanoparticles inside the wood material. Nanocrystalline iron oxide particles were synthesized in situ via coprecipitation of ferric and ferrous ions within the interconnected pore network of bulk wood. Imaging with low-vacuum and cryogenic electron microscopy as well as spectral Raman mapping revealed layered nanosize particles firmly attached to the inner surface of the wood cell walls. The mineralogy of iron oxide was identified by XRD powder diffraction and Raman spectroscopy as a mixture of the spinel phases magnetite and maghemite. The intrinsic structural architecture of native wood entails a three-dimensional assembly of the colloidal iron oxide which results in direction-dependent magnetic features of the wood-mineral hybrid material. This superinduced magnetic anisotropy, as quantified by direction-dependent magnetic hysteresis loops and low-field susceptibility tensors, allows for directional lift, drag, alignment, (re)orientation, and actuation, and opens up novel applications of the natural resource wood.

  3. Anomalous wave structure in magnetized materials described by non-convex equations of state

    Energy Technology Data Exchange (ETDEWEB)

    Serna, Susana, E-mail: serna@mat.uab.es [Departament de Matematiques, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain); Marquina, Antonio, E-mail: marquina@uv.es [Departamento de Matematicas, Universidad de Valencia, 46100 Burjassot, Valencia (Spain)

    2014-01-15

    We analyze the anomalous wave structure appearing in flow dynamics under the influence of magnetic field in materials described by non-ideal equations of state. We consider the system of magnetohydrodynamics equations closed by a general equation of state (EOS) and propose a complete spectral decomposition of the fluxes that allows us to derive an expression of the nonlinearity factor as the mathematical tool to determine the nature of the wave phenomena. We prove that the possible formation of non-classical wave structure is determined by both the thermodynamic properties of the material and the magnetic field as well as its possible rotation. We demonstrate that phase transitions induced by material properties do not necessarily imply the loss of genuine nonlinearity of the wavefields as is the case in classical hydrodynamics. The analytical expression of the nonlinearity factor allows us to determine the specific amount of magnetic field necessary to prevent formation of complex structure induced by phase transition in the material. We illustrate our analytical approach by considering two non-convex EOS that exhibit phase transitions and anomalous behavior in the evolution. We present numerical experiments validating the analysis performed through a set of one-dimensional Riemann problems. In the examples we show how to determine the appropriate amount of magnetic field in the initial conditions of the Riemann problem to transform a thermodynamic composite wave into a simple nonlinear wave.

  4. Ultra-low field nuclear magnetic resonance and magnetic resonance imaging to discriminate and identify materials

    Science.gov (United States)

    Matlashov, Andrei Nikolaevich; Urbaitis, Algis V.; Savukov, Igor Mykhaylovich; Espy, Michelle A.; Volegov, Petr Lvovich; Kraus, Jr., Robert Henry

    2013-03-05

    Method comprising obtaining an NMR measurement from a sample wherein an ultra-low field NMR system probes the sample and produces the NMR measurement and wherein a sampling temperature, prepolarizing field, and measurement field are known; detecting the NMR measurement by means of inductive coils; analyzing the NMR measurement to obtain at least one measurement feature wherein the measurement feature comprises T1, T2, T1.rho., or the frequency dependence thereof; and, searching for the at least one measurement feature within a database comprising NMR reference data for at least one material to determine if the sample comprises a material of interest.

  5. Hybrid materials: Magnetite-Polyethylenimine-Montmorillonite, as magnetic adsorbents for Cr(VI) water treatment.

    Science.gov (United States)

    Larraza, Iñigo; López-Gónzalez, Mar; Corrales, Teresa; Marcelo, Gema

    2012-11-01

    Hybrid materials formed by the combination of a sodium rich Montmorillonite (MMT), with magnetite nanoparticles (40 nm, Fe(3)O(4) NPs) coated with Polyethylenimine polymer (PEI 800 g/mol or PEI 25000 g/mol) were prepared. The intercalation of the magnetite nanoparticles coated with PEI among MMT platelets was achieved by cationic exchange. The resulting materials presented a high degree of exfoliation of the MMT sheets and a good dispersion of Fe(3)O(4) NPs on both the surface and among the layers of MMT. The presence of amine groups in the PEI structure not only aids the exfoliation of the MMT layers, but also gives to the hybrid material the necessary functionality to interact with heavy metals. These hybrid materials were used as magnetic sorbent for the removal of hexavalent chromium from water. The effect that pH, Cr(VI) concentration, and adsorbent material composition have on the Cr(VI) removal efficiency was studied. A complete characterization of the materials was performed. The hybrid materials showed a slight dependence of the removal efficiency with the pH in a wide range (1-9). A maximum amount of adsorption capacity of 8.8 mg/g was determined by the Langmuir isotherm. Results show that these hybrid materials can be considered as potential magnetic adsorbent for the Cr(VI) removal from water in a wide range of pH. Copyright © 2012 Elsevier Inc. All rights reserved.

  6. {delta}-FeOOH: a superparamagnetic material for controlled heat release under AC magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Chagas, Poliane; Candido da Silva, Adilson [ICEx, Universidade Federal de Minas Gerais, Departamento de Quimica (Brazil); Caetano Passamani, Edson [Universidade Federal do Espirito Santo, Departamento de Fisica (Brazil); Ardisson, Jose Domingos [Centro de Desenvolvimento da Tecnologia Nuclear (Brazil); Alves de Oliveira, Luiz Carlos [ICEx, Universidade Federal de Minas Gerais, Departamento de Quimica (Brazil); Domingos Fabris, Jose [Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM) (Brazil); Paniago, Roberto M. [ICEx, Universidade Federal de Minas Gerais, Departamento de Fisica (Brazil); Monteiro, Douglas Santos; Pereira, Marcio Cesar, E-mail: mcpqui@gmail.com [Instituto de Ciencia, Engenharia e Tecnologia, UFVJM (Brazil)

    2013-04-15

    Experimental evidences on its in vitro use reveal that {delta}-FeOOH is a material that release-controlled amount of heat if placed under an AC magnetic field. {delta}-FeOOH nanoparticles were prepared by precipitating Fe(OH){sub 2} in alkaline solution followed by fast oxidation with H{sub 2}O{sub 2}. XRD and {sup 57}Fe Moessbauer spectroscopy data confirmed that {delta}-FeOOH is indeed the only iron-bearing compound in the produced sample. TEM images evidence that the averaged particle sizes for this {delta}-FeOOH sample is 23 nm. Magnetization measurements indicate that these {delta}-FeOOH particles behave superparamagnetically at 300 K; its saturation magnetization was found to be 13.2 emu g{sup -1}; the coercivity and the remnant magnetization were zero at 300 K. The specific absorption rate values at 225 kHz were 2.1, 6.2, and 34.2 W g{sup -1}, under 38, 64, and 112 mT, respectively. The release rate of heat can be directly controlled by changing the mass of {delta}-FeOOH nanoparticles. In view of these findings, the so-prepared {delta}-FeOOH is a real alternative to be further tested as a material for medical practices in therapies involving magnetic hyperthermia as in clinical oncology.

  7. Magnetic properties of materials for MR engineering, micro-MR and beyond.

    Science.gov (United States)

    Wapler, Matthias C; Leupold, Jochen; Dragonu, Iulius; von Elverfeld, Dominik; Zaitsev, Maxim; Wallrabe, Ulrike

    2014-05-01

    We present the results of a systematic measurement of the magnetic susceptibility of small material samples in a 9.4 T MRI scanner. We measured many of the most widely used materials in MR engineering and MR micro technology, including various polymers, optical and substrate glasses, resins, glues, photoresists, PCB substrates and some fluids. Based on our data, we identify particularly suitable materials with susceptibilities close to water. For polyurethane resins and elastomers, we also show the MR spectra, as they may be a good substitute for silicone elastomers and good casting resins. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. An efficient recyclable magnetic material for the selective removal of organic pollutants

    Directory of Open Access Journals (Sweden)

    Clément Monteil

    2016-10-01

    Full Text Available Wastewater cleaning strategies based on the adsorption of materials are being increasingly considered, but the wide variety of organic pollutants at low concentrations still makes their removal a challenge. The hybrid material proposed here consists of a zwitterionic polyethylenimine polymer coating a magnetic core. Polyethylenimine is phosphonated at different percentages by a one-step process and used to coat maghemite nanoparticles. It selectively extracts high amounts of cationic and anionic contaminants over a wide range of pH values, depending on the adjustable number of phosphonate groups introduced on the polymer. After recovering the nanoparticles with a magnet, pollutants are quantitatively released by repeated washing with low amounts of pH-adjusted water. The material can be reused many times without noticeable loss of efficiency and is designed to resist high temperatures, oxidation and harsh conditions.

  9. Synthesis and Electronic Properties of Thermoelectric and Magnetic Nanoparticle Composite Materials

    Science.gov (United States)

    Koyano, Mikio; Kito, Daichi; Sakai, Kengo; Ariga, Tomoki

    2011-05-01

    Application of a magnetic field greatly enhances the thermoelectric efficiency of bismuth-antimony (Bi-Sb) alloys. We synthesized a hybrid of Bi-Sb alloy and magnetic nanoparticles, expecting improvement of the thermoelectric performance due to the magnetic field generated by the nanoparticles. Powder x-ray diffraction and magnetic measurements of the synthesized hybrid Bi0.88Sb0.12(FeSb)0.05 sample indicated that the ferromagnetic FeSb nanoparticles, with a size of about 30 nm, were distributed in the main phase of the Bi-Sb alloy. The FeSb nanoparticles act as soft ferromagnets in the diamagnetic host Bi-Sb alloy. The electrical resistivity ρ of the host Bi0.88Sb0.12 sample decreased concomitantly with decreasing temperature, showing a shoulder at 80 K. In contrast, ρ for the hybrid sample was enhanced below 100 K because of carrier scattering by the nanoparticles. The temperature dependence of the Seebeck coefficient S was also altered by the nanoparticle addition. In contrast, the addition of magnetic nanoparticles only slightly influenced the thermal conductivity κ. These results indicate that the addition of magnetic nanoparticles to thermoelectric materials modulates the electronic structures but does not influence the lattice system.

  10. Magnetic composites based on metallic nickel and molybdenum carbide: A potential material for pollutants removal

    Energy Technology Data Exchange (ETDEWEB)

    Mambrini, Raquel V.; Fonseca, Thales L. [Departamento de Quimica, Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-901 (Brazil); Dias, Anderson [Departamento de Quimica, Universidade Federal de Ouro Preto, Ouro Preto, MG 35400-000 (Brazil); Oliveira, Luiz C.A.; Araujo, Maria Helena [Departamento de Quimica, Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-901 (Brazil); Moura, Flavia C.C., E-mail: flaviamoura@ufmg.br [Departamento de Quimica, Universidade Federal de Minas Gerais, Belo Horizonte, MG 31270-901 (Brazil)

    2012-11-30

    Highlights: Black-Right-Pointing-Pointer New magnetic molybdenum carbide composites can be prepared by CVD from ethanol. Black-Right-Pointing-Pointer Magnetic molybdenum carbide shows promising results for pollutants removal. Black-Right-Pointing-Pointer The carbide composites can be easily recovered magnetically and reused. - Abstract: New magnetic composites based on metallic nickel and molybdenum carbide, Ni/Mo{sub 2}C, have been produced via catalytic chemical vapor deposition from ethanol. Scanning electron microscopy, thermal analysis, Raman spectroscopy and X-ray diffraction studies suggest that the CVD process occurs in a single step. This process involves the reduction of NiMo oxides at different temperatures (700, 800 and 900 Degree-Sign C) with catalytic deposition of carbon from ethanol producing molybdenum carbide on Ni surface. In the absence of molybdenum the formation of Ni/C was observed. The magnetic molybdenum carbide was successfully used as pollutants removal by adsorption of sulfur and nitrogen compounds from liquid fuels and model dyes such as methylene blue and indigo carmine. The dibenzothiofene adsorption process over Ni/Mo{sub 2}C reached approximately 20 mg g{sup -1}, notably higher than other materials described in the literature and also removed almost all methylene blue dye. The great advantage of these carbide composites is that they may be easily recovered magnetically and reused.

  11. A study of influence of material properties on magnetic flux density induced in magneto rheological damper through finite element analysis

    Directory of Open Access Journals (Sweden)

    Gurubasavaraju T. M.

    2018-01-01

    Full Text Available Magnetorheological fluids are smart materials, which are responsive to the external stimulus and changes their rheological properties. The damper performance (damping force is dependent on the magnetic flux density induced at the annular gap. Magnetic flux density developed at fluid flow gap of MR damper due to external applied current is also dependent on materials properties of components of MR damper (such as piston head, outer cylinder and piston rod. The present paper discus about the influence of different materials selected for components of the MR damper on magnetic effect using magnetostatic analysis. Different materials such as magnetic and low carbon steels are considered for piston head of the MR damper and magnetic flux density induced at fluid flow gap (filled with MR fluid is computed for different DC current applied to the electromagnetic coil. Developed magnetic flux is used for calculating the damper force using analytical method for each case. The low carbon steel has higher magnetic permeability hence maximum magnetic flux could pass through the piston head, which leads to higher value of magnetic effect induction at the annular gap. From the analysis results it is observed that the magnetic steel and low carbon steel piston head provided maximum magnetic flux density. Eventually the higher damping force can be observed for same case.

  12. Magnetic Materials for the Selective Analysis of Peptide and Protein Biomarkers.

    Science.gov (United States)

    Piovesana, Susy; Capriotti, Anna Laura

    2017-01-01

    This mini-review article provides an overview on the use of magnetic materials for the analysis of protein biomarkers. In particular, the advantage provided by magnetic solid phase extraction will be discussed with selected examples, considering untargeted analysis for screening new biomarker proteins and targeted investigation on known and suggested new biomarkers. Aspects, such as enrichment efficiency over conventional techniques, ease of use, functionalization versatility and automation will be considered, together with quantification and deeper structure elucidation provided by coupling selective or specific enrichment to powerful characterization techniques, such as mass spectrometry. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  13. Microwave absorption properties of carbon nanocoils coated with highly controlled magnetic materials by atomic layer deposition.

    Science.gov (United States)

    Wang, Guizhen; Gao, Zhe; Tang, Shiwei; Chen, Chaoqiu; Duan, Feifei; Zhao, Shichao; Lin, Shiwei; Feng, Yuhong; Zhou, Lei; Qin, Yong

    2012-12-21

    In this work, atomic layer deposition is applied to coat carbon nanocoils with magnetic Fe(3)O(4) or Ni. The coatings have a uniform and highly controlled thickness. The coated nanocoils with coaxial multilayer nanostructures exhibit remarkably improved microwave absorption properties compared to the pristine carbon nanocoils. The enhanced absorption ability arises from the efficient complementarity between complex permittivity and permeability, chiral morphology, and multilayer structure of the products. This method can be extended to exploit other composite materials benefiting from its convenient control of the impedance matching and combination of dielectric-magnetic multiple loss mechanisms for microwave absorption applications.

  14. The effect of magnetic fields on the properties of sealing materials of airfield pavements

    Directory of Open Access Journals (Sweden)

    S. S. Nikulin

    2016-01-01

    Full Text Available Currently, much attention is paid to the improvement of production technology airfield pavements. This is due to the fact that the airfield pavements are exposed to the combined effect of diverse factors, such as temperature extremes, shock, and others. In recent years, production technology, new materials are widely used airfield pavements, which are produced on an industrial scale. Using them as airfield pavements can increase the battery life and improve the safety of air operations. In this study, the main problems arising from the operation of cement-concrete airfield pavements. To ensure the quality of long-term performance characteristics of the coating is necessary to pay great attention to the quality of the sealing seams airport paving material. Appeared in recent years, the work on the application of physical fields in production technology of polymeric materials have shown that the use can increase the number of indicators derived composites. In order to improve the quality of sealants can be applied magnetic fields of varying intensity. The above set of experimental studies on the treatment of sealing materials in a constant magnetic field with varying intensity has shown that this development can improve a number of performance characteristics of the sealant. Described analysis airfield sealant to frost. As a result of experiments, optimized conditions for the magnetic treatment of the sealant. Application of magnetic treatment with tensions from 6·104 to 30·104 A/m for 15 minutes helps to increase frost resistance sealants. The results confirmed the theory of polymer orientation under the action of magnetic treatment.

  15. PROCESSING OF SOFT MAGNETIC MATERIALS BY POWDER METALLURGY AND ANALYSIS OF THEIR PERFORMANCE IN ELECTRICAL MACHINES

    Directory of Open Access Journals (Sweden)

    W. H. D. Luna

    2017-12-01

    Full Text Available This article presents the use of finite elements to analyze the yield of electric machines based on the use of different soft magnetic materials for the rotor and the stator, in order to verify the performance in electric machine using powder metallurgy. Traditionally, the cores of electric machines are built from rolled steel plates, thus the cores developed in this work are obtained from an alternative process known as powder metallurgy, where powders of soft magnetic materials are compacted and sintered. The properties of interest were analyzed (magnetic, electric and mechanical properties and they were introduced into the software database. The topology of the rotor used was 400 W three-phase synchronous motor manufactured by WEG Motors. The results show the feasibility to replace the metal sheets of the electric machines by solid blocks obtained by powder metallurgy process with only 0.37% yield losses. In addition, the powder metallurgical process reduces the use of raw materials and energy consumption per kg of raw material processed.

  16. Phase-change material filled hollow magnetic nanoparticles for cancer therapy and dual modal bioimaging.

    Science.gov (United States)

    Li, Jinghua; Hu, Yan; Hou, Yanhua; Shen, Xinkun; Xu, Gaoqiang; Dai, Liangliang; Zhou, Jun; Liu, Yun; Cai, Kaiyong

    2015-05-21

    To develop carriers for anti-cancer drug delivery, this study reports a biocompatible and thermal responsive controlled drug delivery system based on hollow magnetic nanoparticles (HMNPs). The system is constructed simply by filling the hollow interiors of HMNPs with a phase-change material (PCM), namely, 1-tetradecanol, which has a melting point of 38 °C. The system achieves near "zero release" of both hydrophobic paclitaxel (PTX) and hydrophilic doxorubicin hydrochloride (DOX) and precise "on" or "off" drug delivery in vitro to efficiently induce cell apoptosis. Furthermore, the system displays both infrared thermal imaging and magnetic resonance imaging properties. More importantly, the system demonstrates great potential for thermo-chemo combination cancer therapy in vivo when an alternating magnetic field is applied.

  17. Nuclear Magnetic Resonance of Laser-Polarized Noble Gases in Molecules, Materials, and Organisms

    Science.gov (United States)

    Goodson, Boyd M.

    2002-04-01

    The sensitivity of conventional nuclear magnetic resonance (NMR) techniques is fundamentally limited by the ordinarily low spin polarization achievable in even the strongest NMR magnets. However, by transferring angular momentum from laser light to electronic and nuclear spins, optical pumping methods can increase the nuclear spin polarization of noble gases by several orders of magnitude, thereby greatly enhancing their NMR sensitivity. This review describes the principles and magnetic resonance applications of laser-polarized noble gases. The enormous sensitivity enhancement afforded by optical pumping can be exploited to permit a variety of novel NMR experiments across numerous disciplines. Many such experiments are reviewed, including the void-space imaging of organisms and materials, NMR and MRI of living tissues, probing structure and dynamics of molecules in solution and on surfaces, NMR sensitivity enhancement via polarization transfer, and low-field NMR and MRI.

  18. Dynamic magnetization models for soft ferromagnetic materials with coarse and fine domain structures

    Energy Technology Data Exchange (ETDEWEB)

    Zirka, S.E., E-mail: zirka@email.dp.ua [Department of Physics and Technology, Dnepropetrovsk National University, Gagarin 72, 49050 Dnepropetrovsk (Ukraine); Moroz, Y.I. [Department of Physics and Technology, Dnepropetrovsk National University, Gagarin 72, 49050 Dnepropetrovsk (Ukraine); Steentjes, S.; Hameyer, K. [Institute of Electrical Machines, RWTH Aachen University, Schinkelstr. 4, 52056 Aachen (Germany); Chwastek, K. [Faculty of Electrical Engineering, Czestochowa University of Technology, al. AK 17, 42-201 Czestochowa (Poland); Zurek, S. [Megger Instruments Ltd., Archcliffe Road, Dover, Kent, CT17 9EN (United Kingdom); Harrison, R.G. [Department of Electronics, Carleton University, Ottawa, Canada K1S 5B6 (Canada)

    2015-11-15

    We consider dynamic models, both numerical and analytical, that reproduce the magnetization field H(B) and the energy loss in ferromagnetic sheet materials with different domain structures. Conventional non-oriented (NO) and grain-oriented (GO) electrical steels are chosen as typical representatives of fine-domain and coarse-domain materials. The commonly-accepted loss separation procedures in these materials are critically analyzed. The use of a well-known simplified (“classical”) expression for the eddy-current loss is identified as the primary source of mistaken evaluations of excess loss in NO steel, in which the loss components can only be evaluated using the Maxwell (penetration) equation. The situation is quite different in GO steel, in which the loss separation is uncertain, but the total dynamic loss is several times higher than that explained by any version (numerical or analytical) of the classical approach. To illustrate the uncertainty of the loss separation in GO steel, we show that the magnetization field, and thus the total loss, in this material can be represented with equal accuracy using either the existing three-component approach or our proposed two-component technique, which makes no distinction between classical eddy-current and excess fields and losses. - Highlights: • Critical analysis of a ferromagnetic-material loss-separation principle. • This is to warn materials-science engineers about the inaccuracies resulting from this principle. • A transient model having a single dynamic component is proposed.

  19. Investigation of intrinsic defect magnetic properties in wurtzite ZnO materials

    Science.gov (United States)

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

    2017-10-01

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

  20. Influence of the materials magnetic state on the accurate determination of the magnetocaloric effect

    Directory of Open Access Journals (Sweden)

    Forchelet J.

    2012-06-01

    Full Text Available In this paper, we report a detailed study of the magnetocaloric effect (MCE in different first order magnetic transition (FOMT materials with different situation of the magnetic state (magnetic order. For this purpose, R-Co2, MnAs based compounds were considered in this study. The MCE is discussed in terms of Maxwell relation (MR and Clausius-Clapeyron (C-C equation. The deviation observed between both methods is discussed and analyzed. On the other hand, practically all the reported data of the MCE in the literature are associated to the applied external magnetic field and have not been corrected taking into account the demagnetization effect related to the materials shape. The obtained results demonstrate that this phenomenon can alter drastically the MCE values by cancelling out a large part of the external field, resulting in spurious values of the measured MCE. The effect of the demagnetization field on the magnetocaloric performances is also the subject of this paper.

  1. Development of a new magnetocaloric material used in a magnetic refrigeration device

    Directory of Open Access Journals (Sweden)

    Hardy V.

    2012-06-01

    Full Text Available Testing directly a magnetocaloric material in a magnetic refrigeration (MR system is the best way to judge of its applicative potentialities. In this spirit, an oxide expected to show promising magnetocaloric properties around room temperature (Pr0.65Sr0.35MnO3 was produced in large scale and shaped in order to build a regenerator. Magnetization, heat capacity, resistivity, thermal conductivity and a direct test in a MR device were carried out on this manganite. The results were compared to those observed in the reference material which is Gadolinium. The two main conclusions of these preliminary results are: (i the Pr0.65Sr0.35MnO3 actually displays not only a significant magnetocaloric effect but also a real refrigeration capability at room temperature; (ii the temperature spans reached in these first experiments are even found to well compare with those obtained with Gd.

  2. Effects of mechanical loading on the magnetic and dynamic properties of engineering materials

    Science.gov (United States)

    Scherthan, L.; Auerbach, H.; Deldar, S.; Jenni, K.; Wolny, J. A.; Herlitschke, M.; Wille, H.-C.; Mutter, A.; Meiser, J.; Umstätter, P.; Urbassek, H. M.; Beck, T.; Smaga, M.; Schünemann, V.

    2017-11-01

    The influence of strain on the magnetic and dynamic properties of ARMCO iron has been characterized by Mössbauer spectroscopy and by Nuclear Inelastic Scattering of synchrotron radiation. The Mössbauer spectra, taken in backscattering geometry, reveal that the magnetic texture in these materials is depending on the type of mechanical loading, monotonic or cyclic, respectively. The applicability of Nuclear Inelastic Scattering for the investigation of the dynamic properties of these macroscopic bulk-engineering materials is shown. The so obtained phonon density of states of a monotonically loaded specimen shows slight differences in its shape and spectral features in comparison to the initial state. An influence of dislocations is also reflected in theoretically calculated phonon density of states based on classical molecular dynamics simulations.

  3. Designed synthesis of MOF-derived magnetic nanoporous carbon materials for selective enrichment of glycans for glycomics analysis.

    Science.gov (United States)

    Sun, Nianrong; Zhang, Xiangmin; Deng, Chunhui

    2015-04-21

    In this work, magnetic nanoporous carbon (NPC) materials were synthesized by choosing a MOF as a sacrificial template and a carbon precursor. The obtained Co-ZIF-67 materials showed strong magnetic response, high surface area, a uniform size of mesopores and high carbon content. The Co-ZIF-67 materials were successfully applied to glycomics analysis by enriching N-linked glycans in bio-samples with high selectivity and efficiency.

  4. Advances in Magnetically Separable Photocatalysts: Smart, Recyclable Materials for Water Pollution Mitigation

    Directory of Open Access Journals (Sweden)

    Gcina Mamba

    2016-06-01

    Full Text Available Organic and inorganic compounds utilised at different stages of various industrial processes are lost into effluent water and eventually find their way into fresh water sources where they cause devastating effects on the ecosystem due to their stability, toxicity, and non-biodegradable nature. Semiconductor photocatalysis has been highlighted as a promising technology for the treatment of water laden with organic, inorganic, and microbial pollutants. However, these semiconductor photocatalysts are applied in powdered form, which makes separation and recycling after treatment extremely difficult. This not only leads to loss of the photocatalyst but also to secondary pollution by the photocatalyst particles. The introduction of various magnetic nanoparticles such as magnetite, maghemite, ferrites, etc. into the photocatalyst matrix has recently become an area of intense research because it allows for the easy separation of the photocatalyst from the treated water using an external magnetic field. Herein, we discuss the recent developments in terms of synthesis and photocatalytic properties of magnetically separable nanocomposites towards water treatment. The influence of the magnetic nanoparticles in the optical properties, charge transfer mechanism, and overall photocatalytic activity is deliberated based on selected results. We conclude the review by providing summary remarks on the successes of magnetic photocatalysts and present some of the future challenges regarding the exploitation of these materials in water treatment.

  5. Adjustable Permanent Quadrupoles Using Rotating Magnet Material Rods for the Next Linear Collider.

    CERN Document Server

    Spencer, C M

    2002-01-01

    The proposed Next Linear Collider (NLC) will require over 1400 adjustable quadrupoles between the main linacs' accelerator structures. These 12.7 mm bore quadrupoles will have a range of integrated strength from 0.6 to 132 Tesla, with a maximum gradient of 135 Tesla per meter, an adjustment range of +0 -20% and effective lengths from 324 mm to 972 mm. The magnetic center must remain stable to within 1 micrometer during the 20% adjustment. In an effort to reduce estimated costs and increase reliability, several designs using hybrid permanent magnets have been developed. All magnets have iron poles and use either Samarium Cobalt or Neodymium Iron to provide the magnetic fields. Two prototypes use rotating rods containing permanent magnetic material to vary the gradient. Gradient changes of 20% and center shifts of less than 20 microns have been measured. These data are compared to an equivalent electromagnet prototype. See High Reliability Prototype Quadrupole for the Next Linear Collider by C.E Rago, C.M SPENC...

  6. Tools to Study Interfaces for Superconducting, Thermoelectric, and Magnetic Materials at the University of Houston

    Science.gov (United States)

    2016-09-01

    Agilent Spectrophotometer $ 69,494.68 Dynapower DC power supply $ 36,581.00 Hummingbird Precision Machine NanoManipulation Holder for JEOL 2010F TEM...be used to study the electronic spectroscopic, defect, magnetic, and transport properties of the interfaces. - We will construct and identify the... Agilent Spectrophotometer. The ex situ electrical and electrochemical studies on the materials will be carried out with the electrochemical

  7. Magnetization of Steel Building Materials and Structures in the Natural Geomagnetic Field

    Directory of Open Access Journals (Sweden)

    E. Čermáková

    2005-01-01

    Full Text Available This paper presents the physical basis of the magnetic properties of ferromagnetic materials and shows their relationships with external geomagnetic field. It graphically processes the experimental data detected by an HMR magnetometer. Taking into account the natural geomagnetic field under the effects of steel U profiles, variations of the natural geomagnetic field in a steel structure building are indicated and the potential existence of Sick Building Syndrome (SBS in these types of buildings is pointed out. 

  8. High Frequency Inverter Power Stage Design Considerations for Non-Magnetic Materials Induction Cooking

    OpenAIRE

    Liu, Zidong

    2011-01-01

    Recently induction cookers, which are based on induction heating principle, have become quite popular due to their advantages such as high energy efficiency, safety, cleanliness, and compact size. However, it is widely known that with current technology, induction cookers require the cookware to be made of magnetic materials such as iron and stainless steel. This is why a lot of cookware is labeled â Induction Readyâ on the bottom. The limited choice of â Induction Readyâ cookware ca...

  9. Method of making active magnetic refrigerant materials based on Gd-Si-Ge alloys

    Science.gov (United States)

    Pecharsky, Alexandra O.; Gschneidner, Jr., Karl A.; Pecharsky, Vitalij K.

    2006-10-03

    An alloy made of heat treated material represented by Gd.sub.5(Si.sub.xGe.sub.1-x).sub.4 where 0.47.ltoreq.x.ltoreq.0.56 that exhibits a magnetic entropy change (-.DELTA.S.sub.m) of at least 16 J/kg K, a magnetostriction of at least 2000 parts per million, and a magnetoresistance of at least 5 percent at a temperature of about 300K and below, and method of heat treating the material between 800 to 1600 degrees C. for a time to this end.

  10. Cryogenic Properties of Inorganic Insulation Materials for ITER Magnets: A Review

    Energy Technology Data Exchange (ETDEWEB)

    Simon, N.J.

    1994-12-01

    Results of a literature search on the cryogenic properties of candidate inorganic insulators for the ITER TF magnets are reported. The materials investigated include: Al{sub 2}O{sub 3}, AlN, MgO, porcelain, SiO{sub 2}, MgAl{sub 2}O{sub 4}, ZrO{sub 2}, and mica. A graphical presentation is given of mechanical, elastic, electrical, and thermal properties between 4 and 300 K. A companion report reviews the low temperature irradiation resistance of these materials.

  11. Searching for magnetic monopoles trapped in accelerator material at the Large Hadron Collider

    CERN Document Server

    Joergensen, M.Dam; Hachler, H.-P.; Hirt, A.; Katre, A.; Mermod, P.; Milstead, D.; Sloan, T.

    2012-01-01

    If produced in high energy particle collisions at the LHC, magnetic monopoles could stop in material surrounding the interaction points. Obsolete parts of the beam pipe near the CMS interaction region, which were exposed to the products of pp and heavy ion collisions, were analysed using a SQUID-based magnetometer. The purpose of this work is to quantify the performance of the magnetometer in the context of a monopole search using a small set of samples of accelerator material ahead of the 2013 shutdown.

  12. The Science and Technology Challenges of the Plasma-Material Interface for Magnetic Fusion Energy

    Science.gov (United States)

    Whyte, Dennis

    2013-09-01

    The boundary plasma and plasma-material interactions of magnetic fusion devices are reviewed. The boundary of magnetic confinement devices, from the high-temperature, collisionless pedestal through to the surrounding surfaces and the nearby cold high-density collisional plasmas, encompasses an enormous range of plasma and material physics, and their integrated coupling. Due to fundamental limits of material response the boundary will largely define the viability of future large MFE experiments (ITER) and reactors (e.g. ARIES designs). The fusion community faces an enormous knowledge deficit in stepping from present devices, and even ITER, towards fusion devices typical of that required for efficient energy production. This deficit will be bridged by improving our fundamental science understanding of this complex interface region. The research activities and gaps are reviewed and organized to three major axes of challenges: power density, plasma duration, and material temperature. The boundary can also be considered a multi-scale system of coupled plasma and material science regulated through the non-linear interface of the sheath. Measurement, theory and modeling across these scales are reviewed, with a particular emphasis on establishing the use dimensionless parameters to understand this complex system. Proposed technology and science innovations towards solving the PMI/boundary challenges will be examined. Supported by US DOE award DE-SC00-02060 and cooperative agreement DE-FC02-99ER54512.

  13. Modeling shape effects in nano magnetic materials with Web based micromagnetics

    Science.gov (United States)

    Zhao, Zhidong

    This research work focuses on the geometry and shape effects on submicron magnetic material. A web based micromagnetics program is written to model the hysteresis loop of nano magnetic samples with arbitrary geometry shapes and multiple magnetic materials. Three material samples have been modeled with this program along with nano magnets with a variety of geometric shapes. Shape anisotropy has been introduced to a permalloy ring by adding a cross-tie structure with various widths. The in-plane hysteresis loop and reversal behavior have no notable difference in direction parallel to the cross-tie, but greatly changed in perpendicular and diagonal directions. The switching field distribution is significantly reduced. The two distinct "onion" bit states of the modified ring elements are stabilized in the hysteresis in the diagonal direction The changes in the modified rings make them better candidates for Magnetic Random Access Memory elements. Two Pac-Man elements, PM I and PM II, geometrically modified from disc and half disc respectively, are modeled. The PM I element undergoes a magnetic reversal through a two-stage mechanism that involves nucleation in the left and right middle areas followed by vortex core formation and vortex core motion in the lower middle area. The reversal process of the PM II element lacks the vortex core formation and motion stage. The switching field of the PM I and PM II elements are the same but the switching field distribution of the PM II elements is much narrower than that of the PM I element. Only the PM II element meets MRAM application requirements. The thickness dependence of the magnetic properties of a core-shell structure has been studied. The nano particles have a cobalt core and a permalloy shell. The nano spheres are the same size but with various shell thickness. Simulations reveal a multi-stage reversal process without the formation of a Bloch wall for thin shell structure and smooth reversal process with the formation

  14. Millimetre-wave magneto-optical studies of systems with reduced dimensionality

    CERN Document Server

    Rzepniewski, E J

    2001-01-01

    branches are found, which arise from the complicated nature of the band dispersion in this metal. In Chapter 5, a resonant absorption of microwaves is observed in the superconducting state of kappa-(BEDT-TTF) sub 2 Cu(NCS) sub 2 and interpreted as a Josephson Plasma Resonance. The superconducting to normal transition is studied as a function of temperature and provides information about the temperature dependence of the upper critical field in kappa-(BEDT-TTF) sub 2 Cu(NCS) sub 2. Chapter 6 presents measurements of electron paramagnetic resonance in the quasi-two dimensional Heisenberg antiferromagnet Cs sub 2 CuCl sub 4. The evolution of the magnetic resonance absorption between the high temperature region (the paramagnetic regime) and temperatures below T sub N (the antiferromagnetic regime), is studied for a range of crystal orientations. At temperatures considerably higher than T sub N , the magneto-optical data show the onset of short-range spin correlations. Experimental studies of the magneto-optical r...

  15. PA20 : A new SANS and GISANS project for soft matter, materials and magnetism

    Science.gov (United States)

    Chaboussant, Grégory; Désert, Sylvain; Lavie, Pascal; Brûlet, Annie

    2012-02-01

    This article presents the new Small Angle Neutron Scattering (SANS) instrument PA20 which will replace the PAXE instrument at LLB-Orphée. SANS is well-known to be especially well adapted to research in soft matter, materials and nanosciences and SANS is particularly powerful in the studies of complex systems, with isotopic labeling and contrast variation method, but also for large-scale structures (magnetic or not). PA20 is part of the LLB instrumental upgrade program "CAP2015". PA20 will not only maintain LLB's capabilities in SANS, but also considerably extend them in terms of SANS for magnetism with a polarized neutron option and Grazing Incidence SANS (GISANS), with an improved dynamical Q-range. The total length of PA20 will be 40 m, including a 19 m collimation length, a 20 m detector tank containing high-resolution/high-emciency XY detectors, and a casemate containing a monochromator (velocity selector λ = 0.3 - 2 nm), a chopper system for Time-of-Flight (TOF) mode, a polarizer and an RF spin flipper. PA20 will allow faster measurements, with "single-shot" access to a wider range of scattering vectors, on possibly small samples (few mm in size). In addition, polarized neutrons will enable magnetic studies in both SANS and GISANS configurations. Studies of nanostructured surfaces and interfaces (deposited or embedded nano-objects), magnetic domain formation, multilayered materials or magnetic thin films through specular and off-specular signals will be possible through GISANS setups. The versatility of PA20 should contribute to both enlarge the neutron user community, especially in expanding areas like nanosciences, and offer improved services for users in the years to come.

  16. ZFC/FC of oriented magnetic material in the Solenopsis interrupta head with antennae: characterization by FMR and SQUID.

    Science.gov (United States)

    Abraçado, Leida G; Esquivel, D M S; Wajnberg, Eliane

    2012-09-01

    Ferromagnetic resonance and SQUID magnetometry have been used to study magnetic material in the head with antennae, thorax, and abdomen of Solenopsis interrupta ants. The temperature dependence of the head with antennae using both techniques was measured. Room-temperature spectra and saturation magnetization were used to compare the magnetic material amount in the ant body parts. Both techniques show that the highest magnetic material fraction is in the head with antennae. The ordering temperature is observed at 100 ± 20 K for the ferromagnetic resonance spectra HF component. The estimated magnetic anisotropy constant K and g-values at room temperature are in good agreement with magnetite, supporting this material as the main magnetic particle constituent in the Solenopsis interrupta head with antenna. Particle diameters of 26 ± 2 nm and smaller than 14 nm were estimated. This work suggests that the head with antenna of the Solenopsis interrupta ant contains organized magnetic material and points to it as a good candidate as a magnetic sensor.

  17. Tokamak Physics EXperiment (TPX): Toroidal field magnet design, development and manufacture. SDRL 21, Materials and processes selection. Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    Smith, B.R. [Babcock and Wilcox Co., Lynchburg, VA (United States)

    1995-08-15

    This document identifies the candidate materials and manufacturing processes selected for development of the TPX Toroidal Field (TF) Magnet. Supporting rationale and selection criteria are provided for justification and the materials properties database report is included for completeness. Specific properties for each material selection are included in this document.

  18. Layered materials

    Science.gov (United States)

    Johnson, David; Clarke, Simon; Wiley, John; Koumoto, Kunihito

    2014-06-01

    Layered compounds, materials with a large anisotropy to their bonding, electrical and/or magnetic properties, have been important in the development of solid state chemistry, physics and engineering applications. Layered materials were the initial test bed where chemists developed intercalation chemistry that evolved into the field of topochemical reactions where researchers are able to perform sequential steps to arrive at kinetically stable products that cannot be directly prepared by other approaches. Physicists have used layered compounds to discover and understand novel phenomena made more apparent through reduced dimensionality. The discovery of charge and spin density waves and more recently the remarkable discovery in condensed matter physics of the two-dimensional topological insulating state were discovered in two-dimensional materials. The understanding developed in two-dimensional materials enabled subsequent extension of these and other phenomena into three-dimensional materials. Layered compounds have also been used in many technologies as engineers and scientists used their unique properties to solve challenging technical problems (low temperature ion conduction for batteries, easy shear planes for lubrication in vacuum, edge decorated catalyst sites for catalytic removal of sulfur from oil, etc). The articles that are published in this issue provide an excellent overview of the spectrum of activities that are being pursued, as well as an introduction to some of the most established achievements in the field. Clusters of papers discussing thermoelectric properties, electronic structure and transport properties, growth of single two-dimensional layers, intercalation and more extensive topochemical reactions and the interleaving of two structures to form new materials highlight the breadth of current research in this area. These papers will hopefully serve as a useful guideline for the interested reader to different important aspects in this field and

  19. Material properties and modeling characteristics for MnFeP1-xAsx materials for application in magnetic refrigeration

    DEFF Research Database (Denmark)

    Engelbrecht, Kurt; Nielsen, Kaspar Kirstein; Bahl, Christian R.H.

    2013-01-01

    Compounds of MnFeP1-xAsx have received attention recently for their use in active magnetic regenerators (AMR) because of their relatively high isothermal entropy change and adiabatic temperature change with magnetization. However, the materials also generally exhibit a significant magnetic...... and thermal hysteresis, and it is not well understood how the hysteresis will affect performance in a practical AMR device. The amount of hysteresis shown by a material can be controlled to an extent by tuning the processing conditions used during material synthesis; therefore, knowledge of the practical...... properties. Different methods of building property functions from the measured specific heat, magnetization, and adiabatic temperature change are presented. It is shown that model predictions can be highly dependent on how the properties that are used by the AMR model are calculated. © 2013 AIP Publishing...

  20. Magnetic tracing of material from a point source in a river system

    Science.gov (United States)

    Appel, Erwin; Liu, Zhao; Mülller, Christina; Frančišković-Bilinski, Stanislav; Rösler, Wolfgang; Zhang, Qi

    2017-04-01

    In fluvial environment, the mechanism of transport, distribution, and fate of contaminants, and the resulting distribution patterns are complex but only limited studied. A case in Croatia where highly magnetic coal slag was dumped into a river for more than one century (1884-1994) offers an ideal target for studying principles of how to capture the magnetic record of environmental pollution in a river system originating from a well-defined point source. Downstream transport of the coal slag can be roughly recognized by simple sampling of river sediments, but this approach is poorly significant due to the extremely variable magnetic properties caused by hydrodynamic sorting. We suggest applying variogram analyses in river traverses to obtain more reliable values of magnetic concentration, and combining these results with modeling of river bottom magnetic anomalies in order to estimate the amount of coal slag at certain positions. A major focus of this presentation is the translocation of coal slag material to the riverbanks by flooding, i.e. the possible identification of flood affected areas and the discrimination of different flood events. Surface magnetic susceptibility (MS) mapping clearly outlines the extent of flooded areas, and repeated measurements after one year reveal the reach of two recent smaller floods within this period by spatial delineation of strong positive and negative changes of MS values. To identify older flood signatures, dense grids of vertical MS profiles were analyzed at two riverbank areas in two different ways. First, by determining differences between depth horizons at the measurement points, and second, by contouring the vertical MS profiles as a function of the distance to the river (area with flat riverbank topography) and as a function of terrain elevation (area with oblique riverbank). Single flood events cannot be discriminated, but the second approach allows to approximately identify the extent of major historical floods which

  1. Hybrid Materials Based on Magnetic Layered Double Hydroxides: A Molecular Perspective.

    Science.gov (United States)

    Abellán, Gonzalo; Martí-Gastaldo, Carlos; Ribera, Antonio; Coronado, Eugenio

    2015-06-16

    Design of functional hybrids lies at the very core of synthetic chemistry as it has enabled the development of an unlimited number of solids displaying unprecedented or even improved properties built upon the association at the molecular level of quite disparate components by chemical design. Multifunctional hybrids are a particularly appealing case among hybrid organic/inorganic materials. Here, chemical knowledge is used to deploy molecular components bearing different functionalities within a single solid so that these properties can coexist or event interact leading to unprecedented phenomena. From a molecular perspective, this can be done either by controlled assembly of organic/inorganic molecular tectons into an extended architecture of hybrid nature or by intercalation of organic moieties within the empty channels or interlamellar space offered by inorganic solids with three-dimensional (MOFs, zeolites, and mesoporous hosts) or layered structures (phosphates, silicates, metal dichalcogenides, or anionic clays). This Account specifically illustrates the use of layered double hydroxides (LDHs) in the preparation of magnetic hybrids, in line with the development of soft inorganic chemistry processes (also called "Chimie Douce"), which has significantly contributed to boost the preparation hybrid materials based on solid-state hosts and subsequent development of applications. Several features sustain the importance of LDHs in this context. Their magnetism can be manipulated at a molecular level by adequate choice of constituting metals and interlayer separation for tuning the nature and extent of magnetic interactions across and between planes. They display unparalleled versatility in accommodating a broad range of anionic species in their interlamellar space that encompasses not only simple anions but chemical systems of increasing dimensionality and functionalities. Their swelling characteristics allow for their exfoliation in organic solvents with high

  2. W.E. Henry Symposium compendium: The importance of magnetism in physics and material science

    Energy Technology Data Exchange (ETDEWEB)

    Carwell, H.

    1997-09-19

    This compendium contains papers presented at the W. E. Henry Symposium, The Importance of Magnetism in Physics and Material Science. The one-day symposium was conducted to recognize the achievements of Dr. Warren Elliot Henry as educator, scientist, and inventor in a career spanning almost 70 years. Dr. Henry, who is 88 years old, attended the symposium. Nobel Laureate, Dr. Glenn Seaborg, a friend and colleague for over 40 years, attended the event and shared his personal reminiscences. Dr. Seaborg is Associate Director-At-Large at the Lawrence Berkeley National Laboratory. The Compendium begins with three papers which demonstrate the ongoing importance of magnetism in physics and material science. Other contributions cover the highlights of Dr. Henry`s career as a researcher, educator, and inventor. Colleagues and former students share insights on the impact of Dr. Henry`s research in the field of magnetism, low temperature physics, and solid state physics; his influence on students as an educator; and his character, intellect and ingenuity, and passion for learning and teaching. They share a glimpse of the environment and times that molded him as a man, and the circumstances under which he made his great achievements despite the many challenges he faced.

  3. Magnetic Nanoparticle/Block Copolymer Hybrid Materials for the Fabrication of Electromagnetic Devices

    Science.gov (United States)

    Wang, Xinyu; Mesguich, David; Watkins, James

    2012-02-01

    Significant efforts have been directed towards incorporating inorganic nanoscopic materials into well-defined, phase-separated block copolymer systems to create hybrid materials with intriguing optical, electrical or magnetic properties. Lin et al. recently reported the use of strong interactions between NPs and one segment of weakly segregated BCP systems to drive the assembly of well-ordered morphologies while confining the NPs specifically in the desired spherical, cylindrical or lamellar domains. Here we use this approach to assemble magnetic nanoparticles of high permeability into well ordered systems. Magnetic nanoparticles (MNPs) were synthesized and subsequent surface functionalization and/or ligand exchange reactions were carried out to decorate the NP surfaces with hydrogen-bonding donating groups and good particle dispersibility in polar solvents. The ligand attachment was confirmed by TGA and FTIR. The morphology evolution of BCP/MNPs composites was examined by SAXS. Such ferromagnetic structures with precise geometric control in nanoscale would enable the cost-effective fabrication of more advanced devices for AC electromagnetic applications such as miniaturized antennas with extended bandwidth, integrated microwave electronics and efficient power transformers.

  4. Magnetization and frequency dependent permeability in BSTO/hexaferrite thin films and nanostructured materials

    Science.gov (United States)

    Hajndl, R.; Poddar, P.; Srikanth, H.; Dudney, N. J.

    2003-03-01

    Ferrite-dielectric composite films are excellent systems in which the electromagnetic material properties can be tuned through changes in composition as well as microstructure. We have grown Ba_0.5Sr_0.5TiO_3/BaFe_12O_19 composite thin films of varying volumetric concentrations of ferrite and dielectric components using magnetron sputtering. Optimizing the sputtering conditions and post-deposition annealing led to high quality films without any impurity phases. Static magnetic measurements using a Physical Property Measurement System (PPMS) yielded saturation magnetization values in the range of 100 to 200 emu/cm^3. A novel double transition is observed in the hysteresis loops of the composite films and ascribed to the possibility of the magneto-dielectric coupling between the ferrite grains mixed into the dielectric medium. High energy Co ion implantation was done to achieve surface modification and dramatic reduction in grain size was observed. The magnetic properties also exhibited a strong dependence on the altered microstructure due to the Co ion implantation. We also report our studies of frequency-dependent complex permeability in these films as well as a number of nanocomposite materials. An RF fixture was designed to be able to effectively measure the permeability and loss tangents in nanopowders and spin-coated nanocomposite films of iron and iron oxides. HS acknowledges support from NSF grants ECS-0102622 and ECS-0140047

  5. Moessbauer and magnetic studies of parent material from argentine pampas soils

    Energy Technology Data Exchange (ETDEWEB)

    Bidegain, J. C. [Laboratorio de Entrenamiento Multidisciplinario para la Investigacion Tecnologica (Argentina); Bartel, A. A. [Universidad Nacional de La Pampa, Facultad de Ciencias Exactas y Naturales (Argentina); Sives, F. R.; Mercader, R. C., E-mail: mercader@fisica.unlp.edu.ar [Universidad Nacional de La Plata, Departamento de Fisica, Facultad de Ciencias Exactas (Argentina)

    2007-02-15

    In order to establish a correlation between the different types of soils using hyperfine and magnetic parameters as climatic and environmental proxies, we have studied the differentiation of soil developed around 38.5{sup o} south latitude, in the central Pampas of Argentina, by means of Moessbauer spectroscopy and environmental magnetism. The soils transect (climosequence) investigated stretches from the drier west (around 64{sup o} W) to the more humid east (at around 59{sup o} W) in the Buenos Aires Province, covering a distance of 600 km. The soils studied developed during recent Holocene geologic times in a landscape characterized by small relict plateaus, slopes and depressions, dunes and prairies. The parent material consists of eolian sandy silts overlying calcrete layers. The low mean annual precipitation in the western parts of the region gives rise to soils without B-horizons, which limits the agricultural use of land. The preliminary results show an increase of the paramagnetic Fe{sup 3+} relative concentration from west to east in the soils investigated. Magnetite is probably mainly responsible for the observed enhancement in the susceptibility values. The magnetic response of the parent material is similar to that of the loess part of the previously investigated loess-paleosol sequences of the Argentine loess plateau.

  6. One-pot synthesis of magnetic hybrid materials based on ovoid-like carboxymethyl-cellulose/cetyltrimethylammonium-bromide templates

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Martínez, Nubia E. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, 66450 Nuevo León (Mexico); Garza-Navarro, M.A., E-mail: marco.garzanr@uanl.edu.mx [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, 66450 Nuevo León (Mexico); Universidad Autónoma de Nuevo León, Centro de Innovación, Investigación y Desarrollo en Ingeniería y Tecnología, Apodaca, 66600 Nuevo León (Mexico); Lucio-Porto, Raúl [Université de Nantes, CNRS, Institut des Matériaux Jean Rouxel (IMN), 2 rue de la Houssinière, BP32229, 44322 Nantes Cedex 3 (France); and others

    2013-09-16

    A novel one-pot synthetic procedure to obtain magnetic hybrid nanostructured materials (HNM), based on magnetic spinel-metal-oxide (SMO) nanoparticles stabilized in ovoid-like carboxymethyl-cellulose (CMC)/cetyltrimethylammonium-bromide (CTAB) templates, is reported. The HNM were synthesized from the controlled hydrolysis of inorganic salts of Fe (II) and Fe (III) into aqueous dissolutions of CMC and CTAB. The synthesized HNM were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy and static magnetic measurements. The experimental evidence suggests that, due to the competition between CTAB molecules and SMO nanoparticles to occupy CMC intermolecular sites nearby to its carboxylate functional groups, the size of both, SMO nanoparticles and ovoid-like CMC/CTAB templates can be tuned, varying the CTAB:SMO weight ratio. Moreover, it was found that the magnetic response of the HNM depends on the confinement degree of the SMO nanoparticles into the CMC/CTAB template. Hence, their magnetic characteristics can be adjusted controlling the size of the template, the quantity and distribution of the SMO nanoparticles within the template and their size. - Graphical abstract: Display Omitted - Highlights: • The synthesis of magnetic hybrid materials is reported. • The hybrid materials were synthesized following a novel one-pot procedure. • The magnetic nanoparticles were stabilized in ovoid-like templates. • The size of the templates was tuned adjusting nanoparticles weight content. • The magnetic properties of hybrid materials depend on the size of the template.

  7. Emerging boom in nano magnetic particle incorporated high-Tc superconducting materials and technologies - A South African perspective

    CSIR Research Space (South Africa)

    Srinivasu, VV

    2009-01-01

    Full Text Available With a strategy to establish and embrace the emerging nano particle incorporated superconductivity technology (based on the HTS materials and nano magnetic particles) in South Africa, the author has initiated the following research activity in South...

  8. Multi-objective optimization of circular magnetic abrasive polishing of SUS304 and Cu materials

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, NhatTan; Yin, ShaoHui; Chen, FengJun; Yin, HanFeng [Hunan University, Changsha (China); Pham, VanThoan [Hanoi University, Hanoi (Viet Nam); Tran, TrongNhan [Industrial University of Ho Chi Minh City, HCM City (Viet Nam)

    2016-06-15

    In this paper, a Multi-objective particle swarm optimization algorithm (MOPSOA) is applied to optimize surface roughness of workpiece after circular magnetic abrasive polishing. The most important parameters of polishing model, namely current, gap between pole and workpiece, spindle speed and polishing time, were considered in this approach. The objective functions of the MOPSOA depend on the quality of surface roughness of polishing materials with both simultaneous surfaces (Ra1, Ra2), which are determined by means of experimental approach with the aid of circular magnetic field. Finally, the effectiveness of the approach is compared between the optimal results with the experimental data. The results show that the new proposed polishing optimization method is more feasible.

  9. Material deposition and migration processes with resonant magnetic perturbation fields at TEXTOR

    Science.gov (United States)

    Laengner, Ruth; Schmitz, O.; Brezinsek, S.; Coenen, J. W.; Eich, T.; Freisinger, M.; Kirschner, A.; Kreter, A.; Möller, S.; Laengner, M.; Philipps, V.; Pospieszczyk, A.; Reimer, H.; Samm, U.; Wienhold, P.; Textor Team

    2013-07-01

    Resonant Magnetic Perturbations (RMPs) are applied with the Dynamic Ergodic Divertor (DED) at TEXTOR to control the plasma edge transport and the plasma surface interaction. This leads to the formation of a three-dimensional (3D) topology of the scrape-off layer (SOL). To quantify the erosion/deposition balance and the material migration in this 3D boundary, spherical test limiters were exposed to plasmas with and without RMP fields applied. Methane doped with 13C as tracer element was injected through a gas inlet in the test limiter. The local gas source was monitored by spatially resolving spectroscopy and the resulting deposition patterns on the limiters were analysed with colourimetry and nuclear reaction analysis. These measurements were compared to simulations of the magnetic field topology simulations. The data provide evidence of a particle migration dominated by an ExB drift within stochastic zones of the 3D plasma boundary.

  10. Electric-field control of domain wall motion in perpendicularly magnetized materials.

    Science.gov (United States)

    Schellekens, A J; van den Brink, A; Franken, J H; Swagten, H J M; Koopmans, B

    2012-05-22

    Domain wall motion in materials exhibiting perpendicular magnetic anisotropy has been the subject of intensive research because of its large potential for future spintronic devices. Recently, it has been shown that perpendicular anisotropy of thin films can be influenced by electric fields. Voltage-controlled magnetic switching has already been realized, which is envisioned to lead to low-power logic and memory devices. Here we demonstrate a radically new application of this effect, namely control of domain wall motion by electric fields. We show that an applied voltage perpendicular to a Co or CoB wire can significantly increase or decrease domain wall velocities. Velocity modification over an order of magnitude is demonstrated (from 0.4 to 4 μm s(-1)), providing a first step towards electrical control of domain wall devices. This opens up possibilities of real-time and local control of domain wall motion by electric fields at extremely low power cost.

  11. 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.

  12. Magnetic Properties of FeNi-Based Thin Film Materials with Different Additives

    Directory of Open Access Journals (Sweden)

    Cai Liang

    2014-07-01

    Full Text Available This paper presents a study of FeNi-based thin film materials deposited with Mo, Al and B using a co-sputtering process. The existence of soft magnetic properties in combination with strong magneto-mechanical coupling makes these materials attractive for sensor applications. Our findings show that FeNi deposited with Mo or Al yields magnetically soft materials and that depositing with B further increases the softness. The out-of-plane magnetic anisotropy of FeNi thin films is reduced by depositing with Al and completely removed by depositing with B. The effect of depositing with Mo is dependent on the Mo concentration. The coercivity of FeNiMo and FeNiAl is reduced to less than a half of that of FeNi, and a value as low as 40 A/m is obtained for FeNiB. The surfaces of the obtained FeNiMo, FeNiAl and FeNiB thin films reveal very different morphologies. The surface of FeNiMo shows nano-cracks, while the FeNiAl films show large clusters and fewer nano-cracks. When FeNi is deposited with B, a very smooth morphology is obtained. The crystal structure of FeNiMo strongly depends on the depositant concentration and changes into an amorphous structure at a higher Mo level. FeNiAl thin films remain polycrystalline, even at a very high concentration of Al, and FeNiB films are amorphous, even at a very low concentration of B.

  13. Magnetic properties of FeNi-based thin film materials with different additives

    KAUST Repository

    Liang, C.

    2014-07-04

    This paper presents a study of FeNi-based thin film materials deposited with Mo, Al and B using a co-sputtering process. The existence of soft magnetic properties in combination with strong magneto-mechanical coupling makes these materials attractive for sensor applications. Our findings show that FeNi deposited with Mo or Al yields magnetically soft materials and that depositing with B further increases the softness. The out-of-plane magnetic anisotropy of FeNi thin films is reduced by depositing with Al and completely removed by depositing with B. The effect of depositing with Mo is dependent on the Mo concentration. The coercivity of FeNiMo and FeNiAl is reduced to less than a half of that of FeNi, and a value as low as 40 A/m is obtained for FeNiB. The surfaces of the obtained FeNiMo, FeNiAl and FeNiB thin films reveal very different morphologies. The surface of FeNiMo shows nano-cracks, while the FeNiAl films show large clusters and fewer nano-cracks. When FeNi is deposited with B, a very smooth morphology is obtained. The crystal structure of FeNiMo strongly depends on the depositant concentration and changes into an amorphous structure at a higher Mo level. FeNiAl thin films remain polycrystalline, even at a very high concentration of Al, and FeNiB films are amorphous, even at a very low concentration of B. 2014 by the authors.

  14. Methods for Computing Accurate Atomic Spin Moments for Collinear and Noncollinear Magnetism in Periodic and Nonperiodic Materials.

    Science.gov (United States)

    Manz, Thomas A; Sholl, David S

    2011-12-13

    The partitioning of electron spin density among atoms in a material gives atomic spin moments (ASMs), which are important for understanding magnetic properties. We compare ASMs computed using different population analysis methods and introduce a method for computing density derived electrostatic and chemical (DDEC) ASMs. Bader and DDEC ASMs can be computed for periodic and nonperiodic materials with either collinear or noncollinear magnetism, while natural population analysis (NPA) ASMs can be computed for nonperiodic materials with collinear magnetism. Our results show Bader, DDEC, and (where applicable) NPA methods give similar ASMs, but different net atomic charges. Because they are optimized to reproduce both the magnetic field and the chemical states of atoms in a material, DDEC ASMs are especially suitable for constructing interaction potentials for atomistic simulations. We describe the computation of accurate ASMs for (a) a variety of systems using collinear and noncollinear spin DFT, (b) highly correlated materials (e.g., magnetite) using DFT+U, and (c) various spin states of ozone using coupled cluster expansions. The computed ASMs are in good agreement with available experimental results for a variety of periodic and nonperiodic materials. Examples considered include the antiferromagnetic metal organic framework Cu3(BTC)2, several ozone spin states, mono- and binuclear transition metal complexes, ferri- and ferro-magnetic solids (e.g., Fe3O4, Fe3Si), and simple molecular systems. We briefly discuss the theory of exchange-correlation functionals for studying noncollinear magnetism. A method for finding the ground state of systems with highly noncollinear magnetism is introduced. We use these methods to study the spin-orbit coupling potential energy surface of the single molecule magnet Fe4C40H52N4O12, which has highly noncollinear magnetism, and find that it contains unusual features that give a new interpretation to experimental data.

  15. Synthesis of magnetic and multiferroic materials from polyvinyl alcohol-based gels

    Energy Technology Data Exchange (ETDEWEB)

    Lisnevskaya, I.V.; Bobrova, I.A.; Lupeiko, T.G.

    2016-01-01

    This review article summarizes results on the synthesis of the magnetic materials including modified nickel ferrite (Ni{sub 0.9}Co{sub 0.1}Cu{sub 0.1}Fe{sub 1.9}O{sub 4−δ}), yttrium iron garnet (Y{sub 3}Fe{sub 5}O{sub 12}), lanthanum-containing manganites (M{sub x}La{sub 1−x}MnO{sub 3} (M=Pb, Ba or Sr; x=0.3−0.35)), and multiferroics (BiFeO{sub 3} and BiFe{sub 0.5}Mn{sub 0.5}O{sub 3}) from polyvinyl alcohol-based gels. It is shown that the ammonium nitrate accelerates destruction of organic components of xerogels and thus Ni{sub 0.9}Co{sub 0.1}Cu{sub 0.1}Fe{sub 1.9}O{sub 4−δ} and BiFeO{sub 3} can be prepared at record low temperatures (100 and 250 °C, respectively) which are 200–300 °C lower compared to the process where air is used as an oxidizing agent. As for the synthesis of Y{sub 3}Fe{sub 5}O{sub 12}, M{sub x}La{sub 1−x}MnO{sub 3} and BiFe{sub 0.5}Mn{sub 0.5}O{sub 3}, the presence of NH{sub 4}NO{sub 3} favors formation of foreign phases, which ultimately complicate reaction mechanisms and lead to the higher temperature to synthesize target products. Developed methods provide nanoscale magnetic and multiferroic materials with an average particle size of ∼20–50 nm. - Highlights: • This review summarizes results on the synthesis of the magnetic materials and multiferroics. • Ammonium nitrate accelerates destruction of organic components of xerogels. • Ni{sub 0.9}Co{sub 0.1}Cu{sub 0.1}Fe{sub 1.9}O{sub 4−δ} and BiFeO{sub 3} can be prepared at record low temperatures. • Developed methods provide nanoscale magnetic and multiferroic materials.

  16. Increased accumulation of magnetic nanoparticles by magnetizable implant materials for the treatment of implant-associated complications.

    Science.gov (United States)

    Angrisani, Nina; Foth, Franziska; Kietzmann, Manfred; Schumacher, Stephan; Angrisani, Gian Luigi; Christel, Anne; Behrens, Peter; Reifenrath, Janin

    2013-10-10

    In orthopaedic surgery, accumulation of agents such as anti-infectives in the bone as target tissue is difficult. The use of magnetic nanoparticles (MNPs) as carriers principally enables their accumulation via an externally applied magnetic field. Magnetizable implants are principally able to increase the strength of an externally applied magnetic field to reach also deep-seated parts in the body. Therefore, the integration of bone-addressed therapeutics in MNPs and their accumulation at a magnetic orthopaedic implant could improve the treatment of implant related infections. In this study a martensitic steel platelet as implant placeholder was used to examine its accumulation and retention capacity of MNPs in an in vitro experimental set up considering different experimental frame conditions as magnet quantity and distance to each other, implant thickness and flow velocity. The magnetic field strength increased to approximately 112% when a martensitic stainless steel platelet was located between the magnet poles. Therewith a significantly higher amount of magnetic nanoparticles could be accumulated in the area of the platelet compared to the sole magnetic field. During flushing of the tube system mimicking the in vivo blood flow, the magnetized platelet was able to retain a higher amount of MNPs without an external magnetic field compared to the set up with no mounted platelet during flushing of the system. Generally, a higher flow velocity led to lower amounts of accumulated MNPs. A higher quantity of magnets and a lower distance between magnets led to a higher magnetic field strength. Albeit not significantly the magnetic field strength tended to increase with thicker platelets. A martensitic steel platelet significantly improved the attachment of magnetic nanoparticles in an in vitro flow system and therewith indicates the potential of magnetic implant materials in orthopaedic surgery. The use of a remanent magnetic implant material could improve the efficiency

  17. Reduced Dimensionality (4,3)D-hnCOCANH Experiment: An Efficient Backbone Assignment tool for NMR studies of Proteins

    CERN Document Server

    Kumar, Dinesh

    2013-01-01

    Sequence specific resonance assignment and secondary structure determination of proteins form the basis for variety of structural and functional proteomics studies by NMR. In this context, an efficient standalone method for rapid assignment of backbone (1H, 15N, 13Ca and 13C') resonances and secondary structure determination of proteins has been presented here. Compared to currently available strategies used for the purpose, the method employs only a single reduced dimensionality (RD) experiment -(4,3)D-hnCOCANH and exploits the linear combinations of backbone (13Ca and 13C') chemical shifts to achieve a dispersion relatively better compared to those of individual chemical shifts (see the text) for efficient and rapid data analysis. Further, the experiment leads to the spectrum with direct distinction of self (intra-residue) and sequential (inter-residue) carbon correlation peaks; these appear opposite in signs and therefore can easily be discriminated without using an additional complementary experiment. On ...

  18. Influence of frequency of the excitation magnetic field and material's electric conductivity on domain wall dynamics in ferromagnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Chávez-González, A.F. [Laboratorio de Evaluación No Destructiva Electromagnética (LENDE), ESIME-SEPI, Edif. Z-4, Instituto Politécnico Nacional, Zacatenco, México D.F., México (Mexico); Pérez-Benítez, J.A., E-mail: benitez_edl@yahoo.es [Laboratorio de Evaluación No Destructiva Electromagnética (LENDE), ESIME-SEPI, Edif. Z-4, Instituto Politécnico Nacional, Zacatenco, México D.F., México (Mexico); Espina-Hernández, J.H. [Laboratorio de Evaluación No Destructiva Electromagnética (LENDE), ESIME-SEPI, Edif. Z-4, Instituto Politécnico Nacional, Zacatenco, México D.F., México (Mexico); Grössinger, R. [Institute of Solid State Physics, Vienna University of Technology, Vienna (Austria); Hallen, J.M. [Departamento de Ingeniería Metalúrgica, ESIQIE, UPALM Edif. 7, Instituto Politécnico Nacional, Zacatenco, C.P. 07738, México D.F., México (Mexico)

    2016-03-01

    The present work analyzes the influence of electric conductivity on the Magnetic Barkhausen Noise (MBN) signal using a microscopic model which includes the influence of eddy currents. This model is also implemented to explain the dependence of MBN on the frequency of the applied magnetic field. The results presented in this work allow analyzing the influence of eddy currents on MBN signals for different values of the material's electric conductivity and for different frequencies of applied magnetic field. Additionally, the outcomes of this research can be used as a reference to differentiate the influence of eddy currents from that of second phase particles in the MBN signal, which has been reported in previous works. - Highlights: • Electromagnetic simulation of MBN with eddy currents and micro-magnetism. • Influence of applied field frequency on MBN is explained. • Influence of electric conductivity on MBN is analyzed. • Hysteresis losses in ferromagnetic materials is analyzed using the model.

  19. Magnetic materials at finite temperatures: thermodynamics and combined spin and molecular dynamics derived from first principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Eisenbach, Markus [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Perera, Meewanage Dilina N. [Univ. of Georgia, Athens, GA (United States). Center for Simulational Physics; Landau, David P [Univ. of Georgia, Athens, GA (United States). Center for Simulational Physics; Nicholson, Don M. [Univ. of North Carolina, Asheville, NC (United States). Dept. of Physics; Yin, Junqi [Univ. of Tennessee, Knoxville, TN (United States). National Inst. for Computational Sciences; Brown, Greg [Florida State Univ., Tallahassee, FL (United States). Dept. of Physics

    2015-01-01

    We present a unified approach to describe the combined behavior of the atomic and magnetic degrees of freedom in magnetic materials. Using Monte Carlo simulations directly combined with first principles the Curie temperature can be obtained ab initio in good agreement with experimental values. The large scale constrained first principles calculations have been used to construct effective potentials for both the atomic and magnetic degrees of freedom that allow the unified study of influence of phonon-magnon coupling on the thermodynamics and dynamics of magnetic systems. The MC calculations predict the specific heat of iron in near perfect agreement with experimental results from 300K to above Tc and allow the identification of the importance of the magnon-phonon interaction at the phase-transition. Further Molecular Dynamics and Spin Dynamics calculations elucidate the dynamics of this coupling and open the potential for quantitative and predictive descriptions of dynamic structure factors in magnetic materials using first principles-derived simulations.

  20. Modelling of the material flow of Nd-Fe-B magnets under high temperature deformation via finite element simulation method.

    Science.gov (United States)

    Chen, Yen-Ju; Lee, Yen-I; Chang, Wen-Cheng; Hsiao, Po-Jen; You, Jr-Shian; Wang, Chun-Chieh; Wei, Chia-Min

    2017-01-01

    Hot deformation of Nd-Fe-B magnets has been studied for more than three decades. With a good combination of forming processing parameters, the remanence and (BH)max values of Nd-Fe-B magnets could be greatly increased due to the formation of anisotropic microstructures during hot deformation. In this work, a methodology is proposed for visualizing the material flow in hot-deformed Nd-Fe-B magnets via finite element simulation. Material flow in hot-deformed Nd-Fe-B magnets could be predicted by simulation, which fitted with experimental results. By utilizing this methodology, the correlation between strain distribution and magnetic properties enhancement could be better understood.

  1. 2D-MTJs: introducing 2D materials in magnetic tunnel junctions

    Science.gov (United States)

    Piquemal-Banci, Maëlis; Galceran, Regina; Martin, Marie-Blandine; Godel, Florian; Anane, Abdelmadjid; Petroff, Frederic; Dlubak, Bruno; Seneor, Pierre

    2017-05-01

    This review focuses on the recent experimental integration of 2D materials, mostly graphene but also h-BN and dichalochogenides, such as MoS2 and WS2, in magnetic tunnel junctions. The main remarkable characteristic of 2D materials is the ability to gain high homogeneous atomic control over their thickness, as this is barely achievable with the usual 3D materials deposited through conventional physical vapour deposition (PVD) growth techniques. This could become a critical asset for spintronics with regard to the fabrication of spin valves, where ultra-thin layers with extreme control are targeted, especially for spin-polarized electron tunnelling. A complete overview of the state of the art is presented, and the different integrative pathways of 2D materials with ferromagnets are addressed, including the exfoliation of 2D flakes from crystals, the wet transfer steps of large scale layers, and direct chemical vapour deposition (CVD) growths catalysed on ferromagnetic electrodes. Interestingly, these recent experiments have already highlighted some novel properties that emanate from 2D-based heterostructures, such as passivation against oxidation diffusion and augmented spin filtering at the interface. Many perspectives are thus being opened up in the exploration of the vast amount of 2D material families and their association in heterostructures, targeting specific spin device properties.

  2. A Survey on Synthesis Processes of Structured Materials for Biomedical Applications: Iron-based Magnetic Nanoparticles, Polymeric Materials and Polymerization Processes.

    Science.gov (United States)

    Neto, Weslany Silvério; Jensen, Alan Thyago; Ferreira, Gabriella Ribeiro; Valadares, Leonardo Fonseca; Gambetta, Rossano; Gonçalves, Sílvia Belém; Machado, Fabricio

    2015-01-01

    Magnetic materials based on iron oxides are extensively designed for several biomedical applications. Heterogeneous polymerization processes are powerful tools for the production of tailored micro-sized and nanosized magneto-polymeric particles. Although several polymerization processes have been adopted along the years, suspension, emulsion and miniemulsion systems deserve special attention due to its ability to produce spherical polymer particles containing magnetic nanoparticles homogeneously dispersed into the polymer thermoplastic matrices. The main objective of this paper is to review the main methods of synthesis of iron-based magnetic nanoparticles and to illustrate how typical polymerization processes in different dispersion medium can be successfully used to produce engineered magnetic core-shell structures. It is exemplified the use of suspension, emulsion and miniemulsion polymerization processes in order to support experimental methodologies required for the production of magnetic polymer particles intended for biomedical applications such as intravascular embolization treatments, drug delivery systems and hyperthermia treatment.

  3. Ultrafast high harmonics for probing the fastest spin and charge dynamics in magnetic materials

    Science.gov (United States)

    Grychtol, Patrick

    2015-03-01

    Ultrafast light based on the high-harmonic up-conversion of femtosecond laser pulses have been successfully employed to access resonantly enhanced magnetic contrast at the Mabsorption edges of the 3d ferromagnets Fe, Co and Ni in a table-top setup. Thus, it has been possible to study element-specific dynamics in magnetic materials at femtosecond time scales in a laboratory environment, providing a wealth of opportunities for a greater fundamental understanding of correlated phenomena in solid-state matter. However, these investigations have so far been limited to linear polarized harmonics, since most techniques by which circular soft x-rays can be generated are highly inefficient reducing the photon flux to a level unfit for scientific applications. Besides presenting key findings of our ultrafast studies on charge and spin dynamics, we introduce a simple setup which allows for the efficient generation of circular harmonics bright enough for XMCD experiments. Our work thus represents a critical advance that enables element-specific imaging and spectroscopy of multiple elements simultaneously in magnetic and other chiral media with very high spatial and temporal resolution on the tabletop. In collboration with Ronny Knut, Emrah Turgut, Dmitriy Zusin, Christian Gentry, Henry Kapteyn, Margaret Murnane, JILA, University of Colorado, Boulder; Justin Shaw, Hans Nembach, Tom Silva, Electromagnetics Division, NIST, Boulder, CO; and Ofer Kfir, Avner Fleischer, Oren Cohen, Extreme Nonlinear Optics Group, Solid State Institute, Technion, Israel.

  4. Magnetic composites based on metallic nickel and molybdenum carbide: a potential material for pollutants removal.

    Science.gov (United States)

    Mambrini, Raquel V; Fonseca, Thales L; Dias, Anderson; Oliveira, Luiz C A; Araujo, Maria Helena; Moura, Flávia C C

    2012-11-30

    New magnetic composites based on metallic nickel and molybdenum carbide, Ni/Mo(2)C, have been produced via catalytic chemical vapor deposition from ethanol. Scanning electron microscopy, thermal analysis, Raman spectroscopy and X-ray diffraction studies suggest that the CVD process occurs in a single step. This process involves the reduction of NiMo oxides at different temperatures (700, 800 and 900°C) with catalytic deposition of carbon from ethanol producing molybdenum carbide on Ni surface. In the absence of molybdenum the formation of Ni/C was observed. The magnetic molybdenum carbide was successfully used as pollutants removal by adsorption of sulfur and nitrogen compounds from liquid fuels and model dyes such as methylene blue and indigo carmine. The dibenzothiofene adsorption process over Ni/Mo(2)C reached approximately 20 mg g(-1), notably higher than other materials described in the literature and also removed almost all methylene blue dye. The great advantage of these carbide composites is that they may be easily recovered magnetically and reused. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Biological cell as a soft magnetoelectric material: Elucidating the physical mechanisms underpinning the detection of magnetic fields by animals

    Science.gov (United States)

    Krichen, S.; Liu, L.; Sharma, P.

    2017-10-01

    Sharks, birds, bats, turtles, and many other animals can detect magnetic fields. Aside from using this remarkable ability to exploit the terrestrial magnetic field map to sense direction, a subset is also able to implement a version of the so-called geophysical positioning system. How do these animals detect magnetic fields? The answer to this rather deceptively simple question has proven to be quite elusive. The currently prevalent theories, while providing interesting insights, fall short of explaining several aspects of magnetoreception. For example, minute magnetic particles have been detected in magnetically sensitive animals. However, how is the detected magnetic field converted into electrical signals given any lack of experimental evidence for relevant electroreceptors? In principle, a magnetoelectric material is capable of converting magnetic signals into electricity (and vice versa). This property, however, is rare and restricted to a rather small set of exotic hard crystalline materials. Indeed, such elements have never been detected in the animals studied so far. In this work we quantitatively outline the conditions under which a biological cell may detect a magnetic field and convert it into electrical signals detectable by biological cells. Specifically, we prove the existence of an overlooked strain-mediated mechanism and show that most biological cells can act as nontrivial magnetoelectric materials provided that the magnetic permeability constant is only slightly more than that of a vacuum. The enhanced magnetic permeability is easily achieved by small amounts of magnetic particles that have been experimentally detected in magnetosensitive animals. Our proposed mechanism appears to explain most of the experimental observations related to the physical basis of magnetoreception.

  6. TDR measurements looking for complex dielectric permittivity and complex magnetic permeability in lossy materials

    Science.gov (United States)

    Persico, Raffaele

    2017-04-01

    TDR probes can be exploited for the measure of the electromagnetic characteristics of the soil, or of any penetrable material. They are commonly exploited as instruments for the measure of the propagation velocity of the electromagnetic waves in the probed medium [1], in its turn useful for the proper focusing of GPR data [2-5]. However, a more refined hardware and processing can allow to extrapolate from these probes also the discrimination between dielectric and magnetic characteristics of the material under test, which can be relevant for a better interpretation of the buried scenario or in order to infer physical-chemical characteristics of the material at hand. This requires a TDR probe that can work in frequency domain, and in particular that allows to retrieve the reflection coefficient at the air soil interface. It has been already shown [6] that in lossless cases this can be promising. In the present contribution, it will be shown at the EGU conference that it is possible to look for both the relative complex permittivity and the relative magnetic permeability of the probed material, on condition that the datum has an acceptable SNR and that some diversity of information is guaranteed, either by multifrequency data or by a TDR that can prolong its arms in the soil. References [1] F. Soldovieri, G. Prisco, R. Persico, Application of Microwave Tomography in Hydrogeophysics: some examples, Vadose Zone Journal, vol. 7, n. 1 pp. 160-170, Feb. 2008. [2] I. Catapano, L. Crocco, R. Persico, M. Pieraccini, F. Soldovieri, "Linear and Nonlinear Microwave Tomography Approaches for Subsurface Prospecting: Validation on Real Data", IEEE Trans. on Antennas and Wireless Propagation Letters, vol. 5, pp. 49-53, 2006. [3] G. Leucci, N. Masini, R. Persico, F. Soldovieri." GPR and sonic tomography for structural restoration : the case of the Cathedral of Tricarico", Journal of Geophysics and Engineering, vol. 8, pp. S76-S92, Aug. 2011. [4] S. Piscitelli, E. Rizzo, F. Cristallo

  7. Developing bulk exchange spring magnets

    Energy Technology Data Exchange (ETDEWEB)

    Mccall, Scott K.; Kuntz, Joshua D.

    2017-06-27

    A method of making a bulk exchange spring magnet by providing a magnetically soft material, providing a hard magnetic material, and producing a composite of said magnetically soft material and said hard magnetic material to make the bulk exchange spring magnet. The step of producing a composite of magnetically soft material and hard magnetic material is accomplished by electrophoretic deposition of the magnetically soft material and the hard magnetic material to make the bulk exchange spring magnet.

  8. Measurement of the magnetic material properties for ferrite-loaded cavities

    Directory of Open Access Journals (Sweden)

    Klaus Klopfer

    2015-01-01

    Full Text Available Measurements of the magnetic characteristics of the Ferroxcube 8C12m ferrite material in the parameter range where the GSI heavy-ion synchrotron SIS 18 cavity resonator is operated are presented. At first, the permeability is determined as a function of frequency and bias magnetic field strength for low radio-frequency power levels. For this purpose, both reflection and transmission measurements are carried out in a test setup with two toroids. The values for the real and imaginary part obtained from the data analysis of both approaches are fully in agreement with each other, albeit the range of application of the latter setup is limited to moderate frequencies due to parasitic resonances. An empirical analytical expression is formulated which approximates the complex permeability reasonably well in the whole investigated bias and frequency range. Moreover, the B-H curve is recorded for a reduced bias current range of the cavity. The gained material characteristics are well suited for numerical eigenmode simulations for the GSI SIS 18 cavity.

  9. Magnetic cellulose nanocrystal nanocomposites for the development of green functional materials.

    Science.gov (United States)

    Lizundia, E; Maceiras, A; Vilas, J L; Martins, P; Lanceros-Mendez, S

    2017-11-01

    A magnetic cellulosic material composed of cellulose nanocrystals (CNC) and cobalt ferrite (CoFe 2 O 4 ) nanoparticles was developed through evaporation-induced self-assembly (EISA). Nanoparticles demonstrated good dispersibility within the cellulose nanocrystal template. The addition of glucose to CNC network allows the development of homogeneous crack-free CNC-based films and does no modify neither the morphology nor the optical properties. In contrast, the introduction of CoFe 2 O 4 nanoparticles produces a marked decrease in the amount of the transmitted light. 20wt.% of CoFe 2 O 4 nanoparticles inside the CNC matrix induced a maximum magnetization value of 12.96emug -1 , increased the real part of the dielectric constant (permittivity) from 10 (pure CNC film) to 12 and improved the thermostability of the nanocomposite as evidenced by the increase of the onset temperature from 165.1 to 220.4°C. Those features obtained in a non-petroleum-based composite provide insight into the development of the next generation of functional materials from natural origin. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Characterization of magnetic materials by low-field microwave absorption techniques

    Energy Technology Data Exchange (ETDEWEB)

    Valenzuela, R. [Departamento de Materiales Metalicos y Ceramicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico (Mexico)], E-mail: monjaras@servidor.unam.mx; Alvarez, G. [Departamento de Materiales Metalicos y Ceramicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico (Mexico); Montiel, H. [Departamento de Tecnociencias, Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico (Mexico); Gutierrez, M.P. [Departamento de Quimica Inorganica y Nuclear, Facultad de Quimica, Universidad Nacional Autonoma de Mexico (Mexico); Mata-Zamora, M.E. [Departamento de Tecnociencias, Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico (Mexico); Barron, F.; Sanchez, A.Y.; Betancourt, I. [Departamento de Materiales Metalicos y Ceramicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico (Mexico); Zamorano, R. [Departamento de Ciencia de Materiales, Instituto Politecnico Nacional (Mexico)

    2008-07-15

    A low-field non-resonant microwave absorption has recently been observed in a variety of magnetically ordered materials at low DC fields (-1000 Oe {<=}H{sub DC}{<=}+1000 Oe), which is known as low-field microwave absorption (LFA). It has been shown that LFA is essentially similar to giant magnetoimpedance (GMI), and clearly different from ferromagnetic resonance (FMR). LFA strongly depends on the anisotropy field of the sample. In contrast with FMR (which can be described as the homogeneous precession of spins in the saturated state), LFA can be thought as a spin rotation process occurring during the magnetic saturation. In this work, we present a detailed study of the basic features of LFA in several types of materials: ferrites and amorphous microwires and ribbons; in particular the effects sample shape, temperature up to the Curie transition, the influence of easy axis and the effects of annealings. These examples show that once LFA is fully understood, it can become a powerful characterization tool.

  11. Estimation of quantum correlations in magnetic materials by neutron scattering data

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ben-Qiong, E-mail: losenq@caep.cn [Key Laboratory of Neutron Physics, Institute of Nuclear Physics and Chemistry, CAEP, Mianyang 621900 (China); Wu, Lian-Ao, E-mail: lianaowu@gmail.com [Department of Theoretical Physics and History of Science, The Basque Country University (EHU/UPV), PO Box 644, 48080 Bilbao (Spain); IKERBASQUE, Basque Foundation for Science, 48011 Bilbao (Spain); Zeng, Guo-Mo [College of Physics, Jilin University, Changchun 130012 (China); Song, Jian-Ming; Luo, Wei; Lei, Yang; Sun, Guang-Ai; Chen, Bo; Peng, Shu-Ming [Key Laboratory of Neutron Physics, Institute of Nuclear Physics and Chemistry, CAEP, Mianyang 621900 (China)

    2014-10-24

    We demonstrate that inelastic neutron scattering technique can be used to indirectly detect and measure the macroscopic quantum correlations quantified by both entanglement and discord in a quantum magnetic material, VODPO{sub 4}⋅1/2 D{sub 2}O. The amount of quantum correlations is obtained by analyzing the neutron scattering data of magnetic excitations in isolated V{sup 4+} spin dimers. Our quantitative analysis shows that the critical temperature of this material can reach as high as T{sub c}=82.5 K, where quantum entanglement drops to zero. Significantly, quantum discord can even survive at T{sub c}=300 K and may be used in room temperature quantum devices. Taking into account the spin–orbit (SO) coupling, we also predict theoretically that entanglement can be significantly enhanced and the critical temperature T{sub c} increases with the strength of spin–orbit coupling. - Highlights: • We predict macroscopic quantum correlations in VODPO{sub 4} ⋅ 0.5D{sub 2}O by analyzing neutron scattering experimental data. • The critical temperature of VODPO{sub 4} ⋅ 0.5D{sub 2}O can reach as high as 82.5 K, where entanglement drops to 0. • Quantum discord can even survive at room temperature. • Entanglement can be enhanced and the critical temperature increases with the strength of DM interaction.

  12. Ingested and biomineralized magnetic material in the prey Neocapritermes opacus termite: FMR characterization

    Science.gov (United States)

    de Oliveira, J. F.; Alves, O. C.; Esquivel, D. M. S.; Wajnberg, E.

    2008-03-01

    The temperature dependence of Ferromagnetic Resonance spectra, from 5 K to 280 K, was used to study the magnetic material present in Neocapritermes opacus termite, the only prey of the Pachycondyla marginata ant. The analysis of the resonant field and peak-to-peak linewidth allowed estimating the particle diameters and the effective anisotropy energy density, KEFF, as a sum of the bulk and surface contributions. It allowed to magnetically distinguish the particles of termites as collected in field from those of termites after 3 days under a cellulose diet, introduced to eliminate ingested/digested material. The data also, suggest the presence of oriented magnetite nanoparticles with diameters of 11.6 ± 0.3 nm in termites as collected in field and (14.0 ± 0.4 nm) in that under a cellulose diet. Differences between their KEFF and its components are also observed. Two transitions are revealed in the resonant field temperature dependence, one at about 50 K that was associated to surface effects and the other at about 100 K attributed to the Verwey transition.

  13. Magnetic flux distribution in a ferromagnetic material magnetized by U-shaped electromagnets of different geometric dimensions types

    Directory of Open Access Journals (Sweden)

    Povolotskaya Anna

    2018-01-01

    Full Text Available A model experiment has been carried out on studying the type of changes in the magnetic induction in a homogeneous isotropic sample that is locally magnetized with attached U-type electromagnets of different geometrical dimensions. The study was aimed at finding out magnetic flux distribution at different locations within the sample and determining the effect that the geometry of attached electromagnets has on this distribution.

  14. Non-destructive observation of electrically detected magnetic resonance in bulk material using AC bias.

    Science.gov (United States)

    Sato, Toshiyuki; Yokoyama, Hidekatsu; Ohya, Hiroaki

    2005-07-01

    DC bias is normally found in conventional measurements of electrically detected magnetic resonance (EDMR). Usually, electrodes are formed on the sample surface to make ohmic contacts for detecting changes in the electrical characteristics of the sample material. Thus, destructive procedures are required to detect the EDMR signal of bulk material with such methods. An AC bias detection technique was developed to allow the non-destructive EDMR measurement of bulk materials. An AC bridge circuit was constructed to detect the change in impedance of the sample, which when changed by ESR, an unbalanced AC voltage can be detected. By detecting this AC bias, it is possible to cancel the effects, such as Shottky barriers, that disturb the ohmic contact between the electrodes and a sample material. Further, the AC bias current penetrates the thin surface layer of a sample such as silicon oxide, which normally obstructs a DC current. This method was utilized using conductive rubber contacts for non-destructive EDMR measurements of part of a silicon wafer. EDMR spectra observed were the same as those obtained by the conventional method of using DC bias detection.

  15. Influence of standard RF coil materials on surface and buildup dose from a 6 MV photon beam in magnetic field.

    Science.gov (United States)

    Ghila, A; Fallone, B G; Rathee, S

    2016-11-01

    Magnetic resonance guided teletherapy systems aspire to image the patient concurrently with the radiation delivery. Thus, the radiofrequency (RF) coils used for magnetic resonance imaging, placed on or close to patient skin and in close proximity to the treatment volume, would be irradiated leading to modifications of radiation dose to the skin and in the buildup region. The purpose of this work is to measure and assess these dose modifications due to standard off-the-shelf RF coil materials. A typical surface coil was approximated as layered sheets of polycarbonate, copper tape, and Teflon to emulate the base, conductor, and cover, respectively. A separate investigation used additional coil materials, such as copper pipe, plastic coil housing, a typical coil padding material, and a thin copper conductor. The materials were placed in the path of a 6 MV photon beam at various distances from polystyrene phantoms in which the surface and buildup doses were measured. The experiments were performed on a clinical Varian linac with no magnetic field and with a 0.21 T electromagnet producing a magnetic field parallel to the beam central axis. The authors repeated similar experiments in the presence of a 0.22 T magnetic field oriented perpendicular to the beam central axis using an earlier linac-MR prototype, with a biplanar permanent magnet. The radiation detectors used for the measurements were two different parallel plate ion chambers and GAFChromic films. A typical open beam surface dose of 20% (relative to open beam Dmax) was increased to 63% by the coil padding material and to >74% by all other materials when placed in direct contact with the phantom, irrespective of magnetic field presence or orientation. Without a magnetic field, the surface dose decreased as the test materials were moved away from the phantom surface toward the radiation source, reaching between 30% and 40% at 10 cm gap between the phantom and the test materials. In the presence of the transverse

  16. Manufacture of electrical and magnetic graded and anisotropic materials for novel manipulations of microwaves.

    Science.gov (United States)

    Grant, P S; Castles, F; Lei, Q; Wang, Y; Janurudin, J M; Isakov, D; Speller, S; Dancer, C; Grovenor, C R M

    2015-08-28

    Spatial transformations (ST) provide a design framework to generate a required spatial distribution of electrical and magnetic properties of materials to effect manipulations of electromagnetic waves. To obtain the electromagnetic properties required by these designs, the most common materials approach has involved periodic arrays of metal-containing subwavelength elements. While aspects of ST theory have been confirmed using these structures, they are often disadvantaged by narrowband operation, high losses and difficulties in implementation. An all-dielectric approach involves weaker interactions with applied fields, but may offer more flexibility for practical implementation. This paper investigates manufacturing approaches to produce composite materials that may be conveniently arranged spatially, according to ST-based designs. A key aim is to highlight the limitations and possibilities of various manufacturing approaches, to constrain designs to those that may be achievable. The article focuses on polymer-based nano- and microcomposites in which interactions with microwaves are achieved by loading the polymers with high-permittivity and high-permeability particles, and manufacturing approaches based on spray deposition, extrusion, casting and additive manufacture.

  17. Electrical, thermal, catalytic and magnetic properties of nano-structured materials and their applications

    Science.gov (United States)

    Liu, Zuwei

    Nanotechnology is a subject that studies the fabrication, properties, and applications of materials on the nanometer-scale. Top-down and bottom-up approaches are commonly used in nano-structure fabrication. The top-down approach is used to fabricate nano-structures from bulk materials by lithography, etching, and polishing etc. It is commonly used in mechanical, electronic, and photonic devices. Bottom-up approaches fabricate nano-structures from atoms or molecules by chemical synthesis, self-assembly, and deposition, such as sol-gel processing, molecular beam epitaxy (MBE), focused ion beam (FIB) milling/deposition, chemical vapor deposition (CVD), and electro-deposition etc. Nano-structures can have several different dimensionalities, including zero-dimensional nano-structures, such as fullerenes, nano-particles, quantum dots, nano-sized clusters; one-dimensional nano-structures, such as carbon nanotubes, metallic and semiconducting nanowires; two-dimensional nano-structures, such as graphene, super lattice, thin films; and three-dimensional nano-structures, such as photonic structures, anodic aluminum oxide, and molecular sieves. These nano-structured materials exhibit unique electrical, thermal, optical, mechanical, chemical, and magnetic properties in the quantum mechanical regime. Various techniques can be used to study these properties, such as scanning probe microscopy (SPM), scanning/transmission electron microscopy (SEM/TEM), micro Raman spectroscopy, etc. These unique properties have important applications in modern technologies, such as random access memories, display, solar energy conversion, chemical sensing, and bio-medical devices. This thesis includes four main topics in the broad area of nanoscience: magnetic properties of ferro-magnetic cobalt nanowires, plasmonic properties of metallic nano-particles, photocatalytic properties of titanium dioxide nanotubes, and electro-thermal-optical properties of carbon nanotubes. These materials and their

  18. Study and Characterization of Magnetic Materials for Beam Intensity Monitors at CERN

    CERN Document Server

    AUTHOR|(CDS)2082768; Jones, Owain Rhodri

    The number of particles in the beams used at CERN is measured by a family of devices called the Beam Current Transformers (BCTs). One of such devices is the DC Current Transformer (DCCT) measuring the total number of particles in an accelerator. The DCCT is built around a magnetic core made of a soft magnetic material. Currently, the DCCT cores are purchased from one of a few industrial partners. This situation might result in some significant issues with development of the DCCTs. Firstly, the choice of the core can be made only among the already developed and manufactured cores. Secondly, the industrial partners do not normally guarantee long-term availability of their products which could manifest itself as future maintenance problems. Thirdly, the cores available on the market have not been developed with CERN's intended application in mind and, hence, might be non-optimal for the DCCTs. These three factors, among others, led to a decision to investigate a possibility of in-house core manufacturing. BCT co...

  19. Organic dyes removal using magnetic Fe3O4-nanographene platelets composite materials

    Science.gov (United States)

    Taufik, Ardiansyah; Saleh, Rosari

    2017-12-01

    In the present study, the applicability of magnetic Fe3O4-nanographene platelets (Fe3O4-NGP) composite with various concentrations of NGP was explored for the degradation of methylene blue under visible light irradiation. The magnetic, morphological, and structural characteristics of the as-prepared samples were characterized by vibrating sample magnetometry, X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, high resolution transmission electron microscope, Fourier transform infrared absorption spectroscopy, and Brunauer-Emmett-Teller (BET) surface area analysis. The experimental results showed that Fe3O4-NGP composites exhibited enhanced photocatalytic performance compared to pure Fe3O4 nanoparticles. The effect of NGP concentration (wt%) on the photocatalytic activity was also studied. It revealed that the photocatalytic performance was dependent on the concentration of NGP in the composite. The weight ratio of 5 wt% was proved to be the optimal ratio. Holes are the main active species in the degradation process due to the existence of NGP materials that act as electron acceptors and inhibit recombination of electrons and holes.

  20. A (Nd, Zr(Fe, Co11.5Ti0.5Nx compound as a permanent magnet material

    Directory of Open Access Journals (Sweden)

    S. Suzuki

    2014-11-01

    Full Text Available We studied NdFe11TiNx compounds as permanent magnet materials. The (Nd0.7,Zr0.3(Fe0.75Co0.2511.5Ti0.5N0.52 powder that contained a limited amount of the α-(Fe, Co phase shows fairly good magnetic properties, such as a saturation polarization (Js of 1.68 T and an anisotropic field (Ha of 2.88 (Law of approach to saturation – 4.0 MA/m (Intersection of magnetization curves. Both properties are comparable to those of the Nd2Fe14B phase.

  1. Micromagnetic simulation of domain wall propagation along meandering magnetic strip with spatially modulated material parameters

    Directory of Open Access Journals (Sweden)

    Z. Zhang

    2017-05-01

    Full Text Available Feasibility of two-dimensional propagation of the domain wall (DW was investigated by micromagnetic simulations. Successful bit-by-bit propagation of the DW was demonstrated in a designed meandering magnetic strip with periodic material parameter modulation, used as DW pinning sites (PSs. The DW was successively shifted along the straight part and around the corner with a spin polarized current pulses with 1 ns-width, 3 ns-interval and same amplitude. A practical current amplitude margin (30 % of mid value was achieved by analyzing the energy landscape around the meandering corner and optimizing the location of the PSs, which energy barrier height assures a thermal stability criterion (>60 kBT.

  2. Tunable electronic and magnetic properties of two‐dimensional materials and their one‐dimensional derivatives

    Science.gov (United States)

    Zhang, Zhuhua; Liu, Xiaofei; Yu, Jin; Hang, Yang; Li, Yao; Guo, Yufeng; Xu, Ying; Sun, Xu; Zhou, Jianxin

    2016-01-01

    Low‐dimensional materials exhibit many exceptional properties and functionalities which can be efficiently tuned by externally applied force or fields. Here we review the current status of research on tuning the electronic and magnetic properties of low‐dimensional carbon, boron nitride, metal‐dichalcogenides, phosphorene nanomaterials by applied engineering strain, external electric field and interaction with substrates, etc, with particular focus on the progress of computational methods and studies. We highlight the similarities and differences of the property modulation among one‐ and two‐dimensional nanomaterials. Recent breakthroughs in experimental demonstration of the tunable functionalities in typical nanostructures are also presented. Finally, prospective and challenges for applying the tunable properties into functional devices are discussed. WIREs Comput Mol Sci 2016, 6:324–350. doi: 10.1002/wcms.1251 For further resources related to this article, please visit the WIREs website. Conflict of interest: The authors have declared no conflicts of interest for this article. PMID:27818710

  3. Micromagnetic simulation of domain wall propagation along meandering magnetic strip with spatially modulated material parameters

    Science.gov (United States)

    Zhang, Z.; Tanaka, T.; Matsuyama, K.

    2017-05-01

    Feasibility of two-dimensional propagation of the domain wall (DW) was investigated by micromagnetic simulations. Successful bit-by-bit propagation of the DW was demonstrated in a designed meandering magnetic strip with periodic material parameter modulation, used as DW pinning sites (PSs). The DW was successively shifted along the straight part and around the corner with a spin polarized current pulses with 1 ns-width, 3 ns-interval and same amplitude. A practical current amplitude margin (30 % of mid value) was achieved by analyzing the energy landscape around the meandering corner and optimizing the location of the PSs, which energy barrier height assures a thermal stability criterion (>60 kBT).

  4. A coordination polymer based magnetic adsorbent material for hemoglobin isolation from human whole blood, highly selective and recoverable

    Science.gov (United States)

    Zhang, Xiaoxing; Tan, Jipeng; Xu, Xinxin; Shi, Fanian; Li, Guanglu; Yang, Yiqiao

    2017-09-01

    A composite material has been obtained successfully through the loading of nanoscale coordination polymer on magnetic Fe3O4@SiO2 core-shell particle. In this composite material, coordination polymer nanoparticles distribute uniformly on Fe3O4@SiO2 and these two components are ;tied; together firmly with chemical bonds. Adsorption experiments suggest this composite material exhibits very excellent selectivity to hemoglobin. But under the same condition, its adsorption to bovine serum albumin can almost be ignored. This selectivity can be attributed to the existence of hydrophobic interactions between coordination polymer nanoparticle and hemoglobin. For composite material, the hemoglobin adsorption process follows Langmuir model perfectly with high speed. The adsorbed hemoglobin can be eluted easily by sodium dodecyl sulfate stripping reagent with structure and biological activity of hemoglobin keeps well. The composite material was also employed to separate hemoglobin from human whole blood, which receives a very satisfactory result. Furthermore, magnetic measurement reveals ferromagnetic character of this composite material with magnetization saturation 3.56 emu g-1 and this guarantees its excellent magnetic separation performance from the treated solution.

  5. Structure and magnetic properties of SiO{sub 2}/PCL novel sol–gel organic–inorganic hybrid materials

    Energy Technology Data Exchange (ETDEWEB)

    Catauro, Michelina, E-mail: michelina.catauro@unina2.it [Department of Industrial and Information Engineering, Second University of Naples, Via Roma 29, 81031 Aversa (Italy); Bollino, Flavia [Department of Industrial and Information Engineering, Second University of Naples, Via Roma 29, 81031 Aversa (Italy); Cristina Mozzati, Maria [Department of Physics, CNISM and INSTM, University of Pavia, Via Bassi 6, 27100 Pavia (Italy); Ferrara, Chiara; Mustarelli, Piercarlo [Department of Chemistry, Section of Physical Chemistry, University of Pavia and INSTM, Via Taramelli 16, 27100 Pavia (Italy)

    2013-07-15

    Organic–inorganic nanocomposite materials have been synthesized via sol–gel. They consist of an inorganic SiO{sub 2} matrix, in which different percentages of poly(ε-caprolactone) (PCL) have been incorporated. The formation of H-bonds among the carbonyl groups of the polymer chains and Si–OH group of the inorganic matrix has been proved by means of Fourier transform infrared spectroscopy (FT-IR) analysis and has been confirmed by solid-state nuclear magnetic resonance (NMR). X-Ray diffraction (XRD) analysis highlighted the amorphous nature of the synthesized materials. Scanning electron microscope (SEM) micrograph and atomic force microscope (AFM) topography showed their homogeneous morphology and nanostructure nature. Considering the opportunity to synthesize these hybrid materials under microgravity conditions by means of magnetic levitation, superconducting quantum interference device (SQUID) magnetometry has been used to quantify their magnetic susceptibility. This measure has shown that the SiO{sub 2}/PCL hybrid materials are diamagnetic and that their diamagnetic susceptibility is independent of temperature and increases with the PCL amount. - Graphical abstract: Characterization and magnetic properties of SiO{sub 2}/PCL organic–inorganic hybrid materials synthesized via sol–gel. FT-IR, Fourier transform infrared spectroscopy; solid-state NMR: solid-state nuclear magnetic resonance; SQUID: superconducting quantum interference device. - Highlights: • Sol–gel synthesis of SiO{sub 2}/PCL amorphous class I organic–inorganic hybrid materials. • FT-IR and NMR analyses show the hydrogen bonds formation between SiO{sub 2} and PCL. • AFM and SEM analyses confirm that the SiO{sub 2}/PCL are homogenous hybrid materials. • The SQUID measures show that the simples are diamagnetic. • Diamagnetic susceptibility of SiO{sub 2}/PCL materials increases with the PCL amount.

  6. An in situ accelerator-based diagnostic for plasma-material interactions science on magnetic fusion devices

    Energy Technology Data Exchange (ETDEWEB)

    Hartwig, Zachary S.; Barnard, Harold S.; Lanza, Richard C.; Sorbom, Brandon N.; Stahle, Peter W.; Whyte, Dennis G. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge Massachusetts 02139 (United States)

    2013-12-15

    This paper presents a novel particle accelerator-based diagnostic that nondestructively measures the evolution of material surface compositions inside magnetic fusion devices. The diagnostic's purpose is to contribute to an integrated understanding of plasma-material interactions in magnetic fusion, which is severely hindered by a dearth of in situ material surface diagnosis. The diagnostic aims to remotely generate isotopic concentration maps on a plasma shot-to-shot timescale that cover a large fraction of the plasma-facing surface inside of a magnetic fusion device without the need for vacuum breaks or physical access to the material surfaces. Our instrument uses a compact (∼1 m), high-current (∼1 milliamp) radio-frequency quadrupole accelerator to inject 0.9 MeV deuterons into the Alcator C-Mod tokamak at MIT. We control the tokamak magnetic fields – in between plasma shots – to steer the deuterons to material surfaces where the deuterons cause high-Q nuclear reactions with low-Z isotopes ∼5 μm into the material. The induced neutrons and gamma rays are measured with scintillation detectors; energy spectra analysis provides quantitative reconstruction of surface compositions. An overview of the diagnostic technique, known as accelerator-based in situ materials surveillance (AIMS), and the first AIMS diagnostic on the Alcator C-Mod tokamak is given. Experimental validation is shown to demonstrate that an optimized deuteron beam is injected into the tokamak, that low-Z isotopes such as deuterium and boron can be quantified on the material surfaces, and that magnetic steering provides access to different measurement locations. The first AIMS analysis, which measures the relative change in deuterium at a single surface location at the end of the Alcator C-Mod FY2012 plasma campaign, is also presented.

  7. An in situ accelerator-based diagnostic for plasma-material interactions science on magnetic fusion devices.

    Science.gov (United States)

    Hartwig, Zachary S; Barnard, Harold S; Lanza, Richard C; Sorbom, Brandon N; Stahle, Peter W; Whyte, Dennis G

    2013-12-01

    This paper presents a novel particle accelerator-based diagnostic that nondestructively measures the evolution of material surface compositions inside magnetic fusion devices. The diagnostic's purpose is to contribute to an integrated understanding of plasma-material interactions in magnetic fusion, which is severely hindered by a dearth of in situ material surface diagnosis. The diagnostic aims to remotely generate isotopic concentration maps on a plasma shot-to-shot timescale that cover a large fraction of the plasma-facing surface inside of a magnetic fusion device without the need for vacuum breaks or physical access to the material surfaces. Our instrument uses a compact (~1 m), high-current (~1 milliamp) radio-frequency quadrupole accelerator to inject 0.9 MeV deuterons into the Alcator C-Mod tokamak at MIT. We control the tokamak magnetic fields--in between plasma shots--to steer the deuterons to material surfaces where the deuterons cause high-Q nuclear reactions with low-Z isotopes ~5 μm into the material. The induced neutrons and gamma rays are measured with scintillation detectors; energy spectra analysis provides quantitative reconstruction of surface compositions. An overview of the diagnostic technique, known as accelerator-based in situ materials surveillance (AIMS), and the first AIMS diagnostic on the Alcator C-Mod tokamak is given. Experimental validation is shown to demonstrate that an optimized deuteron beam is injected into the tokamak, that low-Z isotopes such as deuterium and boron can be quantified on the material surfaces, and that magnetic steering provides access to different measurement locations. The first AIMS analysis, which measures the relative change in deuterium at a single surface location at the end of the Alcator C-Mod FY2012 plasma campaign, is also presented.

  8. Fabrication, characterization and comparison of composite magnetic materials for high efficiency integrated voltage regulators with embedded magnetic core micro-inductors

    Science.gov (United States)

    Bellaredj, Mohamed L. F.; Mueller, Sebastian; Davis, Anto K.; Mano, Yasuhiko; Kohl, Paul A.; Swaminathan, Madhavan

    2017-11-01

    High-efficiency integrated voltage regulators (IVRs) require the integration of power inductors, which have low loss and reduced size at very high frequency. The use of a magnetic material core can reduce significantly the inductor area and simultaneously increase the inductance. This paper focuses on the fabrication, characterization and modeling of nickel zinc (NiZn) ferrite and carbonyl iron powder (CIP)-epoxy magnetic composite materials, which are used as the magnetic core materials of embedded inductors in a printed wiring board (PWB) for a system in package (SIP) based buck type IVR. The fabricated composite materials and process are fully compatible with FR4 epoxy resin prepreg and laminate. For 85% weight loading of the magnetic powder (around 100 MHz at room temperature), the composite materials show a relative permeability of 7.5-8.1 for the NiZn ferrite composite and 5.2-5.6 for the CIP composite and a loss tangent value of 0.24-0.28 for the NiZn ferrite composite and 0.09-0.1 for the CIP-composite. The room temperature saturation flux density values are 0.1351 T and 0.5280 T for the NiZn ferrite and the CIP composites, respectively. The frequency dispersion parameters of the magnetic composites are modeled using a simplified Lorentz and Landau-Lifshitz-Gilbert equation for a Debye type relaxation. Embedded magnetic core solenoid inductors were designed based on the composite materials for the output filter of a high-efficiency SIP based buck type IVR. Evaluation of a SIP based buck type IVR with the designed inductors shows that it can reach peak efficiencies of 91.7% at 11 MHz for the NiZn ferrite-composite, 91.6% at 14 MHz for CIP-composite and 87.5% (NiZn ferrite-composite) and 87.3% (CIP-composite) efficiency at 100 MHz for a 1.7 V:1.05 V conversion. For a direct 5 V:1 V conversion using a stacked topology, a peak efficiency of 82% at 10 MHz and 72% efficiency at 100 MHz can be achieved for both materials.

  9. Advanced electron microscopy of novel ferromagnetic materials and ferromagnet/oxide interfaces in magnetic tunnel junctions

    Science.gov (United States)

    Shi, Fengyuan

    We have studied novel ferromagnetic (FM) materials and FM electrode/tunnel barrier interfaces in magnetic tunnel junctions (MTJs) by advanced electron microscopy including scanning transmission electron microscopy (HRSTEM) and electron energy loss spectroscopy (EELS). MTJs are one of the prototypical spintronic devices, with applications in magnetic random access memory, sensors and read heads. The performance of MTJs depends on several factors, including the FM electrodes and the FM/tunnel barrier interfaces. Therefore, to realize the high performance of MTJs, we first need high quality ferromagnetic electrodes with high spin polarization. High-quality Fe3O4 and Fe4N electrodes with theoretically predicted -100% spin polarization were fabricated by various methods and investigated by HRSTEM and STEM EELS. The Fe3O4 and Fe4N thin films have low defect density and good crystallinity, but when integrated as electrodes in a MTJ, problems emerged. In a Fe4N/AlOx/Fe MTJ, the magnetoresistance was negative, but relatively small, due to a defective Fe 3O4 reaction layer formed at the Fe4N/tunnel barrier interface revealed by HRSTEM and EELS. The interfacial reaction layer was thin and discontinuous which made direct imaging difficult. Therefore, STEM EELS was used to map out the reaction layer. A Fe3O4 reaction layer was also found in a nominally symmetric CoFe/AlOx/CoFe MTJs after annealing, which also exhibited inverse TMR and a non-symmetric bias dependence. We also investigated the MTJs with the Heusler alloy Co2MnSi as one or both electrode and crystalline MgO as the tunnel barrier, which exhibit quite high TMR due to coherent tunneling. We showed that the Co2MnSi/MgO interface in these junctions is dominated by a configuration of a pure Mn plane bonded across the interface to O. This was the first observation of that interface termination. HRSTEM images also show that the fraction of MnMn/O interface termination increases with increasing Mn concentration in the CMS

  10. Rare-Earth-Free Permanent Magnets for Electrical Vehicle Motors and Wind Turbine Generators: Hexagonal Symmetry Based Materials Systems Mn-Bi and M-type Hexaferrite

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Yang-Ki [University of Alabama; Haskew, Timothy [University of Alabama; Myryasov, Oleg [University of Alabama; Jin, Sungho [University of California San Diego; Berkowitz, Ami [University of California San Diego

    2014-06-05

    The research we conducted focuses on the rare-earth (RE)-free permanent magnet by modeling, simulating, and synthesizing exchange coupled two-phase (hard/soft) RE-free core-shell nano-structured magnet. The RE-free magnets are made of magnetically hard core materials (high anisotropy materials including Mn-Bi-X and M-type hexaferrite) coated by soft shell materials (high magnetization materials including Fe-Co or Co). Therefore, our research helps understand the exchange coupling conditions of the core/shell magnets, interface exchange behavior between core and shell materials, formation mechanism of core/shell structures, stability conditions of core and shell materials, etc.

  11. Integrating non-planar metamaterials with magnetic absorbing materials to yield ultra-broadband microwave hybrid absorbers

    Science.gov (United States)

    Li, Wei; Wu, Tianlong; Wang, Wei; Guan, Jianguo; Zhai, Pengcheng

    2014-01-01

    Broadening the bandwidth of electromagnetic wave absorbers has greatly challenged material scientists. Here, we propose a two-layer hybrid absorber consisting of a non-planar metamaterial (MM) and a magnetic microwave absorbing material (MAM). The non-planar MM using magnetic MAMs instead of dielectric substrates shows good low frequency absorption and low reflection across a broad spectrum. Benefiting from this and the high frequency strong absorption of the MAM layer, the lightweight hybrid absorber exhibits 90% absorptivity over the whole 2-18 GHz range. Our result reveals a promising and flexible method to greatly extend or control the absorption bandwidth of absorbers.

  12. Calculation of equivalent magnetic permeability of ferromagnetic materials for modeling of three-dimensional eddy current fields

    Directory of Open Access Journals (Sweden)

    Karpushkin Sergey

    2017-01-01

    Full Text Available The paper presents a method of calculating a constant value of magnetic permeability of ferromagnetic materials, equivalent to the basic magnetization curve by the criterion of real power. The proposed method makes it possible to use linear differential equations of the electromagnetic field in the analysis of three-dimensional fields of eddy currents in ferromagnetic materials, thus significantly reducing the calculation time. We propose a method of calculating the power of inductors using two-dimensional axisymmetric models. The scope of the proposed methods is limited to the case of placement of the inductor inside the ferromagnetic body.

  13. The materials physics companion

    CERN Document Server

    Fischer-Cripps, Anthony C

    2014-01-01

    Introduction to Materials Physics: Structure of matter. Solid state physics. Dynamic properties of solids. Dielectric Properties of Materials: Dielectric properties. Ferroelectric and piezoelectric materials. Dielectric breakdown. Applications of dielectrics. Magnetic Properties of Materials: Magnetic properties. Magnetic moment. Spontaneous magnetization. Superconductivity.

  14. Magnetic Processing – A Pervasive Energy Efficient Technology for Next Generation Materials for Aerospace and Specialty Steel Markets

    Energy Technology Data Exchange (ETDEWEB)

    Mackiewicz-Ludtka, G.; Ludtka, G.M.; Ray, P. (Carpenter Technologies, Inc.); Magee, J. (Carpenter Technologies, Inc.)

    2010-09-10

    Thermomagnetic Magnetic Processing is an exceptionally fertile, pervasive and cross-cutting technology that is just now being recognized by several major industry leaders for its significant potential to increase energy efficiency and materials performance for a myriad of energy intensive industries in a variety of areas and applications. ORNL has pioneered the use and development of large magnetic fields in thermomagnetically processing (T-MP) materials for altering materials phase equilibria and transformation kinetics. ORNL has discovered that using magnetic fields, we can produce unique materials responses. T-MP can produce unique phase stabilities & microstructures with improved materials performance for structural and functional applications not achieved with traditional processing techniques. These results suggest that there are unprecedented opportunities to produce significantly enhanced materials properties via atomistic level (nano-) microstructural control and manipulation. ORNL (in addition to others) have shown that grain boundary chemistry and precipitation kinetics are also affected by large magnetic fields. This CRADA has taken advantage of ORNL’s unique, custom-designed thermo-magnetic, 9 Tesla superconducting magnet facility that enables rapid heating and cooling of metallic components within the magnet bore; as well as ORNL’s expertise in high magnetic field (HMF) research. Carpenter Technologies, Corp., is a a US-based industrial company, that provides enhanced performance alloys for the Aerospace and Specialty Steel products. In this CRADA, Carpenter Technologies, Corp., is focusing on applying ORNL’s Thermomagnetic Magnetic Processing (TMP) technology to improve their current and future proprietary materials’ product performance and open up new markets for their Aerospace and Specialty Steel products. Unprecedented mechanical property performance improvements have been demonstrated for a high strength bainitic alloy industrial

  15. Correlation between charge transfer and exchange coupling in carbon-based magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Anh Tuan, E-mail: tuanna@hus.edu.vn [Faculty of Physics, VNU University of Science, 334 Nguyen Trai, Thanh Xuan, Ha Noi (Viet Nam); Science and Technology Department, Vietnam National University, Hanoi, 144 Xuan Thuy, Cau Giay, Hanoi (Viet Nam); Japan Advanced Institute of Science and Technology, 1-1, Asahidai, Nomi, Ishikawa, 923-1292 Japan (Japan); Nguyen, Van Thanh; Nguyen, Huy Sinh [Faculty of Physics, VNU University of Science, 334 Nguyen Trai, Thanh Xuan, Ha Noi (Viet Nam); Pham, Thi Tuan Anh [Faculty of Physics, VNU University of Science, 334 Nguyen Trai, Thanh Xuan, Ha Noi (Viet Nam); Faculty of Science, College of Hai Duong, Nguyen Thi Due, Hai Duong (Viet Nam); Do, Viet Thang [Faculty of Physics, VNU University of Science, 334 Nguyen Trai, Thanh Xuan, Ha Noi (Viet Nam); Faculty of Science, Haiphong University, 171 Phan Dang Luu, Kien An, Hai Phong (Viet Nam); Dam, Hieu Chi [Japan Advanced Institute of Science and Technology, 1-1, Asahidai, Nomi, Ishikawa, 923-1292 Japan (Japan)

    2015-10-15

    Several forms of carbon-based magnetic materials, i.e. single radicals, radical dimers, and alternating stacks of radicals and diamagnetic molecules, have been investigated using density-functional theory with dispersion correction and full geometry optimization. Our calculated results demonstrate that the C{sub 31}H{sub 15} (R{sub 4}) radical has a spin of ½. However, in its [R{sub 4}]{sub 2} dimer structure, the net spin becomes zero due to antiferromagnetic spin-exchange between radicals. To avoid antiferromagnetic spin-exchange of identical face-to-face radicals, eight alternating stacks, R{sub 4}/D{sub 2m}/R{sub 4} (with m = 3-10), were designed. Our calculated results show that charge transfer (Δn) between R{sub 4} radicals and the diamagnetic molecule D{sub 2m} occurs with a mechanism of spin exchange (J) in stacks. The more electrons that transfer from R{sub 4} to D{sub 2m}, the stronger the ferromagnetic spin-exchange in stacks. In addition, our calculated results show that Δn can be tailored by adjusting the electron affinity (E{sub a}) of D{sub 2m}. The correlation between Δn, E{sub a}, m, and J is discussed. These results give some hints for the design of new ferromagnetic carbon-based materials.

  16. Correlation between charge transfer and exchange coupling in carbon-based magnetic materials

    Directory of Open Access Journals (Sweden)

    Anh Tuan Nguyen

    2015-10-01

    Full Text Available Several forms of carbon-based magnetic materials, i.e. single radicals, radical dimers, and alternating stacks of radicals and diamagnetic molecules, have been investigated using density-functional theory with dispersion correction and full geometry optimization. Our calculated results demonstrate that the C31H15 (R4 radical has a spin of ½. However, in its [R4]2 dimer structure, the net spin becomes zero due to antiferromagnetic spin-exchange between radicals. To avoid antiferromagnetic spin-exchange of identical face-to-face radicals, eight alternating stacks, R4/D2m/R4 (with m = 3-10, were designed. Our calculated results show that charge transfer (Δn between R4 radicals and the diamagnetic molecule D2m occurs with a mechanism of spin exchange (J in stacks. The more electrons that transfer from R4 to D2m, the stronger the ferromagnetic spin-exchange in stacks. In addition, our calculated results show that Δn can be tailored by adjusting the electron affinity (Ea of D2m. The correlation between Δn, Ea, m, and J is discussed. These results give some hints for the design of new ferromagnetic carbon-based materials.

  17. Final Report: Stability and Novel Properties of Magnetic Materials and Ferromagnet / Insulator Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Voyles, Paul M. [Univ. of Wisconsin, Madison, WI (United States); Chang, Y. Austin [Univ. of Wisconsin, Madison, WI (United States)

    2013-07-24

    We report investigations of the synthesis, structure, and properties of new materials for spintronic applications integrated onto silicon substrates. Our primary focus is materials with very high, negative, intrinsic spin polarization of the density of states at the Fermi level. We have developed a new synthesis method for Fe3O4 thin films through selective oxidation of Fe, resulting in smooth, low-defect density films. We have synthesized Fe4N films and shown that they preferentially oxidize to Fe3O4. When integrated into magnetic tunnel junctions consisting of Fe4N / AlOx / Fe, oxidation at the Fe4N / AlOx interface creates Fe3O4, leading to negative tunneling magnetoresistance (TMR). Oxidation of Fe in nominally symmetric CoFe / AlOx / CoFe also produces Fe3O4 and negative TMR under selected oxidation conditions.

  18. NH4FeCl2(HCOO): synthesis, structure, and magnetism of a novel low-dimensional magnetic material.

    Science.gov (United States)

    Greenfield, Joshua T; Kamali, Saeed; Izquierdo, Nezhueyotl; Chen, Michael; Kovnir, Kirill

    2014-03-17

    Solvothermal synthesis was used to create a low-dimensional iron(II) chloride formate compound, NH4FeCl2(HCOO), that exhibits interesting magnetic properties. NH4FeCl2(HCOO) crystallizes in the monoclinic space group C2/c (No. 15) with a = 7.888(1) Å, b = 11.156(2) Å, c = 6.920(2) Å, and β = 108.066(2)°. The crystal structure consists of infinite zigzag chains of distorted Fe(2+)-centered octahedra linked by μ2-Cl and syn-syn formate bridges, with interchain hydrogen bonding through NH4(+) cations holding the chains together. The unique Fe(2+) site is coordinated by four equatorial chlorides at a distance of 2.50 Å and two axial oxygens at a distance of 2.08 Å. Magnetic measurements performed on powder and oriented single-crystal samples show complex anisotropic magnetic behavior dominated by antiferromagnetic interactions (TN = 6 K) with a small ferromagnetic component in the direction of chain propagation. An anisotropic metamagnetic transition was observed in the ordered state at 2 K in an applied magnetic field of 0.85-3 T. (57)Fe Mössbauer spectroscopy reveals mixed hyperfine interactions below the ordering temperature, with strong electric field gradients and complex noncollinear arrangement of the magnetic moments.

  19. Sensor Applications of Soft Magnetic Materials Based on Magneto-Impedance, Magneto-Elastic Resonance and Magneto-Electricity

    Science.gov (United States)

    García-Arribas, Alfredo; Gutiérrez, Jon; Kurlyandskaya, Galina V.; Barandiarán, José M.; Svalov, Andrey; Fernández, Eduardo; Lasheras, Andoni; de Cos, David; Bravo-Imaz, Iñaki

    2014-01-01

    The outstanding properties of selected soft magnetic materials make them successful candidates for building high performance sensors. In this paper we present our recent work regarding different sensing technologies based on the coupling of the magnetic properties of soft magnetic materials with their electric or elastic properties. In first place we report the influence on the magneto-impedance response of the thickness of Permalloy films in multilayer-sandwiched structures. An impedance change of 270% was found in the best conditions upon the application of magnetic field, with a low field sensitivity of 140%/Oe. Second, the magneto-elastic resonance of amorphous ribbons is used to demonstrate the possibility of sensitively measuring the viscosity of fluids, aimed to develop an on-line and real-time sensor capable of assessing the state of degradation of lubricant oils in machinery. A novel analysis method is shown to sensitively reveal the changes of the damping parameter of the magnetoelastic oscillations at the resonance as a function of the oil viscosity. Finally, the properties and performance of magneto-electric laminated composites of amorphous magnetic ribbons and piezoelectric polymer films are investigated, demonstrating magnetic field detection capabilities below 2.7 nT. PMID:24776934

  20. A REFINED MATHEMATICAL MODEL OF MULTIPHYSICS PROCESSES FOR MAGNETIC PULSE TREATMENT OF MATERIALS

    Directory of Open Access Journals (Sweden)

    E.I. Baida

    2015-04-01

    Full Text Available Introduction. The complexity of the theoretical description of the magnetic pulse treatment of the material is in the mutual coupled processes of electromagnetic and thermal fields with plastic deformation of the material and processes in an electrical circuit. The paper deals with the combined transient mathematical model of the system of equations of the electromagnetic field, theory of elasticity, thermal conductivity and electrical circuit. Purpose. Research and testing of the developed mathematical model and assess the impact of various parameters on the process of deformation of the work piece. Methodology. Investigation of nonlinear mathematical model is carried out by the finite element method using a special software package. Results. The resulting solution of the transient mathematical model allows studying the influence of parameters of the circuit, the speed and the characteristics of the material to plastic deformation and heating of the work piece, which allows to select the optimum process parameters. Originality. This is an integrated approach to the development of a mathematical model, which includes the electromagnetic field equations, the theory of elasticity, thermal conductivity and electrical circuit equations with a storage capacitor. Conclusions. A comprehensive mathematical model and its solution are obtained. It is established a small effect of heating temperature on the amount of strain. Currents caused by movement of the work piece must be taken into account in the calculations. Inertial forces significantly affect the nature of the deformation. During the deformation it is necessary to consider the nonlinearity of elasticity modulus. Thermal deformation of the work piece is much less mechanical strain and opposite in sign to them, but the surface temperature stresses due to the high temperature gradient equal to 20 % of the yield strength of the work piece.

  1. MAGNET

    CERN Multimedia

    by B. Curé

    2011-01-01

    The magnet operation was very satisfactory till the technical stop at the end of the year 2010. The field was ramped down on 5th December 2010, following the successful regeneration test of the turbine filters at full field on 3rd December 2010. This will limit in the future the quantity of magnet cycles, as it is no longer necessary to ramp down the magnet for this type of intervention. This is made possible by the use of the spare liquid Helium volume to cool the magnet while turbines 1 and 2 are stopped, leaving only the third turbine in operation. This obviously requires full availability of the operators to supervise the operation, as it is not automated. The cryogenics was stopped on 6th December 2010 and the magnet was left without cooling until 18th January 2011, when the cryoplant operation resumed. The magnet temperature reached 93 K. The maintenance of the vacuum pumping was done immediately after the magnet stop, when the magnet was still at very low temperature. Only the vacuum pumping of the ma...

  2. Impact of the Static and Radiofrequency Magnetic Fields Produced by a 7T MR Imager on Metallic Dental Materials.

    Science.gov (United States)

    Oriso, Kenta; Kobayashi, Takuya; Sasaki, Makoto; Uwano, Ikuko; Kihara, Hidemichi; Kondo, Hisatomo

    2016-01-01

    We examined safety issues related to the presence of various metallic dental materials in magnetic resonance (MR) imaging at 7 tesla. A 7T MR imaging scanner was used to examine 18 kinds of materials, including 8 metals used in dental restorations, 6 osseointegrated dental implants, 2 abutments for dental implants, and 2 magnetic attachment keepers. We assessed translational attraction forces between the static magnetic field and materials via deflection angles read on a tailor-made instrument and compared with those at 3T. Heating effects from radiofrequency during image acquisitions using 6 different sequences were examined by measuring associated temperature changes in agarose-gel phantoms with a fiber-optic thermometer. Deflection angles of the metallic dental materials were significantly larger at 7T than 3T. Among full metal crowns (FMCs), deflection angles were 18.0° for cobalt-chromium (Co-Cr) alloys, 13.5° for nickel-chromium (Ni-Cr) alloys, and 0° for other materials. Deflection angles of the dental implants and abutments were minimal, ranging from 5.0 to 6.5°, whereas the magnetic attachment keepers were strongly attracted to the field, having deflection angles of 90° or more. Increases in temperature of the FMCs were significant but less than 1°C in every sequence. The dental implant of 50-mm length showed significant but mild temperature increases (up to 1.5°C) when compared with other dental implants and abutments, particularly on sequences with high specific absorption rate values. Although most metallic dental materials showed no apparent translational attraction or heating at 7T, substantial attraction forces on the magnetic attachment keepers suggested potential risks to patients and research participants undergoing MR imaging examinations.

  3. Crystalline structure and magnetic properties of Fe2CrSi Heusler alloy films: New ferromagnetic material for high-performance magnetic random access memory

    Science.gov (United States)

    Yoshimura, S.; Asano, H.; Nakamura, Y.; Yamaji, K.; Takeda, Y.; Matsui, M.; Ishida, S.; Nozaki, Y.; Matsuyama, K.

    2008-04-01

    A new Heusler alloy, Fe2CrSi, which has high spin polarization (P), low saturation magnetization (Ms), and a low Curie temperature (TC), was investigated in order to fabricate high-performance magnetic tunnel junctions (MTJs) with a high tunnel magnetoresistance ratio and with low critical current for the spin-transfer switching method, or a low switching field for the thermally assisted magnetization reversal technique. The main results are as follows: (1) P and the magnetic moment of Fe2CrSi with an L21 structure were 0.98 and 1.98μB/f.u., respectively, according to density of states calculations. (2) Fe2CrSi films show the (100) orientation with a B2 structure on a MgO substrate upon a thermal treatment with optimum temperature and duration. (3) Fe2CrSi films have Ms and TC values of 385emu /cm3 and 630K, respectively. (4) The (100) oriented epitaxial MTJs are produced with Fe2CrSi films fabricated with the optimized thermal treatment condition. It is found that the Fe2CrSi Heusler alloy films are a suitable ferromagnetic material for high-performance magnetic random access memory.

  4. Testing of the permanent magnet material Mn-Al-C for potential use in propulsion motors for electric vehicles

    Science.gov (United States)

    Abdelnour, Z.; Mildrun, H.; Strant, K.

    1981-01-01

    The development of Mn-Al-C permanent magnets is reviewed. The general properties of the material are discussed and put into perspective relative to alnicos and ferrites. The traction motor designer's demands of a permanent magnet for potential use in electric vehicle drives are reviewed. Tests determined magnetic design data and mechanical strength properties. Easy axis hysteresis and demagnetization curves, recoil loops and other minor loop fields were measured over a temperature range from -50 to 150 C. Hysteresis loops were also measured for three orthogonal directions (the one easy and two hard axes of magnetization). Extruded rods of three different diameters were tested. The nonuniformity of properties over the cross section of the 31 mm diameter rod was studied. Mechanical compressive and bending strength at room temperature was determined on individual samples from the 31 mm rod.

  5. Material flow analysis of NdFeB magnets for Denmark: a comprehensive waste flow sampling and analysis approach.

    Science.gov (United States)

    Habib, Komal; Schibye, Peter Klausen; Vestbø, Andreas Peter; Dall, Ole; Wenzel, Henrik

    2014-10-21

    Neodymium-iron-boron (NdFeB) magnets have become highly desirable for modern hi-tech applications. These magnets, in general, contain two key rare earth elements (REEs), i.e., neodymium (Nd) and dysprosium (Dy), which are responsible for the very high strength of these magnets, allowing for considerable size and weight reduction in modern applications. This study aims to explore the current and future potential of a secondary supply of neodymium and dysprosium from recycling of NdFeB magnets. For this purpose, material flow analysis (MFA) has been carried out to perform the detailed mapping of stocks and flows of NdFeB magnets in Denmark. A novel element of this study is the value added to the traditionally practiced MFAs at national and/or global levels by complementing them with a comprehensive sampling and elemental analysis of NdFeB magnets, taken out from a sample of 157 different products representing 18 various product types. The results show that the current amount of neodymium and dysprosium in NdFeB magnets present in the Danish waste stream is only 3 and 0.2 Mg, respectively. However, this number is estimated to increase to 175 Mg of neodymium and 11.4 Mg of dysprosium by 2035. Nevertheless, efficient recovery of these elements from a very diverse electronic waste stream remains a logistic and economic challenge.

  6. Formation, Crystallization Behavior, and Soft Magnetic Properties of FeCSiBP Bulk Metallic Glass Fabricated Using Industrial Raw Materials

    Science.gov (United States)

    Li, H. X.; Gao, J. E.; Wang, S. L.; Yi, S.; Lu, Z. P.

    2012-08-01

    Formation of pseudo-binary Fe-C-Si-B-P bulk metallic glasses (BMGs) with good glass-forming ability (GFA) and soft magnetic properties prepared using industrial pig-iron and P-Fe alloys as raw materials was investigated. It was found that the GFA could be enhanced by tuning the content of carbon, and fully glassy rods with a maximum diameter of 2 mm were obtained in the Fe77.3C5.9Si3.3B4.8P8.7 alloy. The crystallization behavior and its effects on the soft magnetic properties of the Fe77.3C5.9Si3.3B4.8P8.7 alloy were analyzed. The superior magnetic properties, coupled with large GFA and low cost of raw materials, make the current Fe-based BMGs promising for potential applications in electric industries.

  7. Proceedings of the Seventh Joint Magnetism and Magnetic Materials-Intermag Conference 6-9 January 1998 San Francisco, California Volume 83, Number 11, Part 2.

    Science.gov (United States)

    1998-06-01

    Jet Propulsion Laboratory, Pasadena, California 91109 Marc De Graefa) and Michael E. McHenry Department of Materials Science and Engineering...the magnetization D. Garcfa-Pablosa) and N. Garcia Laboratorio de Fisica de Sistemas Pequems y Nanotecnologia, Consejo Superior de Investigaciones...H. Fujiwara K. Klaassen A. Pohm Publications Committee R. R. Katti and J. M. MacLaren, Co-Chairmen Editors M. Alex J. Fernandez de Castro P

  8. Thermal and high magnetic field treatment of materials and associated apparatus

    Science.gov (United States)

    Kisner, Roger A.; Wilgen, John B.; Ludtka, Gerard M.; Jaramillo, Roger A.; Mackiewicz-Ludtka, Gail

    2007-01-09

    An apparatus and method for altering characteristics, such as can include structural, magnetic, electrical, optical or acoustical characteristics, of an electrically-conductive workpiece utilizes a magnetic field within which the workpiece is positionable and schemes for thermally treating the workpiece by heating or cooling techniques in conjunction with the generated magnetic field so that the characteristics of the workpiece are effected by both the generated magnetic field and the thermal treatment of the workpiece.

  9. Ordered mesoporous ferrosilicate materials with highly dispersed iron oxide nanoparticles and investigation of their unique magnetic properties.

    Science.gov (United States)

    Srinivasu, Pavuluri; Suresh, Koppoju; Datt, Gopal; Abhayankar, Ashutosh C; Rao, Pothuraju Nageswara; Lakshmi Kantam, Mannepalli; Bhargava, Suresh K; Tang, Jing; Yamauchi, Yusuke

    2014-11-07

    Ordered mesoporous ferrosilicate materials with highly dispersed iron oxide nanoparticles are directly synthesized through a hydrothermal approach under acidic conditions. The obtained samples possess a high surface area (up to 1236 m(2) g(-1)) and a large pore volume (up to 1.1 cm(3) g(-1)). By changing the amount of iron content, the magnetic properties can be tuned.

  10. Preparation of magnetic graphene @polydopamine @Zr-MOF material for the extraction and analysis of bisphenols in water samples.

    Science.gov (United States)

    Wang, Xianying; Deng, Chunhui

    2015-11-01

    In this work, a simple method for the extraction and analysis of bisphenols in environmental samples was presented. And the prepared zirconium-based magnetic MOFs (magG@PDA@Zr-MOF) were used as the sorbents for the magnetic solid-phase extraction. With the simple solvothermal reaction and sol-gel method, the prepared material showed great characteristics of large surface area, homogeneous pore size, good magnetic responsivity and super-hydrophilicity. The large surface area provided abundant sites to extract target compounds; the magnetic property could simplify the whole extraction procedure; and the hydrophilicity improved the dispersibility of the material in matrix. Here, various extraction parameters were optimized, including amounts of sorbents, adsorption time, species of elution solvents and desorption time. The whole extraction procedure could be accomplished in 30 min. And under the optimized conditions, method validations were also studied, such as linearity, the limit of detection and recovery. Finally, the prepared material was used in real water samples. The results showed this material had good potential as the sorbent for the extraction of targets in environmental water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Replacement and Original Magnet Engineering Options (ROMEOs): A European Seventh Framework Project to Develop Advanced Permanent Magnets Without, or with Reduced Use of, Critical Raw Materials

    Science.gov (United States)

    Mcguiness, P.; Akdogan, O.; Asali, A.; Bance, S.; Bittner, F.; Coey, J. M. D.; Dempsey, N. M.; Fidler, J.; Givord, D.; Gutfleisch, O.; Katter, M.; Le Roy, D.; Sanvito, S.; Schrefl, T.; Schultz, L.; Schwöbl, C.; Soderžnik, M.; Šturm, S.; Tozman, P.; Üstüner, K.; Venkatesan, M.; Woodcock, T. G.; Žagar, K.; Kobe, S.

    2015-06-01

    The rare-earth crisis, which peaked in the summer of 2011 with the prices of both light and heavy rare earths soaring to unprecedented levels, brought about the widespread realization that the long-term availability and price stability of rare earths could not be guaranteed. This triggered a rapid response from manufacturers involved in rare earths, as well as governments and national and international funding agencies. In the case of rare-earth-containing permanent magnets, three possibilities were given quick and serious consideration: (I) increased recycling of devices containing rare earths; (II) the search for new, mineable, rare-earth resources beyond those in China; and (III) the development of high-energy-product permanent magnets with little or no rare-earth content used in their manufacture. The Replacement and Original Magnet Engineering Options (ROMEO) project addresses the latter challenge using a two-pronged approach. With its basis on work packages that include materials modeling and advanced characterization, the ROMEO project is an attempt to develop a new class of novel permanent magnets that are free of rare earths. Furthermore, the project aims to minimize rare-earth content, particularly heavy-rare-earth (HRE) content, as much as possible in Nd-Fe-B-type magnets. Success has been achieved on both fronts. In terms of new, rare-earth-free magnets, a Heusler alloy database of 236,945 compounds has been narrowed down to approximately 20 new compounds. Of these compounds, Co2MnTi is expected to be a ferromagnet with a high Curie temperature and a high magnetic moment. Regarding the reduction in the amount of rare earths, and more specifically HREs, major progress is seen in electrophoretic deposition as a method for accurately positioning the HRE on the surface prior to its diffusion into the microstructure. This locally increases the coercivity of the rather small Nd-Fe-B-type magnet, thereby substantially reducing the dependence on the HREs Dy and

  12. Magnetic nanowires and hyperthermia: How geometry and material affect heat production efficiency

    KAUST Repository

    Contreras, Maria F.

    2015-05-01

    Magnetic hyperthermia, which refers to the production of heat by magnetic nanostructures under an alternating magnetic field (AMF), has been previously investigated with superparamagnetic nanobeads as a cancer therapy method. Magnetic nanowires (NWs) used in hyperthermia can be very promising, as it has been shown that they have a larger magnetic moment per unit of volume compared to the nanobeads. Moreover, Fe NWs proved to have a higher heating efficiency compared to Fe nanobeads, when exposed to an AMF at the same concentration [1].

  13. Development of references of anomalies detection on P91 material using Self-Magnetic Leakage Field (SMLF) technique

    Science.gov (United States)

    Husin, Shuib; Afiq Pauzi, Ahmad; Yunus, Salmi Mohd; Ghafar, Mohd Hafiz Abdul; Adilin Sekari, Saiful

    2017-10-01

    This technical paper demonstrates the successful of the application of self-magnetic leakage field (SMLF) technique in detecting anomalies in weldment of a thick P91 materials joint (1 inch thickness). Boiler components such as boiler tubes, stub boiler at penthouse and energy piping such as hot reheat pipe (HRP) and H-balance energy piping to turbine are made of P91 material. P91 is ferromagnetic material, therefore the technique of self-magnetic leakage field (SMLF) is applicable for P91 in detecting anomalies within material (internal defects). The technique is categorized under non-destructive technique (NDT). It is the second passive method after acoustic emission (AE), at which the information on structures radiation (magnetic field and energy waves) is used. The measured magnetic leakage field of a product or component is a magnetic leakage field occurring on the component’s surface in the zone of dislocation stable slipbands under the influence of operational (in-service) or residual stresses or in zones of maximum inhomogeneity of metal structure in new products or components. Inter-granular and trans-granular cracks, inclusion, void, cavity and corrosion are considered types of inhomogeneity and discontinuity in material where obviously the output of magnetic leakage field will be shown when using this technique. The technique does not required surface preparation for the component to be inspected. This technique is contact-type inspection, which means the sensor has to touch or in-contact to the component’s surface during inspection. The results of application of SMLF technique on the developed P91 reference blocks have demonstrated that the technique is practical to be used for anomaly inspection and detection as well as identification of anomalies’ location. The evaluation of this passive self-magnetic leakage field (SMLF) technique has been verified by other conventional non-destructive tests (NDTs) on the reference blocks where simulated

  14. Magnetic Materials: Novel Monitors of Long-Term Evolution of Engineered Barrier Systems

    Directory of Open Access Journals (Sweden)

    Simon L. Harley

    2016-12-01

    Full Text Available Most safety cases for the deep geological disposal of radioactive waste are reliant on the swelling of bentonite in the engineered barrier system as it saturates with groundwater. Assurance of safety therefore requires effective monitoring of bentonite saturation. The time- and fluid-dependent corrosion of synthetic magnets embedded in bentonite is demonstrated here to provide a novel and passive means of monitoring saturation. Experiments have been conducted at 70 °C in which neo magnets, AlNiCo magnets, and ferrite magnets have been reacted with saline (NaCl, KCl, CaCl2 solutions and alkaline fluids (NaOH, KOH, Ca(OH2 solutions; pH = 12 in the presence of bentonite. Nd-Fe-B magnets undergo extensive corrosion that results in a dramatic change from ferromagnetic to superparamagnetic behaviour concomitant with bentonite saturation. AlNiCo magnets in saline solutions show corrosion but only limited decreases in their magnetic intensities, and ferrite magnets are essentially unreactive on the experimental timescales, retaining their initial magnetic properties. For all magnets the impact of their corrosion on bentonite swelling is negligible; alteration of bentonite is essentially governed by the applied fluid composition. In principle, synthetic magnet arrays can, with further development, be designed and embedded in bentonite to monitor its fluid saturation without compromising the integrity of the engineered barrier system itself.

  15. Study of multi-layer active magnetic regenerators using magnetocaloric materials with first and second order phase transition

    DEFF Research Database (Denmark)

    Lei, Tian; Engelbrecht, Kurt; Nielsen, Kaspar Kirstein

    2016-01-01

    Magnetocaloric materials (MCM) with a first order phase transition (FOPT) usually exhibit a large, although sharp, isothermal entropy change near their Curie temperature, compared to materials with a second order phase transition (SOPT). Experimental results of applying FOPT materials in recent...... magnetocaloric refrigerators (MCR) demonstrated the great potential for these materials, but a thorough study on the impact of the moderate adiabatic temperature change and strong temperature dependence of the magnetocaloric effect (MCE) is lacking. Besides, comparing active magnetic regenerators (AMR) using...... FOPT and SOPT materials is also of fundamental interest. We present modeling results of multi-layer AMRs using FOPT and SOPT materials based on a 1D numerical model. First the impact of isothermal entropy change, adiabatic temperature change and shape factor describing the temperature dependence...

  16. A study of magnetic properties of hard and soft magnetic materials by Lorentz transmission electron microscopy and magnetic x-ray circular dichroism

    CERN Document Server

    Pickford, R A

    2001-01-01

    iron spin and orbital magnetic moments were found to decrease with increasing iron content. In collaboration with CEA Saclay, Paris, a set of cobalt elements were patterned by electron beam lithography. The elements were designed to isolate domain walls and to monitor their movement in an applied field. The shape anisotropy of the element was found to be too large for the insitu magnetic field to flip the magnetisation. The domain walls found in the as received magnetic state were associated with defects in the structure of the element. The magnetisation process was compared to micromagnetic simulations, A further study of magnetic elements was made to study the competition of anisotropy in patterned cobalt dots. The shape anisotropy was calculated and the crystalline anisotropy of the cobalt film was measured. The dots (rectangles) were patterned so that the shape anisotropy was comparable to the crystalline anisotropy of the cobalt. The dots were patterned at 45 degrees to the crystalline anisotropy. This t...

  17. Magnetic

    National Research Council Canada - National Science Library

    Essam Aboud; Nabil El-Masry; Atef Qaddah; Faisal Alqahtani; Mohammed R.H. Moufti

    2015-01-01

    .... A joint interpretation and inversion of gravity and magnetic data were used to estimate the thickness of the lava flows, delineate the subsurface structures of the study area, and estimate the depth...

  18. Portable magnetic tweezers device enables visualization of the three-dimensional microscale deformation of soft biological materials.

    Science.gov (United States)

    Yang, Yali; Lin, Jun; Meschewski, Ryan; Watson, Erin; Valentine, Megan T

    2011-07-01

    We have designed and built a magnetic tweezers device that enables the application of calibrated stresses to soft materials while simultaneously measuring their microscale deformation using confocal microscopy. Unlike previous magnetic tweezers designs, our device is entirely portable, allowing easy use on microscopes in core imaging facilities or in collaborators' laboratories. The imaging capabilities of the microscope are unimpaired, enabling the 3-D structures of fluorescently labeled materials to be precisely determined under applied load. With this device, we can apply a large range of forces (~1-1200 pN) over micron-scale contact areas to beads that are either embedded within 3-D matrices or attached to the surface of thin slab gels. To demonstrate the usefulness of this instrument, we have studied two important and biologically relevant materials: polyacrylamide-based hydrogel films typical of those used in cell traction force microscopy, and reconstituted networks of microtubules, essential cytoskeletal filaments.

  19. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      The magnet was energised at the beginning of March 2012 at a low current to check all the MSS safety chains. Then the magnet was ramped up to 3.8 T on 6 March 2012. Unfortunately two days later an unintentional switch OFF of the power converter caused a slow dump. This was due to a misunderstanding of the CCC (CERN Control Centre) concerning the procedure to apply for the CMS converter control according to the beam-mode status at that time. Following this event, the third one since 2009, a discussion was initiated to define possible improvement, not only on software and procedures in the CCC, but also to evaluate the possibility to upgrade the CMS hardware to prevent such discharge from occurring because of incorrect procedure implementations. The magnet operation itself was smooth, and no power cuts took place. As a result, the number of magnetic cycles was reduced to the minimum, with only two full magnetic cycles from 0 T to 3.8 T. Nevertheless the magnet suffered four stops of the cryogeni...

  20. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      Following the unexpected magnet stops last August due to sequences of unfortunate events on the services and cryogenics [see CMS internal report], a few more events and initiatives again disrupted the magnet operation. All the magnet parameters stayed at their nominal values during this period without any fault or alarm on the magnet control and safety systems. The magnet was stopped for the September technical stop to allow interventions in the experimental cavern on the detector services. On 1 October, to prepare the transfer of the liquid nitrogen tank on its new location, several control cables had to be removed. One cable was cut mistakenly, causing a digital input card to switch off, resulting in a cold-box (CB) stop. This tank is used for the pre-cooling of the magnet from room temperature down to 80 K, and for this reason it is controlled through the cryogenics control system. Since the connection of the CB was only allowed for a field below 2 T to avoid the risk of triggering a fast d...

  1. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    Operation of the magnet has gone quite smoothly during the first half of this year. The magnet has been at 4.5K for the full period since January. There was an unplanned short stop due to the CERN-wide power outage on May 28th, which caused a slow dump of the magnet. Since this occurred just before a planned technical stop of the LHC, during which access in the experimental cavern was authorized, it was decided to leave the magnet OFF until 2nd June, when magnet was ramped up again to 3.8T. The magnet system experienced a fault also resulting in a slow dump on April 14th. This was triggered by a thermostat on a filter choke in the 20kA DC power converter. The threshold of this thermostat is 65°C. However, no variation in the water-cooling flow rate or temperature was observed. Vibration may have been the root cause of the fault. All the thermostats have been checked, together with the cables, connectors and the read out card. The tightening of the inductance fixations has also been checked. More tem...

  2. Magnetism tuned by the charge states of defects in bulk C-doped SnO2 materials.

    Science.gov (United States)

    Lu, Ying-Bo; Ling, Z C; Cong, Wei-Yan; Zhang, Peng

    2015-10-21

    To analyze the controversial conclusions on the magnetism of C-doped SnO2 (SnO2:C) bulk materials between theoretical calculations and experimental observations, we propose the critical role of the charge states of defects in the geometric structures and magnetism, and carry out a series of first principle calculations. By changing the charge states, we can influence Bader charge distributions and atomic orbital occupancies in bulk SnO2:C systems, which consequently conduct magnetism. In all charged SnO2:C supercells, C-2px/py/pz electron occupancies are significantly changed by the charge self-regulation, and thus they make the C-2p orbitals spin polarized, which contribute to the dominant magnetic moment of the system. When the concentration of C dopant in the SnO2 supercell increases, the charge redistribution assigns extra electrons averagely to each dopant, and thus effectively modulates the magnetism. These findings provide an experimentally viable way for controlling the magnetism in these systems.

  3. Restricted access magnetic materials prepared by dual surface modification for selective extraction of therapeutic drugs from biological fluids

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yu; Wang Yuxia; Chen Lei [School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072 (China); Wan Qianhong, E-mail: qhwan@tju.edu.cn [School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072 (China)

    2012-02-15

    Magnetic porous particles with dual functionality have been prepared by a two-step procedure and evaluated as novel restricted access materials for extraction of therapeutic agents from biological fluids. The magnetic silica particles served as scaffolds were first modified with diol groups, which were then converted to octadecyl esters through reaction with stearoyl chloride. In the second step, the octadecyl esters on the exterior surface were hydrolyzed by the action of lipase to yield magnetic particles with hydrophobic reversed-phase ligands on the inner surface and biocompatible diol groups on the outer surface. The restricted access behavior of the resulting materials was confirmed by differential binding of small molecules such as methotrexate (MTX), leucovorin (LV) and folic acid (FA) relative to bovine serum albumin. While MTX, LV and FA were all bound to the magnetic particles with high affinity, the adsorption of the protein was markedly reduced due to size exclusion effect. The utility of the magnetic particles for sample preparation was tested in solid-phase extraction of MTX, LV and FA from spiked human serum and the effects of the SPE conditions on the recovery of the analytes were systematically studied. Moreover, the magnetic particle-based sample preparation procedure coupled with reversed-phase liquid chromatography analysis was validated in terms of specificity, linearity and reproducibility. The method was shown to be free from interference of endogenous compounds and linear over the concentration range of 0.5-10 {mu}g/mL for the three drugs studied. The limits of detection for the three drugs in serum were in the range of 0.160-0.302 {mu}g/mL. Reproducibility expressed as the RSD of the recovery for ten replicated extractions at three different concentrations was found to be less than 8.93%. With a unique combination of surface functionality with magnetic cores, the restricted access magnetic particles may be adapted in automated and high

  4. Bulk Combinatorial Synthesis and High Throughput Characterization for Rapid Assessment of Magnetic Materials: Application of Laser Engineered Net Shaping (LENS™)

    Science.gov (United States)

    Geng, J.; Nlebedim, I. C.; Besser, M. F.; Simsek, E.; Ott, R. T.

    2016-07-01

    A bulk combinatorial approach for synthesizing alloy libraries using laser engineered net shaping (LENS™; i.e., 3D printing) was utilized to rapidly assess material systems for magnetic applications. The LENS™ system feeds powders in different ratios into a melt pool created by a laser to synthesize samples with bulk (millimeters) dimensions. By analyzing these libraries with autosampler differential scanning calorimeter/thermal gravimetric analysis and vibrating sample magnetometry, we are able to rapidly characterize the thermodynamic and magnetic properties of the libraries. The Fe-Co binary alloy was used as a model system and the results were compared with data in the literature.

  5. Magnetic actuator based on giant magnetostrictive material Terfenol-D with strain and temperature monitoring using FBG optical sensor

    OpenAIRE

    García Miquel, Ángel Héctor; Barrera Vilar, David; Amat, Rafael; Kurlyandskaya, G. V.; Sales Maicas, Salvador

    2016-01-01

    We have designed a temperature and strain monitoring system for a magnetic actuator based on the giant magnetostrictive material Terfenol-D (Tb0.3 Dy0.7Fe1.92) with Fiber Bragg grating (FBG) sensors. Magneto-elastic properties of Terfenol-D depend on magnetization, stress pre-history, and temperature. In order to simultaneously monitor these effects, we have implemented a system based on a cylindrical Terfenol-D rod monitored with four FBGs that allows making the appropriate co...

  6. [Detection of Ethoprophos Using SERS Coupled with Magnetic Fe3O4/Ag Composite Materials].

    Science.gov (United States)

    Yuan, Rong-hui; Liu, Wen-han; Teng, Yuan-jie; Nie, Jing; Ma, Su-zhen

    2015-05-01

    The magnetic Fe3O4/Ag composite materials were synthesized by reducing AgNO3 with sodium citrate in the presence of Fe3O4 which were prepared by co-precipitation firstly. The enrichment and extraction of ethoprophos assembled on Fe3O4/Ag were achieved with the applied magnetic field. The different concentrations of ethoprophos adsorbed on Fe3O4/Ag were analyzed by SERS and it was showed that the trace analysis of ethoprophos had been established, while the enhancement factor of probe molecules on Fe3O4/Ag was 1. 48 X 10(5). The structure and morphology of Fe3O4/Ag were characterized by UV-Vis, EDX and TEM. Compared with Ag, the UV-Vis absorption peak of Fe3O4/Ag shifted from 417 to 369 nm, and the UV-Vis of Fe3O4 almost had no characteristic absorption peak in this region. At the same time, it was showed that the surface properties of Fe3O4/Ag changed with Raman enhancement effect during the aggregation process of Ag around the surface of Fe3O4. Further EDX images of micro area element analysis suggested that the chemical composition of products were Ag, Fe and O while the Cu peak was from the copper mesh. In addition, TEM images indicated that the average particle size of Fe3O4 was between 30 and 60 nm with shape tended to be spherical. And the silver nanoparticles were attached to the Fe3O4 particles and agglomeration occured. Density functional theory calculations which can be applied to qualitative judgment of molecule was carried out to obtain the molecular optimization structure and theoretical Raman spectra. It was found that the stabilized SERS signals were detected under the saturated adsorption equilibrium after 15 min. Finally, Raman response of ethoprophos was achieved with lower than 2 X 10(-8) mol . L-1 , indicatint that the established method had reached the requirements of ethoprophos residues detection and could be used for analysis of sulfur-containing organophosphorus pesticide.

  7. Removal of radioactive materials and heavy metals from water using magnetic resin

    Science.gov (United States)

    Kochen, Robert L.; Navratil, James D.

    1997-01-21

    Magnetic polymer resins capable of efficient removal of actinides and heavy metals from contaminated water are disclosed together with methods for making, using, and regenerating them. The resins comprise polyamine-epichlorohydrin resin beads with ferrites attached to the surfaces of the beads. Markedly improved water decontamination is demonstrated using these magnetic polymer resins of the invention in the presence of a magnetic field, as compared with water decontamination methods employing ordinary ion exchange resins or ferrites taken separately.

  8. Synthetic and Computational Approach on novel Transitional metal and 3d-4f Molecular Magnetic Materials

    OpenAIRE

    Radhakrishnan, Vignesh Kuduva

    2017-01-01

    This thesis deals with the design, synthesis, structures and modeling of spin-Hamiltonian parameters (such as J, D and g–tensors) in manganese complexes and mixed transition metal-lanthanide (3d-4f) based complexes using both experimental and computational tools. Certain mononuclear/polynuclear complexes are capable of retaining their magnetization even in the absence of magnetic field which gives rise to magnetic hysteresis at a molecular level and an ability to act as m...

  9. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      The magnet and its sub-systems were stopped at the beginning of the winter shutdown on 8th December 2011. The magnet was left without cooling during the cryogenics maintenance until 17th January 2012, when the cryoplant operation resumed. The magnet temperature reached 93 K. The vacuum pumping was maintained during this period. During this shutdown, the yearly maintenance was performed on the cryogenics, the vacuum pumps, the magnet control and safety systems, and the power converter and discharge lines. Several preventive actions led to the replacement of the electrovalve command coils, and the 20A DC power supplies of the magnet control system. The filters were cleaned on the demineralised water circuits. The oil of the diffusion pumps was changed. On the cryogenics, warm nitrogen at 343 K was circulated in the cold box to regenerate the filters and the heat exchangers. The coalescing filters have been replaced at the inlet of both the turbines and the lubricant trapping unit. The active cha...

  10. MAGNET

    CERN Multimedia

    B. Curé

    2011-01-01

    The CMS magnet has been running steadily and smoothly since the summer, with no detected flaw. The magnet instrumentation is entirely operational and all the parameters are at their nominal values. Three power cuts on the electrical network affected the magnet run in the past five months, with no impact on the data-taking as the accelerator was also affected at the same time. On 22nd June, a thunderstorm caused a power glitch on the service electrical network. The primary water cooling at Point 5 was stopped. Despite a quick restart of the water cooling, the inlet temperature of the demineralised water on the busbar cooling circuit increased by 5 °C, up to 23.3 °C. It was kept below the threshold of 27 °C by switching off other cooling circuits to avoid the trigger of a slow dump of the magnet. The cold box of the cryogenics also stopped. Part of the spare liquid helium volume was used to maintain the cooling of the magnet at 4.5 K. The operators of the cryogenics quickly restarted ...

  11. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    The magnet was successfully operated at the end of the year 2009 despite some technical problems on the cryogenics. The magnet was ramped up to 3.8 T at the end of November until December 16th when the shutdown started. The magnet operation met a few unexpected stops. The field was reduced to 3.5 T for about 5 hours on December 3rd due to a faulty pressure sensor on the helium compressor. The following day the CERN CCC stopped unintentionally the power converters of the LHC and the experiments, triggering a ramp down that was stopped at 2.7 T. The magnet was back at 3.8 T about 6 hours after CCC sent the CERN-wide command. Three days later, a slow dump was triggered due to a stop of the pump feeding the power converter water-cooling circuit, during an intervention on the water-cooling plant done after several disturbances on the electrical distribution network. The magnet was back at 3.8 T in the evening the same day. On December 10th a break occurred in one turbine of the cold box producing the liquid ...

  12. MAGNET

    CERN Multimedia

    B. Curé

    2013-01-01

      The magnet was operated without any problem until the end of the LHC run in February 2013, apart from a CERN-wide power glitch on 10 January 2013 that affected the CMS refrigerator, causing a ramp down to 2 T in order to reconnect the coldbox. Another CERN-wide power glitch on 15 January 2013 didn’t affect the magnet subsystems, the cryoplant or the power converter. At the end of the magnet run, the reconnection of the coldbox at 2.5 T was tested. The process will be updated, in particular the parameters of some PID valve controllers. The helium flow of the current leads was reduced but only for a few seconds. The exercise will be repeated with the revised parameters to validate the automatic reconnection process of the coldbox. During LS1, the water-cooling services will be reduced and many interventions are planned on the electrical services. Therefore, the magnet cryogenics and subsystems will be stopped for several months, and the magnet cannot be kept cold. In order to avoid unc...

  13. High-performance magnetic carbon materials in dye removal from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Xiaoming, E-mail: dawn1026@163.com; Zhang, Yu; Dai, Yuan; Fu, Feng, E-mail: yadxfufeng@126.com

    2016-07-15

    To obtain a novel adsorbent with excellent adsorption capacity and convenient magnetic separation property, magnetic activated semi-coke was prepared by KOH activation method and further modified by FeCl{sub 3}. The surface morphology, physical structure, chemical properties and textural characteristics of unmodified semi-coke, KOH-modified semi-coke and magnetic activated semi-coke were characterized by scanning electron microscopy, X-ray powder diffraction, N{sub 2} adsorption-desorption measurement, and electronic differential system. The adsorption characteristics of the magnetic activated semi-coke were explored for the removal of methyl orang (MO), methylene blue (MB), congo red (CR), acid fuchsin (AF), and rhodamine B (RB) from aqueous solution. The effects of adsorption parameters, including adsorbent dosage, pH and contact time, were investigated by comparing the adsorption properties of the magnetic activated semi-coke to RB. The result showed that the magnetic activated semi-coke displayed excellent dispersion, convenient separation and high adsorption capacity. The adsorption experiment data indicated that the pseudosecond order model and the Langmuir model could well explain the adsorption processes of RB on the magnetic activated semi-coke, and the maximum adsorption capacity (q{sub m}) was 526.32 mg/g. The values of thermodynamic parameters (ΔG°, ΔH° and ΔS°) indicated that the adsorption process depended on the temperature of the aqueous phase, and it was spontaneous and exothermic in nature. As the addition of the magnetic activated semi-coke, the color of the solution significantly faded. Subsequently, fast aggregation of the magnetic activated semi-coke from their homogeneous dispersion in the presence of an external magnetic field could be happened. So, the magnetic activated semi-coke displayed excellent dispersion, convenient separation and high adsorption capacity. - Graphical abstract: As the addition of the magnetic activated semi

  14. The QUAX proposal: a search of galactic axion with magnetic materials

    CERN Document Server

    Ruoso, Giuseppe; Ortolan, Antonello; Pengo, Ruggero; Braggio, Caterina; Carugno, Giovanni; Gallo, Carmelo Sebastiano; Speake, Clive C.

    2016-06-09

    Aim of the QUAX (QUaerere AXion) proposal is to exploit the interaction of cosmological axions with the spin of electrons in a magnetized sample. Their effect is equivalent to the application of an oscillating rf field with frequency and amplitude which are fixed by axion mass and coupling constant, respectively. The rf receiver module of the QUAX detector consists of magnetized samples with the Larmor resonance frequency tuned to the axion mass by a polarizing static magnetic field. The interaction of electrons with the axion-equivalent rf field produces oscillations in the total magnetization of the samples. To amplify such a tiny field, a pump field at the same frequency is applied in a direction orthogonal to the polarizing field. The induced oscillatory magnetization along the polarizing field is measured by a SQUID amplifier operated at its quantum noise level.

  15. MAGNET

    CERN Multimedia

    B. Curé

    2011-01-01

    The magnet ran smoothly in the last few months until a fast dump occurred on 9th May 2011. Fortunately, this occurred in the afternoon of the first day of the technical stop. The fast dump was due to a valve position controller that caused the sudden closure of a valve. This valve is used to regulate the helium flow on one of the two current leads, which electrically connects the coil at 4.5 K to the busbars at room temperature. With no helium flow on the lead, the voltage drop and the temperatures across the leads increase up to the defined thresholds, triggering a fast dump through the Magnet Safety System (MSS). The automatic reaction triggered by the MSS worked properly. The helium release was limited as the pressure rise was just at the limit of the safety valve opening pressure. The average temperature of the magnet reached 72 K. It took four days to recover the temperature and refill the helium volumes. The faulty valve controller was replaced by a spare one before the magnet ramp-up resumed....

  16. Searching the conditions for a table-like shape of the magnetic entropy in magneto-caloric materials

    Energy Technology Data Exchange (ETDEWEB)

    Álvarez, Pablo, E-mail: pablo.alvarez@ehu.es [Departamento de Electricidad y Electrónica, Universidad del País Vasco (UPV/EHU), 48940 Leioa (Spain); Departamento de Física, Universidad de Oviedo, c/ Calvo Sotelo, s/n, 33007 Oviedo (Spain); Gorria, Pedro, E-mail: pgorria@uniovi.es [Departamento de Física, Universidad de Oviedo, c/ Calvo Sotelo, s/n, 33007 Oviedo (Spain); Sánchez Llamazares, José L. [División de Materiales Avanzados, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la presa San José 2055, CP 78216 San Luis Potosí (Mexico); Blanco, Jesús A. [Departamento de Física, Universidad de Oviedo, c/ Calvo Sotelo, s/n, 33007 Oviedo (Spain)

    2013-08-15

    Highlights: •The magnetic entropy change for two-ribbon (amorphous) composite materials is investigated. •The conditions to obtain a table-like shape of the magnetic entropy change are specified. •We give the essential ingredients to maximize the effective refrigerant capacity and the efficiency. •Our findings could be used in other magneto-caloric materials to tune the temperature range for the table-like behavior. -- Abstract: We show a systematic study of the magneto-caloric response carried out on a series of FeZrB(Cu) amorphous ribbons with different Curie temperature values in the 210–320 K interval. The main aim of the work is to investigate the conditions to obtain, from the isothermal magnetic entropy change vs. temperature curves, ΔS{sub M}(T), a table-like behavior of the entropy using two-ribbon composites. Even though the maximum value of ΔS{sub M} for the composite is lower than those of the single components, the existence of a table-like behavior maximizes the effective refrigerant capacity, reaching values around 80 J/kg for an applied magnetic field change of 2 T. Furthermore, we discuss how the temperature range for such a table-like behavior can be tuned and the refrigerant capacity enhanced in terms of energy efficiency.

  17. Study of multi-layer active magnetic regenerators using magnetocaloric materials with first and second order phase transition

    Science.gov (United States)

    Lei, T.; Engelbrecht, K.; Nielsen, K. K.; Neves Bez, H.; Bahl, C. R. H.

    2016-09-01

    Magnetocaloric materials (MCM) with a first order phase transition (FOPT) usually exhibit a large, although sharp, isothermal entropy change near their Curie temperature, compared to materials with a second order phase transition (SOPT). Experimental results of applying FOPT materials in recent magnetocaloric refrigerators (MCR) demonstrated the great potential for these materials, but a thorough study on the impact of the moderate adiabatic temperature change and strong temperature dependence of the magnetocaloric effect (MCE) is lacking. Besides, comparing active magnetic regenerators (AMR) using FOPT and SOPT materials is also of fundamental interest. We present modeling results of multi-layer AMRs using FOPT and SOPT materials based on a 1D numerical model. First the impact of isothermal entropy change, adiabatic temperature change and shape factor describing the temperature dependence of the MCE are quantified and analyzed by using artificially built magnetocaloric properties. Then, based on measured magnetocaloric properties of La(Fe,Mn,Si)13H y and Gd, an investigation on how to layer typical FOPT and SOPT materials with different temperature spans is carried out. Moreover, the sensitivity of variation in Curie temperature distribution for both groups of AMRs is investigated. Finally, a concept of mixing FOPT and SOPT materials is studied for improving the stability of layered AMRs with existing materials.

  18. Discrimination of Terrestrial Source Materials to the Northern North Atlantic Using Particle Size Specific Magnetic Measurements and Electron Microscopy.

    Science.gov (United States)

    Hatfield, R. G.; Stoner, J. S.; Tepley, F. J., III

    2015-12-01

    We investigate the magnetic properties of different terrestrial sediment fractions (sand, silt, and clay) from Iceland and Greenland as major sediment sources to the northern North Atlantic (NNA). Magnetic susceptibility (MS) and hysteresis data have previously shown to be strongly particle size dependent with silt (3-63μm) important for hosting the ferrimagnetic fraction and discriminating source. Here we expand upon these data with more fundamental observations including low temperature remanence, low and high temperature MS, and electron microscopy. All Iceland fractions lack a Verwey transition (Tv) and MS decreases gradually on heating between 100-500°C, consistent with (TM60) titanomagnetite. Frequency dependent MS (fd%; 1-998 Hz) of ~8% across all Iceland fractions implies significant SP grain populations within the average Day plot determined PSD grain size. Homogeneity in magnetic grain size across all Icelandic fractions implies a disconnect with physical grain size that is visualized in electron backscatter images as fine Fe-rich fragments are included within larger host grains. In contrast Greenlandic silt and sand possess a strong Tv and MS values that fall steeply between 560-580°C on heating, consistent with magnetite. Greenlandic ferrimagnetic fragments within the silt and sand size fractions exist as discrete particles and average magnetic grain size scales with physical grain size; the sand fraction is dominated by MD grains and silts are coarse PSD in size. While finer PSD clays are indistinguishable from all Iceland fractions on a Day plot SP contributions are lower and the Tv is more pronounced in Greenland clay. These new magnetic mineralogy, magnetic grain size, and electron microscopy measurements expand the differentiation of source and grain size of NNA source materials, and further highlight the necessity for grain-size specific magnetic measurements to isolate source from physical grain size variation in bulk marine sediment cores.

  19. Magnetic Ganoderma lucidum spore microspheres: A novel material to immobilize CotA multicopper oxidase for dye decolorization

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Lili [School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wang, Yan, E-mail: wangy_msn@hit.edu.cn [School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhao, Min [College of Life Science, Northeast Forestry University, Harbin 150040 (China); Song, Jinzhu [School of Life Science and Technology, Harbin Institute of Technology, Harbin 150001 (China); Wang, Jueyu; Jin, Zijing [College of Life Science, Northeast Forestry University, Harbin 150040 (China)

    2016-08-05

    Highlights: • Hollow microspheres were obtained from Ganoderma lucidum spores. • Novel magnetic microspheres were prepared by load hollow spore microspheres with Fe{sub 3}O{sub 4} nanoparticles. • CotA multicopper oxidase was immobilized on the magnetic spore microspheres for indigo carmine decolorization. • The immobilized CotA displayed higher decolorization capability and reusability. - Abstract: In this study, hollow microspheres were obtained from Ganoderma lucidum spores. Then the hollow microspheres were loaded with Fe{sub 3}O{sub 4} nanoparticles to prepare novel magnetic spore microspheres. TEM images and X-ray diffractometry demonstrated that the Fe{sub 3}O{sub 4} nanoparticles were incorporated throughout the spore microsphere. CotA multicopper oxidase was chosen as biomacromolecule to study the loading ability of the magnetic spore microspheres. The combination of the CotA enzyme with the microsphere was observed by laser scanning confocal microscope. The loaded amount of CotA on the microspheres was 75 mg/g when the CotA concentration was 1.2 mg/mL and the activity recovery of the immobilized CotA was 81%. The magnetic microspheres loaded with CotA, which can be easily and quickly recovered by an external magnetic field, were used for dye decolorization. After 1 h decolorization, 99% of the indigo carmine has been removed by 10 mg microspheres. In addition, the immobilized CotA retained 75% of activity after 10 consecutive cycles, which indicated that the magnetic spore microspheres are good support material for immobilization of the enzyme.

  20. Two phase modeling of the influence of plastic strain on the magnetic and magnetostrictive behaviors of ferromagnetic materials

    Science.gov (United States)

    Hubert, Olivier; Lazreg, Said

    2017-02-01

    A growing interest of automotive industry in the use of high performance steels is observed. These materials are obtained thanks to complex manufacturing processes whose parameters fluctuations lead to strong variations of microstructure and mechanical properties. The on-line magnetic non-destructive monitoring is a relevant response to this problem but it requires fast models sensitive to different parameters of the forming process. The plastic deformation is one of these important parameters. Indeed, ferromagnetic materials are known to be sensitive to stress application and especially to plastic strains. In this paper, a macroscopic approach using the kinematic hardening is proposed to model this behavior, considering a plastic strained material as a two phase system. Relationship between kinematic hardening and residual stress is defined in this framework. Since stress fields are multiaxial, an uniaxial equivalent stress is calculated and introduced inside the so-called magneto-mechanical multidomain modeling to represent the effect of plastic strain. The modeling approach is complemented by many experiments involving magnetic and magnetostrictive measurements. They are carried out with or without applied stress, using a dual-phase steel deformed at different levels. The main interest of this material is that the mechanically hard phase, soft phase and the kinematic hardening can be clearly identified thanks to simple experiments. It is shown how this model can be extended to single phase materials.

  1. MAGNET

    CERN Multimedia

    B. Curé

    MAGNET During the winter shutdown, the magnet subsystems went through a full maintenance. The magnet was successfully warmed up to room temperature beginning of December 2008. The vacuum was broken later on by injecting nitrogen at a pressure just above one atmosphere inside the vacuum tank. This was necessary both to prevent any accidental humidity ingress, and to allow for a modification of the vacuum gauges on the vacuum tank and maintenance of the diffusion pumps. The vacuum gauges had to be changed, because of erratic variations on the measurements, causing spurious alarms. The new type of vacuum gauges has been used in similar conditions on the other LHC experiments and without problems. They are shielded against the stray field. The lubricants of the primary and diffusion pumps have been changed. Several minor modifications were also carried out on the equipment in the service cavern, with the aim to ease the maintenance and to allow possible intervention during operation. Spare sensors have been bough...

  2. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    The magnet worked very well at 3.8 T as expected, despite a technical issue that manifested twice in the cryogenics since June. All the other magnet sub-systems worked without flaw. The issue in the cryogenics was with the cold box: it could be observed that the cold box was getting progressively blocked, due to some residual humidity and air accumulating in the first thermal exchanger and in the adsorber at 65 K. This was later confirmed by the analysis during the regeneration phases. An increase in the temperature difference between the helium inlet and outlet across the heat exchanger and a pressure drop increase on the filter of the adsorber were observed. The consequence was a reduction of the helium flow, first compensated by the automatic opening of the regulation valves. But once they were fully opened, the flow and refrigeration power reduced as a consequence. In such a situation, the liquid helium level in the helium Dewar decreased, eventually causing a ramp down of the magnet current and a field...

  3. MAGNET

    CERN Multimedia

    Benoit Curé.

    The magnet operation restarted end of June this year. Quick routine checks of the magnet sub-systems were performed at low current before starting the ramps up to higher field. It appeared clearly that the end of the field ramp down to zero was too long to be compatible with the detector commissioning and operations plans. It was decided to perform an upgrade to keep the ramp down from 3.8T to zero within 4 hours. On July 10th, when a field of 1.5T was reached, small movements were observed in the forward region support table and it was decided to fix this problem before going to higher field. At the end of July the ramps could be resumed. On July 28th, the field was at 3.8T and the summer CRAFT exercise could start. This run in August went smoothly until a general CERN wide power cut took place on August 3rd, due to an insulation fault on the high voltage network outside point 5. It affected the magnet powering electrical circuit, as it caused the opening of the main circuit breakers, resulting in a fast du...

  4. MAGNET

    CERN Multimedia

    B. Curé

    2013-01-01

    The magnet is fully stopped and at room temperature. The maintenance works and consolidation activities on the magnet sub-systems are progressing. To consolidate the cryogenic installation, two redundant helium compressors will be installed as ‘hot spares’, to avoid the risk of a magnet downtime in case of a major failure of a compressor unit during operation. The screw compressors, their motors, the mechanical couplings and the concrete blocks are already available and stored at P5. The metallic structure used to access the existing compressors in SH5 will be modified to allow the installation of the two redundant ones. The plan is to finish the installation and commissioning of the hot spare compressors before the summer 2014. In the meantime, a bypass on the high-pressure helium piping will be installed for the connection of a helium drier unit later during the Long Shutdown 1, keeping this installation out of the schedule critical path. A proposal is now being prepared for the con...

  5. Commercial-scale recycling of NdFeB-type magnets with grain boundary modification yields products with 'designer properties' that exceed those of starting materials.

    Science.gov (United States)

    Zakotnik, M; Tudor, C O

    2015-10-01

    NdFeB-type magnets dominate the market for high performance magnetic materials, yet production of 'virgin' magnets via mining is environmentally, financially and energetically costly. Hence, interest is growing in 'magnet to magnet' recycling schemes that offer the potential for cheaper, more environmentally-friendly solutions to the world's growing appetite for rare-earth based magnetic materials. Unfortunately, previously described recycling processes only partially capitalise on this potential, because the methods described to date are limited to 'laboratory scale' or operate only under ideal conditions and result in products that fail to recapture the coercivity of the starting, scrap materials. Herein, we report a commercial scale process (120 kg batches) that completely recovers the properties of the starting scrap magnets. Indeed, 'grain boundary modification', via careful addition of a proprietary mix of blended elements, produces magnets with 'designer properties' that can exceed those of the starting materials and can be closely tailored to meet a wide variety of end-user applications, including high-coercivity (>2000 kA/m), sintered magnets suitable for motor applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Development of Novel Magnetic Metal Oxide Thin Films and Carbon Nanotube Materials for Potential Device Applications

    Science.gov (United States)

    2016-05-09

    D: Appl. Phys. 42, 175006 (2009). 9. A. I. Schindler and C. M. Williams, Investigations of the Effects of Neutron and He3 Irradiation on the...a bulk-line situation to a configuration where low dimensionality effects are significant [25]. Salvador et. al. [26] showed that for uncapped films...of the loop at the zero magnetization axes. Lopez- Urias, et. al. [35] reported formation of helical spin configurations during magnetization of

  7. Fabrication and magnetic properties of granular Co/porous InP nanocomposite materials

    Directory of Open Access Journals (Sweden)

    Ma Li

    2011-01-01

    Full Text Available Abstract A novel Co/InP magnetic semiconductor nanocomposite was fabricated by electrodeposition magnetic Co nanoparticles into n-type porous InP templates in ethanol solution of cobalt chloride. The content or particle size of Co particles embedded in porous InP increased with increasing deposition time. Co particles had uniform distribution over pore sidewall surface of InP template, which was different from that of ceramic template and may open up new branch of fabrication of nanocomposites. The magnetism of such Co/InP nanocomposites can be gradually tuned from diamagnetism to ferromagnetism by increasing the deposition time of Co. Magnetic anisotropy of this Co/InP nanocomposite with magnetization easy axis along the axis of InP square channel was well realized by the competition between shape anisotropy and magnetocrystalline anisotropy. Such Co/InP nanocomposites with adjustable magnetism may have potential applications in future in the field of spin electronics. PACS: 61.46. +w · 72.80.Tm · 81.05.Rm · 75.75. +a · 82.45.Aa

  8. Fabrication and magnetic properties of granular Co/porous InP nanocomposite materials

    Science.gov (United States)

    2011-01-01

    A novel Co/InP magnetic semiconductor nanocomposite was fabricated by electrodeposition magnetic Co nanoparticles into n-type porous InP templates in ethanol solution of cobalt chloride. The content or particle size of Co particles embedded in porous InP increased with increasing deposition time. Co particles had uniform distribution over pore sidewall surface of InP template, which was different from that of ceramic template and may open up new branch of fabrication of nanocomposites. The magnetism of such Co/InP nanocomposites can be gradually tuned from diamagnetism to ferromagnetism by increasing the deposition time of Co. Magnetic anisotropy of this Co/InP nanocomposite with magnetization easy axis along the axis of InP square channel was well realized by the competition between shape anisotropy and magnetocrystalline anisotropy. Such Co/InP nanocomposites with adjustable magnetism may have potential applications in future in the field of spin electronics. PACS: 61.46. +w · 72.80.Tm · 81.05.Rm · 75.75. +a · 82.45.Aa PMID:21711809

  9. Study of magnetic properties of graphene nanostructures and graphene nanoribbons

    Directory of Open Access Journals (Sweden)

    F Fazileh

    2012-03-01

    Full Text Available The discovery of graphene and its remarkable electronic and magnetic properties has initiated great research interest in this material. Furthermore, there are many derivatives in these graphene related materials among which graphene nanoribbons and graphene nanofragments are candidates for future carbon-based nanoelectronics and spintronics. Theoretical studies have shown that magnetism can arise in various situations such as point defects, disorder and reduced dimensionality. Using a mean field Hubbard model, we studied the appearance of magnetic textures in zero-dimensional graphene nanofragments and one-dimensional graphene zigzag nanoribbons. Among nanofragments, triangular shape, bowtie and coronene were studied. We explain how the shape of these materials, the imbalance in the number of atoms belonging to the graphene sublattices, the existence of zero-energy states and the total and local magnetic moments were related. At the end, we focused on the effects of a model disorder potential (Anderson-type, and illustrate how density of states of zigzag nanoribbons was affected.

  10. Preliminary experiments about the measure of the magnetic properties of a material by means of TDR probes

    Science.gov (United States)

    Persico, Raffaele

    2016-04-01

    In this contribution, the possibility of measuring possible magnetic properties of materials by means of a TDR probe is studied. A transmission line model is adopted and data in time and frequency domain are exploited together. Simulation results are shown, at the moment based on a bifilar line model. Magnetic properties of materials can be of interest for several applications. In particular, the presence of magnetic features in the soil or in any substance, might be associated to some contaminant (presumably containing some metallic element as iron, nickel or chromium [1]). This kind of pollution might occur close to some farms, especially regarding the dying of dresses, the production of some medicines, the tanning of leather issues. Moreover, modern agriculture puts in the soil several fertilizing substances, and there is a debate about the quantity of heavy metals spread in the terrain by these activities [2]. Still, some depuration-mud can be affected by an excessive presence of metallic elements, because of the presence of batteries, skins, varnishes, cosmetics, and so on [2]. Moreover, it is thought that the soil on the planet Mars might show magnetic properties [3]. Finally, in GPR prospecting, possible magnetic characteristics of the soil or of the targets might be of interest too [4], but they cannot be retrieved by means of only GPR data [5]. In the present paper, the results of a preliminary study are exposed with regard to the possibility to measure the magnetic properties of a material by mean of a TDR probe [6-7]. In particular a TDR probe is essentially a transmission line (a bifilar model will be exploited in this work) open at the end, form which most of the impinging energy (ideally the whole of thi energy in a lossless medium) is back reflected. In particular, this allows a customary measure of the propagation velocity in the medium if an impulsive signal is generated. In fact, the return time along a path of known length is measured. The

  11. Magnetic Abrasive Machining of Difficult-to-Cut Materials for Ultra-High-Speed Machining of AISI 304 Bars

    Directory of Open Access Journals (Sweden)

    Rui Wang

    2017-09-01

    Full Text Available This research proposes an optimized magnetic abrasive machining process that uses an ultra-high-speed system to perform precision machining on a workpiece. The system can process several microns of material, either for machining surface roughness or for machining a workpiece for a precise micro-diameter. The stainless steel workpieces have been machined using an ultra-high-speed magnetic abrasive machining (UHSMAM process. The experiments were performed analyzing the accuracy of the machined workpiece diameter, using response surface methodology. The results obtained after machining have been analyzed to determine the effect of different process parameters such as machining speed, machining time, machining frequencies, inert gas in/out, magnetic pole types, and magnetic abrasive mesh size for the individual workpiece, as well as to study various interaction effects that may significantly affect the machining performance of the process. The obtained outcomes of the analysis for different workpieces have been critically compared to understand the effect of the considered process parameters based on the resulting mechanical properties. Regression analysis was used to confirm the stability of the micro-diameter and the processing efficiency. Atomic force microscope (AFM micrographs were also obtained to study the surface morphology of the precision-machined workpiece.

  12. Magnetic Abrasive Machining of Difficult-to-Cut Materials for Ultra-High-Speed Machining of AISI 304 Bars.

    Science.gov (United States)

    Wang, Rui; Lim, Pyo; Heng, Lida; Mun, Sang Don

    2017-09-04

    This research proposes an optimized magnetic abrasive machining process that uses an ultra-high-speed system to perform precision machining on a workpiece. The system can process several microns of material, either for machining surface roughness or for machining a workpiece for a precise micro-diameter. The stainless steel workpieces have been machined using an ultra-high-speed magnetic abrasive machining (UHSMAM) process. The experiments were performed analyzing the accuracy of the machined workpiece diameter, using response surface methodology. The results obtained after machining have been analyzed to determine the effect of different process parameters such as machining speed, machining time, machining frequencies, inert gas in/out, magnetic pole types, and magnetic abrasive mesh size for the individual workpiece, as well as to study various interaction effects that may significantly affect the machining performance of the process. The obtained outcomes of the analysis for different workpieces have been critically compared to understand the effect of the considered process parameters based on the resulting mechanical properties. Regression analysis was used to confirm the stability of the micro-diameter and the processing efficiency. Atomic force microscope (AFM) micrographs were also obtained to study the surface morphology of the precision-machined workpiece.

  13. Soft X-ray microscopy to 25 nm with applications to biology and magnetic materials

    CERN Document Server

    Denbeaux, G; Chao, W; Eimueller, T; Johnson, L; Köhler, M; Larabell, C; Legros, M; Fischer, P; Pearson, A; Schuetz, G; Yager, D; Attwood, D

    2001-01-01

    We report both technical advances in soft X-ray microscopy (XRM) and applications furthered by these advances. With new zone plate lenses we record test pattern features with good modulation to 25 nm and smaller. In combination with fast cryofixation, sub-cellular images show very fine detail previously seen only in electron microscopy, but seen here in thick, hydrated, and unstained samples. The magnetic domain structure is studied at high spatial resolution with X-ray magnetic circular dichroism (X-MCD) as a huge element-specific magnetic contrast mechanism, occurring e.g. at the L sub 2 sub , sub 3 edges of transition metals. It can be used to distinguish between in-plane and out-of-plane contributions by tilting the sample. As XRM is a photon based technique, the magnetic images can be obtained in unlimited varying external magnetic fields. The images discussed have been obtained at the XM-1 soft X-ray microscope on beamline 6.1 at the Advanced Light Source in Berkeley.

  14. Electrochemical synthesis of nanostructured porous materials using liquid crystal and colloidal templates and their magnetic and optical properties

    CERN Document Server

    Ghanem, M A M

    2002-01-01

    material, and that these magnetic properties vary systematically with the diameter of the spherical pores within the films. A new oscillation effect has been observed for the coercivity of macroporous Ni sub 8 sub 0 Fe sub 2 sub 0 film with different pore layer thickness. sphere templates, the resulting films show well-formed, regular, two- and three-dimensional macroporous networks consisting of spherical pores arranged in a highly ordered face centred cubic (fee) structure. The spherical voids are interconnected by a series of smaller windows that form an open porous structure embedded in the material framework. The diameter of the spherical pores can be precisely changed over the range from 200 to 1000 nm by changing the diameter of the latex spheres used to form the templates. The resulting macroporous material structures are robust, self-supported, dense, polycrystalline, uniform and free from filling defects and contamination or problems caused by shrinkage during processing. The nanostructured macropor...

  15. MAGNET

    CERN Multimedia

    Benoit Curé

    The magnet subsystems resumed operation early this spring. The vacuum pumping was restarted mid March, and the cryogenic power plant was restarted on March 30th. Three and a half weeks later, the magnet was at 4.5 K. The vacuum pumping system is performing well. One of the newly installed vacuum gauges had to be replaced at the end of the cool-down phase, as the values indicated were not coherent with the other pressure measurements. The correction had to be implemented quickly to be sure no helium leak could be at the origin of this anomaly. The pressure measurements have been stable and coherent since the change. The cryogenics worked well, and the cool-down went quite smoothly, without any particular difficulty. The automated start of the turbines had to be fine-tuned to get a smooth transition, as it was observed that the cooling power delivered by the turbines was slightly higher than needed, causing the cold box to stop automatically. This had no consequence as the cold box safety system acts to keep ...

  16. MAGNET

    CERN Multimedia

    B. Curé

    During the winter shutdown, the magnet subsystems went through a full maintenance. The magnet was successfully warmed up to room temperature beginning of December 2008. The vacuum was broken later on by injecting nitrogen at a pressure just above one atmosphere inside the vacuum tank. This was necessary both to prevent any accidental humidity ingress, and to allow for a modification of the vacuum gauges on the vacuum tank and maintenance of the diffusion pumps. The vacuum gauges had to be changed, because of erratic variations on the measurements, causing spurious alarms. The new type of vacuum gauges has been used in similar conditions on the other LHC experiments and without problems. They are shielded against the stray field. The lubricants of the primary and diffusion pumps have been changed. Several minor modifications were also carried out on the equipment in the service cavern, with the aim to ease the maintenance and to allow possible intervention during operation. Spare sensors have been bought. Th...

  17. Single-sided magnetic resonance profiling in biological and materials science.

    Science.gov (United States)

    Danieli, Ernesto; Blümich, Bernhard

    2013-04-01

    Single-sided NMR was inspired by the oil industry that strived to improve the performance of well-logging tools to measure the properties of fluids confined downhole. This unconventional way of implementing NMR, in which stray magnetic and radio frequency fields are used to recover information of arbitrarily large objects placed outside the magnet, motivated the development of handheld NMR sensors. These devices have moved the technique to different scientific disciplines. The current work gives a review of the most relevant magnets and methodologies developed to generate NMR information from spatially localized regions of samples placed in close proximity to the sensors. When carried out systematically, such measurements lead to 'single-sided depth profiles' or one-dimensional images. This paper presents recent and most relevant applications as well as future perspectives of this growing branch of MRI. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. Nanocomposite Materials alfa-Fe2O3 / gamma-Fe2O3:Synthesis, Crystal and Magnetic Microstructure, Morphology

    OpenAIRE

    V.О. Kotsyubynsky; V.V. Mokliak; A.B.Grubiak; P.I. Kolkovsky; Al-Saedi Abdul Halek Zamil

    2013-01-01

    The paper studies the relationship between the synthesis conditions of nanocomposites α-Fe2O3 /  γ-Fe2O3 and the phase composition, morphology, crystal and magnetic microstructures of these materials.

  19. An Efficient Methodology for the Analysis of Dielectric Shimming Materials in Magnetic Resonance Imaging

    NARCIS (Netherlands)

    van Gemert, J.H.F.; Brink, Wyger M.; Webb, Andrew G.; Remis, R.F.

    2017-01-01

    Interference effects in the transmit $B_{1}^{+}$ field can severely degrade the image quality in high-field Magnetic Resonance Imaging (MRI). High-permittivity pads are increasingly used to counteract these effects, but designing such pads is not trivial. In this paper, we present an efficient

  20. Properties of a new magnetic material: Sr 2 FeMoO 6

    Indian Academy of Sciences (India)

    Recently, there have been a large number of investigations of the physical properties of Sr2FeMoO6 and related compounds, in view of their significant negative magnetoresistive property at room temperature and in low applied magnetic fields. We review these investigations, detailing the microscopic mechanism ...

  1. Scientific Articles on Magnetic Materials and Applications Research from 2006 - 2014

    Science.gov (United States)

    2015-03-01

    magnetic applications were for power applications. These power applications include inductors, transformers, electric motors , generators, actuators...equation is P = AfαBβ` (1) where P is power los (W/kg), A is the fitting coefficient, f is the frequency (kHz) and B is the flux density ( Tesla ) and α

  2. The effect of substrate materials on the structuraland magnetic properties of Co-Cr recording media

    NARCIS (Netherlands)

    ten Berge, Peter; ten Berge, P.

    1992-01-01

    The investigations described in this thesis deal with the influence of substrates and seedlayers on the structural and magnetic properties of Co- Cr films. The increased importance of the substrates and seedlayers lies in the tendency that in Co-Cr thin film production for recording applications the

  3. Properties of a new magnetic material: Sr2FeMoO6

    Indian Academy of Sciences (India)

    Unknown

    application of a magnetic field, known as Colossal Magnetoresistance (CMR), there has been tremendous increase .... 2.2 Effect of Fe/Mo mis-site disorder on magnetocresistance. We have synthesized highly .... band structure calculations have been carried out 18, using supercells to simulate mis- site disorder between Fe ...

  4. Structural and magnetic properties of the nanocomposite materials based on a mesoporous silicon dioxide matrix

    Energy Technology Data Exchange (ETDEWEB)

    Grigor’eva, N. A., E-mail: natali@lns.pnpi.spb.ru [St. Petersburg State University (Russian Federation); Eckerlebe, H. [Helmholtz-Zentrum Geesthacht (Germany); Eliseev, A. A.; Lukashin, A. V.; Napol’skii, K. S. [Moscow State University (Russian Federation); Kraje, M. [Reactor Institute Delft (Netherlands); Grigor’ev, S. V. [St. Petersburg State University (Russian Federation)

    2017-03-15

    The structural and magnetic properties of the mesoporous systems based on silicon dioxide with a regular hexagonal arrangement of pores several microns in length and several nanometers in diameter, which are filled with iron compound nanofilaments in various chemical states, are studied in detail. The studies are performed using the following mutually complementary methods: transmission electron microscopy, SQUID magnetometry, electron spin resonance, Mössbauer spectroscopy, polarized neutron small-angle diffraction, and synchrotron radiation diffraction. It is shown that the iron nanoparticles in pores are mainly in the γ phase of Fe{sub 2}O{sub 3} with a small addition of the α phase and atomic iron clusters. The effective magnetic field acting on a nanofilament from other nanofilaments is 11 mT and has a dipole nature, the ferromagnetic–paramagnetic transition temperature is in the range 76–94 K depending on the annealing temperature of the samples, and the temperature that corresponds to the change in the magnetic state of the iron oxide nanofilaments is T ≈ 50–60 K at H = 0 and T ≈ 80 K at H = 300 mT. It is also shown that the magnetization reversal of an array of nanofilaments is caused by the magnetostatic interaction between nanofilaments at the fields that are lower than the saturation field.

  5. INTERPRETATION OF MOSSBAUER SPECTRA OF PARAMAGNETIC MATERIALS IN A MAGNETIC FIELD

    NARCIS (Netherlands)

    van der Woude, F.; Dekker, A. J.

    1965-01-01

    A formula is discussed for the hfs of Mossbauer spectra applicable also to situations in which the magnetic field at the nucleus fluctuates with a frequency comparable to the nuclear precession frequency. This formula can explain e.g. the essential features of recent experimental data on hydrated

  6. Correcting and coating thin walled X-ray Optics via a combination of controlled film deposition and magnetic smart materials

    Science.gov (United States)

    Ulmer, Melville

    The project goal is to demonstrate that thin walled (price. Since the desired surface area for the next generation X-ray telescope is >10x that of Chandra, the >10x requirement is then for >200 m^2 of surface area with a surface finish of better than 0.5 nm. Therefore, replication of some sort is called for. Because no replication technology has been shown to achieve ≤1" angular resolution, post fabrication figure corrections are likely going to be necessary. Some have proposed to do this in orbit and others prelaunch including us. Our prelaunch approach is to apply in-plane stresses to the thin walled mirror shells via a magnetic field. The field will be held in by some magnetically hard material such as NiCo. By use of a so called magnetic smart material (MSM) such as Terfenol-D, we already shown that strong enough stresses can be generated. Preliminary work has also shown that the magnetic field can be held in well enough to apply the figure correcting stresses pre-launch. What we call "set-it and forget-it." However, what is unique about our approach is that at the cost of complexity and some areal coverage, our concept will also accommodate in-orbit adjustments. Furthermore, to the best of our knowledge ours is one of two known stress modification processes that are bi-axial. Our plan is first to validate set-it and forget-it first on cantilevers and then to expand this to working on 5 cm x 5 cm pieces. We will work both with NiCo and glass or Si coated with Terfenol-D. Except for the NiCo, substrates we will also coat the samples with NiCo in order to have a film that will hold in the magnetic field. As part of the coating process, we will control the stress of the film by varying the voltage bias while coating. The bias stress control can be used to apply films with minimal stress such as Terfenol-D and X-ray reflecting coatings such as Ir. Ir is a highly desirable coating for soft X-ray astronomy mirrors that can have significant built in stress unless

  7. Curie Temperature and Microstructural Changes Due to the Heating Treatment of Magnetic Amorphous Materials

    Directory of Open Access Journals (Sweden)

    Gondro J.

    2016-03-01

    Full Text Available Three distinct alloys: Fe86Zr7Nb1Cu1B5, Fe82Zr7Nb2Cu1B8, and Fe81Pt5Zr7Nb1Cu1B5 were characterized both magnetically and structurally. The samples, obtained with spinning roller method as a ribbons 3 mm in width and 20 μm thick, were investigated as-quenched and after each step of a multi steps heating treatment procedure. Each sample was annealed at four steps, fifteen minutes at every temperature, starting from 573K+600K up to +700K depending on type of alloy. Mössbauer spectroscopy data and transmission electron microscope (HRE M pictures confirmed that the as-quenched samples are fully amorphous. This is not changed after the first stages of treatment heating leads to a reduction of free volumes. The heating treatment has a great influence on the magnetic susceptibilities. The treatment up to 600K improves soft magnetic properties: an χ increase was observed, from about 400 to almost 1000 for the samples of alloys without Pt, and from about 200 to 450 at maximum, for the Fe81Pt5Zr7Nb1Cu1B5. Further heating, at more elevated temperatures, leads to magnetic hardening of the samples. Curie temperatures, established from the location of Hopkinson’s maxima on the χ(T curve are in very good agreement with those obtained from the data of specific magnetization, σ(T, measured in a field of 0.75T. As a critical parameter β was chosen to be equal 0.36 for these calculations, it confirmed that the alloys may be considered as ferromagnetic of Heisenberg type. Heating treatment resulted in decreasing of TC. These changes are within a range of several K.

  8. ZERO-FIELD NUCLEAR MAGNETIC RESONANCE FOR STUDY OF ANTIFERROMAGNETIC PROPERTIES OF FeF3 MATERIALS

    Directory of Open Access Journals (Sweden)

    G. R. F. Suwandi

    2016-01-01

    Full Text Available Nuclear Magnetic Resonance (NMR has been used as a research tool in many fields. In this study, the magnetic properties, especially anti-ferromagnetic properties of FeF3 materials were investigated. Zero-field custom-built NMR method was used to investigate the anti-ferromagnetic properties in the materials. Experiments have been carried out by varying the sample temperatures from 8 K to 220 K. Ordinary spin echo pulse sequence 90⁰RF–τ–180⁰RF were used. Using Fast Fourier Transform, the signals in NMR spectrum were analyzed and the peak showed the resonance frequency. The result showed that resonance frequencies decrease with increasing in temperature. The frequency of the spectrum was around 85.41 MHz in the zero-temperature limit, and this corresponds with Fe hyperfine field at zero-temperature limit was 2.14 T. The temperature dependence of the local magnetization does not fit T2 Bloch’s Law very well. Instead, it fits the exponential form having an energy gap in the dispersion relation of the spin wave. It is obtained from the result that FeF3 is antiferromagnetic materials with energy gap of 11.466 meV and anisotropy energy of 1.045 meV.Nuclear Magnetic Resonance (NMR telah banyak digunakan sebagai “research tool” pada berbagai bidang kajian di fisika. Pada studi ini, akan dilakukan eksperimen untuk menguji sifat magnetik, khususnya antiferromagnetik pada material FeF3. Telah dilakukan eksperimen dengan memvariasikan temperatur pada sampel dari 8 K hingga 220 K. Pulse sequence yang digunakan adalah 90⁰RF–τ–180⁰RF. Dengan memanfaatkan Fast Fourier Transform, sinyal echo ini dapat dianalisis dalam bentuk spektrum NMR dengan puncak spektrum menunjukkan frekuensi resonansinya. Diperoleh bahwa frekuensi resonansi akan menurun seiring dengan kenaikan temperatur. Posisi frekuensi pada temperatur 0 K adalah sebesar 85,41 MHz, hal ini memperlihatkan bahwa medan hyperfine dari Fe sebesar 2,14 T pada temperatur 0 K. Kurva

  9. Magnetic dendritic materials for highly efficient adsorption of dyes and drugs.

    Science.gov (United States)

    Zhou, Li; Gao, Chao; Xu, Weijian

    2010-05-01

    A versatile and robust adsorbent with both magnetic property and very high adsorption capacity is presented on the basis of functionalization of iron oxide-silica magnetic particles with carboxylic hyperbranched polyglycerol (Fe(3)O(4)/SiO(2)/HPG-COOH). The structure of the resulting product was confirmed by Fourier transform infrared (FTIR) spectra, thermo gravimetric analysis (TGA), zeta-potential, and transmission electron microscopy (TEM). According to the TGA results, the density of the carboxylic groups on the surface of Fe(3)O(4)/SiO(2)/HPG-COOH is calculated to be as high as 3.0 mmol/g, posing a powerful base for adsorbing dyes and drugs. Five kinds of dyes and one representative anticancer drug were chosen to investigate the adsorption capacity of the as-prepared magnetic adsorbent. The adsorbent shows highly efficient adsorption performance for all of the adsorbates especially for the cationic dyes and drug. For example, the saturated adsorption capacity of the Fe(3)O(4)/SiO(2)/HPG-COOH for methyl violet (MV) can reach 0.60 mmol/g, which is much higher than the previous magnetic adsorbents (usually lower than 0.30 mmol/g). 95% of MV and 90% of R6G could be adsorbed within 5 min, and both of the adsorptions reached equilibrium in about 15 min. The adsorption kinetics and isotherm of the adsorbents were investigated in detail and found that the kinetic and equilibrium adsorptions are well-modeled using pseudo-second-order kinetics and Langmuir isotherm model, respectively. In addition, the influences of pH and ionic strength on the adsorption capacity were also examined and found that pH has much greater effect on the adsorption capacity compared with the ionic strength. Regeneration experiments showed that the Fe(3)O(4)/SiO(2)/HPG-COOH can be well-regenerated in ethanol and partially regenerated in 1 M HCl aqueous solution. After regeneration, the magnetic adsorbents can still show high adsorption capacity even for 10 cycles of desorption-adsorption. No

  10. Reduced Dimensionality tailored HN(C)N Pulse Sequences for Efficient Backbone Resonance Assignment of Proteins through Rapid Identification of Sequential HSQC peaks

    CERN Document Server

    Kumar, Dinesh

    2013-01-01

    Two novel reduced dimensionality (RD) experiments -(4,3)D-hNCOcaNH and (4,3)D-hNcoCANH- have been presented here to facilitate the backbone resonance assignment of proteins both in terms of its accuracy and speed. The experiments basically represent an improvisation of previously reported HN(C)N experiment [Panchal et. al., J. Biomol. NMR. (2002), 20 (2), 135-147] and exploit the simple reduced dimensionality NMR concept [Szyperski et. al. (2002), Proc. Natl. Acad. Sci. U.S.A. 99(12), 8009-8014] to achieve (a) higher dispersion and resolution along the co-evolved F1 dimension and (b) rapid identification of sequential HSQC peaks on its F2(15N)- F3(1H) planes. The current implementation is based on the fact that the linear combination of 15N and 13CO/13Ca chemical shifts offers relatively better dispersion and randomness compared to the individual chemical shifts; thus enables the assignment of crowded HSQC spectra by resolving the ambiguities generally encountered in HNCN based assignment protocol because of ...

  11. Materials Characterization of Feraheme/Ferumoxytol and Preliminary Evaluation of Its Potential for Magnetic Fluid Hyperthermia

    Directory of Open Access Journals (Sweden)

    Jon Dobson

    2013-08-01

    Full Text Available Feraheme, is a recently FDA-cleared superparamagnetic iron oxide nanoparticle (SPION-based MRI contrast agent that is also employed in the treatment of iron deficiency anemia. Feraheme nanoparticles have a hydrodynamic diameter of 30 nm and consist of iron oxide crystallites complexed with a low molecular weight, semi-synthetic carbohydrate. These features are attractive for other potential biomedical applications such as magnetic fluid hyperthermia (MFH, since the carboxylated polymer coating affords functionalization of the particle surface and the size allows for accumulation in highly vascularized tumors via the enhanced permeability and retention effect. This work presents morphological and magnetic characterization of Feraheme by transmission electron microscopy (TEM, Energy dispersive X-ray spectroscopy (EDX, and superconducting quantum interference device (SQUID magnetometry. Additionally, the results of an initial evaluation of the suitability of Feraheme for MFH applications are described, and the data indicate the particles possess promising properties for this application.

  12. Scalar-Interchange Potential and Magnetic/Thermodynamic Properties of Graphene-like Materials

    CERN Document Server

    Helayël-Neto, José Abdalla; Martins, Ricardo Spagnuolo

    2016-01-01

    By means of numerical simulations, we explore possible effects of a special interparticle interaction potential which is a function of external and internal conditions of graphene-like systems. In addition to the electromagnetic interaction, we introduce a new potential due to the exchange of a massive scalar, associated to the so-called Kekul\\'e deformations; this interaction displays a spin-dependent profile. It turns out that the magnitude of Kekul\\'e deformation may significantly affect physical properties of graphene. A Monte Carlo analysis enables one to analyze the behavior of the system under variation of the applied external field, temperature, and the particular type of the exchanged excitation that induces the potential. We pursue an investigation of the spin configurations, we analyze differences in thermal equilibrium magnetization and we carry out calculations of the magnetic susceptibility and the specific heat in the presence of the Kekul\\'e-induced new potential.

  13. MAGNET

    CERN Multimedia

    B. Curé

    The first phase of the commissioning ended in August by a triggered fast dump at 3T. All parameters were nominal, and the temperature recovery down to 4.5K was carried out in two days by the cryogenics. In September, series of ramps were achieved up to 3 and finally 3.8T, while checking thoroughly the detectors in the forward region, measuring any movement of and around the HF. After the incident of the LHC accelerator on September 19th, corrective actions could be undertaken in the forward region. When all these displacements were fully characterized and repetitive, with no sign of increments in displacement at each field ramp, it was possible to start the CRAFT, Cosmic Run at Four Tesla (which was in fact at 3.8T). The magnet was ramped up to 18.16kA and the 3 week run went smoothly, with only 4 interruptions: due to the VIP visits on 21st October during the LHC inauguration day; a water leak on the cooling demineralized water circuit, about 1 l/min, that triggered a stop of the cooling pumps, and resulte...

  14. MAGNET

    CERN Multimedia

    Benoit Curé

    The cooling down to the nominal temperature of 4.5 K was achieved at the beginning of August, in conjunction with the completion of the installation work of the connection between the power lines and the coil current leads. The temperature gradient on the first exchanger of the cold box is now kept within the nominal range. A leak of lubricant on a gasket of the helium compressor station installed at the surface was observed and several corrective actions were necessary to bring the situation back to normal. The compressor had to be refilled with lubricant and a regeneration of the filters and adsorbers was necessary. The coil cool down was resumed successfully, and the cryogenics is running since then with all parameters being nominal. Preliminary tests of the 20kA coil power supply were done earlier at full current through the discharge lines into the dump resistors, and with the powering busbars from USC5 to UXC5 without the magnet connected. On Monday evening August 25th, at 8pm, the final commissionin...

  15. MAGNET

    CERN Multimedia

    Benoit Curé

    2013-01-01

    Maintenance work and consolidation activities on the magnet cryogenics and its power distribution are progressing according to the schedules. The manufacturing of the two new helium compressor frame units has started. The frame units support the valves, all the sensors and the compressors with their motors. This activity is subcontracted. The final installation and the commissioning at CERN are scheduled for March–April 2014. The overhauls of existing cryogenics equipment (compressors, motors) are in progress. The reassembly of the components shall start in early 2014. The helium drier, to be installed on the high-pressure helium piping, has been ordered and will be delivered in the first trimester of 2014. The power distribution for the helium compressors in SH5 on the 3.3kV network is progressing. The 3.3kV switches, between each compressor and its hot spare compressor, are being installed, together with the power cables for the new compressors. The 3.3kV electrical switchboards in SE5 will ...

  16. Superconductive material and magnetic field for damping and levitation support and damping of cryogenic instruments

    Science.gov (United States)

    Dolgin, Benjamin P. (Inventor)

    1994-01-01

    A superconductive load bearing support without a mechanical contact and vibration damping for cryogenic instruments in space is presented. The levitation support and vibration damping is accomplished by the use of superconducting magnets and the 'Meissner' effect. The assembly allows for transfer of vibration energy away from the cryogenic instrument which then can be damped by the use of either an electronic circuit or conventional vibration damping mean.

  17. MnFe 2 O 4 /bentonite nano composite as a novel magnetic material ...

    African Journals Online (AJOL)

    It is also found that the presence of bentonite in the magnetic composite has not made any changes in the spinel structure of MnFe2O4. SEM images of the sorbent shows nanocomposite with a uniform structure and nanochannels from 0.3 to 0.8 mμ in diameter having a surface area of 130 m2 g-1. The results also revealed ...

  18. Microwave Magnetic Materials for Radar and Signal Processing Devices - Thin Film and Bulk Oxides and Metals

    Science.gov (United States)

    2007-11-29

    nonlinear ferromagnetic resonance (NLFMR) ter WM =AolylM, expresses the saturation magnetization in a thin film under cw microwave excitation in a CPW of the...2006 to August 3, 2007, there were numerous accomplishments. Seven archival papers were published on (I) ferromagnetic resonance (FMR) measurements in...Permalloy films with an emphasis on the comparison of measurement methods, (2) FMR resonance saturation and Suhl instability processes in Permalloy

  19. Containerless melting and crystallization of diamagnetic organic materials under magnetic levitation condition

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, K; Mogi, I; Awaji, S; Motokawa, M; Watanabe, K [High Field Laboratory for Superconducting Materials, Institute of Materials Research, Tohoku University, Sendai, 980-8577 (Japan)

    2006-11-15

    Containerless crystallization of benzophenone and containerless melting of a cycloolefin polymer were performed under magnetic levitation conditions. It was found that the growth mechanism changes from dendritic growth to facet growth with decreasing the supercooling degree in the crystallization of benzophenone. In the case of containerless melting and solidification of a cycloolefin polymer, spherical samples were obtained by a homogeneous heating in an electric furnace with a heatproof bore scope.

  20. Using Ferromagnetic Material to Extend and Shield the Magnetic Field of a Coil

    Science.gov (United States)

    2017-06-14

    extend the magnetic field generated by a coil along its axial direction while simultaneously shielding (or reducing) the field in the lateral direction by...the edges of the coil, while simultaneously shielding (or reducing) the field in the lateral direction by the application of ferromagnetic cladding...length much greater than the cross- sectional dimensions. Both had cross sections of 2.5 × 5.0 cm. The fields were determined along the line extending

  1. Applications of magnetic surface imprinted materials for solid phase extraction of levofloxacin in serum samples.

    Science.gov (United States)

    Xiao, Deli; Wang, Cuixia; Dai, Hao; Peng, Jun; He, Jia; Zhang, Kai; Kong, Sumei; Qiu, Panzi; He, Hua

    2015-05-01

    In this work, molecularly imprinted magnetic carbon nanotubes (MCNTs@MIPs) was prepared with surface imprinting technique for extraction of levofloxacin in serum samples. The preparation of molecularly imprinted polymers (MIPs) used levofloxacin as template, methacrylic acid as functional monomer, and ethylene glycol dimethacrylate as cross-linker, and the magnetic carbon nanotubes (MCNTs) was synthesized by solvothermal method. The prepared polymers not only can be separated and collected easily by an external magnetic, but also exhibited high specific surface area and high selectivity to template molecules. Kinetic adsorption and static adsorption capacity investigations indicated that the synthesized MCNTs@MIPs had excellent recognition towards levofloxacin. Furthermore, magnetic solid phase extraction (MSPE) using the prepared MCNTs@MIPs as sorbent was then investigated, and an efficient sample cleanup was obtained with recoveries ranged from 78.7 ± 4.8 % to 83.4 ± 4.1%. In addition, several parameters, including the pH of samples, the amount of MCNTs@MIPs, the adsorption and desorption times, and the eluent, were investigated to obtain optimal extraction efficiency. Under the optimal extraction conditions, the stability of the polymer was also evaluated, and the average recovery reduced less than 7.6% after 5 cycles. MCNTs@MIPs successfully applied in the preconcentration and determination of levofloxacin in serum sample suggested that the MSPE method based on the novel polymers could be a promising alternative for selective and efficient extraction of trace amounts of pharmaceutical substances in bio-matrix samples. Copyright © 2015 John Wiley & Sons, Ltd.

  2. Applications of High Throughput (Combinatorial) Methodologies to Electronic, Magnetic, Optical, and Energy-Related Materials

    Science.gov (United States)

    2013-06-17

    American Physical Society. FIG. 28. Structural-magnetic-electronic properties of a La1xSrxMnO3 CCS library as a function of x. (a) A concurrent XRD... tandem with TEM to study hydrogenation in Mg-Ni libraries.319 They found that over a broad range of Ni concentrations, a Ni stabilized fcc Mg phase...the order of the diameter of the capil- lary) investigations of the product phases during electro- chemical catalysis , was devised.375 In this

  3. Unmixing Multi-Component Magnetic Mixtures in Geologic Materials Using First Order Reversal Curve Diagrams

    Science.gov (United States)

    Lascu, I.; Harrison, R. J.; Li, Y.; Muraszko, J.; Channell, J. E. T.; Piotrowski, A. M.; Hodell, D. A.; Necula, C.; Panaiotu, C. G.

    2015-12-01

    We have developed a magnetic unmixing method based on principal component analysis (PCA) of first-order reversal curve (FORC) diagrams. PCA provides an objective and robust statistical framework for unmixing, because it represents data variability as a linear combination of a limited number of principal components that are derived purely on the basis of natural variations contained within the dataset. For PCA we have resampled FORC distributions on grids that capture diagnostic signatures of magnetic domain states. Individual FORC diagrams were then recast as linear combinations of end-member (EM) FORC diagrams, located at user-defined positions in PCA space. The EM selection is guided by constraints derived from physical modeling, and is imposed by data scatter. To test our model, we have investigated temporal variations of two EMs in bulk North Atlantic sediment cores collected from the Rockall Trough and the Iberian Continental Margin. Sediments from these sites contain a mixture of magnetosomes and granulometrically distinct detrital magnetite. We have also quantified the spatial variation of three EM components in surficial sediments along the flow path of the North Atlantic Deep Water (NADW). These samples were separated into granulometric fractions, which also assisted in constraining EM definition. The unmixing model reveals systematic variations in EM relative abundance as a function of distance along NADW flow. Finally, we have applied PCA to the combined dataset of Rockall Trough and NADW sediments, which can be recast as a four-EM mixture, providing enhanced discrimination between components. Our method forms the foundation of a general solution to the problem of unmixing multi-component magnetic mixtures, a fundamental task of rock magnetic studies.

  4. New high dielectric constant materials for tailoring the B1+ distribution at high magnetic fields.

    Science.gov (United States)

    Haines, K; Smith, N B; Webb, A G

    2010-04-01

    The spatial distribution of electromagnetic fields within the human body can be tailored using external dielectric materials. Here, we introduce a new material with high dielectric constant, and also low background MRI signal. The material is based upon metal titanates, which can be made into a geometrically-formable suspension in de-ionized water. The material properties of the suspension are characterized from 100 to 400 MHz. Results obtained at 7 T show a significant increase in image intensity in areas such as the temporal lobe and base of the brain with the new material placed around the head, and improved performance compared to purely water-based gels. 2010 Elsevier Inc. All rights reserved.

  5. Direct-write 3D printing of composite materials with magnetically aligned discontinuous reinforcement

    Science.gov (United States)

    Martin, Joshua J.; Caunter, Andrew; Dendulk, Amy; Goodrich, Scott; Pembroke, Ryan; Shores, Dan; Erb, Randall M.

    2017-05-01

    Three-dimensional (3D) printing of fiber reinforced composites represents an enabling technology that may bring toughness and specific strength to complex parts. Recently, direct-write 3D printing has been offered as a promising route to manufacturing fiber reinforced composites that show high specific strength. These approaches primarily rely on the use of shear-alignment during the extrusion process to align fibers along the printing direction. Shear alignment prevents fibers from being oriented along principle stress directions of the final designed part. This paper describes a new direct-write style 3D printing system that incorporates magnetic fields to actively control the orientation of reinforcing fibers during the printing of fiber reinforced composites. Such a manufacturing system is fraught with complications from the high shear dominated alignment experienced by the fibers during extrusion to the slow magnetic alignment dynamics of fibers in viscous media. Here we characterize these issues and suggest effective operating windows in which magnetic alignment is a viable approach to orienting reinforcing particles during direct-write 3D printing.

  6. Artifacts in magnetic resonance imaging and computed tomography caused by dental materials.

    Directory of Open Access Journals (Sweden)

    Thomas Klinke

    Full Text Available BACKGROUND: Artifacts caused by dental restorations, such as dental crowns, dental fillings and orthodontic appliances, are a common problem in MRI and CT scans of the head and neck. The aim of this in-vitro study was to identify and evaluate the artifacts produced by different dental restoration materials in CT and MRI images. METHODS: Test samples of 44 materials (Metal and Non-Metal commonly used in dental restorations were fabricated and embedded with reference specimens in gelatin moulds. MRI imaging of 1.5T and CT scan were performed on the samples and evaluated in two dimensions. Artifact size and distortions were measured using a digital image analysis software. RESULTS: In MRI, 13 out of 44 materials produced artifacts, while in CT 41 out of 44 materials showed artifacts. Artifacts produced in both MRI and CT images were categorized according to the size of the artifact. SIGNIFICANCE: Metal based restoration materials had strong influence on CT and less artifacts in MRI images. Rare earth elements such as Ytterbium trifluoride found in composites caused artifacts in both MRI and CT. Recognizing these findings would help dental materials manufacturers and developers to produce materials which can cause less artifacts in MRI and CT images.

  7. Hypothesis-driven classification of materials using nuclear magnetic resonance relaxometry

    Science.gov (United States)

    Espy, Michelle A.; Matlashov, Andrei N.; Schultz, Larry J.; Volegov, Petr L.

    2016-08-09

    Technologies related to identification of a substance in an optimized manner are provided. A reference group of known materials is identified. Each known material has known values for several classification parameters. The classification parameters comprise at least one of T.sub.1, T.sub.2, T.sub.1.rho., a relative nuclear susceptibility (RNS) of the substance, and an x-ray linear attenuation coefficient (LAC) of the substance. A measurement sequence is optimized based on at least one of a measurement cost of each of the classification parameters and an initial probability of each of the known materials in the reference group.

  8. Self-Assembly-Directed Aerogel and Membrane Formation from a Magnetic Composite: An Approach to Developing Multifunctional Materials.

    Science.gov (United States)

    Vivek, Balachandran; Prasad, Edamana

    2017-03-01

    Herein, we report the preparation of an aerogel and a membrane from a magnetic composite material by tuning the self-assembly at the molecular level. The gel exhibits an excellent oil absorption property, and the membrane shows a remarkable autonomous self-healing property. The composite is formed from an organosilicon-modified poly(amidoamine) (PAMAM) dendrimer, which is linked with iron oxide nanoparticles and poly(vinyl alcohol). Upon the addition of a cross-linker (formaldehyde), the system undergoes a fast self-assembly and gelation process. The aerogel, obtained after drying of the hydrogel, was modified with 1- bromohexadecane at room temperature and utilized for the removal of oil from water with 22.9 g/g absorption capacity. Intriguingly, the same system forms a membrane with 97% autonomous self-healing ability, in the absence of the cross-linker. The membrane was used to remove the salt content from water with an efficiency of 85%. The control experiments suggest that the presence of the magnetic material (iron oxide) plays a key role in the formation of both the aerogel and membrane.

  9. P(3HB) based magnetic nanocomposites: smart materials for bone tissue engineering

    Czech Academy of Sciences Publication Activity Database

    Akaraonye, E.; Filip, J.; Šafaříková, Miroslava; Salih, V.; Keshavarz, T.; Knowles, J.C.; Roy, I.

    -, č. 2016 (2016), č. článku 3897592. ISSN 1687-4110 Institutional support: RVO:60077344 Keywords : composite films * dispersions * elastic moduli * intelligent materials * nanocomposites Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.871, year: 2016

  10. Research on materials for advanced electronic and aerospace application. [including optical and magnetic data processing, stress corrosion and H2 interaction, and polymeric systems

    Science.gov (United States)

    1975-01-01

    Development and understanding of materials most suitable for use in compact magnetic and optical memory systems are discussed. Suppression of metal deterioration by hydrogen is studied. Improvement of mechanical properties of polymers is considered, emphasizing low temperature ductility and compatibility with high modulus fiber materials.

  11. Cognition of the Metallic Material Properties and Physical Dimensions by Magnetic Sensor Signal Visualization

    Science.gov (United States)

    Saito, Yoshifuru; Marinova, Iliana; Endo, Hisashi

    This paper proposes a method of 3-D Lissajous diagram for signal processing of a differential coil type magnetic sensor. Overlapping several Lissajous diagrams between the sensor input and output signals yields a three-dimension or grayscale image whose height or tone reveals a number of overlapped points. This conversion from the time-domain sensor signals to an image provides the differences in frequency, amplitude, phase, distortion, etc. Employing image cognition methodology to this three-dimension image makes it possible to identify each of the signals stored in a database. We demonstrate the renmarkable cognition results by our magnetc sensor signals processing strategy.

  12. Magnetic Properties of Antiferromagnetic Oxide Materials Surfaces, Interfaces, and Thin Films

    CERN Document Server

    Duò, Lamberto; Ciccacci, Franco

    2010-01-01

    This first focused treatment on a hot topic highlights fundamental aspects as well as technological applications arising from a fascinating area of condensed matter physics. The editors have excellent track records and, in light of the broadness of the topic, retain the focus on antiferromagnetic oxides. They thus cover such topics as dichroism in x-ray absorption, non-magnetic substrates, exchange bias, ferromagnetic-antiferromagnetic interface coupling and oxide multilayers, as well as imaging using soft x-ray microscopy. The result is a very timely monograph for solid state physicists and c

  13. Experimental studies of materials migration in magnetic confinement fusion devices : Novel methods for measurement of macro particle migration, transport of atomic impurities and characterization of exposed surfaces

    OpenAIRE

    Bykov, Igor

    2014-01-01

    During several decades of research and development in the field of Magnetically Confined Fusion (MCF) the preferred selection of materials for Plasma Facing Components (PFC) has changed repeatedly. Without doubt, endurance of the first wall will decide research availability and lifespan of the first International Thermonuclear Research Reactor (ITER). Materials erosion, redeposition and mixing in the reactor are the critical processes responsible for modification of materials properties under...

  14. Effect of substitutional defects on Kambersky damping in L1{sub 0} magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Qu, T. [School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Victora, R. H., E-mail: victora@umn.edu [School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

    2015-02-16

    Kambersky damping, representing the loss of magnetic energy from the electrons to the lattice through the spin orbit interaction, is calculated for L1{sub 0} FePt, FePd, CoPt, and CoPd alloys versus chemical degree of order. When more substitutional defects exist in the alloys, damping is predicted to increase due to the increase of the spin-flip channels allowed by the broken symmetry. It is demonstrated that this corresponds to an enhanced density of states (DOS) at the Fermi level, owing to the rounding of the DOS with loss of long-range order. Both the damping and the DOS of the Co-based alloy are found to be less affected by the disorder. Pd-based alloys are predicted to have lower damping than Pt-based alloys, making them more suitable for high density spintronic applications.

  15. Hysteresis Modelling of Soft Magnetic Materials using LabVIEW Programs

    Directory of Open Access Journals (Sweden)

    SCUTARU, G.

    2010-05-01

    Full Text Available The paper deals with an analytical model for hysteresis cycle representation. The hysteresis curve is decomposed in a series of arcs of circles and segments of lines. Each arc of circle or segment of line is expressed using analytical geometry as a function of some given parameters or calculated ones. The easiness of the model proposed is given by the small amount of input data needed to represent the hysteresis cycle in a satisfactory way. Using an inverse mapping function from major hysteresis branches the minor cycles, reversal curve of the first kind or curve of first magnetization can be obtained. Finally a comparison between the measured data and modelled ones was made.

  16. Qualification of a Material and a Process for Insulating the LHC Magnet Instrumentation Wiring

    CERN Document Server

    Brun, G

    2000-01-01

    The tests described in this note follow an initial series made on various types of instrumentation wiring as described in the LHC project notes 46 and 57. [1]-[2] One limit to the insulation tests in liquid helium was caused by the presence of gaseous helium in part of the experimental set-up, which gave rise to breakdowns which could not be ascribed with certainty to the sample being tested but were more likely to be caused by the contiguous sample sections in the gas. A new set of measurements was therefore made with a more appropriate cryogenic test set-up. In addition, in order to make the best possible allowance for the conditions in which these wires are in the LHC magnets, tests were also made on irradiated samples and in gaseous helium; the latter check was necessitated by the choice of the feed-through tube which takes the wires from the cold masses to the normal environment.

  17. Revealing the interparticle magnetic interactions of iron oxide nanoparticles-carbon nanotubes hybrid materials

    NARCIS (Netherlands)

    Douvalis, A.P.; Georgakilas, V.; Tsoufis, T.; Gournis, D.; Kooi, B.; Bakas, T.

    2010-01-01

    Spinel iron oxide nanoparticles capped with organic molecules have been successfully prepared and used to produce iron oxide nanoparticles-single wall carbon nanotubes hybrid materials, which were characterized by a number of experimental techniques. The nanoparticles in both samples have an average

  18. Preparation of Core-Shell Hybrid Materials by Producing a Protein Corona Around Magnetic Nanoparticles.

    Science.gov (United States)

    Weidner, A; Gräfe, C; von der Lühe, M; Remmer, H; Clement, J H; Eberbeck, D; Ludwig, F; Müller, R; Schacher, F H; Dutz, S

    2015-12-01

    Nanoparticles experience increasing interest for a variety of medical and pharmaceutical applications. When exposing nanomaterials, e.g., magnetic iron oxide nanoparticles (MNP), to human blood, a protein corona consisting of various components is formed immediately. The composition of the corona as well as its amount bound to the particle surface is dependent on different factors, e.g., particle size and surface charge. The actual composition of the formed protein corona might be of major importance for cellular uptake of magnetic nanoparticles. The aim of the present study was to analyze the formation of the protein corona during in vitro serum incubation in dependency of incubation time and temperature. For this, MNP with different shells were incubated in fetal calf serum (FCS, serving as protein source) within a water bath for a defined time and at a defined temperature. Before and after incubation the particles were characterized by a variety of methods. It was found that immediately (seconds) after contact of MNP and FCS, a protein corona is formed on the surface of MNP. This formation led to an increase of particle size and a slight agglomeration of the particles, which was relatively constant during the first minutes of incubation. A longer incubation (from hours to days) resulted in a stronger agglomeration of the FCS incubated MNP. Quantitative analysis (gel electrophoresis) of serum-incubated particles revealed a relatively constant amount of bound proteins during the first minutes of serum incubation. After a longer incubation (>20 min), a considerably higher amount of surface proteins was determined for incubation temperatures below 40 °C. For incubation temperatures above 50 °C, the influence of time was less significant which might be attributed to denaturation of proteins during incubation. Overall, analysis of the molecular weight distribution of proteins found in the corona revealed a clear influence of incubation time and temperature on

  19. Preparation of Core-Shell Hybrid Materials by Producing a Protein Corona Around Magnetic Nanoparticles

    Science.gov (United States)

    Weidner, A.; Gräfe, C.; von der Lühe, M.; Remmer, H.; Clement, J. H.; Eberbeck, D.; Ludwig, F.; Müller, R.; Schacher, F. H.; Dutz, S.

    2015-07-01

    Nanoparticles experience increasing interest for a variety of medical and pharmaceutical applications. When exposing nanomaterials, e.g., magnetic iron oxide nanoparticles (MNP), to human blood, a protein corona consisting of various components is formed immediately. The composition of the corona as well as its amount bound to the particle surface is dependent on different factors, e.g., particle size and surface charge. The actual composition of the formed protein corona might be of major importance for cellular uptake of magnetic nanoparticles. The aim of the present study was to analyze the formation of the protein corona during in vitro serum incubation in dependency of incubation time and temperature. For this, MNP with different shells were incubated in fetal calf serum (FCS, serving as protein source) within a water bath for a defined time and at a defined temperature. Before and after incubation the particles were characterized by a variety of methods. It was found that immediately (seconds) after contact of MNP and FCS, a protein corona is formed on the surface of MNP. This formation led to an increase of particle size and a slight agglomeration of the particles, which was relatively constant during the first minutes of incubation. A longer incubation (from hours to days) resulted in a stronger agglomeration of the FCS incubated MNP. Quantitative analysis (gel electrophoresis) of serum-incubated particles revealed a relatively constant amount of bound proteins during the first minutes of serum incubation. After a longer incubation (>20 min), a considerably higher amount of surface proteins was determined for incubation temperatures below 40 °C. For incubation temperatures above 50 °C, the influence of time was less significant which might be attributed to denaturation of proteins during incubation. Overall, analysis of the molecular weight distribution of proteins found in the corona revealed a clear influence of incubation time and temperature on corona

  20. Study on the characteristics of magnetic levitation for permanent magnets and ferromagnetic materials with various sizes using stacked HTS bulk annuli

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S.B., E-mail: kim@elec.okayama-u.ac.jp [Graduate School of Natural Science and Technology, Okayama University, 3-1-1, Tsushima-Naka, Kita-ku, Okayama 700-8530 (Japan); Matsunaga, J.; Doi, A.; Ikegami, T. [Graduate School of Natural Science and Technology, Okayama University, 3-1-1, Tsushima-Naka, Kita-ku, Okayama 700-8530 (Japan); Onodera, H. [JST-CREST, K’s Gobancho 6F, 7 Gobancho, Chiyoda-ku, Tokyo 102-0076 (Japan)

    2013-01-15

    Highlights: ► We achieved the stable levitation of irons by magnetized HTS bulk annuli. ► The relationship between magnetized field and sample size was cleared. ► The iron samples smaller than 1 mm diameter could not levitate stably. ► The spherical solenoid magnet was fabricated to levitate small iron samples. -- Abstract: We achieved stable levitation of cylindrical permanent magnets and irons using stacked ring-shaped high temperature superconducting (HTS) bulks with 20 mm ID, 60 mm OD and 50 mm height, and those were magnetized by field cooling method. The levitation characteristics of permanent magnets and iron samples located in the inner space of that levitation system were investigated experimentally. Iron samples with needle-shape and smaller than 1 mm diameter could not levitate stably. However, we found that the high strength of magnetized field was not necessary to levitate small needle-shaped irons. In order to levitate them, we need a uniform magnetic field in radial direction, so, a spherical solenoid magnet that can easily make a homogeneous magnetic field in inner space of HTS bulk annuli was developed. The spherical solenoid magnet, composed of seven solenoid coils with different inner and outer diameters, was designed by an electromagnetic analysis and fabricated.

  1. Octadecylimidazolium ionic liquid-modified magnetic materials: Preparation, adsorption evaluation and their excellent application for honey and cinnamon.

    Science.gov (United States)

    Liu, Houmei; Li, Zhan; Takafuji, Makoto; Ihara, Hirotaka; Qiu, Hongdeng

    2017-08-15

    A novel and versatile adsorbent based on 1-octadecylimidazolium ionic liquid modified magnetic nanoparticles (Fe3O4@SiO2@ImC18) possessing of both magnetic property and excellent adsorption ability was successfully synthesized. Twelve compounds from four kinds of substances (alkylbenzenes, PAHs, flavonoids and organic acids) were chosen as probe molecules to evaluate adsorption properties of the new adsorbent. A series of adsorption experiments were conducted and results indicated both synergism and competition effects were existed and multiple interactions took place during adsorption process. After considerable acquaintances with the adsorbent, it was successfully applied for real samples analysis of honey and cinnamon. Three flavonoid compounds of myricetin, quercetin and luteolin from honey and cinnamic acid from cinnamon were all detected and quantified. Meanwhile, it reached 280-fold concentration reduction of interferent during the extraction of cinnamic acid from cinnamon. The recoveries were in the range of 85.4-94.8% with relative standard deviations (n=3) of 2.5-5.6%.The current study not only provided a strategy to evaluate new adsorbent, but also demonstrated the novel Fe3O4@SiO2@ImC18 material was reliable, accurate and suitable for sample pretreatment in pharmaceutical and food chemistry. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Effect of spacer material on the magnetic surface anisotropy in ultrathin Fe70B30 multilayer films

    Science.gov (United States)

    Hicken, R. J.; Rado, G. T.; Chien, C. L.

    1991-04-01

    It has been found recently that the magnetic surface anisotropy Ks in Fe70B30/Ag multilayer films decreases monotonically with magnetic layer thickness (2L) for 2L<16.5 Å. In order to determine possible effects of the spacer material on the surface anisotropy in the aforementioned system, Ag has been replaced with Al2O3 and ferromagnetic resonance (FMR) measurements have been made on these films. These Fe70B30/Al2O3 films were fabricated by magnetron sputtering and were characterized by x-ray-diffraction and vibrating sample magnetometer (VSM) measurements in addition to FMR. In the region where Ks depends upon 2L, the data is insufficient to confirm the thickness dependence of Ks that was observed in Fe70B30/Ag, while in the region where Ks is independent of 2L, the values of Ks deduced for Fe70B30/Ag and Fe70B30/Al2O3 are in good agreement. The latter is particularly interesting in light of the enormous difference in conductivity between Ag and Al2O3.

  3. Rare earth permanent-magnet alloys’ high temperature phase transformation in situ and dynamic observation and its application in material design

    CERN Document Server

    Pan, Shuming

    2013-01-01

    The process of high temperature phase transition of rare earth permanent-magnet alloys is revealed by photographs taken by high voltage TEM. The relationship between the formation of nanocrystal and magnetic properties is discussed in detail, which effects alloys composition and preparation process. The experiment results verified some presumptions, and were valuable for subsequent scientific research and creating new permanent-magnet alloys. The publication is intended for researchers, engineers and managers in the field of material science, metallurgy, and physics. Prof. Shuming Pan is senior engineer of Beijing General Research Institute of Non-ferrous Metal.

  4. Method of making active magnetic refrigerant, colossal magnetostriction and giant magnetoresistive materials based on Gd-Si-Ge alloys

    Science.gov (United States)

    Gschneidner, Jr., Karl A.; Pecharsky, Alexandra O.; Pecharsky, Vitalij K.

    2003-07-08

    Method of making an active magnetic refrigerant represented by Gd.sub.5 (Si.sub.x Ge.sub.1-x).sub.4 alloy for 0.ltoreq.x.ltoreq.1.0 comprising placing amounts of the commercially pure Gd, Si, and Ge charge components in a crucible, heating the charge contents under subambient pressure to a melting temperature of the alloy for a time sufficient to homogenize the alloy and oxidize carbon with oxygen present in the Gd charge component to reduce carbon, rapidly solidifying the alloy in the crucible, and heat treating the solidified alloy at a temperature below the melting temperature for a time effective to homogenize a microstructure of the solidified material, and then cooling sufficiently fast to prevent the eutectoid decomposition and improve magnetocaloric and/or the magnetostrictive and/or the magnetoresistive properties thereof.

  5. Versatile variable temperature and magnetic field scanning probe microscope for advanced material research

    Science.gov (United States)

    Jung, Jin-Oh; Choi, Seokhwan; Lee, Yeonghoon; Kim, Jinwoo; Son, Donghyeon; Lee, Jhinhwan

    2017-10-01

    We have built a variable temperature scanning probe microscope (SPM) that covers 4.6 K-180 K and up to 7 T whose SPM head fits in a 52 mm bore magnet. It features a temperature-controlled sample stage thermally well isolated from the SPM body in good thermal contact with the liquid helium bath. It has a 7-sample-holder storage carousel at liquid helium temperature for systematic studies using multiple samples and field emission targets intended for spin-polarized spectroscopic-imaging scanning tunneling microscopy (STM) study on samples with various compositions and doping conditions. The system is equipped with a UHV sample preparation chamber and mounted on a two-stage vibration isolation system made of a heavy concrete block and a granite table on pneumatic vibration isolators. A quartz resonator (qPlus)-based non-contact atomic force microscope (AFM) sensor is used for simultaneous STM/AFM operation for research on samples with highly insulating properties such as strongly underdoped cuprates and strongly correlated electron systems.

  6. Transmission electron microscopy study of nanostructured Nd-Fe-B hard magnetic materials

    CERN Document Server

    Marashi, S P H

    2001-01-01

    route. Inferior magnetic properties especially for sub j H sub c and (BH) sub m sub a sub x , were observed for over-quenched and annealed alloys compared with those prepared by directly quenching. The Ga addition did however result in some improvement in sub j H sub c and (BH) sub m sub a sub x , especially for the directly quenched alloy containing 1.5 at.% Ga. The microstructure of ribbon samples were studied extensively by TEM and, in addition to normal polygonal Nd sub 2 Fe sub 1 sub 4 B grains, other more unusual morphologies such as spherical and plate like grains, were found in a number of samples. Various grain size distributions were also observed. Texture and the orientation relationship between alpha-Fe precipitates and Nd sub 2 Fe sub 1 sub 4 B matrix were studied in the near stoichiometric sample containing 3 at.% Ga, melt spun at low roll speeds, and an attempt was made to identify additional phases observed in this sample. Some dislocation-type features found in some samples were also studied....

  7. Characterization of proton exchange membrane materials for fuel cells by solid state nuclear magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Zueqian [Iowa State Univ., Ames, IA (United States)

    2010-01-01

    Solid-state nuclear magnetic resonance (NMR) has been used to explore the nanometer-scale structure of Nafion, the widely used fuel cell membrane, and its composites. We have shown that solid-state NMR can characterize chemical structure and composition, domain size and morphology, internuclear distances, molecular dynamics, etc. The newly-developed water channel model of Nafion has been confirmed, and important characteristic length-scales established. Nafion-based organic and inorganic composites with special properties have also been characterized and their structures elucidated. The morphology of Nafion varies with hydration level, and is reflected in the changes in surface-to-volume (S/V) ratio of the polymer obtained by small-angle X-ray scattering (SAXS). The S/V ratios of different Nafion models have been evaluated numerically. It has been found that only the water channel model gives the measured S/V ratios in the normal hydration range of a working fuel cell, while dispersed water molecules and polymer ribbons account for the structures at low and high hydration levels, respectively.

  8. Materialism.

    Science.gov (United States)

    Melnyk, Andrew

    2012-05-01

    Materialism is nearly universally assumed by cognitive scientists. Intuitively, materialism says that a person's mental states are nothing over and above his or her material states, while dualism denies this. Philosophers have introduced concepts (e.g., realization and supervenience) to assist in formulating the theses of materialism and dualism with more precision, and distinguished among importantly different versions of each view (e.g., eliminative materialism, substance dualism, and emergentism). They have also clarified the logic of arguments that use empirical findings to support materialism. Finally, they have devised various objections to materialism, objections that therefore serve also as arguments for dualism. These objections typically center around two features of mental states that materialism has had trouble in accommodating. The first feature is intentionality, the property of representing, or being about, objects, properties, and states of affairs external to the mental states. The second feature is phenomenal consciousness, the property possessed by many mental states of there being something it is like for the subject of the mental state to be in that mental state. WIREs Cogn Sci 2012, 3:281-292. doi: 10.1002/wcs.1174 For further resources related to this article, please visit the WIREs website. Copyright © 2012 John Wiley & Sons, Ltd.

  9. Reduced Dimensionality Lithium Niobate Microsystems

    Energy Technology Data Exchange (ETDEWEB)

    Eichenfield, Matt [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-01-01

    The following report describes work performed under the LDRD program at Sandia National Laboratories October 2014 and September 2016. The work presented demonstrates the ability of Sandia Labs to develop state-of-the-art photonic devices based on thin film lithium niobate (LiNbO3 ). Section 1 provides an introduction to integrated LiNbO3 devices and motivation for developing thin film nonlinear optical systems. Section 2 describes the design, fabrication, and photonic performance of thin film optical microdisks fabricated from bulk LiNbO3 using a bulk implantation method developed at Sandia. Sections 3 and 4 describe the development of similar thin film LiNbO3 structures fabricated from LiNbO3 on insulator (LNOI) substrates and our demonstration of optical frequency conversion with state-of-the-art efficiency. Finally, Section 5 describes similar microdisk resonators fabricated from LNOI wafers with a buried metal layer, in which we demonstrate electro-optic modulation.

  10. Cyclo-biphenalenyl Biradicaloid Molecular Materials: Conformation, Tautomerization, Magnetism, and Thermochromism

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jingsong [ORNL; Meunier, Vincent [ORNL; Tian, Yong-Hui [Georgetown University; Kertesz, Prof. Miklos [Georgetown University

    2010-01-01

    Phenalenyl and its derivatives have recently attracted a great deal of interest as a result of a two-electron multicenter (2e/mc) - bonding between two -stacked phenalenyl units. The 2e/mc bonded -dimers are close in energy to the -dimers of phenalenyl and therefore fickle properties may emerge from bond fluctuation, yielding smart -functional materials. Here, we examine the valence tautomerization of two cyclo-biphenalenyl biradicaloid molecular materials with chair and boat conformations by spin-restricted (R) and unrestricted (U) DFT using the M06 and B3LYP functionals. We found that the chair conformation involves a 2e/4c - bonded structure, whereas the boat conformation involves a 2e/12c - bonded structure on their potential energy surfaces. The global minimum for the chair conformation is the -bonded structure, whereas it is the - bonded structure for the boat conformation. The chair conformation exhibits a stepwise [3,3]-sigmatropic rearrangement, and calculations predict a negligible paramagnetic susceptibility near room temperature. In comparison, the paramagnetism of the boat conformation should be observable by SQUID and ESR. According to the energy differences of the respective - and -dimers of the two conformations and the UV-vis calculations, the color of the chair conformation is expected to become darker, whereas that of the boat conformation should become lighter with increasing temperature.

  11. Haemocompatibility and cytotoxic studies of non-metallic composite materials modified with magnetic nano and microparticles.

    Science.gov (United States)

    Szymonowicz, Maria; Rybak, Zbigniew; Fraczek-Szczypta, Aneta; Paluch, Danuta; Rusak, Agnieszka; Nowicka, Katarzyna; Blazewicz, Marta

    2015-01-01

    Preventing the formation of blood clots on the surface of biomaterials and investigation of the reasons of their formation are the leading topics of the research and development of biomaterials for implants placed into the bloodstream. Biocompatibility and stability of a material in body fluids and direct effect on blood cell counts components are related both to the structure and physico-chemical state of an implant surface. The aim of this study was to determine haemocompatibility and cytotoxicity of polysulfone-based samples containing nano and micro particles of magnetite (Fe3O4). The polysulfone-based samples modified with nanometric and micrometric magnetite particles were examined. Physicochemical properties of the composites were determined by testing their wettability and surface roughness. The action of haemolytic, activation of coagulation system and cytotoxicity of composites was evaluated. Wettability and roughness of materials were correlated with nanoparticles and microparticles content. In the tests of plasma coagulation system shortening of activated partial thromboplastin time for polysulfone with nano magnetite and with micro magnetite particles was observed in comparison with pure polysulfone. Prothrombine time and thrombine time values as well as fibrinogen concentration were unchanged. Haemolysis values were normal. Morphology and viability of cells were normal. Composites made from polysulfone modified with nanoparticles and microparticles of magnetite cause neither haemolytic nor cytotoxic reaction. These composites evoke plasma endogenous system activation.

  12. Cyclo-biphenalenyl biradicaloid molecular materials: conformation, tautomerization, magnetism, and thermochromism

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jingsong [ORNL; Sumpter, Bobby G [ORNL; Meunier, Vincent [ORNL; Tian, Yong-Hui [Georgetown University; Kertesz, Prof. Miklos [Georgetown University

    2011-01-01

    Phenalenyl and its derivatives have recently attracted a great deal of interest as a result of a 2-electron multicenter (2e/mc) covalent pi-pi bonding between two pi-stacked phenalenyl units. The 2e/mc bonded pi-dimers are close in energy to the sigma-dimers of phenalenyl and therefore fickle properties may emerge from bond fluctuation, yielding smart pi-functional materials. Here we examine the valence tautomerization of two cyclo-biphenalenyl biradicaloid molecular materials with chair- and boat-conformations by spin-restricted (R) and unrestricted (U) DFT using the M06 and B3LYP functionals. We found that the chair-conformation involves a 2e/4c pi-pi bonded structure while the boat-conformation involves a 2e/12c pi-pi bonded structure on their potential energy surfaces. The global minimum for the chair-conformation is the sigma-bonded structure while it is the pi-pi bonded structure for the boat-conformation. The chair-conformation exhibits a stepwise [3,3]-sigmatropic rearrangement, and calculations predict a negligible paramagnetic susceptibility near room temperature. In comparison, the paramagnetism of the boat-conformation should be observable by SQUID and/or ESR. According to the difference of the global minima of the two conformations and the parameterized UV-Vis calculations, the color of the chair-conformation is expected to become darker while that of the boat-conformation become lighter with increasing temperature.

  13. A Bayesian approach for the stochastic modeling error reduction of magnetic material identification of an electromagnetic device

    Science.gov (United States)

    Abdallh, A.; Crevecoeur, G.; Dupré, L.

    2012-03-01

    Magnetic material properties of an electromagnetic device can be recovered by solving an inverse problem where measurements are adequately interpreted by a mathematical forward model. The accuracy of these forward models dramatically affects the accuracy of the material properties recovered by the inverse problem. The more accurate the forward model is, the more accurate recovered data are. However, the more accurate ‘fine’ models demand a high computational time and memory storage. Alternatively, less accurate ‘coarse’ models can be used with a demerit of the high expected recovery errors. This paper uses the Bayesian approximation error approach for improving the inverse problem results when coarse models are utilized. The proposed approach adapts the objective function to be minimized with the a priori misfit between fine and coarse forward model responses. In this paper, two different electromagnetic devices, namely a switched reluctance motor and an EI core inductor, are used as case studies. The proposed methodology is validated on both purely numerical and real experimental results. The results show a significant reduction in the recovery error within an acceptable computational time.

  14. Structural, magnetic and electric properties of Nd and Ni co-doped BiFeO3 materials

    Directory of Open Access Journals (Sweden)

    Dao Viet Thang

    2017-09-01

    Full Text Available Multiferroic Bi1−xNdxFe0.975Ni0.025O3 (x = 0.00, 0.05, 0.10, 0.125, and 0.15 (BNFNO and BiFeO3 (BFO materials were synthesized by a sol-gel method. Crystal structure, ferromagnetic and ferroelectric properties of the as-synthesized materials were investigated. Results showed that Nd3+ and Ni2+ co-doping affected to the electrical leakage, enhanced ferroelectric polarization and magnetization of BiFeO3. Co-doped sample with 12.5 mol% of Nd3+ and 2.5 mol% of Ni2+ exhibited an enhancement in both ferromagnetism and ferroelectric properties up to MS ~ 0.528 emu/g and PS ~ 18.35 μC/cm2 with applied electric field at 5 kV/cm, respectively. The origins of ferromagnetism and ferroelectricity enhancement were discussed in the paper.

  15. Classification of materials using nuclear magnetic resonance dispersion and/or x-ray absorption

    Science.gov (United States)

    Espy, Michelle A.; Matlashov, Andrei N.; Schultz, Larry J.; Volegov, Petr L.; Urbaitis, Algis; Sandin, Henrik; Yoder, Jacob; Surko, Stephen

    2017-01-31

    Methods for determining the identity of a substance are provided. A classification parameter set is defined to allow identification of substances that previously could not be identified or to allow identification of substances with a higher degree of confidence. The classification parameter set may include at least one of relative nuclear susceptibility (RNS) or an x-ray linear attenuation coefficient (LAC). RNS represents the density of hydrogen nuclei present in a substance relative to the density of hydrogen nuclei present in water. The extended classification parameter set may include T.sub.1, T.sub.2, and/or T.sub.1.rho. as well as at least one additional classification parameter comprising one of RNS or LAC. Values obtained for additional classification parameters as well as values obtained for T.sub.1, T.sub.2, and T.sub.1.rho. can be compared to known classification parameter values to determine whether a particular substance is a known material.

  16. Non-contact ultrasonic measurements of the elastic constants of magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, R S; Perry, R; Backhouse, D J; Moore, I J; Cleanthous, D; Clough, A R; Stone, D, E-mail: r.s.edwards@warwick.ac.uk [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2011-03-01

    Ultrasonic testing using contacting transducers such as quartz or PZT is well established. However, standard measurement techniques used require physical contact of the sample and ultrasonic transducer and some sort of couplant between the two. With this configuration there is a possibility of damaging the sample, transducer or bond during testing, thermal cycling, or removal of the transducer. We present results taken using recent advances in non-contact methods of ultrasound generation and detection using electromagnetic acoustic transducers (EMATs), which offer some significant benefits over contact ultrasonic techniques. Circumventing the need for couplant removes the possibility of contaminating the system, which is an issue for some material property measurements, and allows easier measurements over a wider range of temperatures. An automated data analysis system has been developed which allows the velocity of sound in the sample, and hence the elastic constants, to be determined to a high accuracy. This technique is illustrated using measurements of the alloy Gd{sub 64}Sc{sub 36}.

  17. Effects of surface states, defects and dopants on the optical and magnetic properties of low-dimensional materials

    Science.gov (United States)

    Podila, Ramakrishna

    Nanomaterials have attracted the attention of researchers from various fields due to their unique features (that are otherwise absent in the bulk) such as quantum confinement, high surface to volume ratio, ability for surface modification etc. Since the discovery of fullerenes and carbon nanotubes, several synthesis techniques have been developed for nanomaterial growth. However, different control parameters in different synthesis techniques often result in nanostructures with varying defects that may alter their fundamental behavior. Such defects or disorder in the crystal lattice can lead to the disruption of lattice symmetry. The defect-induced symmetry lowering (or breaking) effects play a vital role in the determination of fundamental material characteristics. Thus, it is very important to characterize the defects in order to understand their effects on the nanomaterial properties. This thesis describes the effects of defects in low dimesional systems such as ZnO nanowires, graphene and carbon nanotubes are studied. Firstly, it describes the synthesis and characterization of ZnO nanostructures and discusses the effects of surface states, defects and dopants on their optical and magnetic properties. An unexpected presence of ferromagnetic (FM) ordering in nanostructured nonmagnetic metal oxides has been reported previously. Though this property was attributed to the presence of defects, systematic experimental and theoretical studies to pinpoint its origin and mechanism were lacking. While it is widely believed that oxygen vacancies are responsible for FM ordering, surprisingly annealing as-prepared samples at low temperature (high temperature) in flowing oxygen actually enhances (diminishes) the FM ordering. For these reasons, we have prepared, annealed in different environments, and measured the ensuing magnetization in micrometer and nanoscale ZnO with varying crystallinity. We further find from our magnetization measurements and ab-initio calculations that

  18. Selective d-band Participation in Magnetic and Electronic Behavior of Spin-Ladder Iron-chalcogenides

    Science.gov (United States)

    Caron, Joseph; Neilson, James; Miller, David; Ksenofontov, Vadim; Felser, Claudia; Arpino, Kathrine; Llobet, Anna; McQueen, Tyrel

    2013-03-01

    The mechanism of superconductivity in the iron-based superconductors, particularly the role of magnetism and band nesting, remains controversial. The iron-based superconductors share many properties with the high-Tc cuprates, including two-dimensional layers and proximity to magnetic order. Using reduced dimensionality, as exemplified by the ``spin ladder'' cuprates, we attempt to understand the electronic and magnetic behavior of the AFe2X3 (A= alkali or alkali earth, X = chalcogenide) family of materials. These compounds have 2 × ∞ double-chains (``ladders'') of edge-sharing FeX4 tetrahedra, cutouts of the full two-dimensional Fe2X2 layers of the iron-based superconductors which provide a platform from which to understand the interplay of structure, magnetism, and electronic behavior. The unique properties of these compounds is exemplified by both the inability of DFT programs recapitulate either the underlying physical properties or the dramatic transition from block to stripe magnetic order in Ba1-xKxFe2Se3 that coincides with a change from magnetic to non-magnetic behavior of one d- orbital-derived band. I will also present the influence of pressure and chemical doping on metallic and/or superconducting behavior.

  19. Observation of magnetism in La0.7Sr0.3MnO3—graphene nanoribbons complex: a probable magnetoelectronic material study

    Science.gov (United States)

    Joshi, Anupama; Datar, Suwarna; Kale, S. N.

    2017-07-01

    Incorporation of good magnetic moment and conductivity in a weakly magnetic matrix via doping of an impurity projects huge applications in the domain of magneto-electronics and spintronics. This is quite challenging because the system has to work in unison so that the there is an exchange of electrons and spins between the magnetic grains and the host matrix. Graphene-nano-ribbons (GNRs) possess defect states at their edges and shows good conductivity with weak magnetism. Such systems are studied as host matrix, in which 10% manganite (La0.7Sr0.3MnO3 (LSMO)) has been incorporated using octadecyl-amine (ODA) as the conjugating agent to form a GNR-LSMO complex. While Raman analysis of GNR shows reduction in disorder after complex formation, the system shows magnetic transition at 350 K. The magnetic-force-microscopy shows direct evidence of enhanced magnetism as compared to only GNR, especially in the regions where the manganite grains are in proximity to the GNR matrix. A novel magneto-electronic material can be envisaged with further careful grain-boundary engineering.

  20. Thermoelectric power in carbon nanotubes and quantum wires of nonlinear optical, optoelectronic, and related materials under strong magnetic field : Simplified theory and relative comparison

    NARCIS (Netherlands)

    Ghatak, K.P.; Bhattacharya, S.; Bhowmik, S.; Benedictus, R.; Choudhury, S.

    2008-01-01

    We study thermoelectric power under strong magnetic field (TPM) in carbon nanotubes (CNTs) and quantum wires (QWs) of nonlinear optical, optoelectronic, and related materials. The corresponding results for QWs of III-V, ternary, and quaternary compounds form a special case of our generalized

  1. The effects of various magnetic materials on lamination design for stator-rotor diecasting of induction motors for electric vehicle applications

    Science.gov (United States)

    Elkasabgy, N. M.; Di Pietro, C.

    1994-05-01

    In this paper we describe a novel technique to model induction motors with a diecast stator and rotor and to examine the effects of various magnetic materials on the electrical performance of the motor. For electric vehicle applications, a high volume production operation of the electric motor requires the motor to be small and inexpensive. The expensive labor and material used to manufacture the motor encouraged the researchers to find new methods and techniques to reduce the cost and improve the performance. Diecast rotor and stator windings reduce motor cost and size. For diecasting induction motors, the motor laminations should be designed to optimize the electromagnetic field distribution over the cross section and along the axial direction. The magnetic material used for the laminations should also reduce losses and improve the overall efficiency. A 100 hp four-pole induction motor was modeled with finite elements, the field distribution, the magnetic flux density, and the mechanical performance of the motor were computed using nonlinear magnetostatic and complex steady-state eddy current techniques. The difference in the electrical and mechanical performance of the motor were evaluated for copper and aluminum diecasting. The results show that copper diecasting of the rotor and the stator of the induction motor with magnetic material properties and identified slotting shape is the way to achieve better motor performance and low cost operation.

  2. The effects of various magnetic materials on lamination design for stator-rotor diecasting of induction motors for electric vehicle applications

    Energy Technology Data Exchange (ETDEWEB)

    Elkasabgy, N.M.; Di Pietro, C. [Westinghouse Motor Co. Ltd., Hamilton, Ontario (Canada)

    1994-05-15

    In this paper the authors describe a novel technique to model induction motors with a diecast stator and rotor and to examine the effects of various magnetic materials on the electrical performance of the motor. For electric vehicle applications, a high volume production operation of the electric motor requires the motor to be small and inexpensive. The expensive labor and material used to manufacture the motor encouraged the researchers to find new methods and techniques to reduce the cost and improve the performance. Diecast rotor and stator windings reduce motor cost and size. For diecasting induction motors, the motor laminations should be designed to optimize the electromagnetic field distribution over the cross section and along the axial direction. The magnetic material used for the laminations should also reduce losses and improve the overall efficiency. A 100 hp four-pole induction motor was modeled with finite elements, and the field distribution, the magnetic flux density, and the mechanical performance of the motor were computed using nonlinear magnetostatic and complex steady-state eddy current techniques. The difference in the electrical and mechanical performance of the motor were evaluated for copper and aluminum diecasting. The results show that copper diecasting of the rotor and the stator of the induction motor with magnetic material properties and identified slotting shape is the way to achieve better motor performance and low cost operation. 5 refs.

  3. Sensitivity study of multi-layer active magnetic regenerators using first order magnetocaloric material La(Fe,Mn,Si)13Hy

    DEFF Research Database (Denmark)

    Lei, Tian; Nielsen, Kaspar Kirstein; Engelbrecht, Kurt

    2015-01-01

    We present simulation results of multi-layer active magnetic regenerators using the solid-state refrigerant La(Fe,Mn,Si)13Hy. This material presents a large, however quite sharp, isothermal entropy change that requires a careful choice of number of layers and working temperature for multi...

  4. Designing a magnet for magnetic refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Bjoerk, R.

    2010-03-15

    This thesis investigates the design and optimization of a permanent magnet assembly for use in a magnetic refrigeration device. The heart of magnetic refrigeration is the adiabatic temperature change in the magnetocaloric material which is caused by the magnetic field. In order to design an ideal magnet assembly the magnetocaloric materials and the refrigeration process itself and their properties and performance as a function of magnetic field are investigated. For the magnetocaloric materials it is the magnetization, specific heat capacity and adiabatic temperature that are investigated as functions of the magnetic field. Following this the process utilized by a magnetic refrigerator to provide cooling is investigated using a publicly available one dimensional numerical model. This process is called active magnetic regeneration (AMR). The aim is to determine the performance of the AMR as a function of the magnetic field in order to learn the properties of the optimal magnet assembly. The performance of the AMR as a function of the synchronization and width of the magnetic field with respect to the AMR cycle, the ramp rate and maximum value of the magnetic field are investigated. Other published magnet designs used in magnetic refrigeration devices are also evaluated, using a figure of merit based on the properties of the investigated magnetocaloric materials, to learn the properties of the best magnet designs to date. Following this investigation the Halbach cylinder, which is a hollow permanent magnet cylinder with a rotating remanent flux density, is investigated in detail as it forms the basis of many magnet designs used in magnetic refrigeration. Here the optimal dimensions of a Halbach cylinder, as well as analytical calculations of the magnetic field for a Halbach cylinder of infinite length, are presented. Once it has been determined which properties are desirable for a magnet used in magnetic refrigeration the design of a new magnet is described. This is

  5. Constructed ILs coated porous magnetic nickel cobaltate hexagonal nanoplates sensing materials for the simultaneous detection of cumulative toxic metals

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Yuanyuan; Zhang, Lei, E-mail: zhanglei63@126.com

    2017-07-05

    Highlights: • A novel sensor material based on ionic liquids@nickel cobaltate was constructed. • Various morphologies of NiCo{sub 2}O{sub 4} were synthesized for electrocatalytic comparison. • ILs@NiCo{sub 2}O{sub 4}-P was used to detect cumulative toxic metals for the first time. • The sensor displayed well reproducibility, excellent selectivity and sensitivity. • The method was applied to detect practical samples with satisfactory results. - Abstract: The different morphologies of magnetic nickel cobaltate (NiCo{sub 2}O{sub 4}) electrocatalysts, consisting of nanoparticles (NiCo{sub 2}O{sub 4}-N), nanoplates (NiCo{sub 2}O{sub 4}-P) and microspheres (NiCo{sub 2}O{sub 4}-S) were fabricated. It was found that the electrocatalytic properties of the sensing materials were strongly dependent on morphology and specific surface area. The porous NiCo{sub 2}O{sub 4} hexagonal nanoplates coupled with ILs as modified materials (ILs@NiCo{sub 2}O{sub 4}-P) for the simultaneous determination of thallium (Tl{sup +}), lead (Pb{sup 2+}) and copper (Cu{sup 2+}), exhibited high sensitivity, long-time stability and good repeatability. The enhanced electrocatalytic activity was attributed to relatively large specific surface area, excellent electronic conductivity, and unique porous nanostructure. The analytical performance of the constructed electrode on detection of Tl{sup +}, Pb{sup 2+} and Cu{sup 2+} was examined using differential pulse anodic stripping voltammetry (DPASV). Under optimal conditions, the electrode showed a good linear response to Tl{sup +}, Pb{sup 2+}and Cu{sup 2+} in the concentration range of 0.1–100.0, 0.1–100.0 and 0.05–100.0 μg/L, respectively. The detection limits (S/N = 3) were 0.046, 0.034 and 0.029 μg/L for Tl{sup +}, Pb{sup 2+} and Cu{sup 2+}, respectively. The fabricated sensor was successfully applied to detect trace Tl{sup +}, Pb{sup 2+} and Cu{sup 2+} in various water and soil samples with satisfactory results. Hence, this work

  6. Magnetic nanocomposites.

    Science.gov (United States)

    Behrens, Silke; Appel, Ingo

    2016-06-01

    Magnetic nanocomposites are multi-component materials, typically containing nanosized magnetic materials to trigger the response to an external stimulus (i.e., an external static or alternating magnetic field). Up to now, the search for novel nanocomposites has lead to the combination of a plethora of different materials (e.g., gels, liquid crystals, renewable polymers, silica, carbon or metal organic frameworks) with various types of magnetic particles, offering exciting perspectives not only for fundamental investigations but also for application in various fields, including medical therapy and diagnosis, separations, actuation, or catalysis. In this review, we have selected a few of the most recent examples to highlight general concepts and advances in the preparation of magnetic nanocomposites and recent advances in the synthesis of magnetic nanoparticles. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. RICE HUSK SILICA-COATED MAGNETIC PARTICLES AS A LOW COST SUPPORT MATERIAL FOR CRUDE Pseudomonas aeruginosa LIPASE IMMOBILIZATION

    Directory of Open Access Journals (Sweden)

    Noor Hindryawati

    2016-11-01

    Full Text Available In this research, lipase produced from the bacteria Pseudomonas aeruginosa was immobilized on rice husk silica-coated Fe3O4 nanoparticles. The process included the following steps: preparation of magnetic ferosoferic oxide nanoparticles (NP, coating NP with silica from rice husk ash, activation with glutaraldehyde and covalent immobilization of lipase on the support. The synthesis of the nanoparticle was followed by characterization through FT-IR, XRD, and FE-SEM. The hydrolysis kinetics (using 4-Nitrophenyl palmitate as a substrate of the immobilized lipase followed Michaelis-Menten model with a Vmax and a Km value of 4.0 mM.s-1 and 0.63 mM, respectively. The immobilized lipase showed better tolerance to extreme temperature and pH compared to free lipase. About 60% of enzyme remained immobilized after ten cycles of reuse and 68.13% of it were stable until 49 days. Thus the silica-coated Fe3O4 nanoparticles appeared to be a potential support material for lipase immobilization applications.

  8. Magnetic Susceptibility Study of Sub-Pico-emu Sample Using a Micromagnetometer: An Investigation through Bistable Spin-Crossover Materials.

    Science.gov (United States)

    Kamara, Souleymane; Tran, Quang-Hung; Davesne, Vincent; Félix, Gautier; Salmon, Lionel; Kim, Kunwoo; Kim, CheolGi; Bousseksou, Azzedine; Terki, Ferial

    2017-12-01

    A promising and original method to study the spin-transition in bistable spin-crossover (SCO) materials using a magnetoresistive multiring sensor and its self-generated magnetic field is reported. Qualitative and quantitative studies are carried out combining theoretical and experimental approaches. The results show that only a small part of matter dropped on the sensor surface is probed by the device. At a low bias-current range, the number of detected nanoparticles depends on the amplitude of the current. However, in agreement with the theoretical model, the stray voltage from the particles is proportional to the current squared. By changing both the bias current and the concentration of particle droplet, the thermal hysteresis of an ultrasmall volume, 1 × 10-4 mm3 , of SCO particles is measured. The local probe of the experimental setup allows a highest resolution of 4 × 10-14 emu to be reached, which is never achieved by experimental methods at room temperature. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Materials Science Laboratory - Columnar-to-Equiaxed Transition in Solidification Processing and Microstructure Formation in Casting of Technical Alloys under Diffusive and Magnetically Controlled Convective Conditions

    Science.gov (United States)

    Gandin, Charles-Andre; Ratke, Lorenz

    2008-01-01

    The Materials Science Laboratory - Columnar-to-Equiaxed Transition in Solidification Processing and Microstructure Formation in Casting of Technical Alloys under Diffusive and Magnetically Controlled Convective Conditions (MSL-CETSOL and MICAST) are two investigations which supports research into metallurgical solidification, semiconductor crystal growth (Bridgman and zone melting), and measurement of thermo-physical properties of materials. This is a cooperative investigation with the European Space Agency (ESA) and National Aeronautics and Space Administration (NASA) for accommodation and operation aboard the International Space Station (ISS). Research Summary: Materials Science Laboratory - Columnar-to-Equiaxed Transition in Solidification Processing (CETSOL) and Microstructure Formation in Casting of Technical Alloys under Diffusive and Magnetically Controlled Convective Conditions (MICAST) are two complementary investigations which will examine different growth patterns and evolution of microstructures during crystallization of metallic alloys in microgravity. The aim of these experiments is to deepen the quantitative understanding of the physical principles that govern solidification processes in cast alloys by directional solidification.

  10. Magnetic-field-induced separation of materials: Ferrofluids and their applications in energy-saving separation processes; Magnetfeldinduzierte Stoffabtrennung: Ferrofluide und deren Einsatz in energiesparenden Trennverfahren

    Energy Technology Data Exchange (ETDEWEB)

    Lammerschop, O.; Roth, M.

    2002-07-01

    Selective separation of substances contained in mixes is a challenge in many technical and medical appications. If it were possible to couple or decouple substances to and from magnetic carriers, ferrofluids could be used in a cycle process for separation and accumulation of materials. Investigations to this end comprised the addition of a surface-modified ferrofluid to a material mix, where the materials to be separated will be deposited on the ferrofluid. After this, the magnetic particles of magnetic dispersion will be separated. Once the substance and the ferrofluid resp. the magnetic particles have been separated, the latter can be returned to the cycle process. (orig.) [German] Die gezielte Abtrennung von Substanzen aus Stoffgemischen ist eine Herausforderung, welche sich bei vielen technischen und medizinischen Aufgaben stellt. Gelaenge es, Substanzen an magnetische Traeger sowohl gezielt an- als auch abzukoppeln, so koennten Ferrofluide in einem Kreisprozess zur Abtrennung und Anreicherung von Stoffen eingesetzt werden. Oben dargestellt ist die diesem Bericht zugrunde liegende Idee der Abtrennung von Wertstoffen mittels Ferrofluiden unter Aufbereitung und Rueckfuehrung der magnetischen Partikel. Einem Stoffgemisch wird ein oberflaechenmodifiziertes Ferrofluid zugegeben, welches gezielt die abzutrennenden Stoffe anlagert. Anschliessend erfolgt eine Abtrennung der magnetischen Partikel oder der magnetischen Dispersion. Nach erfolgter Trennung von Substanz und Ferrofluid bzw. magnetischen Partikeln koennen letztere erneut im Kreisprozess eingesetzt werden. (orig.)

  11. Characterization of Fe-doped In-Sb-Te (Fe: 10 at.% material with individual electrical-phase-change and magnetic properties

    Directory of Open Access Journals (Sweden)

    Young Mi Lee

    2011-06-01

    Full Text Available We propose a new electrical-phase-change magnetic material, namely Fe-doped In-Sb-Te (FIST, for possible non-volatile multi-bit memory applications. FIST was formed by typical co-sputter method with Fe 10 at.% doping in In3Sb1Te2. FIST offers the electrical-phase-change and magnetic properties by way of the change of In 4d chemical bonding density and embedded Fe nanoclusters with the size of 4∼5 nm, respectively. It maintained the amorphous phase on the electrical-phase-change. Chemical state of In was only changed to increase the density of In-In chemical bonding during the electrical-phase-change without Fe nanoclusters contribution. Also, the magnetic property by Fe nanoclusters was not changed by the electrical-phase-change. On this basis, we propose the FIST material with the individual electrical-phase-change and magnetic properties for the multi-bit nonvolatile memory materials.

  12. Magnetic solid-phase extraction using nanoporous three dimensional graphene hybrid materials for high-capacity enrichment and simultaneous detection of nine bisphenol analogs from water sample.

    Science.gov (United States)

    Wang, Lingling; Zhang, Zhenzhen; Zhang, Jing; Zhang, Lei

    2016-09-09

    The synthesis of a magnetic nanoporous three dimensional graphene (3DG)/ZnFe2O4 composite has been achieved. Through formation of graphene hydrogel, ZnFe2O4 magnetic particles was successfully introduced into the nanoporous 3DG, resulting in a magnetic porous carbon material. The morphology, structure, and magnetic behavior of the as-prepared 3DG/ZnFe2O4 were characterized by using the techniques of SEM, XRD, BET, VSM, FTIR, Raman and TGA. The 3DG/ZnFe2O4 has a high specific surface area and super paramagnetism. Its performance was evaluated by the magnetic solid-phase extraction of nine bisphenol analogs (BPs) from water samples followed by HPLC analysis, and showed excellent adsorption capability for the nine target compounds. Under optimized condition, the lower method detection limits (0.05-0.18ngmL(-1)), the higher enrichment factors (800 fold) and good recoveries (95.1-103.8%) with relative standard deviation (RSD) values less than 6.2% were achieved. The results indicated that the developed method based on the use of 3DG/ZnFe2O4 as the magnetic adsorbent has the advantages of convenience and high efficiency, and can be successfully applied to detect the nine BPs in real water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Organic Light-Emitting Diodes (OLEDs) and Optically-Detected Magnetic Resonance (ODMR) studies on organic materials

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Min [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    Organic semiconductors have evolved rapidly over the last decades and currently are considered as the next-generation technology for many applications, such as organic light-emitting diodes (OLEDs) in flat-panel displays (FPDs) and solid state lighting (SSL), and organic solar cells (OSCs) in clean renewable energy. This dissertation focuses mainly on OLEDs. Although the commercialization of the OLED technology in FPDs is growing and appears to be just around the corner for SSL, there are still several key issues that need to be addressed: (1) the cost of OLEDs is very high, largely due to the costly current manufacturing process; (2) the efficiency of OLEDs needs to be improved. This is vital to the success of OLEDs in the FPD and SSL industries; (3) the lifetime of OLEDs, especially blue OLEDs, is the biggest technical challenge. All these issues raise the demand for new organic materials, new device structures, and continued lower-cost fabrication methods. In an attempt to address these issues, we used solution-processing methods to fabricate highly efficient small molecule OLEDs (SMOLEDs); this approach is costeffective in comparison to the more common thermal vacuum evaporation. We also successfully made efficient indium tin oxide (ITO)-free SMOLEDs to further improve the efficiency of the OLEDs. We employed the spin-dependent optically-detected magnetic resonance (ODMR) technique to study the luminescence quenching processes in OLEDs and organic materials in order to understand the intrinsic degradation mechanisms. We also fabricated polymer LEDs (PLEDs) based on a new electron-accepting blue-emitting polymer and studied the effect of molecular weight on the efficiency of PLEDs. All these studies helped us to better understand the underlying relationship between the organic semiconductor materials and the OLEDs’ performance, and will subsequently assist in further enhancing the efficiency of OLEDs. With strongly improved device performance (in addition to

  14. Solid-State Precursor Routes to Iii-V Type Electronic (13-15) and Magnetic (3-15) Materials

    Science.gov (United States)

    Treece, Randolph Edward

    An interest in electronic materials has led me to investigate new synthetic approaches to "III-V" type semiconducting (13-15, current IUPAC designation for B and N groups in the Periodic Table) and magnetic (3-15) compounds. It is now possible to prepare binary (GaAs and GdP) and ternary mixed-metal (Al_ {x}Ga_{1-x}As) and mixed -pnictide (rm GaP_{x}As_ {1-x}) compounds in seconds from rapid, low-temperature-initiated metathesis reactions between a metal (III) trihalide and a trisodium pnictide, exemplified by MX_3 + Na_3Pn to MPn + 3 NaX, where M is Al, Ga, In, (Al,Ga), or a lanthanide; X is F, Cl, or I; and Pn is P, As, Sb, or (P,As). The precursors are mixed together in a dry box and ignited by light grinding with a mortar and pestle, or by brief, local heating from a hot filament. These reactions are very exothermic (calculated Delta H_{rxn} (GaAs) = -138 kcal/mol) and typically reach temperatures in excess of 700^circ C within seconds of initiation, and cool to room temperature in less than 15 seconds. The byproduct sodium halide is simply removed by washing with water or methanol, leaving the polycrystalline "III-V" products. In spite of the brief and explosive nature of these reactions, there are some clues as to the initiation and reaction processes. The initial steps in the reactions appear to be the decomposition of the precursors and the formation of the sodium halides. Since initiation occurs when one of the precursors goes through a phase change, such as melting or decomposing, the melting points of the GaX_3 precursors are good indicators of how easily the reactions can be initiated. Physical methods have been employed to characterize the bulk products. The 13-15 materials have been investigated using MAS-NMR spectroscopy. The 3-15 compounds have been extensively studied using magnetometry, and the effectiveness of the metathesis processes was examined by comparing the ignition reaction products to those generated by direct combination of the elements

  15. Magnetic hysterysis evolution of Ni-Al alloy with Fe and Mn substitution by vacuum arc melting to produce the room temperature magnetocaloric effect material

    Energy Technology Data Exchange (ETDEWEB)

    Notonegoro, Hamdan Akbar [PPS Materials Science, FMIPA-Universitas Indonesia, Depok 16424 (Indonesia); Mechanical Engineering Dept., FT-Universitas Sultan Ageng Tirtayasa, Cilegon 42435 (Indonesia); Kurniawan, Budhy; Manaf, Azwar, E-mail: azwar@sci.ui.ac.id [PPS Materials Science, FMIPA-Universitas Indonesia, Depok 16424 (Indonesia); Setiawan, Jan [Center for Nuclear Fuel Tecnology-Badan Tenaga Atom Nasional, Tangerang Selatan 15310 (Indonesia)

    2016-06-17

    The development of magnetocaloric effect (MCE) material is done in order to reduce the damage of the ozone layer caused by the chlorofluorocarbons (CFCs) emitted into the air. The research dealing with synthesis of magnetocaloric materials based of Ni-Al Heusler Alloy structure and by varying substitution some atoms of Ni with Fe and Al with Mn on Ni-Al Heusler Alloy structure to become Ni{sub 44}Fe{sub 6}Mn{sub 32}Al{sub 18}. Vacuum Arc Melting (VAM) equipment is used to form the alloys on vacuum condition and by flowing argon gas atmosphere and then followed by annealing process for 72 hours. X-Ray Diffraction (XRD) reveals that crystallite structure of material is observed. We define that Ni{sub 44}Fe{sub 6} as X{sub 2}, Mn{sub 25} as Y, and Al{sub 18}Mn{sub 7} as Z. Based on the XRD result, we observed that the general formula X{sub 2}YZ is not changed. The PERMAGRAF measurement revealed that there exists of magnetic hysterysis. The hysterysis show that the magnetic structures of the system undego evolution from diamagnetic to soft ferromagnetic material which all of the compound have the same crystallite structure. This evolution indicated that the change in the composition has led to changes the magnetic composition. Mn is the major element that gives strong magnetic properties to the sample. When Mn partially replaced position of Al, the sample became dominant to be influenced to improve their magnetic properties. In addition, substitution a part of Ni by Fe in the composition reveals a pinning of the domain walls in the sample.

  16. Lack of multiferroic behavior in BaCuSi2O6 is consistent with the frustrated magnetic scenario for this material

    Energy Technology Data Exchange (ETDEWEB)

    Zapf, Vivien [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Jaime, Marcelo [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chikara, Shalinee [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Fisher, Ian [Stanford Univ., CA (United States); Batista, C. D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)

    2017-03-01

    BaCuSi2O6 is a well-known quantum magnet that exhibits a Bose-Einstein Condensation quantum phase transition in applied magnetic fields. It contains Cu dimers that form singlets in zero magnetic field, and in applied fields as the singlet-triplet gap is suppressed a quantum phase transition occurs to canted XY antiferromagnetism between critical fields Hc1 = 23 T and Hc2 = 59 T. In addition, as the temperature is lowered, a rare frustrationinduced dimensional reduction has been proposed from three to two dimensions. Recently, however, a controversy has arisen about the details of the magnetic ordering due to the discovery of a tetragonal to orthorhombic structural transition at 100 K with an incommensurate modulation along the b-axis. Multiple magnon modes were observed in neutron diffraction studies, while NMR found modulation of the spin structure along both the ab plane and the c-axis. In this scenario the material is still a Bose-Einstein condensate system but the frustration is not perfect, calling into question the dimension reduction scenario. A recent study of BaCuSi2O6 combining inelastic neutron diffraction and density functional theory suggest that the material isn’t even frustrated at all and that the spins are ordered ferromagnetically in the a-b plane and antiferromagnetically along the c-axis. After a detailed symmetry analysis we have concluded that the magnetic scenario postulated by this most recent unfrustrated theory6 will render BaCuSi2O6 a multiferroic between Hc1 and Hc2, with electric polarization in easy axis of the a-b plane for magnetic fields along the c-axis via an inverse Dzyaloshinskii-Moriya mechanism. Electric polarization is a sensitive symmetry probe of magnetic order, since magnetic systems that break spatial inversion symmetry can induce an overall ferroelectricity in the crystalline lattice. In pulsed magnetic fields

  17. Study of the rare-earth metals magnetic powders filling influence on the basic properties of elastomeric materials

    Science.gov (United States)

    Zhansakova, K. S.; Mitryaeva, N. S.; Russkikh, G. S.

    2017-08-01

    The work deals with the studying of technological, vulcanization and physical-mechanical properties of magnetic elastomeric compositions. Powders of rare-earth metals with different morphology of particles and different magnetic characteristics were used as fillers. Based on the results of the work performed, it was revealed that the applied technology of manufacturing magnetic elastomeric compositions based on synthetic rubber is optimal. The rationale for this is the balanced technological and physical-mechanical properties of vulcanizates. Morphology and magnetic characteristics of fillers also do not significantly change the vulcanization properties.

  18. Evaluation of different magnetic resonance imaging contrast materials to be used as dummy markers in image-guided brachytherapy for gynecologic malignancies

    Energy Technology Data Exchange (ETDEWEB)

    Sales, Camila Pessoa; Carvalho, Heloisa de Andrade; Rubo, Rodrigo Augusto; Stuart, Silvia Radwanski; Rodrigues, Laura Natal, E-mail: camyps@gmail.com [Universidade de Sao Paulo (InRad/HC/FM/USP), Sao Paulo, SP (Brazil). Faculdade de Medicina. Instituto de Radiologia; Taverna, Khallil Chaim; Pastorello, Bruno Fraccini [Universidade de Sao Paulo (FM/USP), Sao Paulo, SP (Brazil). Departamento de Radiologia e Oncologia. Lab. de Ressonancia Magnetica em Neurorradiologia; Borgonovi, Arthur Felipe [Royal Philips Electronics, Eindhoven (Netherlands)

    2016-05-15

    Objective: to identify a contrast material that could be used as a dummy marker for magnetic resonance imaging. Materials and methods: magnetic resonance images were acquired with six different catheter-filling materials - water, glucose 50%, saline, olive oil, glycerin, and copper sulfate (CuSO{sub 4}) water solution (2.08 g/L) - inserted into compatible computed tomography/magnetic resonance imaging ring applicators placed in a phantom made of gelatin and CuSO{sub 4}. The best contrast media were tested in four patients with the applicators in place. Results: in T2-weighted sequences, the best contrast was achieved with the CuSO{sub 4}-filled catheters, followed by saline- and glycerin-filled catheters, which presented poor visualization. In addition (also in T2-weighted sequences), CuSO{sub 4} presented better contrast when tested in the phantom than when tested in the patients, in which it provided some contrast but with poor identification of the first dwell position, mainly in the ring. Conclusion: we found CuSO{sub 4} to be the best solution for visualization of the applicator channels, mainly in T2-weighted images in vitro, although the materials tested presented low signal intensity in the images obtained in vivo, as well as poor precision in determining the first dwell position. (author)

  19. Studies of structural, morphological, electrical, and magnetic properties of Mg-substituted Co-ferrite materials synthesized using sol-gel autocombustion method

    Science.gov (United States)

    Mammo, Tulu Wegayehu; Murali, N.; Sileshi, Yonatan Mulushoa; Arunamani, T.

    2017-10-01

    In this work,a nonmagnetic Mg partially substituted in CoFe2O4 was considered and has been shown to have an impact on structural, electrical and magnetic properties of ferrite materials with Co1-xMgxFe2O4 (x = 0, 0.25, 0.45, and 0.75) forms. Sol-gel synthesis route has been followed to synthesize these materials using citric acid as a fuel. Structural parameters were calculated from powder X-ray diffraction data. X-ray diffraction revealed that all the samples synthesized are pure cubic spinel structured materials with space group of Fd 3 ̅m and the lattice constant varying with Mg concentration. From the field emission scanning electron microscopy (FESEM) microstructure characterizations it has been shown that the synthesized materials are well defined crystalline structured with inhomogeneous grain sizes. Besides, the grain sizes were shown to decrease with increase of Mg-content. Fourier transform Infrared (FT-IR) characterization showed the cation vibrations and stretching of other groups in the wave number range of 400-4000 cm-1. The DC resistivity measurements showed an enhanced resistivity of the samples, in the order of 107 Ω cm, at the highest concentration of Mg. VSM magnetic properties analysis revealed that the Coercive force decreases with increase of Mg concentration whereas the saturation magnetization varies with Mg content.

  20. Evaluation of different magnetic resonance imaging contrast materials to be used as dummy markers in image-guided brachytherapy for gynecologic malignancies

    Directory of Open Access Journals (Sweden)

    Camila Pessoa Sales

    2016-06-01

    Full Text Available Abstract Objective: To identify a contrast material that could be used as a dummy marker for magnetic resonance imaging. Materials and Methods: Magnetic resonance images were acquired with six different catheter-filling materials-water, glucose 50%, saline, olive oil, glycerin, and copper sulfate (CuSO4 water solution (2.08 g/L-inserted into compatible computed tomography/magnetic resonance imaging ring applicators placed in a phantom made of gelatin and CuSO4. The best contrast media were tested in four patients with the applicators in place. Results: In T2-weighted sequences, the best contrast was achieved with the CuSO4-filled catheters, followed by saline- and glycerin-filled catheters, which presented poor visualization. In addition (also in T2-weighted sequences, CuSO4 presented better contrast when tested in the phantom than when tested in the patients, in which it provided some contrast but with poor identification of the first dwell position, mainly in the ring. Conclusion: We found CuSO4 to be the best solution for visualization of the applicator channels, mainly in T2-weighted images in vitro, although the materials tested presented low signal intensity in the images obtained in vivo, as well as poor precision in determining the first dwell position.