A desirable candidate would be air stable, have a large europium cation separation to limit unintended interactions, consist of mononuclidic elements, and have a polar europium site symmetry to allow observation of the narrow 5 D 0 → 7 F 0 transition. These conditions, along with europium's tendency to be divalent, severely limit the known viable materials that may achieve the desired narrow inhomogeneous linewidth. On the other hand, the chemical similarity of lanthanide elements makes them ideally suited for using known structures as prototypes for building unrealized Eu 3+ compounds. With prototype structures from material databases, we quickly increase our potential candidate list but with no indication of chemical stability.