Phase composition and magnetic characteristics of Fe-filled multi-walled carbon nanotubes

Microstructure and magnetism of nanoparticles withγ-Fecore surrounded byα-Feand iron oxide shells

“…The spectrum recorded at 300 K can be satisfactorily described with three different components: ͑i͒ a well-defined sextet with B HF ͑Ϸ33.0 T͒ attributed to the ␣-Fe phase; ͑ii͒ an intense single peak with isomer shift ͑␦ ϳ −0.1 mm s −1 ͒ assigned to paramagnetic ␥-Fe phase 44,45,53 ͑note that the value of the lattice parameter at room temperature, a Ͻ3.6 Å, suggests a nonferromagnetic state for ␥-Fe͒, and ͑iii͒ a quadrupolar doublet plus a broad single line to better describe the baseline both with the same isomer shift ͑ϳ0.38 mm s −1 ͒ typical of some ferric oxide species. The relative proportions are: 43͑2͒%, 28͑2͒%, and 29͑1͒%, respectively.…”

“…Up to now, this ␥-Fe phase was observed in small iron precipitates embedded in a Cu matrix, 38 in FeCu mechanically alloyed compounds, 39,40 in the synthesis of carbon nanotubes, [41][42][43][44][45][46][47][48] or in Fe-NPs and thin films but confined down to a few monolayers of thickness. [49][50][51][52][53][54][55] The magnetism of ␥-Fe phase depends strongly on the Fe-Fe interatomic distances 56 although both the morphology of the sample and the particle size could play an important role.…”

Enhanced saturation magnetization in buckypaper-films of thin walled carbon nanostructures filled with Fe3C, FeCo, FeNi, CoNi, Co and Ni crystals: the key role of Cl

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] In particular large coercivities have been achieved by encapsulating small particles with a size in the order of a single magnetic domain inside multiwalled CNTs through sublimation and pyrolysis of ferrocene in conventional chemical vapour deposition (CVD) systems. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] In particular large coercivities have been achieved by encapsulating small particles with a size in the order of a single magnetic domain inside multiwalled CNTs through sublimation and pyrolysis of ferrocene in conventional chemical vapour deposition (CVD) systems.…”

Influence of Underlayer on Growth of Carbon Nanotubes Filled with Iron Nanowires

“…Several studies have addressed Fe@CNTs synthesized by thermal chemical vapor deposition (T-CVD), along with their growth characteristics and magnetic properties [9][10][11][12][13][14][15][16][17][18][19][20][21]. In our previous study, the Fe@CNT growth morphology strongly relied on growth temperature and the amount of precursor used in the T-CVD reactor and impacted magnetic properties; the coercivity exceeded 127.6 kA/m (1.6 kOe) because of the crystal structure of the Fe@CNT, which is remarkably valuable considering that iron is a soft magnetic material [22].…”