Nitrogen dioxide and volatile sulfide sensing properties of copper, zinc and nickel chromite

Abstract

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