Effects of Zn Substitution in the Magnetic and Morphological Properties of Fe-Oxide-Based Core-Shell Nanoparticles Produced in a Single Chemical Synthesis

Author(s):Show less -

Lohr, Javier ^[1] ; Aparecida de Almeida, Adriele ^{[1, 2]} ; Sergio Moreno, M. ^[1] ; Troiani, Horacio ^{[2, 3]} ; Goya, Gerardo F. ^{[4, 5, 6]} ; Torres Molina, Teobaldo Enrique ^{[4, 6]} ; Fernandez-Pacheco, Rodrigo ^{[4, 6]} ; Winkler, Elfin L. ^{[1, 2]} ; Vasquez Mansilla, Marcelo ^[1] ; Cohen, Renato ^[7] ; Nagamine, Luiz C. C. M. ^[7] ; Rodriguez, Luis M. ^[1] ; Fregenal, Daniel E. ^[1] ; Zysler, Roberto D. ^{[1, 2]} ; Lima, Jr., Enio ^[1]

Affiliation

^[1] CNEA, CONICET, Ctr Atom Bariloche, Inst Nanociencia & Nanotecnol, Av Bustillo 9500, RA-8400 San Carlos De Bariloche, Rio Negro - Argentina

^[2] Univ Nacl Cuyo, CNEA, Inst Balseiro, Av Bustillo 9500, RA-8400 San Carlos De Bariloche, Rio Negro - Argentina

^[3] Univ Zaragoza, CONICET, CAB, Lab Caracterizac Mat & Oxidos Noestequiometr Gere, E-50009 Zaragoza - Spain

^[4] Univ Zaragoza, INA, Zaragoza 50018 - Spain

^[5] Univ Zaragoza, Fac Ciencias, Dept Fis Mat Condensada, E-50009 Zaragoza - Spain

^[6] Univ Zaragoza, LMA, C Mariano Esquillor S-N, Zaragoza 50018 - Spain

^[7] Univ Sao Paulo, Inst Fis, BR-05508090 Sao Paulo - Brazil

• Document type: Journal article
• Source: Journal of Physical Chemistry C; v. 123, n. 2, p. 1444-1453, JAN 17 2019.
• Web of Science Citations: 1

Abstract

Magnetic, compositional, and morphological properties of Zn-Fe-oxide core-shell bimagnetic nano particles were studied for three samples with 0.00, 0.06, and 0.10 Zn/Fe ratios, as obtained from particle-induced X-ray emission analysis. The bimagnetic nano-particles were produced in a one-step synthesis by the thermal decomposition of the respective acetylacetonates. The nanoparticles present an average particle size between 25 and 30 nm as inferred from transmission electron microscopy (TEM). High-resolution TEM images clearly show core-shell morphology for the particles in all samples. The core is composed by an antiferromagnetic (AFM) phase with a Wustite (Fe1-yO) structure, whereas the shell is composed by a ZnxFe3-xO4 ferrimagnetic (FiM) spinet phase. Despite the low solubility of Zn in the Wustite, electron energy-loss spectroscopy analysis indicates that Zn is distributed almost homogeneously in the whole nanoparticle. This result gives information on the formation mechanisms of the particle, indicating that the Wustite is formed first, and the superficial oxidation results in the FiM ferrite phase with similar Zn concentration than the core. Magnetization and in-field Mossbauer spectroscopy of the Zn-richest nanoparticles indicate that the AFM phase is strongly coupled to the FiM structure of the ferrite shell, resulting in a bias field (H-EB) appearing below T-N(FeO), with H-EB values that depend on the core-shell relative proportion. Magnetic characterization also indicates a strong magnetic frustration for the samples with higher Zn concentration, even at low temperatures. (AU)

• FAPESP's process: 16/21371-5 - Structural, magnetic and hyperfine properties of nanoparticles of ferrites (MxFe3-xO4, M=Co, Ni, Cu or Zn) and In-Sn-O (ITO) doped with transition metals and rare-earth elements: Potential applications in hyperthermia and gas sensors
• Grantee: Luiz Carlos Camargo Miranda Nagamine
• Support type: Regular Research Grants