Structural Evolution of BaVS3 Under Pressure

Abstract

Results of a high-pressure angle dispersive X-ray diffraction and electrical resistance study on quasi one-dimensional BaVS3 are reported. They show that no structural transition occurs up to 26 GPa. However, there is evidence of gradual disordering indicated by the broadening of the diffraction lines. p-V data fitted to a Birch-Murnaghan equation of state yields a value of the room-temperature, ambient-pressure bulk modulus of 77.3 GPa with a pressure derivative of 4.03. It is proposed that under compression structural phase transitions resulting from static displacements of V ions that are observed at low temperature are suppressed. Instead, a partial “polymerization” of V ions that is dynamic in nature and allows enhanced hopping conduction, starts near 3 GPa and saturates above 15 GPa.