Role of interparticle interactions on the magnetic behavior of Mg0.95Mn0.05Fe2O4 ferrite nanoparticles
Role of interparticle interactions on the magnetic behavior of Mg0.95Mn0.05Fe2O4 ferrite nanoparticles
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DOI：
10.1088/0953-8984/20/23/235214
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发表时间：
2008-05
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影响因子：
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通讯作者：
S. Sharma;Ravi Kumar;Shalendra Kumar;M. Knobel;C. Meneses;V. S. Siva Kumar;V. Reddy;M. Singh;C. G. Lee
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文献类型：
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作者：
S. Sharma;Ravi Kumar;Shalendra Kumar;M. Knobel;C. Meneses;V. S. Siva Kumar;V. Reddy;M. Singh;C. G. Lee
本文详细研究了用高能球磨法制备的具有相同粒度分布(5.1 nm和6.0±0.6 nm)的尖晶石型铁氧体纳米颗粒体系的静态和动态磁行为。用X射线衍射、穆斯堡尔谱、直流磁化强度和交流磁化率的实部χ‘(T)和虚部χ’(T)对样品进行了表征。零场冷(ZFC)和场冷(FC)磁化强度在低场下被记录下来，并且在185±5K以上表现出典型的超顺磁性粒子的行为，这进一步得到了随温度变化的穆斯堡尔测量的支持。根据ZFC磁化强度和穆斯堡尔数据计算出的阻塞温度几乎是相似的，这一事实清楚地表明了这些纳米粒子系统之间的颗粒间相互作用。这进一步得到FC磁化曲线的支持，与非相互作用的超顺磁性粒子的单调增加的行为特征相比，FC磁化曲线在一定的温度(小于阻断温度)下几乎是平坦的。在交流磁化率测量的实部χ‘(T)和虚部χ’(T)中，观察到阻断温度随频率的增加而移动。对结果的分析表明，数据符合Vogel-Fulcher定律，而使用Neel-Brown定律和幂定律的试验是无效的。讨论了磁粒间相互作用对磁行为的影响，即超顺磁弛豫时间和磁各向异性。
We present here a detailed investigation of the static and dynamic magnetic behavior of a Mg0.95Mn0.05Fe2O4 spinel ferrite nanoparticle system synthesized by high-energy ball milling of almost identical particle size distributions (, 5.1 and 6.0 ± 0.6 nm). The samples were characterized by using x-ray diffraction, Mössbauer spectroscopy, dc magnetization and frequency dependent real χ′(T) and imaginary χ′′(T) parts of ac susceptibility measurements. The zero-field-cooled (ZFC) and field-cooled (FC) magnetization have been recorded in a low field and show a behavior typical of superparamagnetic particles above a temperature of 185 ± 5 K, which is further supported from the temperature dependent Mössbauer measurements. The fact that the blocking temperature calculated from the ZFC magnetization and Mössbauer data are almost similar gives a clear indication of the interparticle interactions among these nanoparticle systems. This is further supported from the FC magnetization curves, which are almost flat below a certain temperature (less than the blocking temperature), as compared with the monotonically increasing behavior characteristics of non-interacting superparamagnetic particles. A shift of the blocking temperature with increasing frequency was observed in the real χ′(T) and imaginary χ′′(T) parts of the ac susceptibility measurements. The analysis of the results shows that the data fit well with the Vogel–Fulcher law, whereas trials using the Neel–Brown and power law are unproductive. The role of magnetic interparticle interactions on the magnetic behavior, namely superparamagnetic relaxation time and magnetic anisotropy, are discussed.