Synthesis and characterization of 3D topological insulators: a case TlBi(S_1- Se )₂

In this article, practical methods for synthesizing Tl-based ternary III-V-VI₂ chalcogenide TlBi(S[Formula: see text]Se )₂ are described in detail, along with characterization by x-ray diffraction and charge transport properties. The TlBi(S[Formula: see text]Se )₂ system is interesting because it shows a topological phase transition, where a topologically nontrivial phase changes to a trivial phase without changing the crystal structure qualitatively. In addition, Dirac semimetals whose bulk band structure shows a Dirac-like dispersion are considered to exist near the topological phase transition. The technique shown here is also generally applicable for other chalcogenide topological insulators, and will be useful for studying topological insulators and related materials.