Investigations on the effect of gamma-ray irradiation on the gas sensing properties of SnO₂ nanoparticles

In recent years, SnO₂ nanoparticles (NPs) have been subjected to various modifications in order to improve their performance in sensing and other applications. Here, we report the synthesis of SnO₂ NPs by microwave irradiation, and subsequent exposure to gamma ( γ ) radiation at different doses (0–150 kGy) to induce desirable physico-chemical properties. The irradiated samples were characterized by x-ray powder diffraction (XRD), transmission electron microscopy (TEM and HR-TEM), and photoluminescence (PL) to evaluate the effect of γ -ray irradiation on their morphology and microstructure. The results revealed that the bulk crystal structure remained unchanged after irradiation, while the existence of defects and a damaged over-layer have been confirmed by PL and HR-TEM respectively. The influence of γ -irradiation on the electrical and CO sensing characteristics was also investigated in the temperature range between 150 and 400 °C. γ -irradiated SnO₂ NP based resistive sensors showed better CO sensing characteristics (i.e. higher response and lower working temperature) compared to non-irradiated SnO₂. Upon optimizing the γ -ray dose irradiation level and working temperature, a ten-fold enhancement in the response to CO has been achieved ( R / R ₀ = 12 to 50 ppm of CO in air) in 50 kGy irradiated SnO₂ NP based sensors operating at 150 °C. A possible mechanism for the enhanced sensing performance of γ -irradiated SnO₂ NPs has been proposed. (paper)