Inversion symmetry in the spin-Peierls compound NaV2O5

TL;DR

This paper investigates the crystal symmetry of NaV2O5, revealing a centrosymmetric structure at room temperature that impacts the understanding of its valence state and the nature of its low-temperature transition.

Contribution

It clarifies the room-temperature space group of NaV2O5 as Pmmn, challenging previous non-centrosymmetric assumptions and influencing the interpretation of its phase transition.

Findings

NaV2O5 has centrosymmetric space group Pmmn at room temperature.

The vanadium valence state is non-integer due to symmetry implications.

The 34 K transition is not a simple spin-Peierls transition as previously thought.

Abstract

At room-temperature 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 of the non-centrosymmetric counterpart P21mn. 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+.