Gas sensing properties of nanocrystalline tungsten oxide synthesized by acid precipitation method

WO3 2H(2)O samples were prepared by acidic precipitation of sodium tungstate solution Nanocrystalline WO3 powders were obtained after 350 and 600 degrees C calcinations. XRD patterns of these samples showed a diffraction profile similar to that of monoclinic WO3 Calcinations at 600 degrees C yield WO3 powders with particle sizes ranging (loin 60 to 170 nm whereas that for 350 degrees C calculations ale in the range of 30-150 nm The gas sensing properties of these powders in the form of thick film were investigated with and without platinum doping Gas response of thick films sintered at two different temperatures was measured at four different operating temperatures We confirm that the sensor elements made from 600 degrees C calcined powders doped with platinum sintered at 800 degrees C ate highly responsive and selective to ammonia vapour at 350 degrees C operating temperature as compared to sensor elements made from commercial powders (C) 2010 Elsevier B.V. All rights reserved