Preparation of Gadolinium Gallium Garnet [Gd ₃ Ga ₅ O ₁₂ ] by Solid‐State Reaction of the Oxides

We have prepared dense polycrystalline gadolinium gallium garnet (GGG) by solid‐state reaction of the oxides. The oxides were prereacted at 1350°C, ground, pressed, and sintered at 1650°C, yielding 97% dense samples. Ga 2 O 3 evaporated from the sample surface leaving Gd 4 Ga 2 O 9 that could spall off the sample. For the short times needed to sinter samples, the bulk composition of the material remained essentially constant. The microhardness of the GGG was 11.8 ± 1.2 GN · m −2 .