A microstructural model of semiconducting gas sensor response: The effects of sintering temperature on the response of chromium titanate (CTO) to carbon monoxide

A simple model of the microstructure of a sensor as a network of three resistors, representing the surface, the bulk and the particle boundary, is combined with a simple model of sensor response in order to understand the effects of sintering temperature on response of a ceramic gas-sensitive resistor. This description accurately fitted the response of chromium titanium oxide to carbon monoxide over a range of four orders of magnitude in gas concentration. The parameters representing the microstructure are found to vary with sintering temperature according to predictions made from microscopy of the structures. The parameter representing chemistry also varied with sintering temperature: understandable because titanium segregation, which is the major determinant of the charge carrier distribution, varies with sintering temperature.