Mössbauer spectroscopy, superparamagnetism and ferrofluids

Pfannes, H.‐D.; Filho, José Higino Dias; Magalhães-Paniago, R.; López, J. L.; Paniago, R.

doi:10.1590/s0103-97332001000300011

Cited by 13 publications

(6 citation statements)

References 5 publications

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“…To fits on more complexes Mössbauer spectra lineshapes, it's necessary to consider a hyperfine magnetic field distribution (which is a purely statistical approach) or, as is done in the Pfannes-Higino model (PFANNES et al, 1998;PFANNES et al, 2001;FILHO, 2001), a dependency of the magnetic transition temperature and the anisotropy constant on particle diameter (Eqs. 2 and 3) (Fig.…”

Section: Methodsmentioning

confidence: 99%

ON SPIN HAMILTONIAN FITS TO MÖSSBAUER SPECTRA OF NiFe2O4 NANOPARTICLES SYNTHESIZED BY CO-PRECIPITATION

et al. 2020

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Nanocrystalline NiFe2O4 particles prepared by chemical co-precipitation method were studied using magnetic measurements, 57Fe Mössbauer spectroscopy, X-ray diffraction, and transmission electron microscopy. Fits to Mössbauer spectra, in the range of 4.2 K – 300 K, were done using spin hamiltonians to describe both the electronic and nuclear interactions, a model of superparamagnetic relaxation of two levels (spin ½) and stochastic theory, a log-normal particle size distribution function as well as a dependency of the magnetic transition temperature and the anisotropy constant on particle diameter. We have used evolutionary strategies to fit the more complex Mössbauer spectra line shapes. The nanoparticles have an average size of 7 nm and exhibit superparamagnetism at room temperature. The saturation magnetization (Ms) at 4.2 K was determined from M vs. 1/H plots by extrapolating the value of magnetizations to infinite fields, to 24.21 emu/g and coercivity to 3.15 kOe. A magnetic anisotropy energy constant (K) 1.9´105 J/m3, at 4.2 K, were calculated from magnetization measurements. The synthesis, characterization, and functionalization of magnetic nanoparticles is a highly active area of current research located at the interface between materials science, biotechnology, and medicine. Superparamagnetic iron oxides nanoparticles have unique physical properties and have emerged as a new class of diagnostic probes for multimodal tracking and as contrast agents for magnetic resonance imaging (MRI).

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Section: Methodsmentioning

confidence: 99%

ON SPIN HAMILTONIAN FITS TO MÖSSBAUER SPECTRA OF NiFe2O4 NANOPARTICLES SYNTHESIZED BY CO-PRECIPITATION

et al. 2020

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“…49 Among several isotopes which behave according to the Mossbauer effect, 57 Fe is the most common and popular isotope due to its very low energy γ ray and long-lived excited states. 50 Regarding crystallinity, a correlation between Mossbauer parameters (isomer shift and quadrupole splitting) and crystal structure parameters have been investigated via iron ions in silicate minerals. 51 Among several crystal structure parameters of average metal−oxygen distance, volume per oxygen in a unit cell, and polyhedral volume, the correlation between isomer shift and polyhedral volume delimits the shift ranges for tetrahedral, octahedral, and 5-coordinated Fe 3+ ions.…”

Section: ■ Transmission Electron Microscopymentioning

confidence: 99%

Characterization of Magnetic Nanoparticles in Biological Matrices

et al. 2015

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“…Their nanoparticles possess novel magnetic properties. There is a well-defined order in their magnetic ultra fine particles giving them a superparamagnetic behaviour (Kittel 1971;Smit and Wijn 1959;Diatmar and Ahlers 1999;Pfannes et al 2001).…”

Section: Introductionmentioning

confidence: 99%

Ferrofluid thin films as optical gaussmeters proposed for field and magnetic moment sensing

et al. 2011

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Ferrofluids belonging to the series, Ni x Fe 1−x Fe 2 O 4 and Zn x Fe 1−x Fe 2 O 4 , were synthesized using cold co-precipitation. Liquid films of these ferrofluids were prepared by encapsulating the ferrofluids in between two optically smooth and ultrasonically cleaned glass plates. Magnetic field induced laser transmission through these ferrofluid films has been investigated. Magnetic field values can be calibrated in terms of output laser power in the low field region in which the variation is linear. This set up can be used as a cheap optical gaussmeter in the low field regime. Using the same set-up, the saturation magnetization of the sample used can also be calculated with a sample that is pre-characterized. Hence both magnetization of the sample, as well as applied magnetic field can be sensed and calculated with a precalibrated sample.

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Mössbauer spectroscopy, superparamagnetism and ferrofluids

Cited by 13 publications

References 5 publications

ON SPIN HAMILTONIAN FITS TO MÖSSBAUER SPECTRA OF NiFe2O4 NANOPARTICLES SYNTHESIZED BY CO-PRECIPITATION

ON SPIN HAMILTONIAN FITS TO MÖSSBAUER SPECTRA OF NiFe2O4 NANOPARTICLES SYNTHESIZED BY CO-PRECIPITATION

Characterization of Magnetic Nanoparticles in Biological Matrices

Ferrofluid thin films as optical gaussmeters proposed for field and magnetic moment sensing

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