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Abstract

Reaction of iron-tellurium mixtures in the composition range from Fe0.41Te0.59 to Fe0.43Te0.57 followed by quenching to ambient temperature yields the high-temperature delta phase Fe1-xTe (0.25 < x < 0.31). Single crystals of delta phase Fe1-xTe with x = 0.31(1), x- 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 Fe1-xTe 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) angstrom, b -3.8409(6) angstrom, c=11.314(3) angstrom, beta = 90.47(1)degrees, 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.