Magnetic properties of ferrites synthesized by low temperature technique
Spinel ferrites have attracted a great deal of attention due to their application potential. These ferrites are attractive as well as from the theoretical point of view. Magnetic properties of the bulk materials differ drastically from the nano-sized mate
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Originally published in the journal Hyperfine Interactions, Volume 184, Nos 1–3, 609–614. DOI: 10.1007/s10751-008-9789-3 © Springer Science + Business Media B.V. 2008
Abstract Spinel ferrites have attracted a great deal of attention due to their application potential. These ferrites are attractive as well as from the theoretical point of view. Magnetic properties of the bulk materials differ drastically from the nanosized materials. Often high temperature sintering is used to synthesize the nanosized materials via solid state reaction route. This method yields bulk ferrites. For nano-sized materials low temperature sintering is required as basic requirement. Copper zinc ferrites have been synthesized by hydrothermal process which employs the decomposition of the hydroxides precursor at about 100◦ C. These samples were characterized by X-ray diffractometer (XRD), vibrating sample magnetometer (VSM),electron paramagnetic resonance (EPR) and Mössbauer spectroscopy. The average particle size in these sintered samples measured by XRD is found to vary from 10 to 150 nm. The XRD shows the formation of single phase spinel structure in all the samples. EPR gives the single asymmetric line at g ∼ 2 with a line width of several hundred gauss. VSM displays non-saturating hysteresis loops and Mössbauer spectra show two sets of sextet related to two distinct sites of iron: site-A and site-B. Keywords Ferrite · Copper zinc ferrite · Nanomaterial · EPR · Mössbauer · Magnetization
1 Introduction The magnetic behavior of bulk magnetic materials is determined and influenced by the formation of domains and domain wall movements. Research into the methods of synthesis and properties of nanoscale materials has exploded over the
P. Chand (B) Department of Physics, Indian Institute of Technology, Kanpur 208016, India e-mail: [email protected]
N. S. Gajbhiye and S. K. Date, ICAME 2007. DOI: 10.1007/978-3-540-78696-2_82
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past decade due to the unique size dependent properties of nanoparticles that often differ considerably from their bulk phase materials [1, 2]. Interpreting the magnetic response of bulk materials is complicated by the fact that domain wall movement can be impeded or pinned by impurities, grain boundaries, etc. in the sample. Hence a direct correlation between the observed magnetic response and the quantum origins of magnetism is not readily achievable. However, if the size of the magnetic material is decreased below a critical length, domain formation is no longer energetically favoured and each particle exists as a single domain [3]. The formation of single domain particles due to particle size reduction in magnetic materials also gives rise to the phenomenon of superparamagnetism. Briefly, superparamagnetism occurs when thermal fluctuations or an applied magnetic field can easily move the magnetic moments of the nano-particles away from the easy axis, the preferred crystallographic axes for the magnetic moment to point along. Each particle behaves like a paramagnetic atom, but with a giant magnetic
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