Magnetic, electrochemical and gas sensing properties of hydrothermally synthesized NiFe2O4 nanoparticles

The effect of reaction and annealing temperatures on structural, magnetic and electrical properties of the synthesized cubic spinel structure of NiFe2O4 nanoparticles using hydrothermal method were studied. The XRD pattern had shown cubic spinel structure with an average crystallite size of 40–60 nm. FTIR confirmed the presence of metal oxide bands in the region 600–400 cm−1. FESEM confirmed the spherical nature of the particle and sizes agreed with XRD. EDAX revealed the purity of the nanoparticles with peaks corresponding to elements Fe, Ni and O only. The specific surface area 149.76 m2/g was obtained from BET surface analysis. The survey spectrum of X-ray photoelectron spectroscopy (XPS) obviously exhibited characteristic peaks of Ni, Fe and O elements and their valence states. The VSM study revealed the soft ferromagnetic behaviour of the sample laying in pseudo-single domain range. Mossbauer spectra was recorded to reveal the valence state of iron and its occupancy in A-site (tetrahedral) and B-site (octahedral). The electrochemical analysis of the prepared nanoparticles were measured using three electrode system. As a sensor, the NiFe2O4 nanoparticles performed better response and recovery time of 37 and 20 s respectively towards LPG gas.