Thermodynamic and crystallochemical analyses were made of garnets, Ga5R3O12, where R was a lanthanide between Sm and Lu, or Y, and Al5R3O12, where R was Y, or a lanthanide between Gd and Lu. The point defects in the structure were characterized, and their content was estimated. It was shown that these garnets contained cationic defects and O vacancies. In the case of the Al garnets, improper-valence [AlVI+] ions formed at octahedral sites. In the case of the Ga garnets, and Ga-containing solid solutions, there were Ga vacancies [VIGa] at octahedral sites. In (GaxAl1-x)5Dy3O12 solid solutions, antistructural substitutional defects, (GaIV3+) and [AlVI3+], were present in addition to the above-mentioned defects which were typical of Ga garnets. The Ga3+ ions preferentially occupied octahedra because they exhibited a higher affinity for octahedral coordination than did Al3+ ions.

J.P.Vorobev, O.J.Goncharov: Neorganicheskie Materialy, 1994, 30[12], 1472-9 (Inorganic Materials, 1994, 30[12], 1576-83)