Low cost micro-emulsion route synthesis of Cr-substituted MnFe2O4 nanoparticles

Abstract In this study, optimized micro-emulsion route was utilised to synthesize the Cr-substituted MnFe2O4 nanoparticles. Transition metal Cr3+ cations were used to replace the Fe3+ ions because the Cr3+ ions have compatible ionic radii and are non-magnetic in nature. Further, they have the same electronic configuration, which is the primary requirement for the substitution philosophy. Cr3+ (x) contents were in the range 0 ≤ x ≥ 0.16. All derivative of manganese ferrite nanoparticles were annealed at 400 °C. The annealing at the required temperature was carried out for 4 hours under vacuum. Structural information was collected via X-ray diffraction (XRD) analysis and Fourier transform infra-red (FTIR) spectroscopy. Both XRD and FTIR confirmed FCC structure of all compositions of CrxMnFe2-xO4 nanoparticles. Various other physical parameters like lattice constant, cell volume, X-ray density, crystallite size were determined from obtained XRD data. Quantitative measurement of both divalent (Mn2+) and trivalent (Fe3+ and Cr3+) transition metal cations was calculated. FTIR spectral investigation was done to confirm the two typical bands corresponding to metal-oxygen vibrations present at A-sites and B-sites. After structural and spectral investigations, the electrical and dielectric properties were studied in detail for utilization of these ferrites for practical applications. Both electrical and dielectric properties were found in agreement with each other. The dielectric properties were carried out in frequency range 1 × 106 Hz to 3 × 109 Hz. In general, the both electrical and dielectric parameters were largely affected by Cr-substitution in MnFe2O4 nanoparticles.