title: Synthesis, characterization, and magnetic properties of carbon- and boron-oxide-encapsulated iron nanocapsules.
abstract: Carbon- and boron-oxide-encapsulated iron nanocapsules have been synthesized by arc discharge in methane (CH4) and diborane (B2H6) atmospheres respectively. The characterization and magnetic properties of carbon- and boron-oxide-encapsulated iron nanocapsules [abbreviated as Fe(C) and Fe(B) respectively] were investigated and compared. The structure of the Fe(B) nanocapsules is different from that of the Fe(C) nanocapsules. The Fe(C) nanocapsules consist of a crystalline graphite shell and a core of alpha-Fe and/or Fe3C. The Fe(B) nanocapsules consist of an amorphous boron-oxide layer and a core of Fe(B) solid solution, alpha-Fe, gamma-Fe, FeB, and/or Fe3B phases. The saturation magnetizations of both the Fe(C) and the Fe(B) nanocapsules below 300 K decrease monotonically with increasing temperature. The coercivities of the Fe(C) and Fe(B) nanocapsules are almost 2 orders of magnitude higher than that of bulk Fe. The temperature dependence of magnetization at high temperatures indicates the existence of some phase transformations.
authors.affiliation: International Centre for Materials Physics, Institute of Metal Research, Academia Sinica, Shenyang 110016, Peoples' Republic of China.
authors.forename: Z D
authors.initials: ZD
authors.lastname: Zhang
authors.forename: J G
authors.initials: JG
authors.lastname: Zheng
authors.forename: I
authors.initials: I
authors.lastname: Skorvanek
authors.forename: J
authors.initials: J
authors.lastname: Kovac
authors.forename: J L
authors.initials: JL
authors.lastname: Yu
authors.forename: X L
authors.initials: XL
authors.lastname: Dong
authors.forename: Z J
authors.initials: ZJ
authors.lastname: Li
authors.forename: S R
authors.initials: SR
authors.lastname: Jin
authors.forename: X G
authors.initials: XG
authors.lastname: Zhao
authors.forename: W
authors.initials: W
authors.lastname: Liu
mesh_terms: D001894:Borohydrides / Q000737:chemistry; D001896:Boron Compounds / Q000138:chemical synthesis / Q000737:chemistry* / Q000302:isolation & purification; D002244:Carbon / Q000737:chemistry* / Q000302:isolation & purification; D004339:Drug Compounding / Q000379:methods*; D007501:Iron / Q000737:chemistry* / Q000302:isolation & purification; D046911:Macromolecular Substances; D008280:Magnetics; D008697:Methane / Q000737:chemistry; D008854:Microscopy, Electron; D008863:Microspheres; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D001894:Borohydrides; D001896:Boron Compounds; D046911:Macromolecular Substances; C042168:boron oxide; D002244:Carbon; C024731:diborane; D007501:Iron; D008697:Methane