查看文章

Thin nanoporous anodic alumina films, of low aspect ratio (1:1), with two distinctive pore sizes and morphologies were prepared by two-step constant-current anodising of aluminium layers on SiO₂/Si substrates in 0.4moldm⁻³ tartaric (TA) and malonic acid (MA) electrolytes and then modified by open-circuit dissolution. The anodic films were employed as a support material for sputtering-deposition of thin WO₃ layers in view of exploiting their gas sensing properties. The films and deposits were characterized by scanning electron microscopy, X-ray diffraction and electric resistance measurements at fixed temperatures in the range of 100–300°C upon NH₃ and CO gas exposures. Test sensors prepared from the annealed and stabilized alumina-supported WO₃ active layers were insensitive to CO but showed considerably enhanced responses to NH₃ at 300°C, the sensitivity depending upon the anodic film nature …