Crystal structure and magnetism of Fe${}_{1-x}$Te (x=0.31)

Reaction of iron-tellurium mixtures in the composition range from Fe${}_{0.41}$Te${}_{0.59}$ to Fe${}_{0.43}$Te${}_{0.57}$ followed by quenching to ambient temperature yields the high-temperature δ phase Fe${}_{1-x}$Te (0.25 < x < 0.31). Single crystals of δ phase Fe${}_{1-x}$Te, with x=0.31(1), are obtained by reacting Fe-Te mixtures with nominal composition Fe${}_{0.43}$Te${}_{0.57}$ in closed ampoules at 973 K for 15 days before quenching to ambient temperature. In accordance with the chemical transport behavior of other phases in the iron-tellurium system, the refined composition of the single crystals Fe${}_{1-x}$Te with x=0.31(1) suggests that crystallization and growth preferably occur in the tellurium-rich part of the homogeneity range.The resulting crystals adopt a monoclinic crystal structure with unit cell parameters a=6.645(2) Å, b=3.8409(6) Å, c=11.314(3) Å, β=90.47(1)°, Z=4 (space group I2/m, non-standard setting of C2/m). Single crystal structure refinement reveals a NiAs motif with partial occupation in every second iron layer along [001]. Magnetic susceptibility measurements indicate antiferromagnetic order below 400 K. (© 2022 The Authors. Zeitschrift für anorganische und allgemeine Chemie published by Wiley-VCH GmbH)