Fabrication of alumina nanofibers by precipitation reaction combined with heterogeneous azeotropic distillation process

gamma-Alumina nanofibers have been prepared from a precipitation reaction between aluminum ammonium sulfate and Baker's salt solutions followed by a heterogeneous azeotropic distillation process with N-butanol and calcination at 1173 K. Experimental results indicate that the terminal pH value of the reaction mixture should be kept at 7.00-8.00 in order to obtain gamma-Al2O3 nanofibers. The resulting spherical aluminum hydrate precipitates are evolved into two-dimensional crystallized pseudoboehmite lamellae after the heterogeneous azeotropic distillation and then transformed into gamma-Al2O3 nanofibers with ca. 3-5 nm thick and 50-150 nm long after further calcination at 1173 K. The formation of gamma-Al2O3 nanofibers can attribute to the preferential growth along the longitudinal axis due to the inherent instability of the planar structure of the pseudoboehmite during the calcination process. (C) 2008 Elsevier Ltd. All rights reserved.