Synthesis of metal ferrite (MFe2O4, M = Co, Cu, Mg, Ni, Zn) nanoparticles as humidity sensor materials

Abstract

Humidity sensitivity of metal ferrite nanoparticles [MFe2O4, M (II) = Co, Cu, Mg, Ni and Zn] prepared by solid-state reaction of inorganic precursors was studied. The process was convenient, environmentally-friendly, inexpensive and efficient. The spinel structure of the compounds prepared by this method was confirmed by XRD and FT-IR studies. The surface morphology was observed by scanning electron microscopy, and the surface area was analysed by the nitrogen adsorption/desorption study by the Brunauer-Emmett-Teller (BET) method. All the samples were subjected to dc electrical conductivity studies at room temperature. The resistance measurements as a function of relative humidity in the range of 5-98% and the sensitivity factor (Sf = R5%/R98%) were calculated. Among all the metal ferrites, zinc ferrite (ZnFe2O4) possessed the highest humidity sensitivity factor of 2895 ± 85, whereas the other compounds possessed a very low sensitivity factor. The response and recovery times of ZnFe2O4 were 330 and 80 s. © 2013 Copyright Taylor and Francis Group, LLC.