Resolve the microscopic origin and structural identity of the high-pressure phase

Determine the microscopic origin of the higher-pressure structural reconstruction in ReO3 and establish whether the high-pressure state is primarily a symmetry-lowering distortion of the rhombohedral phase or a more substantial oxygen-framework reconstruction involving changes in Re–O coordination.

Background

Above approximately 34–40 GPa, ReO3 undergoes a structural reconstruction accompanied by suppression of bulk superconductivity. The diffraction data admit an R32-like average distortion, whereas first-principles calculations predict a lower-symmetry mP16-P2/c structure involving increased Re–O coordination. The authors state that the microscopic origin of this reconstruction and its relationship to superconductivity suppression remain unresolved, particularly whether the phase is a modest symmetry lowering of the rhombohedral structure or a more extensive oxygen-framework reconstruction.

References

Second, the microscopic origin of the higher-pressure structural reconstruction, and its connection to the suppression of SC remain to be further understood. In particular, whether the high-pressure state corresponds primarily to a symmetry-lowering distortion of the rhombohedral phase or to a more substantial oxygen-framework reconstruction involving changes in Re-O coordination remains under active investigation.

— The observation of bulk superconductivity in Rhombohedral ReO3 under pressure  (2609.26628 - Huyan et al., 22 Sep 2026) in Introduction; Results and discussion

At high pressures, above 34 GPa, new peaks appear at 2θ ≈ 8 deg, while high angle peaks disappear, suggesting the emergence of a new phase, that we are not able to unambiguously identify.

— The observation of bulk superconductivity in Rhombohedral ReO3 under pressure  (2609.26628 - Huyan et al., 22 Sep 2026) in Results and discussion, discussion of Fig. 2