Synthesis of nickel zinc ferrite nanoparticle/organic hybrid from metalorganics
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(Ni,Zn)Fe2O4 particle/organic hybrid was synthesized in situ from metalorganics below 100 °C. A mixture of nickel (II) acetylacetonate (NA), zinc acetylacetonate (ZA), and iron (III) 3-allylacetylacetonate (IAA) was hydrolyzed and polymerized yielding a spinel oxide particle/organic hybrid. X-ray diffraction analysis revealed that the crystallinity of spinel particles was dependent upon the hydrolysis conditions of NA-ZA-IAA. Nanocrystalline nickel zinc ferrite particles below 5 nm were uniformly dispersed in the organic matrix. The magnetization of hybrid increased with an increasing amount of water for hydrolysis. Nano-sized nickel zinc ferrite particle/organic hybrid showed a magnetization-applied field (BH) curve with no remanence above 40 K. The magnetization versus H/T curves from 40 to 100 K were superimposed on the same curve and satisfied the Langevin equation. The remanent magnetization and coercive field of the hybrid were 7.2 emu/g and 150 Oe, respectively, at 4.2 K. The absorption edge of the hybrid was blue-shifted compared with that of bulk ferrite. I. INTRODUCTION
Inorganic/organic hybrid materials are composed of various types of each phase, such as molecule, particle, and matrix, and have attracted special attention.1 Magnetic particle/organic hybrid material consists of nanosized inorganics and organic matrix and is characterized by magnetic particles chemically bonded to the organic matrix. Magnetic particle/organic composites are expected for applications in recording media,2 printing agent, ferrofluid,3 magnetic resonance imaging,4 and thermomagnetic surgery.5 Nanocrystalline magnetic particles show size effects such as superparamagnetism3 and quantum confinement effect.6 The properties of nanosized magnet are combined with the beneficial properties of organics, such as flexibility and malleability, in the hybrid materials. Nickel zinc ferrite is one of the soft magnetic materials and has high permeability and low loss. Because of high electrical resistivity and good magnetic properties, nickel zinc ferrite has attractive applications in microwave devices.7 Magnetic properties of nickel zinc ferrite are known to depend upon the Ni/Zn ratios. Nickel zinc ferrite exhibits the highest saturation magnetization at Ni0.5Zn0.5Fe2O4 composition.7 Nickel zinc and related soft ferrite nanoparticles have been synthesized using
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Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2007.0236 J. Mater. Res., Vol. 22, No. 7, Jul 2007
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chemical solution processes such as coprecipitation,8–10 sol-gel,11 and hydrothermal method.12,13 Mixed iron oxide particles have been synthesized from aqueous metal salt solution by hydrolysis using alkaline hydroxide. Asprecipitated and sol-gel-derived powders have low crystallinity and reveal poor magnetic properties. The asprecipitated powders are heat-treated above 400 °C to improve their magnetic properties.8–11 The uniform dispersion of magnetic particles into polymer matr
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