Tuning dipolar magnetic interactions by controlling individual silica coating of iron oxide nanoparticles

Autor(es)

Rivas Rojas, P. C. ^[1] ; Tancredi, P. ^[1] ; Moscoso Londono, O. ^{[2, 3]} ; Knobel, M. ^[2] ; Socolovsky, L. M. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Buenos Aires, CONICET, Fac Ingn, Lab Solidos Amorfos, Inst Tecnol & Ciencias Ingn Hilario Fernandez Lon, Buenos Aires, DF - Argentina

^[2] Univ Estadual Campinas, Inst Fis Gleb Wataghin, Lab Mat & Baixas Temp, Campinas, SP - Brazil

^[3] Univ Autonoma Manizales, Antigua Estn Ferrocarril, Manizales - Colombia

• Tipo de documento: Artigo Científico
• Fonte: Journal of Magnetism and Magnetic Materials; v. 451, p. 688-696, APR 1 2018.
• Citações Web of Science: 6

Resumo

Single and fixed size core, core-shell nanoparticles of iron oxides coated with a silica layer of tunable thickness were prepared by chemical routes, aiming to generate a frame of study of magnetic nanoparticles with controlled dipolar interactions. The batch of iron oxides nanoparticles of 4.5 nm radii, were employed as cores for all the coated samples. The latter was obtained via thermal decomposition of organic precursors, resulting on nanoparticles covered with an organic layer that was subsequently used to promote the ligand exchange in the inverse microemulsion process, employed to coat each nanoparticle with silica. The amount of precursor and times of reaction was varied to obtain different silica shell thicknesses, ranging from 0.5 nm to 19 nm. The formation of the desired structures was corroborated by TEM and SAXS measurements, the core single-phase spinel structure was confirmed by XRD, and superparamagnetic features with gradual change related to dipolar interaction effects were obtained by the study of the applied field and temperature dependence of the magnetization. To illustrate that dipolar interactions are consistently controlled, the main magnetic properties are presented and analyzed as a function of center to center minimum distance between the magnetic cores. (C) 2017 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 14/26672-8 - Efeitos de interface e superfície em nanoheteroestruturas magnético-metálicas
• Beneficiário: Oscar Moscoso Londono
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado