VAPOR SENSING PROPERTIES OF A CADMIUM-OXIDE ANTIMONY OXIDE SYSTEM CERAMIC, CD2SB2O6.8

The vapour sensing properties of a tetragonal pseudo-pyrochlore, Cd2Sb 2O6.8, are reported. Cd2Sb2O6.8, prepared by a high-temperature solid- state synthesis, is an n-type semiconductor. Thick-film sensors incorp orating Cd2Sb2O6.8 as the active material were fabricated utilising sc reen printing technology. Sensors heated to 250-500 degrees C were exp osed to low concentrations of vapours associated with food spoilage (e thanol, ethyl acetate, limonene, pinene and toluene). The sensors were monitored through the current across the electrodes as a result of a small applied voltage. Tin dioxide sensors were also fabricated to act as a comparison. The results highlight considerable selectivity diffe rences between the Cd2Sb2O6.8 and SnO2 sensors, particularly with rega rd to humidity responses where the lack of response for Cd2Sb2O6.8 is crucial for an operational gas-sensor: An unusual feature is 'chiral' responses exhibited by Cd2Sb2O6.8 to limonene (orange oil) and pinene (pine oil) which may have practical applications in the stereochemistr y held.