ZNO-LI2O HUMIDITY SENSORS

Lithium-doped zinc oxide ceramics sensitive to atmospheric humidity le vels have been synthesized an tested. An optimization method is used t o achieve the required sensing characteristics. Graphite additions (20 vol.%) are made to some compositions, but the expected improvement in the response times is not observed due to the preferential orientatio n of the graphite plates during processing and the relatively low volu me fraction of large pores. The main sensing mechanism at high humidit y levels seems to be ionic in nature. The materials show good prospect s as humidity-sensing devices, comparing favourably with many of the o ther ceramic compositions reported, especially considering their low m anufacturing cost and simple processing.