Dissolution forms of rare-earth gallium-aluminium garnets

Single crystal spheres of rare-earth gallium-aluminium garnet crystals (R3Al5−x Ga x O12, whereR=rare-earths and 0≤x≤5) have been dissolved in H3PO4 and HBr. It was observed that on dissolution in H3PO4 the combination of faces {hk0}D and {hhl}D (withh>l) changed into the combination of {hk0}D, {hhl}D and {111}D when the Al concentration was increased, while the dissolution of rare-earth aluminium garnet crystals in HBr was not observed even after 50 hours.