The low temperature fabrication of nanocrystalline MgAl2O4 spinel aerogel by a non-alkoxide sol-gel route

摘要

A novel nanorod-like spinel aerogel is synthesized by the sol-gel method combined with the supercritical technique. The Mg4Al2(OH)(14)center dot 3H(2)O and boehmite is formed in the spinel precursor aerogel and Mg4Al2(OH)(14)center dot 3H(2)O transforms into MgO and spinel at 350 degrees C. Structural transition of boehmite to gamma-Al2O3 occurs at ca. 400 degrees C, which is favorable to the further solid reaction between MgO and gamma-Al2O3 forming spinel aerogel at 500 degrees C. This formation temperature is much lower than the conventional methods. The highly pure nanorod spinel with length of 150-200 nm and width of 5-10 nm is well crystallized after 800 degrees C. The nanocrystal maintains a large specific surface of 81.87 m(2)/g after calcining at 1200 degrees C. (C) 2017 Elsevier B.V. All rights reserved.