Electrical and sensor properties of FeNbO4: a new sensor material

Abstract We report here the preparation, electrical, magnetic and gas sensor characterisation of the monoclinic phase (wolframite structure) of FeNbO 4 . 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 FeNbO 4 is due to the mixed valence nature (Fe 2+ /Fe 3+ ) 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 FeNbO 4 at various operating temperatures show that the material is highly sensitive to H 2 and H 2 S at 573–623 K. A moderate sensitivity for LPG is obtained at around 673 K.