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 AM₂O₇ 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 R_F = 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.

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