Reducing gas sensing behavior of nano-crystalline magnesium-zinc ferrite powders.

As an effective alternative of simple binary oxides, cubic spinel oxides are considered to be attractive to make sensitive and stable gas sensor, selective to a specific gas. We have focused the present work on the investigation of the gas sensing characteristics of cubic spinel based nano-crystalline magnesium zinc ferrite powders. A wet chemical synthesis route is adopted to synthesize nano-crystalline magnesium zinc ferrite powders. The phase formation behavior and microstructure evolution of the synthesized powder has been investigated using infrared spectroscopy in conjunction with X-ray diffraction analyses and electron microscopy. The n-type semiconducting magnesium-zinc ferrite ceramic exhibits reasonably good sensitivity towards a variety of gases including carbon monoxide, hydrogen, methane and nitrous oxide. It is demonstrated that these sensors can be made selective to hydrogen gas sensing by modulating the operating temperature. The conductance transients during response and recovery processes have been modeled using Langmuir adsorption isotherm and activation energies for gas adsorption and desorption processes have been estimated from the respective thermally activated kinetic processes.