Electrical and sensor properties of FeNbO4:: a new sensor material

We report here the preparation, electrical, magnetic and gas sensor characterisation of the monoclinic phase (wolframite structure) of FeNbO4. Crystallographic and surface morphological studies were carried out by the powder X-ray diffraction (XRD) and scanning electron microscopic (SEM) techniques, respectively. The high electrical conductivity of FeNbO4 is due to the mixed valence nature (Fe2+/Fe3+) of Fe-ions in the Fe-O-Fe framework as confirmed by the temperature dependent magnetic susceptibility studies. Impedance studies on electrical conductivity as a function of temperature in the range of 300-673 K provided E-a as 0.210 eV. Sensor studies on FeNbO4 at various operating temperatures: show that the material is highly sensitive to H-2 and H2S at 573-623 K. A moderate sensitivity for LPG is obtained at around 673 K. (C) 1999 Elsevier Science S.A. All rights reserved.