Influence of Temperature on Reducing Gas Sensing Performance of Nanocrystalline Zinc Ferrite

Pure phase, zinc ferrite (ZnFe2O4) nanoparticles were synthesized at lower temperature (80 °C) by auto combustion synthesis method. The resulting ‘as synthesized’ powder was heat treated (HT) at 560 °C for 2 h in air atmosphere. As-synthesized particles had sizes ~10 nm with spherical shape. Further, these spherically shaped nanoparticles tended to change their morphology to hexagonal plate shape with increasing HT temperature. The band gap of the ‘as synthesized’ and HT zinc ferite, as determined by using UV–Vis spectroscopy were found to be 1.92 and 1.86 eV respectively. Gas responses of the ZnFe2O4 nanoparticles were measured by exposing them to ethanol gas vapors. It was found that the zinc ferrite nanoparticles exhibited various sensing responses to ethanol gas at different operating temperature. The best sensitivity was observed at low temperature for ‘as synthesized’ ferrite nanoparticles than HT zinc ferrite nanoparticles. Sensing material that had smaller particle size and larger specific surface area was observed to have larger gas sensitivity and vice-versa.