In contrast to two-dimensional (2D) monolayer materials, van der Waals layered transition metal dichalcogenides exhibit rich polymorphism, making them promising candidates for novel superconductor, topological insulators and electrochemical catalysts. Here, we highlight the role of hydrostatic pressure on the evolution of electronic and crystal structures of layered ZrS₂. Under deviatoric stress, our electrical experiments demonstrate a semiconductor-to-metal transition above 30.2 GPa, while quasi-hydrostatic compression postponed the metallization to 38.9 GPa. Both X-ray diffraction and Raman results reveal structural phase transitions different from those under hydrostatic pressure. Under deviatoric stress, ZrS₂ rearranges the original ZrS₆ octahedra into ZrS₈ cuboids at 5.5 GPa, in which the unique cuboids coordination of Zr atoms is thermodynamically metastable. The structure collapses to a partially disordered phase at 17.4 GPa. These complex phase transitions present the importance of deviatoric stress on the highly tunable electronic properties of ZrS₂ with possible implications for optoelectronic devices.
Transition metal dichalcogenides exhibit rich polymorphism, making them promising candidates for superconductors, topological insulators, and electrochemical catalysts. Here, the authors study the metallization of non-hydrostatically compressed ZrS₂ up to 45.8 GPa and find that a new high-pressure phase forms under deviatoric stress.