Abstract
Pure and Gd-doped gamma-Fe2O3 nanopowders with different amount of Gd (1, 3 and 5 at. %) were successfully prepared via a sol gel technique followed by drying in supercritical ethanol. The microstructural and morphological properties of the synthesized materials have been investigated by scanning and transmission electron microscopies (SEM and TEM), X-ray diffraction (XRD) and BET analysis. Optical measurements, through photoluminescence (PL) and UV-visible analysis, were also performed. The characterization results confirmed the incorporation of Gd into the gamma-Fe2O3 matrix. Consequently, the pore size, BET surface area, optical band gap, electrical conductivity and photoluminescence of the Gd-doped gamma-Fe2O3 nanopowders were strongly affected and were found to be dependent on their composition. Compared with pure gamma-Fe2O3, Gd-doped samples display enhanced gas-sensing properties toward acetone. 3 at. % Gd-doped maghemite based gas sensor exhibited the higher response R-a/R-g = 31.2 (to 20 ppm of acetone), which is 30 times larger than that of pure gamma-Fe2O3. Moreover, the sensor also possesses a good selectivity toward acetone and signal stability.