SELECTIVE NITROGEN-DIOXIDE SENSOR-BASED ON NICKEL COPPER-OXIDE MIXED WITH RARE-EARTHS

Scandium-doped nickel copper oxide bulk, which consists of Ni0.8Cu0.2O , CuO, Sc2O3, and Sc2Cu2O5, responds only to NO2 (50-500 ppm) among NO x gases. Thin films of the oxide are prepared by an r.f. magnetron spu ttering method, and their NOx-sensing characteristics are studied. The electrical resistivity of the film decreases with an increase in the NO2 concentration, while it increases with NO content. As is expected, the film responds to NO2 more sensitively than the bulk shape. Howeve r, the film responds not only to NO2 but also to NO. The disappearance of crystalline Sc2Cu2O5 in the film might affect the sensing performa nce for NOx.