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inorganic compounds
At room-temperature, sodium pentaoxodivanadate, NaV2O5, was found to have the centrosymmetric space group Pmmn. This space group implies the presence of only one kind of V site, in contrast with previous reports [Carpy & Galy (1975). Acta Cryst. B31, 1481-1483] of the non-centrosymmetric P21mn counterpart. This indicates a non-integer valence state of vanadium. Furthermore, this symmetry has consequences for the interpretation of the transition at 34 K, which was ascribed to a spin-Peierls transition of one-dimensional chains of V4+.