Structural, morphological, electrical, and magnetic characteristics of 20MnFe2O4-80SiO2 nanocomposite synthesized by the one-pot auto-combustion route

• Published in: Applied physics. A, Materials science & processing Materials science & processing, 2022-09, Vol.128 (9), Article 812
• Main Authors: Salehizadeh, S. A., Costa, B. F. O., Rodrigues, V. H., Greneche, J.-M., Valente, M. A., Graça, M. P. F.
• Format: Article
• Language: English
• Subjects: Activation energy; Applied physics; Characterization and Evaluation of Materials; Combustion; Condensed Matter Physics; Crystallites; Crystallization; Electrical measurement; Equivalent circuits; Ferric ions; Grain boundaries; Machines; Magnetic properties; Manufacturing; Materials science; Morphology; Mossbauer spectroscopy; Nanocomposites; Nanocrystals; Nanotechnology; Nyquist plots; Optical and Electronic Materials; Physics; Physics and Astronomy; Processes; Silicon dioxide; Spectra; Spectrum analysis; Surfaces and Interfaces; Temperature; Temperature dependence; Thin Films
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-022-05876-4

We report an investigation of the structural, morphological, the ac-dc electrical, magnetic, and Mössbauer spectroscopy properties of 20MnFe 2 O 4 -80SiO 2 nanocomposite prepared using a one-step and facile auto-combustion approach. XRD pattern shows the formation of MnFe 2 O 4 nanocrystallite without any crystallization of the SiO 2 phase. However, the presence of a secondary phase of the nanosized α-Fe 2 O 3 particles was also detected. The morphological analysis showed aggregation of polygonal magnetic nano-crystallites dispersed non-uniformly in a silica matrix. The dc electrical measurements performed on a wide range of temperatures from 120 to 400 K showed the semiconducting nature of the nanocomposite. The temperature dependence of dc conductivity could be perfectly fitted to the nearest neighborhood hopping model with activation energy, ΔE NNH , of 0.45 eV. The Nyquist plots demonstrated a nonmonotonous thermally activated trend and non-Debye relaxation behavior. An equivalent circuit was successfully fitted to the complex impedance spectra. The variation of both grain and grain boundary conductivities as a function of temperature exhibited three distinct regions, semiconducting-metallic-semiconducting with different activation energies over the measured temperature window. The provided description of such behavior is further advocated by the ac conductivity and dielectric modulus studies. VSM measurements revealed that the nanocomposite magnetic behavior deviates from the ideal non-interacting superparamagnetic picture, due to the presence of α-Fe 2 O 3 nanocrystalline impurities and relatively intensive exchange interactions between ions. Mössbauer spectra showed the presence of Fe 3+ ions with sixfold environment and also confirmed the existence of a sextet related to α-Fe 2 O 3 with a quantity of about 20% out of magnetic components. Fe 3+ superparamagnetic doublets were also found within the fitting procedure.