Mössbauer study of the Ni–Zn ferrite system

Abstract

Mössbauer spectra of 57Fe in the nickel–zinc ferrite system (ZnO)x(NiO)1−xFe2O3 have been obtained, at room temperature and at 77 °K, in zero magnetic field and also in a longitudinal magnetic field of 13.5 kG, covering the full range of zinc content. The dependence of the isomer shifts, line widths, quadrupole interactions, and nuclear magnetic fields of 57Fe3+ ions in both tetrahedral and octahedral sites has been determined. The principal results of this study are (a) the confirmation of the determination of the nuclear magnetic fields by Abe et al. using NMR, and the extension of these measurements to higher zinc concentrations, (b) an indication that the hypotheses of paramagnetic centers, proposed by Gilleo, and superparamagnetic clusters, proposed by Ishikawa, are not applicable to the nickel–zinc ferrites, (c) evidence of canted spin structures, first proposed by Yafet and Kittel, (d) various effects of chemical disorder in the nickel-zinc ferrites, and (e) an observation of the effect on the Mössbauer spectrum of relaxation in a magnetically ordered iron system.

Magnetism and Structure Evolution in Ni-Zn Ferrites Thin Films - CEMS Study

“…When x = 0 (a) the spectrum is typical of the ferromagnetic inverse NiFe 2 O 4 spinel and consist of two Zeeman sextets A and B0, corresponding to tetrahedral A and octahedral B sites of Fe, respectively. In most of the references the sextet of higher hyperfine field is attributed to B position [3][4][5] (Table I) are lower by 5-8% than those reported in literature [3][4][5][6] for respective bulk materials, which is a sign of thermal magnetic relaxation effects in thin layers -like in the case of Ni-Zn ferrites nanoparticles [7,8]. In CEMS spectrum obtained for x = 0.2 zinc content besides B0 and A sextets (with small variance ∆B hf of hyperfine field distribution) the broadened sextet BN occurs which corresponds to the iron in B sites possessing n = 1−3 Zn neighbors in the nearest A sites (instead of Fe) [6].…”

“…According to Ref. [4] the reason is not the absence of local electric field gradient, but its averaging out in magnetically coupled spin system due to chemical and structural disorder. Referring to the general formula of Ni-Zn ferrites given in Sect.…”

“…The structural and magnetic order were effectively studied by means of transmission Mössbauer spectrometry in bulk [3][4][5][6] and nanocrystalline [7,8] Ni-Zn ferrites. In this work, a conversion electron Mössbauer spectrometry (CEMS) and X-ray diffraction (XRD) have been utilized for the investigation of structural and magnetic order in 500 nm thick Ni 1−x Zn x Fe 2 O 4 (0 ≤ x ≤ 1) ferrite films deposited on Si(100) substrate by laser ablation.…”

“…In this work, a conversion electron Mössbauer spectrometry (CEMS) and X-ray diffraction (XRD) have been utilized for the investigation of structural and magnetic order in 500 nm thick Ni 1−x Zn x Fe 2 O 4 (0 ≤ x ≤ 1) ferrite films deposited on Si(100) substrate by laser ablation. The formula of Ni-Zn ferrites could be denoted by [ 4 , where x is atomic percentage of Zn. Symbols A and B represent the tetrahedral and octahedral sites in the spinel structure, respectively.…”

Mössbauer Spectroscopic Studies of NiZn Ferrite Prepared by the Sol-Gel Method

“…They have a spinel configuration based on the face centered cubic lattice of the oxygen ions, with the unit cell consisting of eight formula units. Zn 2+ and Ni 2+ ions are known to have very strong preferences for the tetrahedral (A) and octahedral (B) sites, respectively, and are thus expected to have a cation distribution represented by (Zn x Fe 1-x ) A [Ni 1-x Fe 1+x ] B O 4 [12,13]. By referring to Zn 2+ as a diamagnetic ion, the Zn substitution in NiFe 2 O 4 leads to an unequal reduction in magnetic hyperfine interaction of both the A and B sublattices.…”