Anomalous magnetic behaviour at nano-scale of Mn2+-substituted magnesio-ferrite synthesized by auto-combustion technique

Laxmi J. Hathiya*, J. D. Baraliya, Avik Das, Debasis Sen, A. M. Gismelseed, A. A. Yousif, H. H. Joshi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The nano-crystalline mixed ferrites with the generic formula MnxMg1 − xFe2O4 (x = 0.0–1.0, step: 0.2) were prepared by the citrate-gel auto-combustion technique. Motivated by anomalous magnetic behaviour of coarse-grained MnFe2O4, the main aim was to study the influence of Mn2+ substitution in MgFe2O4 on magnetic structure at nano-regime. The compositional stoichiometry of the final ferrite products was ascertained by EDAX mapping and particle size for each sample was determined by powder X-ray diffraction, TEM, small-angle X-ray and neutron scattering techniques. The lattice constant increases with Mn-content due to larger cation (Mn2+) substitution. The distribution of cations in the tetrahedral (A) and octahedral (B) interstitial sites of the spinel lattice is determined by X-ray diffraction and Mossbauer spectral intensity analysis. The Mossbauer spectra at room temperature exhibit two sextets due to A- and B-sites for compositions x = 0.0, 0.2 and 1.0 while spectra showed central paramagnetic doublet superimposed on magnetic sextets for the samples with x = 0.4, 0.6 and 0.8, ascribed to the presence of superparamagnetic clusters. Thermal variation of AC susceptibility showed hump near the Curie temperature due to the presence of superparamagnetic clusters as corroborated by Mossbauer signature. The observed saturation magnetic moment (at temperature 5 K and applied field 9 T) is found lower compared to Neel's moment for the compositions with x > 0.2 which is explained on the basis of the exchange disorder of Fe3+ ions in the B-sites in Mn-containing ferrites.

Original languageEnglish
JournalIndian Journal of Physics
DOIs
Publication statusAccepted/In press - 2021
Externally publishedYes

Keywords

  • Combustion synthesis
  • Ferrite nanoparticles
  • Mossbauer spectroscopy
  • Small-angle X-ray and neutron scattering

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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