Phase Control in the Synthesis of Iron Sulfides.

The identity and repeating arrangement of atoms determine the properties of all solids. Even combinations of two atoms can have multiple crystal structures of varying stoichiometries and symmetries with vastly different electronic and chemical behaviors. The conditions of existing bottom-up routes for achieving one phase over another are serendipitous, and the links among precursor reactivity, decomposition mechanism, temperature, and time are elusive. Our studies take a systematic approach to understanding the role that the precursor kinetic decomposition has in the synthesis of iron sulfides, isolating it from other mechanistic factors. The data suggest that phase determination in binary solids can be logically predicted through the consideration of the anion stacking and thermodynamic relationships between phases. Mapping these relationships allows for the rational synthetic targeting of metastable crystalline phases.