Synthesis and gas sensing properties of high porosity n-type nickel ferrite thin film assisted by altering magnetic field

• A new type high porosity NiFe2O4 thin film with 3-D microstructure had been synthesized.
• The microstructure was self-assembled and formed by magnetic field inducement.
• To NH3, our gas sensor had higher sensitivity at low temperature and faster response velocity.

NiFe2O4 thin film with high porosity based gas sensors had been prepared and their microstructure and gas sensing property were investigated. The sensing layer, consisted of perpendicular overlapped NiFe2O4 chains which were induced by altering magnetic field to self-assemble, had high porosity. The phase character and porous microstructure were characterized by X-ray diffraction (XRD) and a polarizing optical microscopy. The gas sensing tests results indicated that the sensor presented a high sensitivity to NH3 at 150 °C, and was selective to NH3 below 200 °C. The large porosity microstructure should benefit the reaction between target gas and sensing material and the detection of low concentration gas at low working temperature. In repeatability tests, the response and recovery time values had only narrow fluctuations.