NITROGEN-DIOXIDE AND VOLATILE SULFIDE SENSING PROPERTIES OF COPPER, ZINC AND NICKEL CHROMITE

Polycrystalline powders of CuCr2O4, ZnCr2O4 and NiCr2O4 were prepared from the decomposition of metal nitrates with glycine, and their struc tures confirmed by X-ray diffraction. The three spinels were mixed wit h ethyl cellulose dissolved in a suitable solvent (80:20 toluene-ethan ol) to form pastes which were applied to substrates and dried. The gas sensing properties of the resulting thick films were investigated wit h ppm levels of NO2, CH3SH and C2H5SH at 220 degrees C. It was found t hat the spinels can be used to detect the presence-of these gases. Fur ther experiments showed that by substituting some of the A or B cation s with Li and Mg, respectively, the gas sensing properties of the-spin els can be altered significantly.