514
CRESPI et al.: Ti(IV), Zr(IV) AND Pb(II) COMPLEXES
Conclusions
The complexes were prepared, characterized and studied regarding their thermal be-
havior with the objective to establish under which conditions they can be used as pre-
cursors to obtain ceramic oxides.
The precipitation pH, the coordination of the metals to the chelant, the crystallinity
and the stoichiometry of the complexes were determined. The thermal behavior showed
that different heating rates and different atmospheres affect the steps of the thermal de-
composition as well as the formation of the final residues.
The thermal stability order was proposed to the complexes and the Ea=278 kJ mol–1
determined to the beginning of the thermal decomposition of the anhydrous complexes.
The released heat from the nitro groups could be responsible by the lower tem-
peratures in which the formation of the ceramic oxide occurs.
* * *
The authors acknowledge the financial support received from FAPESP (97/05613-6).
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