Pressure-Induced Transitions in the 1-Dimensional Vanadium Oxyhydrides Sr₂VO₃H and Sr₃V₂O₅H₂, and Comparison to...

High-pressure X-ray diffraction measurements on the layered oxyhydrides Sr₂VO₃H and Sr₃V₂O₅H₂ reveal that both compounds undergo a pressure-induced rock-salt to CsCl (B1-B2) structural transition, similar to those observed in binary compounds (oxides, halides, chalcogenides, etc.). This structural transition, observed at 43 and 45 GPa in Sr₂VO₃H and Sr₃V₂O₅H₂, respectively, relieves almost all of the accumulated strain on the infinite V-O-V ladders, such that the V-O bond lengths are almost identical at 0 and 50 GPa but are substantially compressed at intermediate pressures. The resistances of both materials with 1-dimensional VO ladders decrease with increasing pressure, but unlike SrVO₂H that contains 2-dimensional VO₂ sheets, they remain insulating even at the highest accessible pressures. The reduction in dimensionality from planar to linear VO networks reduces the dispersion of the V-O π bands that define the band gap and leads to insulating behavior at all measured pressures.