Site occupation and solubility limit of Sc in Lu3Al5O12

Crystallographic study of the Lu3Al5O12:Sc system shows existence of a wide range of compositions involving substitutions by Sc for both six-fold octahedral and eight-fold dodecahedral sites of the lattice. In comparison to other rare-earth garnets, the total amount of Sc that can be tolerated by this matrix is however much lower. The limited solubility of Sc is associated with the small size difference between the constituent atoms, which approaches a critical value with increasing the Sc content. Preparation of clear single-phase solid solution crystals requires an accurate account of site occupation preferences.

► We examine the phase and elemental composition of Sc containing LuAG garnets. ► We determine the site occupation and solubility limits of Sc in octahedral and dodecahedral sites of the lattice. ► Sc does not enter the octahedral sites in concentrations above 45%. ► Growth of quality crystals requires an accurate control of the melt composition.