Nonhydrolytic sol-gel process: aluminum titranate gels

摘要

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 deg C into metastable pseudo-brookite β-Al_2TiO_5 and are reluctant to decompose into stable TiO_2 (rutile) and α-Al_2O_3 at 1150 deg C. This behavior must be connected to the high homogeneity of the samples originating from the nonhydrolytic sol-gel process.