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Abstract
The magnetic properties of various families of nanocomposite materials containing nanoparticles of transition metals or transition-metal compounds are reviewed here. The investigated magnetic nanocomposites include materials produced either by dissolving a ferrofluid containing pre-formed nanoparticles of desired composition and size in a fluid resin submitted to subsequent curing treatment, or by generating the nanoparticles during the very synthesis of the embedding matrix. Two typical examples of these production methods are polymer nanocomposites and ceramic nanocomposites. The resulting magnetic properties turn out to be markedly different in these two classes of nanomaterials. The control of nanoparticle size, distribution, and aggregation degree is easier in polymer nanocomposites, where the interparticle interactions can either be minimized or exploited to create magnetic mesostructures characterized by anisotropic magnetic properties; the ensuing applications of polymer nanocomposites as sensors and in devices for Information and Communication Technologies (ICT) are highlighted. On the other hand, ceramic nanocomposites obtained from transition-metal loaded zeolite precursors exhibit a remarkably complex magnetic behavior originating from the simultaneous presence of zerovalent transition-metal nanoparticles and transition-metal ions dissolved in the matrix; the applications of these nanocomposites in biomedicine and for pollutant remediation are briefly discussed.
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Magnetic states of nanostructures containing Ni 2+ ions at the surface of SiO 2 nanospheres. Sci Rep 2017; 7:10822. [PMID: 28883451 PMCID: PMC5589877 DOI: 10.1038/s41598-017-11394-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 08/17/2017] [Indexed: 12/05/2022] Open
Abstract
Ultra-small magnetic particles containing Ni2+ ions were grown at the surface of SiO2 spheroidal nanoparticles (typical diameter: 50 nm) starting from NiCl2 solutions. Depending on preparation details, two samples characterized by magnetic sub-nanostructures or lamellar sub-nanoparticles at the SiO2 nanosphere surface were obtained. The decorated SiO2 nanospheres were submitted to physico-chemical and magnetic characterization. In both samples, a magnetically blocked phase is observed at low temperature. Below 5 K, discontinuities in isothermal magnetization loops and magnetic relaxation effects suggest the onset of coherent quantum tunneling of nanoparticle magnetization (QTM). Relaxation effects give are described by a field- and temperature-dependent magnetic viscosity SV(H,T); the total spin number of magnetic units is estimated by fitting the isothermal SV(H) curve to a model for an assembly of particles with random anisotropy axes. The mean number of aligned spins involved in the low-temperature relaxation is 32 and 15 in the two considered samples. Phonon-assisted QTM plays an increasingly important role with raising temperature and the quantum regime gradually merges with the classical behavior. Above the blocking temperature the magnetic units behave as classical superparamagnetic particles. When the intra-particle ferromagnetic order disappears the Ni2+ ions respond individually to the magnetic field.
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Metal-organic framework: Structure and magnetic properties of [Cu3(BTC)2 (L)x·(CuO)y]n (L=H2O, DMF). J SOLID STATE CHEM 2017. [DOI: 10.1016/j.jssc.2017.05.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Gonçalves ES, Cornejo DR, Oliveira CLP, Figueiredo Neto AM, Depeyrot J, Tourinho FA, Aquino R. Magnetic and structural study of electric double-layered ferrofluid with MnFe(2)O(4)@γ-Fe(2)O(3) nanoparticles of different mean diameters: Determination of the magnetic correlation distance. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:042317. [PMID: 25974501 DOI: 10.1103/physreve.91.042317] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Indexed: 06/04/2023]
Abstract
Magnetic fluids based on manganese ferrite nanoparticles were studied from the structural point of view through small angle x-rays scattering (SAXS) and from the magnetic point of view through zero-field cooling and field cooling (ZFC-FC) and ac susceptibility measurements (MS). Three different colloids with particles mean diameters of 2.78,3.42, and 6.15 nm were investigated. The size distribution obtained from SAXS measurements follows a log-normal behavior. The ZFC-FC and MS results revealed the presence of an important magnetic interaction between the nanoparticles, characterized by a magnetic correlation distance Λ. The colloidal medium can be pictures as composed by magnetic cluster constituted by N interacting particles. These magnetic clusters are not characterized by a physical aggregation of particles. The energy barrier energy obtained is consistent with the existence of this magnetic clusters. Besides the magnetic interaction between particles, confinement effects must be included to account for the experimental values of the magnetic energy barrier encountered.
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Affiliation(s)
- E S Gonçalves
- Instituto de Física, Universidade de São Paulo, São Paulo, Brazil
| | - D R Cornejo
- Instituto de Física, Universidade de São Paulo, São Paulo, Brazil
| | - C L P Oliveira
- Instituto de Física, Universidade de São Paulo, São Paulo, Brazil
| | | | - J Depeyrot
- Instituto de Física, Universidade de Brasília, Brasília, Brazil
| | - F A Tourinho
- Instituto de Química, Universidade de Brasília, Brasília, Brazil
| | - R Aquino
- Faculdade UnB Planaltina, Universidade de Brasília, Brasília, Brazil
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Perovic M, Kusigerski V, Mrakovic A, Spasojevic V, Blanusa J, Nikolic V, Schneeweiss O, David B, Pizúrová N. The glassy behaviour of poorly crystalline Fe2O3 nanorods obtained by thermal decomposition of ferrous oxalate. NANOTECHNOLOGY 2015; 26:115705. [PMID: 25722041 DOI: 10.1088/0957-4484/26/11/115705] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Nanorod ferrous oxalate dihydrate (FeC2O4 × 2H2O) which had been synthesized by the microemulsion method, was used as a precursor in the thermal decomposition process performed in air atmosphere. The formation of nanocrystalline hematite as the final product was preceded by the appearence of an intermediate product. Comprehensive study comprising several complementary techniques (x-ray diffraction, transmission electron microscopy, selected area electron diffraction, thermogravimetric/differential thermal analyses and SQUID magnetometry) confirmed that the intermediate product corresponds to the poorly crystalline Fe2O3. Due to the specific nanorod shape and poorly crystalline structure, the investigated Fe2O3 showed high coercive field value of ~0.5 T at 5 K. Special attention in this study was devoted to the peculiar magnetic properties of poorly crystalline Fe2O3, which were thoroughly investigated by employing sophisticated experimental procedures such as relaxation of thermoremanent magnetization for different cooling fields, zero field and field cooled memory effects as well as aging experiments for different waiting times. At low temperatures and weak applied magnetic fields, the investigated system behaves similarly to spin glasses, manifesting slow, collective relaxation dynamics of magnetic moments through memory, rejuvenation and aging effects.
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Sangermano M, Allia P, Tiberto P, Barrera G, Bondioli F, Florini N, Messori M. Photo-Cured Epoxy Networks Functionalized With Fe3O4Generated by Non-hydrolytic Sol-Gel Process. MACROMOL CHEM PHYS 2012. [DOI: 10.1002/macp.201200494] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Quantum tunneling of magnetization in ultrasmall half-metallic V3O4 quantum dots: displaying quantum superparamagnetic state. Sci Rep 2012; 2:755. [PMID: 23091695 PMCID: PMC3477649 DOI: 10.1038/srep00755] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 09/06/2012] [Indexed: 11/08/2022] Open
Abstract
Quantum tunneling of magnetization (QTMs), stemming from their importance for understanding materials with unconventional properties, has continued to attract widespread theoretical and experimental attention. However, the observation of QTMs in the most promising candidates of molecular magnets and few iron-based compounds is limited to very low temperature. Herein, we first highlight a simple system, ultrasmall half-metallic V(3)O(4) quantum dots, as a promising candidate for the investigation of QTMs at high temperature. The quantum superparamagnetic state (QSP) as a high temperature signature of QTMs is observed at 16 K, which is beyond absolute zero temperature and much higher than that of conventional iron-based compounds due to the stronger spin-orbital coupling of V(3+) ions bringing high anisotropy energy. It is undoubtedly that this ultrasmall quantum dots, V(3)O(4), offers not only a promising candidate for theoretical understanding of QTMs but also a very exciting possibility for computers using mesoscopic magnets.
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Coker VS, Telling ND, van der Laan G, Pattrick RAD, Pearce CI, Arenholz E, Tuna F, Winpenny REP, Lloyd JR. Harnessing the extracellular bacterial production of nanoscale cobalt ferrite with exploitable magnetic properties. ACS NANO 2009; 3:1922-1928. [PMID: 19507866 DOI: 10.1021/nn900293d] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Nanoscale ferrimagnetic particles have a diverse range of uses from directed cancer therapy and drug delivery systems to magnetic recording media and transducers. Such applications require the production of monodisperse nanoparticles with well-controlled size, composition, and magnetic properties. To fabricate these materials purely using synthetic methods is costly in both environmental and economical terms. However, metal-reducing microorganisms offer an untapped resource to produce these materials. Here, the Fe(III)-reducing bacterium Geobacter sulfurreducens is used to synthesize magnetic iron oxide nanoparticles. A combination of electron microscopy, soft X-ray spectroscopy, and magnetometry techniques was employed to show that this method of biosynthesis results in high yields of crystalline nanoparticles with a narrow size distribution and magnetic properties equal to the best chemically synthesized materials. In particular, it is demonstrated here that cobalt ferrite (CoFe(2)O(4)) nanoparticles with low temperature coercivity approaching 8 kOe and an effective anisotropy constant of ∼10(6) erg cm(-3) can be manufactured through this biotechnological route. The dramatic enhancement in the magnetic properties of the nanoparticles by the introduction of high quantities of Co into the spinel structure represents a significant advance over previous biomineralization studies in this area using magnetotactic bacteria. The successful production of nanoparticulate ferrites achieved in this study at high yields could open up the way for the scaled-up industrial manufacture of nanoparticles using environmentally benign methodologies.
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Affiliation(s)
- Victoria S Coker
- School of Earth, Atmospheric and Environmental Sciences and Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester, M13 9PL, U.K
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Abu-Much R, Gedanken A. Sonochemical Synthesis under a Magnetic Field: Fabrication of Nickel and Cobalt Particles and Variation of Their Physical Properties. Chemistry 2008; 14:10115-22. [DOI: 10.1002/chem.200801469] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Pajić D, Zadro K, Ristić R, Zivković I, Skoko Z, Babić E. Thermal relaxation of magnetic clusters in amorphous Hf(57)Fe(43) alloy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2007; 19:296207. [PMID: 21483078 DOI: 10.1088/0953-8984/19/29/296207] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The magnetization processes in binary magnetic/non-magnetic amorphous alloy Hf(57)Fe(43) are investigated by the detailed measurement of magnetic hysteresis loops, temperature dependence of magnetization, relaxation of magnetization and magnetic ac susceptibility, including a nonlinear term. Blocking of magnetic moments at lower temperatures is accompanied by the slow relaxation of magnetization and magnetic hysteresis loops. All of the observed properties are explained by the superparamagnetic behaviour of the single domain magnetic clusters inside the non-magnetic host, their blocking by the anisotropy barriers and thermal fluctuation over the barriers accompanied by relaxation of magnetization. From magnetic viscosity analysis based on thermal relaxation over the anisotropy barriers it is found that magnetic clusters occupy the characteristic volume from 25 up to 200 nm(3). The validity of the superparamagnetic model of Hf(57)Fe(43) is based on the concentration of iron in the Hf(100-x)Fe(x) system that is just below the threshold for long range magnetic ordering. This work also throws more light on the magnetic behaviour of other amorphous alloys.
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Affiliation(s)
- Damir Pajić
- Department of Physics, Faculty of Science, University of Zagreb, Bijenička cesta 32, HR-10000 Zagreb, Croatia
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Yang Z, Gu H, Du J, Gao J, Zhang B, Zhang X, Xu B. Self-assembled hybrid nanofibers confer a magnetorheological supramolecular hydrogel. Tetrahedron 2007. [DOI: 10.1016/j.tet.2007.02.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Zheng RK, Gu H, Xu B, Zhang XX. The origin of the non-monotonic field dependence of the blocking temperature in magnetic nanoparticles. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2006; 18:5905-5910. [PMID: 21690806 DOI: 10.1088/0953-8984/18/26/010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The dependence of the peak temperature (T(P)) of the zero-field-cooled (ZFC) magnetization curves on the field in a magnetic nanoparticle system was studied using a diluted magnetic fluid composed of FePt nanoparticles. We found that the peak temperature increases with increasing applied field below 3 kOe; it then decreases when the applied field is increased further. We attribute the non-monotonic field dependence of the peak temperature to the anisotropic energy barrier distribution of the particles and to the slow decrease of high-field magnetization above the blocking temperature. Numerical simulations, based on magnetic dynamics, agree well with our experimental results.
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Affiliation(s)
- R K Zheng
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People's Republic of China
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Wen G, Zhao H, Zhao J, Zhang X. Magnetoresistance in as-deposited CoCu granular films. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2001. [DOI: 10.1016/s0928-4931(01)00300-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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