Rajesh P, Sellaiyan S, Uedono A, Arun T, Joseyphus R Justin
Magnetic Materials Laboratory, Department of Physics, National Institute of Technology, Tiruchirappalli, 620015, India.
Division of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki, 305-8573, Japan.
Sci Rep. 2018 Jun 27;8(1):9764. doi: 10.1038/s41598-018-27949-2.
Equiatomic flower-like FeCo magnetic nanoparticles are synthesized through a modified one-pot polyol technique. The as-prepared samples are annealed at 700 and 800 °C under reducing atmosphere. The saturation magnetization and coercivity of the flower-like FeCo are found to be 198 (1) emu/g and 243 (10) Oe respectively. The magnetic properties of FeCo approach the bulk behavior with annealing. Positron lifetime studies on the chemically synthesized equiatomic FeCo magnetic nanoparticles with flower-like morphology are reported and compared with Fe, Co and FeCo annealed at various temperatures. The FeCo is characterized by different lifetime components corresponding to positron annihilation events in vacancies and various open volume defects due to their unique morphology. The studies suggest defects arising out of cluster vacancies and interpetal gap that reduce on annealing. The average pore size obtained from positron annihilation studies closely matches with the interpetal distance obtained from the electron microscopic analysis for the flower-like FeCo.
通过改进的一锅多元醇技术合成了等原子花状FeCo磁性纳米颗粒。将制备好的样品在还原气氛下于700和800°C退火。发现花状FeCo的饱和磁化强度和矫顽力分别为198(1)emu/g和243(10)Oe。随着退火，FeCo的磁性接近体相行为。报道了对具有花状形态的化学合成等原子FeCo磁性纳米颗粒的正电子寿命研究，并与在不同温度下退火的Fe、Co和FeCo进行了比较。由于其独特的形态，FeCo的特征在于对应于空位中正电子湮灭事件以及各种开放体积缺陷的不同寿命成分。研究表明，团簇空位和花瓣间隙产生的缺陷在退火时会减少。从正电子湮灭研究获得的平均孔径与从花状FeCo的电子显微镜分析获得的花瓣间距密切匹配。
