Electronic controls on transition-metal incorporation in pyrite: insights from ab initio simulations

Pyrite is one of the most abundant sulfide minerals in the Earth’s crust and can host a wide range of transition metals. However, due to their higher electron counts and atomic sizes different from that of Fe, these substitutions often destabilize the lattice, and the mechanisms controlling their incorporation remain poorly understood. Here we use ab initio simulations to systematically investigate transition-metal substitution in pyrite, using Au-As coupling as a representative example within a broader set of transition-metal systems. We analyze defect formation energies, lattice distortions, and electronic structures for single and double substitutional configurations. Isolated substitutions are generally thermodynamically unfavorable, whereas joint substitutions are more likely to take place. In particular, anion-site dopants with fewer valence electrons than sulfur, such as arsenic, facilitate the incorporation of large-radius transition metals by promoting locally constrained coordination environments and alleviating lattice strain. Electronic structure analyses show that impurity stability is governed by band filling and Fermi-level positioning. Double substitution enables electronic compensation, eliminates mid-gap states, and lowers defect formation energies across multiple transition-metal systems. These results establish electronic compensation as a fundamental control on transition-metal enrichment in pyrite, with implications for pyrite-hosted ore deposits and trace-metal capture across the pyrite life cycle.