Crystal chemistry of rare-earth containing garnets: Prospects for high configurational entropy

Materials with high degrees of lattice configurational entropy are being studied to assess their potential as highly stable materials with potentially new and unusual properties. This report involves an assessment of the prospects for producing novel, complex multi-component oxide compounds that have the garnet crystal structure. We examine the crystal chemistry of garnets in an effort to determine if it may be possible to design so-called "high entropy oxide" garnets, i.e., garnets containing numerous cation components, such that the compounds are stable, monophasic, and offer the potential for new and unusual physical properties. In this report, we quantify configurational entropy for compounds such as garnet that possess numerous cation sublattices. Then, we consider coordination polyhedra and details of bonding in rare-earth containing garnets, in an effort to predict structural aspects of multi-component oxide garnets.