Bulk Doping Influence on Response and Stability of Gas-Sensing Characteristics

2 Bulk Doping Influence on Response and Stability of Gas-Sensing Characteristics 

It is important that, during simultaneous study of gas-sensing and catalytic properties of doped metal oxides, it was established that, as a rule, the change of sensor response does not coincide with the change of catalytic activity of analyzed material (see Fig. 23.10) (Yamaura et al. 2000). Such behavior of tested characteristics testifies that the observed decrease of sensor response is not connected with reducing catalytic activity of sensing material, as could be assumed at first sight. 

5% Si02 Decrease of grain size and the area of intergrain contact 

15% Si02 The break of conductivity network Si02 grains 

It should be noted that the demixing of doped SnO during high-temperature annealing, which is accompanied by an increase in the concentration of the second phase, is a common phenomenon for metal oxides (Nowotny 1988). Usually it is stated that this effect takes place at 800-900 °C. However, on the basis of results of the annealing influence on the lattice parameters of doped SnO 

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