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Abstract. The synthesis by high energy mechanical activation and structural characterization of the phases of Bi 3 TiNbO 9 are described. A fluorite-like metastable phase was identified upon heating the activated powders in the temperature range of 593 to 823 K, followed by formation of the stable Aurivillius phase above 873 K. The crystallization temperature of the fluorite phase increases with milling time. From Rietveld analysis of X-ray diffraction patterns, the fluorite cell parameter is shown to decrease, while rutile TiO 2 increases with milling time IntroductionThe mechanical activation of the powder precursors in the system Bi 2 O 3 -TiO 2 -Nb 2 O 5 allows for the formation of a stable Aurivillius Bi 3 TiNbO 9 (BTN) phase, with a high Curie temperature (~ 1213K) that provides for piezoelectric ceramics at high temperature [1,2]. Sintering at low temperature leads to a metaestable fluorite phase, which shows a great sensitivity to humidity, as has been reported by our group [3].Dense ceramics on this system were prepared by mechanical activation as reported in the work of Moure et al. [4,5], using low energy milling. Amorphous precursors were obtained with this technique after milling for 3000 h. The free energy stored in crystalline damage and continuous surface creation 0 are understood as the resource that greatly diminishes the subsequent new crystalline phase formation temperatures.In this report, high energy ball milling was used to obtain amorphous precursor powders. X ray diffraction and Rietveld analysis were used for crystalline structure determination. Thermal stability and phase transformations in the BTN system were analyzed as functions of milling time.

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