Magnetic ZnFe2O4 nanoferrites studied by X-ray magnetic circular dichroism and Mössbauer spectroscopy

Cationic exchange in nanosizedZnFe2O4spinel revealed by experimental and simulated near-edge absorption structure

“…Atomic absorption spectrometry showed that the initial Zn:Fe ratio of 1:2 was unaltered by milling. Mössbauer spectra recorded at 4.2 K showed that Fe 3+ ions occupy both A and B magnetic sublattices [12]. Further, we observed that the relative area ratio site(A):site[B] doubles from 2ZF to 2ZF10h, indicating a milling-induced transference of iron ions from B to A-sites.…”

“…Previously [12], X-ray diffraction studies showed that all of the samples are of single phase ZnFe 2 O 4 cubic spinel. No amorphous components were detected.…”

“…Iron (III) occupancy of both A and B-sites in nanocrystalline ZnFe 2 O 4 has been extensively proved by Mössbauer spectroscopy [1,2,6,7,8], nuclear magnetic resonance [5], neutron diffraction [3], x-ray absorption [9,10,11,12], and indirectly throughout magnetic measurements [2,3,4,13,14]. To a much lesser extend, Extended X-ray Absorption Fine Structure (EXAFS) studies at Zn K-edge suggest that Zn ions are transferred from its equilibrium position (sites A) to B-sites when the particle size decreases [9,10,11].…”

Dynamic magnetic behavior of cluster-glass ZnFe2O4 nanosystem

“…Furthermore, the glassy character is more pronounced as the ferrite is more inverted, and this coincides with the grain/particle size increment. rThe non-equilibrium cationic distribution that occurs in nanosized ZnFe 2 O 4 spinel ferrite modifies its long-range ordering and enhances its magnetization [1][2][3][4][5]. Magnetic ions located at tetrahedral A and octahedral B-sites of the ferrite spinel structure switch on antiferromagnetic J AB couplings that compete with antiferromagnetic J BB interactions.…”

“…Magnetic ions located at tetrahedral A and octahedral B-sites of the ferrite spinel structure switch on antiferromagnetic J AB couplings that compete with antiferromagnetic J BB interactions. Therefore, depending on the fraction of iron ions at A sites and the randomness of the cationic distribution, diverse and complex magnetic structures can be displayed by zinc ferrite nanoparticles (NPs) systems [1,2].In previous works [3,4], we showed that chemically synthesized nanocrystalline ZnFe 2 O 4 with an average grain size (D) of 6 nm is partially inverted with an inversion parameter c$0.2 (the relative fraction of Fe at A sites). Several authors have proposed that within a core-shell model, the non-equilibrium cation distribution in nanosized ferrites mainly takes place at the particle surface layer [5].…”