This investigation provides a thorough assessment of the physical and gas-sensing characteristics of MgO thin coatings that were produced through chemical spray pyrolysis (CSP). XRD analysis confirmed the formation of a face-centred cubic (FCC) structure. The grain size increased from 11.82 nm to 13.43 nm with rising annealing temperature, while dislocation density decreased from 86.52 to 72.61 x 10¹⁴ lines/m², indicating improved crystallinity. Morphological analysis using AFM and SEM revealed a temperature-induced evolution from flat islands to well-defined spherical nano-grains. Surface roughness (Rₐ) decreased from 10.19 nm to 4.82 nm, and particle size was reduced from 93.2 nm to 46.5 nm. Optically, the films exhibited high transparency, with a visible transmittance of 95.9% at 400°C, which decreased slightly with increasing temperature due to increased light scattering. The optical bandgap decreased from 3.86 eV to 3.75 eV. The extinction coefficient at 400 nm declined from 0.70 to 0.61. Gas sensing results showed that the film annealed at 500°C exhibited the highest NO₂ response (26.5% at 150 ppm). However, sensitivity decreased at higher temperatures due to reduced surface defects and active adsorption sites.
Keywords
MgO Thin FilmsSpray PyrolysisThermal AnnealingStructural PropertiesOptical CharacteristicsNO₂ Gas Sensor.
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