Phase Stability Study of the Marcasite‐Structure Solid Solutions (Fe,TM)Sb₂ (TM = Cr, Ni) Synthesized via Combinatorial Co‐Deposition and Antimonization

Transition‐metal di‐pnictides and di‐chalcogenides of the pyrite‐marcasite family are model systems for crystal chemistry. Phase formation and stability of transition‐metal di‐antimonides in the orthorhombic marcasite structure are investigated. A two‐step synthesis of granular films, comprised of combinatorial deposition of the transition metal and subsequent antimonization at different temperatures, is employed. This technique allows to efficiently and quickly explore the possible ranges of substitution and evolution of lattice parameters within the marcasite structure. In particular, the formation and crystal structures of the (Fe,Ni)Sb 2 and the (Fe,Cr)Sb 2 substitution series are investigated. Continuous substitution of FeSb 2 (class‐A marcasite) with Ni up to Fe 0.5 Ni 0.5 Sb 2 , and the clear phase separation between Fe 0.5 Ni 0.5 Sb 2 and a Ni‐rich Ni 1− z Fe z Sb 2 phase (class‐B marcasite) is evidenced. Cr‐substituted FeSb 2 shows a subtle phase separation into a Fe‐rich Fe 1− y Cr y Sb 2 and a Cr‐rich Cr 1− z Fe z Sb 2 ‐phase (both class‐A marcasite) when synthesized at 500 °C. At a slightly higher synthesis temperature of 540 °C, the continuous substitution of Fe by Cr in FeSb 2 is possible. These results represent an example for the agility of combinatorial deposition of thin films in exploring phase diagrams of transition‐metal di‐pnictides as a unique tool to study this broad material family.