Fabrication of Fe Nanoparticle-based Bulk Material with post-annealing

Abstract

The magnetic properties of Fe nanoparticle-based bulk material, which was fabricated with a through post-annealing process under vacuum conditions, were investigated to develop a new Fe-based soft magnetic material. Fe nanoparticles (NPs) retained uniform-size and narrow-size distributions at a post annealing temperature (Ta) of 473K. Their assembly was self organized, which is referred to as nano size periodicity. Soft magnetic properties were obtained at 1.7±0.2 Oe of coercivity at room temperature, and 179 emu/gnet of saturation magnetization was obtained at 5K by using Ta=473 K. Above Ta= 573 K, saturation magnetization decreased and coercivity was increased. High temperature post-annealing above 523 K caused NP growth and the transformation α-Fe to Fe 3 C, which originated from carbon impurities in the surfactant. Thus, the low-temperature post-annealing process plays an important role in achieving high performance soft magnetic properties using Fe NP-based bulk material by desorbing of surfactants without the formation of iron carbide.

Improve of Saturation Magnetization of Fe Nanoparticles by Additive Surfactant with Weak Adsorption Ability

“…Fe ナノ粒子(NPs)は他の磁性ナノ粒子と比べて高い飽和 磁化(σ s )を有している 1,2) ．このため，Fe ナノ粒子の合成と その集合体に関する研究が盛んにおこなわれており，近年 では高 σ s と高透磁率を両立した磁性ナノ粒子型の新規軟磁 性材料や磁性誘電材料への応用に向けた研究がおこなわれ ている 3,4) ．Fe ナノ粒子の作製法として Fe(CO) 5 Fig.3 Reaction time-dependence of particle diameter.…”

Direct Synthesis of Single Crystalline $\alpha$-Fe Nanoparticles With High Saturation Magnetization by Mixed Surfactant

“…Hence, Fe NPs synthesized by thermal decomposition of Fe(CO) and their assembly have been expected for applying to high-performance antenna and soft magnetic materials. However, at present, of the synthesized Fe NPs is 30% smaller than that of -Fe bulk because the NP consists of a low phase that was formed during the rapid growth process and/or partial carbonization [4]- [6]. On the other hand, it is well known that the most stable phase and large grain are formed under slow crystal growth condition.…”