Influence of fuel to oxidizer ratio on gas sensing characteristics of ZnFe2O4 nanoparticles

Highly porous zinc ferrite (ZnFe₂O4) nano-size powders are synthesized by varying fuel to oxidizer ratio. The metal nitrates are used as oxidizers while glycine is used as a fuel. The synthesis of material is carried out using an auto-combustion method. It is observed that the enhancement of magnetization occur with the enhancement of `Fuel to Oxidizer´ ratio i.e. Glycine to metal Nitrate (G/N) ratio. The structural, morphological, and magnetic features of samples are studied using XRD, SEM, EDAX, BET and VSM techniques. At the microscopic level, the materials exhibit a formation of spongelike structure containing nano-size particles. The XRD measurements confirm the formation of single phase spinel structure of zinc ferrite (ZnFe₂O₄). As a case study, the response of materials to ethanol gas is studied. It is observed that higher G/N ratio lead to lowering of gas sensitivity as well as operating temperature. The results are discussed in terms of reactions of surface oxygen with ethanol gas.