FAST GAS SENSORS BASED ON METAL-OXIDES WHICH ARE STABLE AT HIGH-TEMPERATURES

Recently, research into the characteristics of semiconductor metal oxi des that are stable at high temperatures with a view to providing repr oducible detection of oxygen and reducing gases has intensified. First of all, there is a discussion of the specifics relating to these mate rials, for example the reduction of the effects of grain-boundary barr iers on the conduction mechanism, the reduction of the humidity cross- sensitivities and also on the various reaction mechanisms. Then, the t echnology for constructing gas sensors of this kind will be described. Examples that have already been implemented, for example, lambda, det ection, O-2 measurements in the exhaust gases from incinerators, metha ne alarms, and air quality control, as well as certain trends in devel opment, are discussed. (C) 1997 Elsevier Science S.A.