A comparative study on surface morphological investigations of ferric oxide for LPG and opto-electronic humidity sensors

In the present work nanostructured ferric oxides were synthesized via hydroxide precipitation method without using any surfactant and size selection medium. The surface morphologies and structure of samples were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The structural analysis confirmed the formation of Fe2O3 with α-phase and rhombohedral structure. Optical and thermal properties were investigated by using UV–visible absorption spectroscopy and differential scanning calorimetry (DSC) techniques. Pelletizations of materials were done using hydraulic press and these pellets were investigated with the exposition of liquefied petroleum gas. Variations in resistance of the pellet with time for different concentrations of LPG were recorded at room temperature (27 °C). The maximum value of average sensitivity was found ∼5 for 5 vol.% of LPG. Our results show that the LPG sensing behavior was inspired by the different kinds of surface morphologies of Fe2O3 and inferred that the spherical porous nanoparticles synthesized via hydroxide precipitation process (S-3) had best response to LPG.