Elaboration process and structural properties

Generally, common powders are used. They are sifted in order to keep only those particles whose diameter is less than 100 pm. This material is then eold-eompressed under a pressure of 2 tons/m.  

The second method, which uses a large quantity of material, is better adapted to mass production. However, the samples have to be cut out of the obtained block. 

The sintering temperature determines the porosity, the size of the grain and the specific surface area of the material. The results obtained for temperatnres from 800°C to 1,300°C (see Table 7.1) allow us to confirm that the diameter of the pores and the diameter of the grains increases considerably with the temperatnre. 

Annealing temperature Grain diameters nm Pore radius nm Specific area mVg 

Furthermore, the microstmcture of the materials (size of the grains, porosity) has a great effect on the electric properties of a semiconductor oxide and on its electric sensitivity toward gas action.  

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