Experimental observations and nucleation and growth theory of polyhedral magnetic ferrite nanoparticles synthesized using an RF plasma torch

Swaminathan, Raja; Willard, M. A.; McHenry, Michael E.

doi:10.1016/j.actamat.2005.10.015

Cited by 57 publications

(24 citation statements)

References 30 publications

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“…Strongly faceted particles of magnetite are uncommon because their surface energy is greater than that of spherical particles. [35] The change in surfacem orphology in this case probably occurs through the partial oxidation of the surface by the phosphate functional groups. [30] The surface oxidation then causes as urfacer earrangementt oamore denselyp acked surface and the formationo ff acetes.…”

Section: Resultsmentioning

confidence: 96%

p‐Phosphonated Calix[n]arene Stabilizes Superparamagnetic Nanoparticles for Nitrate and Phosphate Uptake

et al. 2017

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Section: Resultsmentioning

confidence: 96%

p‐Phosphonated Calix[n]arene Stabilizes Superparamagnetic Nanoparticles for Nitrate and Phosphate Uptake

et al. 2017

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“…29 In the TEM investigations, the Pt nanoparticles in the water phase were moving when they were irradiated by the electron beam in TEM, therefore the high-resolution TEM images are not very clear. But based on the similarity of our TEM images and the Fast Fourier Transform pattern with the results from other publications [29][30][31][32] (Table S2 †) which indicated it is a truncated octahedral, we would like to conclude that our particle is also a truncated octahedral. This multifaceted crystal has atomic steps and terraces which can enhance the activity of a catalyst; 31 hence, the particles which grow for 30 minutes show higher activity.…”

Section: Effect Of the Growing Timementioning

confidence: 91%

A new method to synthesize very active and stable supported metal Pt catalysts: thermo-destabilization of microemulsions

et al. 2012

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A new technique to deposit nanoparticles synthesized in reverse micellar microemulsions onto support material without agglomeration is named thermal destabilization of microemulsion. The multifaceted Pt crystals, mostly truncated octahedra, were produced inside reverse micelles with an average size of 2.5 nm and a narrow size distribution. After deposition, the Pt crystals were found to be well dispersed on the support with an average size of 2.5 nm. After testing with hydrogenation of a-methyl styrene, the produced Pt-catalyst showed higher activity (6 times higher) and stability than commercial ones. The advantages of this synthesis route of nanoparticles include simple operation, and the ease of controlling the size and shape of nanoparticles without using capping agents.

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“…Numerous reports are available on the surface anisotropy of ferrite nanoparticles showing significant change in magnetic properties of these materials. [31][32][33][34] Due to the large surface-to-volume ratio, unusual magnetic behaviors, derived from surface spin disorder, have been observed in mechanically activated NiFe 2 O 4 nanoparticles. 25 particles of single domain exhibit the unusual Hopkinson effect, where magnetization reaches a maximum just below the Curie temperature T c in the presence of a small external magnetic field.…”

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confidence: 99%

Temperature dependence of magnetization and anisotropy in uniaxial NiFe2O4 nanomagnets: Deviation from the Callen-Callen power law

Chatterjee

Ghosh

Chattopadhyay

2014

Journal of Applied Physics

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The thermal variation of magnetic anisotropy (K) and saturation magnetization (MS) for uniaxial nickel ferrite (NiFe2O4) nanomagnets are investigated. Major magnetic hysteresis loops are measured for the sample at temperatures over the range 5–280 K using a vibrating sample magnetometer. The high-field regimes of the hysteresis loops are modeled using the law of approach to saturation, based on the assumption that at sufficiently high field only direct rotation of spin-moment take place, with an additional forced magnetization term that is linear with applied field. The uniaxial anisotropy constant K is calculated from the fitting of the data to the theoretical equation. As temperature increases from 5 K to 280 K, a 49% reduction of K, accompanied by an 85% diminution of MS is observed. Remarkably, K is linearly proportional to MS2.6 in the whole temperature range violating the existing theoretical model by Callen and Callen. The unusual power-law behavior for the NiFe2O4 uniaxial nanomagnets is ascribed to the non-negligible contributions from inter-sublattice pair interactions, Neel surface anisotropy, and higher order anisotropies. A complete realization of the unusual anisotropy-magnetization scaling behavior for nanoscale two-sublattice magnetic materials require a major modification of the existing theory by considering the exact mechanism of each contributions to the effective anisotropy.

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Experimental observations and nucleation and growth theory of polyhedral magnetic ferrite nanoparticles synthesized using an RF plasma torch

Cited by 57 publications

References 30 publications

p‐Phosphonated Calix[n]arene Stabilizes Superparamagnetic Nanoparticles for Nitrate and Phosphate Uptake

p‐Phosphonated Calix[n]arene Stabilizes Superparamagnetic Nanoparticles for Nitrate and Phosphate Uptake

A new method to synthesize very active and stable supported metal Pt catalysts: thermo-destabilization of microemulsions

Temperature dependence of magnetization and anisotropy in uniaxial NiFe2O4 nanomagnets: Deviation from the Callen-Callen power law

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