Enhanced room temperature ferromagnetism in antiferromagnetic NiO nanoparticles
Enhanced room temperature ferromagnetism in antiferromagnetic NiO nanoparticles
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DOI：
10.1063/1.4928426
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发表时间：
2015-08
期刊：
影响因子：
1.6
通讯作者：
P. Ravikumar;B. Kisan;A. Perumal
中科院分区：
文献类型：
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作者：
P. Ravikumar;B. Kisan;A. Perumal
我们报告的结构，振动，共振和磁性的纳米NiO粉末的球磨过程中制备的不同的球磨速度下的30小时的研磨系统的调查。结构特性表明，纯NiO和球磨NiO粉末均呈现面心立方结构，但随着球磨速度的增加，应变显著增加，平均晶粒尺寸沿着减小至11 nm左右。振动性质表明，由于尺寸减小，单声子纵光学（LO）带的强度增强，双磁振子带的强度消失。此外，由于尺寸效应和表面弛豫，双声子本振带出现红移。纯NiO粉体具有反铁磁性质，经粒径减小后转变为感生铁磁。室温下的平均磁化强度随晶粒尺寸的减小而增大，最大磁矩为0.016 μB/f. u。在12千欧的外加电场和COE...
We report systematic investigations of structural, vibrational, resonance and magnetic properties of nanoscale NiO powders prepared by ball milling process under different milling speeds for 30 hours of milling. Structural properties revealed that both pure NiO and as-milled NiO powders exhibit face centered cubic structure, but average crystallite size decreases to around 11 nm along with significant increase in strain with increasing milling speed. Vibrational properties show the enhancement in the intensity of one-phonon longitudinal optical (LO) band and disappearance of two-magnon band due to size reduction. In addition, two-phonon LO band exhibits red shift due to size-induced phonon confinement effect and surface relaxation. Pure NiO powder exhibit antiferromagnetic nature, which transforms into induced ferromagnetic after size reduction. The average magnetization at room temperature increases with decreasing the crystallite size and a maximum moment of 0.016 μB/f.u. at 12 kOe applied field and coe...