Half-Heusler phase related structural perturbations near stoichiometric composition FeZnSb

Half-Heusler phases XYZ (Pearson symbol cF12) are chemically versatile and rich in physical properties. The half-Heusler phase in the Fe–Zn–Sb ternary system was reported in the year 2000. In this work, two new ternary phases are identified in the vicinity of the equiatomic composition FeZnSb in the same system: Fe1−xZnSb (tetragonal, space group P4/nmm, Pearson symbol tP6−δ, Z=2: a=4.1113(6) Å, c=6.0127(12) Å for x=0.08 (1), and a=4.1274(6) Å, c=6.0068(12) Å for x=0.12 (2)); and Fe7.87Zn6.72Sb8 (Fe0.98Zn0.84Sb) (3) (cubic, space group Fm-3m, Pearson symbol cF96−δ, Z=4, a=11.690(13) Å). 1 and 2 crystallize in the PbFCl-type structure, and 3 adopts a unique 2×2×2 supercell of a normal half-Heusler structure. The structures of both the tetragonal and cubic phases can be described as assemblies of half-Heusler structure related subunits. Electrical resistivity measurement on the pure sample of 2 shows it has metallic-like behavior, and its thermal and magnetic properties are also characterized.