We have synthesized the bulk form of the superparamagnetic nanocomposites of Fe nanoparticles and activated carbon. Here highly porous feature of activated carbon and magnetic properties of Fe nanoparticles were combined together to form the nanocomposites by mechanical mixing of different proportion of both of them. These nanocomposites are characterized by various characterization techniques like X-ray diffraction (XRD), transmission electron microscopy (TEM), magnetization measurement and Mössbauer spectroscopy. The observed XRD patterns have shown most intense peaks at 2θ = 44.8 degree, which correspond to the (110) plane of the pure Fe in body centered cubic phase. Average particles sizes obtained by TEM imaging are in the range of 20 nm, which are below the required limit for Fe nanoparticles to be in superparamagnetic phase. The superparamagnetic nature of the nanocomposites together with trace amount of the ferromagnetic phase was confirmed by magnetization measurements and Mössbauer spectroscopy. Particles size calculated by the Langavin function fitting of the magnetization vs magnetic field curves are in qualitatively good agreement with the size obtained from TEM imaging.
Morphology and magnetic properties of Fe3O4-alginic acid nanocomposites
研究了Fe 3 O 4/海藻酸纳米复合材料的形貌、结构和磁性能。磁铁矿Fe 3 O 4纳米粒子和海藻酸包覆的纳米粒子表现出非常不同的性质。海藻酸与磁铁矿纳米颗粒表面的化学键合导致表面磁化强度的恢复。另一方面，它也导致了增强的表面自旋无序和非常规的磁化行为观察到的Fe 3 O 4-AA纳米复合材料在低温下。
我们报告的交换偏置（EB）在Au-Fe 3 O 4复合纳米粒子系统，其中一个或多个Fe 3 O 4纳米粒子连接到一个Au种子粒子形成二聚体和集群形态，与集群显示更强的EB相比，二聚体。EB效应的发展是由于在Au-Fe 3 O 4界面中存在应力，这导致在Fe 3 O 4颗粒中产生高度无序的各向异性表面自旋。随着界面应力的消除，电子束效应消失。我们的原子Monte-Carlo研究与实验结果非常吻合。这些结果显示了一种新的途径，调整EB在纳米结构，即可控地创建界面应力，并开辟了通过可控的交换耦合机制，调整生物相容性纳米粒子的各向异性性能的可能性。
Coexistence of Interfacial Stress and Charge Transfer in Graphene Oxide based Magnetic Nanocomposites
在本文中，我们建立了水热合成的钴铁酸盐-氧化石墨烯（CoFe 2 O 4/GO）纳米复合材料中存在的压应力和电荷转移过程。透射电子显微镜（TEM）的结果表明，CoFe 2 O 4纳米粒子的GO片上的装饰。超导量子干涉仪（SQUID）磁强计测量证实了纳米复合材料的磁响应。这些纳米复合材料的光学性能进行了研究，通过拉曼光谱。通过观察氧化石墨烯特征G峰的蓝移来评价该体系中涉及的界面压应力。半峰全宽（FWHM）的增加以及D和G峰的上移是GO片和分散的磁性纳米颗粒之间的电荷转移过程的参与的清楚指示。电荷转移过程的影响是量化的费米能级的这些纳米复合材料的移位。这是使用扫描开尔文探针显微镜（SKPM）从接触表面电势差（CPD）的变化来评价的。CoFe 2 O 4/GO的XRD光谱证实了CoFe 2 O 4纳米颗粒的多晶性质。从XRD峰估计晶格应变与观察到的拉曼位移。
Interplay between Exchange Interaction and Magnetic Shape Anisotropy of ferromagnetic nanoparticles in a non-magnetic matrix for rare-earth-free permanent magnets
Enhanced Thermoelectric ZT in the Tails of the Fermi Distribution via Electron Filtering by Nanoinclusions -- Model Electron Transport in Nanocomposites
我们报告了CoFe 2 O 4/CoFe 2纳米复合材料的实验研究，CoFe 2 O 4/CoFe 2纳米复合材料是由硬磁材料（CoFe 2 O 4）和软磁材料（CoFe 2）形成的纳米结构材料。前驱体材料，钴铁氧体（CoFe 2 O 4），使用传统的化学计量凝胶燃烧法制备。纳米复合材料通过分别在800和900 ℃下在空气和氩气气氛中使用活性炭作为还原剂部分还原前体材料而获得。磁滞回线表明，在一般情况下，制备的纳米复合材料样品显示单一的磁性行为，表明软，硬磁相之间的交换耦合。然而，对于在较高温度下制备的纳米复合材料样品，磁滞测量显示典型的两相磁行为的步骤，这表明存在两个非耦合的磁相。所研究的纳米复合材料呈现出约0.7 kOe的矫顽力（HC），这大大低于钴铁氧体的预期值。高能球磨处理后，纳米复合材料的HC（>440%）和最大能量积（约240%）得到了巨大的增加。
Enhanced nanocomposite susceptibility by field-alignment of superparamagnetic particles
DTU Physics, Technical University of Denmark（丹麦技术大学物理系）；Department of Physics, Norwegian University of Science and Technology（挪威科技大学物理系）；Institute for Energy Security and Environmental Safety, HUN-REN Centre for Energy Research（匈牙利科学院能源研究中心能源安全与环境安全研究所）；MAXIV Laboratory, Lund University（隆德大学MAXIV实验室）；RISE Research Institute of Sweden, Sensor Systems（瑞典RISE研究院传感器系统）；DTU Electro, Technical University of Denmark（丹麦技术大学电气工程系）；DTU Nanolab, Technical University of Denmark（丹麦技术大学纳米实验室）；Department of Physics, University of Modena and Reggio Emilia（摩德纳和雷焦艾米利亚大学物理系）
