Improved Ammonolytic Synthesis, Structure Determination, Electronic Structure, and Magnetic Properties of the Solid Solution Sn(x)Fe(4-x)N (0 ≤ x ≤ 0.9).

Abstract

We report a synthetic and theoretical study of the solid solution Sn(x)Fe(4-x)N (0 ≤ x ≤ 0.9). A previously published ammonolytic synthesis was successfully modified to achieve the metastable nitrides in phase-pure quality out of many competing phases. As TG-DSC measurements show, the thermal stability of the nitrides increases with increasing tin content. The Sn(x)Fe(4-x)N series of compounds adopts an antiperovskite-like structure in space group Pm3̅m. Various experimental and theoretical methods provide evidence that the iron substitution by tin exclusively takes place at Wyckoff position 1a and leads to a Vegard-type behavior of the lattice parameter over the compositional range, with an expection for a small internal miscibility gap around Sn(0.33)Fe(3.67)N of unknown cause. For highly tin-substituted iron nitrides the composition was clarified by prompt gamma-ray activation analysis (PGAA) and determined as Sn(0.78(3))Fe(3.22(4))N(0.95(3)) evidencing a fully occupied nitrogen position. Magnetic measurements reveal a linear weakening of ferromagnetic interactions with increasing tin concentration.