Magnetic study of Mg_0.95Mn_0.05Fe₂O₄ ferrite nanoparticles

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• 作者：S.K. Sharma ; Ravi Kumar ; Shalendra Kumar ; V.V. Siva Kumar ; M. Knobel ; V.R. Reddy ; A. Banerjee ; M. Singh
• 关键词：A. Ferrites ; B. Nanocrystalline materials ; C. Mö ; ssbauer spectroscopy ; D. Magnetization
• 刊名：Solid State Communications
• 出版年：2007
• 期刊代码：101_00381098
• 类别：ms
• 出版时间：January 2007
• 卷：141
• 期：4
• 页码：203-208
• 文件大小：585 K

摘要

The magnetic properties of Mg_0.95Mn_0.05Fe₂O₄ ferrite samples with an average particle size of 6.0±0.6 nm have been studied using X-ray diffraction, Mössbauer spectroscopy, dc magnetization and frequency dependent real me="mml11">method=retrieve&_udi=B6TVW-4M813WX-5&_mathId=mml11&_user=10&_cdi=5545&_rdoc=9&_acct=C000050221&_version=1&_userid=10&md5=08099be3c6dbb0586dc43011a03a556b" title="Click to view the MathML source">χ^′(T) and imaginary me="mml12">method=retrieve&_udi=B6TVW-4M813WX-5&_mathId=mml12&_user=10&_cdi=5545&_rdoc=9&_acct=C000050221&_version=1&_userid=10&md5=f2dd57cecfd6aaf48c270c60811af819" title="Click to view the MathML source">χ^″(T) parts of ac susceptibility measurements. A magnetic transition to an ordered state is observed at about 195 K from Mössbauer measurements. The zero-field-cooled (ZFC) and field-cooled (FC) magnetization have been recorded at low field and show the typical behavior of a small particle system. The ZFC curve displays a broad maximum at me="mml13">, a temperature which depends upon the distribution of particle volumes in the sample. The FC curve was nearly flat below me="mml14">, as compared with monotonically increasing characteristics of non-interacting superparamagnetic systems indicating the existence of strong interactions among the nanoparticles. A frequency-dependent peak observed in me="mml15">method=retrieve&_udi=B6TVW-4M813WX-5&_mathId=mml15&_user=10&_cdi=5545&_rdoc=9&_acct=C000050221&_version=1&_userid=10&md5=9c9f3b9ad7d0450338070931f1615146" title="Click to view the MathML source">χ^′(T) is well described by Vogel–Fulcher law, yielding a relaxation time me="mml16"> and an interaction parameter me="mml17">. Such values show the strong interactions and rule out the possibility of spin-glass (SG) features among the nanoparticle system. On the other hand fitting with the Néel–Brown model and the power law yields an unphysical large value of me="mml18">method=retrieve&_udi=B6TVW-4M813WX-5&_mathId=mml18&_user=10&_cdi=5545&_rdoc=9&_acct=C000050221&_version=1&_userid=10&md5=7a1e4a73682a4c9a28e29d2a62fbbed2" title="Click to view the MathML source">τ₀ (6×10⁻⁶⁹ and 1.2×10⁻²² s respectively).