Self-catalyzed growth of nonstoichiometric mullite nanodiskettes

The nonstoichiometric Al-rich single crystal mullite nanodiskettes were prepared by sol–gel method without any catalysts, which has been demonstrated to be simple, efficient, and generally give high yields. The products have diskette shape with about 200–300 nm in diagonal and several tens nanometers in thickness. The nanodiskettes’ growth is favored along four directions of ±[0 0 1] and ±[2 1 0], with the typical growth along [ 1   2 ¯   0 ] direction suppressed, which directly leads to the formation of mullite nanodiskette. A large proportion of the Raman scattering has been lost owing to the presence of nanodiskettes. Detailed structural characterizations suggested that the growth of this novel nonstoichiometric structure was induced by the self-catalyzed process thanks to the presence of surface excess Al adlayers on mullite surfaces.