Sol–gel processing of β-eucryptite: an 27Al nuclear magnetic resonance investigation in sol stage

Preparation of β-eucryptite by the sol–gel process from aluminum nitrate and aluminum-sec-butoxide was investigated. Preparation of β-eucryptite from aluminum nitrate, TEOS and LiOH resulted to the formation of β-eucryptite as the major crystalline phase along with a small amount of minor phase(s). Single-phase β-eucryptite was prepared from aluminum-sec-butoxide, TEOS and LiOEt with the aid of Hacac in 2-methoxyethanol and characterized by XRD and TGA/DSC. The coordination states of aluminum atoms after reaction of aluminum-sec-butoxide with other reactants in the preparation of β-eucryptite were determined by 27Al NMR. The 27Al NMR indicated that before gelation, all aluminum atoms are in the six-coordinated states and infrared (IR) spectroscopy showed that the SiOAl bond forms after gelation which is important for preparation of single-phase β-eucryptite by the sol–gel method.