Room-Temperature Superstructure of ZrV2O7

The structure of ZrV2O7, zirconium pyrovanadate, has been refined from single-crystal synchrotron X-ray data. As with other phases in the AM 2O7 family, ZrV2O7 shows a set of strong reflections, which can be explained on the basis of a cubic unit cell with a = 8.765 Å, and a family of much weaker reflections due to a 3 × 3 × 3 superstructure. The superstructure has been refined to RF = 0.036 (a = 26.296 Å, Pa3¯, 6972 reflections) and contains highly regular ZrO6 and VO4 polyhedra. Of the six unique V2O7 groups, two are constrained by symmetry to contain linear V—O—V linkages, while the remaining four are free to bend away from 180°. The structural distortions from the ideal high-symmetry structure to the observed room-temperature structure are described.