Heterostructure Fe2o3-In2o3 Nanoparticles As Hydrogen Gas Sensor

Fe2O3-In2O3 (9:1 mol.%) heterostructure nanoparticles were prepared by the thermal decomposition of stoichiometric amounts of Fe2C2O4 2H(2)O and In(OH)(3) at 400 degrees C for 20 h. The sample was characterized by x-ray diffraction (XRD), Fourier-transform infrared spectrometry, thermogravimetry-differential thermal analyzer, scanning electron microscopy/transmission electron microscopy, and a superconducting quantum interference device magnetometer. The XRD pattern could be indexed to both the rhombohedral alpha-Fe2O3 and cubic bixbyite In2O3 phases. This heterostructure system showed ferromagnetic properties (due to the presence of gamma-Fe2O3 phase) from 5 to 300 K and a spin-glass-like behavior of magnetization versus temperature under zero-field-cooled and field-cooled conditions. H-2 gas-sensing property was observed from 100 ppm to 2 ppm at 200 degrees C and 250 degrees C. Response and recovery times were about 275 s and 500 s, respectively, and the sensitivity varied from 2% to 21% as the H-2 increased from 2 to 100 ppm. The R-a/R-g varied from 1 to 1.3 and the plot of R-a/R-g versus H-2 could be fitted to the sigmoidal logistic function, y = A(2) + (A(1) - A(2)) / (1 + (x/x(0))(p).[GRAPHICS].