Physico-chemical characterization of the sintered materials

The characterization of these materials is mostly linked to the effect of the sulfur dioxide treatment. 

The first is the diffractogram of a sample of beta-alumina not treated with SO2. The characteristic peaks of the beta-alumina can be recognized. If we compare this diffractogram with that of the S02-treated sample, we can distinguish three peaks, located at 22.6°, 23.6° and 25.5° characteristic of the sodium sulfate (formula Na2S04). 

To prevent the presence of such a phase on the samples, we proceed to the SO2-treatment just after the sintering stage in order to prevent a weak homogenity for the sodinm sulfate. 

Nevertheless, this evolution of the surface texture has been observed in every S02-treated sample. 

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