[en] The cobalt ferrite (CoFe₂O₄) nanoparticle sensors, synthesized using cost-effective sol-gel auto-combustion method, are irradiated with 2 and 5 kGy γ-doses. Effect of γ-irradiation on the structure, morphology and porosity is studied initially and in the later stage, methanol, acetone, ammonia, ethanol and toluene volatile organic gases are exposed for monitoring their selectivity and sensitivity with pristine and γ-irradiated CoFe₂O₄ nanoparticle-pellet sensors. The 5 kGy γ-irradiated CoFe₂O₄ sensor reveals 70% response for ammonia (100 ppm) gas, with high selectivity and room-temperature chemical and environmental stabilities. For knowing the changes in the structure, morphology, porosity and gas sensing performance of CoFe₂O₄ sensors on γ-irradiation theoretical model has also been proposed and explored. Proposed γ-irradiation approach can be used for enhancing the sensitivity of other gas sensors at room-temperature. (paper)

[en] Zinc ferrite (ZnFe₂O₄) nanoparticles (NPs), synthesized using a facile and cost-effective sol-gel auto-combustion method, were irradiated with 2 and 5 kGy γ-doses using ⁶⁰Co as a radioactive source. Effect of γ-irradiation on the structure, morphology, pore-size and pore-volume and room-temperature (300 K) gas sensor performance has been measured and reported. Both as-synthesized and γ-irradiated ZnFe₂O₄ NPs reveal remarkable gas sensor activity to ammonia in contrast to methanol, ethanol, acetone and toluene volatile organic gases. The responses of pristine, 2 and 5 kGy γ-irradiated ZnFe₂O₄ NPs are respectively 55%, 66% and 81% @100 ppm concentration of ammonia, signifying an importance of γ-irradiation for enhancing the sensitivity, selectivity and stability of ZnFe₂O₄ NPs as ammonia gas sensors. Thereby, due to increase in surface area and crystallinity on γ-doses, the γ-irradiation improves the room-temperature ammonia gas sensing performance of ZnFe₂O₄. (paper)