Nanocrystalline nickel ferrite thick film as an efficient gas sensor at room temperature

Nanocrystalline NiFe2O4 known to exhibit inverse spinel structure was used as a gas sensing element at room temperature. Ni ferrite nano-particles were prepared using chemical co-precipitation technique. Single phase formation of the cubic NiFe2O4 was confirmed by X-ray diffraction data. Fine powder resulted from the chemical co-precipitation reaction was used to prepare gas sensing elements in pellet and thick film forms. SEM technique was used to study the surface morphology of the sensing elements. The resistance measurements were carried out by exposing the sensing elements to various gases, namely O2, LPG, ammonia and Cl2 in a closed chamber at room temperature. It was found that the NiFe2O4 thick film sensor showed superior response than the pellet sensor. The sensing response was in the order Cl2 > ammonia > LPG > O2. The maximum response of the NiFe2O4 thick film to Cl2 and ammonia was 96% and 68%, respectively, at room temperature.