Experimental and Numerical Modelling of a Nanostructured Nickel Ferrite-Based Ammonia Gas Sensor

In the present study, a comparison of experimental and numerical models based on the interaction of ammonia gas (NH 3 ) with a nanostructured nickel ferrite (NiFe 2 O 4 ) sensing layer is presented. To construct the sensor model for reducing gas sensors, chemisorption of ambient oxygen atoms at the sensor surface is explored. The nickel ferrite sensing film functions as an n -type semiconductor. The chemical adsorption of monatomic oxygen on the sensor layer causes the film resistance to decrease. The presented sensor model is based upon the physics of particle free energy of the electronic system in equilibrium. Eventually, the ratio of conduction electron concentration with or without gas interaction is calculated to predict the sensor response. A NiFe 2 O 4 -based gas sensor has been fabricated and presented with structural and morphological characterizations of the sensing layer. The approximate value of sensor parameters as a function of chemical reactions occurring at the sensor surface has been extracted from the experimental data. Sensor response of different concentrations of ammonia has been calculated as a function of operating temperature of NiFe 2 O 4 nanostructured thin film. The maximum simulated sensor response was ~ 90% for P NH3 = ∞, i.e., when the presence of ammonia was in abundance. The maximum sensor response towards 1000 ppm of ammonia at 410 K was measured to be ~ 65.29% compared to the simulated response of ~72% for the same ammonia concentration and operating temperature.