Nanostructured Nickel Ferrite Thin Films for Gas Sensing Applications

Abstract

Nickel ferrite (NiFe₂O₄) is a spinel ferrite with semiconducting behavior, making it suitable for gas sensor applications. Thin films were synthesized using pulsed laser deposition (PLD) and annealed at different temperatures (400–700 °C). Structural analysis using X-ray diffraction confirmed the formation of spinel cubic phases, while scanning electron microscopy revealed grain sizes of 50–80 nm depending on annealing temperature. Gas sensing performance was tested against ethanol, acetone, and NO₂ gases at operating temperatures of 200–400 °C. Films annealed at 600 °C exhibited the highest sensitivity, particularly toward acetone, with response values exceeding 150% at 100 ppm. The enhanced sensitivity was attributed to increased surface area and oxygen vacancy concentration. Stability tests demonstrated consistent performance across 30 cycles. The results indicate that nanostructured nickel ferrite films are strong candidates for low-cost gas sensors in environmental monitoring.