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Title: Improvement of saturation magnetization of Fe nanoparticles by post-annealing in a hydrogen gas atmosphere

Abstract

Fe nanoparticles (NPs) were synthesized by the thermal decomposition of Fe(CO){sub 5} and then post-annealing in a hydrogen gas atmosphere to produce highly monodisperse Fe NPs with high saturation magnetization (M{sub s}). The as-synthesized pre-anneal Fe NPs had an expanded α-Fe structure and M{sub s} was only 39% of that for bulk Fe because of the low crystallinity and the inclusion of a surfactant. Post-annealing of the Fe NPs in a hydrogen gas atmosphere at 200 °C improved the crystallinity of the Fe NPs from an amorphous-like structure to a body centered cubic (bcc) structure without any lattice expansion. This result indicates that hydrogen gas plays a significant role in improvement of the crystallinity of Fe NPs. Accompanying the improvement in crystallinity, M{sub s} for the Fe NPs increased from 86 to 190 emu/g{sub net} at 300 K, the values of which include the weight of surfactant. This enhanced M{sub s} is almost the same as that of bulk Fe (218 emu/{sub Fe}). It was concluded that the crystallinity has a significant influence on the M{sub s} of the Fe NPs because long-range ordering of the lattice can maintain strong direct exchange interactions between Fe atoms.

Authors:
; ; ;  [1]; ;  [2]
  1. Research Laboratories, DENSO CORPORATION, 500-1, Minamiyama, Komenoki-cho, Nisshin, Aichi 470-0111 (Japan)
  2. Department of Electronic Engineering, Graduate School of Engineering, Tohoku University, 6-6-05 Aza-Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)
Publication Date:
OSTI Identifier:
22410167
Resource Type:
Journal Article
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 117; Journal Issue: 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-8979
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 77 NANOSCIENCE AND NANOTECHNOLOGY; ANNEALING; BCC LATTICES; CARBON MONOXIDE; CRYSTALS; EXCHANGE INTERACTIONS; HYDROGEN; IRON; MAGNETIZATION; NANOPARTICLES; PYROLYSIS; SURFACTANTS

Citation Formats

Kin, Masane, E-mail: masane-kin@denso.co.jp, Tanaka, Masaaki, Hayashi, Yasushi, Hasaegawa, Jun, Kura, Hiroaki, and Ogawa, Tomoyuki. Improvement of saturation magnetization of Fe nanoparticles by post-annealing in a hydrogen gas atmosphere. United States: N. p., 2015. Web. doi:10.1063/1.4919050.
Kin, Masane, E-mail: masane-kin@denso.co.jp, Tanaka, Masaaki, Hayashi, Yasushi, Hasaegawa, Jun, Kura, Hiroaki, & Ogawa, Tomoyuki. Improvement of saturation magnetization of Fe nanoparticles by post-annealing in a hydrogen gas atmosphere. United States. doi:10.1063/1.4919050.
Kin, Masane, E-mail: masane-kin@denso.co.jp, Tanaka, Masaaki, Hayashi, Yasushi, Hasaegawa, Jun, Kura, Hiroaki, and Ogawa, Tomoyuki. Thu . "Improvement of saturation magnetization of Fe nanoparticles by post-annealing in a hydrogen gas atmosphere". United States. doi:10.1063/1.4919050.
@article{osti_22410167,
title = {Improvement of saturation magnetization of Fe nanoparticles by post-annealing in a hydrogen gas atmosphere},
author = {Kin, Masane, E-mail: masane-kin@denso.co.jp and Tanaka, Masaaki and Hayashi, Yasushi and Hasaegawa, Jun and Kura, Hiroaki and Ogawa, Tomoyuki},
abstractNote = {Fe nanoparticles (NPs) were synthesized by the thermal decomposition of Fe(CO){sub 5} and then post-annealing in a hydrogen gas atmosphere to produce highly monodisperse Fe NPs with high saturation magnetization (M{sub s}). The as-synthesized pre-anneal Fe NPs had an expanded α-Fe structure and M{sub s} was only 39% of that for bulk Fe because of the low crystallinity and the inclusion of a surfactant. Post-annealing of the Fe NPs in a hydrogen gas atmosphere at 200 °C improved the crystallinity of the Fe NPs from an amorphous-like structure to a body centered cubic (bcc) structure without any lattice expansion. This result indicates that hydrogen gas plays a significant role in improvement of the crystallinity of Fe NPs. Accompanying the improvement in crystallinity, M{sub s} for the Fe NPs increased from 86 to 190 emu/g{sub net} at 300 K, the values of which include the weight of surfactant. This enhanced M{sub s} is almost the same as that of bulk Fe (218 emu/{sub Fe}). It was concluded that the crystallinity has a significant influence on the M{sub s} of the Fe NPs because long-range ordering of the lattice can maintain strong direct exchange interactions between Fe atoms.},
doi = {10.1063/1.4919050},
journal = {Journal of Applied Physics},
issn = {0021-8979},
number = 17,
volume = 117,
place = {United States},
year = {2015},
month = {5}
}