Phase Equilibria in the Mo–Fe–P System at 800 °C and Structure of Ternary Phosphide (Mo1–xFex)3P (0.10 ≤ x ≤ 0.15)

Construction of the isothermal section in the metal-rich portion (1–xFex)2P (x = 0.30–0.82) and (Mo1–xFex)3P (x = 0.10–0.15). The occurrence of a Co2Si-type ternary phase (Mo1–xFex)2P, which straddles the equiatomic composition MoFeP, is common to other ternary transition-metal phosphide systems. However, the ternary phase (Mo1–xFex)3P is unusual because it is distinct from the binary phase Mo3P, notwithstanding their similar compositions and structures. The relationship has been clarified through single-crystal X-ray diffraction studies on Mo3P (α-V3S-type, space group I4̅2m, a = 9.7925(11) Å, c = 4.8246(6) Å) and (Mo0.85Fe0.15)3P (Ni3P-type, space group I4̅, a = 9.6982(8) Å, c = 4.7590(4) Å) at −100 °C. Representation in terms of nets containing fused triangles provides a pathway to transform these closely related structures through twisting. Band structure calculations support the adoption of these structure types and the site preference of Fe atoms. Electrical resistivity measurements on (Mo0.85Fe0.15)3P reveal metallic behavior but no superconducting transition.