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Tuning the structure and magnetic behavior of Ni?Ir-based nanoparticles in ionic liquids

Abstract: We report on a simple preparation of extremely small diameter (ca. 2 nm) Ni?Ir-based NPs using Ni(COD)2 and [Ir(COD)OCH3]2 in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIm·NTf2). The prepared NPs had either core?shell-like or alloy-like structures with the presence of Ni,Ir-oxides, depending on the synthetic approach. X-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), extended X-ray absorption fine structure (EXAFS), and magnetic measurements are combined to describe the influence of nanostructure on the magnetic behavior of these nanosystems. The present findings reveal that the alloy NPs display a disordered magnetic state, similar to a spin glass (SG)-like system (Tf = 7.2 K). Core?shell NPs are formed by a magnetically blocked/unblocked core with a magnetically disordered shell as deduced from the two magnetic responses peaking at TB = 75 K and Tf = 5.8 K. Coupling at the core?shell interface leads to an exchange bias revealed at low temperature as horizontal shifts in the hysteresis loops of 0.12 kOe at 2 K.

 Autoría: Da Silva K., Bernardi F., Abarca G., Baptista D., Leite Santos M., Fernández Barquín L., Dupont J., De Pedro I.,

 Fuente: Phys. Chem. Chem. Phys., 2018,20, 10247-10257

 Editorial: Royal Society of Chemistry

 Fecha de publicación: 13/03/2018

 Nº de páginas: 12

 Tipo de publicación: Artículo de Revista

 DOI: 10.1039/c8cp00164b

 ISSN: 1463-9076,1463-9084

 Proyecto español: MAT2014-55049-C2-R

 Url de la publicación: https://doi.org/10.1039/c8cp00164b

Autoría

SILVA, KÁCRIS I. M. DA

BERNARDI, FABIENO

ABARCA, GABRIEL

BAPTISTA, DANIEL L.

LEITE SANTOS, MARCOS

DUPONT, JAIRTON