Karlsruher Institut für Technologie, Institut für Nanotechnologie, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany ; Institute of Solid State Physics, Russian Academy of Sciences, Ac. Ossipyan str. 2, 142432 Chernogolovka, Russia ; Max-Planck-Institut für Intelligente Systeme, Heisenbergstrasse 3, 70569 Stuttgart, Germany ; National University for Research and Technology "MISiS", Leninsky prospect 4, 119991 Moscow, Russia.
Beilstein J Nanotechnol. 2013 Jun 13;4:361-9. doi: 10.3762/bjnano.4.42. Print 2013.
The influence of the grain boundary (GB) specific area s GB on the appearance of ferromagnetism in Fe-doped ZnO has been analysed. A review of numerous research contributions from the literature on the origin of the ferromagnetic behaviour of Fe-doped ZnO is given. An empirical correlation has been found that the value of the specific grain boundary area s GB is the main factor controlling such behaviour. The Fe-doped ZnO becomes ferromagnetic only if it contains enough GBs, i.e., if s GB is higher than a certain threshold value s th = 5 × 10(4) m(2)/m(3). It corresponds to the effective grain size of about 40 μm assuming a full, dense material and equiaxial grains. Magnetic properties of ZnO dense nanograined thin films doped with iron (0 to 40 atom %) have been investigated. The films were deposited by using the wet chemistry "liquid ceramics" method. The samples demonstrate ferromagnetic behaviour with J s up to 0.10 emu/g (0.025 μB/f.u.ZnO) and coercivity H c ≈ 0.03 T. Saturation magnetisation depends nonmonotonically on the Fe concentration. The dependence on Fe content can be explained by the changes in the structure and contiguity of a ferromagnetic "grain boundary foam" responsible for the magnetic properties of pure and doped ZnO.
已经分析了晶界（GB）比表面积 sGB 对 Fe 掺杂 ZnO 中出现铁磁性的影响。综述了大量关于 Fe 掺杂 ZnO 铁磁行为起源的文献研究贡献。发现了一个经验相关性，即比表面积 sGB 是控制这种行为的主要因素。只有当 Fe 掺杂 ZnO 含有足够的晶界时，即 sGB 高于某个阈值 s th = 5 × 10(4) m(2)/m(3) 时，它才会表现出铁磁性。这对应于有效晶粒尺寸约为 40 μm，假设为完全致密的材料和等轴晶粒。研究了铁（0 至 40 原子%）掺杂 ZnO 致密纳米晶薄膜的磁性。使用湿化学“液体陶瓷”方法沉积了这些薄膜。这些样品表现出铁磁性，饱和磁化强度 Js 高达 0.10 emu/g（0.025 μB/f.u.ZnO），矫顽力 Hc ≈ 0.03 T。饱和磁化强度随 Fe 浓度的变化呈非单调变化。对 Fe 含量的依赖性可以用负责纯 ZnO 和掺杂 ZnO 磁性能的铁磁“晶界泡沫”的结构和连续性变化来解释。
