In₂O₃+xBaO (x=0.5–5at.%) – A novel material for trace level detection of NOₓ in the ambient

Indium oxide (In₂O₃) doped with 0.5–5at.% of Ba was examined for their response towards trace levels of NOₓ in the ambient. Crystallographic phase studies, electrical conductivity and sensor studies for NOₓ with cross interference for hydrogen, petroleum gas (PG) and ammonia were carried out. Bulk compositions with x≤1at.% of Ba exhibited high response towards NOₓ with extremely low cross interference for hydrogen, PG and ammonia, offering high selectivity. Thin films of 0.5at.% Ba doped In₂O₃ were deposited using pulsed laser deposition technique using an excimer laser (KrF) operating at a wavelength of (λ) 248nm with a fluence of ∼3J/cm² and pulsed at 10Hz. Thin film sensors exhibited better response towards 3ppm NOₓ quite reliably and reproducibly and offer the potential to develop NOₓ sensors (Threshold limit value of NO₂ and NO is 3 and 25ppm, respectively).