Nanocrystalline Porous Nickel Ferrite Ceramics for Humidity Sensing Applications

Abstract

Over the last two decade, considerable interest has been received to synthesize novel ceramic nanomaterials with high humidity sensitivity characteristics for the fabrication of low-cost, fast and stable humidity sensors. This paper reports the preliminary results of humidity sensing properties of the nanocrystalline porous nickel ferrite ceramics fabricated by a conventional sintering of ultrafine nanopowders, which were successfully synthesized by soft mechanochemical processing. By using SEM and X-ray diffraction analyzes, the structural characteristics (average size of crystallites, density and porosity) of prepared NiFe2O4 ceramics were determined. At room temperature, this sensing material showed a linear response of impedance change within the wide relative humidity range from 15% to 85% at frequency of 2.5 kHz. Furthermore, the response time (adsorption process) of 26 s and the recovery time (desorption process) of 43 s have been obtained for this porous ceramic sensing material. Also, relatively small hysteresis, good repeatability and stability were also observed.