Magnetic Nanoparticles in Borate Glasses: Identification and Sizing
Langue
en
Communication dans un congrès
Ce document a été publié dans
2014-05-22, Bran. 2014p. 95-104
Résumé en anglais
Heat treatment of borate glasses co-doped with low contents of iron and larger radius elements: Dy, Tb, Gd, Ho, Er, Y and Bi results in formation of magnetic nanoparticles, radically changing their physical properties. ...Lire la suite >
Heat treatment of borate glasses co-doped with low contents of iron and larger radius elements: Dy, Tb, Gd, Ho, Er, Y and Bi results in formation of magnetic nanoparticles, radically changing their physical properties. Transmission electron microscopy and synchrotron radiation-based techniques: XRD, EXAFS, XANES and SAXS, show a broad distribution of nanoparticle sizes with characteristic depending on the treatment regime; a crystalline structure of these nanoparticles is detected in heat treated samples. Magnetic circular dichroism (MCD) studies of samples subjected to heat treatment as well as of maghemite, magnetite and iron garnet allow to unambiguously assigning the nanoparticle structure to maghemite. Different features observed in the MCD spectra are related to different electron transitions in Fe3+ ions gathered in the nanoparticles. Variable-temperature electron magnetic resonance (EMR) studies confirm the formation of magnetic nanoparticles and the identification of their nature. Computer simulations of the EMR spectra corroborate the broad distribution of nanoparticle sizes found by “direct” techniques.< Réduire
Mots clés en anglais
Nanoparticles
Glass
Iron
Heat treatment
Ions
Magnetic resonance
Magnetic hysteresis
Origine
Importé de halUnités de recherche