Development of wide band gap sensor based on AlNbO4 nanopowder for ethanol

Aluminium niobate (AlNbO4) nanopowder was synthesized by niobium-citrate complex process and characterized by thermal analysis (TG/DTA), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and energy dispersive X-ray spectroscopy (EDX), diffuse reflectance spectra (DRS), impedance analysis and Brunauer-Emmett-Teller (BET). The well crystalline orthorhombic AlNbO4 was obtained by heat treatment at 900 degrees C. TEM results indicated that the average size of the rectangle shaped AlNbO4 particles was 30 nm width and 60 nm length. The optical band gap of the nanopowder was estimated to be 3.63 eV. The temperature dependent conductivity of AlNbO4 was found to obey an Arrhenius relation with an activation energy value of 0.26 eV. The gas sensing behaviour of AlNbO4 nanopowder was analysed by measuring the changes in resistance of the sensor material in presence of each reducing gas such as ethanol, liquid petroleum gas and ammonia as a function of the operating temperatures, gas concentrations and the response time. The AlNbO4 nanopowder showed good sensitivity for ethanol (99%) rather than LPG (43%) and NH3 (19%) at an operating temperature of 250 degrees C. (C) 2012 Elsevier B. V. All rights reserved.