title: Low-Energy Bead-Mill Dispersion of Agglomerated Core-Shell α-Fe/Al₂O₃ and α″-Fe₁₆N₂/Al₂O₃ Ferromagnetic Nanoparticles in Toluene.
abstract: Magnetic materials such as α″-Fe16N2 and α-Fe, which have the largest magnetic moment as hard and soft magnetic materials, are difficult to produce as single domain magnetic nanoparticles (MNPs) because of quasistable state and high reactivity, respectively. The present work reports dispersion of agglomerated plasma-synthesized core-shell α″-Fe16N2/Al2O3 and α-Fe/Al2O3 in toluene by a new bead-mill with very fine beads to prepare single domain MNPs. As a result, optimization of the experimental conditions (bead size, rotation speed, and dispersion time) enables the break-up of agglomerated particles into primary particles without destroying the particle structure. Slight deviation from the optimum conditions, i.e., lower or higher dispersion energy, gives undispersed or broken particles due to fragile core-shell structure against stress or impact force of beads. The dispersibility of α″-Fe16N2/Al2O3 is more restricted than that of α-Fe/Al2O3, because of the preparation conditions. Especially for α″-Fe16N2/Al2O3, no change on crystallinity (98% α″-Fe16N2) or magnetization saturation after dispersion was observed, showing that this method is appropriate to disperse α″-Fe16N2/Al2O3 MNPs. A different magnetic hysteresis behavior is observed for well-dispersed α″-Fe16N2/Al2O3 MNPs, and the magnetic coercivity of these NPs is constricted when the magnetic field close to zero due to magnetic dipole coupling among dispersed α″-Fe16N2 MNPs.
authors.affiliation: †Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima, 739-8527, Japan.
authors.forename: Rizka
authors.initials: R
authors.lastname: Zulhijah
authors.affiliation: †Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima, 739-8527, Japan.|‡Program Studi Teknik Fisika, Fakultas Teknik Elektro, Telkom University, Jl. Telekomunikasi Terusan Buah Batu, Bandung, 40257, Indonesia.
authors.forename: Asep
authors.initials: A
authors.lastname: Suhendi
authors.affiliation: †Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima, 739-8527, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Yoshimi
authors.affiliation: †Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima, 739-8527, Japan.
authors.forename: Christina Wahyu
authors.initials: CW
authors.lastname: Kartikowati
authors.affiliation: †Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima, 739-8527, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Ogi
authors.affiliation: †Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima, 739-8527, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Iwaki
authors.affiliation: †Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima, 739-8527, Japan.
authors.forename: Kikuo
authors.initials: K
authors.lastname: Okuyama
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties; D014050:Toluene / Q000737:chemistry*
chemical_list: D058185:Magnetite Nanoparticles; D014050:Toluene; D007501:Iron; D000537:Aluminum Oxide; D009584:Nitrogen