Size dependence of the magnetic and hyperfine properties of nanostructured hematite (α-Fe 2 O 3 ) powders prepared by the ball milling technique

André-Filho, J.; Félix, Lizbet León; Coaquira, J. A. H.; Garg, V. K.; Oliveira, A. C.

doi:10.1007/s10751-013-0850-5

Cited by 9 publications

(2 citation statements)

References 15 publications

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“…Moreover, two distinct trends emerge from the analysis of hysteresis loops recorded at 4 K and point out the effects of reduction on our systems, as displayed Figure 5b and summarized in Table 1. Only negligible variations can be observed when comparing the coercivity and remanence values (H C and M R ) of FeO_800 and FeO_25000, which are both consistent with the formation of Fe 3 O 4 NPs around 20 nm in size [32], while the FeO_nopei sample presents dramatically different values, with a strongly enhanced coercivity and a very low remanence that indicate a non-negligible presence of small-sized hematite domains [33,34]. The saturation magnetization M SAT , on the other hand, shows a linear trend from FeO_800 to the FeO_25000 and FeO_nopei samples, with M SAT values of 83 emu/g, 66 emu/g, and 11 emu/g, respectively.…”

Section: Characterization Of Iron Oxide Nanostructuressupporting

confidence: 52%

Synthesizing Iron Oxide Nanostructures: The Polyethylenenemine (PEI) Role

et al. 2017

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Controlled synthesis of anisotropic iron oxide nanoparticles is a challenge in the field of nanomaterial research that requires an extreme attention to detail. In particular, following up a previous work showcasing the synthesis of magnetite nanorods (NRs) using a two-step approach that made use of polyethylenenemine (PEI) as a capping ligand to synthesize intermediate β-FeOOH NRs, we studied the effect and influence of the capping ligand on the formation of β-FeOOH NRs. By comparing the results reported in the literature with those we obtained from syntheses performed (1) in the absence of PEI or (2) by using PEIs with different molecular weight, we showed how the choice of different PEIs determines the aspect ratio and the structural stability of the β-FeOOH NRs and how this affects the final products. For this purpose, a combination of XRD, HRTEM, and direct current superconducting quantum interference device (DC SQUID) magnetometry was used to identify the phases formed in the final products and study their morphostructural features and related magnetic behavior.

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Section: Characterization Of Iron Oxide Nanostructuressupporting

confidence: 52%

Synthesizing Iron Oxide Nanostructures: The Polyethylenenemine (PEI) Role

et al. 2017

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“…This observation possibly implies the presence of interfacial structural disorder and the formation of oxygen vacancies in the recycled α-Fe 2 O 3 nanoparticles. This is in agreement with a previous study of commercial α-Fe 2 O 3 nanoparticles prepared with the ball milling technique [17].…”

Section: Resultssupporting

confidence: 93%

Enhancement of Complex Permittivity and Attenuation Properties of Recycled Hematite (α-Fe2O3) Using Nanoparticles Prepared via Ball Milling Technique

et al. 2019

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The purpose of this study was to synthesize high-quality recycled α-Fe2O3 to improve its complex permittivity properties by reducing the particles to nanosize through high energy ball milling. Complex permittivity and permeability characterizations of the particles were performed using open-ended coaxial and rectangular waveguide techniques and a vector network analyzer. The attenuation characteristics of the particles were analyzed with finite element method (FEM) simulations of the transmission coefficients and electric field distributions using microstrip model geometry. All measurements and simulations were conducted in the 8–12 GHz range. The average nanoparticle sizes obtained after 8, 10 and 12 h of milling were 21.5, 18, and 16.2 nm, respectively, from an initial particle size of 1.73 µm. The real and imaginary parts of permittivity increased with reduced particle size and reached maximum values of 12.111 and 0.467 at 8 GHz, from initial values of 7.617 and 0.175, respectively, when the particle sizes were reduced from 1.73 µm to 16.2 nm. Complex permeability increased with reduced particle size while the enhanced absorption properties exhibited by the nanoparticles in the simulations confirmed their ability to attenuate microwaves in the X-band frequency range.

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