High-pressure phase transition and amorphization of BaV₂O₆

The structural evolution of metavanadate compounds under high pressure offers valuable insights into phase transitions and changes in material properties. This study explores the structural behavior of BaV₂O₆ under pressures up to 12 GPa using powder X-ray diffraction and density-functional theory (DFT) simulations. The results indicate a phase transition from the ambient pressure orthorhombic phase (space group C222) to a monoclinic phase (space group C2) at 4 GPa, likely driven by the distortion of the vanadium oxide polyhedron. Above 10 GPa, the C2 phase undergoes amorphization, attributed to the breakdown of the infinite [VO₄] chains into [VO₃]^- units. Additionally, BaV₂O₆ exhibits anisotropic lattice contraction and a relatively low bulk modulus (B₀ ≈ 50 GPa). DFT calculations further explore the pressure dependence of enthalpy differences, Raman modes, and band structures, providing insights into the structural and electronic transformations of BaV₂O₆ under high pressure. This work deepens the understanding of the structural and band structure development of the metavanadate family under high pressure, contributing to advancements in materials science under extreme conditions.