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 degrees C, and therefore special high-temperature equipment is not required, unlike in conventional solid-state-reaction procedures.