Hexagonal Phase Intergrown with the Tetragonal Weyl Semimetal TaAs

TaAs as a well-known topologiCal Weyl semimetal has attracted intense interests in recent study. OUr structural investigations on the microstructure properties of TaAs samples using Cs-corrected transmission electron microscopy and scanning transmission electron microscopy evidently show the presence of a hexagonal phase intergrown with the known tetragonal TaAs (NbAs-type). The structure of the hexagonal phase is identified to have the WC-type structure (space group P (6) over bar m2) with hexagonal c-axis along the [100](tetm) or [010](tetra). direction. The crystallographic correlation between the hexagonal and tetragonal phase, as well as the relevant local atomic motions, has been carefully analyzed.