Artículo
Determination of the effective anisotropy of magnetite/maghemite nanoparticles from Mössbauer effect spectra
Fecha de publicación:
06/2022
Editorial:
IOP Publishing
Revista:
Journal of Physics D: Applied Physics
ISSN:
0022-3727
Idioma:
Inglés
Tipo de recurso:
Artículo publicado
Clasificación temática:
Resumen
The stoichiometry and the effective anisotropy constant (K eff ) of several samples of iron-oxide nanoparticles with sizes between 12 and 51 nm, showing spheroidal and cubic shapes, were studied by means of Mössbauer spectroscopy at room temperature (RT). Mössbauer spectra were analyzed and fitted considering two magnetically split subspectra due to Fe3+ and Fe2.5+ ions in tetrahedral and octahedral sites of a non-stoichiometric magnetite, respectively. In order to take into account the collective fluctuations of the NPs magnetic moments, the measured Mössbauer spectra were fitted including a distribution of the hyperfine interactions associated with the NPs volume (V) distribution. To determine the K eff value, a direct comparison between the size distribution obtained from structural characterization techniques and the KeffV product obtained from Mössbauer spectra fitting was made. In this regard, the K eff value was determined as the one that maximizes the coincidence between the mean NPs sizes obtained by both methods. Finally, an overall surface anisotropy constant K s value was obtained by means of a linear relation between the mean NP size, the experimentally determined K eff and a weighted arithmetic mean magnetic anisotropy related with the bulk magnetite and maghemite anisotropy constants at RT. An evident relation between the KeffV values through the parameter λ=KeffV/kBT and the magnetite/maghemite fraction in each sample was also observed.
Palabras clave:
EFFECTIVE ANISOTROPY
,
IRON OXIDE NANOPARTICLES
,
SURFACE ANISOTROPY
Archivos asociados
Licencia
Identificadores
Colecciones
Articulos(IFLP)
Articulos de INST.DE FISICA LA PLATA
Articulos de INST.DE FISICA LA PLATA
Citación
Orozco Henao, Juan Manuel; Muraca, D.; Sanchez, Francisco Homero; Mendoza Zélis, Pedro; Determination of the effective anisotropy of magnetite/maghemite nanoparticles from Mössbauer effect spectra; IOP Publishing; Journal of Physics D: Applied Physics; 55; 33; 6-2022; 1-10
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