Sol-gel synthesis of yttrium aluminum garnet (YAG): effects of the precursor nature and concentration on the crystallization

Abstract

The sol–gel synthesis of yttrium aluminum garnet (YAG) was performed using different metal precursors (salts and alkoxides of aluminum and yttrium) and metal concentrations (up to a concentration factor of 7.4). The cross-reactivity of the aluminum and yttrium precursors is not clear, and generally, the sol–gel process leads to polyphasic samples consisting of hexagonal YAlO3 and a monoclinic yttrium-aluminum oxide. Nevertheless, the high reactivity of the yttrium precursor can be offset by the use of an aluminum alkoxide and yttrium salt as the precursors, which results in the synthesis of pure-phase YAG at 1000 °C. The effects of the metal concentration in the sol–gel synthesis on the crystallite size of the resulting YAG are reported for the first time and are found to be significant with the crystallite size varying from 55 to 123 nm. Repeated experiments demonstrate that the proposed synthesis protocol is relatively robust.