Crystal structure and charge corder below the metal-insulator transition in the vanadium bronze β-SrV_6O_(15)

摘要

Single crystal X-ray diffraction measurements were performed on one-dimensional mixed valence vanadium bronze β-SrV_6O_(15) in which a metal-insulator transition exists at 170 K. Above 170 K the P2_1/a structure with zigzag order of Sr in the tunnels of vanadium is confirmed. In the structure below 170 K, the P2_1/a space groups retained with a b-axial threefold increased and a charge order appears. A bond valence sum analysis shows that the charge order may consist in clusters of V~(4+) regularly spaced along 1D direction.