Influence of trivalent Al–Cr co-substitution on the structural, morphological and Mössbauer properties of nickel ferrite nanoparticles

Abstract

Here, we report the influence of nonmagnetic Al3+ and magnetic Cr3+ co-substitution on the structural, morphological, magnetic and Mössbauer properties of nickel ferrite nanoparticles synthesized via sol-gel auto combustion route. Citric acid was used as a fuel and metal nitrate to fuel ratio was chosen to be 1:3. The resultant powder was sintered at 550 °C for 4 h and used for further characterizations. Single phase formation and nanocrystalline nature was confirmed through X-ray diffraction analysis. The crystallite size of all the samples calculated through Debye-Scherrer’s formula found to be in the range of 18–55 nm. The lattice constant calculated from XRD data show decreasing trend. Scanning electron microscopy technique was used to study the surface morphology of typical samples (x = 0.0 and 0.4). The average grain size determined through SEM images found to be 70 nm–35 nm respectively for x = 0.0 and 0.4 samples. The magnetic properties were investigated through magnetization and Mössbauer spectroscopy technique. The saturation magnetization measured from M-H hysteresis plot show decreasing trend with increase in Al–Cr content x. Using Mössbauer spectra the relative area of a sextet (T), Isomer shift (δ), Hyperfine Field (Hf), Quadrupole Splitting (Δ) and Line width (Γ) were calculated. Overall, the co-substitution of Al–Cr has significantly influenced the structural, morphological and magnetic properties of nickel ferrite nanoparticles.