The Intermetallic Semiconductor ht-IrGa(3): a Material in the in-Transformation State

[Image: see text] The compound IrGa(3) was synthesized by direct reaction of the elements. It is formed as a high-temperature phase in the Ir-Ga system. Single-crystal X-ray diffraction analysis confirms the tetragonal symmetry (space group P4(2)/mnm, No. 136) with a = 6.4623(1) Å and c = 6.5688(2) Å and reveals strong disorder in the crystal structure, reflected in the huge values and anisotropy of the atomic displacement parameters. A model for the real crystal structure of ht-IrGa(3) is derived by the split-position approach from the single-crystal X-ray diffraction data and confirmed by an atomic-resolution transmission electron microscopy study. Temperature-dependent electrical resistivity measurements evidence semiconductor behavior with a band gap of 30 meV. A thermoelectric characterization was performed for ht-IrGa(3) and for the solid solution IrGa(3–x)Zn(x).