The efficiency of the nonhydrolytic sol−gel process based on the condensation between metal chlorides and metal alkoxides has been studied in the preparation of aluminum titanate gels. Solutions of aluminum and titanium precursors in the ratio Al/Ti = 2 gave gels with the same metal ratio. The structural evolution of the samples is unusual; they directly crystallize at T > 600 °C into metastable pseudo-brookite β-Al2TiO5 and are reluctant to decompose into stable TiO2 (rutile) and α-Al2O3 at 1150 °C. This behavior must be connected to the high homogeneity of the samples originating from the nonhydrolytic sol−gel process.
Résumé :
The efficiency of the nonhydrolytic sol−gel process based on the condensation between metal chlorides and metal alkoxides has been studied in the preparation of aluminum titanate gels. Solutions of aluminum and titanium precursors in the ratio Al/Ti = 2 gave gels with the same metal ratio. The structural evolution of the samples is unusual; they directly crystallize at T > 600 °C into metastable pseudo-brookite β-Al2TiO5 and are reluctant to decompose into stable TiO2 (rutile) and α-Al2O3 at 1150 °C. This behavior must be connected to the high homogeneity of the samples originating from the nonhydrolytic sol−gel process.
