Thermal stability of γ-Fe₂O₃ nanoparticles and their employment for sensing of acetone vapours

Stability of γ-Fe₂O₃ nanoparticles-based films upon an isochronal annealing in air was investigated by x-ray diffraction, differential scanning calorimetry, and thermogravimetry. The γ-α transformation temperature increased owing to the nanoscaling of Fe₂O₃; the higher stability of the γ phase was explained on the ground of the surface free energy of nanoparticles (with the size of about 6.4 nm). Further, chemiresistors based on the Fe₂O₃ nanoparticle bilayer prepared by the Langmuir-Schaefer method were fabricated and examined in terms of their sensitivity to acetone vapours down to 500 ppb concentration in air. (paper)