Structure-property correlations of carbon and nitrogen incorporated NiFe<inf>2</inf>O<inf>4</inf>

Abstract

In this paper, carbon (C) and nitrogen (N) were incorporated into the interstitial sites of nickel (Ni) ferrite lattice. Structural studies of the incorporated NiFe2O4 (NFO) samples (C-NFO and N-NFO) using X-ray diffraction revealed changes in the values of the lattice parameter, bond angle, and bond length. Raman spectroscopic studies revealed shifts in peak positions of ${\text{E}}_{g}$ and $\text{T}_{2g}$ (3) vibrational modes of the spectra. Magnetization measurements at 20 and 300 K using vibrating sample magnetometer showed decrease in the values of $M_{s}$ upon incorporation of C/N ( $2.3~\mu _{B}$ /f.u. of C-NFO and $2.4~\mu _{B}$ /f.u. of N-NFO from $2.9~\mu _{B}$ /f.u. of NFO, at 20 K). An increase in intrinsic coercive field ( $H_{c}$ ) value (18.2 Oe of C-NFO and 14.2 Oe of N-NFO from 5.2 Oe of NFO, at 20 K) was also observed. However, a reduction in the value of first-order cubic magnetocrystalline anisotropy constant ( $K_{1}$ ) was observed upon incorporation of C/N. Microstructural analysis using scanning electron microscopic images revealed modifications in the shape and the size of the grains. The average grain size was found to be reduced upon C/N incorporation (~600 nm of NFO, while ~550 nm of C-NFO and ~400 nm of N-NFO).