Formation of Yttrium Aluminum Perovskite and Yttrium Aluminum Garnet by Mechanical Solid-State Reaction

Polycrystalline fine powder of yttrium aluminum perovskite (YAP) and yttrium aluminum garnet (YAG) have been successfully synthesized for the first time by mechanical solid-state reaction. The reaction scheme has been studied in detail. In short, the technique uses two reaction steps. First, a high-energy ball mill is used for the formation of a non-equilibrium disordered phase of Y–Al–O from a stoichiometric mixture of alumina and yttria at room temperature. Then, subsequent heating crystallizes the powder and obtains either YAP or YAG, depending on the initial chemical composition. Preparing the Al2O3–YAG system is also possible. The crystallization is completed at a maximum temperature of 1150°C, and therefore special high-temperature equipment is not required, unlike in conventional solid-state-reaction procedures.