Glycerol-assisted sol-gel synthesis, optical, and magnetic properties of NiFe2O4 nanoparticles

Abstract

This work includes glycerol-assisted sol-gel preparation, and the structural, optical, and magnetic properties of nano NiFe2O4. XRD structural analysis demonstrated that NiFe2O4 nanoparticles (NPs) have a cubic inverse spinel crystal structure. The typical crystal sizes and lattice strains were examined using a Williamson-Hall modified form strain uniform deformation model (UDM). The obtained NiFe2O4 sizes increased from 12.71 ± 1.40 nm to 30.59 ± 2.63 nm as the calcination temperatures varied between 400 °C and 800 °C. TEM image showed almost round and homogenous NPs with sizes near to that computed from XRD. Optical absorption analysis depicted a strong band above 3 eV was assigned to DMSO-d6 Ni2+ → Fe3+(Td) and p-d O2− → Fe3+(Td) charge transfer excitations. The optical energy gap EgapASF(eV) almost decreased with increasing nano NiFe2O4 size. The magnetic characters; saturation magnetisation (Ms), coercivity (Hc), and remanence (Mr) were evaluated using VSM measurements at room temperature. An increase in the Ms, Hc, and Mr values was ascertained with the increase in the NPs size and then decreased. This behaviour is explained by the variation in domain structure theory.